Philippe Ritter

Acute hemodynamic effects of biventricular DDD pacing in patients with end-stage heart failure

OBJECTIVES The aim of this study was to assess the potential acute benefit of multisite cardiac pacing with optimized atrioventricular synchrony and simultaneous biventricular pacing in patients with drug-refractory congestive heart failure (CHF). BACKGROUND Prognosis and quality of life in severe CHF are poor. Various nonpharmacological therapies have been evaluated but are restricted in their effectiveness and applications. In the early 1990s, dual chamber pacing (DDD) pacing was proposed as primary treatment of refractory CHF but results were controversial. Recently, tests to evaluate the effect of simultaneous pacing of both ventricles have elicited a significant improvement of cardiac performance. METHODS Acute hemodynamic study was conducted in 18 patients with severe CHF (New York Heart Association class III and IV) and major intraventricular conduction block (IVCB) (QRS duration = 170+/-37 ms). Using a Swan-Ganz catheter, pulmonary artery pressure, pulmonary capillary wedge pressure (PCWP) and cardiac index (CI) were measured in different pacing configurations: atrial pacing (AAI) mode, used as reference, single-site right ventricular DDD pacing and biventricular pacing with the right ventricular lead placed either at the apex or at the outflow tract. RESULTS The CI was significantly increased by biventricular pacing in comparison with AAI or right ventricular (RV). DDD pacing (2.7+/-0.7 vs. 2+/-0.5 and 2.4+/-0.6 l/min/m2, p < 0.001). The PCWP also decreased significantly during biventricular pacing, compared with AAI (22+/-8 vs. 27+/-9 mm Hg; p < 0.001). CONCLUSIONS This acute hemodynamic study demonstrated that biventricular DDD pacing may significantly improve cardiac performance in patients with IVCB and with severe heart failure, in comparison with intrinsic conduction and single-site RV DDD pacing.

Four chamber pacing in dilated cardiomyopathy

A 54‐year‐old man received a four chamber pacing system for severe congestive heart failure (NYHA functional Class IV). His ECG showed a left bundle branch block (200‐msec QHS duration) with 200‐msec PR interval, normal QRS axis, and 90‐msec interatrial interval. An acute hemodynamic study with insertion of four temporary leads was performed prior to the implant, which demonstrated a significant increase in cardiac output and decrease of pulmonary capillary wedge pressure. A permanent pacemaker was implanted based on the encouraging results of the acute study. The right chamber leads were introduced by cephalic and suhcla vian approaches. The left atrium was paced with a coronary sinus lead, Medtronic SP 2188–58 model. An epicardial Medtronic 5071 lead was placed on the LV free wall. The four leads were connected to a standard bipolar DDD pacemaker. Chorus 6234. The two atrial leads were connected via a Y‐connector to the atrial channel of the pacemaker with a bipolar pacing configuration. The two ventricular leads were connected in a similar fashion to the ventricular channel of the device. The right chamber leads were connected to the distal poles. The left chamber leads were connected to the proximal poles of the pacemaker. Six weeks later, the patients clinical status improved markedly with a weight loss of 17 kg and disappearance of peripheral edema. His functional class was reduced to NYHA II. Four chamber pacing is technically feasible. In patients with evidence of interventricular dyssynchrony, this original pacing mode probably provides a mechanical activation sequence closer to the natural one. We doubt that this technique will have an impact on long‐term survival, but it could be of major importance to improve the patients well‐being and control heart failure.

Multisite pacing for end-stage heart failure : early experience

Our objective was to improve hemodynamics by synchronous right and left site ventricular pacing in patients with severe congestive heart failure (CHF). Previous studies reported a benefit of dual chamber pacing with a short AV delay in patients with severe CHF. Other works, however, show contradictory results. Deleterious effects due to a desynchronization of right (RV) and left ventricular (LV) contractions have been suggested. This study included eight subjects with widened QRS and end‐stage heart failure despite maximal medical therapy, who refused, or were not eligible to undergo heart transplantation. Each patient underwent a baseline, invasive hemodynamic evaluation with insertion of three temporary leads to allow different pacing configurations, including RV apex and outflow tract pacing, and biventricular pacing between the RV outflow tract and LV and RV apex and LV. According to the results of this baseline study, the configuration of preexistent pacemakers was modified or new systems were implanted to allow biventricular pacing, which, in patients with sinus rhythm, was atrial triggered. Biventricular pacing increased the mean cardiac index (CI) by 25% (from a baseline of 1.83 ± 0.30 L/min per m2, P < 0.006), decreased the mean V wave by 26% (from a baseline of 36 ± 12 mmHg, P < 0.004), and decreased pulmonary capillary wedge pressure by 17% (from a baseline of 31 ± 10 mmHg, P < 0.01). Four patients died (1 preoperatively, 1 intraoperatively, 2 within 3 months, and 1 of a noncardiac cause). The four surviving patients have clinically improved from New York Heart Association Functional Class IV to Class II. In these survivors, CI decreased by 15% (P < 0.007) when multisite pacing was turned off during follow‐up. In patients with end‐stage heart failure, multisite pacing may be associated with a rapid and sustained hemodynamic improvement.

