Right Ventricular Apical Pacing Research Articles

Advantageous effect of biventricular pacing on cardiac function and coronary flow: A case report

Conventional right ventricular apical (RVA) pacing may produce impairment of cardiac function as a non-physiological pacing mode even in patients with preserved left ventricular (LV) ejection fraction (EF) [1,2], and this deleterious effect might be prevented by biventricular (BiV) pacing [3–5]. Recently, it has been revealed that myocardial perfusion or coronary flow dynamics was exacerbated by RVA pacing [6,7], but it remains unknown whether these detrimental effects could be improved by BiV pacing.

Right Ventricular Outflow Tract Septal Pacing Is Superior to Right Ventricular Apical Pacing

BackgroundThe effects of right ventricular apical pacing (RVAP) and right ventricular outflow tract (RVOT) septal pacing on atrial and ventricular electrophysiology have not been thoroughly compared.Methods and ResultsTo identify a more favorable pacing strategy with fewer adverse effects, 80 patients who had complete atrioventricular block with normal cardiac function and who were treated with either RVAP (n=42) or RVOT septal pacing (n=38) were recruited after an average of 2 years of follow‐up. The data from electrocardiography and echocardiography performed before pacemaker implantation and at the end of follow‐up were collected. The patients in the RVOT septal pacing and RVAP groups showed similar demographic and clinical characteristics before pacing treatments. After a mean follow‐up of 2 years, the final maximum P‐wave duration; P‐wave dispersion; Q‐, R‐, and S‐wave complex duration; left atrial volume index; left ventricular end‐systolic diameter; ratio of transmitral early diastolic filling velocity to mitral annular early diastolic velocity; and interventricular mechanical delay in the RVOT septal pacing group were significantly less than those in the RVAP group (P<0.05). The final left ventricular ejection fraction of the RVOT septal pacing group was significantly higher than that of the RVAP group (P<0.05).ConclusionsCompared with RVAP, RVOT septal pacing has fewer adverse effects regarding atrial electrical activity and structure in patients with normal cardiac function.

Effect of pacemaker site on B-type natriuretic peptide levels and left ventricular function in a population with high prevalence of Chagas disease

Dear Editor:The right ventricular (RV) apex has long been the most commonsite of endocardial pacing, due to its anterior location and technicalease of lead placement. However previous data show that RV apicalpacing can cause or worsen mitral regurgitation, increase BNP levels[1] and may increase mortality [2,3]. Additionally, a dose-dependentrelationship, attributed to cardiac dyssynchrony [4], has been shownbetween RV apical pacing and both hospitalization for heart failureand mortality[5,6]. Thus, alternative RV sites have been evaluated[7].Accordingly,weaimedtoassesstheeffectsofRVpacingsite(api-calvs.non-apical)onfunctionalclass,leftventricular(LV)function,andserum B-type natriuretic peptide (BNP) 6 months and 1 year after leadplacement. Uniquely, our population contains a large percentage ofpatients with Chagas disease, in whom the effect of RV pacing siteis not well investigated.Between January/2011 and June/2012, 70 consecutive patientsreferredforelectiveorurgentpacemaker(PM)implantationatHospitaldas Clinicas, Belo Horizonte, Brazil, were approached for study partici-pation. Patients were excluded if they did not have an echocardiogramwithin24hofPMimplantation(n=10),orwere unable topresentforfollow-up visits (n = 4). Written informed consent was obtained fromall patients and Institutional Review Board and Ethics Committeeapproval was obtained.Baseline(b24hafterPMimplantation),6-month,and1-yearfollow-up visits included clinical evaluation, functional class determination,12-leadEKG,serumBNP(VIDAS®NTkit,Biomerieux),andtransthorac-ic echocardiogram (iE33, Philips Medical Systems, Andover, MA). Leftventricle systolic (LVSd) and diastolic (LVDd) diameters and ejectionfraction (LVEF) were recorded.Statistical analysis was performed using SPSS version 20.0 for MacOSX(SPSSInc.,Chicago,Illinois).Toevaluatethevariationofcontinuousvariables compared to baseline we used the paired Student's t-test orthe Wilcoxon paired test. Longitudinal data analysis was performedusingANOVA,assumingintervalmeasurement(fixedtimepoints:base-line, 6 and 12 months) and normally distributed errors. Multivariatelinear regression analysis was used to identify predictors of changes inLVSd at 12 months. p-Values ≤ 0.05 were considered statisticallysignificant.Fifty-six patients met inclusion criteria, with 40 in the apical pacinggroup(AP)and16inthenon-apicalpacinggroup(NAP).Baselinechar-acteristics, including age, gender distribution, percentage of patientswith Chagas disease, drug therapy, BNP, and echocardiographicparameters were similar between groups. The NAP group had ahigher proportion of New York Heart Association (NYHA) class Ipatients at study entry (44% vs. 13%, p = 0.04) (Table 1). Despite theproportion of symptomatic patients, only 13% in each group had leftbundle branch block, and none fulfilled criteria for biventricularpacing. Among NAP patients, 12 had implants in the septum, 3 in

