Pre-existing Left Bundle Branch Block Research Articles

0318 : Left bundle branch block after transcatheter aortic valve implantation: incidence, predictive factors and outcome

Conduction disorders are frequent after transcatheter aortic valve implantation (TAVI). The aim of the study was to assess the incidence, the clinical impact and the predictive factors of new-onset left bundle branch block (LBBB) after TAVI. Between 2010 and 2014, 198 consecutive patients underwent TAVI in our center and 156 were prospectively followed during 1 year (62 CoreValve (CV), 94 Edwards Sapiens valve (ES)). 42 patients were excluded because of a pre-existing PM before TAVI, death or surgery after TAVI. After 156 TAVI, 40 patients (26%) required pacemaker implantation. CV patients were more frequently implanted than ES (35% vs 19%; p=0.03). Out of 116 non-implanted patients, 53 (46%) patients presented with LBBB which persisted in 35 (30%) patients. QRS width increased +27ms in post-procedure, +21ms at hospital discharge, +15ms at 1 month, +11ms at 1 year in the whole cohort. There was no clinical nor echocardiographic difference between the LBBB group and no-LBBB group. Ischemic neurological complication were more frequent during hospitalization in the LBBB group (8.6% vs 3.7%; p=0.007). On multivariate analysis, a pre-existing incomplete LBBB (OR 4.15; IC 1.31-13.11; p=0.015) and a long pre-procedure PR interval (OR 1.023; IC 1.001-1.046; p=0.038) were predictive factors of new persistent LBBB after TAVI and a trend with CV implantation was observed (OR 2.35; IC 0.99- 5.53; p=0.051). NYHA grade was increased in the LBBB group compared to non-LBBB group at 1 (2,1 ± 0,8 vs 1,7 ± 0,6 ; p=0.006), 6 (2,21 ± 0,7 vs 1,53±0,6 ; p=0.001) and 12 months (2.2 vs 1.7, p=0.04). On univariate analysis, a pre-existing atrial fibrillation (OR 2.1; IC 1.12- 4.01; p=0.021), an initial mean aortic gradient (OR 0.78; IC 0.65-0.93; p=0.006) and new LBBB after TAVI (OR 2.06; IC 1.05-4.04; p=0.036) were predictive factors of mortality at 12 months. On multivariate analysis, LBBB after TAVI was an independent predictor of mortality (OR 3.52; IC 1.17- 10.58, p=0.025). New-onset LBBB is frequent after TAVI and persists in a great proportion of patients. In our study, LBBB after TAVI was an independent predictor of mortality.

Complete atrioventricular block during tunneled cuffed hemodialysis catheter insertion in a patient with pre-existing left bundle branch block

Arrhythmias are complications of tunneled cuffed hemodialysis catheter insertion. Most complications associated with arrhythmias occur during guide-wire access, where the guide wire can cause traumatic damage to the conduction system of the heart. Conducting system injury in tunneled cuffed hemodialysis catheter insertion often involves the right bundle, causing right bundle branch block (RBBB). Transient RBBB with sinus rhythm is not usually accompanied by abnormal vital signs. However if patients already have left bundle branch block (LBBB), new onset RBBB can cause complete atrioventricular block (AVB), which can lead to fatal complications requiring invasive treatment. We report on a patient with LBBB who developed complete AVB during hemodialysis catheter insertion.

