Search

Introduction: Analysis using cardiac iodine-123 metaiodobenzylguanidine (MIBG) scintigraphy with regions of interest (ROIs) is useful for assessing myocardial sympathetic activity. However, manual placement of the cardiac ROI is sometimes difficult because myocardial MIBG uptake is reduced in patients with heart failure. A new method was developed to reconstruct the semiautomated cardiac ROI in a sympathetic denervated heart., Materials and Methods: Using dynamic planar data, a summed image was generated and the matrix size was changed. Then, the radial count profiles originating from the center of the left ventricle were generated to extract the myocardial count profiles. An asymmetric Gaussian distribution was fitted to each profile and the epicardial border was defined by the threshold method. This program was tested in 50 patients, and its reproducibility was validated when compared with the manual tracing method., Results: The semiautomated method yielded a better quality image compared with the standard image with higher counts. Cardiac ROIs were generated successfully in each patient within normal limits. The intraobserver and interobserver agreements were excellent (P<0.0001 each). This approach showed a significantly higher consistency in measuring the heart-to-mediastinum ratio as compared with the manual tracing method (P<0.05)., Conclusion: The semiautomated method is useful in generating cardiac ROIs with high reproducibility in myocardial MIBG imaging.

Patients with isolated congenital complete atrioventricular block (CCAVB) occasionally develop dilated cardiomyopathy (DCM), despite early pacemaker implantation. However, the etiology of the DCM and its relationship to permanent ventricular pacing are not fully understood. Twenty-five patients with CCAVB underwent (99m) technetium (Tc) myocardial perfusion scintigraphy. Five patients were studied before and after pacing, providing a total of 30 image sets, which were divided into three groups; group 1: CCAVB before pacemaker implantation (PMI) (n = 11); group 2: CCAVB after PMI who did not subsequently develop DCM (n = 13); group 3: CCAVB after PMI who subsequently developed DCM (n = 6). Perfusion defects on single-photon-emission computed tomography (SPECT) were identified in group 1, 0 of 11 patients; group 2, 85% of patients; and group 3, 100% of patients. In groups 2 and 3, in patients with right ventricular pacing, the perfusion defects were mainly in the septum or between the apex and septum. On 20 segments' polar maps, the distribution of %uptake showed a similar pattern in groups 2 and 3, the degree of decreased %uptake and the number of segments with decreased %uptake being more severe in group 3. "Artificial" left bundle branch block (LBBB) pattern myocardial contraction induced by right ventricular pacing decreased myocardial perfusion around the apex and septum. Some patients with CCAVB will develop left ventricular dysfunction caused by artificial LBBB-induced interventricular asynchrony.

Objective: Standards for myocardial single-photon emission computed tomography (SPECT) adapted for a Japanese population were not available. The purpose of this study was to create standard files approved by the Japanese Society of Nuclear Medicine and to make known the characteristics of the myocardial perfusion pattern of this population., Methods: With the collaboration of nine hospitals, a total of 326 sets of exercise-rest myocardial perfusion images were accumulated from subjects with a low likelihood of cardiac diseases. The normal database included a (99m)Tc-MIBI/tetrofosmin myocardial perfusion study with 360 degrees (n = 80) and 180 degrees (n = 56) rotations, (201)Tl study with 360 degrees (n = 115) and 180 degrees rotations (n = 54) and a dual-isotope study with 360 degrees rotation (n = 27). The projection images were transferred by digital imaging and communications in medicine (DICOM) format and reconstructed and analyzed with polar maps., Results: The projection data from multiple centers were successfully transferred to a common format for SPECT reconstruction. When the average values were analyzed using a 17-segment model, myocardial counts in the septal segment differed significantly between 180 degrees and 360 degrees rotation acquisitions. Regional differences were observed between men and women in the inferior and anterior regions. A tracer difference between (99m)Tc and (201)Tl was also observed in some segments. The attenuation patterns differed significantly between subjects from the United States and those from Japan., Conclusions: Myocardial perfusion data that were specific for the Japanese population were generated. The normal database can serve a standard for nuclear cardiology work conducted in Japan.

Although a second-generation histamine H(1) blocker terfenadine induced torsades de pointes (TdP) arrhythmias in patients via the blockade of a rapid component of delayed rectifier K(+) current (I(Kr)), such action of terfenadine has not been detected in previous animal models. We analysed the potential of the canine persistent atrioventricular block heart, a new in vivo proarrhythmia model, to detect a torsadogenic effect of terfenadine of an oral dose of 3 or 30 mg kg(-1). The doses can provide therapeutic to supra-therapeutic plasma concentrations as an anti-histamine. In 2 weeks of bradycardiac heart model, there were no significant changes in any of the electrocardiogram parameters after the administration of both doses of terfenadine. In 4-6 weeks of bradycardiac heart model, the low dose of terfenadine hardly affected any of the electrocardiogram parameters except that it induced TdP in one out of six animals. The high dose significantly decreased the atrial rate and ventricular rate, prolonged the QT interval, and induced TdP in five out of six animals. Moreover, temporal variability of repolarization increased after the high-dose administration. These results suggest that long-term bradycardia caused by atrioventricular block can remodel the canine heart to detect terfenadine-induced TdP.

Coronary revascularization with PTCA or by means of CABG surgery is frequently used in the care of patients with ischemic heart disease. Before revascularization is performed, stress myocardial perfusion imaging may assist in management decisions by demonstrating the presence of myocardial ischemia and viability, and delineating the severity and extent of coronary artery disease. The presence of myocardial ischemia may provide an indication for revascularization, even in asymptomatic persons. The significance of equivocal lesions may be determined and the culprit vessel may be successfully defined by this radionuclide technique. Recently, the quantitative estimation of myocardial flow reserve with N-13 ammonia PET and the precise detection of myocardial viability with F-18 FDG PET have been introduced to support the limitations of conventional SPECT imaging. After revascularization, these radionuclide techniques are useful to demonstrate improvement of myocardial perfusion or flow reserve, and are also very important to determine restenosis after PCI and graft disease after CABG surgery.

Background: The role of aldosterone has been less investigated compared to the renin-angiotensin-aldosterone system in renovascular hypertension. The purpose of the present study was to compare the effects of a selective aldosterone receptor blocker, eplerenone (EP), and an angiotensin II receptor type 1 antagonist (AT1RA), losartan (LO) on cardiac and renal damage produced by two-kidney, one-clip (2K-1C) renovascular hypertension in rats., Method: Wistar rats (n = 48) were placed on one of six groups. Group 1 received sham operation. From group 2 to 6, all rats were made as 2K-1C renovascular hypertension. Group 2 received vehicle. Group 3 orally received 100 mg/kg/day of EP from the initiation of the study. Group 4 received 100 mg/kg/day of LO, from the initiation of the study. Groups 5 and 6 received EP and LO from the 4th week after the clipping respectively. Systolic blood pressure (SBP) and urinary protein excretion (UPE) were measured before and every 2 weeks. The remnant kidney was obtained for histopathological analysis and for measurement of endothelial cell nitric oxide synthase (ecNOS) gene expression (GE)., Results: SBP increased in the placebo group (132.1 +/- 2.4 vs. 115.0 +/- 0.6 mm Hg in sham group at week 10, p = 0.019). Treatment with LO or EP from the beginning of the study decreased SBP significantly as measured in the sham group at week 10. The placebo group developed significant UPE (21.7 +/- 1.9 mg/day) compared with the sham group (13.4 +/- 0.8 mg/day, p < 0.05). Treatment with both LO (12.5 +/- 1.5 mg/day, p < 0.01 vs. placebo) and EP (14.8 +/- 1.0 mg/ day, p < 0.05 vs. placebo) significantly decreased UPE. On the other hand, the late start of treatment with EP failed to decrease the increased UPE. UPEs were not significantly different between the LO- and EP-treated groups throughout the study. There was no significant pathological change in heart and kidney in all groups. In heart, ecNOS GE was significantly increased in the EP-treated (from the beginning of the study) rats compared with placebo group (0.47 +/- 0.01 vs. 0.43 +/- 0.01, p < 0.05). LO did not have an effect on ecNOS GE in heart. In aorta, ecNOS GE was significantly increased in the two EP-treated groups compared with the placebo group (0.22 +/- 0.01, 0.22 +/- 0.02 vs. 0.15 +/- 0.01, p < 0.05, respectively). LO also did not have an effect on ecNOS GE in aorta. In kidney, ecNOS GE was significantly increased in the LO group (from the beginning of the study) and two EP-treated groups compared with placebo., Conclusion: This study demonstrated that EP treatment significantly reduced SBP and UPE compared with placebo in both development and established 2K-1C renovascular hypertension. EP was as effective as LO in lowering the blood pressure of this renin-dependent animal model., (Copyright 2004 S. Karger AG, Basel)

