Septal lead implantation for the reduction of paced QRS duration using passive-fixation leads

Optimizing the pacing site in the ventricular septum by fluoroscopy and morphology of the paced QRS complex

AIMS

To analyze the paced QRS duration in various septal positions of the right ventricular leads and with different paced QRS vectors. To use the results to assess parameters suggesting the optimal site for right ventricular pacing.

METHODS AND RESULTS

A total of 609 patients with leads implanted in the right ventricular septum were classified using fluoroscopy in the lateral view (the primary pacing site), and in the anteroposterior view (the secondary pacing site), according to the QRS vector in leads I and III. Significantly shortened paced QRS was found in the primary pacing site with the true septal compared with the anteroseptal site, with the vector being negative or isoelectric in lead I plus positive in lead III. In secondary pacing sites, no significant difference in pacing QRS duration was found between RVOT-HS, RVOT-LS, mid-septum and inferior-septum.

CONCLUSIONS

For optimization of the pacing site in the ventricular septum, the following are significant: the primary site based on the lateral view, and the paced QRS vector in leads I and III.

Survival analysis in patients with preserved left ventricular function and standard indications for permanent cardiac pacing randomized to right ventricular apical or septal outflow tract pacing

BACKGROUND

Optimal right ventricular (RV) pacing site in patients referred for permanent cardiac pacing remains controversial. A prospective randomized trial was done to compare long-term effect of permanent RV apex (RVA) vs RV outflow tract (RVOT) pacing on the all-cause and cardiovascular mortality.

METHODS AND RESULTS

A total of 122 consecutive patients (70 men, 69 +/-11 years), with standard pacing indications were randomized to RVA (66 patients) or RVOT (56 patients) ventricular lead placement. After the 10-year follow-up period the mortality data were summarized on the basis of an intention-to-treat analysis. During the long-term follow-up, 31 patients from the RVA group died vs 24 patients in the RVOT group (hazard ratio (HR), 0.96; 95% confidence interval (CI), 0.57-1.65; P=0.89). There were 10 cardiovascular deaths in the RVA and 12 in the RVOT group (HR, 1.04; 95%CI, 0.45-2.41; P=0.93). There were no differences in the all-cause or cardiovascular mortality between the pacing sites after adjustment for age, gender, arterial hypertension, atrial fibrillation, New York Heart Association class and left ventricular end-diastolic diameter.

CONCLUSIONS

The RVOT provides no additional benefit in terms of long-term survival over RVA pacing.

Septal pacing preserving better left ventricular mechanical performance and contractile synchronism than apical pacing in patients implanted with an atrioventricular sequential dual chamber pacemaker

BACKGROUND

Permanent pacing is the treatment for chronotropically incompetent hearts. However, the right ventricular (RV) apical pacing-induced asynchrony, even maintaining the atrioventricular (AV) sequential activation, has depressed left ventricular contractility. Whether RV septal pacing would less compromise the electromechanical performance of the left ventricle and the chronotropic effect on myocardial contractility, is unknown.

METHODS

We prospectively studied 42 patients without structural heart diseases and with symptomatic bradycardia. There were 10 patients receiving atrial pacing (AAI) pacemakers, 18 patients having AV sequential pacing at RV apex (DDDapx) and 14 patients being AV sequentially paced at septum (DDDspt). Echocardiography was performed before and within 72 h after the pacemaker implantation. The ventricular mechanical performance and asynchrony was compared in conditions of programmed rates of 60, 80 and 100/min.

RESULTS

Myocardial performance index was significantly better in DDDspt than in DDDapx patients (p=0.003). With faster programmed rate, the QRS/RR increased (p<0.05) in DDDapx patients with more inter- and intraventricular asynchrony, implicating the disadvantage of prolonged depolarization time. The DDDspt group demonstrated comparable parameters of diastolic function to AAI patients and preserved mechanical performance during accelerated pacing.

CONCLUSIONS

RV septal pacing showed the advantages of shorter depolarization time, less ventricular contractile asynchrony, better mechanical performance and preserved chronotropic response on myocardial contractility in comparison with apical pacing.

A randomized comparison of permanent septal versus apical right ventricular pacing: short-term results

OBJECTIVES

This study compared chronic right ventricular (RV) pacing at the septum versus apex.

BACKGROUND

Chronic RV apical pacing may be detrimental to ventricular function. This randomized, pilot study examined whether, compared with apical, permanent septal pacing preserves cardiac function.

METHODS

Ablation of the atrioventricular junction for permanent AF, followed by implantation of a DDDR pacemaker connected to two ventricular leads was performed in 28 patients. One lead screwed into the septum and another placed at the apex were connected to the atrial and ventricular port, respectively. Septum or apex was paced by programming AAIR or VVIR modes, respectively. Patients were randomly assigned, 4 months later, to pacing at one site for 3 months, and crossed over to the other for 3 months. New York Heart Association class, QRS width and axis, left ventricular ejection fraction (LVEF), exercise duration, and peak oxygen uptake were measured. Results in patients with LVEF > 45% and < or = 45% were compared.

