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.     

Site‐Specific Differences in Latency Intervals during Biventricular Pacing: Impact on Paced QRS Morphology and Echo‐Optimized V‐V Interval

Objective: To investigate differences in latency intervals during right ventricular (RV) pacing and left ventricular (LV) pacing from the (postero‐)lateral cardiac vein in cardiac resynchronization therapy (CRT) patients and their relationship to echo‐optimized interventricular (V‐V) intervals and paced QRS morphology. Methods: We recorded digital 12‐lead electrocardiograms in 40 CRT patients during RV, LV, and biventricular pacing at three output settings. Stimulus‐to‐earliest QRS deflection (latency) intervals were measured in all leads. Echocardiographic atrioventricular (AV) and V‐V optimization was performed using aortic velocity time integrals. Results: Latency intervals were longer during LV (34 ± 17, 29 ± 15, 28 ± 15 ms) versus RV apical pacing (17 ± 8, 15 ± 8, 13 ± 7 ms) for threshold, threshold ×3, and maximal output, respectively (P < 0.001), and shortened with increased stimulus strength (P < 0.05). The echo‐optimized V‐V interval was 58 ± 31 ms in five of 40 (12%) patients with LV latency ≥ 40 ms compared to 29 ± 20 ms in 35 patients with LV latency < 40 ms (P < 0.01). During simultaneous biventricular pacing, four of five (80%) patients with LV latency ≥ 40 ms exhibited a left bundle branch block (LBBB) pattern in lead V₁ compared to three of 35 (9%) patients with LV latency < 40 ms (P < 0.01). After optimization, all five patients with LV latency ≥ 40 ms registered a dominant R wave in lead V₁. Conclusions: LV pacing from the lateral cardiac vein is associated with longer latency intervals than endocardial RV pacing. LV latency causes delayed LV activation and requires V‐V interval adjustment to improve hemodynamic response to CRT. Patients with LV latency ≥ 40 ms most often display an LBBB pattern in lead V₁ during simultaneous biventricular pacing, but a right bundle branch block after V‐V interval optimization. (PACE 2010; 1382–1391)     

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)     

An Implantable Intracardiac Accelerometer for Monitoring Myocardial Contractility

As the myocardium contracts isometrically, it generates vibrations that are transmitted throughout the heart. These vibrations can be measured with an implantable microaccelerometer located inside the tip of an otherwise conventional unipolar pacing lead. These vibrations are, in their audible component, responsible for the first heart sound. The aim of this study was to evaluate, in man, the clinical feasibility and reliability of intracavity sampling of Peak Endocardial Acceleration (PEA) of the first heart sound vibrations using an implantable tip mounted accelerometer. We used a unidirectional accelerometer located inside the stimulating tip of a standard unipolar pacing lead: the sensor has a frequency response of DC to 1 kHz and a sensitivity of 5 mV/G (G - 9.81 m/s^?2). The lead was connected to an external signal amplifier with a frequency range of 0.05–1,000 Hz and to a peak-to-peak detector synchronized with the endocardial R wave scanning the isovolumetric contraction phase. Following standard electro-physiological studies, sensor equipped leads were temporarily inserted in the RV of 15 patients (68 ± 15 years), with normal regional and global ventricular function, to record PEA at rest, during AAI pacing, during VVI pacing, and during dobutamine infusion (up to 20 |mg/kg per min). PEA at baseline was 1.1 G ± 0.5 (heart rate = 75 ± 14 beats/rain) and increased to 1.3 G ± 0.9 (P = NS vs baseline) during AAI pacing (heart rate = 140 beats/min) and to 1.4 G ± 0.5 (P = NS vs baseline) during VVI pacing (heart rate = 140 beats/min). Dobutamine infusion increased PEA to 3.7 G ± 1.1 (P < 0.001 vs baseline), with a heart rate of 121 ± 13 beats/min. In a subset of three patients, simultaneous hemodynamic RV monitoring was performed to obtain RV dP/dt_max, whose changes during dobutamine and pacing were linearly related to changes in PEA (r = 0.9; P < 0.001). In conclusion, the PEA recording can be consistently and safely obtained with an implantable device. Pharmacological inotropic stimulation, but not pacing induced chronotropic stimulation, increases PEA amplitude, in keeping with experimental studies, suggesting that PEA is an index ofmyocardial contractility. Acute variations in PEA are closely paralleled by changes in R V dP/dt_max, but are mainly determined by LV events. The clinical applicability of the method using RV endocardial leads and an implantable device offers potential for diagnostic applications in the long-term monitoring of myocardial function in man.     

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%._.     

