Electrical latency predicts the optimal left ventricular endocardial pacing site: results from a multicentre international registry.

Aims: The optimal site for biventricular endocardial (BIVENDO) pacing remains undefined. Acute haemodynamic response (AHR) is reproducible marker of left ventricular (LV) contractility, best expressed as the change in the maximum rate of LV pressure (LV-dp/dtmax), from a baseline state. We examined the relationship between factors known to impact LV contractility, whilst delivering BIVENDO pacing at a variety of LV endocardial (LVENDO) locations. Methods and results: We compiled a registry of acute LVENDO pacing studies from five international centres: Johns Hopkins-USA, Bordeaux-France, Eindhoven-The Netherlands, Oxford-United Kingdom, and Guys and St Thomas' NHS Foundation Trust, London-UK. In all, 104 patients incorporating 687 endocardial and 93 epicardial pacing locations were studied. Mean age was 66 ± 11 years, mean left ventricular ejection fraction 24.6 ± 7.7% and mean QRS duration of 163 ± 30 ms. In all, 50% were ischaemic [ischaemic cardiomyopathy (ICM)]. Scarred segments were associated with worse haemodynamics (dp/dtmax; 890 mmHg/s vs. 982 mmHg/s, P < 0.01). Delivering BiVENDO pacing in areas of electrical latency was associated with greater improvements in AHR (P < 0.01). Stimulating late activating tissue (LVLED >50%) achieved greater increases in AHR than non-late activating tissue (LVLED < 50%) (8.6 ± 9.6% vs. 16.1 ± 16.2%, P = 0.002). However, the LVENDO pacing location with the latest Q-LV, was associated with the optimal AHR in just 62% of cases. Conclusions: Identifying viable LVENDO tissue which displays late electrical activation is crucial to identifying the optimal BiVENDO pacing site. Stimulating late activating tissue (LVLED >50%) yields greater improvements in AHR however, the optimal location is frequently not the site of latest activation.

Late asymptomatic atrial lead perforation, a fortuitous finding during lead extraction using thoracoscopic surveillance: a case report and review of the literature.

A 61-year-old male patient was referred for lead extraction of an infected two-chamber pacemaker system first implanted 18 years ago. A new atrial lead was implanted 9 years later because of loss of capture of the original lead. Video-assisted thoracoscopic surgery (VATS) that we use in high-risk cases showed extensive fibrous adhesion between the right atrium wall and the right lung. Dissection of the adhesion revealed the presence of an atrial lead perforated into the lung. After cutting off the lead tip, the residual lead was removed endovascularly from the subclavian site. A literature review of 25 reported cases of late atrial lead perforation was added to the findings in our case report.

Acute hemodynamic effects of single- and dual-site left ventricular pacing employing a dual cathodal coronary sinus lead.

BACKGROUND: We studied the acute hemodynamic effect of left ventricular (LV) pacing from a dual cathodal coronary sinus (CS) lead in a both single- and dual-site electrode configuration. METHODS: In 17 patients who underwent implantation of a cardiac resynchronization therapy-defibrillator system with dual cathodal CS leads, LV stimulation was performed from the distal and proximal electrode separately and from both electrodes simultaneously. The acute hemodynamic response was evaluated by invasive measurement of LVdP/dtmax. Timing of LV electrical activation time measured from onset QRS to LV sense during intrinsic rhythm at both electrodes were determined from simultaneous intracardiac recordings. The latter results were compared to those of an additional group of 26 patients in whom no hemodynamic effects were evaluated. RESULTS: Baseline LVdP/dtmax was 897 ± 222 mm Hg/s. Single-site LV pacing resulted in a rise of LVdP/dtmax to 1,053 ± 266 mm Hg/s (+17.4%) taking the best of the two sites and 1,020 ± 254 mm Hg (+13.7%) at the worst site (P = 0.0001). In the dual-site pacing configuration LVdP/dtmax was 1,026 ± 243 mm Hg/s (+14.1%). P value for single best versus dual site was 0.005, and for dual site versus worst single site was 0.18 (n.s.). CONCLUSION: Even with a relatively small distance of 20-21 mm between stimulation electrodes, there is a significant difference in acute hemodynamic effect from the single best and worst site. Dual-site LV pacing offers no hemodynamic benefit over the best single pacing site. The short electrode distance may have been a limitation and results may not be applicable to other forms of multisite pacing.

Mid-term follow up of thromboembolic complications in left ventricular endocardial cardiac resynchronization therapy.