Alterations in the expression of genes related to contractile function and hypertrophy of the left ventricle in chronically paced patients from the right ventricular apex.

Long-term right ventricular apical (RVA) pacing may lead to left ventricular (LV) remodelling and heart failure. This study assessed changes in the expression of genes regulating LV contractile function and hypertrophy, after permanent RVA pacing and investigated whether such changes proceed or even predict LV remodelling. We enrolled 52 consecutive patients (age 79.1 ± 7.7 years, 34 males) who underwent pacemaker implantation for bradycardic indications: Group A, 24 individuals with atrioventricular conduction disturbances and group B, 28 patients with sinus node disease. In group A, peripheral blood mRNA levels of gene sarcoplasmic reticulum calcium ATPase decreased at 3, 6, and 12 months' follow-up, while α-myosin heavy chain (MHC) decreased and β-MHC increased until 6 months follow-up. In this group, 25% of patients demonstrated significant LV remodelling. At 4 years, LV end-systolic diameter increased from 29.67 ± 3.39 mm at baseline to 35.38 ± 4.22 mm, LV end-diastolic diameter increased from 50 ± 4.95 to 56.71 ± 5.52 mm, and ejection fraction declined from 63.04 ± 10.22 to 52.83 ± 10.81%. Early alterations in gene expression were associated with a deterioration in LV function and geometry that became apparent months later. In group B, echocardiographic indexes and mRNA levels of the evaluated genes demonstrated no statistically significant changes. Permanent RVA pacing in patients with preserved ejection fraction is associated with alterations in the expression of genes regulating LV contractile function and hypertrophy, measured in the peripheral blood. These alterations are traceable at an early stage, before echocardiographic changes are apparent and are associated with LV remodelling that becomes evident in the long term.

Dyssynchrony, contraction efficiency and regional function with apical and non-apical RV pacing

BackgroundRecent work has shown no difference in change of LVEF between RV apical (RVA) pacing and non-RVA pacing in patients with normal LV function. We hypothesised that a more sensitive...

Diastolic function in paced children with cardiac defects: septum vs apex.

