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Aims: Mitral isthmus (MI) ablation is technically challenging, requiring long endocardial ablation times and frequently coronary sinus (CS) ablation. The circumflex artery lies in the epicardium in close proximity to the CS and the mitral annulus and may potentially be injured during radiofrequency ablation., Methods and Results: Fifty-four patients underwent catheter ablation procedures that included MI ablation for treatment of atrial fibrillation. Irrigated ablation catheters were used with the following settings: endocardial surface (max power: 40/50 W at the annular end; max temperature: 48°C); CS (max power: 25/30 W; max temperature: 48°C). Coronary angiography was performed pre- and post-ablation and analysed by two cardiologists with quantitative coronary angiography. Mitral isthmus block was achieved in 89% of patients (60% required CS ablation). Fifteen patients (28%) had angiographic changes following ablation: eight had mid-circumflex narrowing only, one had circumflex and obtuse marginal (OM) artery narrowing, one had OM narrowing only, and five had distal circumflex occlusion/narrowing. Five patients had significant narrowing (50-84%), which resolved with intracoronary glycerine trinitrate. Fourteen (93%) of the patients with circumflex 'injury' had CS ablation and a longer mean CS ablation time (5.0 ± 3.0 vs. 2.6 ± 3.3 min, P = 0.03). Patients with distal circumflex occlusion had significantly smaller vessel diameter (1.0 ± 0.1 vs. 2.1 ± 0.2 mm, P = 0.03). A shorter distance between the circumflex and the CS was also associated with circumflex 'injury' (3.2 ± 1.9 vs. 5.6 ± 3.2 mm, P = 0.04). There were no electrocardiographic or echocardiographic abnormalities and no angina symptoms during follow-up., Conclusion: Acute sub-clinical circumflex 'injury' following MI ablation is not uncommon. Ablation within the CS, proximity of the circumflex and the CS, and a small distal circumflex were risk factors for 'injury'.

Introduction: Little is known about the incidence and timing of reactive pericardial collections developing after left atrial catheter ablation (LACA), and when and if transthoracic echocardiography (TTE) should be performed routinely in these patients postprocedure., Methods and Results: Two hundred consecutive LACA patients for persistent atrial fibrillation (AF) (107), paroxysmal AF (75) or atrial tachycardia (AT) (18) underwent on-table TTE at the end of the procedure, and the next day prior to discharge. One patient developed tamponade at the time of transseptal puncture. Thirty-three percent of the remaining 199 who underwent on-table TTE, had a pericardial collection. On next day TTE, there were significantly more pericardial collections (53%, P < 0.0001). Persistent rather than paroxysmal arrhythmia at the time of the procedure was the only predictor of a pericardial collection, either on-table (χ(2)= 9.64; P = 0.002) or next day (χ(2)= 5.95; P = 0.02). Eight patients had collections on next day TTE ≥ 1.5 cm. One needed drainage because of clinical tamponade. Repeated TTEs in the other 7 patients demonstrated resolution of collections over 1-2 weeks., Conclusion: Pericardial collections are common in LACA patients. Almost all are not associated with clinical compromise. The only predictor of collection size is arrhythmia type at ablation, which may correspond to ablation at sites specific to persistent rather than paroxysmal arrhythmias. Performing on-table TTE routinely may help guide immediate anticoagulation protocols, but even larger on-table collections are not associated with tamponade and resolve spontaneously. TTE does not need to be performed routinely unless there are clinical signs of tamponade., (© 2011 Wiley Periodicals, Inc.)

