Permanent Left Bundle Branch Block Research Articles

Conduction disorders after transcatheter aortic valve implantation: association with long-term outcome

Abstract Background As the indications for Transcatheter Aortic Valve Implantation (TAVI) are expanding, the long term consequences of its potential complications, such as the development of new left bundle branch block (LBBB) or the need for permanent pacemaker (PPM) implantation, are of increasing clinical importance. Studies on the prognostic impact of conduction disorders after TAVI showed conflicting results, and data after the first year are limited. Purpose To examine the progression of significant conduction abnormalities (CA) within the first year after TAVI, and investigate the long-term outcome of PPM implantation and permanent LBBB beyond the first year. Methods Patients who underwent TAVI between 2007-2019 and who had at least 1 year follow-up were included, and divided into 3 groups: 1)PPM implantation within the first year, 2)development of LBBB persisting until 1 year (permanent LBBB), and 3)no CA. Twelve-lead electrocardiograms (ECG) were collected at baseline, post-TAVI, and at 1 year. The primary end-point was all-cause mortality. Results Among 794 patients, 502 who underwent TAVI without baseline CA were divided into those with PPM(n=89), permanent LBBB(n=56), and no CA(n=357). Baseline clinical characteristics did not significantly differ, except for the self-expanding valve, which was more common among the PPM group (40% vs 25% in LBBB and 15% in no CA, p<0.001). Baseline echocardiographic parameters were also comparable. The PPM group showed more frequent first degree AV block and right bundle branch block, as well as longer PR and QRS intervals, on pre-TAVI ECG. Immediately post TAVI, 32% of patients developed new LBBB, but only 19% persisted until discharge, and 11% at 1 year (Figure 1). Meanwhile, 18% needed a PPM within the first year, with a median time of 4 days. At 1-year follow up, overall improvement in NYHA class was observed but significantly more patients remained in NYHA class III-IV among the LBBB group (11% vs 6% in PPM and 3% in no CA, p=0.039). At 1 year, echocardiographic parameters showed significant differences, with lower left ventricular ejection fraction and global longitudinal strain (GLS) in the PPM and LBBB group compared to the no CA group (55±9% and 15±4% vs. 54±11% and 15±4% vs. 58±9% and 17±4% respectively, p<0.001). Beyond 1 year, survival analysis showed a significant difference in all-cause mortality (2= 10.168, p=0.006) between PPM and no CA group (p=0.001, Figure 2) during a median follow-up of 49 months [IQR 34-74 months]. Multivariable Cox regression showed that PPM implantation (HR 1.654, p=0.011), baseline EuroSCORE II (HR 1.072, p=0.002), NYHA III-IV at 1 year (HR 4.432, p=<0.001) and GLS at 1 year (HR 0.950, p=0.027) were independently associated with outcomes. Conclusion Post-TAVI conduction disorders are dynamic until 1 year follow-up and patients who needed a PPM implantation showed worse long term outcomes. Therefore, adequate follow-up after TAVI is of paramount importance.Progression of LBBB and PPM after TAVRKaplan Meier Survival Analysis

Relationship between left ventricular mechanical dyssynchrony with cardiac resynchronization therapy response in chronic heart failure patients with left bundle branch block

