Morphology of the RV electrogram during LV pacing is related to the hemodynamic effect in cardiac resynchronization therapy

Background: Biventricular (BiV) pacing and left ventricular (LV) pacing both improve LV function in patients with heart failure and LV dyssynchrony. We studied the hemodynamic effect of the atrioventricular (AV) interval and the associated changes in the right ventricular (RV) electrogram (EGM) during LV pacing and compared this with the hemodynamic effect of optimized sequential BiV pacing.
Methods: In 16 patients with New York Heart Association (NYHA) class II to IV, sinus rhythm with normal AV conduction, left bundle branch block (LBBB), QRS > 130 ms, and optimal medical therapy, the changes in RV EGM during LV pacing with varying AV intervals were studied. The hemodynamic effect associated with these changes was evaluated by invasive measurement of LVdP/dt_max and compared with the result of optimized sequential BiV pacing in the same patient.
Results: All patients showed electrocardiographic fusion during LV pacing. The morphology of the RV EGM showed changes in the RV activation that indicated a shift in the extent of fusion from LV pacing. These changes were associated with significant changes in LVdP/dt_max. Baseline LV dP/dt_max was 734 ± 177 mmHg/s, which increased to 927 ± 202 mmHg/s (P<0.0001) with optimized LV pacing and to 920 ± 209 mmHg/s (P<0.0001) with optimized sequential BiV pacing.
Conclusion: The RV EGM is a proper indicator for intrinsic activation over the right bundle during LV pacing and reveals the transition to fusion in the RV EGM that is associated with a decrease in LVdP/dt_max. The hemodynamic effect of optimized LV pacing is equal to optimized sequential BiV pacing.     

Anodal capture in cardiac resynchronization therapy implications for device programming

INTRODUCTION: Right ventricular (RV) anodal capture (AC) has been reported in cardiac resynchronization therapy (CRT), when left ventricular (LV) pacing uses pseudobipolar (LV tip to RV proximal electrode) configuration. The aim of the study was to analyze the prevalence of AC and its implications for device programming. METHODS AND RESULTS: When AC occurred, the resulting QRS morphology was evaluated with the following pacing modes: (1) LV tip pacing plus RV AC, (2) Biventricular (BiV) pacing (i.e., both LV and RV tip pacing), and (3) BiV pacing plus RV AC. Several interventricular pacing (VV) intervals from 50 ms of LV preactivation to 30 ms of RV preactivation were tested in modes 2 and 3. From 38 consecutive patients, AC was achieved in 14 (in 74% of the pacemakers and in none of the defibrillators). LV tip pacing plus RV AC obtained narrower QRS than BiV pacing at all VV intervals in seven of the patients with AC (50%). When BiV pacing is combined with RV AC, it produced a ventricular depolarization through two wave fronts (one from the LV tip and the second from either the ring or the tip of the RV lead depending on the VV interval programmed). CONCLUSIONS: AC obtained the narrowest QRS of all tested pacing modes in a significant proportion of patients undergoing CRT. Though the stimulus was delivered from three sites (BiV pacing plus RV AC mode), only two wave fronts of ventricular activation were seen by ECG.     

Influence of Different Atrioventricular and Interventricular Delays on Cardiac Output During Cardiac Resynchronization Therapy

