Outflow Tract Pacing Research Articles

Left bundle branch area pacing compared to right ventricular outflow tract pacing: mid-term results and learning curve

Abstract Funding Acknowledgements Type of funding sources: None. Background The aim was to evaluate efficacy and feasibility of left bundle branch area pacing (LBBAP) with right ventricle outflow tract pacing(RVOP), as well as describing the learning curve. Methods Prospective single-center observational study, including 200 patients that required pacemaker implantation. Two groups: LBBAP and RVOP with 100 patients each. Our aim was to compare safety and efficacy as well as the procedure and fluoroscopy times and to describe the LBBAP-learning curve. Results Success and acute complication rate were similar in both groups(p=0.56,p=0.65). Time for ventricular lead placement was higher in LBBAP group(18 [13-28] vs 11[7-17]min, p<0.001). Fluoroscopy time was lower in LBBAP, (2.8[1.3-3.7] vs 3.1[2-5.9]min, p=0.02). Paced-QRS was narrower in LBBAP group (122.9±13.7ms vs 145.7±17.6ms, p=0.002). There were no differences related to pacing parameters. In LBBAP group, procedure time was lower in the last quartile (Q4) compared to the first quartile (12 [10.5-15] vs 32[28.5-38.5]min, p<0.001) as well as fluoroscopy time (2[1-4.6] vs 5.1[3.4-12]min, p<0.01). Procedure time was similar between LBBAP-Q4 and RVOP (12[10.5-15] vs 11[7-17]min, p=0.33). Conclusions LBBAP is as safe as RVOP and it achieved a narrower paced-QRS than RVOP. It requires a longer procedure time and a shorter fluoroscopy time, with a rapid learning curve.

Comparison of the Acute Effects of Different Pacing Sites on Cardiac Synchrony and Contraction Using Speckle-Tracking Echocardiography.

Background: Cardiac pacing in patients with bradyarrhythmia may employ variable pacing sites, which may have different effects on cardiac function. Left bundle branch pacing (LBBP) is a new physiological pacing modality, and the acute outcomes on cardiac mechanical synchrony during LBBP remain uncertain. We evaluated the acute effects of four pacing sites on cardiac synchrony and contraction using speckle-tracking echocardiography, and comparisons among four different pacing sites were rare.Methods: We enrolled 21 patients with atrioventricular block or sick sinus syndrome who each sequentially underwent acute pacing protocols, including right ventricular apical pacing (RVAP), right ventricular outflow tract pacing (RVOP), His bundle pacing (HBP), and left bundle branch pacing (LBBP). Electrocardiograms and echocardiograms were recorded at baseline and during pacing. The interventricular mechanical delay (IVMD), the standard deviation of the times to longitudinal peak strain during 17 segments (PSD), and the Yu index were used to evaluate ventricular mechanical synchrony. Layer-specific strain was computed using two-dimensional speckle tracking technique to provide in-depth details about ventricular synchrony and function.Results: Left ventricular ejection fraction (LVEF) and tricuspid annulus plane systolic excursion (TAPSE) were significantly decreased during RVAP and RVOP but were not significantly different during HBP and LBBP compared with baseline. RVAP and RVOP significantly prolonged QRS duration, whereas HBP and LBBP showed non-significant effects. IVMD and PSD were significantly increased during RVAP but were not significantly different during RVOP, HBP, or LBBP. LBBP resulted in a significant improvement in the IVMD and Yu index compared with RVAP. No significant differences in mechanical synchrony were found between HBP and LBBP.Conclusion: Among these pacing modalities, RVAP has a negative acute impact on cardiac synchrony and contraction. HBP and LBBP best preserve physiological cardiac synchrony and function.

