The importance of avoiding unnecessary right ventricular pacing in clinical practice

Transcatheter Aortic Valve Implantation: Addressing the Subsequent Risk of Permanent Pacemaker Implantation

Transcatheter aortic valve implantation (TAVI) is now a commonly used therapy in patients with severe aortic stenosis, even in those patients at low surgical risk. The indications for TAVI have broadened as the therapy has proven to be safe and effective. Most challenges associated with TAVI after its initial introduction have been impressively reduced; however, the possible need for post-TAVI permanent pacemaker implantation (PPI) secondary to conduction disturbances continues to be on the radar. Conduction abnormalities post-TAVI are always of concern given that the aortic valve lies in close proximity to critical components of the cardiac conduction system. This review will present a summary of noteworthy pre-and post-procedural conduction blocks, the best use of telemetry and ambulatory device monitoring to avoid unnecessary PPI or to recognize the need for late PPI due to delayed high-grade conduction blocks, predictors to identify those patients at greatest risk of requiring PPI, important CT measurements and considerations to optimize TAVI planning, and the utility of the MInimizing Depth According to the membranous Septum (MIDAS) technique and the cusp-overlap technique. It is stressed that careful membranous septal (MS) length measurement by MDCT during pre-TAVI planning is necessary to establish the optimal implantation depth before the procedure to reduce the risk of compression of the MS and consequent damage to the cardiac conduction system.

Electrophysiological demonstration of nonselective His-Purkinje system capture with para-Hisian pacing

BACKGROUND

The adverse effects of conventional right ventricular (RV) apical pacing prompted the search for more physiological pacing sites, such as selective and nonselective His bundle pacing (HBP), a variant of nonselective HBP (para-Hisian pacing), and mid-septal pacing. However, knowledge of their true benefit on the physiology of ventricular activation, lead stability, and pacing thresholds is limited.

METHODS AND RESULTS

We included 152 consecutive patients (mean age 61 ± 24, 63% men) in this retrospective study. Of these, 137 patients with different bradyarrhythmias underwent active fixation lead implantation at the RV apex (n = 54), para-Hisian region (n = 66), or mid interventricular septum (n = 17). Fifteen patients with ventricular preexcitation due to an accessory pathway not undergoing pacing were included as controls. A 12‑lead ECG was recorded in all patients, and cardiac electrical synchrony was assessed using the Synchromax® cross-correlation cardiac synchrony index (CSI).

RESULTS

QRS duration was prolonged in all pacing sites: from 114 ± 28 to 160 ± 29 (RV apex), from 110 ± 28 to 122 ± 29 (para-Hisian), and from 121 ± 24 to 154 ± 30 (mid interventricular septum). The CSI was significantly improved only in patients undergoing para-Hisian pacing, despite a slight widening of the QRS interval. There was no difference in pacing thresholds and sensed R-wave voltage between pacing sites. Only 1 lead, implanted at the para-Hisian region (1.5%), was dislodged towards the mid septum 48 h after implantation but did not require repositioning.

CONCLUSIONS

QRS duration was not associated with changes in CSI, meaning that QRS width does not significantly affect electrical synchrony.

Chronology of cardiac dysfunction after permanent pacemaker implantation: an observational 2 year prospective study in North India

Background

The purpose of this study is to evaluate cardiac functions using transthoracic echocardiography, change in lead parameters and electrocardiogram (ECG) morphology in patients undergoing permanent pacemaker implantation over a follow-up period of 6 months.

Methods

This is a prospective study in patients undergoing permanent pacemaker implantation in a tertiary care hospital. Patients undergoing permanent pacemaker implantation were enrolled for up to one year and Echocardiographic parameters (by 2 blind operators) and ECG parameters were recorded at admission (within 24 h), before discharge (within 7 days of pacemaker implantation), after 1 month (± 7 days) and after 6 months (± 7 days) of follow-up.

Results

A total of 96 patients (60.4% males and 39.6% female, mean age 66.65 years) were implanted with permanent pacemaker. The mean QRS duration was 133.18 ms and increased significantly to 146.03 ms by 6 months despite septal lead placement in majority (92%) of patients. The mean baseline ejection fraction of 51.47 decreased significantly to 47.83 by 6 months. Diastolic parameters like left atrial volume index, early to late diastolic transmitral flow velocity (E/A) and early diastolic mitral annular tissue velocity (E/e′) showed a significant increase (> 5%) from baseline by the end of first week. By the end of first month, systolic dysfunction of RV sets in with significant (> 5%) change from baseline in parameters like Right ventricle myocardial performance index, transannular plane systolic excursion and right ventricle systolic excursion velocity (RVS′).

