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Aims: To determine prognostic significance of global left ventricular (LV) contractile reserve, defined by dobutamine-induced changes of Tei index (ΔTei), in patients with dilated cardiomyopathy (DCM). [ABSTRACT FROM PUBLISHER]

BackgroundGestational hypertension (GH) is associated with hemodynamic changes, and alterations of systolic and diastolic left ventricular (LV) function. However, the magnitude and pattern of changes of different parameters of LV function and contractility in this patient population have not been fully clarified.MethodsThirty-five pregnant women with GH underwent three echocardiographic examinations, in second and third trimester of pregnancy, and 1 month after delivery. Twelve normotensive pregnant women served as gestational age-matched controls. Hemodynamic parameters and standard indexes of LV systolic and diastolic function were analyzed. Additionally, we have measured peak systolic velocity of mitral annulus (S′), end-systolic elastance (Ees), and early transmitral to early lengthening velocity of mitral annulus ratio (E/E′) as parameters of longitudinal function, contractility, and filling, respectively.ResultsWomen with GH had initially higher body weight, blood pressure, and heart rate (P < 0.005, P < 0.0001, and P = 0.011, respectively). Temporal analysis of different echocardiographic parameters revealed increase in wall thickness from baseline to second measurement, with consequential increase in LV mass in women with GH (P = 0.014 for septum, P = 0.010 for posterior wall, and P = 0.09 for LV mass). No significant changes of LV volumes, ejection fraction (EF), transmitral flow parameters, S′, Ees, and E/E′ were observed throughout the follow-up in both groups (P = nonsignificant for all). Importantly, pattern of changes was similar in both groups for all examined parameters (P = nonsignificant between groups, for all).ConclusionsIt appears that changes of LV longitudinal function, filling, and contractility during pregnancy are not significant and not influenced by GH.American Journal of Hypertension 2010; doi:10.1038/ajh.2009.168 [ABSTRACT FROM AUTHOR]

The article presents a study that investigates the impact of enhancing vagal tone acquired from chronic vagus nerve stimulation (VNS) on heart failure development in a canine high-rate ventricular pacing model in dogs. Study shows an improvement on heart rate variability and baroreflex sensitivity in the VNS dogs. Results are said to have indicated that chronic VNS can improve cardiac autonomic control and that VNS is associated with pronounced anti-inflammatory effects.

Two-dimensional (2-D) speckle tracking echocardiography (STE) accurately quantifies circumferential strain (Scirc) and radial strain (Srad) in humans and in large and small animals. This study was performed to assess sensitivity of Scirc and Srad to left ventricular (LV) dysfunction in mouse models. We performed 2-D and M-mode echocardiography 1) in 6 mice during superficial and profound isoflurane anesthesia, 2) serially in 12 mice to monitor the development of heart failure induced by transverse aortic constriction (TAC) and in 8 corresponding control mice, and 3) in 26 mice with varying degrees of TAC-induced heart failure and 12 corresponding control mice immediately before euthanasia. Fractional shortening (FS) and LV mass were measured from standard M-mode tracings, whereas Scirc and Srud were derived by STE. Percent fibrosis and myocyte diameters were assessed from whole heart cross-sectional specimens stained by Masson trichrome. Profound isoflurane anesthesia decreased Scirc (P = 0.027) but not Srad (P > 0.05). Mice subjected to TAC showed an immediate and sustained decrease in FS (P = 0.035), Scirc (P = 0.016), and Srad (P = 0.0 12). Scirc showed better correlation with FS (r = 0.56 and P < 0.0001) and LV mass (r = 0.42 and P = 0.0003) than Srad (r = 0.54 and P < 0.000 1 for FS and r = 0.37 and P = 0.0 14 for LV mass, respectively). Percent fibrosis correlated better with Scirc (r = 0.46 and P = 0.004) than with Srad (r = -0.32 and P = 0.05), whereas myocyte diameter showed similar correlation with both strains (r = 0.45 and r = -0.44, respectively, and P = 0.006 for both). STE correctly identifies LV dysfunction and histological changes in mice and can be used for the serial assessment of cardiac remodeling in murine models. [ABSTRACT FROM AUTHOR]