Outcome After Implantation of a Cardioverter-Defibrillator in Patients With Brugada Syndrome A Multicenter Study

Background— Implantable cardioverter-defibrillator indications in Brugada syndrome remain controversial, especially in asymptomatic patients. Previous outcome data are limited by relatively small numbers of patients or short follow-up durations. We report the outcome of patients with Brugada syndrome implanted with an implantable cardioverter-defibrillator in a large multicenter registry. Methods and Results— A total of 378 patients (310 male; age, 46±13 years) with a type 1 Brugada ECG pattern implanted with an implantable cardioverter-defibrillator (31 for aborted sudden cardiac arrest, 181 for syncope, and 166 asymptomatic) were included. Fifteen patients (4%) were lost to follow-up. During a mean follow-up of 77±42 months, 7 patients (2%) died (1 as a result of an inappropriate shock), and 46 patients (12%) had appropriate device therapy (5±5 shocks per patient). Appropriate device therapy rates at 10 years were 48% for patients whose implantable cardioverter-defibrillator indication was aborted sudden cardiac arrest, 19% for those whose indication was syncope, and 12% for the patients who were asymptomatic at implantation. At 10 years, rates of inappropriate shock and lead failure were 37% and 29%, respectively. Inappropriate shock occurred in 91 patients (24%; 4±4 shocks per patient) because of lead failure (n=38), supraventricular tachycardia (n=20), T-wave oversensing (n=14), or sinus tachycardia (n=12). Importantly, introduction of remote monitoring, programming a high single ventricular fibrillation zone (>210–220 bpm), and a long detection time were associated with a reduced risk of inappropriate shock. Conclusions— Appropriate therapies are more prevalent in symptomatic Brugada syndrome patients but are not insignificant in asymptomatic patients (1%/y). Optimal implantable cardioverter-defibrillator programming and follow-up dramatically reduce inappropriate shock. However, lead failure remains a major problem in this population.

Permanent Left Ventricular Pacing With Transvenous Leads Inserted Into The Coronary Veins

This paper describes a preliminary experiment ‐ conducted jointly by 2 centers ‐ of permanent left ventricular pacing using leads inserted by the transvenous route and through the coronary sinus into the cardiac veins of the left ventricle free wall. The aim was to obtain permanent biventricular pacing in a totally endocavitary configuration in pattents with severe LV dysfunction and drug‐refractory heart failure. Two types of leads were used: nonspecific unipolar leads at the beginning of the experiment, followed by leads specifically designed to be used in the coronary sinus in a second step. The electrode could be fitted in an adequate location in 35 of the 47 patients (75.4%), with a 1.15±0.7 V acute pactng threshold and 11.8±5.7 mV R wave amplitude. The success rate was significantly higher with the specific electrodes (81.8% vs 53,3%, p < 0.001). The pacing and sensing thresholds upon implantation were not influenced by the type of lead or by the localization of the cardiac vein that was catheterized (great cardiac vein, lateral vein, postero‐lateral or posterior vein, mid cardiac vein). In contrast, the pacing threshold was significantly lower (0.8 ± 0.2 vs L8 ± 0.8 V; p = 0.002) and the R wave amplitude tended to be greater (13.1 ± 4.5 mV vs 9.3 ± 6.5 mV; p = 0.07) when the tip electrode could be inserted distally into the vein, by comparison with a proximal site near the ostium. At the end of follow‐up (10.2 ± 8.7 months), 34 out of the 35 leads were still fully functional, with a chronic pacing threshold of 1.8 ± 0.7 V and a R wave amplitude of 10.7 ± 6 mV. To conclude, permanent LV pacing via the transvenous route is possible in most patients, with excellent safety and long‐term results.