Background: Mitral isthmus ablation is challenging. Blood flow in the coronary sinus (CS) may act as a heat sink and reduce the efficacy of radiofrequency ablation., Objective: This study investigates whether balloon occlusion of CS facilitates mitral isthmus ablation., Methods: This single-center, prospective, randomized controlled trial included patients undergoing ablation for atrial fibrillation. After circumferential pulmonary vein isolation and roof line ablation, mitral isthmus ablation was performed during left atrial appendage pacing using an irrigated ablation catheter (endocardium: maximum power: 40/50 W, maximum temperature: 48°C; CS: maximum power: 25/30 W, maximum temperature: 48°C). An air-filled 40 × 10-mm percutaneous transluminal angioplasty balloon (Opta Pro, Cordis Europa, LJ Roden, The Netherlands) was used to occlude the CS on the epicardial aspect of the ablation line. Left coronary and CS angiography were performed before and after the procedure., Results: Forty-six patients were studied. The balloon was successfully positioned in the distal CS in 20 of 23 patients (87%). Mitral isthmus block was achieved in 41 of 46 patients (91%). According to intention-to-treat analysis, there was significant reduction in the need for epicardial CS ablation (48% vs. 83%, P = .01) in the CS occlusion group but no difference in acute success rate. Secondary analysis showed reduction in mean total ablation time (9.4 ± 5.5 vs. 13.3 ± 4.6 minutes, P <.02) and mean CS ablation time (1.5 ± 2.8 vs. 3.4 ± 2.7 minutes, P <.05) in patients who had CS occlusion., Conclusion: Balloon occlusion of the CS during mitral isthmus ablation is feasible and safe. It significantly reduces ablation time and the need for CS ablation to achieve mitral isthmus block. The results support the hypothesis that heat sink is one of the obstacles to successful mitral isthmus ablation., (Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Aims: Mitral isthmus ablation is technically challenging, often requiring both endocardial and epicardial coronary sinus (CS) ablation. Blood flow in the CS and circumflex artery may act as a 'heat sink' and reduce the efficacy of radiofrequency ablation. This study investigates how the CS and circumflex artery diameters affect mitral isthmus ablation., Methods and Results: Thirty-five patients underwent ablation for atrial fibrillation. Irrigated-tip catheters were used during mitral isthmus ablation with the following settings: endocardial surface (maximum power: 40-50 W at the annular end of line; maximum temperature: 48°C); CS (maximum power: 25-30 W; maximum temperature: 48°C). The absence of block after 10 min of endocardial ablation led to CS ablation for up to 5 min. If there was still no block, further ablation was at the discretion of the physician. Coronary angiography and CS venography were performed and analysed with quantitative coronary angiography. Mitral isthmus block was achieved in 31 patients (89%). Twenty-three patients (74%) required CS ablation to achieve block. These patients were found to have significantly larger CS diameters (6.5 ± 1.2 vs. 5.4 ± 0.5 mm, P< 0.02). Coronary sinus diameter >59 mm predicted the need for CS ablation (specificity: 100%; sensitivity: 78%). Coronary sinus diameter correlated significantly with total mitral isthmus ablation time (r = 0.52, P < 0.003) and CS ablation time (r = 0.59, P < 0.0005), whereas circumflex diameter did not., Conclusion: Larger-diameter CS is associated with a need for CS ablation during mitral isthmus ablation. Coronary sinus but not circumflex diameter was significantly correlated with total and CS ablation time, supporting the hypothesis that the CS but not the circumflex artery acts as a heat sink.

Introduction: Mitral isthmus (MI) ablation for treatment of perimitral flutter is often performed during atrial fibrillation (AF) ablation but is technically challenging. Traditional assessment of MI conduction by left atrial activation mapping while pacing from either side of the line is time-consuming, and cannot be performed during ongoing ablation. Analysis of the coronary sinus (CS) activation pattern during left atrial appendage (LAA) pacing has been proposed as a simpler technique for evaluating MI conduction, enabling beat-to-beat assessment of conduction during ablation procedures and prompt identification of conduction block., Methods: MI conduction was evaluated in 40 patients undergoing MI ablation using both: ((i) endocardial activation mapping and other standard techniques, and (ii) CS activation pattern during LAA pacing (change from distal-to-proximal activation to proximal-to-distal taken to signify the onset of MI block)., Results: CS activation sequence was used to assess conduction in 39 of 40 patients (unable to advance CS catheter distally in one case). MI block was achieved in 36 of 39 cases. The mean MI conduction time (LAA to distal CS) was 92.9 +/- 25.9 ms prior to ablation and 178.4 +/- 59.9 ms after MI block was confirmed. The mean step-out in conduction time at point of block was 80.8 +/- 40.6 ms. In all individuals in whom CS activation indicated block, there was concordance with endocardial activation, differential pacing and, where detectable, presence of widely split double potentials. CS lesions were required to achieve block in 24 of 36 (67%) successful cases. Radiofrequency application time and procedure time to achieve MI block were 10.8 +/- 6.0 minutes and 21.1 +/- 15.3 minutes, respectively.

