Echocardiographic Assessment During Exercise of Heart Failure Patients With Cardiac Resynchronization Therapy (original) (raw)
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Journal of the American College of Cardiology, 2002
OBJECTIVES We sought to compare the short-and long-term clinical effects of atrial synchronous pre-excitation of one (univentricular) or both ventricles (biventricular), that provide cardiac resynchronization therapy (CRT). BACKGROUND In patients with heart failure (HF) who have a ventricular conduction delay, CRT improves systolic hemodynamic function. The clinical benefit of CRT is still being investigated. METHODS Forty-one patients were randomized to four weeks of first treatment with biventricular or univentricular stimulation, followed by four weeks without treatment, and then four weeks of a second treatment with the opposite stimulation. The best CRT stimulation was continued for nine months. Cardiac resynchronization therapy was optimized by hemodynamic testing at implantation. The primary end points were exercise capacity measures. Data were analyzed by two-way repeated-measures analysis of variance. RESULTS The left ventricle was selected for univentricular pacing in 36 patients. The clinical effects of univentricular and biventricular CRT were not significantly different. The results of each method were pooled to assess sequential treatment effects. Oxygen uptake during bicycle exercise increased from 9.48 to 10.4 ml/kg/min at the anaerobic threshold (p ϭ 0.03) and from 12.5 to 14.3 ml/kg/min at peak exercise (p Ͻ 0.001) with the first treatment, and from 10.0 to 10.7 ml/kg/min at the anaerobic threshold (p ϭ 0.2) and from 13.4 to 15.2 ml/kg/min at peak exercise (p ϭ 0.002) with the second treatment. The 6-min walk distance increased from 342 m at baseline to 386 m after the first treatment (p Ͻ 0.001) and to 416 m after the second treatment (p ϭ 0.03). All improvements persisted after 12 months of therapy. CONCLUSIONS Cardiac resynchronization therapy produces a long-term improvement in the clinical symptoms of patients with HF who have a ventricular conduction delay. The differences between optimized biventricular and univentricular therapy appear to be small for short-term treatment.
Circulation, 2002
Background-Biventricular pacing has been proposed to improve symptoms and exercise capacity in patients with advanced heart failure and wide electrocardiographic wave complexes. This study investigated the effect of biventricular pacing on reverse remodeling and the underlying mechanisms. Methods and Results-Twenty-five patients with NYHA class III to IV heart failure and electrocardiographic wave complex duration Ͼ140 ms receiving biventricular pacing therapy were assessed serially up to 3 months after pacing and when pacing was withheld for 4 weeks. Tissue Doppler echocardiography was performed using a 6-basal, 6-mid segmental model to assess the time to peak sustained systolic contraction (T S). There was significant improvement of ejection fraction, dP/dt, and myocardial performance index; decrease in mitral regurgitation, left ventricular (LV) end-diastolic (205Ϯ68 versus 168Ϯ67 mL, PϽ0.01) and end-systolic volume (162Ϯ54 versus 122Ϯ42 mL, PϽ0.01); and improved 6-minute hall-walk distance and quality of life score after pacing for 3 months. The mechanisms of benefits were as follows: (1) improved LV synchrony, as evident by homogeneous delay of T S to a timing close to the latest (usually the lateral) segment abolishing the intersegmental difference in T S and decreasing the standard deviation of T S within the left ventricle (37.7Ϯ10.9 versus 29.3Ϯ8.3 ms, PϽ0.05); (2) improved interventricular synchrony; and (3) shortened isovolumic contraction time (122Ϯ57 versus 82Ϯ36 ms, PϽ0.05) but increased diastolic filling time. These benefits are pacing dependent, because withholding the pacing resulted in varying speeds in the loss of cardiac improvements. Conclusions-Biventricular pacing reverses LV remodeling and improves cardiac function. Improvement of LV mechanical synchrony seems to be the predominant mechanism. (Circulation. 2002;105:438-445.
Journal of the American College of Cardiology, 2003
on behalf of the Multisite Stimulation in Cardiomyopathy (MUSTIC) Study Group London, United Kingdom; and Rennes, France OBJECTIVES We sought to assess the efficacy of biventricular pacing with respect to both peak and submaximal measures of exercise in patients with New York Heart Association class III heart failure (HF) and intraventricular conduction delay in a randomized, blinded study. BACKGROUND Submaximal and maximal changes in exercise capacity need evaluating in this patient population with this novel therapy.
2010
on behalf of the Multisite Stimulation in Cardiomyopathy (MUSTIC) Study Group London, United Kingdom; and Rennes, France OBJECTIVES We sought to assess the efficacy of biventricular pacing with respect to both peak and submaximal measures of exercise in patients with New York Heart Association class III heart failure (HF) and intraventricular conduction delay in a randomized, blinded study. BACKGROUND Submaximal and maximal changes in exercise capacity need evaluating in this patient population with this novel therapy.
