Incidence and electrocardiographic localization of safe right bundle branch block configurations during permanent ventricular pacing

Three-dimensional echocardiography definitively delineates a malpositioned permanent pacing lead in a patient with chronic chest pain

Inadvertent malpositioning of a cardiac pacing lead into the left heart chambers is a rare complication of transvenous pacing. We report a patient with a history of a transient ischemic attack and chronic chest pain whose left atrial pacing lead location was revealed by transesophageal three-dimensional (3D) echocardiography during evaluation of an inter-atrial shunt.

What is the diagnosis?

Paced right bundle branch block pattern in an elderly woman

A pacemaker lead in the left ventricle: An "unexpected" finding?

Inadvertent malposition of a pacemaker lead in the left ventricle is uncommon, but it should not be misdiagnosed. We report the case of a 68-year-old woman with symptomatic sick-sinus syndrome requiring pacemaker implantation. Shortly afterwards the lead was extracted and a new pacemaker was contralaterally implanted due to pocket hematoma and suspected lead fracture. Three months later, she was referred to our echocardiography laboratory complaining of asthenia. At transthoracic echocardiography an echo-bright linear structure was recognized in left atrium, passing through the mitral valve and leaning against the posterior left ventricular wall. In short-axis and apical views, the lead apparently crossed the interatrial septum through patent foramen ovale. The QRS-paced electrocardiogram showed right bundle branch block morphology. The lead was apparently well positioned, examining the chest X-ray postero-anterior view. On the contrary, by latero-lateral view and left-anterior oblique view, lead curvature was consistent with misplacement into the left ventricle. Malposition was confirmed by transesophageal echocardiography. Given the relatively recent implant, system revision with lead extraction was scheduled and completed without complications. This case report is intended to improve our awareness in the prevention and in the prompt detection of misplaced pacemaker leads in order to manage an immediate correction. <Learning objective: During lead implantation, fluoroscopic left-anterior oblique view should be always used to ensure correct positioning. At least 3-6 limb leads should be carefully monitored during the procedure, and a 12-lead standard electrocardiogram should be performed shortly afterwards for the paced QRS morphology. Lateral chest X-ray should always be taken after implantation. In cases of doubt, echocardiography (transthoracic or transesophageal) may confirm abnormal lead placement defining the route covered by the catheter.>.

Inadvertent Left Ventricle Endocardial or Uncomplicated Right Ventricular Pacing: How to Differentiate in the Emergency Department

BACKGROUND

Temporary transvenous pacemaker implantation is an important and critical procedure for emergency physicians. Traditionally, temporary pacemakers are inserted by electrocardiography (ECG) guidance in the emergency department because fluoroscopy at the bedside in an unstable patient can be limited by time and equipment availability. However, in the presence of atrial septal defect, ventricular septal defect, and patent foramen ovale, the pacemaker lead can be implanted inadvertently into the left ventricle or directly into the coronary sinus instead of right ventricle. Regular pacemaker rhythm can be achieved despite inadvertent implantation of the pacemaker lead into the left ventricle, leading to ignorance of the possibility of lead malposition.

CASE REPORT

A 65-year-old female patient with hemodynamic instability and complete atrioventricular block underwent temporary pacemaker implantation via right jugular vein with ECG guidance at the emergency department. Approximately 12 h after implantation, it was noticed that the ECG revealed right bundle branch block (RBBB)-type paced QRS complexes. Diagnostic workup revealed that the lead was inadvertently located in the left ventricular apex. This case illustrates the importance of careful scrutiny of the 12-lead ECG and imaging clues in identifying lead malposition in the emergency department. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Because inadvertent left ventricle endocardial pacing carries a high risk for systemic embolization, it is important to determine whether an RBBB pattern induced by ventricular pacing is the result of a malpositioned lead or uncomplicated transvenous right ventricular pacing.