Restoration of the atrioventricular (AVD) and interventricular (VVD) delays increases the hemodynamic benefit conferred by biventricular (BiV) stimulation. This study compared the effects of different AVD and VVD on cardiac output (CO) during three stimulation modes: BiV-LV = left ventricle (LV) preceding right ventricle (RV) by 4 ms; BiV-RV = RV preceding LV by 4 ms; LVP = single-site LV pacing. We studied 19 patients with chronic heart failure due to ischemic or idiopathic dilated cardiomyopathy, QRS ≥ 150 ms, mean LV end-diastolic diameter = 78 ± 7 mm, and mean LV ejection fraction = 21 ± 3%. CO was estimated by Doppler echocardiographic velocity time integral formula with sample volume placed in the LV outflow tract. Sets of sensed-AVDs (S-AVD) 90–160 ms, paced-AVDs (P-AVD) 120–160 ms, and VVDs 4–20 ms were used. BiV-RV resulted in lower CO than BiV-LV. S-AVD 120 ms and P-AVD 140 ms caused the most significant increase in CO for all three pacing modes. LVP produced a similar increase in CO as BiV stimulation; however, AV sequential pacing was associated with a nonsignificantly higher CO during LVP than with BiV stimulation. CO during BiV stimulation was the highest when LV preceded RV, and VVD ranged between 4 and 12 ms. The most negative effect on CO was observed when RV preceded LV by 4 ms. Hemodynamic improvement during BiV stimulation was dependent both on optimized AVD and VVD. LV preceding RV by 4–12 ms was the most optimal. Advancement of the RV was not beneficial in the majority of patients.     

Segmental Wall Motion Abnormality Analyzed by Equilibrium Radionuclide Angiography and Improvement in Ventricular Function by Cardiac Resynchronization Therapy

Introduction: The purpose of this study was to determine the impact of the left ventricular (LV) segmental wall motion abnormalities detected by equilibrium radionuclide angiography (ERNA) on the improvement in LV and right ventricular (RV) function during biventricular (BIV) stimulation .
Results: We studied 28 patients in NYHA functional classes III or IV and QRS duration >150 ms on resting electrocardiogram. ERNA was performed before and during BIV stimulation at a 6-month follow-up. A significant shortening of QRS duration was observed during BIV stimulation (165 ± 5 ms before vs 133 ± 6 ms during, P < 0.01). Wall motion abnormalities (WMA) were observed in 16 patients (10 with nonischemic cardiomyopathies). In this group, LV and RV ejection fractions (EF) did not increase during BIV stimulation (LVEF = 22 ± 2% vs 20 ± 1.6%, ns; RVEF = 34 ± 3% vs 37 ± 3.8%, ns). Significant increases in RVEF (23 ± 3.2 %→ 38 ± 2.9%, P = 0.001) and LVEF (20 ± 2.5 %→ 30 ± 3%, P = 0.01) were observed in the group of patients without segmental WMA and with global hypokinesia (GH). In this group, a significant decrease in the dispersion in the phase of RV contraction was observed (SD = 39 ± 5 vs 26 ± 2 ms; P < 0.01). WMA predicted an increase in LVEF, in contrast to a baseline 6-minute-walk test, maximal oxygen consumption and LVEF, or amount of QRS shortening.
Conclusions: BIV stimulation increased in LV and RV EF in patients with ventricular dyssynchrony in absence of segmental WMA. ERNA was reliable in the selection of candidates for CRT.     

The effect of anodal stimulation on V-V timing at varying V-V intervals

We studied the effect of anodal capture at the ring electrode of the right ventricular (RV) lead on interventricular (V-V) timing during biventricular (BiV) pacing, in which left ventricular (LV) pacing was preceding RV pacing. The V-V interval was programmed from 80 to 4 ms (LV first) in the LV unipolar (LV tip--generator can) followed by the LV tip-RV ring pacing configuration. In the LV unipolar configuration, V-V programming leads to a continuous change in morphology of the QRS complex according to a change in collision of both activation fronts. When using the LV tip-RV ring configuration with anodal capture at the RV ring electrode no change in QRS morphology was recorded varying the V-V interval from 80 to 60 and 40 ms. However, at V-V intervals between 20 and 4 ms a change in morphology of the QRS complex was recorded, which was due to additional cathodal stimulation of the RV tip electrode during RV stimulation.     

