Left anterior descending coronary artery flow impaired by right ventricular apical pacing: The role of systolic dyssynchrony

Introduction

Right ventricular (RV) pacing may affect myocardial perfusion and coronary blood flow; however, it remains unknown whether this is related to systolic dyssynchrony induced by RV pacing. This prospective study was aimed to assess the relationship between dyssynchrony and the changes of coronary blood flow.

Methods

Seventy patients with sinus node dysfunction were prospectively enrolled. Coronary flow was evaluated by measuring diastolic velocity time integral (VTI) and duration at the distal-portion of left anterior descending coronary artery (LAD) with transthoracic echocardiography at baseline and follow-up. Systolic dyssynchrony was assessed with tissue Doppler imaging by time standard deviation to peak systolic velocity of 12 left ventricular segments (Ts-SD, cutoff value ≥ 33 ms).

Results

Adequate data for analysis was available from 65 patients. At follow-up (mean follow up time: 127 ± 45 days), LAD velocity-time integral (LAD-VTI: 12.1 ± 4.2 vs. 10.7 ± 4.6 cm, p < 0.001) was decreased and there was deterioration of left ventricular systolic function (left ventricular ejection fraction: 65 ± 7% vs. 62 ± 7%). However, these changes were only detected in those with RV pacing induced systolic dyssynchrony. Significant reduction of LAD-VTI (defined as ≥ 5%) occurred in 34 (52%) patients which was more prevalent in those with pacing-induced systolic dyssynchrony than those without (85.3% versus 16.1%, χ² = 31.1, p < 0.001). Though similar at baseline, LAD-VTI was significantly lower in the dyssynchrony group at follow up (p < 0.001). Cox-regression analysis showed that pacing-inducing systolic dyssynchrony [hazard ratio (HR): 3.62, p = 0.009] and higher accumulative pacing percentage (HR: 1.02, p = 0.002) were independently associated with reduction of LAD-VTI. ROC curve demonstrated that accumulative pacing percentage ≥ 35% was 97% sensitive and 84% specific in revealing significant reduction (area under the curve: 0.961, p < 0.001).

Conclusions

RV pacing induced dyssynchrony is associated with reduced coronary flow and this may account for, in part, the deleterious effect of RV pacing on ventricular function over time.     

Evolving changes in Doppler mitral flow velocity pattern in rats with hypertensive hypertrophy

OBJECTIVES

The aim of our study was to explore evolving changes in a mitral flow velocity pattern (MFVP) and its hemodynamic and pathological correlates in hypertensive rats in an isolated diastolic heart failure model.

BACKGROUND

Development of left ventricular (LV) hypertrophy and concomitant diastolic dysfunction cause heart failure in hypertensive hearts even with normal systolic function; however, associated evolving change in MFVP is still unclear.

METHODS

Mitral flow velocity pattern was recorded every 2 weeks from 7 to 19 weeks in six hypertensive rats. Hemodynamic and pathological correlates of Doppler mitral flow indexes were examined as an additional part of the study using the hypertensive rats at the age of 13 weeks (compensatory stage, N = 7) and at 19 weeks (heart failure stage, N = 8).

RESULTS

Initial development of pressure overload LV hypertrophy resulted in a decrease in early diastolic filling wave (E), a reciprocal increase in the filling wave due to atrial contraction (A) and prolongation of deceleration time of E wave (relaxation abnormality pattern). These changes were associated with an increase in tau, an index of LV relaxation, but without a change in LV end-diastolic pressure. Transition to congestive heart failure caused an increase in E, a decrease in A and shortening of deceleration time. These changes were not associated with further increase in tau but with elevation of LV end-diastolic pressure, reflecting marked LV hypertrophy and myocardial fibrosis.

CONCLUSIONS

Development of pressure overload LV hypertrophy is associated with evolving changes in MFVP from normal to relaxation abnormality pattern and, in turn, to pseudonormalized to restrictive pattern. Analysis of MFVP may be useful to follow not only functional but also constitutional changes of the myocardium in hypertensive hearts.     

Determination of Left Ventricular Filling Pressure by Doppler Echocardiography in Patients With Coronary Artery Disease: Critical Role of Left Ventricular Systolic Function

Objectives. This study was designed to determine the usefulness of transthoracic Doppler measurements in detecting increased left ventricular (LV) end-diastolic pressure in patients with coronary artery disease, specifically examining the influence of systolic function on the accuracy of these methods.