Left bundle branch pacing: efficacy and safety compared to right ventricular outflow tract pacing

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Patients with preserved left ventricular ejection fraction (LVEF) and atrioventricular block (AVB) who are anticipated for high-burden of right ventricular (RV) pacing possess a risk to develop pacing-induced cardiomyopathy and adverse clinical outcomes. Left bundle branch pacing (LBBP) has recently emerged as a mode of conduction system pacing in the quest for physiological pacing. Purpose The aim of our study was to assess LBBP feasibility and safety compared to right ventricular outflow tract pacing (RVOTP). Methods Single centre randomized clinical trial to investigate acute success, feasibility and safety of LBBP versus RVOTP. May to October 2020. Patients with pacemaker indication and preserved LVEF were randomized 1:1 and followed up 3 months. Success was defined in LBBP group as a paced ECG < 120ms or with a 20% length reduction from the basal ECG. Results 120 patients were randomized, 60 in each group, 61% males. The mean age was 77,9 ± 9 years and third-degree AVB was the main pacing indication. The procedure was successful in 95% of the cases in both groups (p = 1). The paced QRS interval was narrower in the LBBP group compared to the RVOT group (99 ± 2 ms vs 113,6 ± 11,7 ms, p < 0,001). Lower fluoroscopy times were achieved in LBBP group (3.1 ± 2.1 min vs 4.3 ± 3.4, p = 0,035) and also longer procedure times in LBBP group (68,9 ± 36,9 min vs 44,3 ± 18,7 min, p < 0,001). No complications were achieved and no difference in ventricular lead dislocation was found between both groups (1.6% vs 1.6%)(p = 1). Conclusions LBBP is feasible, safe and provides a narrower paced QRS compared to RVOTP. LBBP required lower fluoroscopy times but longer procedure times compared to RVOTP. LBBP (n = 60) RVOTP (n = 60) p Age (mean ± SD) 76,7 ± 9 79,7 ± 8 0,067 Male gender 62 (37) 60 (36) 1 Successful procedure 95 (57) 95 (57) 1 Basal left bundle branch block 15 (9) 13 (8) Basal QRS duration (mean ± SD) 112,6 ± 29,6 109,9 ± 25,8 0,59 Pacing QRS duration (min)(mean ± SD) 99 ± 2 139,6 ± 11,7 < 0,001 Procedure time (min) (mean ± SD) 68,9 ± 36,9 44,3 ± 18,7 < 0,001 Fuoroscopy time (min)(mean ± SD) 3.1 ± 2.1 4.3 ± 3.4 0,035 R wave (mV)(mean ± SD) 9,9 ± 5,7 9,9 ± 5 0,98 Right ventricle pacing threshold (V)(mean ± SD) 0,67 ± 0,3 0,58 ± 0,24 0,08 Ventricular lead dislocation 1.6 (1) 1.6 (1) 1

How to Safely Implant a Dual-Chamber Pacemaker for Right Ventricular Outflow Tract Pacing in a Patient with Persistent Left Superior Vena Cava: A Step by Step Guide.

The implementation of advanced endovascular electrophysiological methods in patients with congenital venous anomalies (CVA) remains understudied.1 Patients with CVA have an average life expectancy. At times requiring interventional management of dysrhythmias, CVA can pose a challenge for the placement of implantable pacing devices. Persistent left superior vena cava (PLSVC) is the most common venous congenital anomaly. Herein the author discusses a safe technique of transvenous pacing lead implantation into right ventricular outflow tract (RVOT) and right atrial appendage in a 70-year-old patient with PLSVC.

Early Right Ventricular Apical Pacing-Induced Gene Expression Alterations Are Associated with Deterioration of Left Ventricular Systolic Function.

The chronic high-dose right ventricular apical (RVA) pacing may have deleterious effects on left ventricular (LV) systolic function. We hypothesized that the expression changes of genes regulating cardiomyocyte energy metabolism and contractility were associated with deterioration of LV function in patients who underwent chronic RVA pacing. Sixty patients with complete atrioventricular block and preserved ejection fraction (EF) who underwent pacemaker implantation were randomly assigned to either RVA pacing (n = 30) group or right ventricular outflow tract (RVOT) pacing (n = 30) group. The mRNA levels of OPA1 and SERCA2a were significantly lower in the RVA pacing group at 1 month's follow-up (both p < 0.001). Early changes in the expression of selected genes OPA1 and SERCA2a were associated with deterioration in global longitudinal strain (GLS) that became apparent months later (p = 0.002 and p = 0.026, resp.) The altered expressions of genes that regulate cardiomyocyte energy metabolism and contractility measured in the peripheral blood at one month following pacemaker implantation were associated with subsequent deterioration in LV dyssynchrony and function in patients with preserved LVEF, who underwent RVA pacing.