Biventricular upgrading in patients with conventional pacing system and congestive heart failure: results and response predictors

BACKGROUND: There are few studies on cardiac resynchronization therapy (CRT) in heart failure (HF) patients with preexisting right ventricular (RV) pacing. The purpose of this study was to determine the efficacy of CRT upgrading in RV-paced patients and the predictivity of electromechanical dyssynchrony parameters (EDP) evaluated by standard echocardiography (ECHO) and tissue Doppler imaging (TDI). METHODS: Thirty-eight consecutive patients with HF [New York Heart Association (NYHA) class III or IV, LVEF < 35%], prior continuous RV pacing, and absence of atrial fibrillation were enrolled in the presence of a paced QRS > or = 150 ms and evaluated by ECHO and TDI. A responder was defined as a patient with a favorable change in NYHA class and neither HF hospitalization nor death, plus an absolute increase of LVEF > or = 10 units. RESULTS: At six-months follow-up, the whole study population had significant improvement in symptoms, systolic function, and QRS duration (P < 0.001); 32 (84%) patients had a favorable clinical outcome, 25 (66%) were considered responders according to the previous definition. Postimplant QRS was similarly reduced in both responders and nonresponders, whereas EDP had a significant improvement only in responders (P < 0.05). Using EDP, 23 (79%) patients were responders compared with 2 (22%) patients without mechanical dyssynchrony (P = 0.002). CONCLUSIONS: In HF patients with previous RV pacing, CRT is effective to improve clinical, functional outcome, and LV performance and to reduce electromechanical dyssynchrony in a large proportion of patients. Dyssynchrony evaluated by standard and TDI ECHO can be useful for CRT selection of paced patients.     

Bifocal Right Ventricular Cardiac Resynchronization Therapies in Patients with Unsuccessful Percutaneous Lateral Left Ventricular Venous Access

Biventricular cardiac resynchronization therapy (CRT) with a lateral left ventricular (LV) lead cannot always be achieved. We report a single center experience of CRT utilizing a protocol that specifically required the implantation of a bifocal right ventricular (RV) lead system when lateral LV pacing could not be achieved. Consecutive candidates for CRT were included in the study. If strict criteria for lateral LV pacing were not met, they underwent implantation of a bifocal RV lead system with two 7F, active fixation leads, one placed septally at the apex, and the other in the high septal outflow tract. All patients were followed for 12 months and the two groups were compared. A biventricular (BiV) stimulation system was implanted in 44 patients, and a bifocal RV system in six. The demographic characteristics of the two groups were similar. Both groups experienced a similar improvement in functional capacity, increase in 6 minutes walking distance, and decreased need for hospitalizations. The mean increase in LV ejection fraction was 11% in the bifocal RV group versus 10% in the BiV group. Though the tissue Doppler indices of LV synchrony improved earlier in the BiV group, (19% vs 10%) the improvement was similar in both groups at 6 months (23% vs 20%). The clinical improvements conferred by CRT can be matched by a bifocal RV system in selected patients. This alternate approach should be considered when implantation of a LV lateral lead was unsuccessful.     

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)     

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, and 21 ± 27 ms 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.     

Effect of pacing-induced ventricular dyssynchrony on right ventricular function

Background: Asynchronous electrical activation induced by right ventricular (RV) pacing can cause several abnormalities in left ventricular (LV) function. However, the effect of ventricular pacing on RV function has not been well established. We evaluated RV function in patients undergoing long‐term RV pacing. Methods: Eighty‐five patients and 24 healthy controls were included. After pacemaker implantation, conventional echocardiography and strain imaging were used to analyze RV function. Strain imaging measurements included peak systolic strain and strain rate. LV function and ventricular dyssynchrony by tissue Doppler imaging (TDI) were assessed. Intra‐ and interobserver variabilities of TDI parameters were tested on 15 randomly selected cases. Results: All patients were in New York Heart Association functional class I or II and percentage of ventricular pacing was 96 ± 4%. RV apical induced interventricular dyssynchrony in 49 patients (60%). LV dyssynchrony was found in 51 patients (60%), when the parameter examined was the standard deviation of the time to peak myocardial systolic velocity of all 12 segments greater than 34 ms. Likewise, septal‐to‐lateral delay ≥65 ms was found in 31 patients (36%). All echocardiographic indexes of RV function were similar between patients and controls (strain: ?22.8 ± 5.8% vs ?22.1 ± 5.6%, P = 0.630; strain rate: ?1.47 ± 0.91 s^?1 vs ?1.42 ± 0.39 s^?1, P = 0.702). Intra‐ and interobserver variability for RV strain was 3.1% and 5.3%, and strain rate was 1.3% and 2.1%, respectively. Conclusions: In patients with standard pacing indications, RV apical pacing did not seem to affect RV systolic function, despite induction of electromechanical dyssynchrony. (PACE 2011; 34:155–162)     

