Amit Bhan

Left ventricular hypertrophy in athletes

Participation in regular intensive exercise is associated with a modest increase in left ventricular wall thickness (LVWT) and cavity size. The magnitude of these physiological changes is predominantly determined by a variety of demographic factors which include age, gender, size, ethnicity, and sporting discipline. A small minority of male athletes participating in sporting disciplines involving intensive isotonic and isometric exercise may exhibit substantial increases in cardiac size that overlap with the phenotypic manifestation of the cardiomyopathies. The most challenging clinical dilemma incorporates the differentiation between physiological left ventricular hypertrophy (LVH) (athletes heart) and hypertrophic cardiomyopathy (HCM), which is recognized as the commonest cause of non-traumatic exercise related sudden cardiac death in young (<35 years old) athletes. This review aims to highlight the distribution and physiological upper limits of LVWT in athletes, determinants of LVH in athletes, and echocardiographic methods of differentiating athletes heart from HCM.

Real-Time Three-Dimensional Transesophageal Echocardiography Adds Value to Transcatheter Aortic Valve Implantation

BACKGROUND Successful transcatheter aortic valve implantation (TAVI) mandates comprehensive, accurate multimodality imaging. Echocardiography is involved at all key stages and, with the advent of real-time three-dimensional (3D) transesophageal echocardiography, is uniquely placed to enable periprocedural monitoring. The investigators describe a comprehensive two-dimensional (2D) and 3D echocardiographic protocol, and the additional benefits of 3D TEE, within a high-volume TAVI program. METHODS TAVI was performed with 2D and 3D transesophageal echocardiographic and fluoroscopic guidance in consecutive high-risk patients with symptomatic severe aortic stenosis. The role of TEE, including the additive value of 3D TEE, was examined, and procedural and echocardiographic outcomes were evaluated. A 3D sizing transcatheter heart valve (THV) strategy was used, except as mandated by study protocol. RESULTS Procedural success was achieved in 99% of 256 patients (mean age, 82.9 ± 7.1 years, mean logistic European System for Cardiac Operative Risk Evaluation score, 21.6 ± 11.2%; mean aortic valve area, 0.63 ± 0.19 cm(2)), with no procedural deaths. Acceptable 2D and 3D transesophageal echocardiographic images were achieved in all patients. Aortic valve annular dimensions by 2D transthoracic echocardiography, 2D TEE, and 3D TEE were 21.6 ± 1.9 mm, 22.5 ± 2.2 mm (P < .001), and 23.0 ± 2.0 mm (P = .004 vs 2D TEE), respectively. The 2D THV sizing strategy would have changed THV selection in 23% of patients, downsizing in most. Three-dimensional TEE provided superior spatial visualization and anatomic orientation and optimized procedural performance. Postprocedural mild, moderate, and severe paravalvular aortic regurgitation was observed in 24%, 3%, and 0% of patients, respectively, with no or trace transvalvular aortic regurgitation in 95%. A second valve was successfully deployed in five patients, and TEE detected five other periprocedural complications. CONCLUSIONS A systematic, comprehensive echocardiographic protocol, incorporating the additional benefits of 3D TEE, has a vital role within a TAVI program and, combined with a 3D THV sizing strategy, contributes to excellent outcomes.

Real-time 3D echo in patient selection for cardiac resynchronization therapy.