Aim. To investigate the relationship between left ventricular (LV) mechanical dyssynchrony with cardiac resynchronization therapy (CRT) response in chronic heart failure (CHF) pts with left bundle branch block.Methods. Forty-nine pts (male - 34 [69.4%], average age 58.3±11.4 years) with sinus rhythm, permanent left bundle branch block with QRS duration ≥150 ms and New York Heart Association (NYHA) II-III functional class of CHF were included in the study. In addition to full examination, myocardial perfusion scintigraphy (MPS) and gated blood pool single-photon emission computed tomography (gBPS) were performed before and 6 months after CRT devices with cardioverter-defibrillator function implantation. Pts were considered as responders to CRT if they fulfilled after 6-month follow-up the following combined criteria: NYHA FC improvement ≥1 class + LV end systolic volume decrease >15% or NYHA FC improvement ≥1 class + LV ejection fraction improvement >5%.Results. The 1st and 2nd groups included 35 (71.4%) and 14 (28.6%) pts with and without response to CRT respectively. Groups were comparable in terms of pre-CRT implantation clinical and instrumental parameters, except for MPS and gBPS parameters. The multivariate logistic regression had shown that only ∆interventricular dyssynchrony (adjusted odds ratio [OR] 1,0349; 95% confidence interval [CI] 1.0075-1,0631; р=0.01) and phase standard deviation of the anterior LV wall (OR 1.0669; 95% CI 1.0118-1.1251; p=0.01) were independently related with CRT response. An increase in the prognostic coefficient, calculated using the ∆interventricular dyssynchrony and phase standard deviation of the anterior LV wall, more than 0.67 was a predictor of CRT response (area under the curve 0.918; sensitivity 85.71; specificity 85.71; p <0.001).Conclusion. The mechanical dyssynchrony assessed by MPS and gBPS is associated with CRT response. According to our predictive model, an increase in prognostic coefficient more than 0.67 is a predictor of CRT response.

Ambulatory Smartwatch ECG Monitoring among Patients Undergoing Transcatheter Aortic Valve Replacement Early after Discharge: An Observational Study.

As an emerging arrhythmia monitor, ambulatory smartwatch electrocardiogram (ECG) provides an option for home-based monitoring of delayed new-onset arrhythmic events after transcatheter aortic valve replacement (TAVR). We aimed to validate the diagnostic efficacy of a consumer smartwatch ECG in TAVR recipients, while further explore the occurrence rate of both tachy- and brady-arrhythmia for 30 days after discharge to support risk management. Consecutive TAVR recipients from February 26th, 2021 to December 13th, 2021 were enrolled prospectively, receiving simultaneous 24-hour Holter and 12-lead ECG compared with smartwatch ECG during hospitalization and daily smartwatch ECG collection for 30 days after discharge. Among 110 patients, the efficacy of smartwatch ECG presented sensitivity and specificity in diagnosing atrial fibrillation (AF) as 1.00 and 0.97, left bundle branch block (LBBB) as 0.61 and 0.88, and right bundle branch block (RBBB) as 0.60 and 0.97, respectively, compared with 24-hour Holter; presented sensitivity and specificity in diagnosing AF as 0.88 and 1.00, LBBB as 0.90 and 0.96, and RBBB as 0.83 and 0.94, respectively, compared with 12-lead ECG. At 30-day follow-up, new-onset arrhythmia included new-onset severe conduction disturbance (SCD) (23.6%), new-onset AF (21.8%), new-onset permanent LBBB (14.5%) and new-onset permanent RBBB (0.9%); 69.2% (36/52) of early new-onset LBBB recovered at 30-day follow-up. The diagnostic efficacy of consumer smartwatch ECG in arrhythmic events among TAVR population was acceptable, which provided a recommendable option for home-based management. "Continuously ambulatory rhythm monitoring and predictors of electrocardio-related adverse events in 30 days after transcatheter aortic valve replacement"; Identifier: ChiCTR2000041244; http://www.chictr.org.cn/showproj.aspx?proj=66324.

Outcomes in patients with electrocardiographic left ventricular dyssynchrony following transcatheter aortic valve replacement