BACKGROUND: Endocardial left ventricular (LV) pacing for cardiac resynchronization therapy (CRT) has been proposed as an alternative to traditional LV transvenous epicardial pacing with equal or superior cardiac performance. The risks of cerebral thromboembolism and possible interference with mitral valve function moderate its clinical application. OBJECTIVE: The purpose of this study was to investigate cerebral thromboembolic complications after LV endocardial lead placement. Mitral regurgitation (MR) was the secondary outcome measure. METHODS: CRT candidates with a failed coronary sinus approach or nonresponders to conventional CRT underwent endocardial LV lead implantation (45 atrial transseptal, 6 transapical). Coumarin was prescribed with a targeted international normalized ratio between 3.5 and 4.5. Patient records were checked and general practitioners were contacted regarding cerebral thromboembolic complications. MR was evaluated by echocardiography at baseline and after 6 months. RESULTS: In 7 patients, 6 ischemic strokes and 2 transient ischemic attacks occurred, corresponding to 6.1 thromboembolic events per 100 patient-years (95% confidence interval 3.4-15.8). One patient refused hospital admission; all other patients had a subtherapeutic anticoagulation level at the time of the event. No major bleeding complications occurred. There was no change in the grade of MR (grade 2, P = .727) after 6 months. CONCLUSION: Endocardial LV lead placement in patients with advanced heart failure is associated with thromboembolic risk. However, all but 1 patient had a subtherapeutic level of anticoagulation. Endocardial LV lead placement is not associated with aggravation of MR.

Cardiac resynchronisation therapy optimisation strategies: systematic classification, detailed analysis, minimum standards and a roadmap for development and testing.

In this article an international group of CRT specialists presents a comprehensive classification system for present and future schemes for optimising CRT. This system is neutral to the measurement technology used, but focuses on little-discussed quantitative physiological requirements. We then present a rational roadmap for reliable cost-effective development and evaluation of schemes. A widely recommended approach for AV optimisation is to visually select the ideal pattern of transmitral Doppler flow. Alternatively, one could measure a variable (such as Doppler velocity time integral) and "pick the highest". More complex would be to make measurements across a range of settings and "fit a curve". In this report we provide clinicians with a critical approach to address any recommendations presented to them, as they may be many, indistinct and conflicting. We present a neutral scientific analysis of each scheme, and equip the reader with simple tools for critical evaluation. Optimisation protocols should deliver: (a) singularity, with only one region of optimality rather than several; (b) blinded test-retest reproducibility; (c) plausibility; (d) concordance between independent methods; and (e) transparency, with all steps open to scrutiny. This simple information is still not available for many optimisation schemes. Clinicians developing the habit of asking about each property in turn will find it easier to win now down the broad range of protocols currently promoted. Expectation of a sophisticated enquiry from the clinical community will encourage optimisation protocol-designers to focus on testing early (and cheaply) the basic properties that are vital for any chance of long term efficacy.

The Needle's Eye Snare as a primary tool for pacing lead extraction.

AIMS: The femoral approach for lead extraction is typically used as a bailout procedure. We describe the results of a femoral approach with a Needle's Eye Snare and Femoral Workstation as a primary tool for extracting pacing leads. PATIENTS AND METHODS AND RESULTS: Four hundred and seventy-six pacing leads implanted for >6 months were extracted in 229 consecutive patients (178 male, age 70.4 ± 12.7 years). First, traction was performed with a standard stylet, and if unsuccessful this was followed by the femoral approach with a Needle's Eye Snare. Traction sufficed for 136 leads and a femoral approach was required in 340 leads, their respective implant times were 3.7 ± 2.9 and 9.2 ± 5.8 years. The Needle's Eye Snare failed or was only partial successful (leaving a lead remnant of <4 cm) in, respectively, 1.8 and 3.8% of all leads, 2.7 and 7.1% of 182 right ventricular, 0.7 and 0% of 144 atrial leads, and in none of 14 coronary sinus leads. All leads implanted for <10 years were removed with a clinical success. Two patients were successfully operated after pericardial tamponade. There were no procedure-related deaths. CONCLUSION: Needle's Eye Snare lead extraction has a low complication rate. The technique should be considered as a primary tool for extraction of pacing leads, particularly atrial and coronary sinus pacing leads. The results for extracting ventricular leads might be improved if larger bore sheaths with a better cutting edge were available.

Baseline left ventricular dP/dtmax rather than the acute improvement in dP/dtmax predicts clinical outcome in patients with cardiac resynchronization therapy.