OBJECTIVES this study investigated the use of 3-dimensional (3D) echo in quantifying left ventricular mechanical dyssynchrony (LVMD), its interhospital agreement, and potential impact on patient selection. BACKGROUND assessment of LVMD has been proposed as an improvement on conventional criteria in selecting patients for cardiac resynchronization therapy (CRT). Three-dimensional echo offers a reproducible assessment of left ventricular (LV) structure, function, and LVMD and may be useful in selecting patients for this intervention. METHODS we studied 187 patients at 2 institutions. Three-dimensional data from baseline and longest follow-up were quantified for volume, left ventricular ejection fraction (LVEF), and systolic dyssynchrony index (SDI). New York Heart Association (NYHA) functional class was assessed independently. Several outcomes from CRT were considered: 1) reduction in NYHA functional class; 2) 20% relative increase in LVEF; and 3) 15% reduction in LV end-systolic volume. Sixty-two cases were shared between institutions to analyze interhospital agreement. RESULTS there was excellent interhospital agreement for 3D-derived LV end-diastolic and end- systolic volumes, EF, and SDI (variability: 2.9%, 1%, 7.1%, and 7.6%, respectively). Reduction in NYHA functional class was found in 78.9% of patients. Relative improvement in LVEF of 20% was found in 68% of patients, but significant reduction in LV end-systolic volume was found in only 41.5%. The QRS duration was not predictive of any of the measures of outcome (area under the curve [AUC]: 0.52, 0.58, and 0.57 for NYHA functional class, LVEF, and LV end-systolic volume), whereas SDI was highly predictive of improvement in these parameters (AUC: 0.79, 0.86, and 0.66, respectively). For patients not fulfilling traditional selection criteria (atrial fibrillation, QRS duration <120 ms, or undergoing device upgrade), SDI had similar predictive value. A cutoff of 10.4% for SDI was found to have the highest accuracy for predicting improvement following CRT. CONCLUSIONS the LVMD quantification by 3D echo is reproducible between centers. SDI was an excellent predictor of response to CRT in this selected patient cohort and may be valuable in identifying a target population for CRT irrespective of QRS morphology and duration.

High-frequency speckle tracking echocardiography in the assessment of left ventricular function and remodeling after murine myocardial infarction.

The objectives of this study were to assess the feasibility and accuracy of high-frequency speckle tracking echocardiography (STE) in a murine model of myocardial infarction (MI). STE is used clinically to quantify global and regional cardiac function, but its application in mice is challenging because of the small cardiac size and rapid heart rates. A high-frequency micro-ultrasound system with STE (Visualsonics Vevo 2100) was compared against magnetic resonance imaging (MRI) for the assessment of global left ventricular (LV) size and function after murine MI. Animals subjected to coronary ligation (n = 46) or sham ligation (n = 27) were studied 4 wk postoperatively. Regional and global deformation were also assessed. STE-derived LV ejection fraction (EF) and mass correlated well with MRI indexes (r = 0.93, 0.77, respectively; P < 0.001), as did STE-derived mass with postmortem values (r = 0.80, P < 0.001). Higher STE-derived volumes correlated positively with MRI-derived infarct size (P < 0.01). Global strain parameters were significantly reduced after MI (all P < 0.001) and strongly correlated with LV mass and MRI-derived infarct size as promising surrogates for the extent of remodeling and infarction, respectively (both P < 0.05). Regional strain analyses showed that radial strain and strain rate were relatively preserved in anterior basal segments after MI compared with more apical segments (P < 0.001); however, longitudinal strain and strain rate were significantly impaired both basally and distally (P < 0.001). Strain-derived parameters of dyssynchrony were significantly increased in the MI group (P < 0.01). Analysis time for STE was 210 ± 45 s with acceptable inter- and intraobserver variability. In conclusion, high-frequency STE enables quantitative assessment of regional and global function in the remodeling murine LV after MI.

Optimization of cardiac resynchronization therapy.

Cardiac resynchronization is now an accepted and widespread therapy for patients with left ventricular (LV) systolic dysfunction. However, there are still a significant number of patients that do not appear to gain benefit, and this is currently the focus of a great deal of research. Contemporary resynchronization devices allow manipulation of both atrioventricular (AV) and ventricular‐to‐ventricular (VV) delays and there is evidence that optimization of these delays has a positive effect on hemodynamics. However, there are many ways that optimization can be performed and there is little consensus on how, if at all, it should be incorporated into clinical practice.

Three-Dimensional Echocardiography

Over the past two to three decades echocardiography has come a considerable distance from the early M-mode machines, and has become an indispensable diagnostic tool in any cardiovascular department. It has long been proved to be safe and cost-effective, and its clinical versatility has steadily increased with the continued integration of newer techniques, such as two-dimensional and harmonic imaging, Doppler and much more. One of the more recent developments in the field is three-dimensional echocardiography (3DE). 3DE, in various forms, has been used as a research tool for many years now, but lately improvements in software and transducer technology have begun to facilitate its integration into clinical practice. As with any technique, 3DE has its strengths and weaknesses, and these must be fully appreciated if it is to be utilised effectively.

Real-time three-dimensional myocardial contrast echocardiography: is it clinically feasible?