Acute Hemodynamic Improvement by Pacing in Patients with Severe Congestive Heart Failure

Since the first report on dual chamber pacing for congestive heart failure (CHF) in 1991, a number of investigators have explored the topic with conflicting results. These conflicts may arise from an incomplete understanding of the mechanisms by which pacing improves cardiac function. Potential mechanisms include: (1) increase in filling time: (2) decrease in mitral regurgitation: (3) optimization of left heart mechanical atrioventricular delay (left heart MAVD); and (4) normalization of ventricular activation. One or more of these mechanisms may be operative in an individual patient, implying that patients may require individuol optimization. Acute pacing studies were conducted on nine CHF patients, NYHA Class II-III to Class IV. Measurements of conduction times in sinus rhythm revealed: (1) normal interatrial conduction times (59 ± 5 ms) in all patients, with wide variations in interventricular conduction times (range, ?15–105 ms); and (2) a wide range of left heart MAVD (range, 97–388 ms). While pacing the right, left, or both ventricles, measurement of high fidelity aortic pressure and mitral and aortic velocities revealed the following: (1) 6 of 9 patients increased mean pulse pressure over sinus value during RV orLV pacing at an optimal A V delay: (2) the maximum aortic pulse pressure was achieved when the atrium was not paced: an 8% increase over sinus pulse pressure with paced RV versus a 5% decrease for paced atrium and RV at optimum AV delay (paired Student's t-test, P = 0.01), and a 0% increase over sinus with paced LV versus 7% decrease for paced atrium and LV at optimum AV delay, P < 0.05: (3) significant dependence on pacing site was noted, with 4 patients doing best with RV pacing. 3 patients achieving a maximum with LV pacing, and 2 patients showing no preference; and (4) 2 of 4 patients with restrictive filling patterns were converted to nonrestrictive patterns with optimum pacing. Patient hemodynamics appear to benefit acutely from individually optimized pacing. Increases in filling time, optimization of left heart MAVD, and normalization of intraventricular activation are the most significant mechanisms. Atrial pacing is inferior to atrial sensed modes if the patient has a functional sinus node.     

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%._.     

Does RV Lead Positioning Provide Additional Benefit to Cardiac Resynchronization Therapy in Patients with Advanced Heart Failure?

BACKGROUND AND OBJECTIVES: The left ventricular (LV) stimulation site is currently recommended to position the lead at the lateral wall. However, little is known as to whether right ventricular (RV) lead positioning is also important for cardiac resynchronization therapy. This study compared the acute hemodynamic response to biventricular pacing (BiV) at two different RV stimulation sites: RV high septum (RVHS) and RV apex (RVA). METHODS AND RESULTS: Using micro-manometer-tipped catheter, LV pressure was measured during BiV pacing at RV (RVA or RVHS) and LV free wall in 33 patients. Changes in LV dP/dt(max) and dP/dt(min) from baseline were compared between RVA and RVHS. BiV pacing increased dP/dt(max) by 30.3 +/- 1.2% in RVHS and by 33.3 +/- 1.7% in RVA (P = n.s.), and decreased dP/dt(min) by 11.4 +/- 0.7% in RVHS and by 13.0 +/- 1.0% in RVA (P = n.s.). To explore the optimal combination of RV and LV stimulation sites, we assessed separately the role of RV positioning with LV pacing at anterolateral (AL), lateral (LAT), or posterolateral (PL) segment. When the LV was paced at AL or LAT, the increase in dP/dt(max) with RVHS pacing was smaller than that with RVA pacing (AL: 12.2 +/- 2.2% vs 19.3 +/- 2.1%, P < 0.05; LAT: 22.0 +/- 2.7% vs 28.5 +/- 2.2%, P < 0.05). There was no difference in dP/dt(min) between RVHS- and RVA pacing in individual LV segments. CONCLUSIONS: RVHS stimulation has no overall advantage as an alternative stimulation site for RVA during BiV pacing. RVHS was equivalent with RVA in combination with the PL LV site, while RVA was superior to RVHS in combination with AL or LAT LV site.     