Pacing lead is more easily located at RVOT septum in patients with severe tricuspid regurgitation

Objective The optimal right ventricular (RV) pacing site in patients referred for permanent cardiac pacing remains controversial. The present study aims to evaluate at which pacing site the electrode is more easily and steadily located in patients with severe tricuspid regurgitation (TR).Methods and results We prospectively enrolled 50 patients with severe TR for permanent pacemaker implantation and randomly divided them into two groups to receive either RV apex (group A) or RV outflow tract (RVOT) pacing (group B). Time of X-ray exposure for ventricular lead deployment, incidence of intra-procedural dislodgement and post-procedural cTnT level were compared between the two groups. Lead performance and echocardiographic parameters were evaluated during follow-up. Fractional shortening (FS) of both RV body and RVOT were assessed so as to analyse the wall motion of the two RV components. As a result, RV body demonstrated a significantly higher FS than RVOT (36.7 ± 5.0% vs30.0 ± 4.6%, P< 0.01) among all TR cases. Compared with group A, less X-ray time was needed for ventricular lead implantation in group B (114.2 ± 28.9 s vs147.2 ± 55.6 s, P= 0.011) with a lower incidence of intra-procedural dislodgement (4% vs24%, P= 0.042). RVOT pacing was also associated with a lower cTnT level 6 and 24 hours after procedure (P <0.01). Lead performance and echocardiographic parameters during follow-up revealed no difference between RV apex and RVOT pacing.Conclusion In patients with severe TR, the ventricular lead is more easily and steadily located at RVOT septum than at the RV apex with shorter fluoroscopy time, lower incidence of intra-procedural dislodgement and less myocardial injury.

Functional characteristics of left ventricular synchronization via right ventricular outflow-tract pacing detected by two-dimensional strain echocardiography

BackgroundRecently, due to the detrimental effects on the ventricular function associated with right ventricular apical (RVA) pacing, right ventricular septal (RVS) pacing has become the preferred pacing method. However, the term RVS pacing refers to both right ventricular outflow-tract (RVOT) and mid-septal (RVMS) pacing, leading to a misinterpretation of the results of clinical studies. The purpose of this study, therefore, was to elucidate the functional differences of RVA, RVOT, and RVMS pacing in patients with atrioventricular block. MethodsWe compared the QRS duration, global longitudinal strain (GLS), and left ventricular (LV) synchronization parameters at the three pacing sites in 47 patients. The peak systolic strain (PSS) time delay between the earliest and latest segments among the 18 LV segments and standard deviation (SD) of the time to the PSS were also calculated for the 18 LV segments at each pacing site using two-dimensional (2D) strain echocardiography. ResultsRVMS pacing was associated with a significantly shorter QRS duration compared with RVA and RVOT pacing (154.4±21.4 vs 186.5±19.9 and 171.1±21.5ms, P<0.001). In contrast, RVOT pacing revealed a greater GLS (−14.69±4.92 vs −13.12±4.76 and −13.51±4.81%, P<0.001), shorter PSS time delay between the earliest and latest segments (236.0±87.9 vs 271.3±102.9 and 281.9±126.6%, P=0.007), and shorter SD of the time to the PSS (70.8±23.8 vs 82.7±30.8 and 81.5±33.7ms, P=0.002) compared with RVA and RVMS pacing. ConclusionsThese results suggest that the functional characteristics of RVOT pacing may be a more optimal pacing site than RVMS, regardless of the pacing QRS duration, in patients with atrioventricular conduction disorders.

