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.

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.

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.

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.

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.

Timing of the left ventricular electrogram and acute hemodynamic changes during implant of cardiac resynchronization therapy devices.

STUDY OBJECTIVE: To examine the relationship between timing of the left ventricular (LV) electrogram (EGM) and its acute hemodynamic effect on instantaneous change in LV pressure (LVdP/dt(MAX)). PATIENTS AND METHODS: In 30 patients (mean = age 67 +/- 7.9 years) who underwent implant of cardiac resynchronization therapy systems, the right ventricular (RV) lead was implanted at the RV apex (n = 23) or RV septum (n = 7). The LV lead was placed in a posterior (n = 14) or posterolateral (n = 16) coronary sinus tributary. QRS duration, interval from Q wave to intrinsic deflection of the LV EGM (Q-LV), and interval between intrinsic deflection of RV EGM and LV EGM (RV-LV interval) were measured. The measurements were correlated with the hemodynamic effects of optimized biventricular (BiV) stimulation, using the Pearson correlation coefficient. RESULTS: The mean LVdP/dt(MAX) at baseline was 734 +/- 180 mmHg/s, and increased to 905 +/- 165 mmHg/s during simultaneous BiV pacing, and to 933 +/- 172 mmHg/s after V-V interval optimization. The Pearson correlation coefficient R between QRS duration, the Q-LV interval, and the RV-LV interval at the respective LVdP/dt(MAX) was 0.291 (P = 0.66), 0.348 (P = 0.030), and 0.340 (P = 0.033). CONCLUSIONS: Similar significant correlations were observed between the acute hemodynamic effect of optimized BiV stimulation and the Q-LV and the RV-LV intervals. However, individual measurements showed an 80-ms cut-off for the Q-LV interval, beyond which the increase in LVdP/dt(MAX) was <10%.

Initiation of ventricular tachycardia by interruption of pacemaker-mediated tachycardia in a patient with a dual-chamber implantable cardioverter defibrillator.

A 74-year-old man with a dual-chamber implantable cardioverter defibrillator implanted 3 years before experienced multiple ventricular tachycardias (VTs). All episodes were initiated by pacemaker-mediated tachycardia (PMT) that was either stopped by atrial undersensing or the tachycardia termination algorithm of the device. After the termination of PMT, two rapid ventricular paced beats, the first initiated by artificial triggering and the second due to retrograde conduction of the first one, initiated VT that was successfully terminated by antitachycardia pacing or a direct current shock of the device. All episodes revealed this pattern of initiation with a short-long-short ventricular sequence inducing VT.

Acute hemodynamic effects of cardiac resynchronization therapy in patients with poor left ventricular function during cardiac surgery.

BACKGROUND: Cardiac resynchronization therapy improves systolic function in patients with heart failure and left ventricular (LV) dyssynchrony. However, the effect of biventricular (BiV) pacing on perioperative hemodynamics in cardiac surgery is not well known. We investigated the acute hemodynamic response using LVdP/dt(max) in patients with depressed LV function and conduction disturbances undergoing cardiac surgery. METHODS: Patients with LV ejection fraction of < or =35%, QRS duration of >130 ms, and left bundle branch block undergoing aortocoronary bypass and valve surgery were included. Temporary atrial and left and right ventricular pacing wires were applied, and LVdP/dt(max) was measured with a high fidelity pressure wire in the left ventricle at the end of cardiopulmonary bypass. Responders had a > or =10% increase in LVdP/dt(max). RESULTS: Eleven patients (age 63 +/- 11 years, eight males) with a LV ejection fraction 0.29 +/- 0.06% were included. Compared with right ventricular pacing (782 +/- 153 mmHg/sec), there was a significant improvement in the mean LVdP/dt(max) during simultaneous BiV pacing (849 +/- 174 mmHg/sec; p = 0.034) and sequential BiV pacing with the LV 40 ms advanced (880 +/- 157 mmHg/sec; p = 0.003). Improvement during LV pacing alone was not significant (811 +/- 141 mmHg/sec). Six patients were responders with simultaneous and nine with sequential BiV pacing. Only sequential BiV pacing had a significant improvement in LV systolic pressure (p = 0.02). CONCLUSIONS: BiV pacing results in acute hemodynamic improvement of LV function during cardiac surgery. Optimization of the interventricular pacing interval contributes to the effect of the therapy.

The optimized V-V interval determined by interventricular conduction times versus invasive measurement by LVdP/dtMAX.

