Radiographic left ventricular-right ventricular interlead distance predicts the acute hemodynamic response to cardiac resynchronization therapy

Radial strain imaging-guided lead placement for improving response to cardiac resynchronization therapy in patients with ischaemic cardiomyopathy: the raise cardiac resynchronization therapy trial

AIMS

To evaluate the benefit of speckle tracking radial strain imaging (STRSI)-guided left ventricular (LV) lead (LVL) positioning in cardiac resynchronization therapy (CRT) in patients (pts) with ischaemic cardiomyopathy with CRT indication.

METHODS AND RESULTS

We conducted a prospective randomized controlled trial. Patients were enrolled in nine centres with 2:1 randomization into two groups (guided vs. control). Patients underwent STRSI to identify the optimal LV position from six LV segments at midventricular level. Implantation via STRSI was attempted for recommended segment in the guided group only. Follow-up included echocardiography (6 months) and clinical evaluation (6 and 12 months). The primary endpoint was comparison % reduction in LV end-systolic volume at 6 months with baseline. Secondary endpoints included hospitalizations for heart failure and death, and improvement in additional echocardiographic measurements and quality of life score. A total of 172 patients (115 guided vs. 57 control) were enrolled. In the guided group, 60% of the implanted LV leads were adjudicated to be successfully located at the recommended segment, whereas in the control group 44% reached the best STRSI determined segment. There was no difference between the groups in any of the primary or secondary endpoints at 6 and 12 months.

CONCLUSION

Our findings suggest that echo-guided implantation of an LV lead using STRSI does not improve the clinical or echocardiographic response compared with conventional implantation.

Right ventricular lead location and outcomes among patients with cardiac resynchronization therapy: A meta-analysis

BACKGROUND

Cardiac resynchronization therapy (CRT) has been demonstrated to improve heart failure (HF) symptoms, reverse LV remodeling, and reduce mortality and HF hospitalization (HFH) in patients with a reduced left ventricular (LV) ejection fraction (LVEF). Prior studies examining outcomes based on right ventricular (RV) lead position among CRT patients have provided mixed results. We performed a systematic review and meta-analysis of randomized controlled trials and prospective observational studies comparing RV apical (RVA) and non-apical (RVNA) lead position in CRT.

METHODS

Our meta-analysis was constructed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for systematic reviews and meta-analyses. We searched EMBASE and MEDLINE. Eligible studies reported on at least one of the following outcomes of interest: all-cause mortality, the composite endpoint of death and first HFH hospitalization, change in LVEF, New York Heart Association (NYHA) class improvement, and change in LV end systolic volume (LVESV). We performed meta-analysis summaries using a DerSimonian-Laird random-effects model and conservatively used the Knapp-Hartung approach to adjust the standard errors of the estimated model coefficients.

RESULTS

We included nine studies representing a total of 1832 patients. Of those, 1318 (72%) patients had RVA lead placement and 514 (28%) had RVNA lead placement. The mean age of patients was 65.5 ± 4.4 years, and they were predominantly men (69%-97%). There was no statistically significant difference in all-cause mortality by RVA vs. RVNA (OR = 0.77, 95% CI 0.32-1.89; I2 = 16.7%, p = 0.31), or in the combined endpoint of all-cause mortality and first HFH (OR 0.88, 95% CI 0.62-1.25; I2 = 0%, p = 0.84). Also, there was no difference between RVA and RVNA for NYHA class improvement (OR = 1.03, 95% CI 0.9-1.17; I2 = 0%, p = 0.99), change in LVEF (mean difference (MD) = 1.33, 95% CI -1.45 to 4.10; I2 = 47%; p = 0.093), and change in LVESV (MD = -1.11, 95% CI -3.34 to 1.12; I2 = 0%; p = 0.92).

CONCLUSION

This meta-analysis shows that in CRT pacing, RV lead position does not appear to be associated with clinical outcomes or LV reverse remodeling. Further studies should focus on the relationship of RV lead vis-à-vis LV lead location, and its clinical importance.

Paced or sensed conduction time to determine programming with cardiac resynchronization therapy: The PASED-CRT Trial

BACKGROUND

Cardiac resynchronization therapy (CRT) is a well-established treatment for patients with drug refractory heart failure.

OBJECTIVES

This study sought to compare the longest RV_sense to LV_sense activation time (sLAT) versus the longest RV_pace to LV_sense activation time (pLAT) as the programmed site for left ventricular (LV) pacing in CRT patients with quadripolar LV leads at 3 months.

METHODS

This single site, double-blinded, prospective trial, randomized patients 1:1 into the sLAT or pLAT group to determine response. LV pacing was programmed at implant and maintained through 3 months of follow-up. The 6-minute hall walk (6MHW) test, NYHA, Minnesota living with heart failure, and clinical composite score (CCS) at the 3 months was compared.