Assessment of left ventricular electromechanical activation during right ventricular apical and outflow tract pacing

Abstract Background Right ventricular (RV) apical pacing, induces asynchronous ventricular contraction and impairs cardiac function. Alternative sites of pacing particularly right ventricular outflow tract (RVOT) may have a more favorable hemodynamic profile, physiological left ventricular (LV) activation and normal ventricular contraction pattern. The Aim of the study was to find out the best alternative sites to RV apex for permanent pacemaker (PM) lead fixation in the RVOT, based on the width of the QRS in the surface ECG. Patients and methods The study included 69 patients with pacemaker-dependent complete heart block; 35 with active pacemaker lead fixation in the site which achieved narrowest max. QRS duration in the RVOT (group 1) and 34 with active pacemaker lead fixation in RV apex (group 2). Results High RVOT septum was the site which achieved the narrowest QRS duration on surface ECG (117.86 ± 8.43 ms) when compared with RV apex (140.29 ± 13.14) ( p p p Conclusion High RVOT septum is the ideal site for PM lead implantation. Compared with RV apical pacing, it is associated with improvement in functional and hemodynamic parameters over medium-term follow-up.

Reversible myocardial perfusion defects in patients not suffering from obstructive epicardial coronary artery disease as assessed by coronary angiography.

In approximately 10-30% of patients presenting with angina complaints, normal or non-obstructive coronary arteries are found on angiography. In this review paper, available literature on the underlying pathophysiological substrate explaining these discrepancies is reviewed. Both histological studies as well as studies using intravascular ultrasound e.g. the PROSPECT trial, show that epicardial coronary vessel significant lumen stenosis may be delayed until a plaque occupies 40% of the internal elastic lamina area. Limited available data suggest that these angiographically undetectable plaques are associated with an abnormal vasodilation capacity of the coronary circulation and may results in reversible perfusion defects on myocardial perfusion imaging (MPI). Organic non-atherosclerotic causes of epicardial coronary artery disease such as anomalous coronary arteries that course between the aorta and pulmonary artery, myocardial bridging and coronary vasospasm may also contribute to MPI results suggesting the presence of ischemia in the presence of normal coronary arteries on coronary angiography. Additional causes of reversible perfusion defects on MPI in the presence of a normal coronary angiogram are intraventricular conduction disturbances. The existence of reversible perfusion defects in the anteroseptal region in most of the patients suffering from left bundle branch block (LBBB) on MPI following physical exercise as stressor is well documented. As the observed reduced septal uptake of both 201Tl and 99mTc-sestamibi/tetrofosmin in LBBB reflects coronary autoregulation in response to lower oxygen demands, not surprisingly, dipyridamole which uniformly exploits flow reserve, has proven more accurate for the diagnosis of coronary artery disease (CAD) in patients suffering from LBBB. Although patients with a permanent ventricular pacemaker have a similar conduction abnormality as patients presenting with a LBBB, most of the defects found on MPI imaging in this patient population (in up to 78% of patients with a normal coronary angiogram that area continuously paced) are localized in the inferoposterior (71%), apical (50%) and inferoseptal (28%) wall; coronary flow velocities in the left anterior descending (LAD) and dominant coronary artery and coronary flow reserve are also significantly lower when compared to a control group. Contrary to what is seen in LBBB patients, dipyridamole stress does not significantly reduce the incidence of abnormalities found but limits the defects to the inferior wall. Furthermore, the frequency of abnormalities found on MPI increases over time with right ventricular outflow tract pacing. Previous histologic studies have shown that microvessel disease is often accompanied by a slow-flow phenomenon reflecting decreased resting flow velocity. Thus, not surprisingly, MPI reversible abnormalities in the presence of a normal coronary angiogram have been reported in a wide variety of diseases characterized by microvessel disease such as diabetes, systemic lupus erythematosus, Behçet's disease and metabolic syndrome. In these patients, low adiponectin and high lipoprotein(a) levels are found which are known to be associated with endothelial dysfunction, atherosclerosis and coronary artery disease. Furthermore, in these patients, limited available data suggest that reversible perfusion defects on MPI confer a significantly poorer prognosis both in terms of hard event rate (MI and cardiac death) and total event rate (MI, cardiac death or late revascularization). It is thus suggested that MPI could discriminate patients with a more severe prognosis. Finally, physical training in patients with primary microvascular angina appears to be associated with reduction of myocardial perfusion abnormalities.