INTRODUCTION: We compared the calculated optimal V-V interval derived from intracardiac electrograms (IEGM) with the optimized V-V interval determined by invasive measurement of LVdP/dt(MAX). METHODS AND RESULTS: Thirty-two patients with heart failure (six females, ages 68 +/- 7.8 years) had a CRT device implanted. After implantation of the atrial, right and a left ventricular lead, the optimal V-V interval was calculated using the QuickOpt formula (St. Jude Medical, Sylmar, CA, USA) applied to the respective IEGM recordings (V-V(IEGM)), and also determined by invasive measurement of LVdP/dt(MAX) (V-V(dP/dt)). The optimal V-V(IEGM) and V-V(dP/dt) intervals were 52.7 +/- 18 ms and 24.0 +/- 33 ms, respectively (P = 0.017), without correlation between the two. The baseline LVdP/dt(MAX) was 748 +/- 191 mmHg/s. The mean value of LVdP/dt(MAX) at invasive optimization was 947 +/- 198 mmHg/s, and at the calculated optimal V-V(IEGM) interval 920 +/- 191 mmHg/s (P < 0.0001). In spite of this significant difference, there was a good correlation between both methods (R = 0.991, P < 0.0001). However, a similarly good correlation existed between the maximum value of LVdP/dt(MAX) and LVdP/dt(MAX) at a fixed V-V interval of 0 ms (R = 0.993, P < 0.0001), or LVdP/dt(MAX) at a randomly selected V-V interval between 0 and +80 ms (R = 0.991, P < 0.0001). CONCLUSION: Optimizing the V-V interval with the IEGM method does not yield better hemodynamic results than simultaneous BiV pacing. Although a good correlation between LVdP/dt(MAX) determined with V-V(IEGM) and V-V(dP/dt) can be constructed, there is no correlation with the optimal settings of V-V interval in the individual patient.

Coronary sinus atresia and persistent left superior vena cava with the presence of thrombus complicating implantation of a left ventricular pacing lead.

A 68-year-old male with heart failure and a suitable candidate for resynchronization therapy was referred to our hospital because of a failed coronary sinus (CS) lead implant. Catheterization of the CS initially also failed in our department but a left coronary angiogram revealed atresia of the CS and drainage of the coronary venous system via a persistent left superior vena cava (PLSVC). Implantation of a CS lead through the PLSVC could be accomplished after a selective angiogram, even in spite of the presence of a large thrombus at the junction of PLSVC and CS.

The ECG lead I paradox in cardiac resynchronization therapy.

BACKGROUND: In cardiac resynchronization therapy (CRT), the morphology of the QRS complex plays an important role in the determination of the pacing site and effectiveness of stimulation. PATIENTS AND METHODS: Review of the electrocardiograms (ECGs) of 737 patients with a CRT device showed a negative QRS complex in lead I during right ventricular (RV) pacing and a positive QRS complex during left ventricular (LV) pacing in four patients. The RV lead was positioned in the high RV septum and the coronary sinus leads in a posterior or postero-lateral basal level. Reversed ECG lead or pacemaker lead connection, anodal RV stimulation, and scar tissue-related depolarization abnormalities were excluded as possible causes. CONCLUSION: Pacing from the high RV septum may rarely lead to a negative QRS complex and basal positions of the LV lead to a positive QRS complex in lead I during LV pacing. The lead I paradox becomes obvious when both phenomena, that are not interrelated, are present in the same patient.

Stimulation rate and the optimal interventricular interval during cardiac resynchronization therapy in patients with chronic atrial fibrillation.

BACKGROUND: Optimization of cardiac resynchronization therapy (CRT) with respect to the interventricular (V-V) interval is mainly limited to pacing at a resting heart rate. We studied the effect of higher stimulation rates with univentricular and biventricular (BiV) pacing modes including the effect of the V-V interval optimization. METHODS: In 36 patients with heart failure and chronic atrial fibrillation (AF), the effects of right ventricular (RV), left ventricular (LV), simultaneous BiV, and optimized sequential BiV (BiVopt) pacing were measured. The effect of the pacing mode and the optimal V-V interval was determined at stimulation rates of 70, 90, and 110 ppm using invasive measurement of the maximum rate of left ventricular pressure rise (LV dP/dt(max)). RESULTS: The average LV dP/dt (max) for all pacing modalities at stimulation rates of 70, 90, and 110 ppm was 781 +/- 176, 833 +/- 197, and 884 +/- 223 mmHg/s for RV pacing; 893 +/- 178, 942 +/- 186, and 981 +/- 194 mmHg/s for LV pacing; 904 +/- 179, 973 +/- 187, and 1052 +/- 206 mmHg/s for simultaneous BiV pacing; and 941 +/- 186, 1010 +/- 198, and 1081 +/- 206 mmHg/s for BiVopt pacing, respectively. In BiVopt pacing, the corresponding optimal V-V interval decreased from 34 +/- 29, 28 +/- 28, and21 +/- 27ms at stimulation rates of 70, 90, and 110 ppm, respectively. In two individuals, LV dP/dt(max) decreased when the pacing rate was increased from 90 to 110 ppm. CONCLUSION: In patients with AF and heart failure, LV dP/dt(max) increases for all pacing modalities at increasing stimulation rates in most, but not all, patients. The rise in LV dP/dt(max) with increasing stimulation rates is higher in biventricular (BiV and BiVopt) than in univentricular (LV and RV) pacing. The optimal V-V interval at sequential biventricular pacing decreases with increasing stimulation rates.