ELECTROCARDIOGRAPHIC DIAGNOSIS OF ACUTE MYOCARDIAL INFARCTION IN PACED RHYTHMS: UTILITY OF THE SGARBOSSA CRITERIA

ELECTROCARDIOGRAPHIC DIAGNOSIS OF ACUTE MYOCARDIAL INFARCTION IN PACED RHYTHMS: UTILITY OF THE SGARBOSSA CRITERIA

Insights Into New-Onset Rhythm Conduction Disorders Detected by Multi-Detector Row Computed Tomography After Transcatheter Aortic Valve Implantation

New-onset rhythm conduction disorders are frequent after transcatheter aortic valve implantation (TAVI). Multidetector row computed tomography may shed light on the pathophysiology of rhythm conduction disorders in patients who undergo TAVI with the Edwards SAPIEN valve. A total of 94 patients (mean age 81 ± 7 years, 48% men) treated with TAVI with the Edwards SAPIEN valve who underwent pre- and post-TAVI multidetector row computed tomography were included. Patients with preexisting right bundle branch block or left bundle branch block (LBBB) and permanent pacemakers were excluded. Pacemaker implantation or new-onset LBBB at 1-month follow-up was the combined end point. Overall, 1 pacemaker was implanted, and 14 cases of new-onset LBBB were recorded. Among several clinical and multi-detector row computed tomographic variables, overexpansion of the transcatheter valve >15% of native annular area (odds ratio 5.277, 95% confidence interval 1.398 to 19.919, p = 0.014) and depth of frame into the left ventricular outflow tract (odds ratio 1.401, 95% confidence interval 1.066 to 1.770, p = 0.010) were independently related to the need for a pacemaker or new-onset LBBB. In conclusion, overexpansion of the transcatheter prosthesis by >15% of native aortic annular area and implantation depth of the frame into the left ventricular outflow tract were independently associated with the need for a pacemaker or new-onset LBBB in patients who underwent TAVI with the Edwards SAPIEN valve.

Initial complications and factors related to prehospital mortality in acute myocardial infarction with ST segment elevation

ObjectiveHospital mortality in myocardial infarction ST-elevation myocardial infarction has decreased in recent years, in contrast to prehospital mortality. Our objective was to determine initial complications and factors related to prehospital...

Comprehensive Dobutamine Stress CMR Versus Echocardiography in LBBB and Suspected Coronary Artery Disease

This study aimed to compare dobutamine stress cardiac magnetic resonance (DSCMR) withdobutamine stress echocardiography (DSE) in patients with left bundle branch block (LBBB) and suspected coronary artery disease (CAD). Noninvasive diagnosis of CAD in patients with pre-existent LBBB is difficult because single-photon emission computed tomography and stress echocardiography both have limitations. We hypothesized that a comprehensive DSCMR examination including cine, perfusion, and late gadolinium enhancement imaging would be more accurate than DSE, thus potentially reducing the number of unnecessary invasive coronary angiograms. We prospectively evaluated 82 consecutive patients with LBBB referred to our cardiology clinic for investigation of suspected CAD. All 82 patients underwent DSE, DSCMR, and invasive quantitative coronary angiography within 14 days. We compared the diagnostic accuracy of DSE, CMR cine imaging, the additive value of first-pass perfusion, and late gadolinium enhancement. In the comprehensive examination, a positive result was adjudged as the presence of either subendocardial or transmural late gadolinium enhancement with or without inducible peri-infarct ischemia or an inducible perfusion defect corresponding to an inducible regional wall motion abnormality. CMR cine imaging (regional wall motion abnormalities) had higher specificity, negative predictive value, and overall diagnostic accuracy than did DSE (87.5% vs. 72.9%; 80.8% vs. 67.3%; and 80.4% vs. 72.0%, respectively), although sensitivity was the same (72.0%). The addition of first-pass stress perfusion and late gadolinium enhancement (scar) further improved diagnostic confidence (sensitivity 82.4%, specificity 95.8%, positive predictive value 93.3%, negative predictive value 88.5%, and diagnostic accuracy 90.2%). DSCMR is a safe procedure and has greater diagnostic accuracy than does DSE in assessing patients with suspected CAD and LBBB. A comprehensive examination with the addition of perfusion and late gadolinium enhancement to CMR cine imaging significantly boosted specificity and sensitivity, making DSCMR a reliable alternative to invasive quantitative coronary angiography in this group of patients.