In children with structural congenital heart disease (CHD), the effects of chronic ventricular pacing on diastolic function are not well known. On the other hand, the beneficial effect of septal pacing over apical pacing is still controversial.The aim of this study was to evaluate the influence of different right ventricular (RV) pacing site on left ventricular (LV) diastolic function in children with cardiac defects.Twenty-nine pediatric patients with complete atrioventricular block (CAVB) and CHD undergoing permanent pacing were prospectively studied. Pacing sites were RV apex (n = 16) and RV septum (n = 13). Echocardiographic assessment was performed before pacemaker implantation and after it, during a mean follow‑up of 4.9 years.Compared to RV septum, transmitral E-wave was significantly affected in RV apical pacing (95.38 ± 9.19 vs 83 ± 18.75, p = 0.038). Likewise, parameters at the lateral annular tissue Doppler imaging (TDI) were significantly affected in children paced at the RV apex. The E´ wave correlated inversely with TDI lateral myocardial performance index (Tei index) (R2= 0.9849, p ≤ 0.001). RV apex pacing (Odds ratio, 0.648; confidence interval, 0.067-0.652; p = 0.003) and TDI lateral Tei index (Odds ratio, 31.21; confidence interval, 54.6-177.4; p = 0.025) predicted significantly decreased LV diastolic function.Of the two sites studied, RV septum prevents pacing-induced reduction of LV diastolic function.

Minimizing right ventricular pacing in sinus node disease: Sometimes the cure is worse than the disease.

Traditional right ventricular (RV) apical pacing has been associated with heart failure, atrial fibrillation and increased mortality. To avoid the negative consequences of RV apical pacing different strategies have been developed, among these a series of pacing algorithms designed to minimize RV pacing. These functions are particularly useful when there is not the need for continuous RV pacing: intermittent atrio-ventricular blocks and, mainly, sinus node disease. However, in order to avoid RV pacing, the operational features of these algorithms may lead to adverse (often under-appreciated) consequences in some patients. We describe a case of a patient with sinus node disease, in whom right atrial only pacing involved long atrio-ventricular delay to allow intrinsic ventricular conduction, which led to symptomatic hypotension that could be overcome only by "forcing" also right ventricular apical pacing. We subsequently discuss this case in the context of current available literature.

Right ventricular septal pacing: Safety and efficacy in a long term follow up.

To evaluate the safety and efficacy of the permanent high interventricular septal pacing in a long term follow up, as alternative to right ventricular apical pacing. We retrospectively evaluated: (1) 244 patients (74 ± 8 years; 169 men, 75 women) implanted with a single (132 pts) or dual chamber (112 pts) pacemaker (PM) with ventricular screw-in lead placed at the right ventricular high septal parahisian site (SEPTAL pacing); (2) 22 patients with permanent pacemaker and low percentage of pacing (< 20%) (NO pacing); (3) 33 patients with high percentage (> 80%) right ventricular apical pacing (RVA). All patients had a narrow spontaneous QRS (101 ± 14 ms). We evaluated New York Heart Association (NYHA) class, quality of life (QoL), 6 min walking test (6MWT) and left ventricular function (end-diastolic volume, LV-EDV; end-systolic volume, LV-ESV; ejection fraction, LV-EF) with 2D-echocardiography. Pacing parameters were stable during follow up (21 mo/patient). In SEPTAL pacing group we observed an improvement in NYHA class, QoL score and 6MWT. While LV-EDV didn't significantly increase (104 ± 40 mL vs 100 ± 37 mL; P = 0.35), LV-ESV slightly increased (55 ± 31 mL vs 49 ± 27 mL; P = 0.05) and LV-EF slightly decreased (49% ± 11% vs 53% ± 11%; P = 0.001) but never falling < 45%. In the RVA pacing control group we observed a worsening of NYHA class and an important reduction of LV-EF (from 56% ± 6% to 43% ± 9%, P < 0.0001). Right ventricular permanent high septal pacing is safe and effective in a long term follow up evaluation; it could be a good alternative to the conventional RVA pacing in order to avoid its deleterious effects.

Acute Effects of Pacing at Different Ventricular Sites on Left Ventricular Rotational Mechanics in a Porcine Model.