RESULTS

Septal pacing was associated with shorter QRS (145 +/- 4 msec vs 170 +/- 4 msec, P < 0.01) and normal axis (40 degrees +/- 10 degrees vs -71 +/- 4 degrees , P < 0.01). At 3 months, among patients with baseline LVEF < or = 45%, LVEF was 42 +/- 5% after septal pacing versus 37 +/- 4% after apical pacing (P < 0.001).

CONCLUSION

In contrast to RV apical pacing, chronic RV septal pacing preserved LVEF in patients with baseline LVEF < or = 45%.

Upgrade to biventricular pacing in patients with pacing-induced heart failure: can resynchronization do the trick?

Dyssynchrony imposed on ventricular function by right ventricular (RV) apical pacing may lead in some cases to worsening or appearance of heart failure (HF) symptoms. This is a result of an altered pattern of activation, leading to several histological and functional adjustments of the left ventricle, including inhomogeneous thickening of the ventricular myocardium and myofibrillar disarray, fibrosis, disturbances in ion-handling protein expression, myocardial perfusion defects, alterations in sympathetic tone and mitral regurgitation. Studies of mid- and long-term effects of RV apical pacing on left ventricular (LV) function have demonstrated a progressive decline in ejection fraction and other indices of LV functional competence. Upgrading RV pacing systems to biventricular resynchronization modalities is a theoretically promising option for paced patients with worsening HF. The potentially favourable effect of upgrading on LV functional indices and patient clinical status has been demonstrated in few, non-randomized trials. Apart from the scantiness of existing clinical data, issues concerning technical aspects of the procedure and selection of eligible patients are raised. Is pacing-induced dyssynchrony equivalent to the indigenous dyssynchrony in unpaced patients with HF? What selection criteria should be applied in order to identify potential responders to cardiac resynchronization therapy in this patient population? Answers to these and more questions are still lacking.

Biventricular versus conventional right ventricular stimulation for patients with standard pacing indication and left ventricular dysfunction: the Homburg Biventricular Pacing Evaluation (HOBIPACE)

OBJECTIVES

The Homburg Biventricular Pacing Evaluation (HOBIPACE) is the first randomized controlled study that compares the biventricular (BV) pacing approach with conventional right ventricular (RV) pacing in patients with left ventricular (LV) dysfunction and a standard indication for antibradycardia pacing in the ventricle.

BACKGROUND

In patients with LV dysfunction and atrioventricular block, conventional RV pacing may yield a detrimental effect on LV function.

METHODS

Thirty patients with standard indication for permanent ventricular pacing and LV dysfunction defined by an LV end-diastolic diameter > or =60 mm and an ejection fraction < or =40% were included. Using a prospective, randomized crossover design, three months of RV pacing were compared with three months of BV pacing with regard to LV function, N-terminal pro-B-type natriuretic peptide (NT-proBNP) serum concentration, exercise capacity, and quality of life.

RESULTS

When compared with RV pacing, BV stimulation reduced LV end-diastolic (-9.0%, p = 0.022) and end-systolic volumes (-16.9%, p < 0.001), NT-proBNP level (-31.0%, p < 0.002), and the Minnesota Living with Heart Failure score (-18.9%, p = 0.01). Left ventricular ejection fraction (+22.1%), peak oxygen consumption (+12.0%), oxygen uptake at the ventilatory threshold (+12.5%), and peak circulatory power (+21.0%) were higher (p < 0.0002) with BV pacing. The benefit of BV over RV pacing was similar for patients with (n = 9) and without (n = 21) atrial fibrillation. Right ventricular function was not affected by BV pacing.

CONCLUSIONS

In patients with LV dysfunction who need permanent ventricular pacing support, BV stimulation is superior to conventional RV pacing with regard to LV function, quality of life, and maximal as well as submaximal exercise capacity.

Characteristics of Bifocal Pacing:. Right Ventricular Apex versus Outflow Tract. An Interim Analysis

Bifocal RIGHT ventricular stimulation (BRIGHT) is an ongoing, randomized, single-blind, crossover study of atrial synchronized bi-right ventricular (RV) pacing in patients in New York Heart Association heart failure functional class III, a left ventricular ejection fraction <35%, left bundle branch block and QRS complexes >/=120 ms. This analysis compared the electrical and handling characteristics, and the complications of pacing at the RV apex (Ap) with passive, versus RV outflow tract (OT) with active fixation leads. A mean of 1.6 +/- 0.9 and 2.2 +/- 2.0 attempts were needed to position the Ap and OT leads, respectively (ns). R-wave amplitudes at Ap versus OT were 23 +/- 13 mV versus 14 +/- 8 mV (n = 36, P < 0.001). R-wave amplitudes at the Ap remained stable between implant and M7. R-wave amplitudes at the OT could not be measured after implantation. In two patients, atrioventricular block occurred during active fixation at the OT. Conduction recovered spontaneously within 4 months. Ventricular fibrillation was induced in one patient during manipulation of an Ap lead in the RV. Marked differences were found between leads positioned in the OT versus Ap, partly related to the difference in lead design. Mean R-wave amplitude was higher at the Ap that at the OT. Ease and success rate of lead implant was similar in both positions.