Occurrence, fate and consequences of ventricular conduction abnormalities after transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) is frequently complicated by new left bundle branch block (LBBB). We investigated the development and persistence of LBBB during follow-up and its clinical consequences. ECGs at baseline, within 24 hours, before discharge and at 12 months after TAVI were assessed in 476 patients without pre-existing LBBB and/or pacemaker before or after TAVI. TAVI-induced new LBBB was categorised based on the timing of the occurrence (within 24 hours [acute], after 24 hours but before discharge [subacute], and after discharge [late]), in addition to persistence (transient or persistent). A total of 175 patients (36.8%) developed new LBBB of which 85.7% occurred within 24 hours after TAVI, 12.0% before and 2.3% after hospital discharge, and was persistent in 111 patients (63.4%). Implantation of the Medtronic CoreValve System (MCS) more frequently led to new LBBB than the balloon-expandable Edwards SAPIEN valve (ES) (53.8% versus 21.7%) with less recovery during follow-up (39.0% versus 9.5%). Late new LBBB was only seen in four patients (0.8%). During a median follow-up of 915 (578-1,234) days, persistent LBBB was associated with a significant increase in mortality as compared to no LBBB and temporary LBBB combined (hazard ratio 1.49, 95% confidence interval, 1.10-2.03; p=0.01). TAVI-induced new LBBB occurs in almost 40% of patients, almost all before hospital discharge. It occurs three times more frequently after MCS than after ES valve implantation and has a twofold lower tendency to resolve during follow-up. Persistent LBBB is associated with a higher mortality.

Lethal cardiac arrhythmia during central venous catheterization in a uremic patient: A case report and review of the literature

Double-lumen central venous catheter (CVC) is a rapid access technique for hemodialysis (HD) when an arteriovenous fistula or graft is not available. A variety of procedure-related complications have been reported, such as infection and pneumothorax, but serious cardiac complications are relatively less mentioned. We report a uremic woman with preexisting left bundle branch block who required emergent HD and received jugular double-lumen CVC insertion, which was complicated by short-duration ventricular tachycardia followed by complete atrio-ventricular block and bradycardia. Pharmacological management did not reverse heart rate and rhythm. External pacing was not applied because she remained hemodynamically stable in the course of HD. Heart rate returned to sinus rhythm with left bundle branch block 4 hours later and did not recur through the whole admission period. We speculate that the transient arrhythmia might have been induced by mechanical contact with the ventricular wall during the procedure with the guided metallic wire. In conclusion, physicians responsible for CVC catheterization should pay more attention to patients with preexisting cardiac arrhythmia to prevent such technical mistakes from transpiring.

Complete heart block—an underappreciated serious complication of central venous catheter placement

Central venous catheter (CVC) placement is a common bedside procedure that is frequently performed in critically ill patients. More than 5 million CVCs are inserted annually across the United States alone. Procedure-related complications may vary from minor bleeding to life-threatening complications such as arterial perforation and pneumothorax. Cardiac arrhythmias can often occur during the guidewire placement, and bundle-branch blocks have also been reported. We herewith report a case of complete heart block during CVC placement, which is a rare but serious complication of this procedure. Because the patient had a preexisting left bundle-branch block, complete heart block likely resulted from a probable trauma to the right bundle branch during the guidewire insertion.

Specificity of the wide QRS complex tachycardia algorithms in recipients of cardiac resynchronization therapy

BackgroundWe assessed the specificity of wide QRS complex tachycardia (WCT) differentiating algorithms in patients with preexistent left bundle branch block (LBBB) and heart failure. MethodsThree hundred fourteen patients with resynchronization devices were retrospectively screened. electrocardiograms with supraventricular LBBB rhythm were used as a surrogate for supraventricular tachycardia QRS morphology. The Pava lead II criterion, ventricular activation velocity ratio (Vi/Vt) ratio in V2, Vereckei aVR, Brugada, Griffith, and Bayesian algorithms were investigated. ResultsThe WCT algorithms had a lower specificity (33%-69%) in patients with LBBB than in general WCT populations. The Pava lead II criterion and Brugada algorithm had higher specificity than other algorithms (P < .05). Several of the single criteria (absence of an RS complex in V1 through V6, initial R wave in aVR, Vi/Vt < 1 in V2) had specificities of 92% to 99%. ConclusionsIn patients with heart failure and LBBB, an electrocardiographic diagnosis of ventricular tachycardia should be based on selected, specific criteria rather than on WCT algorithms.