Background: One of the recognised complications of left atrial ablation for atrial fibrillation (AF) is stroke. Left atrial (LA) thrombus, which may be dislodged by catheter manipulation, is an absolute contraindication to ablation. It is unclear whether imaging of the left atrial appendage (LAA) by transesophageal echo (TEE) is mandatory to exclude LA clot prior to ablation, particularly in "low-risk" patients with paroxysmal AF and normal left ventricular (LV) function. Methods and Results: We carried out a retrospective analysis of pre-ablation TEE in patients presenting for ablation of AF. Images from 244 ablation procedures carried out in 148 patients were examined, including 106 patients with paroxysmal AF and normal LV function. Despite at least 4 weeks of pre-operative therapeutic anticoagulation with Warfarin (INR>2.0), LAA thrombus was identified in 4 patients (2.7% (0.1-5.3%)). These included 2 patients with paroxysmal AF and normal LV function, although both had a high arrhythmia burden. The thrombi regressed with intensification of anticoagulation. Conclusions: Pre-operative imaging of the LAA remains advisable to exclude thrombus prior to ablation for AF even in patients with paroxysmal AF and normal LV function, especially if there is a high AF burden.

Coronary flow reserve (CFR) is markedly reduced in patients with severe aortic valve stenosis (AS), but the exact mechanisms underlying this impairment of CFR in AS remain unclear. Reduced CFR is the key mechanism leading to myocardial ischemia symptoms and adverse outcomes in AS patients. The objective of this study was to develop an explicit mathematical model formulated with a limited number of parameters that describes the effect of AS on left coronary inflow patterns and CFR. We combined the mathematical V(3) (ventricular-valvular-vascular) model with a new lumped-parameter model of coronary inflow. One thousand Monte-Carlo computational simulations with AS graded from mild up to very severe were performed within a wide range of physiological conditions. There was a good agreement between the CFR values computed with this new model and those measured in 24 patients with isolated AS (r = 0.77, P < 10(-4)). A global sensitivity analysis showed that the valve effective orifice area (EOA) was the major physiological determinant of CFR (total sensitivity index = 0.87). CFR was markedly reduced when AS became severe, i.e., when EOA was <1.0 cm(2), and was generally exhausted when the EOA was <0.5-0.6 cm(2). The reduction of CFR that is associated with AS can be explained by the concomitance of 1) reduced myocardial supply as a result of decreased coronary perfusion pressure, and 2) increased myocardial metabolic demand as a result of increased left ventricular workload.

Background: Arrhythmia recurrence after atrial fibrillation (AF) ablation is often associated with pulmonary vein reconnection (PVR). We prospectively examined anatomical sites of both acute and chronic PVR., Methods: One hundred and fifty AF patients underwent PV wide encirclement and sites where immediate electrical isolation (EI) occurred were tagged using electroanatomic mapping/CT integration (Cartomerge, Biosense Webster, Diamond Bar, CA, USA). After 30 minutes PVs were checked and acute PVR sites marked at reisolation. Chronic PVR sites were marked at the time of repeat procedures., Results: On the left, immediate EI sites were predominantly on the intervenous ridge (IVR) and PV-left atrial appendage (PV-LAA) ridge. On the right they were at the roof, IVR, and floor of the PVs. Ninety-eight of one hundred and fifty patients had PVs checked after >30 minutes. Thirty-two of ninety-eight had acute PVR. This was mostly on the IVR and PV-LAA ridge on the left (88%), and on the roof and IVR on the right (78%). At repeat procedure, 38/39 patients had chronic PVR, predominantly on the IVR (61%) and PV-LAA ridge (21%) on the left, and on the roof, IVR, and floor of the right PVs (79%). There was minimal acute or chronic PVR posteriorly. Acutely PVR occurred close to the immediate EI site 60% of the time, but only 30% of the time chronically., Conclusion: Acute and chronic PVR sites have a preferential distribution. This may be determined by anatomical and technical factors. Knowledge of immediate EI sites may be beneficial acutely, but with chronic PVR a careful survey is required. These findings may help target ablation, improving safety and success.