Transseptal endocardial left ventricular pacing: an alternative technique for coronary sinus lead placement in cardiac resynchronization therapy.

BACKGROUND: Coronary sinus (CS) lead placement for transvenous left ventricular (LV) pacing in cardiac resynchronization therapy (CRT) has a failure rate at implant and short-term follow-up between 10% and 15%. OBJECTIVE: The purpose of this study was to assess the feasibility of transseptal endocardial LV pacing in patients in whom transvenous CS lead placement had failed. METHODS: An atrial transseptal LV lead placement was attempted in 10 patients (six females, age 69.4 +/- 9.6 years), in whom CS lead placement for CRT had failed. After transseptal puncture and septal dilatation from the femoral route, the left atrium was cannulated with a combination of catheters and guide wires from the left or right subclavian vein. After advancement of this guide catheter into the LV, a standard bipolar screw-in lead could be implanted in the posterolateral wall. All patients were maintained on anticoagulant therapy with warfarin after implant. RESULTS: An LV lead could be successfully implanted in nine of the 10 patients. The stimulation threshold was 0.78 +/- 0.24 V, and the R-wave amplitude was 14.2 +/- 9.7 mV. At 2 months' follow-up, the stimulation threshold was 1.48 +/- 0.35 V with a 0.064 +/- 0.027 ms pulse width. There was no phrenic nerve stimulation observed in any of the patients. There were no thromboembolic complications at follow-up. CONCLUSIONS: LV transseptal endocardial lead implantation from the pectoral area is a feasible approach in patients with a failed CS approach and in whom epicardial surgical lead placement is not an option. Longer follow-up is warranted to determine the risk of thromboembolic complications.

Correlation of echo-Doppler optimization of atrioventricular delay in cardiac resynchronization therapy with invasive hemodynamics in patients with heart failure secondary to ischemic or idiopathic dilated cardiomyopathy.

This study investigated the optimal echocardiographic indexes to determine the most hemodynamically appropriate atrioventricular (AV) delay in cardiac resynchronization therapy (CRT) for heart failure. Doppler echocardiographic optimization of AV delay in CRT has not been correlated with invasive hemodynamic indexes. In 30 patients who underwent CRT, invasive left ventricular (LV) pressure measurements with a sensor-tipped pressure guidewire and Doppler echocardiographic examination were performed <24 hours after pacemaker implantation. Invasively, the optimal sensed AV delay was determined by LV dP/dt(max). The Doppler echocardiographic methods evaluated were the velocity-time integral (VTI) of the transmitral flow (EA VTI), diastolic filling time (EA duration), the VTI of the LV outflow tract or aorta (LV VTI), and Ritter's formula. Biventricular pacing with optimized interventricular and AV delay increased LV dP/dt(max) from 777 +/- 149 to 1,010 +/- 163 dynes/s (p<0.0001). The optimal AV delay with the EA VTI method was concordant with LV dP/dt(max) in 29 of 30 patients (r = 0.96), with EA duration in 20 of 30 patients (r= 0.83), with LV VTI in 13 patients (r = 0.54), and with Ritter's formula in none of the patients (r = 0.35). In conclusion, to obtain the optimal acute hemodynamic benefit of CRT, Doppler echocardiography is a reliable tool to optimize the AV delay compared with the invasive LV dP/dt(max). The measurement of the maximal VTI of mitral inflow is the most accurate method.

Paradoxical atrial undersensing: noise rate reversion or amplifier ringing?

Atrial tachy-arrhythmias may give rise to mode switching or noise rate reversion in dual-chamber pacemakers. In case of high amplitude of the atrial electrogram during tachycardia, a paradoxical behavior of atrial sensitivity programming can be observed. Two patients with implanted dual-chamber pacemakers showed intermittent and complete loss of atrial sensing during atrial tachycardia during device programming to a higher atrial sensitivity setting. This phenomenon is caused by amplifier ringing and can be considered as a state of amplifier saturation, which disables atrial sensing in spite of the high amplitude of the atrial signal. In patients with high amplitude of the atrial electrogram during atrial tachycardia, a paradoxical behavior of sensitivity programming resulting in atrial undersensing can be observed.