Objective: Occlusion of the left atrial appendage is proposed to reduce the risk of stroke in patients with atrial fibrillation. The third-generation atrial exclusion device, modified to provide uniform distribution of pressure at appendage exclusion, was assessed for safety and effectiveness in a canine model and compared with a surgical stapler. Methods: The atrial exclusion device consists of 2 parallel, straight, rigid titanium tubes and 2 nitinol springs with a knit-braided polyester fabric. Fourteen mongrel dogs were implanted with the device at the base of the left atrial appendage via a median sternotomy. In each dog, the right atrial appendage was stapled with a commercial apparatus for comparison. The animals were evaluated at 7 days (n = 3), 30 days (n = 5), and 90 days (n = 6) after implantation by epicardial echocardiography, left atrial and coronary angiography, gross pathology, and histology. Results: Left atrial appendage exclusion was complete and achieved without hemodynamic instability, and coronary angiography revealed that the left circumflex artery was patent in all cases. A new endothelial tissue layer developed on the occluded orifice of the left atrium 90 days after implantation. This endothelial layer was not evident on the stapled right atrial appendage. Conclusion: In dogs, the third-generation atrial exclusion device achieved easy, reliable, and safe exclusion of the left atrial appendage with favorable histologic results. Clinical application could provide a new therapeutic option for reducing the risk of stroke in patients with atrial fibrillation. [Copyright &y& Elsevier]

Purpose: Recent studies have demonstrated that ventricular rate control is a viable treatment strategy for patients in atrial fibrillation (AF). The purpose of this study was to determine whether or not the benefits of coupled pacing (ie, a proposed rate control therapy) could be used during persistent AF. Description: Six mongrel dogs were chronically implanted with endocardial atrial and ventricular pacemaker leads and two standard dual-chamber pacemakers. With the use of two custom “Y”-lead adapters, the pacemakers were used to induce AF and to apply coupled pacing. Left ventricular end-diastolic and systolic volumes were measured by echocardiography to determine ejection fractions. Evaluation: Persistent AF significantly increased both ventricular rate and left ventricular dimensions. After sustained coupled pacing had been applied for 3 to 4 weeks, left ventricular volumes and contractile rate were significantly reduced and returned toward the values measured prior to the induction of persistent AF. Coupled pacing increased the ejection fraction that had been reduced by persistent AF. Conclusions: Coupled pacing reversed the left ventricular remodeling caused by the tachycardia resulting from AF. [Copyright &y& Elsevier]

Objectives: We sought to investigate the short-term and midterm effects of left atrial appendage exclusion on left atrial function. Left atrial appendage exclusion is considered a possible therapeutic option for stroke prevention in patients with atrial fibrillation. Favorable outcomes have encouraged widespread use of left atrial appendage exclusion for cardiac surgical patients—even for patients in sinus rhythm who have stroke risk factors; however, the chronic effects on left atrial function of left atrial appendage exclusion are unclear. Methods: Nineteen mongrel dogs (29.7 ± 5.2 kg) in sinus rhythm were studied. The Doppler signals from the pulmonary venous flow, transmitral flow, and tissue Doppler imaging of mitral annular motion were obtained before and after left atrial appendage exclusion. Dogs were evaluated in the same manner at 7 days (n = 2), 30 days (n = 7), or 90 days (n = 10) after left atrial appendage exclusion. Results: Except for a significant increase in early diastolic transmitral flow velocity after left atrial appendage exclusion (P = .01), no significant differences were found in any parameters related to the transmitral flow and tissue Doppler imaging measurements throughout follow-up. The systolic components of pulmonary venous flow at follow-up revealed a significant reduction relative to baseline (peak systolic velocity P < .0001, systolic velocity-time integral P < .0001), despite the lack of significant changes in left atrial pressure, left ventricular volume, and stroke volume. Conclusion: Left atrial appendage exclusion may affect left atrial reservoir function in the short-term and midterm periods. Further long-term studies with more clinically relevant models are needed. [Copyright &y& Elsevier]

Our understanding of the physical underpinnings of the assessment of cardiac function is becoming increasingly sophisticated. Recent developments in cardiac ultrasound permit exploitation of many of these newer physical concepts with current echocardiographic machines. This review will first focus on the current approach to the assessment of cardiovascular hemodynamics by cardiac ultrasound. The next focus will be the assessment of global cardiac mechanics in systole and diastole. Finally, relationships between the cardiac structure and regional myocardial function, and the way regional function can be quantified by ultrasound, will be presented. This review also discusses the clinical impact of echocardiography and its future directions and developments. [Copyright &y& Elsevier]