Mechanisms by Which Cardiac Resynchronization Therapy Improves Cardiac Performance in Heart Failure
Journal of the American College of Cardiology, 2011
This thesis assesses the mechanisms by which biventricular and left ventricular pacing improves cardiac performance in patients with heart failure. We demonstrated for the first time that CRT results in an improvement in acute haemodynamic variables in heart failure patients with a narrow QRS duration that is comparable to the effects seen in heart failure patients with a broad QRS duration. In addition, we have shown that both biventricular (BIVP) and left ventricular pacing (LVP) significantly reduce external constraint to left ventricular filling, resulting in an increase in effective filling pressure. In heart failure patients with evidence of external constraint at rest, the acute haemodynamic benefits of both BIVP and LVP were principally due to the relief of external constraint and preload recruitment. However, in those patients with evidence of electrical dyssynchrony and a broad QRS duration, a significant haemodynamic benefit was derived from an enhancement in left ventricular contractility, presumably as a result of a reduction in left ventricular dyssynchrony. Patients with external constraint appear to derive a greater haemodynamic benefit from pacing due to the significant increase in stroke work that is associated with relief of external constraint and preload recruitment, in addition to the increase in stroke work derived from enhanced contractility due to a reduction in dyssynchrony. These findings will inform better patient selection for this therapy and also optimisation of pacing strategy in individual patients. STATEMENT OF CONTRIBUTION I undertook screening (with echocardiography, ECG and metabolic exercise testing) and recruitment of potential participants with a narrow QRS duration, as well as recruiting patients undergoing implantation of a biventricular pacemaker with a broad QRS duration. I undertook the acquisition of the invasive haemodynamic data in 85% of all patients, and completed analysis of the data in all cases recruited. I was also involved in the collection and analysis of all echocardiographic data included in this thesis.
Canadian Journal of Cardiology, 2008
INTRODUCTION: Mitral regurgitation (MR) in chronic heart failure (CHF) patients frequently worsens with exercise. Cardiac resynchronization therapy (CRT) reduces MR at rest, but its effects on exercise-induced worsening of MR are incompletely explored. The present study examined the influence of CRT on MR during submaximal exercise in CHF patients. METHODS: Eleven patients with CHF who were treated with CRT underwent echocardiography while performing steady-state exercise during four conduction modes (intrinsic rhythm, right ventricular [RV], biventricular [BiV] and left ventricular [LV] pacing). Measurements of MR were jet area planimetry, effective regurgitant orifice area, peak MR flow rate and regurgitant volume. RESULTS: At rest and during exercise, there were no differences in dyssynchrony between intrinsic rhythm and RV pacing. BiV and LV pacing reduced dyssynchrony at rest and during exercise compared with intrinsic conduction and RV pacing, and there were no differences in the magnitude of these effects between these two pacing modes. At rest, RV pacing increased MR compared with intrinsic conduction (MR regurgitant volume; P<0.05), whereas BiV and LV pacing reduced MR (reductions in effective regurgitant orifice area and jet area; P<0.02, and MR flow rate; P<0.05 with BiV pacing from intrinsic conduction). MR significantly increased on exercise with intrinsic rhythm and RV pacing, whereas with LV and BiV pacing, there were no significant exercise-induced increases in any MR variable. There were relationships between changes in measures of dyssynchrony and reductions in MR at rest and during exercise. CONCLUSIONS: CRT reduces MR at rest and during exercise, and prevents exercise-induced MR. Reductions in MR during exercise correlate with improvements in dyssynchrony.
Journal of the American College of Cardiology, 2001
We sought to investigate the impact of six months of cardiac resynchronization therapy (CRT) on echocardiographic variables of left ventricular (LV) function. BACKGROUND Cardiac resynchronization therapy has recently been introduced as a new therapeutic modality in patients with advanced heart failure (HF) and conduction abnormalities. However, most studies have only investigated the early hemodynamic effects of CRT. METHODS Twenty-five patients (12 women and 13 men; 59.8 Ϯ 5.1 years old) with advanced HF caused by ischemic (n ϭ 7) or idiopathic dilated cardiomyopathy (n ϭ 18) and a prolonged QRS complex were analyzed. All patients underwent early hemodynamic testing with a randomized testing protocol; echocardiographic measurements were compared before implantation and after six months of CRT. RESULTS Left ventricular end-diastolic and end-systolic diameters (LVEDD and LVESD, respectively) were significantly reduced after six months (LVEDD from 71 Ϯ 10 to 68 Ϯ 11 mm, p ϭ 0.027; LVESD from 63 Ϯ 11 to 58 Ϯ 11 mm, p ϭ 0.007), as were LV end-diastolic and end-systolic volumes (LVEDV from 253 Ϯ 83 to 227 Ϯ 112 ml, p ϭ 0.017; LVESV from 202 Ϯ 79 to 174 Ϯ 101 ml, p ϭ 0.009). Ejection fraction was significantly increased (from 22 Ϯ 7% to 26 Ϯ 9%, p ϭ 0.03). "Nonresponders," with regard to LV volume reduction, had significantly higher baseline LVEDV, compared with "responders" (351 Ϯ 52 vs. 234 Ϯ 74 ml, p ϭ 0.018). Overall, there was only mild mitral regurgitation at baseline, with a minor reduction by semiquantitative analysis. The results of early hemodynamic testing did not predict the volume response. CONCLUSIONS Cardiac resynchronization therapy may lead to a reduction in LV volumes in patients with advanced HF and conduction disturbances. Volume nonresponders have significantly higher baseline LVEDV.
… England Journal of …, 2001
Nine patients were withdrawn from the study before randomization, and 10 failed to complete both study periods. Thus, 48 patients completed both phases of the study. The mean (±SD) distance walked in six minutes was 23 percent greater with active pacing (399±100 m vs. 326±134 m, P<0.001), the qualityof-life score improved by 32 percent (P<0.001), peak oxygen uptake increased by 8 percent (P<0.03), hospitalizations were decreased by two thirds (P<0.05), and active pacing was preferred by 85 percent of the patients (P<0.001).