Background. Studies that have correlated Doppler indexes with LV filling pressures primarily involved patients with LV systolic dysfunction. The reliability of Doppler indexes in estimating filling pressures in patients with coronary artery disease and preserved systolic function is unclear.

Methods. Pulsed wave Doppler transmitral and pulmonary venous flow velocity curves and LV pressure were recorded in 83 patients with coronary artery disease.

Results. Conventional Doppler indexes (deceleration time of mitral E wave velocity, ratio of peak mitral E to A wave velocities and pulmonary venous systolic fraction) correlated with LV filling pressure in patients with an ejection fraction (EF) ≤50% but not in those with an EF >50%. Previously published regression analysis for prediction of LV filling pressure was accurate in patients with an EF ≤50% but not in those with an EF >50%. The difference between flow duration with atrial contraction in the pulmonary veins and transmitral flow duration with atrial contraction correlated with LV filling pressure in both groups.

Conclusions. Analysis of the early diastolic portion of the transmitral or pulmonary venous flow velocity curves can be used to predict LV filling pressures in patients with systolic dysfunction, but are inaccurate in patients with preserved systolic function. The combined analysis of both flow velocity curves at atrial contraction is a reliable, feasible predictor of increased LV filling pressure, irrespective of systolic function.     

Echocardiography in heart failure: applications, utility, and new horizons

Echocardiography is well qualified to meet the growing need for noninvasive imaging in the expanding heart failure (HF) population. The recently-released American College of Cardiology/American Heart Association guidelines for the diagnosis and management of HF labeled echocardiography "the single most useful diagnostic test in the evaluation of patients with HF...," because of its ability to accurately and noninvasively provide measures of ventricular function and assess causes of structural heart disease. It can also detect and define the hemodynamic and morphologic changes in HF over time and might be equivalent to invasive measures in guiding therapy. In this article we will discuss: 1) the clinical uses of echocardiography in HF and their prognostic value; 2) the use of echocardiography to guide treatment in HF patients; and 3) promising future techniques for echocardiographic-based imaging in HF. In addition, we will highlight some of the limitations of echocardiography.     

Ultrasonographic study of left ventricular function at rest in a group of highly trained black African handball players.

AIMS: Most of the studies of athlete's heart have been performed on Caucasian and yet, evidence suggests that there are racial differences in the response of the heart to certain pathological conditions such as hypertension. This study aimed to evaluate the morphologic cardiac changes in a group of highly trained Cameroonian handball players. METHODS AND RESULTS: We studied cardiac morphology and function as assessed by echocardiography at rest in 21 asymptomatic international level handball players and 21 age-, sex-, height- and weight-matched sedentary controls. Echocardiographic variables were compared between groups using unpaired t-test. Compared with controls, wall thickness, relative wall thickness (h/R), left ventricular (LV) mass, LV end diastolic diameter (LVEDD) and left atrial diameter were significantly greater in athletes. None of the athlete exhibited a wall thickness above 12 mm. The ejection fraction (EF) and the mitral pattern on pulsed wave Doppler did not differ in the two groups. CONCLUSIONS: Both LVEDD and wall thickness of elite Cameroonian handball players are increased. There is an increased h/R. The LV EF was normal and not supranormal, as is sometimes believed. These cardiac changes are consistent with cardiac adaptation required in this type of sportsmen who are submitted both in endurance and resistance training.     

Use of Color Kinesis for Evaluation of Left Ventricular Filling in Patients With Dilated Cardiomyopathy and Mitral Regurgitation

Objectives. We tested the feasibility of using analysis of color kinesis images to objectively assess global and regional left ventricular (LV) diastolic function in patients with dilated cardiomyopathy (DCM). In addition, the ability of this technique to track drug-induced changes on LV diastolic properties was studied.

Background. Diastolic dysfunction contributes to symptomatology in patients with DCM. The assessment of LV diastolic function using conventional Doppler echocardiography is indirect and is confounded by multiple variables. Moreover, the noninvasive evaluation of regional diastolic properties is difficult. In contrast, color kinesis directly tracks and color-encodes regional diastolic endocardial motion.