Acute Myocardial Infarction due to Coronary Artery Embolism in a Patient with a Tissue Aortic Valve Replacement

Acute occlusive embolism to the coronary arteries resulting in acute myocardial infarction (AMI) is an uncommon occurrence. Although cases of patients with mechanical prosthetic heart valves resulting in this phenomenon have been reported in the setting of inadequate anticoagulation, reported cases resulting years after tissue aortic valve replacement (AVR) are rare. We report the case of a 50-year-old man who underwent a tissue AVR four years earlier and presented to the Emergency Department (ED) with an ST-segment elevation myocardial infarction. ED door-to-balloon time was delayed (at 115 minutes) because of pre-existing left bundle branch block on electrocardiogram. Emergent coronary angiography demonstrated complete occlusion of the left anterior descending coronary artery by a coronary embolus. The patient was successfully treated with percutaneous transluminal coronary angioplasty and aspiration thrombectomy, and subsequently underwent a transesophageal echocardiogram demonstrating thrombus on the tissue aortic valve prosthesis. This case demonstrates that coronary embolism resulting in AMI, while rare, can occur in patients years after tissue AVR surgery.

Atrioventricular block during radiofrequency catheter ablation of atrial flutter: incidence, mechanism, and clinical implications

To evaluate the incidence, mechanism, and clinical implications of atrioventricular (AV) block during catheter radiofrequency (RF) ablation of the cavotricuspid isthmus (CTI). Although RF ablation of atrial flutter is the most frequently performed ablation procedure, data on the incidence and significance of an AV block occurring during the procedure are scarce. Consecutive patients (n=845, 73.5% male) undergoing CTI ablation (913 procedures) between 1998 and 2010 were studied. Data on the occurrence of complete AV block (lasting≥3 s) during the procedure were prospectively collected. Sixteen (1.9%) patients experienced AV block, 12 during delivery of RF pulses (Group 1) and 4 (Group 2) during manipulation of catheters in the cardiac chambers. The AV block was short lived (<1 min), located in the AV node, and associated with septal isthmus RF lines in 11 Group 1 patients. It was long-lasting and led to pacemaker implantation in one Group 1 patient. Atrioventricular blocks had an infranodal location in four Group 2 patients, all of whom had a pre-existing complete left bundle branch block (LBBB). One Group 2 patient had an AV block during his two ablation procedures. Permanent pacemakers were implanted in five (0.6%) patients (one from Group 1 and four from Group 2). Atrioventricular blocks requiring pacemaker implantation following administration of RF pulses at the CTI are rare (0.12%). The occurrence rate of AV block related to the procedure and requiring pacemaker implantation is, however, not negligible (0.6%) and mostly affects patients with a pre-existing complete LBBB.

Complete atrioventricular block during central venous catheter placement with pre-existing left bundle branch block: Preparedness guidelines

Injury to the right bundle causing Right Bundle Branch Block (RBBB) is a known complication of central line placement. Complete heart block may result in patients with pre-existing Left Bundle Branch Block (LBBB). There are no organized guidelines for preparedness in such condition. Seventy-eight-year old woman presented with intraparenchymal hemorrhage. Venous access was obtained in the right subclavian vein and guide wire was passed. As the catheter was passed over the guidewire, the rhythm went in complete heart block. She was paced with an external pacemaker. Review of her EKG revealed pre-existing LBBB.Clinicians should check the EKG before attempting central line placement in an elective/semi-emergent situation. Familiarize with the catheter and guide wire lengths/markings of the available kit.