Left bundle branch block (LBBB) and atrioventricular (AV) conduction abnormalities requiring permanent pacemaker (PPM) implantation occur frequently following transcatheter aortic valve replacement (TAVR). The resultant left ventricular (LV) dyssynchrony may be associated with adverse clinical events. The purpose of this study was to assess the adverse outcomes associated with LV dyssynchrony due to high-burden right ventricular (RV) pacing or permanent LBBB following TAVR in patients with preserved left ventricular ejection fraction (LVEF). Consecutive TAVR patients at the University of Michigan from January 2012 to June 2017 were included. Pre-existing cardiac implantable electronic device, previous LBBB, LVEF <50%, or follow-up period <1 year were excluded. The primary outcome was all-cause mortality. Secondary outcomes included cardiomyopathy (defined as LVEF ≤45%), a composite endpoint of cardiomyopathy or all-cause mortality, and the change in LVEF at 1-year follow-up. A total of 362 patients were analyzed (mean age 77 years). LV dyssynchrony group (n = 91 [25.1%]) included 56 permanent LBBB patients, 12 permanent LBBB patients with PPM, and 23 non-LBBB patients with PPM and high-burden RV pacing. Remaining patients served as control (n = 271 [74.9%]). After adjusted analysis, LV dyssynchrony had significantly higher all-cause mortality (adjusted hazard ratio [HR] 2.16; 95% confidence interval [CI] 1.07-4.37) and cardiomyopathy (adjusted HR 14.80; 95% CI 6.31-14.69). The LV dyssynchrony group had mean LVEF decline of 10.5% ± 10.2% compared to a small increase (0.5% ± 7.7%) in control. Among TAVR patients with preserved LVEF and normal AV conduction, development of postprocedural LV dyssynchrony secondary to high-burden RV pacing or permanent LBBB was associated with significantly higher risk of death and cardiomyopathy at 1-year follow-up.

Outcome of transcatheter aortic valve replacement in patients over 85years of age versus patients aged85 and younger.

IntroductionThe Dutch general population is aging rapidly. Many of these patient are fit and eligible for TAVR. However, studies on outcome in older versus younger patients are scant.Material and methodsA single-centre retrospective study comparing patients older and younger than age 85 on outcome.Results190 patients underwent TAVR: 136 were aged 85 or younger (U85), 54 were older than 85 (O85). The U85 group had more men (U85: 71 [52.2%] vs O85: 19 [35.2%]; p = 0.034), a higher incidence of diabetes (U85: 36 [26.5%] vs O85: 3 [5.6%]; p = 0.001) and atrial fibrillation (U85: 35 [25.7%] vs O85: 5 [9.3%]; p = 0.03) and a higher body mass index (U85: 27.5 [± 5.24] vs O85: 26 [± 3.78]; p = 0.027). In the O85 group there was a lower estimated glomerular filtration rate (O85: 50.28 [± 15.32] ml/min vs U85: 65.25 [± 29.97] ml/min; p = 0.012). There was no difference in 30-day mortality (U85: 6 [4.4%] vs O85: 3 [5.6%]) and 1‑year mortality (U85 9 [6.6%] vs O85 3 [5.6%]) (p = 0.521). There was an equal amount of new onset permanent left bundle branch block (U85: 38 [27.9%] vs O85: 14 [25.9%]; p = 0.896) and permanent pacemaker implantation (U85: 28 [20.6%] vs O85: 28 [20.6%]; p = 0.748). There was no difference in bleeding events (p = 0.469), vascular complications (p = 0.195) or moderate/severe regurgitation (p = 0.972). The U85 group had a slightly longer admission duration (U85 6.29 [± 5.289] days vs O85 5.98 [± 3.328] days (p = 0.037)).ConclusionTAVR in patients over 85 years of age has excellent outcome, comparable to those aged 85 and younger.

Influence of deep implantation on conduction disturbances after transcatheter aortic valve implantation

HintergrundReizleitungsstörungen sind häufige Komplikationen der Transkatheter-Aortenklappenimplantation (TAVI). Ein Einflussfaktor ist die bisher nicht standardisiert bestimmte Implantationstiefe.FragestellungGibt es Unterschiede zwischen den anatomischen Regionen bei tiefer Implantation hinsichtlich neuer Reizleitungsstörungen und Überleben?Material und MethodenRetrospektive Kohortenanalyse, 420 Patienten mit transfemoraler TAVI mit Klappenprothesen der neuen Generation, davon 352 Patienten ohne vorbestehenden Schrittmacher für Analysen zur neuen Schrittmacherimplantation. Auswertung der fluoroskopisch gemessenen Implantationstiefen an der non- (NCC) und der links-koronaren Tasche (LCC) sowie der aus Patientenakten ersichtlichen Verläufe. Die tiefe Implantation definierte sich als tiefes Quartil der Implantationstiefe der jeweiligen Prothese. Das Überleben ergab sich aus einem 2‑jährigen Follow-up.Ergebnisse und DiskussionDie tiefe Implantation war nur am NCC mit erhöhter Schrittmacherimplantationsrate assoziiert (p = 0,013), am LCC mit dem häufigeren Auftreten eines permanenten Linksschenkelblocks (p = 0,014). Neue oder vorbestehende Schrittmacherimplantationen hatten keinen Einfluss auf das 2‑jährige Überleben. Eine tiefe Implantation war nicht mit einer schlechteren Überlebensprognose assoziiert. Die Implantationstiefe könnte bezüglich der Bedeutung für neue Schrittmacherimplantationen standardisiert am NCC gemessen werden. In der Eingriffsplanung könnte eine Abschätzung der Implantationstiefe am NCC oder LCC relevant für den Verlauf nach TAVI sein. Die Schrittmacherimplantation kann wie auch die tiefe Implantation am LCC oder NCC, bei Abwesenheit von mittel- bis hochgradigen paravalvulären Leckagen, als prognostisch sicher gewertet werden.