Electromechanical Resynchronization with High Energy Septal Pacing

Background: Standard cardiac pacing in the right ventricular apex alters electrical synchrony generating left bundle branch block that in some cases causes mechanical dyssynchrony. Pacing taking into account the anatomy (septal pacing) and with enough energy to narrow the QRS complex could have a beneficial effect, improving electrical and mechanical synchrony,and consequently myocardial function.Objective: The aim of this study was to evaluate acute electrical, mechanical and hemodynamic behavior in patients with severe intraventricular conduction disorders treated with high-energy septal pacing, and compare it with other pacing sites in the right ventricle (apex and outflow tract).Methods: Thirty patients whose average age was 65 years were continuously analyzed. They were divided into: Group I (n=15) with severe conduction disorders, complete left bundle branch block or complete right bundle branch block associated with left anterior hemiblock, all with dilated cardiomyopathy and ejection fraction (EF) <35%, and Group II (n=15) without conduction disorders and preserved EF.All patients underwent an electrophysiological study where the following parameters were evaluated in the acute phase: QRS duration in ms, time between the onset of surface QRS or spike and the most distal sites of the basal left ventricular (LV) wall, measured in the coronary sinus (R-LV), isovolumic contraction time (ICT) and ejection fraction measured by tissue Doppler echocardiography (performed off-line by an echocardiography specialist) and LV dP/dtmax assessed with an intracardiac Millar catheter (only in 18 cases). All these variables were evaluated at baseline (without pacing), with high energy septal pacing (7.5 V and 1 ms pulse width), and with right ventricular apical and outflow tract pacing. High energy pacing was used to evaluate the thresholds for QRS “narrowing”.Results: In Group I, QRS, R-LV and isovolumic contraction times improved with high energy septal pacing, but not with pacing in other sites, even with improved EF. Conversely, in Group II without conduction disorders, high energy septal pacing did not prolong QRS, R-LV or isovolumic contraction times, nor improved EF, but these parameters increased with pacing in other sites.Left ventricular dP/dtmax showed an average increase of 14% in 16 of the 18 patients evaluated in the acute phase.Conclusions: In patients with severe conduction disorders and low ejection fraction (EF), septal pacing allows electromechanical resynchronization with improved EF and dP/dtmax. In patients without conduction disturbances, this septal pacing does not modify electrical synchrony while pacing in other sites such as the right ventricular apex and outflow tract impairs it.

Pacemaker Lead Perforation during Right Ventricular Outflow Tract Pacing -Importance of Heart Rotation at Pacemaker Implantation

A 70 year-old woman underwent a dual-chamber pacemaker implantation for episodes of transient block and syncope. The transitional zone of her ECG was observed between V4 and V5, indicating clockwise rotation. An experienced physician performed the Right Ventricular Outflow Tract (RVOT) pacing using an active fixation lead without any immediate complications. For RVOT pacing, the lead was placed approximately two-thirds of the distance from the apex to the pulmonary valve in the postero-anterior view and pointing towards the septum in the left anterior oblique view. The ECG revealed a narrow QRS (120 msec) and the lead I morphology was minus-plus. Six days post-implant, a pacemaker interrogation revealed ventricular undersensing and loss of capture with high output pacing. Chest computed tomography revealed the left ventricle was displaced to the left and the left-sided angle between the interventricular septum and horizontal axis of the body was reduced to 16°. It confirmed an RV lead perforation through the RVOT, with 1 cm of the lead positioned outside the heart. We performed a surgical repair. Though ECG and x-rays showed septal pacing, we experienced an unusual case of a subacute myocardial perforation caused by an active fixation lead possibly due to heart rotation. The present case report described a patient with a subacute lead perforation and no hemodynamic instability. It is important for the general cardiologist to pay attention to heart rotation. After implantation, symptoms that can suggest a lead perforation, as major signs such as pericardial effusion are not necessarily present. A pacemaker interrogation shows lower impedance, as well as undersensing or failure to capture the involved chamber in suspicious findings.