Introduction: The complex anatomy of the left atrium (LA) makes location of ablation catheters difficult using fluoroscopy alone, and therefore 3D mapping systems are now routinely used. We describe the integration of a CT image into the EnSite NavX System with Fusion and its validation in patients undergoing atrial fibrillation (AF) or left atrial tachycardia (AT) catheter ablation., Methods and Results: Twenty-three patients (61 +/- 9.2 years, 16 male) with paroxysmal (14) and persistent (8) AF and persistent (1) AT underwent ablation using CT image integration into the EnSite NavX mapping system with the EnSite Fusion Dynamic Registration software module. In all cases, segmentation of the CT data was accomplished using the EnSite Verismo segmentation tool, although repeat segmentation attempts were required in seven cases. The CT was registered with the NavX-created geometry using an average of 24 user-defined fiducial pairs (range 9 to 48). The average distance from NavX-measured lesion positions to the CT surface was 3.2 +/- 0.9 mm (median 2.4 mm). A large, automated, retrospective test using registrations with random subsets of each patient's fiducial pairs showed this average distance decreasing as the number of fiducial pairs increased, although the improvement ceased to be significant beyond 15 pairs. In confirmation, those studies which had used 16 or more pairs had a smaller average lesion-to-surface distance (2.9 +/- 0.7 mm) than those using 15 or fewer (4.3 +/- 0.8 mm, P < 0.02). Finally, for the 13 patients who underwent left atrial circumferential ablation (LACA), there was no significant difference between the circumference computed using NavX-measured positions and CT surface positions for either the left pulmonary veins (178 +/- 64 vs. 177 +/- 60 mm; P = 0.81) or the right pulmonary veins (218 +/- 86 vs. 207 +/- 81 mm; P = 0.08)., Conclusion: CT image integration into the EnSite NavX Fusion system was successful in all patients undergoing catheter ablation. A learning curve exists for the Verismo segmentation tool; but once the 3D model was created, the registration process was easily accomplished, with a registration error that is comparable with registration errors using other mapping systems with CT image integration. All patients went on to have subsequent successful ablation procedures. Where LACA was performed (13 patients), only four patients required segmental ostial lesions to achieve electrical isolation.

Background: Catheter ablation (CA) by wide encirclement of pulmonary veins (WEPV) restores sinus rhythm in up to 95%. Complex PV-left atrial (LA) connections make achieving electrical isolation (EI) challenging. We examined anatomical and technical features associated with resistance to EI during WEPV in a prospective study., Methods: One hundred one consecutive patients with symptomatic AF underwent first-time CA guided by electroanatomic mapping and CT integration (Cartomerg). Following double-transseptal access, WEPV was performed. After completion of PV encirclement, the line was mapped and where no signal could be obtained, CA was performed inside the WE line at the site of earliest PV breakthrough on the circular mapping catheter. Sites of EI were tagged. Anatomic studies of corresponding regions of the venoatrial junction in 24 adult hearts were performed., Results: Sites resistant to EI were located at the inferior quadrant (P < 0.001) for the RSPV, superior quadrant (P < 0.001) for the RIPV, and the inferior and anterior quadrants (P < 0.001) for the LSPV. EI was significantly less frequent at the posterior quadrant (P < 0.001) for the LIPV. To achieve EI, CA was necessary inside the WE on the intervenous ridge on the right in 51% and on the left in 41%. The LPV/LAA ridge was investigated by anatomic studies that demonstrated considerable variation in the narrowest width (3-23.7 mm) and transmural thickness (1-5 mm)., Conclusion: Sites of EI after WEPV have a preferential distribution determined by anatomic features. CA on the intervenous ridge is required in a significant proportion of patients to achieve EI. Atrial folds and ridges increase myocardial thickness creating technical and anatomic challenges for achieving transmural lesions.

