Beneficial effects of biatrial pacing on cardiac function in patients with bradycardia -- tachycardia syndrome

ECG patterns of successful permanent left bundle branch area pacing in bradycardia patients with typical bundle branch block

AIM

To assess the electrocardiogram patterns of paced QRS narrowing after successful left bundle branch area pacing (LBBAP) and echocardiographic measurements in patients with bradycardia and bundle branch block (BBB).

METHODS

We prospectively enrolled 55 consecutive bradycardia patients with BBB and left ventricular ejection fraction ≥40% who had attempted LBBAP. Successful LBBAP was defined as paced QRS morphology of a right BBB (RBBB) pattern in lead V1 and a recording of abruptly shortened and then constant stimulus to peak left ventricular activation time with high and low output. Pacing characteristics and echocardiographic measurements were evaluated perioperatively and at 6-month follow-up.

RESULTS

The success rate of LBBAP was 83.6% in patients with BBB, and median cumulative X-ray dose-area product was 100.5 µGym² (60.0, 179.3). LBBAP was successful in 19 of 26 patients with left BBB (LBBB) (73.1%) and in 27 of 29 patients with RBBB (93.1%). The QRS duration (QRSd) was significantly shortened in patients with LBBB (QRSd 169.4 ± 22.6 to 119.6 ± 9.5 ms), and five forms of QRSd narrowing were observed in patients with RBBB with the mean QRSd shortened from 143.1 ± 16.6 ms to 119.5 ± 11.7 ms. The thresholds for narrowing of QRSd were higher in RBBB than LBBB (1.74 ± 0.36 V/0.4 ms vs 0.79 ± 0.17 V/0.4 ms, P < .001). During the 6-month follow-up, both left and right ventricular synchronies were improved, and narrow QRSd persisted in patients with BBB.

CONCLUSION

In most bradycardia patients, RBBB could be completely or partially narrowed by LBBAP at different pacing models in addition to the correction of LBBB with LBBAP.

Atrioventricular dromotropathy: evidence for a distinctive entity in heart failure with prolonged PR interval?

Heart failure (HF) is often accompanied by atrioventricular (AV) conduction disturbance, represented by prolongation of the PR interval on the electrocardiogram. Studies suggest that PR prolongation exists in at least 10% of HF patients, and it seems more prevalent in the presence of prolonged QRS duration. A prolonged PR interval may result in elevated left ventricular (LV) end-diastolic pressure, diastolic mitral regurgitation, and reduced LV pump function. This seems especially the case in patients with heart disease, in whom it is associated with an increased risk for atrial fibrillation, advanced AV heart block, HF, and death. These findings point towards the importance of proper AV coupling in HF patients. A few studies, strongly differing in design, suggest that restoration of AV coupling in patients with PR prolongation by pacing improves cardiac function and clinical outcomes. These observations argue for AV-dromotropathy as a potential target for pacing therapy, but other studies show inconsistent results. Given its potential clinical implications, restoration of AV coupling by pacing warrants further investigation. Additional possible future research goals include assessing different techniques to measure compromised AV coupling, determine the best site(s) of ventricular pacing, and assess a potential influence of diastolic mitral regurgitation in the efficacy of such therapy.

Cardiac hemodynamics and proinflammatory cytokines during biatrial and right atrial appendage pacing in patients with interatrial block

Purpose

Interatrial block (IAB) frequently coexists with sinus node disease and is considered a risk factor of left atrial dysfunction, atrial arrhythmias, and heart failure development. Conventional right atrial appendage (RAA) pacing impairs intra- and interatrial conductions and consequently prolongs P wave duration. Biatrial (BiA) pacing helps correct IAB, but its advantageous influence remains controversial. The aim of the study was to compare the effects of BiA and RAA pacing on cardiac hemodynamics and serum concentrations of inflammatory markers and neuropeptides.

Methods

Twenty-eight patients with IAB and preserved atrio-ventricular conduction treated with BiA pacing were studied. Standard invasive hemodynamic measurements were performed during BiA and RAA pacings. Furthermore, the influence of 1 week of BiA and RAA pacing on neuropeptides: atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) and markers of inflammation: high sensitivity C-reactive protein (hs-CRP), interleukin 6 (IL-6), and neopterin was examined.

Results

BiA pacing resulted in significant increase of cardiac output (CO) and reduction of pulmonary capillary wedge pressure. We demonstrated significantly lower concentrations of ANP, hs-CRP, IL-6, and neopterin after 1 week of BiA in comparison to RAA pacing. BNP levels remained unchanged.