Acute recoordination rather than functional hemodynamic improvement determines reverse remodelling by cardiac resynchronisation therapy

Purpose: Cardiac resynchronisation therapy (CRT) improves left ventricular (LV) function acutely, with further improvements and reverse remodelling during chronic CRT. The current study investigated the relation between acute improvement of LV systolic function, acute mechanical recoordination, and long-term reverse remodelling after CRT. Methods: In 35 patients, LV speckle tracking longitudinal strain, LV volumes & ejection fraction (LVEF) were assessed by echocardiography before, acutely within three days, and 6 months after CRT. A subgroup of 25 patients underwent invasive assessment of the maximal rate of LV pressure rise (dP/dt_max,) during CRT-implantation. The acute change in dP/dt_max, LVEF, systolic discoordination (internal stretch fraction [ISF] and LV systolic rebound stretch [SRSlv]) and systolic dyssynchrony (standard deviation of peak strain times [2DS-SD18]) was studied, and their association with long-term reverse remodelling were determined. Results: CRT induced acute and ongoing recoordination (ISF from 45?±?18 to 27?±?11 and 23?±?12%, p?<?0.001; SRS from 2.27?±?1.33 to 0.74?±?0.50 and 0.71?±?0.43%, p?<?0.001) and improved LV function (dP/dt_max 668?±?185 vs. 817?±?198 mmHg/s, p?<?0.001; stroke volume 46?±?15 vs. 54?±?20 and 52?±?16 ml; LVEF 19?±?7 vs. 23?±?8 and 27?±?10%, p?<?0.001). Acute recoordination related to reverse remodelling (r?=?0.601 and r?=?0.765 for ISF & SRSlv, respectively, p?<?0.001). Acute functional improvements of LV systolic function however, neither related to reverse remodelling nor to the extent of acute recoordination. Conclusion: Long-term reverse remodelling after CRT is likely determined by (acute) recoordination rather than by acute hemodynamic improvements. Discoordination may therefore be a more important CRT-substrate that can be assessed and, acutely restored.

     

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.     

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)     

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.     

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.     

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.     

Closed-Loop Stimulation Using Intracardiac Impedance as a Sensor Principle: Correlation of Right Ventricular dP/dtmax and Intracardiac Impedance During Dobutamine Stress Test

OSSWALD, S., et al. : Closed‐Loop Stimulation Using Intracardiac Impedance as a Sensor Principle: Correlation of Right Ventricular dP/dt_max and Intracardiac Impedance During Dobutamine Stress Test. Changes of the unipolar right ventricular impedance during the cardiac cycle are related to the changing content of blood (low impedance) and tissue (high impedance) around the tip of the pacing electrode. During myocardial contraction, the impedance continuously increases reaching its maximum in late systole. This impedance increase is thought to correlate with right ventricular contractility, and thus, with the inotropic state of the heart. In the new Inos² DDDR pacemaker, integrated information from the changing ventricular impedance (VIMP) is used for closed‐loop regulation of the rate response. The aim of this study was to analyze the effect of increasing dobutamine challenge on RV contractility and the measured impedance signals. In 12 patients (10 men, 68 ± 12 years ) undergoing implantation of an Inos² DDDR pacemaker (Biotronik), a right ventricular pigtail catheter was inserted for continuous measurements of RV‐dP/dt_max and simultaneous VIMP signals during intrinsic and ventricular paced rhythm. Then, a stress test with a stepwise increase of intravenous dobutamine (5–20 μg/kg per min ) was performed. To assess the relationship between RV contractility and measured sensor signals, normalized values of dP/dt_max and VIMP were compared by linear regression. There was a strong and highly significant correlation between dP/dt_max and VIMP for ventricular paced (r²= 0.93 ) and intrinsic rhythm (r²= 0.92 ), although the morphologies of the original impedance curves differed quite substantially between paced and intrinsic rhythm in the same patient. Furthermore, VIMP correlated well with sinus rate (r²= 0.82 ), although there were at least four patients with documented chronotropic incompetence. We conclude, that for intrinsic and ventricular paced rhythms sensor signals derived from right ventricular unipolar impedance curves closely correlate with dP/dt_max, and thus, with a surrogate of right ventricular contractility during dobutamine stress testing. Our results suggest that “inotropy‐sensing” via measurement of intracardiac impedance is highly accurate and seems to be a promising sensor principle for physiological rate adaptation in a closed‐loop pacing system.     