Inadequacy of fluoroscopy and electrocardiogram in predicting septal position in RVOT pacing – Validation with cardiac computed tomography

BackgroundElectrocardiographic (ECG) and fluoroscopic criteria, which are the only available guides to achieve a true septal position during right ventricular outflow tract (RVOT) pacing, have been infrequently validated. We sought to validate these using cardiac computed tomographic angiography (CTA) to confirm lead position within the RVOT septum. MethodsForty-four patients with permanent pacemaker leads in the RVOT position underwent CTA. Lead positions in RVOT were classified as anterior, free wall, or septal location. Fluoroscopic images were obtained in 4 standard views. ResultsOnly 19 (43%) patients had lead in true septal position within the RVOT in CTA while 25 patients (57%) were found to have an anterior lead location. Mean QRS axis, QRS duration, negative QRS in lead I, and notching in inferior leads were not significantly different between the two groups. The standard fluoroscopic LAO view showed a rightward-directed lead not only in all 19 patients with septal location, but also in 14/25 patients in the anterior location (p=0.22), and thus had a sensitivity of 100% but specificity of only 16% in predicting true septal position. The posteriorly directed lead in left lateral view was more accurate in predicting true septal position with good sensitivity (73.7%) and excellent specificity (80%). ConclusionsThis study, using validation with CTA, showed that conventional ECG criteria and fluoroscopy are inaccurate in differentiating septal from anterior RVOT pacing. The fluoroscopic lateral view, as corroborated by CTA, is more reliable than the LAO view in predicting septal lead placement.

Comparison of left ventricular systolic function and mechanical dyssynchrony using equilibrium radionuclide angiography in patients with right ventricular outflow tract versus right ventricular apical pacing: A prospective single-center study

BackgroundChronic ventricular pacing is known to adversely affect left ventricular (LV) function. Studies comparing right ventricular outflow tract (RVOT) pacing with RV apical (RVA) pacing have shown heterogeneous outcomes. Our aim was to objectively assess LV function and mechanical dyssynchrony in patients with RVOT and RVA pacing using equilibrium radionuclide angiography (ERNA). MethodsFifty-one patients who underwent permanent pacemaker implantation and had normal LV function were prospectively included. Twenty-nine patients had pacemaker lead implanted in the RVOT and 22 at the RVA site. All patients underwent ERNA within 5 days post-pacemaker implantation and follow-up studies at 6 and 12 months. Standard deviation of LV mean phase angle (SD LV mPA) expressed in degrees, which was derived by Fourier first harmonic analysis of phase images, was used to quantify left intraventricular dyssynchrony. ResultsNo significant difference was observed between the two groups with respect to indication (P = .894), Type/mode (P = .985), and percentage of ventricular pacing (P = .352). Paced QRS duration was significantly longer in RVA group than RVOT group (P = .05). There was no statistically significant difference between the RVA and RVOT groups at baseline with respect to LVEF (P = .596) and SD LV mPA (P = .327). Within the RVA group, a significant decline in LVEF was observed over 12-month follow-up (from 57.3% ± 5.32% to 55.6% ± 6.25%; P = .012). In the RVOT group, the change in LVEF was not statistically significant (from 56.7% ± 4.08% to 54.3% ± 6.63%; P = .159). No significant change in SD LV mPA was observed over 12-month follow-up within the RVA group (from 10.5 ± 2.58° to 10.4 ± 3.54°; P = 1.000) as well as in the RVOT group (from 9.7 ± 3.28° to 9.4 ± 2.85°; P = .769). However, between the RVA and RVOT groups, no significant difference was observed at 12-month follow-up in terms of LVEF and dyssynchrony (LVEF P = .488; SD LV mPA P = .296). ConclusionNo significant difference was observed between RVOT and RVA groups with regard to LV function and synchrony over a 12-month follow-up. RVOT pacing offers may lead to better preservation of LV function on longer follow-up.

Characterisation and Comparison of Acute Haemodynamic, Cardiac Biochemical and Hormonal Response to Different Ventricular Pacing Sites in the Normal Heart

Acute cardiac response to right ventricular pacing is unknown. We aimed to assess the acute haemodynamic, biochemical and hormonal response to asynchronous right ventricular pacing and investigate whether there is a difference between an apical and outflow tract site. In 21 patients with normal cardiac function, haemodynamics, brain natriuretic peptide and high sensitive troponin T were measured in response to 10minutes of pacing at each site in a randomised crossover fashion and compared. Pacing both sites there were significant increases in pulmonary capillary wedge pressures (p<0.001) and QRS width (p< 0.01). In comparison to baseline, apical pacing demonstrated significant (p<0.05) increases in arterial peptide and troponin levels and venous peptide levels. Outflow tract pacing compared to baseline demonstrated significant (p<0.05) increases in arterial peptide and venous, arterial and coronary sinus troponin. There were no significant differences in responses between sites. Asynchronous right ventricular pacing demonstrated significant increases in filling pressures, cardiac hormonal and biochemical response above baseline with very short durations of pacing (10minutes). There was no difference in response between sites. These findings imply that even very short periods of right ventricular based pacing are potentially deleterious.