Methods. We studied 24 patients with DCM and mitral regurgitation (MR) and 24 age-matched normal subjects. Transmitral and pulmonary vein flow velocities were measured using pulsed Doppler echocardiography. Diastolic color kinesis images were used to calculate indexes of magnitude and timing of global and regional diastolic function. Diastolic asynchrony was evaluated in different subgroups of patients with DCM. The effects of drug infusions (nitroprusside and dobutamine) were also studied.

Results. Color kinesis indexes of global diastolic function showed significant differences between patients with DCM and normal subjects. Compared with Doppler indexes, color kinesis was less confounded by MR and was capable of differentiating between drug-induced lusitropic and vasodilator effects. Diastolic asynchrony was increased in patients with DCM and severe MR.

Conclusions. Quantitative analysis of global and regional LV diastolic function in patients with DCM using color kinesis is feasible.     

Increased temporal dispersion of myocardial repolarization in myotonic dystrophy type 1: beyond the cardiac conduction system

Objectives

To assess ventricular dysfunction and ventricular interaction after repair of Tetralogy of Fallot (ToF) employing echocardiography speckle-tracking and cardiac magnetic resonance imaging (CMR).

Background

Severe pulmonary regurgitation and right ventricular (RV) dysfunction are common after repair of ToF and may also affect the shape and function of the left ventricle (LV). Recent studies suggest that LV dysfunction may be of particular prognostic value.

Methods and results

Twenty-one consecutive adults with repaired ToF (15 male, mean age 38 ± 11 years, 7 with severe PR) underwent a comprehensive echocardiographic exam including speckle-tracking analysis, CMR and cardiopulmonary exercise testing. Twenty-one subjects without relevant heart disease served as controls. Echocardiographically measured RV diameters correlated with RV volumes obtained from CMR (r = 0.63; p = 0.006). In addition, a close correlation was found between RV and LV function on CMR (r = 0.74, p = 0.002), speckle-tracking LV and RV peak longitudinal 2D strain (r = 0.66, p = 0.003) and mitral and tricuspid annular plain systolic excursion (r = 0.71, p = 0.0003). While LV ejection fraction was normal in the majority of patients and not different from controls, LV longitudinal strain was significantly reduced in ToF patients (− 16.5 ± 3.3 vs. -20.5 ± 2.7%, p = 0.0001).

Conclusion

Left and right ventricular function both by CMR and speckle-tracking is interrelated in adults with repaired ToF. Despite normal LV ejection fraction, 2D longitudinal strain is significantly reduced in ToF patients, suggesting subclinical LV myocardial damage. Considering the potential prognostic value of LV dysfunction in ToF, this measurement may gain importance and should be included in future outcome studies.     

Functional iron deficiency and diastolic function in heart failure with preserved ejection fraction

Background

Functional iron deficiency (FID) is an independent risk factor for poor outcome in advanced heart failure with reduced EF, but its role in heart failure with preserved EF (HFPEF) remains unclear. We aimed to investigate the impact of FID on cardiac performance determined by pressure–volume loop analysis in HFPEF.

Methods

26 HFPEF patients who showed an increase in LV stiffness by pressure–volume (PV) loop analysis obtained by conductance-catheterization, performed exercise testing, echocardiographic examination including tissue Doppler and determination of iron metabolism: serum iron, ferritin and transferrin saturation. HFPEF patients who provided ferritin < 100 μg/l or ferritin of 100–299 μg/l in combination with transferrin saturation < 20% were defined as having FID. In 14 patients the expression of transferrin receptor was determined from available endomyocardial biopsies.

Results

Fifteen out of 26 HFPEF patients showed FID without anemia. Compared to control subjects and HFPEF patients without FID, HFPEF patients with FID showed an up-regulation of the myocardial transferrin receptor expression (p < 0.05). No differences between HFPEF patients with and without iron deficiency were found in heart dimensions, systolic and diastolic function obtained by PV-loop and echocardiography analysis. According to the linear regression analysis, LV stiffness was correlated with peak oxygen uptake (r = − 0.636, p < 0.001) but not with the ferritin level or transferrin saturation. No relation was found between FID and exercise capacity. The association of LV stiffness with exercise performance was independent from the level of iron deficiency.

Conclusion

In non-anemic HFPEF patients, cardiac dysfunction and impaired exercise capacity occur independently of FID.