The treatment of ventricular tachycardia (VT) in patients with underlying ischaemic heart disease (IHD) remains a challenge. Ablation of these arrhythmias may have a significant impact on quality of life for patients. For those patients with haemodynamically unstable VT, ablation success rates have been improved by the use of non-contact mapping. Care has to be taken in the analysis and interpretation of non-contact mapping studies, as chamber size and filter settings have a large effect on the appearance of the activation maps produced. Despite this limitation the majority of VT exit sites and part of the diastolic pathway can be identified with non-contact mapping techniques.

We report on the case of an 18-year-old girl with asymptomatic incessant ventricular tachycardia. Initial attempts at endocardial ablation failed and she was monitored until her cardiac function deteriorated. A percutaneous epicardial approach with electroanatomical mapping was then used which successfully terminated the tachycardia. Left ventricular size and function subsequently returned to normal. This case demonstrates that percutaneous epicardial ablation of ventricular tachycardia is safe and feasible in young patients and highlights the importance of recognising this at an early stage.

Background: A detailed appreciation of left atrial/pulmonary vein (LA/PV) anatomy may be important in improving the safety and success of catheter ablation (CA) for atrial fibrillation (AF)., Objectives: The aim of this nonrandomized study was to determine the impact of computerized tomography (CT) image integration into a 3-dimensional (3D) mapping system on the clinical outcome of patients undergoing CA for AF., Methods: Ninety-four patients (age: 56 +/- 10 years) with AF (paroxysmal 46, persistent 48) underwent wide encirclement of ipsilateral PV pairs using irrigated radiofrequency ablation with the endpoint of electrical isolation. Ablation was guided by 3D mapping alone (electroanatomic 24, noncontact 23) in 47 (3DM group) patients and by CT image integration (Cartomerge) in 47 (CT group). In persistent AF, a combination of linear ablation and targeted ablation of complex fractionated electrograms was also performed., Results: Successful PV electrical isolation did not differ between the two groups. A significant reduction in fluoroscopy times was demonstrated in the CT group (49 +/- 27 minutes vs 3DM group 62 +/- 26 minutes, P = 0.03). Arrhythmia recurrence was reduced in the CT group (32% vs 51% in the 3DM group, P < 0.01). In 30 symptomatic patients (12 CT and 18 3DM), repeat procedures for AF (13 in 3DM and 5 CT, P < or = 0.10) and AT (5 in 3DM and 7 CT, P = NS) were performed. Overall success on 7-day monitor off antiarrhythmic drugs was achieved in 60% in the 3DM group when compared with 83% in the CT group (P < 0.05) at a follow-up of 25 +/- 5 weeks., Conclusion: CA for AF guided by CT integration was associated with reduced fluoroscopy times, arrhythmia recurrence, and increased restoration of sinus rhythm. Improved visualization of complex LA geometries might improve the safety and success of CA for AF.