Effects of Acute Increases in Left Ventricular Preload on Indices of Myocardial Function in Conscious, Unrestrained and Intact, Tranquilized Baboons

The effects of acute volume loading were examined on indices of left ventricular (LV) function in conscious, unrestrained and intact, tranquilized baboons. Experiments were conducted 1-3 mo after implantation of ultrasonic transducers to measure LV internal diameter and wall thickness, and miniature LV pressure gauges and aortic and left atrial catheters. In 10 intact, tranquilized baboons, rapid volume loading with saline increased LV end-diastolic pressure by 23.7±2.6 mm Hg, LV end-diastolic diameter by 7.8±1.5%, LV stroke work by 37.5±7.8%, while mean arterial pressure and peak LV wall stress did not change significantly. Despite the increase in preload and activation of the Frank-Starling mechanism, LV dP/dt_max and the maximum velocity of myocardial fiber shortening (LV dD/dt_max) did not change. Volume loading after β-adrenergic or combined β-adrenergic and cholinergic blockades or volume loading with blood instead of saline also failed to augment LV dP/dt_max and LV dD/dt_max despite the increase in preload. In order to volume load the baboons in the conscious state, a radiofrequency (RF) interrogator system was devised, which upon receipt of a radio command, activated a battery operated pump to infuse 1,000 ml of saline i.v. to the baboons. In these experiments, preload rose, i.e., LV end-diastolic diameter increased by 13.9±2.1% and the Frank-Starling mechanism could be demonstrated, i.e., stroke work rose by 42.8±7.4%, but LV dP/dt_max and LV dD/dt_max did not change. After preload was depressed by hemorrhage, the rapid infusion of either blood or saline increased LV dP/dt_max by 92.7±18.5% and LV dD/dt_max by 64.3±10.1%. Thus, acute volume loading in the conscious baboons increased LV end-diastolic size and even stroke work substantially. However, preload dependency of LV dP/dt_max and the maximum velocity of myocardial fiber shortening was only encountered at low levels of LV preload.     

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.     

Evaluation of ventricular synchrony using novel Doppler echocardiographic indices in patients with heart failure receiving cardiac resynchronization therapy.

Cardiac resynchronization therapy improves hemodynamics in selected patients with heart failure. Mechanic asynchrony parameters that may guide patient selection or therapy optimization are still being investigated. A biventricular (BiV) pacemaker was implanted in 34 patients with dilated ischemic, idiopathic, or valvular cardiomyopathy, and a QRS duration of > or =130 milliseconds. Two-dimensional standard and Doppler tissue echocardiography was performed during right ventricular (RV), left ventricular (LV), BiV, and no pacing in a random and blinded manner. LV and BiV pacing increased stroke volume (P <.02 for both) and ejection fraction (P <.001 for both). Regional contractility assessed by displacement, strain rate, and peak systolic strain was improved in some segments (P <.05) during LV and BiV pacing. A homogenization of segmental contractions was observed during LV and BiV pacing as evaluated by net systolic displacement and segmental myocardial performance index. LV and BiV pacing provides benefits that can be quantified by echocardiography.     

Pacemaker optimization in nonresponders to cardiac resynchronization therapy: left ventricular pacing as an available option

Background: Echocardiographic (ECHO)‐guided pacemaker optimization (PMO) in cardiac resynchronization therapy (CRT) nonresponders acutely improves left ventricular (LV) function. However, the chronic results of LV pacing in this group are less understood. Methods: We retrospectively studied 28 CRT nonresponders optimized based on ECHO to LV pacing and compared them to 28 age‐ and gender‐matched patients optimized to biventricular (BiV) pacing. ECHOs with tissue Doppler imaging assessed LV hemodynamics before, immediately after, and 29 ± 16 months after PMO. Also, 56 age‐ and gender‐matched CRT responders were included for comparison of clinical outcomes. Results: PMO resulted in acute improvements in longitudinal LV systolic function and several measures of dyssynchrony, with greater improvements in the LV paced group. Chronic improvements in ejection fraction (EF) (3.2 ± 7.7%), and left ventricle end‐systolic volume (LVESV) (?11 ± 36 mL) and one dyssynchrony measure were seen in the combined group. Chronically, both LV and BiV paced patients improved some measures of systolic function and dyssynchrony although response varied between the groups. Survival at 3.5 years was similar (P = 0.973) between the PMO (58%) and nonoptimized groups (58%) but survival free of cardiovascular hospitalization was significantly (P = 0.037) better in the nonoptimized group. Conclusions : CRT nonresponders undergoing PMO to either LV or BiV pacing have acute improvements in longitudinal systolic function and some measures of dyssynchrony. Some benefits are sustained chronically, with improvements in EF, LVESV, and dyssynchrony. A strategy of ECHO‐guided PMO results in survival for CRT nonresponders similar to that of CRT patients not referred for PMO. (PACE 2012; 35:685–694))     

Acute hemodynamic effects of right and left ventricular lead positions during the implantation of cardiac resynchronization therapy defibrillators