Long-Term Follow-Up of Biventricular Pacing Using a Totally Endocardial Approach in Patients with End-Stage Cardiac Failure

Background: Besides standard left ventricular (LV) stimulation via the coronary sinus, a transseptal approach allows left ventricular endocardial stimulation. We report our long-term observations with biventricular stimulation, using a strictly endocardial system for patients presenting with severe congestive heart failure .
Methods: Six patients with nonischemic cardiomyopathy (mean age = 60 ± 9.6 years, women) in New York Heart Association (NYHA) functional class III (n = 5) or IV, despite optimal drug therapy, and a mean LV ejection fraction of 24 ± 3%, underwent implantation of biventricular stimulation systems between April 1998 and March 1999. All presented with left bundle branch block and an increased LV end-diastolic diameter (mean = 66 ± 5 mm). In all patients, a bipolar pacing lead was implanted in the lateral LV wall using a direct transseptal approach. After implantation, all patients received oral anticoagulation.
Results: QRS duration decreased from 184 ± 22 ms to 108 ± 11 ms. NYHA functional class decreased to II in all patients within 1 month. Over a 85 ± 5 month follow-up, two patients underwent cardiac transplantation, 2 and 4 years after device implantation, respectively; two patients died of end-stage heart failure 4 years after system implantation; and two patients were alive in functional class II. One patient, who experienced syncope due to fast ventricular, underwent implantation of an ICD. One transient ischemic attack occurred in a patient whose anticoagulation was temporarily interrupted .
Conclusions: Long-term endocardial biventricular stimulation via a transseptal approach was safe and effective in this small population. This approach needs to be further compared with conventional epicardial pacing via the coronary sinus     

An Algorithm for Verifying Biventricular Capture Based on Evoked-Response Morphology

Cardiac resynchronization therapy relies on consistent beat-by-beat myocardial capture in both ventricles. A pacemaker ensuring right (RV) and left ventricular (LV) capture through reliable capture verification and automatic output adjustment would contribute to patients' safety and quality of life. We studied the feasibility of an algorithm based on evoked-response (ER) morphology for capture verification in both the ventricles. RV and LV ER signals were recorded in 20 patients (mean age 72.5 years, range 64.3–80.4 years, 4 females and 16 males) during implantation of biventricular (BiV) pacing systems. Leads of several manufacturers were tested. Pacing and intracardiac electrogram (IEGM) recording were performed using an external pulse generator. IEGM and surface-lead electrocardiogram (ECG) signals were recorded under different pacing conditions for 10 seconds each: RV pacing only, LV pacing only, and BiV pacing with several interventricular delays. Based on morphology characteristics, ERs were classified manually for capture and failure to capture, and the validity of the classification was assessed by reference to the ECG. A total of 3,401 LV- and 3,345 RV-paced events were examined. In the RV and LV, the sensitivities of the algorithm were 95.6% and 96.1% in the RV and LV, respectively, and the corresponding specificities were 91.4% and 95.2%, respectively. The lower sensitivity in the RV was attributed to signal blanking in both channels during BiV pacing with a nonzero interventricular delay. The analysis revealed that the algorithm for identifying capture and failure to capture based on the ER-signal morphology was safe and effective in each ventricle with all leads tested in the study.     