Conclusions

BiA pacing in comparison to RAA pacing improves hemodynamic performance in patients with IAB and preserved atrio-ventricular conduction. BiA pacing is associated with reduction of ANP and markers of inflammation (hs-CRP, IL-6, and neopterin).

Biatrial pacing improves atrial haemodynamics and atrioventricular timing compared with pacing from the right atrial appendage

AIMS

Patients with interatrial conduction delay may have suboptimal left atrioventricular (AV) timing due to delayed contraction of the left atrium with foreshortening of ventricular filling. This may be an issue in pacemaker patients, especially those requiring resychronization therapy. Pacing from the high interatrial septum (IAS) or the distal or proximal coronary sinus (CSD and CSP) may improve left AV synchrony compared with pacing from the right atrial appendage (RAA). Our aim was to compare haemodynamics of these pacing sites.

METHODS AND RESULTS

A total of 24 patients undergoing radiofrequency ablation for paroxysmal atrial fibrillation were studied. Left atrial pressures were recorded in sinus rhythm, and during pacing from the RAA, IAS, CSD, CSP, and with biatrial (BiA) pacing from the IAS + CSD. Amplitudes, +dP/dT(max), and timing of the a-wave were compared between recordings. Left atrial contractility, measured by +dP/dT(max), was greatest during BiA pacing (P ≤ 0.03 for all comparisons). There was a marked reduction in delay to peak a-wave when pacing from all sites compared with the RAA, with BiA pacing yielding the shortest delay (P ≤ 0.001). However, AV conduction was shortened by all alternative pacing sites, which mitigated the anticipation of left atrial contraction with respect to ventricular activation, except for BiA pacing (P < 0.001). Pacing of the IAS did not result in any improvement in haemodynamics or AV synchrony.

CONCLUSION

Multisite atrial pacing results in favourable acute atrial haemodynamics and left AV synchrony. This may be a solution in pacemaker patients with interatrial conduction delay.

Atrial function during different multisite atrial pacing modalities in patients with bradycardia--tachycardia syndrome

BACKGROUND

Multisite atrial pacing (MAP) was introduced to improve atrial electrical synchrony and prevent recurrence of atrial fibrillation (AF).

METHODS AND RESULTS

In the present study there were 57 patients with sinus node disease, AF recurrence and prolonged P-wave on ECG with 2 MAP modalities. In all patients 1 lead was implanted in the coronary sinus (CS) ostium area. In the right atrial appendage (RAA)+CS group (28 patients) the other atrial lead was in the RAA, and in the BB+CS group (29 patients) in the Bachmann's bundle (BB) region. Tissue Doppler was used to register the electromechanical delay (EMD) in the atrial walls and estimate the atrial contraction synchrony. Cardiac output and myocardial performance index did not differ during the 2 MAP modalities. During BB+CS, in comparison with RAA+CS pacing, the peak of the mitral atrial wave occurred earlier (P<0.01), the usual right-left atrial contraction sequence was reversed more frequently (P<0.004), all atrial EMDs except for the lateral left atrium (LA) were shorter (P<0.05), and LA synchrony was greater (P<0.001).

CONCLUSIONS

In patients treated with MAP, implanting 1 of the atrial leads in the BB area instead of the RAA has no influence on global cardiac hemodynamics, but does result in earlier LA contraction, and reversal of the typical right-left atrial contraction sequence, as well as providing greater LA contraction synchrony.

The role of pacing in rhythm control and management of atrial fibrillation

Atrial fibrillation is the most common sustained cardiac arrhythmia and is increasing in prevalence with an ageing population. As the arrhythmia is often asymptomatic the true prevalence is likely even higher. Largely because of stroke this arrhythmia places a huge financial burden on the health economy. Despite this, large studies assessing rate versus rhythm control have been equivocal. Because of the ineffectiveness of pharmacological therapy much research effort has been undertaken in device and ablative approaches to rhythm management. Although catheter ablation has gained favour because of the high success rates the technique requires considerable expertise and still has a significant complication profile maintaining interest in pacing therapies for atrial fibrillation. Dual chamber versus single-chamber ventricular pacing has been shown to significantly reduce the incidence of atrial fibrillation. Research is currently underway to see if minimising the deleterious effects of right ventricular apical pacing could further increase the benefits of atrioventricular synchronous pacing. Several studies show some (albeit variable) reduction in AF burden with anti-AF algorithms in the setting of bradycardia. Antitachycardia pacing, on the other hand, has not been shown to treat AF in a randomised trial despite the successful termination of co-existent atrial tachycardias. There is increasing evidence that alternative atrial pacing sites may treat AF by improving atrial function. Furthermore, these strategies coupled with other therapies in a 'hybrid approach' have also showed promising results.