Driver Domains in Persistent Atrial Fibrillation

Background— Specific noninvasive signal processing was applied to identify drivers in distinct categories of persistent atrial fibrillation (AF). Methods and Results— In 103 consecutive patients with persistent AF, accurate biatrial geometry relative to an array of 252 body surface electrodes was obtained from a noncontrast computed tomography scan. The reconstructed unipolar AF electrograms acquired at bedside from multiple windows (duration, 9±1 s) were signal processed to identify the drivers (focal or reentrant activity) and their cumulative density map. The driver domains were catheter ablated by using AF termination as the procedural end point in comparison with the stepwise-ablation control group. The maps showed incessantly changing beat-to-beat wave fronts and varying spatiotemporal behavior of driver activities. Reentries were not sustained (median, 2.6 rotations lasting 449±89 ms), meandered substantially but recurred repetitively in the same region. In total, 4720 drivers were identified in 103 patients: 3802 (80.5%) reentries and 918 (19.5%) focal breakthroughs; most of them colocalized. Of these, 69% reentries and 71% foci were in the left atrium. Driver ablation alone terminated 75% and 15% of persistent and long-lasting AF, respectively. The number of targeted driver regions increased with the duration of continuous AF: 2 in patients presenting in sinus rhythm, 3 in AF lasting 1 to 3 months, 4 in AF lasting 4 to 6 months, and 6 in AF lasting longer. The termination rate sharply declined after 6 months. The mean radiofrequency delivery to AF termination was 28±17 minutes versus 65±33 minutes in the control group (P<0.0001). At 12 months, 85% patients with AF termination were free from AF, similar to the control population (87%,); P=not significant. Conclusions— Persistent AF in early months is maintained predominantly by drivers clustered in a few regions, most of them being unstable reentries.

Elimination of Local Abnormal Ventricular Activities A New End Point for Substrate Modification in Patients With Scar-Related Ventricular Tachycardia

Background— Catheter ablation of ventricular tachycardia (VT) is effective and particularly useful in patients with frequent defibrillator interventions. Various substrate modification techniques have been described for unmappable or hemodynamically intolerable VT. Noninducibility is the most frequently used end point but is associated with significant limitations, so the optimal end point remains unclear. We hypothesized that elimination of local abnormal ventricular activities (LAVAs) during sinus rhythm or ventricular pacing would be a useful and effective end point for substrate-based VT ablation. As an adjunct to this strategy, we used a new high-density mapping catheter and frequently used epicardial mapping. Methods and Results— Seventy patients (age, 67±11 years; 7 female) with VT and structurally abnormal ventricle(s) were prospectively enrolled. Conventional mapping was performed in sinus rhythm in all, and a high-density Pentaray mapping catheter was used in the endocardium (n=35) and epicardially. LAVAs were recorded in 67 patients (95.7%; 95% confidence interval, 89.2–98.9). Catheter ablation was performed targeting LAVA with an irrigated-tip catheter placed endocardially via a transseptal or retrograde aortic approach or epicardially via the subxiphoid approach. LAVAs were successfully abolished or dissociated in 47 of 67 patients (70.1%; 95% confidence interval, 58.7–80.1). In multivariate analysis, LAVA elimination was independently associated with a reduction in recurrent VT or death (hazard ratio, 0.49; 95% confidence interval, 0.26–0.95; P =0.035) during long-term follow-up (median, 22 months). Conclusions— LAVAs can be identified in most patients with scar-related VT. Elimination of LAVAs is feasible and safe and is associated with superior survival free from recurrent VT. # Clinical Perspective {#article-title-32}Background— Catheter ablation of ventricular tachycardia (VT) is effective and particularly useful in patients with frequent defibrillator interventions. Various substrate modification techniques have been described for unmappable or hemodynamically intolerable VT. Noninducibility is the most frequently used end point but is associated with significant limitations, so the optimal end point remains unclear. We hypothesized that elimination of local abnormal ventricular activities (LAVAs) during sinus rhythm or ventricular pacing would be a useful and effective end point for substrate-based VT ablation. As an adjunct to this strategy, we used a new high-density mapping catheter and frequently used epicardial mapping. Methods and Results— Seventy patients (age, 67±11 years; 7 female) with VT and structurally abnormal ventricle(s) were prospectively enrolled. Conventional mapping was performed in sinus rhythm in all, and a high-density Pentaray mapping catheter was used in the endocardium (n=35) and epicardially. LAVAs were recorded in 67 patients (95.7%; 95% confidence interval, 89.2–98.9). Catheter ablation was performed targeting LAVA with an irrigated-tip catheter placed endocardially via a transseptal or retrograde aortic approach or epicardially via the subxiphoid approach. LAVAs were successfully abolished or dissociated in 47 of 67 patients (70.1%; 95% confidence interval, 58.7–80.1). In multivariate analysis, LAVA elimination was independently associated with a reduction in recurrent VT or death (hazard ratio, 0.49; 95% confidence interval, 0.26–0.95; P=0.035) during long-term follow-up (median, 22 months). Conclusions— LAVAs can be identified in most patients with scar-related VT. Elimination of LAVAs is feasible and safe and is associated with superior survival free from recurrent VT.