Short-Term Effect on Left Ventricular Function Post-Transcatheter Aortic Valve Implantation (TAVI) Related New Onset of Left-Bundle Branch Block

Background: TAVI is performed at Waikato hospital for patients with severe symptomatic aortic stenosis considered unsuitable for aortic valve surgery due to high risk. Concern exists on the potential development of new left-bundle branch block (LBBB) post TAVI and the possible deleterious effect of this rhythm disturbance on left ventricular function. We report our observed incidence of new onset of LBBB and the changes of ejection fraction at one-month follow-up. Methods: Over a two-year period, from August 2008, 47 patients underwent successful TAVI, 30 patients had self-expandable CoreValves (Medtronic, Minneapolis, USA) and 17 had balloon-expandable Edwards Sapien (Edward Lifescience, Irvine, USA). All patients had electrocardiography and echocardiography pre-procedure and at one-month follow-up. Left ventricular ejection fraction (LVEF) was assessed by Simpson's bi-plane method. The change of LVEF for individual patients was calculated (LVEF at one-month – LVEF before procedure). Twelve patients were excluded from the study: two did not survive the procedure, seven had pre-existing LBBB, one was pacemaker dependent prior to the procedure and two did not survive passed one month. Results: Thirty-seven patients were included in the analysis with a mean age of 80 ± 8 years-old; 57% were male. Fourteen (38%) patients had new onset of LBBB (n = 10, 27%) or pacemaker-related LBBB (n = 4, 11%). The results are summarised in the table below.Tabled 1New LBBB + PPMNo LBBBP ValuePatient no.1223Age, years79 ± 980 ± 60.55Male, %7 (58%)14 (61%)1.00CoreValve (MCV) n, %11 (44%)14 (56%)MCV vs EVEdwards Sapien Valve (EV) n, %1 (10%)9 (90%)0.11Baseline LVEF, %53 ± 1755 ± 150.74LVEF at 1 month, %62 ± 760 ± 80.33Change of LVEF at 30 days, %+9 ± 16%+5 ± 130.36No. of patients LVEF reduced ≥5% at 30 days2, 17%6, 26%0.69 Open table in a new tab Conclusion: A new onset of LBBB post TAVI does not appear to have an adverse effect on the left ventricular ejection fraction in the short-term.

Prediction of Cardiac Events in Patients Having Left Bundle-Branch Block with/without Chest Pain Using Dipyridamole Technetium-99m-Sestamibi Myocardial Perfusion Imaging

Objective: To determine the prognostic value of myocardial perfusion scintigraphy with dipyridamole stress in patients with preexisting left bundle-branch block (LBBB) with or without chest pain. Subjects and Methods: Seventy-six patients, mean age 53 ± 10 years, with preexisting LBBB underwent technetium-99m-sestamibi perfusion imaging with dipyridamole infusion protocol (0.56 mg/kg). Stress and rest single photon emission computed tomography (SPECT) images were interpreted by consensus of 2 experienced nuclear medicine physicians and classified as low-risk scans (normal myocardial perfusion scan, small reversible/small fixed defect) and high-risk scans (large, severe, fixed or reversible defect and dilated left ventricle cavity). The patients were followed up for 24 ± 8 months and occurrences of hard cardiac events (infarction or cardiac death) were noted. Results: Of the 76 patients, 52 (68%) had low-risk scans and the remaining 24 (32%) had high-risk scans. In the low-risk group, 1 (1.9%) cardiac death and 2 (3.8%) cases of nonfatal myocardial infarction occurred, while in the high-risk group, 5 (20.8%) suffered cardiac death, and 3 (12.5%) nonfatal myocardial infarction. Overall survival rate was 98.1% in the low-risk group compared with 79.2% in the high-risk group with a significant difference of p = 0.034. Negative predictive value of normal myocardial perfusion scintigraphy for the occurrence of death was 100%. No significant difference in survival rate among patients with or without chest pain (p = 0.31) was observed. Conclusions: Myocardial perfusion imaging with dipyridamole provided important prognostic information in patients with LBBB; it was useful in stratifying the patients according to cardiovascular morbidity and mortality, and would thus allow the clinician to provide early treatment especially in the high-risk category.