Optimizing paced ventricular function in patients with and without repaired congenital heart disease by contractility-guided lead implant.

This study evaluates the concept of optimizing ventricular pacing in regard to functional cardiac response. Lead implant based on physiologic variables of contractility at various sites was performed in patients with and without congenital heart disease (CHD). Since right ventricular apical pacing may adversely alter contractility and myocellular function, septal and outflow tract pacing have been advocated. However, there are few studies in the young and essentially none in those with CHD. A total of 113 consecutive patients with and without repaired CHD, aged two to 51 (median 16), some with preexisting epicardial pacemakers, underwent transvenous pacemaker implant using standard sensing/pacing indices plus measurements of pressures, QRS, and contractility responses at each of five predefined potential ventricular implant sites: apex, inflow-, low-, mid-, and infundibular/outflow-septal with each patient serving as his/her own control. Implant was at the site of best contractility with active-fixation, low-threshold steroid-eluting leads. Measured contractility indices varied up to 31% (mean 12%) between sites per patient. Septal regions (mid-, inflow-, and low-) were associated with the most optimal and right ventricular epicardial showed the worst contractility (P < 0.05) responses. Apex was optimal in some CHD patients. Threshold and sensing were comparable up to 11 years (mean 7) postimplant regardless of septal site. There is no single "sweet spot" for optimal ventricular pacing, and the best implant sites are patient and CHD variable. Current lead designs ensure chronic stability/performance regardless of site. Proactive contractility-guided pacing implant can optimize chronic paced ventricular function.

PT002 Comparison of invasive haemodynamics, Brain Natriuretic Peptide and high sensitivity Troponin T levels with right ventricular apical and right ventricular outflow tract pacing in normal hearts

Introduction: The data about the incidence of subclavian venous (SCV) obstruction or thrombosis after transvenous device implantation is limited and it is rare following immediate period after the implantation. However, when it is neccesary to substitute defected leads or improve the funcional status by making a device upgrade, the presence of obstruction or severe stenosis can make the intervention difficult, forcing to use the opposite side to implant the new device. Objectives: We aimed to assess the incidence of venous obstruction or severe stenosis and its tortuosity after a pacemaker or ICD implantation in our population. We obtained an iodinated contrast venography study just before the elective device’s replacement due to battery discharge. Methods: A contrast venography was performed in 26 patients who were candidates to elective generator change due to battery discharge. 16 p (64%) were men, the main age was 77 11 years; 13p (50%) had Chronic Heart Failure and in 18p (72%) Ischemic cardiomyopathy was diagnosed. The mean period between the first implant and device’s replacement was 9,3 3,4 years. 17p (68%) had Diabetes Mellitus, 15p (60%) were Hypercholesterolemic, 9p (36%) were smokers and 11p (44%) were had systemic arterial hypertension. Results: The initial indication to implantation the device was AuriculoVentricular block in 11p (42%), sinus node dysfunction in 8p (32%), resynchronization therapy with or without ICD in 5p (20%), and prevention of sudden death without resynchronization therapy in 1p(4%). The generator was DDD in 11p (44%), VDD in 2p (8%), VVI in 6p (24%)%, CRT in 4p (16%), and CRT-ICD in 2p (8%). The Right Ventricular lead was implanted in the outflow tract in 14p (56%) and in 11p(44%) the site was the right ventricular apex. In 100% of the patients the leads were implanted through the Left Subclavian Vein. Venous severe stenosis or obstruction was observed with venographic study in 4p (16%) and tortuosity in 2p(8%). We didn’t find any predictor of severe stenosis or obstruction of the access veins. Conclusion: Severe stenosis, obstruction or tortuosity of the access veins after a pacemaker or ICD implantation make difficult futures upgrades and leads change. The process can be facilitated by means of doing a previous venography. In our population it is unusual in an intermediate-long term period Disclosure of Interest: None Declared