The present study sought to determine whether myocardial fatty acid metabolism as assessed with iodine-123-labeled 15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) scintigraphy is impaired in patients with aortic valve disease (AVD) and whether the degree of the metabolic abnormality reflects the severity of AVD. BMIPP scintigraphy was performed in 12 patients with aortic stenosis (AS), 14 patients with aortic regurgitation (AR), and 9 healthy volunteers, and from that the heart-mediastinum uptake ratio (H/M ratio) corrected by the left ventricular (LV) mass (U/Mass ratio) and the myocardial washout rate (WR) were obtained. The H/M ratio tended to be higher in patients than in healthy volunteers (3.3 +/- 0.7 for AS, 3.5 +/- 0.5 for AR, 3.0 +/- 0.3 for healthy volunteers), and the WR was significantly higher in patients than in healthy volunteers (42.8 +/- 9.1% for AS, 35.7 +/- 6.5% for AR, 19.6 +/- 9.1% for healthy volunteers, p<0.01). In the AS patients, the U/Mass ratio showed significant negative correlations (r=-0.79 to -0.90, all p<0.01) and the WR showed significant positive correlations (r=0.61 to 0.82, all p<0.01) with transaortic pressure gradient, LV wall thickness, and LV mass. Similarly, in AR patients these BMIPP parameters showed proportional changes to the LV volumes and LV mass (r=-0.79 to -0.83, all p<0.01 for U/Mass ratio, r=0.55 to 0.70, p<0.05 to <0.01 for WR). In the 9 patients who underwent aortic valve replacement, the BMIPP parameters tended to normalize with increasing U/Mass ratio (0.90 +/- 0.41 x 10(-2)/g to 1.34 +/- 0.59 x 10(-2)/g, p<0.05) and decreasing WR (41.9 +/- 8.8% to 35.4 +/- 9.2%, p<0.01) after surgery. Myocardial fatty acid metabolism as assessed with BMIPP scintigraphy was impaired in patients with aortic valve disease and the U/Mass ratio and WR reflect the severity. These parameters may be useful for the noninvasive assessment of the myocardial metabolic abnormalities caused by hemodynamic overload.

Unlabelled: This study was designed to elucidate the usefulness of crosstalk correction for dual-isotope simultaneous acquisition (DISA) with 99mTc-tetrofosmin and FDG in estimating myocardial perfusion and viability., Methods: Eighteen patients with coronary artery disease were studied. First, SPECT was performed with a low-energy high-resolution collimator after a single injection of 99mTc-tetrofosmin (single 99mTc-tetrofosmin). Second, PET and DISA with an ultra-high-energy collimator were performed after glucose loading and an injection of FDG. DISA was designed to operate with simultaneous 3-channel acquisition, and weighted scatter correction of crosstalk from the 18F photopeak to the 99mTc photopeak was performed by modification of an existing dual-window technique. The FDG SPECT images were compared with the images obtained by PET. Both crosstalk-corrected and uncorrected 99mTc-tetrofosmin images were generated and compared with the single 99mTc-tetrofosmin images., Results: Regional percentage uptake of FDG agreed well between DISA and PET. However, regional percentage uptake of 99mTc-tetrofosmin was generally higher on the uncorrected 99mTc-tetrofosmin images than on the single 99mTc-tetrofosmin images, especially in areas of low flow (percentage count of 99mTc-tetrofosmin > or = 50%). The crosstalk correction contributed to improving the agreement between regional percentage uptakes and significantly improved the detectability of myocardial perfusion-metabolism mismatching., Conclusion: With 3-channel acquisition and weighted-scatter correction of crosstalk from the 18F photopeak to the 99mTc photopeak, DISA with 99mTc-tetrofosmin and FDG is feasible for assessing regional myocardial perfusion and viability.

Unlabelled: The diagnostic accuracy of cardiac FDG imaging obtained with the dual-head coincidence gamma camera (DHC) is impaired by artifacts induced by nonuniform attenuation. This study proposed a new method (registration and segmentation method for attenuation correction [AC-RS]) to correct these attenuations in the chest region without the need for additional hardware or expensive transmission scanning equipment., Methods: Before DHC imaging, 99mTc-tetrofosmin SPECT was performed using dual-energy acquisition from both the photopeak and Compton scatter windows. The scatter window images of the 99mTc-tetrofosmin were then registered 3-dimensionally with the cardiac DHC images and segmented into anatomic regions to obtain body and lung contours by applying the optimal threshold method on localized histograms. Theoretic attenuation coefficient values were assigned to the corresponding anatomic regions, and the DHC emission images were reconstructed using these attenuation correction factors. The results were quantitatively evaluated by imaging a cardiac phantom filled with a uniform solution and placed in a chest phantom. Eight nondiabetic subjects were also examined using this technique, and the results were compared with those of measured attenuation-corrected PET images., Results: Use of this technique in phantom and clinical studies decreased the degree of artifacts seen in the inferior wall activity and corrected the emission images. When the results were compared with those of PET scans, the regional relative counts of the uncorrected DHC scan did not correlate with the results of the PET scan. However, the regional relative counts of the AC-RS-corrected DHC scan exhibited a linear correlation with the results of the PET scan (r = 0.73; P < 0.001)., Conclusion: Reasonably accurate attenuation-corrected cardiac DHC images can be obtained using AC-RS without the need for transmission scanning.

Objective: To investigate the value of iodine-123 meta-iodobenzylguanidine (MIBG) myocardial imaging for defining high risk patients with idiopathic dilated cardiomyopathy from among candidates for beta blocker treatment, and for predicting functional improvement of the left ventricle in the early stages of treatment., Methods: Echocardiographic indices, neurohormonal measurements, and myocardial MIBG distribution were assessed at baseline and after one month and three months of treatment in 27 patients with idiopathic dilated cardiomyopathy. Patients were classified into two groups, based on whether they reached a daily dose of > 20 mg of metoprolol without deterioration of heart failure at three months (group A, n = 20) or not (group B, n = 7)., Results: There were no significant differences in the echocardiographic indices or neurohormonal activity at baseline between the two groups, but MIBG uptake was higher, and the washout rate lower, in group A than in group B. After one month, though there were no significant changes in echocardiographic and neurohormonal variables, the heart to mediastinal (H/M) ratio on the delayed image was increased in group A but not in group B. In group A, the degree of increase in the H/M ratio on the delayed image after one month was also correlated with the degree of reduction in plasma concentrations of noradrenaline after three months., Conclusions: MIBG myocardial imaging may be useful for predicting the outcome of beta blocker treatment for heart failure patients with idiopathic dilated cardiomyopathy.