A case of catecholaminergic polymorphic ventricular tachycardia diagnosed as having long QT syndrome 25 years ago

The aim of this study is to describe electrocardiographic changes and conduction abnormalities in patients undergoing transcatheter aortic valve implantation (TAVI).76 patients who underwent TAVI using Edwards Sapien 3 prosthesis were included, comparing electrocardiographic registries at admission, post-procedure and before discharge.Patients after TAVI presented a longer PR interval, a wider QRS, and a longer corrected QT, with a left deviation of QRS axis and T waves; reversible changes that tended to correct in the following days after TAVI. Complete atrioventricular block incidence was 2.9%. New-onset left bundle branch block (LBBB) incidence was 39%, although solved in almost half of patients before discharge.TAVI was associated with different reversible electrocardiographic changes that suggest a transient impact on the conduction system. One of every five patients presented permanent LBBB after valve implant.

Role of Late Sodium Current in Experimental Torsade de Pointes

The aim of this study is to describe electrocardiographic changes and conduction abnormalities in patients undergoing transcatheter aortic valve implantation (TAVI).76 patients who underwent TAVI using Edwards Sapien 3 prosthesis were included, comparing electrocardiographic registries at admission, post-procedure and before discharge.Patients after TAVI presented a longer PR interval, a wider QRS, and a longer corrected QT, with a left deviation of QRS axis and T waves; reversible changes that tended to correct in the following days after TAVI. Complete atrioventricular block incidence was 2.9%. New-onset left bundle branch block (LBBB) incidence was 39%, although solved in almost half of patients before discharge.TAVI was associated with different reversible electrocardiographic changes that suggest a transient impact on the conduction system. One of every five patients presented permanent LBBB after valve implant.

The magic of Lidocaine load in extreme Long QT with 2:1 functional AV block

The aim of this study is to describe electrocardiographic changes and conduction abnormalities in patients undergoing transcatheter aortic valve implantation (TAVI).76 patients who underwent TAVI using Edwards Sapien 3 prosthesis were included, comparing electrocardiographic registries at admission, post-procedure and before discharge.Patients after TAVI presented a longer PR interval, a wider QRS, and a longer corrected QT, with a left deviation of QRS axis and T waves; reversible changes that tended to correct in the following days after TAVI. Complete atrioventricular block incidence was 2.9%. New-onset left bundle branch block (LBBB) incidence was 39%, although solved in almost half of patients before discharge.TAVI was associated with different reversible electrocardiographic changes that suggest a transient impact on the conduction system. One of every five patients presented permanent LBBB after valve implant.

A Difference between the Depolarization Time and QRS Duration in Heart Failure Patients with LBBB: A Simulation Study

The aim of this study is to describe electrocardiographic changes and conduction abnormalities in patients undergoing transcatheter aortic valve implantation (TAVI).76 patients who underwent TAVI using Edwards Sapien 3 prosthesis were included, comparing electrocardiographic registries at admission, post-procedure and before discharge.Patients after TAVI presented a longer PR interval, a wider QRS, and a longer corrected QT, with a left deviation of QRS axis and T waves; reversible changes that tended to correct in the following days after TAVI. Complete atrioventricular block incidence was 2.9%. New-onset left bundle branch block (LBBB) incidence was 39%, although solved in almost half of patients before discharge.TAVI was associated with different reversible electrocardiographic changes that suggest a transient impact on the conduction system. One of every five patients presented permanent LBBB after valve implant.

