Cross-ventricular pacemaker-mediated tachycardia by myopotential induction during biventricular pacing

BACKGROUND: Patients in permanent atrial fibrillation treated for heart failure and ventricular asynchrony can be implanted with conventional dual chamber pacemakers (DDD) pacemakers used in the biventricular mode. The left ventricular lead is connected to the atrial channel. CASE REPORT: We report the case of a patient who developed ventriculo-ventricular pacemaker-mediated tachycardia (PMT) induced by myopotential sensing in the atrial channel, inhibiting left ventricular pacing. CONCLUSION: In the absence of specifically designed pacemakers, the use of DDD pacemakers in the biventricular mode requires certain precautions, such as anti-PMT mode activation, disabling automatic sensitivity, and lengthening the postventricular atrial refractory period (PVARP), or mode switch to DVIR.     

Cross-ventricular endless loop tachycardia during biventricular pacing

This report describes the development of an unusual pacemaker tachycardia in a patient with a conventional dual chamber pacemaker used for biventricular pacing in the VVIR mode. The atrial channel was connected to the left ventricle and the ventricular channel to the right ventricle. The tachycardia was sustained by sensing of the T wave by the "atrial channel" which triggered pacing by the "ventricular channel. " This "cross-ventricular" endless loop tachycardia is a reentrant pacemaker tachycardia like classic endless loop tachycardia and can be prevented by appropriate programming of the pacemaker.     

Triple-site ventricular pacing in a biventricular pacing system

This case report describes a patient with heart failure in whom a biventricular pacing system was successfully implanted. During control of the pacing system, three morphologies of the paced QRS complex could be elucidated. Right ventricular stimulation, biventricular stimulation, and biventricular pacing with additional stimulation from the anodal electrode of the right ventricular lead determined the morphologies.     

Inappropriate tachycardia detection by a biventricular implantable cardioverter defibrillator

This case describes "double counting" of intrinsic conduction due to the combination of intraventricular conduction delay and the merging of the electrograms from the right and left ventricle (coronary sinus) leads in a biventricular cardioverter defibrillator. This situation prompted asymptomatic antitachycardia pacing. Lengthening of AV conduction by betablocker solved the problem.     

Inhibition of biventricular pacemakers by oversensing of far-field atrial depolarization

This report describes two patients who exhibited far-field oversensing of the P wave by the ventricular channel of a DDD biventricular pacemaker implanted for the treatment of congestive heart failure. Oversensing probably occurred secondary to slight displacement of the left ventricular lead in the coronary venous system. Long-term reliable pacing was restored by decreasing the sensitivity of the ventricular channel.     

Asynchronous ventricular pacing: a rare cause of ventricular tachycardia

Asynchronous cardiac pacing may induce ventricuiar tachycardia and fibrillation, particularly in patients with ischemic heart disease and possibly other types of myocardial abnormalities. All patients with implanted asynchronous pacemakers, and those whose demand pacemakers operate in asynchronous mode for any reason, are to he considered at risk from this complication. In patients with serious myocardial abnormalities consistent demand pacing should be assured, even if it requires early pacemaker replacement. Anti-arrhythmic agents may prove useful for temporary suppression of pacemaker-induced arrhythmias. (PACE, Vol. 5, July-August, 1982)     

Cardiac vein angioplasty for biventricular pacing

Biventricular pacing for the treatment of congestive heart failure has consistently demonstrated improvement in quality-of-life and reduction in heart failure symptoms. Though the over-the-wire systems will be helpful in overcoming many existing obstacles to optimal lead placement, anatomic variability will still limit overall success. Cardiac vein angioplasty may be required for deployment of leads into tortuous or obstructed cardiac veins. This case report describes the angioplasty of a focal cardiac vein stenosis allowing for successful implantation of a left ventricular pacing lead. The safety of this procedure is unknown, though the risks may be acceptable in certain patients.     