First, we studied the diagnostic utility of myocardial imaging with 123I-BMIPP (BMIPP), a 3-methyl-branched fatty acid analog, in patients with various types of cardiomyopathy and left ventricular dysfunction (ejection fraction below 40%) by comparing with myocardial flow tracer imaging. The incidence of a dissociation between myocardial BMIPP and 201Tl distributions (BMIPP < 201Tl) as a marker of metabolic abnormality in viable tissue varied considerably among various heart diseases. Patients with ischemic cardiomyopathy and the dilated form of hypertrophic cardiomyopathy had a higher incidence while those with idiopathic dilated, alcoholic and hypertensive cardiomyopathy had a lower incidence. These results suggest that the marked difference between ischemic and idiopathic dilated cardiomyopathies may contribute to the differential diagnosis between these two diseases which are main basic abnormalities in congestive heart failure. Second, we investigated the relationship between myocardial BMIPP uptake and ventricular stress in patients with right ventricular pressure overload due to pulmonary hypertension. Myocardial BMIPP uptake in the right ventricle estimated by referring to uptake in the left ventricle showed a significant correlation with mean pulmonary artery pressure (mPAP) and no significant difference with myocardial 99mTc-sestamibi uptake in the 15-81 mmHg mPAP range. These results suggest that myocardial utilization of free fatty acid may be preserved in the presence of higher ventricular wall stress.

The transplanted heart is without autonomic nervous control in the early postsurgical period. We present here a case of cardiac transplantation in which 123I-metaiodobenzylguanidine (MIBG) SPECT and an exercise-loading test were used to monitor the sympathetic reinnervation. The distribution of myocardial 123I-MIBG uptake extended with time from 1 to 2 yr after surgery. However, functional improvement, estimated by the heart rate response to exercise, was not discernable during this period. The findings in this case suggest the feasibility of 123I-MIBG SPECT imaging in the serial monitoring of sympathetic reinnervation after transplantation and that scintigraphic evidence of reinnervation precedes functional recovery.

Objective: The present study was designed to determine the ability of positron emission tomography (PET) to assess myocardial viability and ischemia in acute myocardial infarction (MI) after reperfusion therapy (thrombolysis and/or coronary angioplasty)., Methods: PET with fluorine-18-labeled fluorodeoxyglucose (FDG) under fasting conditions and thallium-201 single-photon emission computed tomography (TL) were analyzed in 21 patients one week following MI. Myocardial viability was also assessed by regional wall motion using serial analysis of 2-D echocardiography or left ventriculography., Results: Marked uptake of FDG together with a residual perfusion defect were observed in the infarct region in all patients one week post MI. However, in 9 of the 21 patients, the infarct-related coronary artery had no significant stenosis after reperfusion therapy and remained patent in one month post MI suggesting no myocardial ischemia. In contrast, in 4 of the 21 patients the regional wall motion was akinetic and there was a complete defect observed with TL imaging at one month post MI, indicating no viability in the infarct region., Conclusions: PET using fasting FDG at one week post MI had a limitation to predict myocardial viability or ischemia.

To clarify the background of the scintigraphic improvement in non-gated myocardial perfusion imaging for patients with acute myocardial infarction, we performed serial ECG-gated 99mTc-MIBI myocardial SPECT in 17 patients with acute myocardial infarction (AMI) receiving successful reperfusion therapy. ECG-gated myocardial SPECT and left ventriculography were performed at 1 week (acute phase) and 1 month (subacute phase) after the onset of AMI. Regional %uptake (regional count x 100/maximal count) was determined for each of 8 myocardial segments of the Bull's eye map. We analyzed the data in 53 AMI segments out of total 136 myocardial segments, on the non-gated (NG), end-diastolic (ED), and end-systolic (ES) images. In addition, the delta %uptake (%uptake in subacute phase--%uptake in acute phase) was also determined as an index representing the improvement of myocardial tracer uptake on each image. In 17 segments (group A) with wall motion recovery assessed by serial left ventriculography, the %uptake on the NG image was significantly improved (61.6 +/- 10.0 to 75.7 +/- 10.1, p < 0.0001). However, in 36 segments (group B) without wall motion recovery, the change of %uptake on the NG image was small. There was no significant change in the %uptake on the ED image in groups A and B. On the contrary, the %uptake on the ES image showed a significant increase in group A (58.4 +/- 11.8 to 68.9 +/- 11.8, p < 0.001), but did not in group B. Thus, this change on the ES image reflects the wall motion recovery. Furthermore, in group A, there was a significant correlation between the delta %uptake on the NG image and those on the ES image (p < 0.02), but was not between those on the NG and the ED images. Thus, the change in the %uptake on the NG image was more related to those on the ES image which is more affected by the change in regional wall motion than those on the ED image which reflects improved myocardial perfusion. These results suggest that ECG-gated myocardial 99mTc-MIBI SPECT is more useful to assess the serial change in myocardial perfusion and contraction than the conventional non-gated SPECT in the follow-up study of patients with AMI.

In an investigation of myocardial metabolic abnormalities in hypertrophic myocardium, the myocardial glucose metabolism was evaluated with F-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) in 32 patients with hypertrophic cardiomyopathy, and the results were compared with those in 9 patients with hypertensive heart disease. F-18-FDG PET study was performed in the fasting and glucose-loading states. The myocardial regional %dose uptake was calculated quantitatively. The average regional %dose uptake in the fasting state in the patients with asymmetric septal hypertrophy and dilated-phase hypertrophic cardiomyopathy was significantly higher than that in the patients with hypertensive heart disease (0.75 +/- 0.34%, 0.65 +/- 0.25%, and 0.43 +/- 0.22%/100 g myocardium, respectively). In contrast, the average %dose uptake in the glucose-loading state in the patients with asymmetric septal hypertrophy and dilated-phase hypertrophic cardiomyopathy was not significantly different from that in patients with hypertensive heart disease (1.17 +/- 0.49%, 0.80 +/- 0.44% and 0.99 +/- 0.45%, respectively). The patients with apical hypertrophy had also low %dose uptake in the fasting state (0.38 +/- 0.21%) as in the hypertensive heart disease patients, so that the characteristics of asymmetric septal hypertrophy and dilated-phase hypertrophic cardiomyopathy are considered to be high FDG uptake throughout the myocardium in the fasting state. Patients with apical hypertrophy are considered to belong to other disease categories metabolically. F-18-FDG PET study is useful in the evaluation of the pathophysiologic diagnosis of patients with hypertrophic cardiomyopathy.

We studied the accuracy of left ventricular (LV) volumes and ejection fraction (EF) derived from ECG gated 99mTc-sestamibi myocardial perfusion SPECT (G-SPECT) and the software for automatic data analysis (QGS program described by Germano G et al.). G-SPECT was performed in 29 patients with various cardiac diseases. LV end-diastolic and end-systolic volumes (LVEDV and LVESV), and LVEF determined by QGS program were compared to those by Simpson method in biplane left ventriculography (LVG). Interobserver reproducibility in measuring the G-SPECT parameters was excellent (LVEDV: r = 0.99, LVESV: r = 0.99, LVEF: r = 0.97). There was a good correlation between the values obtained from G-SPECT and LVG (LVEDV: r = 0.92, LVESV: r = 0.94, LVEF: r = 0.85), but G-SPECT tended to underestimate LVEDV and LVEF. In 17 patients with moderate to severe myocardial perfusion defects selected from the subjects, the correlation was maintained fairly high (LVEDV: r = 0.90, LVESV: r = 0.92, LVEF: r = 0.77). In conclusion, QGS program provides high accuracy and reproducibility in determining LV volumes and LVEF from G-SPECT.