Percutaneous septal ablation after unsuccessful surgical myectomy for patients with hypertrophic obstructive cardiomyopathy

To evaluate the long-term outcome of percutaneous septal ablation (PTSMA) after a previous myectomy. Myectomy usually results in symptomatic improvement and reduction of dynamic obstruction in hypertrophic obstructive cardiomyopathy patients (HOCM-pts.). However, a few pts. remain with severe symptoms and obstruction, and need additional interventions. We reviewed our database of 450 pts. who underwent PTSMA in our institution, and identified 11 (7 women, 4 men, mean age: 50 +/- 14 years) with residual or recurrent NYHA class symptoms > or =III and significant left ventricular outflow obstruction (LVOTO) despite a previous myectomy 4 +/- 5 years ago. In-hospital and follow-up data covering 6 +/- 4 years, focusing on mortality and morbidity, symptoms, exercise capacity, and echocardiographic measures were collected. PTSMA was performed by injection of 3.6 +/- 2.9 ml of alcohol. There was no peri-procedural or late death in this cohort. CK peaked at 614 +/- 434 U/l. In addition to two pts. who already had a pacemaker implanted, two more (18%) who both had pre-existing left bundle branch block were pacemaker-dependent after PTSMA. During follow-up, 9 pts. (81%) reported significant and stable improvement. Two pts. (18%) developed progressive class III symptoms until their last follow-up, one of these together with persistent AF and a non-fatal stroke, the other received an ICD for primary prophylaxis and entered our pre-transplant program. Echo-Doppler showed sustained LVOTO elimination without global LV dilatation in all cases. PTSMA is an effective non-surgical option for treating symptoms and residual or recurrent LVOTO after a previous surgical myectomy. The high rate of conduction disturbances in this post-surgical cohort translated into a higher rate of pacemaker dependency after PTSMA.

Reinitiation of Ventricular Macroreentry within the His‐Purkinje System by Back‐Up Ventricular Pacing—A Mechanism of Ventricular Tachycardia Storm

We describe immediate reinitiation of macroreentry ventricular tachycardia (VT) involving the His-Purkinje system by ventricular pacing from the electrode of an implantable cardioverter defibrillator (ICD) as a mechanism of VT storm refractory to ICD therapy. Repetitive reinitiation of bundle branch reentry tachycardia (BBRT), interfascicular tachycardia, or both VTs by ventricular pacing was identified in four ICD patients presenting with VT storm or incessant VT. All patients had a pre-existing prolonged HV interval (75 +/- 9 ms) and left bundle branch block (LBBB) or bifascicular block during sinus rhythm. The VTs included BBRT with LBBB in three patients and interfascicular tachycardia with right bundle branch block (RBBB) and left anterior or left posterior fascicular block in two patients. The paced beats from the ICD electrode exhibited a LBBB pattern of depolarization in two patients and a RBBB contour in V1 and V2 with left axis deviation in two patients. The QRS complex during pacing from the ICD electrode closely resembled that of the recurrent VT in all four patients suggesting that the pacing site of the ICD electrode was in proximity to the myocardial exit site of the bundle fascicle used for antegrade conduction during the reinitiated VT. Ventricular pacing from the ICD electrode after termination of the VT apparently encountered the retrograde refractoriness of this bundle fascicle and allowed immediate re-propagation of the wavefront orthodromically along the VT circuit. BBRT was eliminated by ablation of the right bundle branch. Successful ablation of the interfascicular tachycardias was achieved by targeting (1) an abnormal potential of the distal left posterior Purkinje network or (2) a diastolic potential during VT in the midinferior left ventricular (LV) septum. Repetitive reinitiation of BBRT and interfascicular tachycardia by ventricular pacing from the ICD electrode should be considered as a mechanism of VT storm refractory to ICD therapy in patients with a pre-existing conduction delay within the His-Purkinje system.