Sequential biventricular pacing: evaluation of safety and efficacy

The study evaluated the clinical safety, performance, and efficacy of sequential biventricular pacing in the InSync III (Model 8042) biventricular stimulator in a multicenter, prospective 3-month study and assessed the proper functioning of features aiming at improving biventricular AV therapy delivery. The system was successfully implanted in 189 (95.9%) of 198 patients with symptomatic systolic heart failure and a prolonged QRS complex duration. Patients significantly improved their 6-minute hall walk distance (baseline 339 +/- 92 vs 3-month 422 +/- 127 meter, P < 0.001) and NYHA class (baseline 3.1 +/- 0.5 vs 3-month 1.9 +/- 0.7, P < 0.001). Echocardiographic optimization of sequential biventricular pacing showed an improvement in stroke volume compared to simultaneous stimulation (sequential 68 +/- 24 mL vs simultaneous 56 +/- 23 mL, P < 0.001) at baseline and at 3 months. In 88% (30/34) of the patients these improvements were seen within a small range of V-V delays of +/-20 ms and in 94% (32/34) within V-V delays of +/-40 ms. In contrast, programming beyond this range reduced stroke volume below that during simultaneous biventricular pacing. The device functioned as expected. LV lead dislodgement was observed in 12 patients and phrenic nerve stimulation required lead repositioning in 2 patients. Eight patients died during the study. Patient survival at 3 and 6 months was 97 +/- 2% and 94 +/- 2%, respectively. Cause of death was cardiac (n = 7), heart failure related (n = 3), arrhythmia related (n = 2), and unknown (n = 2). In conclusion, this sequential biventricular pacemaker was safe and efficacious.     

Strategy to Eliminate Inappropriate Shocks Secondary to T-Wave Oversensing in a Biventricular ICD

T-wave oversensing represents a common cause of inappropriate shocks in patients with implanted cardiac defibrillators. This case report demonstrates a strategy of device programming using V-V pace delay (sequential rather than simultaneous biventricular pacing) to eliminate T-wave oversensing without decreasing sensitivity to detect true tachyarrhythmia.     

Unexpected loss of atrial tracking caused by interaction between temporary and permanent right ventricular leads during implantation of a biventricular pacemaker

This report describes a patient who underwent implantation of an atriobiventricular pacemaker following AV junction ablation and insertion of a temporary right ventricular (RV) pacemaker. During implantation, intermittent loss of sinus P wave tracking occurred when the three permanent leads were connected to the generator. Analysis of marker annotation disclosed intermittent abnormal ventricular sensing that reinitiated postventricular atrial blanking and caused failure of P wave tracking. This phenomenon disappeared after removing the temporary RV lead, but not by turning off the temporary pacemaker. We assume that mechanical contact between the temporary and the permanent RV leads is the underlying mechanism.     

Ventricular activation sequence during left ventricular pacing promotes QRS complex oversensing in the atrial channel

Background: Left ventricular (LV)‐only pacing has a significant effect on delay in depolarization of parts of the ventricles that are likely oversensed in the right atrial channel. The study aimed to assess the impact of ventricular activation sequence on QRS oversensing and far‐field endless‐loop pacemaker tachycardia (ELT) in patients who received cardiac resynchronization therapy (CRT) devices. Methods: The study examined 102 patients with CRT devices. Oversensing artifacts in the atrial channel were inspected on intracardiac electrograms, and their timing with respect to the beginning of QRS was determined during DDD‐right ventricular (RV), DDD‐LV, DDD‐biventricular (BiV), and AAI pacing modes. The occurrence of ELT during DDD‐LV pacing with a postventricular atrial refractory period (PVARP) of 250 ms was also assessed. Results: The timing of oversensing artifacts (in relation to the beginning of surface QRS) was dependent on ventricular activation sequence, occurring promptly following intrinsic activation via the right bundle branch (47.1 ± 26.4 ms), later during RV pacing (108.7 ± 22.5 ms) or BiV pacing (109.4 ± 23.1 ms), and significantly later, corresponding to the final part of the QRS, during LV pacing (209.6 ± 40.0 ms, range: 140–340 ms, P < 0.001). Oversensing was significantly more frequent during LV than during RV pacing (35.3% vs 22.5%, P < 0.001). Far‐field ELT was observed in six patients. Conclusions: Oversensing artifacts in the atrial channel are likely caused by depolarization of the basal part of the right ventricle. The novel mechanism of QRS oversensing outside PVARP, caused by a reversed ventricular activation sequence during LV‐only pacing, may be important in some CRT patients. (PACE 2011; 34:1682–1686)     

Self-conversion of supraventricular tachycardia by rapid atrial pacing.

The use of pacemakers in the treatment of tachycardias is one of the most exciting and rapidly expanding applications of cardiac pacing. One of the more recent developments in this field has been the use of patient-activated radio frequency transmitted rapid atrial stimulation (RAS) in the treatment of paroxysmal supraventricular tachycardia (PSVT). Based on the previously established ability of asynchronous atrial pacing to interrupt a variety of re-entrant supraventricular rhythm disturbances, this modality of treatment is gaining increasing applicability in patients with PSVT associated with debilitating symptoms or other severe cardiovascular consequences in whom standard pharmacological regimens have either failed or are impossible to maintain for indefinite periods. This report describes our experience with five patients who underwent implantation of RAS units. The detailed electrophysiological studies required to ensure success and avoid any possible future complications are described. Over a follow-up period of four months to four years (mean 16 months) very few problems arose in the use of these units which have immeasurably improved the quality of life of the recipients. Our experience with RAS units has led to a few suggestions for future improvement and these are outlined in this report. The excellent patient acceptance and the reliability of this technique in terminating episodes of PSVT should, in the future, render RAS the treatment of choice in certain selected patients suffering from this common disorder.     