A 57-yr-old woman had frequent syncope when rising from a seated position. Her blood pressure fell from 140/80 mmHg to 60-70/40 mmHg while changing positions. Iodine-123-metaiodobenzylguanidine ([123I]MIBG) did not accumulate in the heart, whereas 201Tl-Cl (201Tl) did. Raise-up 99mTc-hexamethyl-propyleneamine oxime (99mTc-HMPAO) brain SPECT revealed decreased activity in the bilateral frontal areas, and subsequent supine 99mTc-HMPAO brain SPECT revealed filling in these areas, indicating that the cerebral blood flow (CBF) was transiently decreased in the frontal areas more than others in a standing position. The plasma norepinephrine (NE) level of this patient was normal during supine rest, but when she stood up, failure to increase the plasma level of NE uncovered a sympathetic nervous dysfunction. The CBF abnormality in patients with orthostatic hypotension may be due to a "functional" hemodynamic mechanism that induces orthostatic stress. This patient had transient hypoperfusion in the frontal areas when standing, without organic cerebral arterial stenosis. Only CBF in the frontal areas revealed relative hypoperfusion. These regions might be highly susceptible to a change in blood flow. The causes of orthostatic hypotension of this patient were autonomic failure with a disturbance of the sympathetic nerve endings, which was revealed by 99mTc-HMPAO brain SPECT and cardiac [123l]MIBG imaging.

To determine if imaging of blood flow (using 201Tl) and fatty acid (using 123-I-BMIPP) with SPECT can distinguish cardiomyopathy of coronary artery disease from nonischemic dilated cardiomyopathy, 24 patients with severe left ventricular dysfunction were evaluated. The origin of left ventricular dysfunction had been previously determined by coronary angiography to be ischemic (9 patients) or nonischemic (15 patients). Images were visually analyzed by three observers on a graded scale (score 0; normal, 1; mild uptake reduction, 2; severe uptake reduction, and 3; defect) in 20 left ventricular segments revealed higher defect score in ICM compared with NCM for 123I-BMIPP (35.5 +/- 14.4 versus 14.1 +/- 9.3, p <0.0005) and 201Tl (27.6 +/- 14.6 versus 12.1 +/- 7.4, p <0.005). The defect score/segment ratio also revealed higher value in ICM compared with NCM for 123I-BMIPP (2.25 +/- 0.52 versus 1.36 +/- 0.36, p <0.0001) and 201Tl (1.92 +/- 0.51 versus 1.24 +/- 0.42, p <0.005). Myocardium of ICM is more severely damaged than that of NCM. Thus, noninvasive SPECT imaging with 123I-BMIPP is helpful in distinguishing patients with severe left ventricular dysfunction secondary to coronary artery disease from those with nonischemic cardiomyopathy.

The right ventricle being primarily involved in ARVD, recent reports indicate the presence of histological and functional abnormalities in the left ventricle for some patients with ARVD. The aim of this study was to evaluate the significance of myocardial sympathetic dysfunction as an early sign of left ventricular (LV) involvement by 123I-MIBG (MIBG) SPECT and to compare the findings with those of 201TlCl (Tl) SPECT, radionuclide left ventriculography, ultrafast computed tomography (UFCT), magnetic resonance imaging (MRI) and echo-cardiography in 10 patients (pts) with ARVD. MIBG defects in LV regions were detected in 9 pts. Seven of the 9 pts showed MIBG defects in LV regions adjacent to RV. The subjects were divided into 2 groups based on left ventriculography, 5 with normal LVEF (> 55%) and 5 with reduced LVEF. In the normal LVEF group, 4 pts showed MIBG defects and 2 pts showed TI defects, and MIBG defects were larger than TI defects (ES: 14 +/- 6 vs. 5 +/- 7, p <0.05). In reduced LVEF group, all of 5 pts showed MIBG and TI defects, and MIBG defects were larger than TI defects (ES: 42 +/- 12 vs. 25 +/- 3, p <0.05). In comparison with normal LVEF group, reduced LVEF group showed larger and more severe MIBG defects (ES: 42 +/- 12 vs. 14 +/- 6, p <0.01, SS: 44 +/- 31 vs. 8 +/- 7, p <0.05). UFCT and MRI showed abnormal findings indicating LV fatty infiltration in only 3 of reduced LVEF group. Thus, MIBG showed abnormal distributions in the left ventricle with the highest frequency in all these modalities. These results suggest that MIBG SPECT provides a sensitive marker for detecting LV involvement in ARVD. Also, the extent of MIBG distribution abnormalities is helpful in assessing the severity of left ventricular involvement in patients with ARVD.

Visual interpretation of 123I-BMIPP (BMIPP) myocardial images has difficulties in detecting mild reduction in tracer uptake. We studied the significance of the objective assessment of myocardial BMIPP maldistributions at rest by using a Bull's-eye map and its normal data file for detecting ischemic heart disease. Twenty nine patients, 15 with prior myocardial infarction and 14 with effort angina were studied. The initial 15-min BMIPP image was evaluated by visual analysis and by generating the extent Bull's-eye map which exhibits regions with reduced % uptake under mean-2SD of 10 normal controls. The sensitivity for determining coronary lesions in non-infarcted myocardial regions with the extent map was superior to that with visual analysis (67% vs. 33%). In the regions supplied by the stenotic coronary artery, those which showed visually negative but positive in the map and which showed positive in both had higher incidence of wall motion abnormalities and severe coronary stenosis than those with normal findings in both. These results suggest that the objective assessment based on the normal data file in a Bull's-eye polar map is clinically important for improving the limitation of the visual interpretation in 123I-BMIPP imaging.

To characterize regional cardiac sympathetic dysfunction due to myocardial ischemia, we examined 123I-metaiodobenzylguanidine (MIBG) myocardial distribution of initial 15-min and 4-hr delayed SPECT images in 14 patients with recent myocardial infarction (MI), 25 patients with vasospastic angina which was angiographically proven with elgonovine maleate (Gp VSAP) and 16 patients with chest pain syndrome and normal CAG findings (GpCP). In those with MI, the study was serially done at 2 weeks after (Gp MI-1) and at 3 months after the onset of MI (Gp MI-2). We estimated regional tracer uptake in 20 segments of tomographic images by using a 4-point scoring system (0 = normal, 1 = mild, 2 = moderate, 3 = severe reduction) and calculated the total defect score (IDS). In all patients with MI, the area of reduced MIBG uptake was more extensive than the 201Tl perfusion defect in the acute stage (Gp MI-1) indicating the presence of viable but denervated myocardial tissue. Also, the MIBG defect was persistently observed from initial (TDS: 24 +/- 13) to delayed imaging (TDS: 26 +/- 12). However, in the chronic stage (Gp MI-2), the initial MIBG uptake improved (TDS: 18 +/- 9) but the delayed uptake remained almost the same (TDS: 22 +/- 10) indicating high washout of MIBG from the ischemic myocardium. Fourteen in Gp VSAP and 14 in Gp CP showed the regional MIBG defect in the delayed image more extensively than in the initial image indicating high washout of MIBG in the involved myocardial regions. These results suggest that neuronal uptake of MIBG is impaired in the acute stage of MI although neuronal retention of MIBG is predominantly impaired in the chronic stage of MI or in Gps VSAP and CP.