Background: The left atrial appendage is a frequent source of thromboemboli in patients with atrial fibrillation. Exclusion of the left atrial appendage may reduce the risk of stroke in patients with atrial fibrillation. The atrial exclusion device, previously developed to perform left atrial appendage exclusion on a beating heart, was modified to accommodate different anatomic patterns of the human left atrial appendage and to ensure uniform pressure and occlusion. The purpose of this study was to evaluate this second-generation atrial exclusion device during a midterm period in a canine model. Methods: Ten mongrel dogs (mean weight 28.9 ± 4.6 kg) were used in this study. The atrial exclusion device, constructed from two parallel and rigid titanium tubes and two nitinol springs with a knit-braided polyester fabric, was implanted at the base of the left atrial appendage through a left thoracotomy on a beating heart using a specially designed delivery tool. Dogs were evaluated at 30 days (n = 4) and 90 days (n = 6) by epicardial echocardiography, left atrial and coronary angiography, gross pathology, and histologic inspection. Results: Device implantation was performed without complications in all dogs. Complete left atrial appendage exclusion without device migration or hemodynamic instability was confirmed, and there was no damage to the left circumflex artery or pulmonary artery. Macroscopic and microscopic assessments revealed favorable biocompatibility during midterm follow-up. Conclusion: The atrial exclusion device enabled rapid, reliable, and safe exclusion of the left atrial appendage. Clinical application may provide a new therapeutic option for reducing the risk of stroke in patients with atrial fibrillation. [Copyright &y& Elsevier]

Objective: The left atrial appendage is a frequent source of thromboemboli in patients with atrial fibrillation. Exclusion or excision of the left atrial appendage may reduce the risk of stroke in patients with atrial fibrillation. We evaluated the ability of a novel device to exclude the left atrial appendage during early and intermediate follow-up periods in a canine model. Methods: Eight mongrel dogs (mean weight 29.1 ± 4.0 kg) were used in this study. The occlusion device, constructed from 2 stainless steel strips covered with a knit braided polyester fabric, was implanted at the base of the left atrial appendage through a left thoracotomy on a beating heart. Dogs were evaluated at 7 days (n = 2), 30 days (n = 2), and 90 days (n = 4) by epicardial echocardiography, left atrial angiography, histologic inspection, and gross pathology. Results: Device implantation was performed without complications in all animals. Complete exclusion of the left atrial appendage from the circulation was confirmed acutely and chronically by echocardiographic and angiographic evaluations. There was no device migration or damage to adjacent structures. Conclusion: This novel device enables rapid, reliable, and safe exclusion of the left atrial appendage. The device provides a new therapeutic option for reducing the risk of stroke in patients with atrial fibrillation. [Copyright &y& Elsevier]

While the heart size maintains a constant proportion to body size, heart function parameters, such as heart rate and cardiac output, show a more complex scaling pattern. How these phenomena affect the long-axis left ventricular (LV) function is unknown. We studied 10 mice, 15 rats, 6 rabbits, 8 mongrel dogs and 38 human volunteers. Doppler tissue echocardiography data were postprocessed to reconstruct mitral annulus (MA) peak systolic velocity and displacement. The relationship between MA peak velocity, MA displacement and LV ejection time, and LV end-diastolic volume (and mass) were fit to an allometric (power-law) equation . LV mass varied from 0.062 to 255 g, while end-diastolic volume varied from 0.014 to 205 ml. β values of the relation between LV ejection time and LV end-diastolic volume and mass were 0.247 ± 0.017 and 0.267 ± 0.018, respectively. β values of the relationship between MA displacement and LV end-diastolic volume and mass were 0.358 ± 0.047 and 0.390 ± 0.051 ( P < 0.023 versusβ of LV ejection time). β values of the relationship between MA peak systolic velocity and LV end-diastolic volume and mass were 0.096 ± 0.012 and 0.100 ± 0.013, respectively ( P < 0.0001 versus 0). Finally, β values of the relationship between the long-to-short axis displacement ratio and LV end-diastolic volume and mass were 0.077 ± 0.017 and 0.086 ± 0.019 ( P < 0.0001 versus 0). We conclude that MA velocity, displacement, and long-to-short axis displacement ratio scale allometrically to heart size. This reduces the relative long-axis contribution to heart function in small mammals. [ABSTRACT FROM AUTHOR]