Purpose: Respiratory motion has been identified as a source of artefacts in most medical imaging modalities. This paper reports on respiratory gating as a means to eliminate motion-related inaccuracies in PET imaging., Methods: Respiratory gating was implemented in list mode with physiological signal recorded every millisecond together with the PET data. Respiration was monitored with an inductive respiration monitor using an elasticised belt around the patient's chest. Simultaneous ECG gating can be maintained independently by encoding ECG trigger signal into the list-mode data. Respiratory gating is performed in an off-line workstation with gating parameters defined retrospectively. The technique was applied on a preliminary set of patient data with C(15)O., Results: Motion was visually observed in the cine displays of the sagittal and coronal views of the reconstructed respiratory gated images. Significant changes in the cranial-caudal position of the heart could be observed. The centroid of the cardiac blood pool showed an excursion of 4.5-16.5 mm (mean 8.5+/-4.8 mm) in the cranial-caudal direction, with more limited excursion of 1.1-7.0 mm (mean 2.5+/-2.2 mm) in the horizontal direction and 1.3-3.7 mm (mean 2.4+/-0.9 mm) in the vertical direction., Conclusion: These preliminary data show that the extent of motion involved in respiration is comparable to myocardial wall thickness, and respiratory gating may be considered in order to reduce this effect in the reconstructed images.

Background & Objectives: A disease surveillance model developed in the North Arcot district, Tamil Nadu, was found to be practical, efficient, inexpensive and useful for public health action to monitor the success of ongoing interventions and to detect and intercept outbreaks. It was centred in the private (voluntary) sector with full co-operation and participation by the government sector. As Kerala state wanted to replicate this model in all districts, one district was chosen to pilot test it centred within the existing district public health system, soliciting participation from the private sector. A two-year (1999-2001) performance of this model is presented., Methods: After elaborate preparations including the selection of 14 diseases to be reported and training of doctors in the private sector health care institutions and doctors and paramedical staff in all government health centres and hospitals, printed post cards were widely distributed. The business reply system was used so as to avoid handling postage stamps. Cards were received by the nodal officer in the district public health office and checked on a daily basis to detect disease prevalence and evidence of clustering in time and space. Swift action was taken on detecting case clustering. A monthly bulletin containing disease summaries and other useful information was freely distributed to all reporting centres., Results: On an average, just over 100 disease reports were received every month. The most frequently reported diseases were, in the descending order, leptospirosis, acute dysentery, typhoid fever and acute hepatitis. Among vaccine-preventable childhood diseases, only measles was reported, but no diphtheria, tetanus or whooping cough. Several outbreaks were detected early and interventions applied to intercept them. The most striking example was that of cholera, the occurrence of which was detected swiftly for instituting highly successful control measures., Interpretation & Conclusion: The district level disease surveillance system centred in the government public health system has been highly successful. Disease surveillance was responsible for the government to obtain information on the prevalence of leptospirosis in the district. The reports enabled the public health officers to detect disease-clustering as the early signals of outbreaks and to take quick remedial measures.

Background: QT interval prolongation occurs at rest and during exercise in pathological left ventricular hypertrophy. However, athletes with physiological hypertrophy have normal QT at rest. The aim of this study was to compare the effect of exercise on QT in athletes with echocardiographic left ventricular hypertrophy and normal controls, and explore differences in their response., Methods: Elite male rowers (n=15) with echocardiographic left ventricular hypertrophy, and normal volunteers (n=15) underwent 15 min of a Bruce protocol treadmill test. Electrocardiograms (ECGs) were recorded during each stage and every minute during recovery for 3 min. QT was measured at each stage. Corrected QT (QTc) was calculated using Bazett's formula., Results: QT at rest was significantly greater than QT after 3 min of recovery in the controls (0.36+/-0.02 vs. 0.32+/-0.04 s; P=0.001) but not in the athletes (0.36+/-0.03 vs. 0.34+/-0.02 s; P=0.05). Regression lines for QT versus heart rate showed a strongly negative correlation in both athletes and controls (y=0.463-0.0013x (r=0.91; P<0.0001) and y=0.461-0.0013x (r=0.93; P<0.0001), respectively), but greater individual homogeneity in the athletes., Conclusions: training-induced hypertrophy does not affect the heart rate/QT relationship. The more rapid recovery in QT and homogeneity of the heart rate/QT relationship in athletes compared to controls is likely to be a benign effect of myocardial fitness, but it is hypothesised that it may contribute to arrhythmias in the unfit individual after vigorous exertion.