AIMS: The maximum rate of left ventricular (LV) pressure rise (dP/dt(max)) has been used to assess the acute haemodynamic effect of cardiac resynchronization therapy (CRT). We tested the hypothesis that LV dP/dt(max) predicts long-term clinical outcome after initiation of CRT. METHODS AND RESULTS: This was a retrospective observational multicentre study in 285 patients in whom dP/dt(max) was measured invasively following implantation of a CRT device. The minimum required follow-up was 1 year. We analysed the relationship between dP/dt(max) and time to the composite endpoint, consisting of all-cause mortality, heart transplantation (HTX), or LV assist device (LVAD) implantation within the first year of CRT. Thirty-four events occurred after a mean follow-up of 160 days (range 21-359). Patients with an event had lower dP/dt(max) than patients without an event both at baseline (705 ± 194 vs. 800 ± 222 mmHg/s, P= 0.018) and during CRT (894 ± 224 vs. 985 ± 244 mmHg/s, P= 0.033), but the acute increase in dP/dt(max) was similar in patients with and without an event (190 ± 133 vs. 185 ± 115 mmHg/s, P= n.s.). Left ventricular dP/dt(max)-level at baseline and during CRT both predicted the clinical outcome after adjustment for gender, aetiology and New York Heart Association class: hazard ratio (HR) 0.791 [95% confidence interval (CI) 0.658-0.950, P= 0.012] and HR 0.846 (95% CI 0.723-0.991, P= 0.038), respectively. CONCLUSION: Left ventricular dP/dt(max) measured at baseline and during CRT are predictors of 1-year survival free from all-cause mortality, HTX, or LVAD implantation, but the acute improvement in dP/dt(max) is not correlated to clinical outcome.

Transseptal left ventricular endocardial pacing: preliminary experience from a femoral approach with subclavian pull-through.

AIMS: Coronary sinus (CS) lead placement for transvenous cardiac resynchronization therapy (CRT) even combined with transseptal left ventricular (LV) endocardial implantation from a superior approach still does not have 100% success rate. The aim of this study was to assess the feasibility of a femoral transseptal endocardial LV approach pacing in patients in whom a transvenous CS or a transseptal LV endocardial implantation with a superior approach had failed. We report our first experience with LV endocardial lead placement for CRT with a femoral transseptal technique followed by intravascular pull-through to the pectoral location. METHODS AND RESULTS: In 11 patients, 10 males (61.5 ± 9.5 years) with failed CS implant (four patients) or repeated CS lead malfunction (seven patients), a 4.1 French active fixation lead was implanted endocardially in the left ventricle employing a femoral approach using an 8F transseptal sheath combined with a hooked 6F catheter. After successful implantation, the lead was pulled through from the femoral insertion site to the pectoral device location. The LV endocardial implantation was successfully performed in all patients. Stimulation threshold was 0.62 ± 0.33 V, lead impedance 825 ± 127 Ω, and R wave 12.8 ± 8.3 mV. Threshold and lead impedance were stable during follow-up, which varied from 1 to 6 months. No dislodgements were observed and there were no thrombo-embolic events during follow-up. CONCLUSION: This technique for LV endocardial lead implantation is an alternative for failed CS and superior transseptal attempts using standard techniques and equipment. It is also applicable for pacing sites that are more easily reached from a femoral approach.

Atrioventricular and interventricular delay optimization in cardiac resynchronization therapy: physiological principles and overview of available methods.

In this review, the physiological rationale for atrioventricular and interventricular delay optimization of cardiac resynchronization therapy is discussed including the influence of exercise and long-term cardiac resynchronization therapy. The broad spectrum of both invasive and non-invasive optimization methods is reviewed with critical appraisal of the literature. Although the spectrum of both invasive and non-invasive optimization methods is broad, no single method can be recommend for standard practice as large-scale studies using hard endpoints are lacking. Current efforts mainly investigate optimization during resting conditions; however, there is a need to develop automated algorithms to implement dynamic optimization in order to adapt to physiological alterations during exercise and after anatomical remodeling.

Atrioventricular Cross-Talk Leading to Ventricular Pacing Inhibition in a Dual-Chamber ICD.

We report atrio-ventricular cross talk in a patient with a dual chamber ICD leading to ventricular pacing inhibition. This was observed in an ICD without the ventricular safety pace option, which normally is a sufficient protection against this phenomenon. Cross talk could be prevented effectively by reprogramming ventricular sensitivity to a less sensitive setting.

Increase of ventricular output inducing ventricular afterpotential sensing and ventricular safety pacing in a biventricular implanted cardioverter defibrillator.

Programming maximum right ventricular output in a patient with a biventricular implanted cardioverter defibrillator resulted in ventricular oversensing and ventricular safety pacing in the same cardiac cycle.