Conclusion

We have observed that pacemaker recipients with baseline reduced left ventricle (LV) systolic functions perform significantly worse compared to those with baseline normal cardiac functions and had a higher rate of deterioration of LV function. RV dysfunction is the first abnormality that occurs, by 1 week followed by LV dysfunction which starts by 1 month and the diastolic dysfunctions precede the systolic dysfunction. QRS duration also showed a gradual increase despite septal lead placement in majority (92%) and lead parameters showed no significant change over 6 months.

Effects of cardiac pacemakers on left ventricular volumes and function assessed by 3D echocardiography, Doppler method, and global longitudinal strain

Background

Many previous studies reported the negative effects of right ventricular (RV) pacing on the left ventricular (LV) structure and ejection fraction. Studying pacing hemodynamics is essential to understand these detrimental effects. In this study, we tried to understand RV pacing effects on LV volumes and function using advanced tools like 3D echo and global longitudinal strain (GLS). This was a prospective study of 175 consecutive patients (LVEF>50%) presented permanent pacing. Of 175 patients, only 50 patients met study criteria, divided into two groups (single or dual pacing). LV volumes and function were assessed by full-volume 3D echocardiography and GLS before pacing, at 1-week and 6-month post-pacing. Cardiac output (COP) was calculated by pulsed wave Doppler method and 3D echo.

Results

Doppler method results were similar to 3D echo in calculating SV and COP. At 1-week post pacing, both groups showed a significant decrease in SV due to a drop in EDV while ESV did not change significantly. Despite the drop in SV, there was a significant increase in cardiac output (COP) due to achieving higher heart rates post-pacing. There was a significant drop in EF and GLS in both groups.

At 6 months, SV continued to decrease with a corresponding decrease in COP and LVEF. This drop in SV was due to a significant increase in ESV while EDV did not show a significant change at a 6-month follow-up. Also, the drop EF and GLS became more significant.

There were no significant differences between both groups regarding the changes in LV volumes (EDV, ESV, SV), LVEF or GLS throughout the study (pre-pacing, at 1-week and 6-months post pacing). However, dual-chamber pacing group provided higher heart rates and as a result higher COP than the single-chamber group.

Conclusions

RV pacing led to a significant drop in LV COP, ejection fraction (EF), and GLS over short- and long-term duration. Dual chamber pacing provided higher COP than a single chamber pacing. This was due to tracking the S. A node with pacing at higher heart rates not due to an increase in SV and preserving atrioventricular synchrony. Both Doppler method and 3D echo can be used to calculate SV and COP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43044-021-00138-9.

Predictors of pacing induced left ventricular dysfunction and cardiomyopathy assessed by three-dimensional echocardiography and speckle tracking strain

Background

Long-term RV pacing leads to ventricular dyssynchrony, in the form of LBBB-like morphology, with subsequent detrimental effects on LV structure and function. Three-dimensional echocardiography allowed early detection of volumetric changes associated with PICMP and provided more accurate assessment of mechanical dyssynchrony. Speckle tracking strain is able to identify LV dysfunction even before any reduction in LVEF. Our aim was to study pacing effects on LV function and hemodynamics using 3D echo and speckle tracking strain.

Results

This was a prospective study of 175 consecutive patients without structural heart disease (LVEF > 50%) presented for permanent pacing. Full-volume 3D echocardiography done before implantation, 1 week, and 6 months together with GLS. Patients were followed for 6 months to detect incidence of PIVD (defined as reduction in LVEF > 10% but still above 50%) and PICMP (defined as decrease in LVEF by 10% from baseline in absence of other known causes of cardiomyopathy resulting in EF< 50%). PIVD and PICMP predictors and risk factors were analyzed. Only 50 patients met study criteria. Twenty-five (50%) patients developed LV systolic dysfunction; of these, 19 (38%) developed PIVD and 6 (12%) developed PICMP. Pre-implantation GLS was significantly lower in the 6 patients who subsequently developed PICMP, compared to those who developed PIVD and the preserved EF group (mean GLS − 15.50 vs. − 21.0, − 20.0 respectively; p = 0.005, 0.033, respectively). At 1 week, GLS was significantly lower in the 25 patients who subsequently developed PIVD, compared to those who did not (GLS − 13.0 vs. − 18.0, respectively; p = 0.002). A reduction of baseline GLS by 15% or more at 1 week was associated with the development of PIVD and PICMP (p = < 0.001). A wider native QRS complex was associated with PIVD and PICMP (p = 0.008, 0.018, respectively). The other predictors were found non-significant.