Aim: To delineate the natural history of left ventricular remodelling following large anterior myocardial infarction (MI), in the era of aggressive medical therapy., Methods: Seventeen selected patients underwent cardiovascular magnetic resonance (CMR) at 2 weeks and 1, 3, 6 and 12 months post infarction., Results: There was a significant increase in left ventricular (LV) end-diastolic volume index (EDVI) and LV ESVI from 2 weeks to 1 month (P<0.05) but no significant change thereafter. The LV ejection fraction (EF) decreased from 2 weeks to 1 month (P<0.05) and then increased over the year (P=0.02). Throughout the study period the sphericity index increased. There was a significant and progressive decrease in LV mass index over the year, which was associated with a decrease in wall thickness at both the infarct and non-infarct sites. Independent predictors of an early increase in LVESVI were increasing age, increasing CK-MB and not receiving treatment with a statin., Conclusion: This study delineates the natural history of left ventricular remodelling in the modern medical era in those patients who have suffered a large anterior MI. Classical remodelling occurred up to 1 month, but thereafter was attenuated. These findings would suggest that remodelling is not as prevalent in the modern era, and that combined medical management with thrombolysis, ACEi, beta-blockers and statins may strongly influence the development of this remodelling.

Background: Development of left ventricular hypertrophy in aortic stenosis (AS) is accompanied by coronary microcirculatory dysfunction, demonstrated by an impaired coronary vasodilator reserve (CVR). However, evidence for regional abnormalities in myocardial blood flow (MBF) and the potential mechanisms is limited. The aims of this study were to quantitatively demonstrate differences in subendocardial and subepicardial microcirculation and to investigate the relative contribution of myocyte hypertrophy, hemodynamic load, severity of AS, and coronary perfusion to impairment in microcirculatory function., Methods and Results: Twenty patients with isolated moderate to severe AS were studied using echocardiography to assess severity of AS, cardiovascular magnetic resonance to measure left ventricular mass (LVM), and PET to quantify resting and hyperemic (dipyridamole 0.56 mg/kg) MBF and CVR in both the subendocardium and subepicardium. In the patients with most severe AS (n=15), the subendocardial to subepicardial MBF ratio decreased from 1.14+/-7 at rest to 0.92+/-7 during hyperemia (P<0.005), and subendocardial CVR (1.43+/-3) was lower than subepicardial CVR (1.78+/-35; P=0.01). Resting total LV blood flow was linearly related to LVM, whereas CVR was not. Increase of total LV blood flow during hyperemia (mean value, 89.6+/-6%; range, 17% to 233%) was linearly related to aortic valve area. The decrease in CVR was related to severity of AS, increase in hemodynamic load, and reduction in diastolic perfusion time, particularly in the subendocardium., Conclusions: CVR was more severely impaired in the subendocardium in patients with LVH attributable to severe AS. Severity of impairment was related to aortic valve area, hemodynamic load imposed, and diastolic perfusion rather than to LVM.

Background and Aim of the Study: The changes in geometry of the aortic root during the cardiac cycle are thought to be essential for optimal valve function, both in terms of leaflet stress and dynamic behavior. Using cardiac magnetic resonance (CMR), the study aim was to determine aortic root distensibility of the homograft (group H) and the Medtronic Freestyle xenograft (group F) after aortic root replacement, from a prospective randomized trial., Methods: CMR was performed in 15 patients (six homografts, nine Freestyle) at six months and one year after surgery. Percentage change in aortic radius (PCR) and pressure strain elastic modulus (PSEM) were measured as indices of distensibility, and results related to left ventricular mass (LVM)., Results: At six months after surgery, mean PCR was 12+/-2.5 in group H and 12.9+/-6.1 in group F (p = NS), and PSEM was 428.5+/-69.8 and 493.5+/-72.7 g/cm2, respectively (p = NS). PCR was reduced to 10+/-1.7% in group H, and by 8.5+/-2.8% in group F (p = NS), while PSEM was increased to 520.5+/-87.3 and 825+/-420.4, respectively (p = NS) at the one-year follow up. Regression analysis showed a correlation between PCR and LVM (r = 0.52, p = 0.08) and LVM index (r = 0.46, p = 0.14), respectively. In addition, there was a relationship between PSEM, LVM and LVM index, suggesting that the stiffer the root wall, the higher the postoperative LVM., Conclusion: Up to one year after aortic root replacement, the wall of both the allogenic and xenogenic valves retained near-normal distensibility. For the first time, a correlation was demonstrated between the elastic properties of the aortic root and LVM. The longer-term behavior and clinical implications of these findings require further investigation.