Electrocardiographic Diagnosis of Biventricular Pacing in Patients with Nonapical Right Ventricular Leads

Background: Assessment of left ventricular (LV) capture is of paramount importance in patients with biventricular (BiV) pacing. Our goal was to identify electrocardiographic features that differentiate between BiV and right ventricular (RV)‐only pacing in patients with nonapical RV leads. Methods: The study enrolled 300 consecutive patients with BiV devices and nonapical RV leads, and obtained from them 558 electrocardiograms with either BiV pacing (n = 300) or RV‐only pacing (n = 258). RV pacing served as a surrogate for loss of LV capture. Electrocardiograms from the first 150 patients were used to identify BiV‐specific features, and to construct an algorithm to differentiate between BiV and RV‐only pacing. Electrocardiograms from the second 150 patients were used to validate the algorithm. Results: The following electrocardiographic features typical of BiV pacing were identified: QS in lead V6 (specificity = 98.7%, sensitivity = 54.7%), dominant R in lead V1 (specificity = 100%, sensitivity = 23.3%), q in lead V6 (specificity = 96%, sensitivity = 22.7%), and a QRS < 160 ms (specificity = 100%, sensitivity = 66.0%). The algorithm based on those features was found to have an overall diagnostic accuracy of 95.0%, a specificity of 96.0%, and a sensitivity of 93.5%. Conclusions: The study identified QRS features that were very specific for BiV pacing in patients with nonapical RV leads. Sequential arrangement of those features resulted in an algorithm that was very accurate for differentiating between BiV pacing and loss of LV capture. (PACE 2012; 35:1199–1208)     

Invasive optimization of cardiac resynchronization therapy: role of sequential biventricular and left ventricular pacing

BACKGROUND: Aim of this invasive study was to characterize and quantify changes in left ventricular (LV) systolic function due to sequential biventricular pacing (BV) as compared to right atrial triggered simultaneous BV (BV(0)), LV, and right ventricular (RV) pacing in patients with congestive heart failure (CHF). METHODS: In 22 CHF patients, all in sinus rhythm, temporary multisite pacing was performed prior to implantation of a permanent system. LV systolic function was evaluated invasively by the maximum rate of LV pressure increase (dP/dt(max)). Sequential BV pacing was performed with preactivation of either ventricle at 20-80 ms. RESULTS: In comparison to RV pacing, LV and BV(0) pacing increased dP/dt(max) by 33.9 +/- 19.3% and 34.0 +/- 22.6%, respectively (P < 0.001). In 9 patients, optimized sequential BV pacing further improved dP/dt(max) by 8.5 +/- 4.8% compared to BV(0) (range 3.3-17.1, P < 0.05). In 10 patients exhibiting a PR interval < or =200 ms, LV pacing was either superior (n = 6) or equal to BV(0) pacing (n = 4). In these 10 patients, LV pacing yielded a 7.4 +/- 8.0% higher dP/dt(max) than BV(0) pacing (P < 0.05). CONCLUSIONS: Using sequential BV pacing, generally with LV preactivation, moderate improvements in LV systolic function can be achieved in selected patients. Baseline PR interval may aid in the selection of the optimum cardiac resynchronization therapy (CRT) mode, favoring LV pacing in patients with a PR interval < or =200 ms.     