Conclusion

PICMP may be more common than previously reported and it may occur shortly after implantation. Pre-implantation GLS is a sensitive parameter for PICMP. One-week GLS, pre-implantation QRS complex width are early predictors for PICMP and PIVD before any reduction in EF.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43044-021-00136-x.

Does Minimizing Ventricular Pacing Reduce the Incidence of Atrial Fibrillation? A Systematic Review and Meta-analysis of Randomized Controlled Trials

Background: Right ventricular pacing disrupts atrioventricular synchrony and increases the risk of atrial fibrillation (AF). However, whether algorithms for minimizing ventricular pacing reduce the incidence of AF remains controversial. Therefore, we conducted a systematic review and meta-analysis to compare the incidence of AF between minimizing ventricular pacing and conventional pacing protocols in patients with pacemakers implanted.Methods: The PubMed, Embase, and Cochrane Library databases were searched up to August 1, 2017, for randomized controlled trials that reported the incidence of AF in patients with and without the use of algorithms for minimizing ventricular pacing.Results: Eleven studies comprising 5705 participants (61% males, mean age 71 years [standard deviation 11 years]) were finally included in the analysis. The mean follow-up duration was 24 months. Use of algorithms for minimizing ventricular pacing significantly reduced the incidence of AF, with an odds ratio of 0.74 (95% confidence interval 0.55‐1.00; P<0.05). There was moderate heterogeneity among studies (I2=63%).Conclusions: The incidence of AF was reduced by 26% with use of algorithms for minimizing ventricular pacing. The incorporation of such algorithms in routine clinical practice should in theory lead to a decrease in AF-related morbidity and mortality.

Electrocardiographic interpretation of pacemaker algorithms enabling minimal ventricular pacing

Cardiac pacing from the apex of the right ventricle has been shown to result in left ventricular dysfunction, atrial fibrillation, and increased mortality. To counter these effects, one of the strategies developed is avoidance of ventricular pacing when not necessary, using programmable algorithms to minimize ventricular pacing. Seven algorithms are available from 5 manufacturers. Four of the manufacturers have mode conversion algorithms that pace AAI(R) but, in the presence of failed atrioventricular (AV) conduction, demonstrate algorithm-offset and convert to DDD(R) with ventricular pacing. Three manufacturers do not have mode conversion but rather AV extension to encourage AV conduction. Each of these algorithms has a unique design and, when ventricular pacing is present, will regularly schedule conduction testing to encourage AV conduction and hence algorithm-onset. All of these algorithms seem to violate the rule of AV conduction by allowing the AV delay for sensed ventricular events to be longer than for ventricular paced events. The result is frequently bizarre electrocardiographic (ECG) appearances that often are unique to the company's algorithm but also suggest pacemaker malfunction. This review highlights and illustrates the features of these algorithms as they appear on ECG, and discusses other situations that result in unintended ventricular pacing.

Knowing About Device Algorithms to Understand the Rhythm and Role of Managed Ventricular Pacing

A 66-year-old patient with a DR pacemaker for intermittent atrioventricular block presented with an electrocardiogram (ECG) showing some P waves non followed by QRS complexes, raising suspicion of device dysfunction. The device was equipped with a special algorithm (Managed Ventricular Pacing; Medtronic), and the observed ECG tracing was a normal consequence of the function of such algorithms. Being aware of the function of specific algorithms is essential to adequately analyze rhythms.

Cardiomyopathy induced by artificial cardiac pacing: myth or reality sustained by evidence?

Implantable cardiac pacing systems are a safe and effective treatment for symptomatic irreversible bradycardia. Under the proper indications, cardiac pacing might bring significant clinical benefit. Evidences from literature state that the action of the artificial pacing system, mainly when the ventricular lead is located at the apex of the right ventricle, produces negative effects to cardiac structure (remodeling, dilatation) and function (dissinchrony). Patients with previously compromised left ventricular function would benefit the least with conventional right ventricle apical pacing, and are exposed to the risk of developing higher incidence of morbidity and mortality for heart failure. However, after almost 6 decades of cardiac pacing, just a reduced portion of patients in general would develop these alterations. In this context, there are not completely clear some issues related to cardiac pacing and the development of this cardiomyopathy. Causality relationships among QRS widening with a left bundle branch block morphology, contractility alterations within the left ventricle, and certain substrates or clinical (previous systolic dysfunction, structural heart disease, time from implant) or electrical conditions (QRS duration, percentage of ventricular stimulation) are still subjecte of debate. This review analyses contemporary data regarding this new entity, and discusses alternatives of how to use cardiac pacing in this context, emphasizing cardiac resynchronization therapy.