The purpose of this study was to examine the acute effects of pacing at different ventricular sites on hemodynamics and left ventricular (LV) rotational mechanics using speckle-tracking echocardiography (STE) in a porcine model. A prospective laboratory investigation. University research laboratory. Yorkshire pigs. In 9 pigs, after midline sternotomy, epicardial pacing was performed from the right ventricular outflow tract (RVOT), right ventricular apex (RVA), and LV free wall. Two-dimensional STE and conductance catheter-derived LV pressure-volume measurements were made to determine the impact of pacing from various sites on LV rotational parameters (twist/untwist) and hemodynamics. RVOT pacing caused the least decrease in end-systolic pressure from baseline (-9.5%), when compared with RVA (-19.1%) and LV (-23.4%). Systolic and diastolic parameters (Emax, Tau) also were different among RVOT (4.7±0.8 mmHg/mL, 32±4 ms), RVA (3.9±0.7 mmHg/mL, 37±6 ms), and LV sites (3.6±0.8 mmHg/mL, 42±7 ms). Similar to the effects of pacing on hemodynamics, RVOT pacing better preserved LV twist (11.1±1.8 v 8.6±1.7, 5.9±0.7 °) and untwisting rate (64.6±8.5 v 56.2±5.3, 48.2±8.5 °/s) when compared with RV apical pacing and LV pacing. Furthermore, prolongation of conduction from LV lateral to anteroseptal at LV base (26.5±3.8 v 13.8±3.3 ms, p<0.05) and LV midpapillary muscle level (35.6±5.6 v 14.1±2.4 ms, p<0.05) was observed with LV pacing compared with RVOT pacing. The present data showed that the LV twist/untwist and cardiac systolic and diastolic function were least affected by RVOT pacing. This finding may be explained by the proximity of this location to the native ventricular conduction system.

Haemodynamic consequences of targeted single- and dual-site right ventricular pacing in adults with congenital heart disease undergoing surgical pulmonary valve replacement.

AimsThe purpose of this study was to create an epicardial electroanatomic map of the right ventricle (RV) and then apply post-operative-targeted single- and dual-site RV temporary pacing with measurement of haemodynamic parameters. Cardiac resynchronization therapy is an established treatment for symptomatic left ventricular (LV) dysfunction. In congenital heart disease, RV dysfunction is a common cause of morbidity—little is known regarding the potential benefits of CRT in this setting.Methods and resultsSixteen adults (age = 32 ± 8 years; 6 M, 10 F) with right bundle branch block (RBBB) and repaired tetralogy of Fallot (n = 8) or corrected congenital pulmonary stenosis (n = 8) undergoing surgical pulmonary valve replacement (PVR) for pulmonary regurgitation underwent epicardial RV mapping and haemodynamic assessment of random pacing configurations including the site of latest RV activation. The pre-operative pulmonary regurgitant fraction was 49 ± 10%; mean LV end-diastolic volume (EDV) 85 ± 19 mL/min/m2 and RVEDV 183 ± 89 mL/min/m2 on cardiac magnetic resonance imaging. The mean pre-operative QRS duration is 136 ± 26 ms. The commonest site of latest activation was the RV free wall and DDD pacing here alone or combined with RV apical pacing resulted in significant increases in cardiac output (CO) vs. AAI pacing (P < 0.01 all measures). DDDRV alternative site pacing significantly improved CO by 16% vs. AAI (P = 0.018), and 8.5% vs. DDDRV apical pacing (P = 0.02).ConclusionSingle-site RV pacing targeted to the region of latest activation in patients with RBBB undergoing PVR induces acute improvements in haemodynamics and supports the concept of ‘RV CRT’. Targeted pacing in such patients has therapeutic potential both post-operatively and in the long term.

Detailed analysis of ventricular activation sequences during right ventricular apical pacing and left bundle branch block and the potential implications for cardiac resynchronization therapy.

