Effect of resynchronization therapy stimulation site on the systolic function of heart failure patients

BACKGROUND

Cardiac resynchronization therapy (CRT) improves systolic function in heart failure patients with ventricular conduction delay by stimulating the left ventricle (LV) or both ventricles (biventricular, BV). Optimal LV site selection is of major clinical interest for CRT device implantation; however, the dependence of hemodynamics on LV stimulation site has not been established. Thus, the objective of this study was to compare the hemodynamic response to CRT for 2 LV coronary vein sites: the free wall and anterior wall. Methods and Results- A total of 30 patients (mean NYHA class, 2.7; mean QRS interval, 152 ms; mean PR interval, 194 ms) enrolled in the PATH-CHF-II trial were studied. CRT was administered with LV and BV stimulation in VDD mode at 4 AV delays. LV stimulation was at the lateral free wall or anterior wall, whereas right ventricular stimulation was fixed near the apex. LV+dP/dt(max) and aortic pulse pressure changes from baseline during CRT were compared for LV sites. Free wall sites with LV and BV stimulation yielded significantly larger LV+dP/dt(max) (14% versus 6%, P<0.001 for LV; 12% versus 5%, P<0.001 for BV) and pulse pressure (8% versus 4%, P<0.001 for LV; 9% versus 5%, P<0.001 for BV) compared with anterior sites. In one third of patients, CRT at free wall sites increased LV+dP/dt(max), whereas it decreased at anterior sites over most AV delays.

CONCLUSION

CRT with LV free wall stimulation produced significantly better LV systolic performance compared with anterior stimulation. Further studies are warranted to prove the clinical superiority of the LV free wall as a site for long-term CRT.

Should stimulation site be tailored in the individual heart failure patient?

Right ventricular pacing at various sites and shortened atrioventricular (AV) delay has failed to demonstrate a convincing short-term and long-term improvement of left ventricular function. Left-ventricular-based stimulation offers a new therapeutic option for patients with symptomatic congestive heart failure and conduction disturbances, especially of left bundle-branch block configuration. Left ventricular mechanical improvement seems mainly dependent on the pacing site, in addition to optimizing the AV delay. Predominantly retrospective data suggest that pacing the posterolateral free wall results in the greatest hemodynamic improvement. Based on the evaluation of different pacing sites in 2 patients, we noted that site is of major importance for maximal improvement of left ventricular function, and pacing at a suboptimal site can even deteriorate left ventricular contractility. Moreover, lead technology has advanced rapidly and different areas of the left ventricle can now be reached transvenously for acute and chronic placement. Therefore, ongoing trials will help to identify the optimal pacing site and might indicate whether invasive testing will be required in the future.

Echocardiographic evidence of hemodynamic and clinical improvement in patients paced for heart failure

Dilated cardiomyopathy is frequently associated with electrical conduction disturbances. Development of left bundle-branch block with discoordinated ventricular contraction pattern further contributes to impaired hemodynamic performance. Biventricular pacing has evolved as a new treatment option for patients with dilated cardiomyopathy and conduction disturbances. The "electrical" approach aims to normalize the disturbed contraction pattern, thereby improving hemodynamic function by simultaneous stimulation at different ventricular sites. Acute hemodynamic improvement with biventricular pacing has been demonstrated in patients with depressed left ventricular function and delayed intraventricular conduction. Due to the variations in optimal pacing site and atrioventricular delay, individual optimization to achieve optimal hemodynamic benefit is necessary. Echocardiography has the potential to provide hemodynamic data by Doppler techniques and combine these with geometric information about ventricular volumes, ejection fraction, and contraction patterns. This article focuses on the use of echocardiographic techniques for noninvasive optimization in cardiac pacing and presents preliminary experience from the initial trials on multisite pacing in heart failure.

Initial clinical experience with a new small sized third-generation implantable cardioverter defibrillator: results of a multicenter study. European Ventak Mini Investigator Group

This study reports the acute clinical experience with the new CPI VENTAK MINI: a small sized (68 cc), implantable cardioverter defibrillator (ICD) with 33 J stored energy. Implantation of the device was attempted in 113 patients (90 men, mean age 57 +/- 16 years, 64 with coronary artery disease, mean left ventricular ejection fraction 41%) with ventricular tachycardia or ventricular fibrillation (VF). All 113 patients (100%) were ultimately implanted, 12% of them for ICD replacement. Transvenous lead implantation was accomplished in all 104 patients (100%) receiving new leads, 95% of them with a single lead configuration. The safety criteria for implantation (2 consecutive VF conversions at 15 J or 3 at 20 J, in both cases without failures to convert) were demonstrated in all but 7 patients (6%). In 6 of these, safety criteria were not fully assessed while in the last patient defibrillation efficacy was not determined. Of the 104 patients with new leads, 90% underwent pectoral implantation. Of the 9 patients (9%) abdominally implanted, only 4 (4%) (3 children) were judged small sized for pectoral implant. At predischarge testing, reliable VF detection and conversion were noted in 96 of 97 patients tested. There was no perioperative mortality. At a 3.6 +/- 1.3 months follow-up, 34% of the patients had a spontaneous arrhythmic event, and 24% of the patients received shocks. Clinically inappropriate therapies occurred in 8% of the episodes in which any kind of therapy was delivered. This study demonstrates the short-term clinical efficacy and safety of the new device, and that pectoral implantation can be performed in the large majority of patients.