The authors studied 75 nonselected patients (30 men and 45 women; mean age 48 years) with sarcoidosis retrospectively to assess the applicability of nuclear examinations for detecting myocardial involvement. All patients were studied with Tl-201 myocardial perfusion scan (TMPS), Ga-67 myocardial scan (GMS), and left ventricular ejection fraction (LVEF) using ECG-gated radionuclide ventriculography. The positive GMS group had a significantly higher occurrence of abnormality on TMPS (100%) than the negative GMS group (41%). Patients with TMPS abnormality and positive GMS showed significantly lower LVEF (36.3%) than those of normal perfusion or negative GMS. When LVEF decreased, occurrences of TMPS abnormality and positive GMS increased. The authors demonstrate that in patients with sarcoidosis LVEF was closely related to TMPS and GMS, and LVEF reflected the progression of sarcoid heart disease and can be considered a reliable indicator of cardiac function. Patients with sarcoidosis with TMPS abnormality and positive GMS should be thought to have myocardial sarcoidosis and their cardiac functions can be assessed by ECG-gated radionuclide ventriculography, while the remaining patients should be examined with TMPS and GMS periodically for detection of myocardial involvement.

Myocardial washout of the new myocardial perfusion imaging agent, 99mTc-hexakis-2-methoxy isobutyl isonitrile (99mTc-MIBI) was studied in 23 patients with coronary artery disease. These patients were divided into three groups; 8 patients with effort angina pectoris (AP group), 6 with myocardial infarction who had reversible defect (MI-RD (+) group) and 9 with myocardial infarction who had not reversible defect (MI-RD (-) group). Regional radioactivities were determined with postexercise 1- and 3-hour myocardial planar images. In AP group, 99mTc-MIBI washout rate in ischemic area was smaller than in normal area (3.8 +/- 7.5% vs. 8.3 +/- 5.6%, p < 0.05), however, in the remaining two groups, there were no difference in washout between normal and infarct areas. Defect/normal ratios from postexercise 1 hour to 3 hours were slightly increased in AP and MI-RD (+) groups. Our results indicate that 99mTc-MIBI showed slight and incomplete myocardial redistribution in ischemic areas. These data showed to be considered in the interpretation of 99mTc-MIBI myocardial imaging.

To clarify the usefulness of the combined assessment of exercise (EX)-induced abnormalities in myocardial perfusion and regional wall motion for detecting coronary artery disease (CAD), we carried out first-pass radionuclide angiography and myocardial perfusion imaging during EX and at rest by 99mTc-tetrofosmin. Twenty-four patients with angiographically proven CAD, 9 (Gp A) with single and 15 (Gp B) with multivessel disease, were studied. The sensitivity for the detection of CAD was 78% of Gp A, 73% of Gp B in planar image and 78%, 87% in SPECT image, respectively. When left ventricular ejection fraction and regional ejection fraction (rEF) were combined with the result of myocardial perfusion, sensitivity increased up to 89% of Gp A, 100% of Gp B. Diagnostic accuracy of LAD, LCX and RCA was 79%, 88% and 83%, respectively. Regional EF in ischemic areas decreased during EX in both Gps, particularly in Gp B. Regional EF in relatively normal perfusion areas did not significantly change in Gp A, but decreased in Gp B. These results suggest that 99mTc-tetrofosmin contributes to the improvement of sensitivity for CAD by combined assessment of EX-induced wall motion and myocardial perfusion abnormalities.

To test the clinical significance of technetium-99m teboroxime regional myocardial clearance in the detection of coronary artery disease, 25 patients underwent dynamic planar or single-photon emission tomographic (SPET) myocardial imaging with 99mTc-teboroxime after exercise and again 2 h later at rest. All patients underwent both thallium-201 exercise and redistribution SPET and coronary arteriography. The early phases of exercise 99mTc-teboroxime myocardial clearance determined by dynamic planar imaging showed a significant difference between normal and post-stenotic myocardial regions (clearance rate constant k: 0.047 +/- 0.005 min-1 versus 0.034 +/- 0.003 min-1, P < 0.001). Reflecting this "differential clearance" between myocardial regions, an early redistribution-like phenomenon was observed in a significant number of myocardial segments by comparing serially acquired post-exercise 99mTc-teboroxime SPET images. These results indicated that the analysis of 99mTc-teboroxime myocardial clearance was of potential use in the detection of coronary artery disease, yielding additional information to that provided by the tracer distribution analysis. Although the early redistribution-like phenomenon of 99mTc-teboroxime could be the source of underestimation of ischaemia if acquisition of the initial post-exercise image were delayed, it could also prove useful in the early differentiation of ischaemia from scar because when the phenomenon was observed in delayed post-exercise images, the rest study could be omitted under some circumstances.

The detectability of coronary diagonal (Dx) branch disease in 24 patients (16 with myocardial infarction, 8 with angina pectoris; mean age of 56) with other branch (left anterior descending branch [LAD], left circumferential branch [LCX], or right coronary artery [RCA]) diseases was reviewed with 201TlCl exercised myocardial planar and SPECT images. In Dx branch disease with LAD #7 lesion (n = 10), Dx perfusion abnormality was detected in planar and SPECT images in 3 (30%) and 8 patients (80%), respectively. In Dx branch disease with LCX lesion (n = 7), Dx perfusion abnormality was detected in planar and SPECT images in 3 (43%) and 4 patients (57%), respectively. In Dx branch disease with RCA lesion (n = 7), Dx perfusion abnormality was detected in only 1 (14%) and 2 patients (29%), respectively. In conclusion, SPECT is a useful modality for detecting Dx branch disease, but it is sometimes hard to detect Dx branch disease with LCX and RCA lesions.

123I-MIBG (MIBG) regional defects in myocardial regions with preserved 201Tl (Tl) uptake have been observed in patients with idiopathic dilated cardiomyopathy (DCM). To evaluate whether the presence of Tl/MIBG mismatched regions is related to the occurrence of ventricular tachycardia (VT), we performed myocardial dual SPECT imaging with Tl (111 MBq) and MIBG (111 MBq) in 17 patients with DCM, 11 (Gp A) with and 6 (Gp B) without VT. Myocardial dual SPECT imaging was performed at 15 minutes after and 4 hours after the tracer injection. The regional tracer uptake was scored visually in 6 segments of the basal, middle, and apical short-axial images and in 2 apical segments of the midventricular vertical long-axial image by a four-point scoring system (0 = normal, 1 = moderate, 2 = severe and 3 = complete defect). Then, the severity of tracer maldistributions was assessed by the difference between total defect scores (TDSs) of Tl and MIBG (delta TDS). TDS was not different between Gps A and B in both Tl and MIBG images. However, delta TDS was larger in Gp A than in Gp B (13.5 +/- 6.5 vs. 5.8 +/- 3.0, p < 0.05). Also, the number of segments with the mismatched tracer uptake was larger in Gp A than in Gp B (12.5 +/- 3.0 vs. 8.3 +/- 1.5, p < 0.01). In the electrophysiologic study, we found that the fractionated area corresponded to the mismatched region in 3 of 5 patients in Gp A. These results suggest that regional sympathetic denervation is a possible factor which provocates VT, and myocardial dual SPECT imaging with Tl and MIBG is a useful method for predicting VT in patients with DCM.