RESULTS

N = 92 patients (73M:19F age 66 ± 11.3 years) were randomized implanted and programmed per protocol. Baseline characteristics were comparable. N = 39 sLAT and N = 34 pLAT completed the 3-month visit for final analysis. Significant improvement from baseline to 3 months was seen in the sLAT group from 253.9 (+/-11.5) to 323.1 (+/-11.9) P = .001. Similarly, the pLAT group improved from 274.9 (+/-16.15) to 343.9 (+/-15.9) P = .003. The difference between these groups, however, did not reach significance (P = .86). The pLAT group demonstrated a higher responder rate of (71%) versus the sLAT group (64%) based on the CCS although not reaching significance (P = .56).

CONCLUSIONS

Use of both the pLAT and sLAT method of programming demonstrated significant improvement in 6MHW distance at 3 months with pLAT demonstrating a slightly higher responder rate based on CCS (P = .56). pLAT should be considered at minimum as equivalent in patients with no intrinsic conduction.

CRT Optimization: What Is New? What Is Necessary?

Cardiac resynchronization therapy (CRT) has proven to improve quality of life, reduce heart failure hospitalization, and prolong life in selected heart failure patients with reduced ejection fraction, on optimal medical therapy and with electrical dyssynchrony. To ensure maximal benefit for CRT patients, optimization of care should be implemented. This begins with appropriate referring as well as selecting patients, knowing that the presence of left bundle branch block and QRS ≥ 150 ms is associated with the greatest reverse remodeling. The LV lead, preferably quadripolar, is best targeted in a postero-lateral position. After implantation, optimal device programming should aim for maximal biventricular pacing and in selected cases further electrical delay optimization might be of use. Even as important, is the implementation of thorough multidisciplinary heart failure care with medication uptitration, remote monitoring, rehabilitation, and patient education. The role of newer pacing strategies as endocardial or His-bundle pacing remains the subject of ongoing investigation.

How to Implant Cardiac Resynchronization Therapy in a Busy Clinical Practice

Implantation of cardiac resynchronization therapy devices represents one of the more challenging and time-consuming procedures for the clinical electrophysiologist. This article reviews several strategies used to improve efficiency, safety, and effectiveness of cardiac resynchronization therapy implantation. The cornerstone of our strategy to improve efficiency, safety, and quality of cardiac resynchronization therapy implantation is the use of a telescoping guide system with high-quality venography. Competency in subclavian venoplasty and snaring techniques are essential to maintain efficiency and effectiveness during difficult cases.

Contractility surrogates derived from three-dimensional lead motion analysis and prediction of acute haemodynamic response to CRT

Background

Patient-specific left ventricular (LV) lead optimisation strategies with immediate feedback on cardiac resynchronisation therapy (CRT) effectiveness are needed. The purpose of this study was to compare contractility surrogates derived from biventricular lead motion analysis to the peak positive time derivative of LV pressure (dP/dt_max) in patients undergoing CRT implantation.

Methods

Twenty-seven patients underwent CRT implantation with continuous haemodynamic monitoring. The right ventricular (RV) lead was placed in apex and a quadripolar LV lead was placed laterally. Biplane fluoroscopy cine films facilitated construction of three-dimensional RV–LV interlead distance waveforms at baseline and under biventricular pacing (BIVP) from which the following contractility surrogates were derived; fractional shortening (FS), time to peak systolic contraction and peak shortening of the interlead distance (negative slope). Acute haemodynamic CRT response was defined as LV ∆dP/dt_max ≥ 10 %.

Results

We observed a mean increase in dP/dt_max under BIVP (899±205 mm Hg/s vs 777±180 mm Hg/s, p<0.001). Based on ΔdP/dt_max, 18 patients were classified as acute CRT responders and nine as non-responders (23.3%±10.6% vs 1.9±5.3%, p<0.001). The baseline RV–LV interlead distance was associated with echocardiographic LV dimensions (end diastole: R=0.61, p=0.001 and end systole: R=0.54, p=0.004). However, none of the contractility surrogates could discriminate between the acute CRT responders and non-responders (ΔFS: −2.5±2.6% vs − 2.0±3.1%, p=0.50; Δtime to peak systolic contraction: −9.7±18.1% vs −10.8±15.1%, p=0.43 and Δpeak negative slope: −8.7±45.9% vs 12.5±54.8 %, p=0.09).

Conclusion

The baseline RV–LV interlead distance was associated with echocardiographic LV dimensions. In CRT recipients, contractility surrogates derived from the RV–LV interlead distance waveform could not discriminate between acute haemodynamic responders and non-responders.

