Acute effects of intraoperative multisite ventricular pacing on left ventricular function and activation/contraction sequence in patients with depressed ventricular function
ABSTRACT We hypothesized that simultaneous right and left ventricular apical pacing would result in improvement in left ventricular function due to improved coordination of segmental ventricular contraction. Structural changes in ventricular muscle present in dilated cardiomyopathy compromise ventricular excitation and mechanical contraction. METHODS and
Eleven patients with depressed left ventricular function having cardiac surgery underwent epicardial multisite pacing with continuous transesophageal echocardiographic imaging. Quantitative measurement of percent fractional area change was performed, and segmental changes in contraction sequence resulting from simultaneous right and left ventricular pacing were assessed by application of phase analysis to recorded transesophageal images. There was no statistically significant difference between the paced QRS duration achieved with simultaneous right and left ventricular apical pacing and the native QRS duration (139+/-39 msec vs 106+/-18 msec, P = NS), but all other paced modes resulted in longer QRS durations. Percent fractional area change improved with simultaneous right and left ventricular apical pacing but not with other paced modes (41.5+/-11.9 vs 34.3+/-9.7, P < 0.01). Phase analysis demonstrated a resequencing of segmental left ventricular activation/contraction when compared to baseline ventricular activation.
Simultaneous right and left ventricular apical pacing results in acute improvements in global ventricular performance in patients with depressed ventricular function. Improvements may result from pacing-induced global coordination through recruitment of left and right ventricular apical and septal segments critical to effective ventricular contraction.
SourceAvailable from: Juan Senior
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ABSTRACT: Congestive heart failure afflicts 2 to 4 million people in the US and nearly 15 million people worldwide. Accepted goals of heart failure treatment include: (i) improvement of symptoms; (ii) prevention of disease progression; and (iii) reduction in morbidity and mortality. Complex pharmacological therapies achieve these goals, but not in all patients with heart failure. Cardiac resynchronization therapy (CRT) represents a new therapeutic approach in patients with chronic heart failure. CRT is only applicable to a subgroup of patients with ventricular conduction system delay, characterized by prolonged QRS duration. Bundle branch block impacts 20 to 30% of patients with New York Heart Association (NYHA) functional class III–IV heart failure and consists predominantly of left bundle branch block. When left ventricular (LV) conduction delay is superimposed upon ventricular dysfunction, it appears to be a marker of disease severity. These conduction abnormalities have deleterious effects both on systolic function and LV filling, and they can induce or enhance mitral functional regurgitation. CRT attempts to correct the deleterious effect of dysynchrony by increasing LV filling time, decreasing septal dyskinesis and reducing mitral regurgitation. Several observational studies and randomized, controlled trials have shown the benefit of CRT in a subgroup of patients with heart failure, with conduction delays. Improvements were found in the mean distance walked in 6 minutes, quality of life (QOL), NYHA functional class, in peak oxygen uptake (V̇O2), total exercise time, reduction of hospitalization, LV function and reduction of the LV end-diastolic diameter. These studies support the therapeutic value of ventricular resynchronization in patients with severe heart failure, who have intraventricular conduction delay but who do not have a standard indication for the implantation of a pacemaker. In respect to these study results, possible indications for a biventricular pacing device at this time are as follows: NYHA functional class III, LV ejection fraction <35%, sinus rhythm, QRS duration >150 msec and drug refractory despite individual optimal heart failure therapy. CRT significantly improved symptoms, exercise tolerance and QOL in most patients. However, further studies are needed to assess long-term clinical effects and prognosis, as well as economic benefit of this therapeutic approach.American Journal of Cardiovascular Drugs 01/2002; 2(4). DOI:10.2165/00129784-200202040-00001 · 2.20 Impact Factor
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ABSTRACT: Objectives This study sought to examine whether suppressing premature ventricular contractions (PVC) using radiofrequency ablation improves effectiveness of the cardiac resynchronization therapy (CRT) in nonresponders. Background CRT is an effective strategy for drug refractory congestive heart failure. However, one-third of patients with CRT do not respond clinically, and the causes for nonresponse are poorly understood. Whether frequent PVC contribute to CRT nonresponse remains unknown. Methods In this multicenter study, CRT nonresponders with >10,000 PVC in 24 h who underwent PVC ablation were enrolled from a prospective database. Results Sixty-five subjects (age 66.6 ± 12.4 years, 78% men, QRS duration of 155 ± 18 ms) had radiofrequency ablation of PVC from 76 foci. Acute and long-term success rates of ablation were 91% and 88% in 12 ± 4 months of follow-up. There was significant improvement in left ventricular (LV) ejection fraction (26.2 ± 5.5% to 32.7 ± 6.7 %, p < 0.001), LV end-systolic diameter (5.93 ± 0.55 cm to 5.62 ± 0.32 cm, p < 0.001), LV end-diastolic diameter (6.83 ± 0.83 cm to 6.51 ± 0.91 cm, p < 0.001), LV end-systolic volume (178 ± 72 to 145 ± 23 ml, p < 0.001), LV end-diastolic volume (242 ± 85 ml to 212 ± 63 ml, p < 0.001), and median New York Heart Association functional class (3.0 to 2.0, p < 0.001). Modeling of pre-ablation PVC burden revealed an improvement in ejection fraction when the pre-ablation PVC burden was >22% in 24 h. Conclusions Frequent PVC is an uncommon yet significant cause of CRT nonresponse. Radiofrequency ablation of PVC foci improves LV function and New York Heart Association class and promotes reverse remodeling in CRT nonresponders. PVC ablation may be used to enhance CRT efficacy in nonresponders with significant PVC burden.Journal of the American College of Cardiology 10/2012; 60(16):1531–1539. DOI:10.1016/j.jacc.2012.06.035 · 15.34 Impact Factor