To assess whether regionally depressed myocardial uptake of beta-methyl-p-(123I)-iodophenyl-pentadecanoic acid (123I-BMIPP), is related to regional ventricular diastolic dysfunction in patients (pts) with hypertrophic cardiomyopathy (HCM), we carried out 123I-BMIPP myocardial SPECT and radionuclide ventriculography (RNV) at rest in 9 HCM pts (eight pts with asymmetric septal hypertrophy (ASH), and one patient with apical hypertrophy). The defects of 123I-BMIPP were semiquantitatively estimated by segmental analysis. Regional LV function was determined by sector analysis in RNV: regional peak filling rate (rPFR), regional time to peak filling rate (rTPFR), and early 1/3 filling rate (1/3 fil) were estimated in the LV septal and posterior sectors. Wall thickness was evaluated with M-mode echocardiography. As results, the defects of 123I-BMIPP myocardial SPECT, were found frequently in septal wall, but any defect was not recognized in all septum with significant hypertrophy. Also, the degree of septal hypertrophy was not significantly related to BMIPP defect score. However, the regional diastolic function (rPFR, rTPFR, 1/3 fil) in the septal lesions with 123I-BMIPP defects was decreased more than those without 123I-BMIPP defect in HCM. Furthermore, the relative regional diastolic dysfunction (the differences between rTPFR and 1/3 fil in the septum and in the posterior wall) was significantly related to BMIPP defect score. In conclusion, this results suggest that the decreased uptake of 123I-BMIPP is related to regional diastolic dysfunction more than wall hypertrophy.

99mTc-Teboroxime [Chloro[tris(cyclohexyldioxime)methaneboronic acid] (99mTc)technetium], a perfusion agent for myocardial imaging, has a distinct advantage over 201Tl because of its very high myocardial extraction and is a 99mTc compound ideal for gamma camera imaging. This agent also demonstrates rapid myocardial washout, which allows completion of exercise and rest imaging studies in a short interval (to 1 hour). However, the rapid washout necessitates the completion of image acquisition very quickly after injection and therefore may require nonconventional SPECT imaging. In this Phase II study we evaluate the safety and efficacy of 99mTc-Teboroxime to detect coronary artery disease by exercise and rest SPECT imaging in 38 patients with prior myocardial infarction, 31 patients with angina pectoris, and 4 patients with non-coronary cardiac diseases. The 99mTc-Teboroxime dose used was 370-740 MBq in each study. The findings were compared with coronary angiography or 201Tl exercise and redistribution SPECT. No significant adverse reactions or laboratory abnormalities attributable to 99mTc-Teboroxime were observed. The quality of SPECT images was optimal in 62.5% of all patients. The relatively large population of suboptimal cases (37.5%) was attributed to the delay of the start and prolongation of the image acquisition time. In 85.7% of patients whose imaging was started within 5 minutes and completed within 11 minutes after injection, optimal quality was observed. Thus, 99mTc-Teboroxime SPECT requires the rapid completion of image acquisition after injection to achieve optimal image quality. Abnormalities of 99mTc-Teboroxime distribution were detected in 97.1% and 62.1% of patients with prior myocardial infarction or angina pectoris, respectively. The concordance with coronary angiography was 84.4% and 68.0%, and with 201Tl was 78.1% and 74.1%, respectively. Although standardization of the image protocol suitable for this agent is needed for the next study, these high correlations suggest the potential usefulness of 99mTc-Teboroxime SPECT imaging.

Although blunted cardiac response to sympathetic stimulation in patients with heart failure is usually attributed to myocardial beta 1-adrenoceptor downregulation secondary to elevated circulating catecholamines, cardiomegaly per se may also play a role through presynaptic mechanisms such as reduction in cardiac norepinephrine (NE) concentration. To evaluate effects of cardiac dilatation on cardiac response to sympathetic stimulation, we studied left ventricular contractile and heart rate responses to plasma NE levels increased by exercise in 10 asymptomatic patients with a dilated left ventricle due to aortic regurgitation (AR), but with normal resting plasma NE levels, using 10 normal subjects and 10 patients with heart failure due to dilated cardiomyopathy (DCM) as controls. Plasma NE levels, systemic blood pressure, echocardiographic left ventricular dimensions, and heart rate were measured at rest, and at 3 submaximal levels of supine bicycle exercise. The ratio of peak systolic blood pressure to end-systolic dimension (P/D ratio), heart rate, and plasma NE increased with the intensity of exercise. In each subject, both P/D ratio and heart rate increased in a logarithmic manner against plasma NE levels. The slope of the regression line for log (plasma NE)--P/D ratio relation, and that for log (plasma NE)--heart rate relation, were significantly less in patients with AR than in normal subjects (p less than 0.001 and p less than 0.05, respectively), and were less in patients with DCM than in patients with AR (p less than 0.005 and p = 0.051, respectively). Thus, the left ventricular contractile and heart rate responses to sympathetic stimulation are blunted in patients with dilated hearts due to AR, even in the absence of overt heart failure and elevated plasma NE levels. These responses were further decreased in patients with heart failure due to DCM. Cardiac responses to sympathetic stimulation appear to be blunted by cardiac dilatation per se, independently of myocardial beta 1-receptor downregulation secondary to high circulating catecholamines. The decrease in mechanical response to sympathetic stimulation in failing hearts is likely to be combined result of cardiac dilatation and beta 1-receptor downregulation.

We studied the significance of I-123 MIBG (metaiodobenzylguanidine) myocardial scintigraphy for evaluating the severity of congestive heart failure. I-123 MIBG scintigraphy was performed in 7 patients with congestive heart failure (CHF) of NYHA class I-III (6 with dilated cardiomyopathy and 1 with Adriamycine cardiomyopathy) and in 2 normals. The SPECT and anterior planar myocardial images were obtained 15 minutes after (initial images) and 4 hours after (delayed images) an injection of I-123 MIBG (111 MBq). Compared with normals, patients with CHF demonstrated (1) low myocardial uptake and (2) rapid myocardial washout of I-123 MIBG, indicating myocardial sympathetic disarrangement. Then, quantitating these abnormalities with the heart to upper mediastinum uptake ratio (H/B) and the percent washout rate (%WR) during 4 hours, respectively, we compared these two indices with LV ejection fraction (EF) at rest measured by echocardiography and exercise capacity (max VO2 and VO2 at anaerobic threshold (AT] determined with respiratory gas exchange analysis during maximal bicycle exercise. H/B was lower and %WR was greater in patients with CHF than in normals. H/B correlated with EF (r = 0.77, p less than 0.05) and AT (r = 0.74, p less than 0.05). On the other hand, %WR significantly correlated with EF (r = 0.79, p less than 0.05), max VO2 (r = -0.74, p less than 0.05) and AT (r = -0.81, p less than 0.05). Thus, H/B and %WR were closely related to the severity of CHF. These results suggest that I-123 MIBG myocardial scintigraphy and the quantitative analysis of I-123 MIBG myocardial uptake provide useful information about the severity of CHF.

Regional denervation of adrenergic nerves has been clinically demonstrated in patients with myocardial infarction using I-123 metaiodobenzylguanidine (MIBG) scintigraphy. However, it is not clarified whether adrenergic denervation can be induced by prolonged myocardial ischemia as well as by myocardial infarction. This case with effort angina had 99% stenosis of right coronary artery and showed perfusion defects at inferior myocardial regions in the exercise thallium-201 study. However, inferior wall motion estimated by echocardiography and left ventriculography was normal indicating the absence of myocardial infarction. After percutaneous transluminal coronary angioplasty for the stenosis, I-123 metaiodobenzylguanidine (MIBG) and thallium-201 (Tl-201) myocardial scintigraphies were done to estimate the therapeutic effect of PTCA. Although the Tl-201 study during exercise showed normal findings indicating the success of PTCA, marked defects was detected at inferior myocardial regions in the I-123 MIBG studies just after and 4 hours after an intravenous injection of I-123 MIBG. These results suggest that adrenergic derangement may be induced by prolonged myocardial ischemia and may persist for periods even though myocardial perfusion is normalized.

