Search

To evaluate the hemodynamic impact of coronary stenoses, the fractional (FFR) or coronary flow velocity reserve (CFVR) usually is measured. The combined measurement of instantaneous flow velocity and pressure gradient (v-dp relation) is rarely used in humans. We derived from the v-dp relation a new index, dp(v50) (pressure gradient at flow velocity of 50 cm/s), and compared the diagnostic performance of dp(v50), CFVR, and FFR. Before coronary angiography was performed, patients underwent noninvasive stress testing. In all coronary vessels with an intermediate or severe stenosis, the flow velocity, aortic, and distal coronary pressure were measured simultaneously with a Doppler and pressure guidewire after induction of hyperemia. After regression analysis of all middiastolic flow velocity and pressure gradient data, the dp(v50) was calculated. With the use of the results of noninvasive stress testing, the dp(v50) cutoff value was established at 22.4 mmHg. In 77 patients, 124 coronary vessels with a mean 39% (SD 19) diameter stenosis were analyzed. In 43 stenoses, ischemia was detected. We found a sensitivity, specificity, and accuracy of 56%, 86%, and 76% for CFVR; 77%, 99%, and 91% for FFR; and 95%, 95%, and 95% for dp(v50). To establish that dp(v50) is not dependent on maximal hyperemia, dp(v50) was recalculated after omission of the highest quartile of flow velocity data, showing a difference of 3%. We found that dp(v50) provided the highest sensitivity and accuracy compared with FFR and CFVR in the assessment of coronary stenoses. In contrast to CFVR and FFR, assessment of dp(v50) is not dependent on maximal hyperemia.

A system for analyzing left ventricular (LV) electromechanical asynchrony based on transesophageal 3-dimensional echocardiography (3-DE) and semi-automatic endocardial contour detection is described. Eighteen consecutive patients underwent 3-DE. Using TomTec 4DLV software, a 3-dimensional endocardial surface was reconstructed throughout the cardiac cycle. Matlab software generated color-coded polar maps, displaying regional LV displacement and its timing. At the segmental level, Bland-Altmann assessment showed intraobserver variability of LV displacement of 0.1 +/- 3.0 mm and timing of -5.6 +/- 160 ms (bias +/- 2 SD) for all segments and -1.6 +/- 94 ms for the nonapical segments. The combination of 3-DE and semi-automatic contour detection is feasible and provides unique information for assessing regional LV endocardial displacement and electromechanical asynchrony.

Background: High admission blood glucose levels after acute myocardial infarction (AMI) are common and associated with an increased risk of death in subjects with and without known diabetes. Recent data indicate a high prevalence of abnormal glucose metabolism in patients with unknown diabetes at the time of AMI. We investigated the predictive value of admission blood glucose levels after AMI for long-term prognosis in patients with and without previously diagnosed diabetes mellitus, particularly in those with unknown diabetes but with blood glucose levels in the diabetic range., Methods: In a retrospective study with prospective follow-up, 846 patients (737 without and 109 with known diabetes) were eligible for follow-up during a median of 50 months (range, 0-93 months)., Results: During follow-up, 208 nondiabetic patients (28.2%) and 47 diabetic patients (43.1%) died (P =.002). An increase of 18 mg/dL (1 mmol/L) in glucose level was associated with a 4% increase of mortality risk in nondiabetic patients and 5% in diabetic patients (both P<.05). Of the 737 previously nondiabetic subjects, 101 had admission blood glucose levels of 200 mg/dL (11.1 mmol/L) or more, and mortality in these patients was comparable to that in patients who had established diabetes (42.6% vs 43.1%)., Conclusions: Admission blood glucose level after AMI is an independent predictor of long-term mortality in patients with and without known diabetes. Subjects with unknown diabetes and admission glucose levels of 200 mg/dL (11.1 mmol/L) or more after AMI have mortality rates comparable to those of subjects with established diabetes. Admission blood glucose level may serve to identify subjects at high long-term mortality risk, in particular among those with unknown diabetes.