Left bundle branch block (LBBB) leads to prolonged left ventricular (LV) total activation time (TAT) and ventricular electrical uncoupling (VEU; mean LV activation time minus mean right ventricular [RV] activation time); both have been shown to be preferential targets for cardiac resynchronization therapy (CRT). Whether right ventricular apical pacing (RVAP) produces similar ventricular activation patterns has not been well studied. The purpose of this study was to compare electrical ventricular activation patterns during RVAP and LBBB. We performed ECG mapping during sinus rhythm, RVAP, and CRT in 24 patients with LBBB. We observed differences in the electrical activation pattern with RVAP compared to LBBB. During LBBB, RV activation occurred rapidly; in contrast, RV activation was prolonged during RVAP (46 ± 21 ms vs 69 ± 17 ms, P <.001). There was no significant difference in LVTAT; however, differences in conduction pattern were observed. During LBBB, LV activation was circumferential, whereas with RVAP, LV activation proceeded from apex to base. Differences in the number, size, and orientation of lines of slow conduction also were observed. With LBBB, VEU was nearly twice as long as during RVAP (73 ± 12 ms vs 38 ± 21 ms, P <.001). CRT resulted in a greater reduction in VEU relative to LBBB activation (P <.001). RVAP produces significant differences in ventricular activation characteristics compared to LBBB. Significantly less VEU occurs with RVAP, and as a result CRT produces a smaller relative reduction in VEU. This may explain the finding that CRT appears to be more effective in patients with LBBB than in those who were upgraded because of high percentages of RV pacing.

Effect of right ventricular pacing lead site on left ventricular function in patients with high-grade atrioventricular block: results of the Protect-Pace study

Chronic right ventricle (RV) apical (RVA) pacing is standard treatment for an atrioventricular (AV) block but may be deleterious to left ventricle (LV) systolic function. Previous clinical studies of non-apical pacing have produced conflicting results. The aim of this randomized, prospective, international, multicentre trial was to compare change in LV ejection fraction (LVEF) between right ventricular apical and high septal (RVHS) pacing over a 2-year study period. We randomized 240 patients (age 74 ± 11 years, 67% male) with a high-grade AV block requiring >90% ventricular pacing and preserved baseline LVEF >50%, to receive pacing at the RVA (n = 120) or RVHS (n = 120). At 2 years, LVEF decreased in both the RVA (57 ± 9 to 55 ± 9%, P = 0.047) and the RVHS groups (56 ± 10 to 54 ± 10%, P = 0.0003). However, there was no significant difference in intra-patient change in LVEF between confirmed RVA (n = 85) and RVHS (n = 83) lead position (P = 0.43). There were no significant differences in heart failure hospitalization, mortality, the burden of atrial fibrillation, or plasma brain natriutetic peptide levels between the two groups. A significantly greater time was required to place the lead in the RVHS position (70 ± 25 vs. 56 ± 24 min, P < 0.0001) with longer fluoroscopy times (11 ± 7 vs. 5 ± 4 min, P < 0.0001). In patients with a high-grade AV block and preserved LV function requiring a high percentage of ventricular pacing, RVHS pacing does not provide a protective effect on left ventricular function over RVA pacing in the first 2 years. ClinicalTrials.gov number NCT00461734.

Long-term follow-up results of the pacing to avoid cardiac enlargement (PACE) trial.

We report the results of long-term follow-up of the Pacing to Avoid Cardiac Enlargement (PACE) trial, a prospective, double-blinded, randomized, multicentre study that confirmed the superiority of biventricular (BiV) pacing compared with right ventricular apical (RVA) pacing in prevention of LV adverse remodelling and deterioration of systolic function at 1 and 2 years. Patients with bradycardia and preserved LVEF were randomized to receive RVA (n = 88) or BiV pacing (n = 89). Co-primary endpoints were LV end-systolic volume (LVESV) and LVEF measured by echocardiography. There were 149 patients who had extended follow-up, with a mean duration of 4.8 ± 1.5 years (2.5-7.8 years). The primary endpoint analyses were performed in 146 patients (74 in the RVA group and 72 in the BiV group). In the RVA pacing group, the LVEF decreased while the LVESV increased progressively at follow-up, but remained unchanged in the BiV pacing group. The differences in LVEF between the RVA and BiV groups were -6.3, -9.2, and -10.7% at 1-year, 2-year, and long-term follow-up, respectively (all P < 0.001). The corresponding differences in LVESV were +7.4, +9.9, and +13.1 mL, respectively (all P < 0.001). The deleterious effects of RVA pacing consistently occurred in all the pre-defined subgroups. Furthermore, patients with RVA pacing had a significantly higher prevalence of heart failure hospitalization than the BiV group (23.9% vs. 14.6%, log-rank χ² = 7.55, P = 0.006). Left ventricular adverse remodelling and deterioration of systolic function continued at long-term follow-up in patients with RVA pacing; this deterioration was prevented by the use of BiV pacing. Also, heart failure hospitalization was more prevalent in the RVA pacing group.