Background: Assessment of graft function after cardiac transplantation is essential for patient management and clinical research. Previous studies have found that the left ventricular (LV) ejection fraction (EF) by echocardiography (echo), radionuclide ventriculography (RNV), and cardiovascular magnetic resonance (CMR) is discrepant in patients with heart failure., Method: Twelve patients underwent LV EF assessment by echo, angiography (angio), RNV, and CMR one year following heart transplantation. The scans were analyzed independently in blinded fashion., Results: The mean EF was 63 +/- 6% by RNV, 66 +/- 6% by CMR, 70 +/- 12% by angio, and 74 +/- 4% by echo. Significant differences were found between CMR and echo (p < 0.001), RNV and echo (p < 0.001), and RNV and angio (p < 0.05). The correlation between the techniques was poor (r = 0.3-0.6), and the scatter plots also suggested considerable variations between techniques. This was confirmed by the wide Bland-Altman limits of agreement (ranging from 22 to 45%). These were particularly wide for comparisons with angiography (43-45%)., Conclusion: The EF measurement by echo, angio, RNV, and CMR are not interchangeable in patients following heart transplantation. The CMR and RNV provided the best agreement in EF and appear preferable for research studies. Echocardiography systematically overestimated LV EF and showed poor agreement with other techniques. Angiography overestimated LV function, and its routine use did not add to information gained from noninvasive studies.

Background and Aim of the Study: Regression of left ventricular hypertrophy (LVH) after aortic valve replacement has traditionally been measured by echocardiography. However, cardiovascular magnetic resonance (CMR) can be used to measure left ventricular function and mass more accurately and reproducibly. This translates into fewer patients being needed to demonstrate significant changes. The study aim was to demonstrate the feasibility of using CMR to measure left ventricular mass index (LVMI) and function in patients from a prospective randomized trial, and to compare homografts with the Medtronic Freestyle root replacement., Methods: Among 23 patients recruited, 17 had LVMI and function (end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and ejection fraction (EF)) measured pre- and postoperatively using CMR (eight homograft, nine Freestyle)., Results: Significant regression of LVH was seen in both groups one year postoperatively (homograft LVMI 145+/-44 g/m2 preoperative versus 83+/-23 g/m2 one year postoperatively; Freestyle LVMI 140+/-28 g/m2 versus 93+/-21 g/m2, respectively). At six months there was significant regression in the xenograft group (from 140+/-28 to 106+/-22 g/m2; p <0.05) and a trend towards regression in the homograft group (from 145+/-44 to 103+/-25 g/m2; p = NS). There was also a trend towards a reduction in EDV, ESV and SV, and an increase in EF over one year in both groups., Conclusion: Regression of LVH was measured using CMR in patients after aortic root replacement and coronary implantation with the homograft and Medtronic Freestyle root replacement. Despite the small number of patients studied, it was possible to demonstrate the extent and pattern of regression of left ventricular mass in the two groups.

Three types of 3-D TV system compatible with existing 2-D TV systems are proposed. These systems are not based on stereoscopic image techniques and do not impose any constraints on the viewer for 3-D perception. The first system makes use of the existing conventional color TV system for development of a 3-D TV system. The second system is based on the present monochromatic TV system. The third system depends on a light-emitting diode tank for 3-D display. To prove the validity of these systems a simulated experiment is demonstrated for the reproduction of a 3-D image using still photographs. All these systems are compared for their relative merits and demerits.