An Electrocardiographic Algorithm for Determining the Location of Pacemaker Electrode in Patients With Right Bundle Branch Block Configuration During Permanent Ventricular Pacing

The expected morphology of right ventricular pacing is a left bundle branch block (LBBB) pattern. However, right bundle branch block (RBBB) can also be seen during permanent right ventricular pacing. The aim of this study was to develop an electrocardiographic algorithm to differentiate this benign condition from septal and free wall perforation with subsequent left ventricular pacing. Three hundred consecutive patients who had permanent ventricular or dual-chamber pacemaker implantation between 1999 and 2000 were screened and 25 patients (8.3%) who exhibited RBBB configuration were included in the study. Echocardiograms and chest radiographs were evaluated in order to identify the pacing lead location in this group. The authors formed a study group with their own 25 patients and 22 cases of RBBB with permanent pacemaker from previous publications (total 47 patients). Frontal axis, QRS morphology in lead V1, and the precordial transition point, which is defined as the precordial lead where R wave amplitude is equal to S wave amplitude, were examined. Placement of precordial leads V1 and V2 1 interspace lower than the standard location (Klein maneuver) eliminated the RBBB pattern in 12 patients. RBBB pattern with “true right ventricular pacing” was detected in 24 of the 25 patients, and in 11 of the 22 patients reported in the literature (total 35 patients). Right ventricular pacing was correctly identified in 34 of 35 patients with use of criteria including left superior axis deviation, RS or qR morphology in lead V1, and precor-dial transition at lead V3 with a high sensitivity and specificity. A simple surface electrocardiogram can accurately predict the lead location in patients having RBBB morphology with right ventricular pacing.

Right Bundle Branch Block-Like Pattern During Uncomplicated Right Ventricular Pacing and the Effect of Pacing Site

Right bundle branch block (RBBB) configuration is an unexpected finding during right ventricular (RV) pacing that raises the suspicion of inadvertent left ventricular lead positioning. The aim of this study was to evaluate the prevalence of paced RBBB pattern in relation to RV lead location. This is a secondary analysis of a prospective, multicenter study, which randomized implantable cardioverter defibrillator recipients to an apical versus midseptal defibrillator lead positioning. A 12-lead electrocardiogram was recorded during intrinsic rhythm and RV pacing. Paced RBBB-like pattern was defined as positive (>0.05 mV) net amplitude of QRS complex in leads V1 and/or V2. In total, 226 patients (65.6 ± 12.0 years, 20.8% women, 53.1% apical site) were included in the study. The prevalence of paced RBBB pattern in the total population was 15.5%. A significantly lower percentage of patients in the midseptal group demonstrated RBBB-type configuration during RV pacing compared with the apical group (1.9% vs 27.5%, p <0.001). Baseline RBBB, prolonged QRS duration during intrinsic rhythm, and reduced ejection fraction were not associated with increased likelihood of paced RBBB. In the subgroup of patients with RBBB type during pacing, 91.4% of patients had a paced QRS axis from -30° to -90°, whereas 100% of patients displayed a negative QRS vector at lead V3. In conclusion, RBBB configuration is encountered in a considerable percentage of device recipients during uncomplicated RV pacing. Midseptal lead positioning is associated with significantly lower likelihood of paced RBBB pattern compared with apical location.

An Unconventional Route of Left Ventricular Pacing

We present a case of a rare complication of transvenous right ventricular pacing by temporary pacing wire causing iatrogenic interventricular septal perforation and left ventricular pacing in a 69-year-old man who was referred for recurrent syncope with sinus arrest.

A change in QRS morphology in right ventricular apical pacing: is it a red flag sign?

A 74-year-old man with symptomatic complete heart block underwent right ventricular apical permanent pacemaker implantation. The postoperative ECG showed, as expected, completely paced left bundle branch block QRS morphology. However, at the 2-month follow-up examination, his ECG showed paced right bundle branch block (RBBB) QRS morphology, although the patient was asymptomatic. On evaluation, pacemaker functioning was normal with no evidence of lead displacement. This case report highlights that RBBB morphology of paced QRS complex is not always a red flag sign.