Is right ventricular mid-septal pacing superior to apical pacing in patients with high degree atrio-ventricular block and moderately depressed left ventricular function?

We are aimed to investigate whether right ventricular mid-septal pacing (RVMSP) is superior to conventional right ventricular apical pacing (RVAP) in improving clinical functional capacity and left ventricular ejection fraction (LVEF) for patients with high-degree atrio-ventricular block and moderately depressed left ventricle (LV) function. Ninety-two patients with high-degree atrio-ventricular block and moderately reduced LVEF (ranging from 35% to 50%) were randomly allocated to RVMSP (n=45) and RVAP (n=47). New York Heart Association (NYHA) functional class, echocardiographic LVEF, and distance during a 6-min walk test (6MWT) were determined at 18 months after pacemaker implantation. Serum levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured using an enzyme-linked immunosorbent assay (ELISA) kit. Compared with baseline, NYHA functional class remained unchanged at 18 months, distance during 6MWT (485 m vs. 517 m) and LVEF (36.7% vs. 41.8%) were increased, but BNP levels were reduced (2352 pg/ml vs. 710 pg/ml) in the RVMSP group compared with those in the RVAP group, especially in patients with LVEF 35%-40% (for all comparisons, P<0.05). However, clinical function capacity and LV function measurements were not significantly changed in patients with RVAP, despite the pacing measurements being similar in both groups, such as R-wave amplitude and capture threshold. RVMSP provides a better clinical utility, compared with RVAP, in patients with high-degree atrioventricular block and moderately depressed LV function whose LVEF levels ranged from 35% to 40%.

Effect of Induced LV Dyssynchrony by Right Ventricular Apical Pacing on All‐Cause Mortality and Heart Failure Hospitalization Rates at Long‐Term Follow‐Up

Right ventricular apical (RVA) pacing may induce left ventricular (LV) dyssynchrony. The long-term prognostic implications of induction of LV dyssynchrony were retrospectively evaluated in a cohort of patients who underwent RVA pacing. A total of 169 patients (62 ± 13 years, 69% male) with high RVA pacing burden were included. Echocardiographic evaluation of LV volumes, ejection fraction, and dyssynchrony were performed before and after device implantation. LV dyssynchrony was assessed by 2-dimensional radial strain speckle tracking echocardiography. Based on the median LV dyssynchrony value after RVA pacing, the patient population was dichotomized (induced and noninduced LV dyssynchrony groups) and was followed up for the occurrence of all-cause mortality and heart failure (HF) hospitalization. Baseline mean LV ejection fraction was 51 ± 11%. Median LV dyssynchrony value was 40 ms (12-85 ms) before RVA pacing and increased to 91 ms (81-138 ms) after a median of 13 months (3-26 months) after RVA pacing. Median follow-up duration was 70 months (interquartile range 42-96 months). Patients with induced LV dyssynchrony, defined as LV dyssynchrony value superior to the median at follow-up (≥91 ms), showed higher mortality rates (5% and 27% vs. 1% and 3% at 3 and 5 years follow-up; log-rank P = 0.003) and HF hospitalization rates (18% and 24% vs. 3% and 4% at 3 and 5 years follow-up; log-rank P < 0.001) than patients with LV dyssynchrony <91 ms after RVA pacing. A multivariate model was developed to identify independent associates of a combined endpoint of all-cause mortality or HF hospitalization. Induction of LV dyssynchrony was independently associated with increased risk of combined endpoint (HR [95% CI]: 3.369 [1.732-6.553], P < 0.001). Induction of LV dyssynchrony by RVA pacing is associated with worse long-term mortality and increased HF hospitalization rates.