Left Bundle Branch Block after Transcatheter Aortic Valve Implantation with Edwards Sapien 3 Valve: Influence of the Valve Depth Implantation.

The aim of this study is to determine the relation between the valve depth implantation and the new-onset left bundle branch block (LBBB) in patients treated with transcatheter aortic valve implantation (TAVI) using Edwards Sapien 3 (S3) prosthesis. LBBB is the most common conduction disturbance after TAVI. The S3 has been associated with a higher incidence of LBBB. A deep valve implant could be related to new-onset LBBB with S3. Seventy-six consecutive patients treated with transfemoral TAVI with S3 were included. Electrocardiogram (ECG) registries were recorded at baseline, after the procedure, and before discharge. Valve depth implantation was determined in 40 patients by off-line analysis of the two/three-dimensional transeophageal echocardiogram (TEE) images, with measure of the valve stent percentage under the aortic annulus. Previous and new conduction anomalies were documented; and patient, anatomic and procedural characteristics were retrospectively analyzed. Complete atrioventricular block (AVB) incidence was 2.9%. LBBB after TAVI appeared in 39% of patients, being transient in almost half of the cases (permanent LBBB rate 20%). Patients with new-onset LBBB after TAVI were older, with a higher STS Score and a wider basal QRS. A deep valve position was associated with new-onset LBBB, with a ROC curve establishing a cut-off point of 34% of depth implant as risk factor for new-onset LBBB (sensitivity and specificity 0.8). In transfemoral TAVI with S3 prosthesis, a higher valve implantation (<34% of valve stent introduced into the ventricle) may minimize the new-onset LBBB, especially in old and high-risk patients with a wide basal QRS.

Evaluation of the predictive value of Gensini score on determination of severity of coronary artery disease in cases with left bundle branch block

Abstract Left bundle branch block (LBBB) is one of the features which predicts severe organic heart disease. In this study, we aimed to examine the predictive role of Gensini score as marker of severity of coronary artery disease (CAD) in patients with LBBB and its relationship with other CAD risk factors and complications. We have included patients who referred to our center for selective coronary angiography with transient and or permanent LBBB on their surface electrocardiography (ECG). Cases with pacemaker rhythm and known non-CAD related causes of LBBB pattern on surface ECG were excluded from this study. Demographic variables and clinical features were studied. To determine severity of CAD, Gensini score was measured. The relationship between presence of CAD and deteriorated ejection fraction has been demonstrated by previous works, but we found no association between severity of CAD and degree of ejection fraction deterioration. This might imply to the role of non-CAD factors toward reduction of ejection fraction. In cases with hypertension in the setting of LBBB, higher Gensini scores were seen regardless of ventricular ejection fraction. Thus, earlier screening for possible CAD in cases with LBBB and hypertension seems rational. Keywords: Left bundle branch block Electrocardiography Severity of coronary artery disease Gensini score

Electrocardiographic changes and conduction disturbances after transfemoral aortic valve implantation with Edwards Sapien 3 prosthesis

ObjectivesThe aim of this study is to describe electrocardiographic changes and conduction abnormalities in patients undergoing transcatheter aortic valve implantation (TAVI). Methods76 patients who underwent TAVI using Edwards Sapien 3 prosthesis were included, comparing electrocardiographic registries at admission, post-procedure and before discharge. ResultsPatients after TAVI presented a longer PR interval, a wider QRS, and a longer corrected QT, with a left deviation of QRS axis and T waves; reversible changes that tended to correct in the following days after TAVI. Complete atrioventricular block incidence was 2.9%. New-onset left bundle branch block (LBBB) incidence was 39%, although solved in almost half of patients before discharge. ConclusionsTAVI was associated with different reversible electrocardiographic changes that suggest a transient impact on the conduction system. One of every five patients presented permanent LBBB after valve implant.

