Biventricular Pacemaker Implantation via the Femoral Vein

We report the case of biventricular pacemaker implantation via the femoral vein, in a patient with impossibility of using standard superior vein approach and a contraindication to epicardial lead placement.

Manifest cardiac memory after biventricular pacing in a super-responder patient: Is memory the sign of a 'forgotten' electrical ventricular pattern?

We present the case of a super-responder patient with a basal left bundle branch block, who underwent cardiac resynchronization therapy and showed, during biventricular pacing, typical electrocardiographic signs of cardiac memory.

Cardiac resynchronization therapy

Systolic heart failure is a major problem for Americans today, with 550,000 new cases diagnosed per year, and ultimately contributes to 287,000 deaths annually. While pharmacologic therapy has drastically improved outcomes in patients with systolic heart failure, hospitalizations from systolic heart failure continue to increase and remain a major cost burden. In response to this unmet need, recent years have seen dramatic improvements in device-based therapy targeting one cause of systolic dysfunction: dyssynchronous ventricular contraction. Cardiac resynchronization therapy aims to restore mechanical synchrony by electrically activating the heart in a synchronized manner. This review summarizes the rationale for cardiac resynchronization therapy, evidence for its use, current guidelines, and ongoing and future directions for research.

Biventricular pacing and heterogeneity of ventricular repolarization in heart failure patients

OBJECTIVE

The aim of our study was to evaluate the effect of cardiac resyncronization therapy (CRT) on QT dispersion (QTd), JT dispersion (JTd) and transmural dispersion of re-polarization (TDR), markers of heterogeneity of ventricular repolarization in a study population with severe heart failure.

METHODS AND RESULTS

Fifty patients (43 male, 7 female, aged 60.2 ± 3.1 years) suffering from congestive heart failure (N = 39 NYHA class III; N = 11 NYHA class IV) as a result of coronary artery disease (N = 19) or of dilated cardiomyopathy (N = 31), sinus rhythm, QRS duration >130 ms (mean QRS duration >156 ± 21 ms), an ejection fraction < 35%, left ventricular end-diastolic diameter >55 mm, underwent permanent biventricular DDDR pacemaker implantation. A 12-lead standard electrocardiogram was performed at baseline, during right-, left-, and biventricular pacing and QTd, JTd and TDR were assessed. Biventricular pacing significantly reduced QTd (73.93 ± 19.4 ms during BiVP vs 91 ± 6.7 ms at sinus rhythm, p = 0.004), JTd (73.18 ± 17.16 ms during BiVP vs 100.72 ± 39.04 at baseline p = 0.003), TDR (93.16 ± 15.60 vs 101.55 ± 19.08 at baseline; p<0.004), as compared to sinus rhythm. Right ventricular endocardial pacing and left ventricular epicardial pacing both enhanced QTd (RVendoP 94 ± 51 ms, p<0.03; LVepiP 116 ±71 ms, p<0.02) and TDR (RVendoP 108.13 ± 19.94 ms; p<0.002; LVepiP 114.71 ± 26.1; p<0.05).There was no effect on JTd during right and left ventricular stimulation.

CONCLUSIONS

Biventricular pacing causes a statistically significant reduction of ventricular heterogeneity of ripolarization and has an electrophysiological antiarrhythmic influence on arrhythmogenic substrate of dilatative cardiomiopathy.

Cardiac resynchronization therapy in congestive heart failure: The state of the art and future perspectives

Congestive heart failure (CHF) is one of the leading causes of morbidity and mortality worldwide. Up to 50% of CHF patients have intraventricular conduction disturbances such as left bundle branch block or nonspecific wide QRS complex on the body surface ECG. Intraventricular conduction delays cause dyssynchrony of the ventricles which in turn leads to regional movement abnormalities and worsening of cardiac function. Recent clinical trials have indicated that cardiac resynchronization therapy or biventricular pacing in CHF patients with left bundle branch block or wide QRS complex improves cardiac function class, exercise tolerance, maximum oxygen consumption and quality of life within the first 12 months of therapy. The number of hospitalizations and the use of intravenous medications for worsening heart failure are also reduced by this new therapy. Apart from the short to medium term clinical benefits, cardiac resynchronization therapy has not been shown to reduce overall cardiac mortality. The present article reviews the pathophysiology of ventricular dyssynchrony and evaluates the results of recent clinical trials on resynchronization therapy.