DIRECT HIS-BUNDLE PERMANENT PACING AS AN ALTERNATIVE TO CONVENTIONAL RIGHT VENTRICULAR APICAL PACING: A PILOT STUDY IN ZAGAZIG UNIVERSITY CARDIAC ELECTROPHYSIOLOGY LABORATORY

Aim: was to evaluate the feasibility of direct his bundle pacing (DHBP) as one of the physiological pacing approaches in our EP lab. Methods: All suitable patients admitted for permanent pacemaker implantation, between January and June 2013, were given a trial for DHBP. Using his bundle (HB) recording through a quadripolar catheter as an electrical and radiological guidance, custom shape stylet was used to direct an active fixation lead to the target position; a pacing protocol was applied to insure pure HB capture. A matching group of patients with apical right ventricular pacing (ARVP) were used as control, to assess the feasibility of DHBP technique. Results: Pure DHBP was successful in 12 out of 32 patients 38%.The DHBP procedure was costly when compared to ARVP in total procedure time (94.7±30.4 vs. 43.2±17.4 minutes), fluoroscopy time(35.2±10.9 vs. 10.1±3.6 minutes), patient x-ray exposure (34.1±7.8 vs. 11.9±4.9 Gy Cm2)and acute pacing threshold (2.1±0.6 vs.0.6±0.4 V). But in the other hand it was better in paced QRS width (76.8±14.8 vs. 193.9±35.8 ms.), patients’ exercise capacity as percentage of achieved METS from Max METS for age (75.5±8.7 vs.54.9±8.7%). the DHBP procedure time was progressively shorter indicating a steep learning curve. Conclusion: Although DHBP has many technical difficulties, it can be achieved with a reasonable coast in our EP lab with a demonstrable benefit, and a steep learning curve. Keywords: direct his bundle pacing, apical right ventricular pacing, physiological pacing, pacemaker, paced QRS duration, and active fixation lead.

Impact of right-ventricular apical pacing on the optimal left-ventricular lead positions measured by phase analysis of SPECT myocardial perfusion imaging

The use of SPECT phase analysis to optimize left-ventricular (LV) lead positions for cardiac resynchronization therapy (CRT) was performed at baseline, but CRT works as simultaneous right ventricular (RV) and LV pacing. The aim of this study was to assess the impact of RV apical (RVA) pacing on optimal LV lead positions measured by SPECT phase analysis. This study prospectively enrolled 46 patients. Two SPECT myocardial perfusion scans were acquired under sinus rhythm with complete left bundle branch block and RVA pacing, respectively, following a single injection of (99m)Tc-sestamibi. LV dyssynchrony parameters and optimal LV lead positions were measured by the phase analysis technique and then compared between the two scans. The LV dyssynchrony parameters were significantly larger with RVA pacing than with sinus rhythm (p ~0.01). In 39 of the 46 patients, the optimal LV lead positions were the same between RVA pacing and sinus rhythm (kappa = 0.861). In 6 of the remaining 7 patients, the optimal LV lead positions were along the same radial direction, but RVA pacing shifted the optimal LV lead positions toward the base. The optimal LV lead positions measured by SPECT phase analysis were consistent, no matter whether the SPECT images were acquired under sinus rhythm or RVA pacing. In some patients, RVA pacing shifted the optimal LV lead positions toward the base. This study supports the use of baseline SPECT myocardial perfusion imaging to optimize LV lead positions to increase CRT efficacy.