Cardiac Pacing and Transcatheter Aortic Valve Implantation (TAVI): A Literature Update

Aortic valve replacement is a routine procedure with acceptable risk. In some cases, mortality is high, contraindicating the procedure. The minimally invasive transcatheter aortic valve implantation seems to be an alternative, reducing morbidity and mortality. In this procedure, a bioprosthetic valve is introduced through a catheter and fixed within the injured native aortic valve. Even though the technique is considered comparatively safe, the risks of complications exist and they that have been established by individuals after the technique, for example new-onset permanent left bundle branch block (LBBB) and the need for permanent cardiac pacing implantation. A systematic review of literature of PUBMED was carried out using “10 years” and “free full texts” as filters, containing the terms “TAVI,” “pacing,” and “complications,” finding a total of eight articles. Other databases, such as SCIELO, Google Scholar and MEDLINE were used to give background, consistency and profundity to the text. The implantation of aortic valve prosthesis per catheter seems to be a valid modality for high–surgical risk patients with aortic stenosis. The results of this series of patients suggest that the need for a definitive pacemaker after endovascular treatment is not inexorable and is not easily predicted by the risk factors described so far.

Transthoracic Doppler Echocardiographic Coronary Flow Imaging in Identification of Left Anterior Descending Coronary Artery Stenosis in Patients with Left Bundle Branch Block

Conventional noninvasive methods have well-known limitations for the detection of coronary artery disease (CAD) in patients with left bundle branch block (LBBB). However, advancements in Doppler echocardiography permit transthoracic imaging of coronary flow velocities (CFV) and measurement of coronary flow reserve (CFR). Our aim was to evaluate the diagnostic value of transthoracic CFR measurements for detection of significant left anterior descending (LAD) stenosis in patients with LBBB and compare it to that of myocardial perfusion scintigraphy (MPS). Simultaneous transthoracic CFR measurements and MPS were analyzed in 44 consecutive patients with suspected CAD and permanent LBBB. Typical diastolic predominant phasic CFV Doppler spectra of distal LAD were obtained at rest and during a two-step (0.56-0.84 mg/kg) dipyridamole infusion protocol. CFR was defined as the ratio of peak hyperemic velocities to the baseline values. A reversible perfusion defect at LAD territory was accepted as a positive scintigraphy finding for significant LAD stenosis. A coronary angiography was performed within 5 days of the CFR studies. The hyperemic diastolic peak velocity (44 +/- 9 cm/sec vs 62 +/- 2 cm/sec; P=0.01) and diastolic CFR (1.38 +/- 0.17 vs 1.93 +/- 0.3; P=0.001) were significantly lower in patients with LAD stenosis compared to those without LAD stenosis. The diastolic CFR values of <1.6 yielded a sensitivity of 100% and a specificity of 94% in the identification of significant LAD stenosis. In comparison, MPS detected LAD stenosis with a sensitivity of 100% and a specificity of 29%. CFR measurement by transthoracic Doppler echocardiography is an accurate method that may improve noninvasive identification of LAD stenosis in patients with LBBB.

Thallium-201 myocardial SPECT in left bundle branch block: Diagnosis of myocardial ischemia with a disease-specific reference database

The aim of this study was to assess the value of a myocardial perfusion single photon emission computed tomography (SPECT) reference file for patients with left bundle branch block (LBBB). Tl-201 stress-redistribution myocardial perfusion SPECT studies of patients with complete, permanent LBBB were reviewed retrospectively. To develop a reference database, 18 patients with a low likelihood of coronary artery disease (CAD) were selected. Left ventricular regional average and standard deviation (SD) values of the reference file images were calculated. The diagnostic performance was tested on perfusion images of 49 patients with LBBB, undergoing both scintigraphic and coronary angiographic evaluation, and was compared with a commercial quantitative analysis system using a general reference database. The LBBB reference file performed significantly better in detecting epicardial CAD than did the general reference database (receiver operating characteristic area under the curve 0.835 +/- 0.06 vs 0.580 +/- 0.08, p < .01). Disease localization also was improved significantly in the territory of the left anterior descending and of the right coronary arteries. The use of a reference file of patients with LBBB and a low likelihood of CAD aids the detection and the localization of myocardial ischemia on Tl-201 myocardial SPECT images of this patient group.