COMPARATIVE STUDY BETWEEN RIGHT VENTRICULAR OUTFLOW TRACT AND RIGHT VENTRICULAR APEX PACING ON CARDIAC FUNCTION

ObjectivesTo evaluate cardiac function change in patients using the right ventricular outflow tract and right ventricular apex pacing.Methods119 patients with bradyarrhythmias in our hospital were consecutive selected, cardiac pacemaker implantation...

Response to Avi Shimony and Guy Amit: Right ventricular outflow tract pacing: the suitable technology, the accurate place, and the right patient

We really appreciate your interest in our article published in the March 2012 issue of the Europace .1 We would like to thank you for your comments and opinions on right ventricular outflow tract (RVOT) pacing.2 The right ventricular apex (RVA) has been the elective pacing site in patients with potentially life-threatening bradycardias since 1959, because it is easily accessible, readily identified, and associated with a stable position and reliable chronic pacing parameters. Nevertheless, the conventional RVA pacing may have detrimental effects on atrial fibrillation, cardiac structure, and left …

Effect of right ventricular pacing site on QRS Width

To assess the effect of various right ventricular pacing sites on QRS duration, we enrolled 50 patients (mean age, 64 ± 13 years; 36 men); 16 had bradycardia and 34 had tachycardia. The right ventricle was arbitrarily divided into 5 sections: high and low right ventricular outflow tract, mid septum, low septum, and apex. Right ventricular pacing was performed using an electrode catheter at each of the 5 sites. QRS duration was 162 ± 20 ms during high right ventricular outflow tract pacing, 143 ± 17 ms during low right ventricular outflow tract pacing, 151 ± 20 ms during mid-septal pacing, 163 ± 16 ms during low-septal pacing, and 167 ± 18 ms during apical pacing. Paced QRS duration was shorter during low right ventricular outflow tract and mid-septal pacing compared to apical pacing in 34 patients. There was a difference of 10 ms or less in the paced QRS duration between these pacing sites in the other 16 patients. QRS duration was shortest when the septum was paced in the right ventricle. However, QRS duration was similar during pacing in the septum and the apex in 32% of patients.

Right ventricular outflow pacing induces less regional wall motion abnormalities in the left ventricle compared with apical pacing

This study aimed to explore if the right ventricular outflow tract (RVOT) pacing is superior to right ventricular apical (RVA) pacing on the overall left ventricular (LV) function and regional wall motion. Sixty patients with atrio-ventricular (AV) block and normal ejection fraction undergoing dual-chamber pacemaker implantation were randomized to permanent ventricular stimulation either in the RVOT or the RVA. Left ventricular volume, ejection fraction, and LV regional wall motion were assessed by echocardiography. Right ventricular apical pacing had prolonged QRS duration, compared with RVOT pacing (154.1 ± 26.5 vs. 120.9 ± 22.3, P< 0.05). There were also significant differences in LV pre-ejection interval and interventricular mechanical delay (IVMD) at 12-month follow-up between the two groups, but none in the LV volume, left ventricular ejection fraction, and index of systolic synchrony (Ts-SD). During RVA pacing, the average peak systolic velocity (Sm) of 12 LV segments [3.5, 95% confidence interval (CI) 3.2-3.8 cm/s] had a trend of being lower compared with RVOT pacing (3.9, 95% CI 3.5-4.1 cm/s) (P= 0.09). Further analysis showed that the Sm at the inferior wall and posterior-septum wall was significantly decreased during RVA pacing compared with RVOT pacing. There were no significant differences for other LV segments. The RVOT pacing in AV block patients over 1 year may be superior to RVA pacing in terms of regional LV performance, LV global electromechanical delay, and IVMD, although intraventricular dyssynchrony and LV volumes do not differ. Larger trials with clinical endpoints are warranted to conclusively define the advantages of RVOT or RV septal pacing.