To detect Adriamycin cardiomyopathy, radionuclide myocardial imagings with Tl-201, Tc-99m pyrophosphate, I-123 metaiodobenzylguanidine and Ga-67 were performed in a 49 year-old-woman receiving Adriamycin (a total dose of 230 mg/m2) for the treatment of breast cancer. This patient demonstrated symptoms of congestive heart failure 2 months after the last intravenous administration. At the period of performing the radionuclide studies, echocardiographic LV ejection fraction (EF) was 22%. Despite severe deterioration of cardiac function, Tl-201 SPECT demonstrated no defect and Tc-99m pyrophosphate (PYP) SPECT demonstrated no positive finding. I-123 metaiodobenzylguanidine (MIBG) scintigraphy demonstrated no regional defect. However, I-123 MIBG washout rate during 4 hours was markedly enhanced, probably reflecting abnormalities of norepinephrine kinetics due to the progression of heart failure. Compared to these pharmaceuticals, Ga-67 was diffusely accumulated in the heart. Then, 5 months after the first study, when LV EF improved to 30% and congestive symptoms disappeared probably owing to beta-blockade therapy, myocardial accumulation of Ga-67 markedly reduced. It has been reported that Ga-67 accumulates in malignant tumor cells and leukocytes. Since, in Adriamycin cardiomyopathy, myocardial accumulation of leukocytes with myocardial fibrotic changes have been histologically demonstrated, the results of Ga-67 scintigraphy may reflect the accumulation of leukocytes. Thus, this case indicates that Ga-67 scintigraphy is advantageous for detecting Adriamycin cardiomyopathy and may be more useful than Tl-201 and Tc-99m PYP scintigraphies.

To assess the impairment of early diastolic left ventricular (LV) filling and the effect of atrial contraction on total LV filling in patients (pts) with coronary artery disease (CAD), LV volume (LVV) changes during rapid filling (RF) and atrial contraction (AC) phases were studied by equilibrium radionuclide ventriculography in 10 normals (N) and 17 pts with CAD including eight without (CAD-1) and nine with (CAD-2) previous myocardial infarction (MI). The data were acquired in a list-mode fashion as a series of X, Y coordinates, time markers and an ECG's R wave (R) plus the second heart sound (S2) markers. LVV curves were obtained from three types of multi-gated images by (1) R-synchronized forward reformatting for the analysis of systolic phase (ejection fraction; EF and peak ejection rate; PER), (2) S2-synchronized forward reformatting for the analysis of RF phase (peak filling rate; PFR-RF and filling fraction; FF) and (3) R-synchronized backward reformatting for the analysis of AC phase (peak filling rate; PFR-AC and LVV increment with atrial contraction/stroke volume; AC/SV). EF and PER were significantly lower (p less than 0.001) in CAD-2 (36.0 +/- 8.1% and -1.5 +/- 0.4 EDV/sec) than in N (58.2 +/- 5.8% and -2.4 +/- 0.4 EDV/sec), but those in CAD-1 (52.7 +/- 6.4% and -2.2 +/- 0.3 EDV/sec) were almost the same as N. However PFR-RF and FF were reduced both in CAD-1 (1.5 +/- 0.4 EDV/sec and 23.0 +/- 7.0%) and CAD-2 (1.3 +/- 0.4 EDV/sec and 19.0 +/- 8.0%) compared with N (2.3 +/- 0.4 EDV/sec and 37.0 +/- 8.3%). PFR-AC and AC/SV were significantly greater (p less than 0.01) in CAD-1 (1.3 +/- 0.3 EDV/sec and 0.30 +/- 0.06) than N (0.8 +/- 0.3 EDV/sec and 0.13 +/- 0.07), but those in CAD-2 (0.6 +/- 0.4 EDV/sec and 0.18 +/- 0.09) showed no increase like in CAD-1. These results indicate that 1) the impairment of early diastolic filling precedes the evidence of systolic dysfunction in pts with CAD and 2) AC could compensate the impaired early filling in pts without prior MI, whereas in pts with prior MI this compensatory mechanism is absent presumably because of elevated LV filling pressure.

The electrocardiograms (ECGs) in five kinds of bipolar leads were recorded from the body surface of the carp under water. Each component constituting the ECG wave could be detected by the present method. The potentials of the ECGs recorded by the present method were relatively small, the values being 2-64 microV. The electrical axis in most carp was directed toward the right lateral side.

In the present study, we attempted to test the hypothesis that ejection timing rather than peak left ventricular pressure is a primary determinant of ventricular relaxation rate. In cross-circulated isolated canine hearts instantaneous left ventricular volume was controlled by a servo-pump system. To eliminate the effects of end-systolic and end-diastolic volumes and ejection velocity on left ventricular relaxation rate, these parameters were clamped, and only the ejection timing (onset and end of ejection) was altered, keeping the duration of ejection unchanged. Left ventricular relaxation rate was assessed by time constants of left ventricular pressure decline during the isovolumic relaxation phase calculated by both a semilogarithmic method, assuming that the asymptote is zero, and a best exponential fitting method. In 25 runs, a pair of contractions with ejection timings which differed by 53.1 +/- 2.1 (SE) msec were imposed, while end-systolic and end-diastolic left ventricular volumes and ejection duration were unchanged. All pairs of contractions demonstrated early ejection resulted in significantly (P less than 0.001) slowed relaxation as indicated by a prolongation of the time constants of isovolumic left ventricular pressure decay (delta 4.2 +/- 0.7, sec and delta 15.4 +/- 2.1 msec by semilogarithmic plot and the best exponential fit respectively), although peak left ventricular pressures (104.6 +/- 2.4 mm Hg) were even lower than those (116.6 +/- 2.8 mm Hg) in contractions with later ejection timing. Furthermore, in seven experiments, the heart was allowed to eject at five different timings; onset and end of ejection were progressively delayed in steps of 20 or 30 msec.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrioventricular (AV) delay that results in maximum ventricular filling and physiological mechanisms that govern dependence of filling on timing of atrial systole were studied by combining computer experiments with experiments in the anesthetized dog instrumented to measure phasic mitral flow. Ventricular filling volume is maximized at AV delay of 100 ms in the computer study and 80 ms in the dog study. At any time in diastole atrial contraction accelerates mitral flow, opening the mitral valve widely; atrial relaxation then decelerates mitral flow, moving the valve leaflets toward closure. The time the valve remains closed following atrial systole varies inversely with AV delay. When AV delay is optimal, the mitral valve is moving rapidly toward closure but is not yet closed at onset of ventricular systole. The decline in filling volume as AV delay decreases below its optimum value is primarily the result of premature termination of atrial ejection by ventricular systole. As AV delay increases above its optimal value, filling volume progressively decreases because of premature mitral valve closure that limits effective diastolic filling period. There is no significant retrograde mitral flow at any point in diastole for any AV delay.