The Deleterious Consequences of Right Ventricular Apical Pacing: Time to Seek Alternate Site Pacing

The purpose of this article is to critically review the data accumulated to date from studies evaluating the hemodynamic and clinical effects of right ventricular apical pacing during conventional permanent cardiac pacing. The data from studies comparing the effects of right ventricular apical pacing and alternate site ventricular pacing are also reviewed. We conducted a MEDLINE and journal search of English-language reports published in the last decade and searched relevant papers. Although intraventricular conduction delay in the form of left bundle branch block (LBBB) has traditionally been viewed as an electrophysiologic abnormality, it has now become abundantly clear that it has profound hemodynamic effects due to ventricular dyssynchrony, especially in patients with heart failure. These deleterious effects can be significantly ameliorated by cardiac resynchronization therapy effected by biventricular or left ventricular pacing. However, not only is spontaneous LBBB harmful, but the iatrogenic variety produced by right ventricular apical pacing in patients with permanent pacemakers may be equally deleterious. In this review new evidence from recent studies is presented, which strongly suggests a harmful effect of our long-standing practice of producing an iatrogenic LBBB by conventional right ventricular apical pacing in patients receiving permanent pacemakers. This emerging strong new evidence about the adverse hemodynamic and clinical effects of right ventricular apical pacing would dictate a reassessment of our traditional approach to permanent cardiac pacing and direct our attention to alternate sites of pacing, such as the left ventricle and/or the right ventricular outflow tract or septum, if not for all patients, at least for those with left ventricular dysfunction. Indeed, current convincing data on alternate site ventricular pacing are encouraging and this approach should be actively pursued and further investigated in future studies. Not only is spontaneous permanent LBBB harmful to our patients, but the iatrogenic variety produced by right ventricular apical pacing during conventional permanent pacing may also be deleterious to some patients. The compelling evidence presented herein cannot be ignored; it may dictate a change of attitude toward right ventricular apical pacing directing our attention to alternate sites of ventricular pacing and avoidance of the right ventricular apex.

739 Myocardial contrast echocardiography with adenosine as a tool for the risk stratification in patients with coronary artery disease and permanent left bundle branch block

739 Myocardial contrast echocardiography with adenosine as a tool for the risk stratification in patients with coronary artery disease and permanent left bundle branch block

1.32 Exercise and dipyridamole myocardial perfusion SPELT with technetium compounds in patients with permanent left bundle branch block

1.32 Exercise and dipyridamole myocardial perfusion SPELT with technetium compounds in patients with permanent left bundle branch block

Transcatheter electrical shock ablation of ventricular tachycardia

Transcatheter shock ablation of ventricular tachycardia was attempted in seven patients who had drug-resistant ventricular tachycardia and in one patient in whom ventricular tachycardia was electrophysiologically induced during therapy with multiple antiarrhythmic drugs. Seven patients had previous myocardial infarction and five of them were high risk candidates for surgical therapy. One patient without organic heart disease had repetitive ventricular tachycardia manifesting two different patterns of left bundle branch block. After endocardial mapping, synchronized unipolar 250 to 300 J shocks (one to six) were delivered between the pole recording the earliest endocardial activity during ventricular tachycardia (40 to 200 ms before the onset of the QRS complex) and a body surface electrode. Immediate complications included severe but reversible cardiogenic shock (one patient), nonclinical ventricular tachycardia (two patients, requiring cardioversion in one), transient atrioventricular and intraventricular conduction disturbances (three patients) and permanent left bundle branch block (one patient). A late complication in one patient, left heart failure, occurred 3 days after delivery of five intracardiac shocks. In two patients, left ventricular ejection fraction markedly decreased and in one of them new ventricular contraction abnormalities appeared. Clinical ventricular tachycardia did not recur in five of the seven post-myocardial infarction patients after 7 to 17 months, and it was not inducible in the four patients undergoing late electrophysiologic study. In the patient with idiopathic ventricular tachycardia, one of the configurational types of ventricular tachycardia recurred.(ABSTRACT TRUNCATED AT 250 WORDS)