Aims: To validate the accuracy of mitral annular motion assessed by real-time three-dimensional echocardiography (RT3DE) as a surrogate for determination of the left ventricular function in comparison with magnetic resonance imaging (MRI).Methods and results: Forty-seven patients with a variety of cardiac pathologies underwent both RT3DE and MRI exams. After 3D data sets were transferred to a PC with a custom-made program, nine consecutive rotational apical plane images (20° apart) were displayed. The two mitral leaflet insertion points were manually identified in each plane. The geometry of the mitral annulus was reconstructed from a total of 18 coordinates (x, y, z), and the changes in mitral annular area and mitral annular motion along the apical long axis were calculated. The left ventricular ejection fraction (LVEF) determined by MRI was 41±18%, and 24 patients had LVEF<50%. Mitral annular motion (y) obtained by RT3DE was 11 ± 5 mm and correlated moderately well with LVEF (x) measured by MRI (r = 0.84, y = 0.25x+0.43, p<0.0001). The mitral annular motion < 12 mm was a good threshold for detecting LVEF<50% with 96% sensitivity, 85% specificity, and 91% accuracy.Conclusion: Mitral annular motion determined by RT3DE correlated moderately well with LVEF; and systolic motion, <12 mm, accurately detected LV dysfunction. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess whether Frank-Starling mechanism has an independent effect on left ventricular (LV) performance in atrial fibrillation (AF).Ventricular performance in AF depends on variable contractility through the interval-force mechanism based on the ratio of preceding and pre-preceding RR intervals (RRp/RRpp). The impact of end-diastolic volume (EDV) variability, through the Frank-Starling mechanism, is not well understood.We induced AF in 16 open chest dogs. RR intervals, LV pressure, LV volume, and aortic flow were collected for >400 beats during rapid AF (ventricular cycle length 292 ± 66 ms). In six of the dogs, additional data were collected while average ventricular cycle length was prolonged from 258 ± 34 ms to 445 ± 80 ms by selective vagal nerve stimulation of the AV node.The relations of maximal LV power (LVPower) and peak LV pressure derivative (dP/dt) versus RRp/RRpp were fitted to the equation y = A * (1 − EXP (RRp/RRppmin − RRp/RRpp)/C) and the residuals (RES) of these relations were analyzed. LVPower and dP/dt strongly correlated with RRp/RRpp (r2 = 0.67 ± 0.12 and 0.66 ± 0.12, P < .0001 for all correlations). Importantly, RES-LVPower and RES-dP/dt showed linear correlation with EDV (r2 = 0.20 ± 0.14 and r2 = 0.24 ± 0.17, P < .01 for all correlations). In the six dogs with slowed average ventricular rate, the slope of both residual relationships (RES-LVPower vs EDV and RES- dP/dt vs EDV) decreased (P < .03 for both).The Frank-Starling mechanism contributes to ventricular performance in AF independently of the interval-force effects of the beat-to-beat variability in cardiac contractility. The Frank-Starling mechanism is sensitive to the average ventricular rate. [Copyright &y& Elsevier]