Conduction system abnormalities in patients with obstructive hypertrophic cardiomyopathy following septal reduction interventions

We observed the impact of percutaneous transluminal septal myocardial ablation (PTSMA) and myectomy on the conduction system in patients with obstructive hypertrophic cardiomyopathy (HC). Septal reduction intervention is capable of eliminating the left ventricular outflow tract obstruction in patients with obstructive HC; however, conduction system abnormalities are frequent consequences of these procedures. A standard 12-lead electrocardiogram and Doppler echocardiogram were obtained in 204 patients who underwent PTSMA (n = 70) or myectomy (n = 134) before and at average of 3 months after intervention. Of 146 patients who had normal conduction systems before intervention, the duration of the QRS complex was significantly prolonged from 98 ± 15 to 130 ± 25 ms (p <0.0001), with right bundle branch block (RBBB) developing in 62% patients after PTSMA, and from 100 ± 13 to 154 ± 20 ms (p <0.0001), with left bundle branch block (LBBB) developing in 93% patients after myectomy. No significant difference in the QRS duration was found in the remaining 58 patients who had preexisting conduction abnormalities after intervention. In 174 patients without a preexisting permanent pacemaker, a pacemaker was implanted in 22% versus 13% of patients who underwent PTSMA (overall and without preexisting conduction block, respectively) and 10% versus 2% of patients with myectomy. The duration of baseline QRS was an independent predictor for the requirement of a permanent pacemaker (p <0.0001). Thus, RBBB often develops after PTSMA and LBBB is very frequently produced by myectomy. A possible requirement of a permanent pacemaker should always be considered before intervention when patients have preexisting RBBB or LBBB.

Electrocardiographic diagnosis of acute myocardial infarction in the presence of left bundle branch block.

It is often stated that the diagnosis of acute myocardial infarction (AMI) is extremely difficult if not impossible in the presence of left bundle branch block (LBBB). Likewise the electrocardiographic...

Inadvertent Catheter‐Induced Right Bundle Branch Block in a Patient with Preexistent Left Bundle Branch Block and Recurrent Macroreentrant Ventricular Tachycardia

This article describes the inadvertent, catheter-induced induction of right bundle branch block resulting not only in transient complete infra-His heart block but also in temporary interruption of the macroreentry circuit of ventricular tachycardia. A patient with preexistent left bundle branch block and spontaneous ventricular tachycardia based upon the bundle branch reentry mechanism underwent electrophysiological testing for the evaluation of sotalol drug efficacy. In search of an optimal His-bundle recording, the manipulation of a 6 Fr quadripolar catheter caused a right bundle branch block, thus advancing the preexistent left bundle branch block to complete heart block. Retrograde ventriculoatrial conduction remained unaffected. The macroreentrant tachycardia with left bundle branch block configuration was no longer inducible. While the patient continued on unchanged sotalol medication (320 mg/d) he required temporary pacing for 16 hours until the block subsided. A subsequent induction attempt demonstrated initiation of the tachycardia. Finally, guided by invasive testing, the patient successfully received amiodarone therapy (300 mg/d). The patient completed an uneventful follow up of 27 months. No progression of conduction delay was observed. This case suggests that the inadvertent induction of right bundle branch block prevents the initiation of ventricular tachycardias relying on bundle branch reentry. Therefore, missed diagnosis or misinterpretation of antiarrhythmic drug efficacy might occur if there is no electrophysiological reevaluation after right bundle branch recovery.