Impact of Temporary Interruption of Right Ventricular Pacing for Heart Block on Left Ventricular Function and Dyssynchrony

Background: The increasing data suggest an association between chronic right ventricular (RV) and left ventricular (LV) dysfunction. We sought to determine the effect of temporary interruption of long-term RV pacing on LV function and mechanical dyssynchrony in children and young adults with complete heart block.
Methods: Twelve patients aged 20.0 ± 7.4 years with congenital heart block (group I) and six patients aged 22.7 ± 11.0 years with surgically acquired heart block (group II) with RV pacing were studied. The pacing rate was reduced to less than patient's intrinsic heart rate and maintained for 5 minutes. The LV ejection fraction (EF), three-dimensional systolic dyssynchrony index (SDI), two-dimensional global longitudinal strain and strain rate, and Doppler-derived isovolumic acceleration before and after interruption of RV pacing were compared.
Results: The LVEF and GLS increased while QRS duration decreased after the pacing interruption in both the groups (all P < 0.05). While SDI decreased in both groups I (6.8 ± 2.3%– 3.8 ± 0.8%, P = 0.001) and II (9.2 ± 4.1 %– 5.0 ± 1.6%, P = 0.032), it remained higher in group II than in group I (P = 0.046) after the pacing interruption. The prevalence of LV dyssynchrony (SDI > 4.7%) decreased in group I (83 %– 25%, P = 0.006) but not in group II (67 %– 50%, P = 0.50). The %increase in LVEF correlated positively with %reduction of LV SDI (r = 0.80, P = 0.001).
Conclusions: Temporary interruption of chronic RV pacing acutely improves LV dyssynchrony and systolic function in children and young adults, the magnitude of which is greater in patients with congenital than those with surgically acquired heart block. (PACE 2010; 41–48)     

Optimal pacing in congenital complete atrioventricular block of immunological origin: interest of multisite stimulation

An infant with a congenital auriculoventricular block (CAVB) of immunological origin was diagnosed prenatally. The mother had Gougerot‐Sjögren disease with positive anti‐Sjogren's Syndrome A (SSA) and Sjogren's Syndrome B (SSB) serologies. Cardiac pacing was necessary and the epicardial route was chosen. Considering the left ventricular (LV) dilatation, biventricular (BiV) stimulation was preferred to the usual DDD mode, presumed to have a deleterious long‐term effect. Echographic parameters were better with BiV stimulation: the asynchronism induced by mono‐RV stimulation was corrected and the QRS complexes were narrower. BiV pacing of a CAVB with LV dilation looks clinically and echographically attractive but needs to be validated in the long term.     

Intracardiac Echocardiography-Guided Cardiac Resynchronization Therapy: Technique and Clinical Application

Background: We undertook a pilot investigation to evaluate the feasibility of a novel technique using intracardiac echocardiography (ICE) for intraoperative assessment of cardiac resynchronization therapy (CRT).
Methods: We evaluated ICE intraoperative imaging of left ventricular (LV) function and aortic valvular flow as well as safety of implementation. ICE was used to guide CRT system lead placement, assess impact of pacing modes, and optimization of device programming.
Results: Twenty-three patients underwent ICE imaging. ICE showed global hypokinesis in six patients, regional wall motion abnormality only in 10 patients, and both in seven patients. Optimized CRT modes included mean atrioventricular (AV) interval of 170 ms and interventricular timing using simultaneous right ventricular (RV)-LV pacing (five patients), LV pacing only (one patient), and sequential LV to RV stimulation (15 patients) or RV to LV stimulation (two patients). ICE-guided CRT acutely improved mean left ventricular ejection fraction (LVEF) from 24 ± 9% to 41 ± 1% (P < 0.00001). During follow-up of 3–24 (mean 11) months, New York Heart Association class improved in all patients from a mean of 3.2 ± 0.4 at implant to 1.6 ± 0.7 (P < 0.0001), with improvement of LVEF from 19 ± 7% to 34 ± 12% (P = 0.0001). Actuarial survival was 83% at 12 months.
Conclusions: (1) ICE imaging is reliable and safe for continuous intraoperative imaging of LV wall motion, and assesses baseline status and impact of CRT interventions. (2) Intraoperative ICE-guided CRT optimization resulted in an increase in LVEF acutely and consistent improvement in heart failure. (3) Sequential biventricular pacing and longer AV interval programming were more often used in ICE-guided CRT.