Physiologic pacing: new modalities and pacing sites

Right ventricular (RV) apical pacing impairs left ventricular function by inducing dys-synchronous contraction and relaxation. Chronic RV apical pacing is associated with an increased risk of atrial fibrillation, morbidity, and even mortality. These observations have raised questions regarding the appropriate pacing mode and site, leading to the introduction of algorithms and new pacing modes to reduce the ventricular pacing burden in dual chamber devices, and a shift of the pacing site away from the RV apex. However, further investigations are required to assess the long-term results of pacing from alternative sites in the right ventricle, because long-term results so far are equivocal. The potential benefit of prophylactic biventricular, mono-chamber left ventricular, and bifocal RV pacing should be explored in selected patients with a narrow QRS complex, especially those with impaired left ventricular function. His bundle pacing is a promising and evolving technique that requires improvements in lead technology.     

扩张型心肌病患者双心室起搏治疗的护理

双心室起搏可使左、右心室同步收缩，增加心输出量，改善心功能，纠正心衰。笔通过对7例行双心室起搏治疗扩张型心肌病患的护理，认为做好术前心理护理，术中密切配合，术后加强心电监护，密切观察起搏器的感知功能及起搏功能，对促进患康复、杜绝术后并发症起到重要作用。7例患双心室起搏治疗成功，心功能明显改善，生活可自理。     

Inhibition of biventricular pacing by far-field left atrial activity sensing: case report

This case report describes a patient with biventricular pacemaker in whom a far-field sensing of left atrial activity by the pacemaker's ventricular channel resulted in ventricular pacing inhibition. Placing of the left ventricular pacing electrode in the proximal part of the coronary sinus tributary resulted in this far-field sensing problem, which was resolved following decreasing the ventricular sensitivity. The authors suggest that the far-field sensing of the left atrial activity should be kept in mind for troubleshooting of an atrio-biventricular pacing system.     

Implantation of a biventricular pacing system in a patient with a coronary sinus not communicating with the right atrium

Intubation of the coronary sinus failed during implantation of a biventricular pacing system. An angiogram of the left coronary artery showed in the venous phase a coronary sinus not communicating with the right atrium. The coronary sinus was draining into a persistent left superior vena cava communicating with the left subclavian vein. The coronary sinus lead was successfully implanted through the persistent left superior vena cava, whereas the atrial and ventricular leads were implanted through the right superior vena cava in a conventional way.     

Latency during left ventricular pacing from the lateral cardiac veins: a cause of ineffectual biventricular pacing

We report three patients with cardiomyopathy and pronounced stimulus to QRS latency during left ventricular (LV) pacing from an epicardial cardiac vein. Delayed LV activation during simultaneous biventricular pacing produced an electrocardiographic pattern dominated by right ventricular stimulation. Hemodynamic parameters improved immediately after advancing LV stimulation (in one patient) or pacing the LV only (in two patients) coupled with dramatic improvement of heart failure symptoms.     

Economic analysis of a randomized trial of biventricular pacing in Canada

BACKGROUND: Congestive heart failure (CHF) has been shown to affect 5% of the Canadian adult population, and leads to 9.5 deaths per 100 cardiac-related hospitalizations in Canada. The economic outcomes from biventricular pacing for heart failure are not well understood. This study analyzes resource utilization and related costs associated with CHF for patients who receive standard implantable cardiac defibrillators (ICDs) versus those who receive ICD plus biventricular pacing or cardiac resynchronization therapy (CRT). METHODS: The Canadian analysis of resynchronization therapy in heart failure (CART-HF) study included 72 patients with New York Heart Association class II-IV CHF requiring an ICD. Patients were randomized to receive either ICD + CRT treatment or ICD treatment alone. Medical resource utilization data were collected for 6 months following treatment and were applied to representative costs for the provinces of Quebec and Ontario. Resource utilization was subcategorized into pharmacological therapy, physician visits, hospitalizations, adverse events, and productivity losses. RESULTS: Post-treatment, per patient costs for the CRT + ICD treatment group were less than the follow-up costs for patients receiving ICD treatment only in each province. Mean savings for patients receiving biventricular therapy were CAD 2,420 dollars in Quebec and CAD 2,085 dollars in Ontario during the 6-month follow-up. CONCLUSIONS: These analyses indicate that savings in post-implant health-care utilization (hospitalizations and pharmacological therapy) can offset some of the device and procedural costs associated with CRT devices.