http://tamthuvn.com/Reprints/BaldasseroniCHFLBB2002.pdf

Left bundle-branch block is associated with increased 1-year sudden and total mortality rate in 5517 outpatients with congestive heart failure: a report from the Italian network on congestive heart failure.

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/dtmax and aortic pulse pressure changes from baseline during CRT were compared for LV sites. Free wall sites ...

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

Background— Although dual-chamber pacing improves cardiac function in patients with complete congenital atrioventricular block (CCAVB) by restoring physiological heart rate and atrioventricular synchronization, the long-term detrimental effect of asynchronous electromechanical activation induced by apical right ventricular pacing (RVP) has not been well clarified. Methods and Results— Twenty-three CCAVB adults (24±3 years) with a DDD transvenous pacemaker underwent conventional echocardiography before implantation and, after at least 5 years of RVP, an exercise test and echocardiography coupled with tissue Doppler imaging and tissue tracking. They were compared with 30 matched healthy control subjects. After 10±3 years of RVP, CCAVB adults had significantly higher values versus controls in terms of intra-left ventricular (LV) asynchrony (respectively, 59±18 versus 19±9 ms, P<0.001), extent of LV myocardium displaying delayed longitudinal contraction (39±15% versus 10±7%, P<0.01), and septal-to-posterior w...

Detrimental Ventricular Remodeling in Patients With Congenital Complete Heart Block and Chronic Right Ventricular Apical Pacing

Background:

recent short-term observations have shown an improvement in cardiac function and heart failure symptoms from atrio-biventricular pacing. This study was designed to assess the safety and feasibility of an atrio-biventricular transvenous pacing system, and examine the long-term effects of cardiac resynchronization in patients with advanced heart failure and ventricular conduction abnormalities.



Methods and results:

between August, 1997 and November, 1998, 103 patients received a cardiac resynchronization system (CRS) consisting of a pulse generator interfaced with an atrio-biventricular lead system, including a lead designed for left ventricular (LV) pacing via cardiac veins. Baseline evaluation included 12-lead electrocardiogram, estimation of New York Heart Association (NYHA) functional class, assessment of quality of life (QOL), and distance covered during a 6-min walk (6-MW). Detailed echocardiographic data were also collected in a subset of 46 patients. Measurements were repeated in all surviving patients at 1, 3, 6 and 12 months after implantation of the CRS. A single, self-limiting procedure-related complication occurred. Over a follow-up of 12 months, 21 patients died. The 12-month actuarial survival was 78% (CI 70–87%). Nine surviving patients were withdrawn from the study during long-term follow-up for miscellaneous reasons. At each point of follow-up, a significant shortening of QRS duration was measured. In addition, significant improvements were observed in mean NYHA functional class, 6-MW and QOL score. In the 46 patients with complete echocardiographic data, LV ejection fraction increased from 21.7±6.4% at baseline to 26.1±9.0% at last follow-up (P-0.006), LV end diastolic dimension decreased from 72.7±9.2 to 71.6±9.1 mm (P-0.233), interventricular mechanical delay decreased from 27.5±32.1 to 20.3±25.5 ms (P-0.243), mitral regurgitation apical four-chamber area decreased from 7.66±5.5 to 6.69±5.9 cm2 (P-0.197), and left ventricular filling time increased from 363±127 to 408±111 ms (P-0.002).



Conclusions:

long-term cardiac resynchronization can be safely and reliably achieved by transvenous atrial synchronized right and left ventricular pacing. These changes were accompanied by clinically relevant improvements in functional status and QOL, as well as a measurable increase in LV performance. The outcome of randomised controlled trials is awaited.

Cardiac resynchronization therapy in advanced heart failure the multicenter InSync clinical study.

Echocardiographic parameters of ventricular dyssynchrony validation in patients with heart failure using sequential biventricular pacing.

Cardiac electrical stimulation as primary or adjunctive treatment of congestive heart failure is entering its second decade of existence Initial trials of conventional DDD pacing1-5 were followed by bifocal right ventricular stimulation6 The concept of multisite stimulation for haemodynamic support was introduced in 19947 8 Various studies have already reported the benefits of this method,9 10 or are in progress11 

The transition from conventional DDD pacing to multisite stimulation was not fortuitous Successive “advances” in the design of cardiac pacing systems have aimed at correcting anomalies in the sequence of cardiac chamber activation, as well as in the synchronisation of the various phases of myocardial contraction and relaxation The phenomenon of asynchrony is a consequence of progressive, global or focal degradation of the myocardium One can easily visualise interstitial fibrosis gradually replacing areas of normal myocardium, and causing heterogeneous propagation of cardiac electrical activity Such heterogeneity combines, to various degrees, three consecutive atrioventricular, interventricular, and intraventricular asynchrony levels Among various analytical and modelling methods, Doppler echocardiography is preferred for its ease of application in day to day practice12 

The oldest concept, that of desynchronised atrioventricular sequential activation, applies only to sinus rhythm It is the product of a mismatch between end of atrial systole and onset of ventricular systole, sometimes facilitated by a disorder of atrioventricular conduction or QRS prolongation It may be simply described as an abbreviated ventricular filling time with respect to the complete cardiac cycle, and, on occasion, by early passive ventricular filling flow superimposed on atrial systole dependent flow Dual chamber pacing, by linking ventricular to atrial activation, normalises flow patterns of ventricular filling, provided atrial contraction …

https://heart.bmj.com/content/heartjnl/84/6/579.full.pdf

J Mugica

Papers

Multisite stimulation for correction of cardiac asynchrony