Diagnostic Value of the 12-Lead Electrocardiogram during Conventional and Biventricular Pacing for Cardiac Resynchronization

The paced 12-lead ECG is a valuable tool in the assessment of patients with pacemakers, and ideally should be recorded routinely at the time of implantation and during follow-up. It has become particularly important in patients undergoing cardiac resynchronization. The multiplicity of clinical situations described in this review highlight the pitfalls of using a single ECG lead in the overall evaluation of pacemaker patients. The design of programmers capable of registering a 12-lead ECG would obviate the need of an additional electrocardiograph and encourage the routine recording of the paced 12-lead ECG with each patient encounter. Such an arrangement would improve the care of pacemaker patients.

Two-Dimensional Echocardiography for the Diagnosis of Interventricular Septum Perforation by a Temporary Pacing Catheter

This case study describes a patient with complete heart block inadvertently paced from the left ventricular posterior wall due to perforation of interventricular septum by a temporary pacing catheter. This is a rare but potentially fatal complication of pacing. The frontal chest radiograph neither identified abnormalities nor could determine the exact site of the catheter tip. The electrocardiogram revealed a right bundle branch block pattern. Echocardiography was performed immediately at bedside and the diagnosis was made. The temporary pacing catheter was removed without complications and, the next day, the patient underwent permanent pacemaker implantation. Given its noninvasiveness and availability, echocardiography is a highly effective means of assessing pacemaker complications such as catheter perforation.

Right ventricular enlargement mimicking electrocardiographic left ventricular pacing

Electrocardiographic right bundle branch block morphology during cardiac pacing is occasionally the result of accidental placement of pacemaker or defibrillator leads into the left ventricle. Inadvertent lead placement in the left heart is associated with a risk of systemic embolism. Previous authors have attempted to define safe (right ventricular origin) and unsafe (left ventricular origin) patterns of right bundle branch block during pacing. We report a case of a patient with severe dilated cardiomyopathy and a correctly positioned pacemaker-defibrillator lead in the right ventricular apex, who meets electrocardiographic criteria for lead implantation into the left ventricle.

Electrocardiographic follow-up of biventricular pacemakers

Multisite pacing for the treatment of heart failure has added a new dimension to the electrocardiographic evaluation of device function. During left ventricular (LV) pacing from the appropriate site in the coronary venous system, a correctly positioned lead V1 registers a right bundle branch block pattern with few exceptions. During biventricular stimulation associated with right ventricular (RV) apical pacing, the QRS is often positive in lead V1. The frontal plane QRS axis is usually in the right superior quadrant and occasionally in the left superior quadrant. Barring incorrect placement of lead V1 (too high on the chest), lack of LV capture, LV lead displacement or marked latency (exit block or delay from the stimulation site), ventricular fusion with the spontaneous QRS complex, a negative QRS complex in lead V1 during biventricular pacing involving the RV apex probably reflects different activation of an heterogeneous biventricular substrate (ischemia, scar, His-Purkinje participation in view of the varying patterns of LV activation in spontaneous left bundle branch block) and does not necessarily indicate a poor (electrical or mechanical) contribution from LV stimulation. In this situation, it is imperative to rule out the presence of coronary venous pacing via the middle cardiac vein or even unintended placement of two leads in the RV. During biventricular pacing with the RV lead in the outflow tract, the paced QRS in lead V1 is often negative and the frontal plane paced QRS axis is often directed to the right inferior quadrant (right axis deviation). In patients with sinus rhythm and a relatively short PR interval, ventricular fusion with competing native conduction during biventricular pacing may cause misinterpretation of the ECG because narrowing of the paced QRS complex simulates appropriate biventricular capture. This represents a common pitfall in device follow-up. Elimination of ventricular fusion by shortening the AV delay, is often associated with clinical improvement. Anodal stimulation may complicate threshold testing and should not be misinterpreted as pacemaker malfunction. One must be cognizant of the various disturbances that can disrupt 1:1 atrial tracking and cause loss of ventricular resynchronization. (1) Upper rate response. The upper rate response of biventricular pacemakers differs from the traditional Wenckebach upper rate response of conventional antibradycardia pacemakers because heart failure patients generally do not have sinus bradycardia or AV junctional conduction delay. The programmed upper rate should be sufficiently fast to avoid loss of resynchronization in situations associated with sinus tachycardia. (2) Below the programmed upper rate. This may be caused by a variety of events (especially ventricular premature complexes and favored by the presence of first-degree AV block) that alter the timing of sensed and paced events. In such cases, atrial events become trapped into the postventricular atrial refractory period at atrial rates below the programmed upper rate in the presence of spontaneous AV conduction. Algorithms are available to restore resynchronization by automatic temporary abbreviation of the postventricular atrial refractory period.