Objective: The objective of this study was to evaluate the changes in mitral annular and left ventricular dimensions and left ventricular pressure–volume relations produced by the Myocor Coapsys device that has been developed to treat functional mitral regurgitation (MR) off-pump. Methods: The Coapsys device, which consists of anterior and posterior epicardial pads connected by a sub-valvular chord, was implanted in seven dogs with functional MR resulting from pacing induced cardiomyopathy. The Coapsys device was then sized by drawing the posterior leaflet and annulus toward the anterior leaflet. During sizing, MR grade was assessed using color flow Doppler echocardiography. Final device size was selected when MR was eliminated or minimized. Following implantation, heart failure was maintained by continued pacing for a period of 8 weeks. Mitral annular and left ventricular dimensions and left ventricular pressure–volume relations were evaluated by two-dimensional echocardiography and a conductance catheter, respectively, at pre-sizing, post-sizing, and after 8 weeks. Results: All implants were performed on beating hearts without cardiopulmonary bypass. Mean MR grade was reduced from 2.9±0.7 at pre-sizing to 0.7±0.8 at post-sizing (P<0.001), and was maintained at 0.8±0.8 after 8 weeks (P<0.01). The septal–lateral dimensions were significantly reduced at both mitral annular level [2.4±0.2 cm at pre-sizing, 1.5±0.3 cm at post-sizing (P<0.001), and 1.8±0.3 cm after 8 weeks (P<0.05)] and mid-papillary level [4.1±0.4 cm at pre-sizing, 2.4±0.2 cm at post-sizing (P<0.001), and 3.3±0.4 cm after 8 weeks (P<0.001)]. The end-systolic pressure–volume relation shifted leftward at post-sizing with a significantly steeper slope (P=0.03). There was a significant (P=0.03) leftward shift of the end-diastolic pressure–volume relation at post-sizing. After 8 weeks, these changes in pressure–volume relations tended to return to pre-sizing relations. Conclusions: The Coapsys device significantly reduced MR by treating both the mitral annular dilatation and the papillary muscle displacement. Despite these significant dimensional changes, the Coapsys device did not negatively affect the left ventricular pressure–volume relations. [Copyright &y& Elsevier]

Introduction: Although invasive studies have shown that cardiac resynchronization therapy by biventricular pacing improves left ventricular (LV) function in selected heart failure patients, it is impractical to apply such techniques in the clinical setting. The aim of this study was to assess the acute effects of cardiac resynchronization therapy by noninvasive techniques. Methods and Results: Twenty-two patients enrolled in the InSync trial (age 64 ± 9 years, 18 men and 4 women; all with ejection fraction <35% and QRS >130 msec) were studied 1 to 12 months after pacemaker implantation during pacing, and while ventricular pacing was inhibited. Regional myocardial strains of the interventricular septum, LV free wall, and right ventricular free wall were derived from color Doppler tissue echocardiography. Peak power index was calculated as a product of simultaneously recorded noninvasive blood pressure and pulse-wave (PW) Doppler velocity of the LV outflow tract. The Z ratio (sum of LV ejection and filling times divided by RR interval) and tei index were calculated from PW Doppler data. During pacing, overall regional strain improved (P = 0.01), while the LV strain coefficient of variation decreased from 2.7 ± 2.4 to 1.3 ± 0.7 (P = 0.009). Additionally, peak power index improved from 84 ± 24 to 94 ± 27 cm · mmHg/sec (P = 0.004). The Z ratio increased from 0.71 ± 0.08 to 0.78 ± 0.07 (P = 0.0005), while the tei index decreased from 0.86 ± 0.33 to 0.59 ± 0.16 (P = 0.0002). Conclusion: Using novel noninvasive indices, we demonstrated that cardiac resynchronization therapy improves LV performance. [ABSTRACT FROM AUTHOR]

Transthoracic echocardiography (TTE) grading of aortic stenosis (AS) is challenging when parameters are discrepant, and four-dimensional cardiac computed tomography (4D-CCT) is increasingly utilized for transcatheter intervention workup. We compared TTE and 4D-CCT measures contributing to AS quantification. AS patients (n = 80, age 86 ± 10 years, 71% men) referred for transcatheter replacement in 2014–2017 were retrospectively studied, 20 each with high-gradient AS (HG-AS), classical and paradoxical low-flow low-gradient AS (CLFLG-AS and PLFLG-AS), and normal-flow low-gradient AS (NFLG-AS). Correlation and Bland–Altman analyses were performed between TTE and 4D-CCT parameters. There were moderate-to-high TTE versus 4D-CCT correlations for left ventricular volumes, function, mass, and outflow tract dimensions (r = 0.51–0.88), though values were mostly significantly higher by 4D-CCT (p < 0.001). Compared with 4D-CCT planimetry of aortic valve area (AVA), TTE estimates had modest correlation (r = 0.37–0.43) but were significantly lower (by 0.15–0.32 cm2). The 4D-CCT estimate of LVSVi lead to significant reclassification of AS subtype defined by TTE. In conclusion, 4D-CCT quantified values were higher than TTE for the left ventricle and AVA, and the AS subtype was reclassified based on LVSVi by 4D-CCT, warranting further research to establish its clinical implications and optimal thresholds in severe AS management. [ABSTRACT FROM AUTHOR]