Peak rapid filling rate (PRFR) is often used clinically as an index of left ventricular relaxation, i.e., of early diastolic function. This study tests the hypothesis that early filling rate is a function of the atrioventricular pressure difference and hence is influenced by the left atrial pressure as well as by the rate of left ventricular relaxation. As indexes, we chose the left atrial pressure at the atrioventricular pressure crossover (PCO), and the time constant (T) of an assumed exponential decline in left ventricular pressure. We accurately determined the magnitude and timing of filling parameters in conscious dogs by direct measurement of phasic mitral flow (electromagnetically) and high-fidelity chamber pressures. To obtain a diverse hemodynamic data base, loading conditions were changed by infusions of volume and angiotensin II. The latter was administered to produce a change in left ventricular pressure of less than 35% (A-1) or a change in peak left ventricular pressure of greater than 35% (A-2). PRFR increased with volume loading, was unchanged with A-1, and was decreased with A-2; T and PCO increased in all three groups (p less than .005 for all changes). PRFR correlated strongly with the diastolic atrioventricular pressure difference at the time of PRFR (r = .899, p less than .001) and weakly with both T (r = .369, p less than .01) and PCO (r = .601, p less than .001). The correlation improved significantly when T and PCO were both included in the multivariate regression (r = .797, p less than .0001). PRFR is thus determined by both the left atrial pressure and the left ventricular relaxation rate and should be used with caution as an index of left ventricular diastolic function.

For determining an indication of percutaneous transluminal angioplasty (PTCA), a 73-year-old-man with silent ischemia and with ventricular premature complexes (quadrigeminy) were performed cardiac nuclear studies. This case had 99% stenosis in LCX (#11) and 90% stenosis in RCA (#1), and demonstrated akinetic wall motion in left ventricular (LV) inferior and posterior regions. Exercise-redistribution Tl-201 studies indicated myocardial viability in a portion of the inferior wall but not in the posterior wall. To estimate the potential contractile function in the regions with akinesis, from the list-mode data of radionuclide ventriculography, those of postsinus beats and postextrasystolic beats were separately selected and were analyzed for investigating LV wall motion and LV ejection fraction (EF). With the post-extrasystolic potentiation, LVEF increased from 36% to 45% and the systolic wall motion was augmented in the inferior wall but not in the posterior wall. From these findings we recognized the existence of myocardial viability in a portion of the inferior wall. After PTCA for the RCA lesion, improvements of the myocardial Tl-201 distribution and LV wall motion in the inferior wall were definitely observed and hence LVEF increased by 16% to contribute to an increase in exercise performance. Thus, this case indicates that the postextrasystolic potentiation is useful for determining an indication of PTCA in patients with LV asynergy, demonstrating the myocardial viability and the potential LV function.

The accuracy of left ventricular ejection fractions (EF) determined by multiple gated cardiac pool imaging (RI-EF) and by M-mode echocardiography (Echo-EF) (Teichholz's method) was evaluated by comparing with those derived from angiocardiography (LVG-EF) in 19 patients including 9 with myocardial infarction, 3 with rest angina, 2 with effort angina, 2 with valvular disease, 1 with hypertrophic cardiomyopathy, 1 with congestive cardiomyopathy and 1 with hypertensive heart. Measurement of RI-EF was carried out by the fixed ROI method using a single end-diastolic ROI, and the variable ROI method where end-diastolic and end-systolic ROI were used.

To elucidate the role of loading sequence in afterload-dependent slowed relaxation in hearts in situ, the time constants (Texp from best exponential fitting method and TL from semilogarithmic method) of isovolumetric left ventricular (LV) pressure decay were studied in nine anesthetized open-chest dogs under the pharmacological blockade of autonomic nerve activity. An afterload change was imposed by clamping the ascending or descending aorta to make the peak LV pressure early or late in systole. During afterload interventions, in contractions with the peak LV pressure in late systole Texp and TL were significantly (P less than 0.05) larger than in those with the peak LV pressure in early systole in any comparable peak LV pressure range. Moreover, both time constants were directly correlated (P less than 0.01) with the time of peak LV pressure irrespective of peak LV pressure and clamp mode of aorta. In another protocol, marked differences both in Texp and TL were also observed between each of 25 pairs of contractions with different loading sequence but with comparable peak LV pressure and LV dimension (segment length). Thus afterload-dependent slowed relaxation in hearts in situ could not be attributed to an increased total load but to the altered loading sequence associated with an increase in afterload.

To validate the significance of technetium-99m-pyrophosphate (Tc-99m PYP) myocardial scintigraphy in diagnosing cardiac amyloidosis, 2 patients with familial amyloid polyneuropathy (FAP) and 1 patient with amyloidosis secondary to chronic rheumatic arthritis were studied. All three patients had echocardiographic abnormalities, which were increased wall thickness of the interventricular septum and the left ventricular posterior wall, and granular sparkling appearance in the septum. In 2 patients with FAP, abnormal myocardial uptake of Tc-99m PYP was diffusely detected in Tc-99m PYP SPECT. In the remaining 1 patient with secondary amyloidosis, however, Tc-99m PYP SPECT showed no abnormality, although we had confirmed the presence of myocardial amyloid deposits (type AA amyloid protein) with high amount in the histological examination. Thus, these results indicate that Tc-99m PYP scintigraphy may have a limitation in detecting cardiac involvement in secondary amyloidosis although it is useful in FAP.

The long-axis (L-A) tomograms of the heart in thallium-201 SPECT have been conventionally reconstructed as those parallel to the midventricular vertical or horizontal L-A plane. We developed a new algorithm for reconstructing the rotated L-A tomograms around the L-A to longitudinally observe thallium-201 myocardial distribution and to provide an optimal view of the cardiac apex. After determining the orientation of the L-A and reconstructing the short-axis (S-A) tomograms using standard techniques, the coordinates of the S-A planes were transformed to the polar coordinates whose origin is located at the position of the L-A in each plane. Then, "radial L-A tomograms", i.e. midventricular L-A planes oriented at the angle of every 6 degrees to the midventricular horizontal L-A plane, were reconstructed. Also, we developed a new technique for analyzing thallium-201 distribution of the L-A tomograms. For the basal 2/3 regions, two profiles which consist of the pixels with maximum count on the upper and lower myocardial portions of the lines (spaced at 1 pitch) vertically to the L-A were computed. For the remaining apical 1/3 regions, the semi-circumferential maximum-count profile from the values of 30 radii spaced at 6 degrees interval were computed. Based on these profiles, a 2D polar representation was then generated. From the study using a cardiac phantom with an apical small infarction, the usefulness of this new tomographic method for the detection of apical myocardial ischemia was demonstrated. The application to the exercise/redistribution studies in patients with effort angina indicated that radial long-axis tomography provides precise information about the longitudinal extent of perfusion defects, particularly in the apical regions.

Objective: To determine whether concentrations of heart-type fatty acid binding protein (H-FABP) measured before hospital discharge predict critical cardiac events in patients with idiopathic dilated cardiomyopathy (DCM). Patients: 92 consecutive patients with DCM were enrolled and followed up for four years. Main outcome measures: Serum concentrations of H-FABP, brain natriuretic peptide (BNP), cardiac troponin T before hospital discharge and survival rate. Results: 23 patients died of cardiac causes, received a left ventricular assist device or underwent heart transplantation during the four-year follow up. Univariate analyses showed that New York Heart Association functional class, heart rate, ejection fraction, serum H-FABP and plasma BNP were significant variables. According to multivariate analysis, serum H-FABP and plasma BNP concentrations were independent predictors of critical cardiac events. Cardiac troponin T before hospital discharge was not a predictor. The area under the receiver operating characteristic curve for death from critical cardiac events was similar between H-FABP and BNP. Patients with an H-FABP concentration at or above the median (⩾ 5.4 ng/ml) had a significantly lower survival rate than those below the median, according to analysis by log rank test (p < 0.0001). When combined with BNP concentration at or above the median (⩾ 138 pg/ml), H-FABP below the median predicted the worst prognosis among the combinations. Conclusions: The concentration of serum H-FABP before discharge from hospital may be an independent predictor for critical cardiac events in DCM. [ABSTRACT FROM AUTHOR]