Takotsubo cardiomyopathy in the presence of right ventricular apical pacing: A case report

In Takotsubo cardiomyopathy (TCM), ST-segment elevation, T-wave inversion, and QTc prolongation are the most common electrocardiography (ECG) findings during acute and subacute periods. Right ventricular apical (RVA) pacing produces a left ventricular electrical activation sequence resembling a left bundle-branch block, and the ST–T segment changes are usually discordant from the QRS complex. Several cases have reported that abnormal ECG manifestations in TCM could be detected even in patients with a paced ventricular rhythm. However, ECG manifestations in TCM have not been well characterized in patients with RVA pacing. Here, we report a case of a 76-year-old woman with RVA pacing who was diagnosed with TCM after she experienced acute bronchitis. To the best of our knowledge, this is a rare case, showing that significant QTc prolongation and concordant T-wave inversions during full RVA pacing were longer and deeper when compared with ECG findings in past reports. The ECG findings eventually improved with a similar course as those in TCM patients without RVA pacing.

Right ventricular apical pacing–induced left ventricular dyssynchrony is associated with a subsequent decline in ejection fraction

In patients with normal left ventricular (LV) ejection fraction (EF), the interposition of chronic, high-dose right ventricular apical (RVA) pacing may produce late EF decline. To test the hypothesis that LV dyssynchrony, defined echocardiographically and apparent early after interposition of pacing, would be greater in patients who subsequently demonstrated EF decline. Ninety-one patients with normal prepacing EF who underwent atrioventricular node ablation and subsequent high-dose RVA pacing were studied. Transthoracic echocardiograms were performed early (median 4 months) and late (median 28 months) after interposition of pacing, with a significant decline in EF between these studies defined as ≥5%. Speckle-tracking longitudinal strain analysis of the early echocardiogram was performed to quantify dyssynchrony. In addition to standard dyssynchrony indices, a novel index of apex-to-base mechanical propagation delay (MPD) was used. Multivariable analysis determined that MPD of the septum correlated with a significant decline in EF, independent of all other dyssynchrony, clinical, or pacing variables. A septal MPD value exceeding 50 ms was associated with EF decline at 81% sensitivity and 88% specificity. Dyssynchrony, in particular septal MPD, measured early after interposition of high-dose RVA pacing predicted a significant late decline in EF in patients who had normal prepacing EF.

Validation of Conventional Fluoroscopic and ECG Criteria for Right Ventricular Pacemaker Lead Position Using Cardiac Computed Tomography

It is hypothesized that pacing the right ventricular (RV) septum is associated with less deleterious outcomes than RV apical pacing. Our aim was to validate fluoroscopic and electrocardiography (ECG) criteria for describing pacemaker and implantable cardioverter defibrillator RV "septal" lead position against the proposed gold standard: cardiac computed tomography (CT). Using the conventional fluoroscopic criteria, we intended to place RV nonapical leads on the interventricular septum. Lead positions were later retrospectively analyzed with CT and correlated with ECGs and fluoroscopic projections: posterior-anterior, 40° left anterior oblique (LAO), 40° right anterior oblique (RAO), and left lateral. Only 21% (nine of 35) of presumed "septal" RV nonapical leads using the conventional fluoroscopic criteria were on the true septum. A schema developed to define septal position in the RAO fluoroscopic view had high agreement with CT images. ECG criteria had only fair to moderate agreement with CT. The paced QRS duration was significantly longer (P < 0.001) with RV apical pacing (176 ± 10.7 ms), compared to RV nonapical pacing (144.5 ± 14.3 ms). Using the conventional fluoroscopic criteria, only a minority of RV leads were implanted on the true RV septum. Instead, aiming for the middle of the cardiac silhouette in the RAO fluoroscopic view, confirming rightward orientation in the LAO view, and having a paced QRS duration <140 ms may allow the implanting cardiologist a simple, more accurate method to achieve true RV septal lead positioning.