Cliff Bucknall

Cardiac resynchronization therapy in advanced heart failure the multicenter InSync clinical study.

recent short‐term observations have shown an improvement in cardiac function and heart failure symptoms from atrio‐biventricular pacing. This study was designed to assess the safety and feasibility of an atrio‐biventricular transvenous pacing system, and examine the long‐term effects of cardiac resynchronization in patients with advanced heart failure and ventricular conduction abnormalities.

Non-contact left ventricular endocardial mapping in cardiac resynchronisation therapy

Background: Up to 30% of patients with heart failure do not respond to cardiac resynchronisation therapy (CRT). This may reflect placement of the coronary sinus lead in regions of slow conduction despite optimal positioning on current criteria. Objectives: To characterise the effect of CRT on left ventricular activation using non-contact mapping and to examine the electrophysiological factors influencing optimal left ventricular lead placement. Methods and results: 10 patients implanted with biventricular pacemakers were studied. In six, the coronary sinus lead was found to be positioned in a region of slow conduction with an average conduction velocity of 0.4 m/s, v 1.8 m/s in normal regions (p < 0.02). Biventricular pacing with the left ventricle paced 32 ms before the right induced the optimal mean velocity time integral and timing for fusion of depolarisation wavefronts from the right and left ventricular pacing sites. Pacing outside regions of slow conduction decreased left ventricular activation time and increased cardiac output and dP/dtmax significantly. Conclusions: In patients undergoing CRT for heart failure, non-contact mapping can identify regions of slow conduction. Significant haemodynamic improvements can occur when the site of left ventricular pacing is outside these slow conduction areas. Failure of CRT to produce clinical benefits may reflect left ventricular lead placement in regions of slow conduction which can be overcome by pacing in more normally activating regions.

Is Mode Switching Beneficial? A Randomized Study in Patients With Paroxysmal Atrial Tachyarrhythmias☆

OBJECTIVES We sought 1) to compare three pacing modalities-DDDR with mode switching (DM), DDDR with conventional upper rate behavior (DR) and VVIR (VR)-in patients with a history of atrial tachyarrhythmias, and 2) to assess the efficacy of six mode-switching algorithms. BACKGROUND A history of atrial tachyarrhythmias has been a relative contraindication to dual-chamber pacing. Several mode-switching algorithms have recently been developed to prevent rapid tracking of atrial tachyarrhythmias. METHODS Forty-eight patients (mean age 64 years, 58% male) with a history of atrial tachyarrhythmias and heart block had a DM pacemaker implanted. Pacemakers were programmed to DM, DR and VR modes for 4 weeks each in a randomized crossover design. All subjects used a patient-activated electrocardiographic (ECG) recorder throughout the study and additionally underwent ambulatory ECG monitoring and a treadmill exercise test in each mode. They completed three symptom questionnaires at the end of each pacing period. At the end of the study, patients chose their preferred pacing period. RESULTS DM was significantly better than VR mode objectively (exercise time DM 8.1 min, VR 7.0 min, p < 0.01) and subjectively (perceived well-being DM 69, VR 51, p < 0.001; functional class DM 2.2, VR 2.5, p < 0.05; subjective symptom score DM 21.2, VR 26.8, p = 0.01). Patient-perceived well-being was significantly better with DM than with DR mode (DM 69, DR 60, p = 0.02). DM mode was the preferred pacing period (DM 51%, DR 14%, VR 14%). Early termination of pacing because of adverse symptoms was requested by 33% of patients during VR, 19% during DR but only 3% during DM mode. A higher proportion of patients with a fast mode-switching device preferred DM mode (fast 55%, slow 49%), whereas no patients with a fast mode-switching device chose VR as the preferred mode (fast 0%, slow 19%). In the subgroup of patients who had had atrioventricular node ablation, DM was also preferred to VR mode (DM 53%, VR 27%). Overall, there were only two cases of inappropriate mode switching and one case of inappropriate tracking of an atrial tachyarrhythmia. CONCLUSIONS DM is the pacing mode of choice of patients with paroxysmal atrial tachyarrhythmias. With optimal programming, inappropriate mode switching and tracking of atrial tachyarrhythmias was very uncommon.

A Simultaneous X-Ray/MRI and Noncontact Mapping Study of the Acute Hemodynamic Effect of Left Ventricular Endocardial and Epicardial Cardiac Resynchronization Therapy in Humans

Background—Cardiac resynchronization therapy (CRT) using endocardial left ventricular (LV) pacing may be superior to conventional CRT. We studied the acute hemodynamic response to conventional CRT and LV pacing from different endocardial sites using a combined cardiac MRI and LV noncontact mapping (NCM) protocol to gain insights into the underlying mechanisms. Methods and Results—Fifteen patients (age, 63±10 years; 12 men) awaiting CRT were studied in a combined x-ray and MRI laboratory. Delayed-enhancement cardiac magnetic resonance was performed to define areas of myocardial fibrosis. Patients underwent an electrophysiological study incorporating endocardial and epicardial LV pacing. Acute hemodynamic response was measured using a pressure wire within the LV cavity to derive LV dP/dt max. NCM was used to define areas of slow conduction. There was a significant improvement in all LV pacing modes versus baseline (P<0.001). LV endocardial CRT from the best endocardial site was superior to conventional CRT, with a 79.8±49.0% versus 59.6±49.5% increase in LV dP/dt max of from baseline (P<0.05). The hemodynamic benefits of pacing were greater when LV stimulation was performed outside of areas of slow conduction defined by NCM (P<0.001). Delayed-enhancement cardiac magnetic resonance was able to delineate zones of slow conduction seen with NCM in ischemic patients but was unreliable in nonischemic patients. Conclusions—Endocardial LV pacing appears superior to conventional CRT, although the optimal site varies between subjects and is influenced by pacing within areas of slow conduction. Delayed-enhancement cardiac magnetic resonance was a poor predictor of zones of slow conduction in nonischemic patients.