AIMS Real-time 3D echocardiography (RT3DE) and 2D low mechanical index (LMI), contrast specific, myocardial perfusion imaging are now both accepted techniques. We evaluated the feasibility of an RT3DE LMI implementation in unselected patients. METHODS AND RESULTS Forty-six patients undergoing contrast enhanced dobutamine stress echo were imaged with novel 3D LMI power modulation software. All patients underwent contrast enhanced 2D and RT3DE acquisitions, in left ventricular opacification (LVO), and LMI perfusion modes. The data sets were evaluated segmentally for wall motion (WM) and myocardial contrast enhancement. Of the 736 evaluated segments, WM could be assessed in 726 (98.6%) of the 2D and 708 (96.2%) 3D segments (P = 0.007). Perfusion could be assessed in 721 (98%) of 2D and 701 (95.2%) of 3D segments (P = 0.006). Six hundred and sixty-one segments had normal WM and thickening in 2D and of these RT3DE demonstrated normal myocardial opacification in 77.2% of basal, 85% of mid, and 91.8% of apical segments. Thirty-four segments were akinetic, with no evidence of perfusion in 2D, and of these RT3DE revealed a perfusion defect in 31 (91%, P = NS). CONCLUSION LMI RT3DE evaluation of myocardial perfusion is feasible in most segments. It has the potential to accurately locate and possibly quantify perfusion defects.

Myocardial abscess: a rare complication of valvular endocarditis demonstrated by 3D contrast echocardiography.

Myocardial abscess is a rare and often fatal complication of valvular endocarditis. We present a case of a patient with aortic valve endocarditis whose post-operative course was complicated by a large left ventricular abscess. The spatial location of the defect was difficult to assess with 2D transthoracic echocardiography (TTE); however, real-time 3D contrast TTE allowed us to visualize the full extent of the defect and its precise anatomical location, prior to successful surgical resection.

Echo Determinants of Dyssynchrony (Atrioventricular and Inter- and Intraventricular) and Predictors of Response to Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) has revolutionized not only the treatment of chronic heart failure but also how we assess left ventricular (LV) dysfunction on echo. Increasingly, it has become clear that identifying and quantifying delays in events during the cardiac cycle is an important assessment in LV dysfunction as it has prognostic implications for patients undergoing CRT. The delays in atrioventricular, right‐to‐left ventricular, and LV segmental contraction have been shown to be important components in cardiac performance, and this review provides an overview of the commonest methods used for these assessments and their implications for selecting patients for biventricular pacing.

Pulmonary Haemodynamics in Sickle Cell Disease Are Driven Predominantly by a High-Output State Rather Than Elevated Pulmonary Vascular Resistance: A Prospective 3-Dimensional Echocardiography/Doppler Study.

Aims Patients with sickle cell disease have significant morbidity and mortality. Pulmonary hypertension is suggested to be an important contributor but its nature and severity in these patients and how best to non-invasively assess it are controversial. We hypothesised that a high-output state rather than primary pulmonary vascular pathology may be the major abnormality in sickle cell disease. This study aimed to evaluate the characteristics and severity of pulmonary hypertension in patients with sickle cell disease using detailed echocardiography. Methods and Results We undertook a prospective study in 122 consecutive stable outpatients with sickle cell disease and 30 age, gender and ethnicity-matched healthy controls. Echocardiographic evaluation included 3D ventricular volumes, sphericity, tissue Doppler, and non-invasive estimation of pulmonary vascular resistance. 36% of patients had a tricuspid regurgitant velocity ≥2.5 m.s-1 but only 2% had elevated pulmonary vascular resistance and the prevalence of right ventricular dysfunction was very low. Patients with raised tricuspid regurgitant velocity had significantly elevated biventricular volumes and globular left ventricular remodelling, related primarily to anaemia. In a subgroup of patients who underwent cardiac catheterization, invasive pulmonary haemodynamics confirmed the echocardiographic findings. Conclusions Elevated cardiac output and left ventricular volume overload secondary to chronic anaemia may be the dominant factor responsible for abnormal cardiopulmonary haemodynamics in patients with sickle cell disease. 3D echocardiography with non-invasive estimation of pulmonary vascular resistance represents a valuable approach for initial evaluation of cardiopulmonary haemodynamics in sickle cell disease.