Background: To evaluate the acute hemodynamic effects of different right (RV) and left ventricular (LV) pacing sites in patients undergoing the implantation of a cardiac resynchronization therapy defibrillator (CRT‐D). Methods: Stroke volume index (SVI), assessed via pulse contour analysis, and dp/dt max, obtained in the abdominal aorta, were analyzed in 21 patients with New York Heart Association class III heart failure and left bundle branch block (mean ejection fraction of 24 ± 6%), scheduled for CRT‐D implantation under general anesthesia. We compared the hemodynamic effects of RV apical (A), RV septal (B), and biventricular pacing using the worst (lowest SVI; C) and best (highest SVI; D) coronary sinus lead positions. Results: Mean arterial pressure, SVI, and dp/dt max did not differ significantly between RV apical and septal pacing. Dp/dt max and SVI increased significantly during biventricular pacing (dp/dt max: B, 588 ± 160 mmHg/s; C, 651 ± 218 mmHg/s, P = 0.03 vs B; D, 690 ± 220 mmHg/s, P = 0.02 vs C; SVI: B, 33.6 ± 5.5 mL/m², C, 34.8 ± 6.1 mL/m², P = 0.08 vs B, D 36.0 ± 6.0 mL/m², P < 0.001 vs C). The best hemodynamic response was associated with lateral or inferior lead positions in 15 patients. Other LV lead positions were most effective in six patients. Conclusions: The optimal LV lead position varies significantly among patients and should be individually determined during CRT‐D implantation. The impact of the RV stimulation site in patients with intraventricular conduction delay, undergoing CRT‐D implantation, has to be investigated in further studies. (PACE 2011; 34:1537–1543)     

The acute hemodynamic response to LV pacing within individual branches of the coronary sinus using a quadripolar lead

Background: It is not clear whether there is a large difference in acute hemodynamic response (AHR) to left ventricle (LV) pacing in different regions of the same coronary sinus (CS) vein. Using the four electrodes available on a Quartet LV lead, we evaluated the AHR to pacing within individual branches of the CS. Methods: An acute hemodynamic study was attempted in 20 patients. In each patient, we assessed AHR in a number of CS veins and along a significant proportion of each CS branch using three different bipolar configurations. We compared the AHR achieved when pacing using each different vector and also the highest AHR achieved in any position within the same patient with the lowest achieved in that patient. Results : Sixty‐four different CS positions in 19 patients were successfully assessed. No significant difference in AHR was found overall between the three vectors tested. The mean percentage difference in AHR between the CS branch vectors with the lowest and highest dP/dt_max was +6.5 ± 5.4% (P < 0.001). A much larger difference of +16.9 ± 6.1% (P < 0.001) was seen when comparing the highest and lowest AHR achieved using any vector in any position within the same patient. Conclusion: A small difference in AHR is seen when pacing within the same branch of the CS compared to pacing in different branches in the same patient. This suggests that although the site of LV lead placement is important, the position within a CS branch is less important than choosing the right vein. (PACE 2012; 35:196–203)     

The hemodynamic effect of right ventricle (RV), RT3DE targeted left ventricle (LV) and biventricular (BIV) pacing in the early postoperative period after cardiac surgery

Background: Congestive heart failure negatively impacts the prognosis in patients after cardiac surgery. The aim of our study was to assess the value of targeted cardiac resynchronization therapy (CRT) within 72 hours after cardiac surgery in patients with mechanical dyssynchrony, who had an ejection fraction ≤ 35%, QRS ≥150 ms or between 120 and 150 ms. Methods: A prospective randomized trial based on three‐dimensional echocardiography (RT3DE) and optimized sequential dual‐chamber (DDD ) pacing in patients after cardiac surgery. DDD epicardial pacing (Medtronic coaxial epicardial leads 6495) was provided by a modified Medtronic INSYNC III Pacemaker (Medtronic Inc., Minneapolis, MN, USA). Summary of results: The study included 21 patients with ischemic heart disease (HD) or valvular HD (16 men, 5 women, average age 69 years) with left ventricle (LV) dysfunction after cardiac surgery . Patients with biventricular (BIV) (CO 6.7 ± 1.7 L/min, CI 3.5 ± 0.8 L/min/m²) and LV (CO 6.2 ± 1.5 L/min, CI 3.2 ± 0.7 L/min/m²) pacing had statistically significantly higher CO and CI than patients with right ventricular (RV) (CO 5.4 ± 1.4 L/min, CI 2.8 ± 0.6 L/min/m²) pacing (BIV vs RV P ≤ 0.001; LV vs RV P ≤ 0.05; BIV vs LV P ≤ 0.05). Conclusions: RT3DE targeted and optimized CRT in the early postperative period after cardiac surgery provided better hemodynamic results than RV pacing. (PACE 2011; 34:1231–1240)