Optimizing Hemodynamics in Heart Failure Patients by Systematic Screening of Left Ventricular Pacing Sites : The Lateral Left Ventricular Wall and the Coronary Sinus Are Rarely the Best Sites

OBJECTIVES We sought to evaluate the impact of the left ventricular (LV) pacing site on hemodynamic response to cardiac resynchronization therapy (CRT). BACKGROUND CRT reduces morbidity and mortality in heart failure patients. However, 20% to 40% of eligible patients may not fully benefit from CRT device implantation. We hypothesized that selecting the optimal LV pacing site could be critical in this issue. METHODS Thirty-five patients with nonischemic dilated cardiomyopathy referred for CRT device implantation were studied. Intraventricular dyssynchrony and latest activated LV wall were defined by tissue Doppler imaging analysis before the study. Eleven predetermined LV pacing sites were systematically assessed in random order: basal and mid-cavity (septal, anterior, lateral, inferior), apex, coronary sinus (CS), and the endocardial site facing the CS pacing site. For each patient, +dP/dT(max), -dP/dT(min), pulse pressure, and end-systolic pressure during baseline (AAI) and DDD LV pacing were compared. Two atrioventricular delays were tested. RESULTS Major interindividual and intraindividual variations of hemodynamic response depending on the LV pacing site were observed. Compared with baseline, LV DDD pacing at the best LV position significantly improved +dP/dT(max) (+31 +/- 26%, p < 0.001) and was superior to pacing the CS (+15 +/- 23%, p < 0.001), the lateral LV wall (+18 +/- 22%, p < 0.001), or the latest activated LV wall (+11 +/- 17%, p < 0.001). CONCLUSIONS The pacing site is a primary determinant of the hemodynamic response to LV pacing in patients with nonischemic dilated cardiomyopathy. Pacing at the best LV site is associated acutely with fewer nonresponders and twice the improvement in +dP/dT(max) observed with CS pacing.

Echocardiographic Modeling of Cardiac Dyssynchrony Before and During Multisite Stimulation: A Prospective Study

CAZEAU, S., et al.: Echocardiographic Modeling of Cardiac Dyssynchrony Before and During Multisite Stimulation: A Prospective Study. Multisite biventricular pacing therapy offers significant clinical improvement in some stimulated patients with electrocardiographic criteria of cardiac dyssynchrony. However, observational data increasingly suggest that patients suffering from congestive heart failure in presence of modest QRS widening may also derive benefit from cardiac resynchronization therapy (CRT), and that some patients can be significantly improved clinically after system implantation despite no apparent change in QRS width. This pilot study explored the value of an echocardiographic model to identify cardiac electromechanical dyssynchrony parameters (EDP) in candidates for CRT, and their potential correction after implantation. The study included 66 consecutive CRT recipients of CRT in NYHA functional class III or IV who had one or more atrioventricular, interventricular or intraventricular dyssynchrony criteria. An immediate improvement was observed in 85% of the population with a partial or total correction of their EDP. However, the modifications in EDP differed considerably between recipients of de novo CRT systems and patients with previously implanted standard pacing systems upgraded with the implantation of a left ventricular lead. EDP measurements appear to identify potential candidates for CRT, and to confirm the success of system implantation. (PACE 2003; 26[Pt. II]:137–143)

Outcome After Implantation of a Cardioverter-Defibrillator in Patients With Brugada Syndrome

Background— Brugada syndrome is an arrhythmogenic disease characterized by an increased risk of sudden cardiac death (SCD) by ventricular fibrillation. At present, an implantable cardioverter-defibrillator (ICD) is the recommended therapy in high-risk patients. This multicenter study reports the outcome of a large series of patients implanted with an ICD for Brugada syndrome. Methods and Results— All patients (n=220, 46±12 years, 183 male) with a type 1 Brugada ECG pattern implanted with an ICD in 14 centers between 1993 and 2005 were investigated. ICD indication was based on resuscitated SCD (18 patients, 8%), syncope (88 patients, 40%), or positive electrophysiological study in asymptomatic patients (99 patients, 45%). The remaining 15 patients received an ICD because of a family history of SCD or nonsustained ventricular arrhythmia. During a mean follow-up of 38±27 months, no patient died and 18 patients (8%) had appropriate device therapy (10±15 shocks/patient, 26±33 months after implantation). The complication rate was 28%, including inappropriate shocks, which occurred in 45 patients (20%, 4±3 shocks/patient, 21±20 months after implantation). The reasons for inappropriate therapy were lead failure (19 patients), T-wave oversensing (10 patients), sinus tachycardia (10 patients), and supraventricular tachycardia (9 patients). Among implantation parameters, high defibrillation threshold, high pacing threshold, and low R-wave amplitude occurred, respectively, in 12%, 27%, and 15% of cases. Conclusion— In this large Brugada syndrome population, a low incidence of arrhythmic events was found, with an annual event rate of 2.6% during a follow-up of >3 years, in addition to a significant risk of device-related complications (8.9%/year). Inappropriate shocks were 2.5 times more frequent than appropriate ones.