Cardiac pacing: the state of the art

Permanent cardiac pacing remains the only effective treatment for chronic, symptomatic bradycardia. In recent years, the role of implantable pacing devices has expanded substantially. At the beginning of the 21st century, exciting developments in technology seem to happen at an exponential rate. Major advances have extended the use of pacing beyond the arrhythmia horizon. Such developments include dual-chamber pacers, rate-response algorithms, improved functionality of implantable cardioverter defibrillators, combinations of sensors for optimum physiological response, and advances in lead placement and extraction. Cardiac pacing is poised to help millions of patients worldwide to live better electrically. We review pacing studies of sick-sinus syndrome, neurocardiogenic syncope, hypertrophic obstructive cardiomyopathy, and cardiac resynchronisation therapy, which are common or controversial indications for cardiac pacing. We also look at the benefits and complications of implantation in specific arrhythmias, suitability of different pacing modes, and the role of permanent pacing in the management of patients with heart failure.

From lysosome to proteasome: the power of yeast in the dissection of proteinase function in cellular regulation and waste disposal

The yeast Saccharomyces cerevisiae has turned out to be an invaluable tool in the molecular biological sciences for elucidating the housekeeping functions of eukaryotic cells. Due to its easy amenability to biochemical, genetic, molecular biological and cell biological experimentation, including genomics and proteomics, yeast has become one of the most frequently used eukaryotic model organisms. One of the fields where studies in yeast have a truly pacemaking character is cellular control by proteolysis. The function of vacuolar (lysosomal) proteolysis was elucidated. The in vivo role of ubiquitin and its relation to the proteasome was uncovered. This research led to an avalanche of studies in many different eukaryotic systems, including mammals, and provided us with surprising new insights in cellular control in health and disease.

An unusual way to diagnose asymptomatic right ventricular perforation by a temporary endocardial pacing electrode

Right ventricular perforation by a temporary endocardial pacing electrode can be fatal and needs to be detected promptly. This usually symptomatic situation is diagnosed by X-ray or echocardiographic findings. We present the case of a patient with an asymptomatic right ventricular perforation, in whom serial electrocardiograms enabled us to detect the displacement of the right ventricular lead.

Safe right bundle branch block pattern during permanent right ventricular pacing

It is known that an electrocardiogram (ECG) after transvenous right ventricular (RV) pacing should yield left bundle branch block (LBBB) QRS patterns. When right bundle branch block (RBBB) pacing morphology appears in a patient with a permanent or temporary transvenous RV pacemaker, myocardial perforation or malposition of the pacing lead must be ruled out, even though the patient may be asymptomatic. We report a case of a 77-year-old man who underwent permanent transvenous VDD pacemaker implantation for symptomatic heart block. The postoperative ECG revealed a RBBB pacing configuration, but his chest X-ray and echocardiographic studies confirmed uncomplicated RV pacing. We review and discuss the literature concerning the differential diagnosis of such a safe RBBB ECG pattern.

VDD pacing from the middle cardiac vein via a persistent left superior vena cava

We report a combination of unusual features demonstrating a permanent pacemaker implantation of a single-pass VDD lead by way of an anomalous persistent left superior vena cava in the middle cardiac vein. The ventricular stimulation resembled a right bundle branch block QRS morphology and was successfully synchronized by spontaneous atrial activity. This case illustrates an alternative approach of effective VDD pacing and sensing in patients with such a venous anomaly when other standard implantation sites fail.