Benefits of endocardial and multisite pacing are dependent on the type of left ventricular electric activation pattern and presence of ischemic heart disease: insights from electroanatomic mapping.

Background—There is considerable heterogeneity in the myocardial substrate of patients undergoing cardiac resynchronization therapy (CRT), in particular in the etiology of heart failure and in the location of conduction block within the heart. This may account for variability in response to CRT. New approaches, including endocardial and multisite left ventricular (LV) stimulation, may improve CRT response. We sought to evaluate these approaches using noncontact mapping to understand the underlying mechanisms. Methods and Results—Ten patients (8 men and 2 women; mean [SD] age 63 [12] years; LV ejection fraction 246%; QRS duration 161 [24] ms) fulfilling conventional CRT criteria underwent an electrophysiological study, with assessment of acute hemodynamic response to conventional CRT as well as LV endocardial and multisite pacing. LV activation pattern was assessed using noncontact mapping. LV endocardial pacing gave a superior acute hemodynamic response compared with conventional CRT (26% versus 37% increase in LV dP/dtmax, respectively; P<0.0005). There was a trend toward further incremental benefit from multisite LV stimulation, although this did not reach statistical significance (P=0.08). The majority (71%) of patients with nonischemic heart failure etiology or functional block responded to conventional CRT, whereas those with myocardial scar or absence of functional block often required endocardial or multisite pacing to achieve CRT response. Conclusions—Endocardial or multisite pacing may be required in certain subsets of patients undergoing CRT. Patients with ischemic cardiomyopathy and those with narrower QRS, in particular, may stand to benefit.

Pacemaker and Defibrillator Lead Extraction: Predictors of Mortality during Follow‐Up

Background: Extraction of cardiac implantable electric devices is an accepted procedure when systems become infected or malfunction. However, there is an associated morbidity and mortality. We report our 5‐year experience and identify predictors of mortality, and long‐term follow‐up.

Extraction of chronic pacemaker and defibrillator leads from the coronary sinus: laser infrequently used but required

AIMS Cardiac resynchronization therapy is an accepted treatment for heart failure but it may be necessary to explant these systems along with their leads. The evidence base for coronary sinus (CS) lead extractions is limited. We aimed to evaluate the percutaneous removal of these leads and the utility of laser extraction when necessary. METHODS AND RESULTS Of 265 patients referred for lead extraction between January 2004 and June 2008, 32 (12.1%) involved CS leads (30 males, mean age 67 years). Mean implantation time was 26.5 +/- 28.7 months (range 1-116 months). Indications for extraction were pocket infection (34.4%), lead malfunction (43.8%), skin erosion (15.6%), and endocarditis (6.2%). Twenty-eight (87.5%) CS leads were removed with manual traction, with laser utilized in four cases (12.5%). No major complications of CS laceration, pericardial effusion, emergency surgery, or death occurred. CONCLUSION Our experience supports the percutaneous extraction of CS leads as a safe and effective procedure including the utility of laser when necessary.

Trends, indications and outcomes of cardiac implantable device system extraction: a single UK centre experience over the last decade

Background:  The rising number of device implantation has seen a parallel in the rising numbers of lead extraction. Herein we have analysed our experience in cardiac device and lead extraction in a single tertiary centre over the last decade.

Laser lead extraction to facilitate cardiac implantable electronic device upgrade and revision in the presence of central venous obstruction

Aims The number of procedures involving upgrade or revision of cardiac implantable electronic devices (CIEDs) is increasing and the risks of adding additional leads are significant. Central venous occlusion in patients with pre-existing devices is often asymptomatic and optimal management of such patients in need of device revision/upgrade is not clear. We sought to assess our use of laser lead extraction in overcoming venous obstruction. Methods and results Patients in need of device upgrade/revision underwent pre-procedure venography to assess venous patency. In patients with venous occlusion or stenosis severe enough to preclude passage of a hydrophilic guide wire, laser lead extraction with retention of the outer sheath in the vasculature was performed with the aim of maintaining a patent channel through which new leads could be implanted. Data were recorded on a dedicated database and patient outcomes were assessed. Between July 2004 and April 2012, laser lead extractions were performed in 71 patients scheduled for device upgrade/revision who had occluded or functionally obstructed venous anatomy. New leads were successfully implanted across the obstruction in 67 (94%) cases. There were two major complications (infection) and four minor complications with no peri-procedural mortality. Device follow-up was satisfactory in 65 (92%) cases with mean follow-up up to 26 ± 19 months. Conclusion Laser lead extraction is a safe and effective option when managing patients with central venous obstruction in need of CIED revision or upgrade.

Percutaneous lead and system extraction in patients with cardiac resynchronization therapy (CRT) devices and coronary sinus leads.

Background:  Cardiac resynchronization therapy (CRT) device and coronary sinus (CS) lead extraction is required due to the occurrence of system infection, malfunction, or upgrade. Published series of CS lead extraction are limited by small sample sizes. We present a 10‐year experience of CRT device and CS lead extraction.