Background: Little is known about the differences between the corrected thrombolysis in myocardial infarction (TIMI) frame count (CTFC) and the 'frame count velocity' (FCV), an estimate of blood flow velocity derived from the TFC and the length of the related vessel, in each of the three epicardial coronary arteries., Methods: After angioplasty of 119 coronary vessels, 50 left anterior descending (LAD), 27 left circumflex (LCX) and 42 right coronary arteries (RCA), the CTFC was compared with the FCV assessed by measuring the length of the coronary arteries with an intracoronary guidewire., Results: The three vessels show a significant difference in mean length (the LAD was 14.5±1.6 cm, LCX 12.8±1.9 cm and RCA 11.3±1.4 cm, p<0.001 for all comparisons), making it possible to convert the TFC to the FCV with reasonable accuracy without having to use a guidewire. The mean length of the LCX and the RCA was found to be considerably longer than in previous reports on which the CTFC is based. In addition, with this method the estimation of the coronary blood flow velocity in the RCA is significantly higher compared with the LAD and LCX (23.0±7.9 cm/sec versus 17.6±7.4 cm/sec and 16.4±6.3 cm/sec, respectively, p<0.001)., Conclusion: With the TFC and the average length of the related coronary artery presented in this study, the FCV can be calculated for each of the three vessels resulting in a simple and, compared with the CTFC, more accurate angiographic estimation of the coronary blood flow velocity.

Objectives: We assessed the feasibility and reproducibility of the instantaneous diastolic coronary flow velocity-pressure gradient relation to characterize different degrees of coronary stenoses., Background: Assessment of the hemodynamic significance of coronary stenoses can be difficult. Using sensor-tipped guidewires, various physiologic indexes can be determined in the catheterization laboratory. Each of the current methods, however, has limitations., Methods: After positioning a Doppler flow wire and a pressure wire distal of a coronary stenosis, the flow velocity signals and the proximal and distal pressure were sampled simultaneously, at baseline and after intracoronary administration of adenosine. The instantaneous diastolic flow velocity and pressure gradient of single cardiac cycles at baseline, at maximal and intermediate hyperemia were plotted. Data were fitted with a regression line using the equation: Delta P = 0 +kv+Sv(2). Measurements were performed in 11 normal coronary arteries, 20 intermediate stenoses and in 7 severe stenoses before and after percutaneous transluminal coronary angioplasty plus stenting., Results: We found significant differences between normal coronary arteries, intermediate and severe stenoses. Percutaneous transluminal coronary angioplasty nearly normalized the highly abnormal flow-pressure gradient relation in the severe stenoses. A high degree of reproducibility was observed. In 3% of the measurements, analysis was not possible due to the occurrence of pressure drift or bad flow velocity signals., Conclusions: It is feasible to assess the diastolic flow velocity-pressure gradient relation over a wide range of stenoses. It characterizes the hemodynamics of epicardial coronary stenoses and allows discrimination between normal coronary arteries, intermediate and severe stenoses.

Background: With the increasing use of cineless diagnostic angiography laboratories, modern telecommunication networks provide an excellent opportunity to transfer dynamic cardiac catheterisation images from a referring centre to a cardiac intervention centre. This electronic data transfer may lead to improved patient care and reduced waiting times., Methods: Two departments of cardiology started a pilot project using a digital ISDN-30 point-to-point data-line connection between Alkmaar and Amsterdam over which MPEG compressed angiograms are sent. The network consists of a PC based client/server structure and two ISDN modular routers., Results: From June 1998 to January 2001, 127 patients were referred for urgent PTCA or CABG using this network. All patients were admitted to the CCU for unstable angina and had a suitable anatomy for coronary angioplasty or coronary artery bypass surgery. In all cases the MPEG compressed images were successfully stored on the server and could be accessed in Amsterdam. During the pilot phase all X-ray runs (11 + 3) were sent. Following transmission, all patients were accepted for intervention. Review of the DICOM images from the CD-Medical immediately before the PTCA or CABG did not change the planned strategy. The patients were successfully treated 1 to 2 days after data transmission. During this phase, the average variable costs of this network was € 5.90 per patient as opposed to € 69.00 when using a courier service., Conclusion: This study shows that personal computer-based telecommunication network systems are feasible for clinical use in daily practise. Access to a remotely located cardiac intervention centre can be achieved promptly at low costs and improves patient care by reducing waiting times.

Electromagnetic interference of pacemaker systems has been well established and can lead to an inappropriate function of these devices. Recently, an implantable loop recorder (ILR) (REVEAL, Medtronic Inc.) has been introduced to evaluate the possible arrhythmic etiology of patients with recurrent syncope. We evaluated the interference of this device in two patients with implantable ILR and in three nonimplanted ILRs with four electromagnetic sources: cellular phones (GSMs), electronic article surveillance systems (EASs), metal detector gates (MDGs), and magnetic resonance imaging (MRI). The GSM did not affect appropriate function of the ILR whereas radiofrequency (RF) EAS could interfere with normal function in implanted and nonimplanted systems. The MDG had no influence on ILR function. The magnetic field induced by the MRI resulted in an irreversible error in one nonimplanted ILR. Therefore, although interference between electromagnetic sources and ILRs appears to be rare in our study, physicians should be aware of possible malfunctioning of these devices.