A Planning and Guidance Platform for Cardiac Resynchronization Therapy

Patients with drug-refractory heart failure can greatly benefit from cardiac resynchronization therapy (CRT). A CRT device can resynchronize the contractions of the left ventricle (LV) leading to reduced mortality. Unfortunately, 30%-50% of patients do not respond to treatment when assessed by objective criteria such as cardiac remodeling. A significant contributing factor is the suboptimal placement of the LV lead. It has been shown that placing this lead away from scar and at the point of latest mechanical activation can improve response rates. This paper presents a comprehensive and highly automated system that uses scar and mechanical activation to plan and guide CRT procedures. Standard clinical preoperative magnetic resonance imaging is used to extract scar and mechanical activation information. The data are registered to a single 3-D coordinate system and visualized in novel 2-D and 3-D American Heart Association plots enabling the clinician to select target segments. During the procedure, the planning information is overlaid onto live fluoroscopic images to guide lead deployment. The proposed platform has been used during 14 CRT procedures and validated on synthetic, phantom, volunteer, and patient data.

Maximization of interventricular conduction time by means of quadripolar leads for cardiac resynchronization therapy

PURPOSE

Identifying the left ventricular (LV) site associated with the maximum spontaneous interventricular conduction time (right ventricle (RV)-to-LV interval) has proved to be an effective strategy for optimal LV pacing site selection in cardiac resynchronization therapy (CRT). The aim of our study was to determine whether quadripolar LV lead technology allows RV-to-LV interval maximization.

METHODS

We enrolled 108 patients undergoing implantation of a CRT system using an LV quadripolar lead and 114 patients who received a bipolar lead. On implantation, the RV-to-LV interval was measured for the dipole of the bipolar leads and for each electrode of the LV lead (tip, ring 2, ring 3, ring 4).

RESULTS

In the quadripolar group, the mean RV-to-LV interval ranged from 90 ± 33 ms (tip) to 94 ± 32 ms (R4) (p > 0.05 for all comparisons). In 55 (51%) patients, the RV-to-LV interval was > 80 ms at all electrodes, while in 27 (25%) patients, no electrodes were associated with an RV-to-LV interval > 80 ms. At least one LV pacing electrode was associated with an RV-to-LV interval > 80 ms in 62 (70%) patients with a short (36 mm) inter-electrode distance, and in 19 (95%, p = 0.022) of those with a long distance (50.5 mm). In the bipolar group, the mean RV-to-LV interval was 72 ± 37 ms (p < 0.001 versus quadripolar). The RV-to-LV interval was > 80 ms in 44 (39%) patients (p < 0.001 versus quadripolar leads with both short and long inter-electrode distance).

CONCLUSIONS

Quadripolar leads allow RV-to-LV interval maximization. An optimal RV-to-LV interval seems achievable in the majority of patients, especially if the leads present a long inter-electrode distance.

Three-dimensional interlead distance predicts response and outcomes after cardiac resynchronization therapy

BACKGROUND

Approximately one-third of patients do not respond favourably to cardiac resynchronization therapy (CRT). A longer distance between ventricular leads may improve response.

AIM

To study the impact of the true three-dimensional interlead distance (ILD) on outcomes.

METHODS

Consecutive patients undergoing CRT device implantation were included prospectively. Interlead separation was measured from postprocedural anterior-posterior and lateral chest X-rays. The three-dimensional ILD was calculated using the Pythagorean theorem. Response to CRT was defined using a composite clinical score at 6 months.

RESULTS

Forty-two patients were included (mean age 70±9 years; QRS duration 154±31ms; left ventricular ejection fraction 26±7%; 50% ischaemic). At 6 months, 71% of patients were considered to be responders. Responders had a significantly longer ILD (108±17 vs. 87±21mm; P=0.002). When the ILD was corrected for cardiac size, the optimal cut-off value was ≥ 0.53 for predicting response (sensitivity 83%, specificity 75%, area under the curve 0.84; P=0.0002). Similar results were obtained in a historical retrospective cohort. The use of proximal electrodes on the left ventricular lead was associated with a longer ILD in 95% of patients, compared with more distal pacing configurations. In the total cohort of 74 patients (median follow-up, 420 days), those with an indexed ILD ≥ 0.53 had a 70% reduction in risk of hospitalization for heart failure (P=0.004).

CONCLUSION

Longer three-dimensional ILD corrected for cardiac size measured on chest radiographs can accurately predict response to CRT and outcomes. This simple variable may be used to identify optimal lead placement and pacing configuration during CRT implantation.

Advances and Future Directions in Cardiac Pacemakers: Part 2 of a 2-Part Series

In the second part of this 2-part series on pacemakers, we present recent advances in pacemakers and preview future developments. Cardiac resynchronization therapy (CRT) is a potent treatment for heart failure in the setting of ventricular dyssynchrony. Successful CRT using coronary venous pacing depends on appropriate patient selection, lead implantation, and device programming. Despite optimization of these factors, nonresponse to CRT may occur in one-third of patients, which has led to a search for alternative techniques such as multisite pacing, His bundle pacing, and endocardial left ventricular pacing. A paradigm shift in pacemaker technology has been the development of leadless pacemaker devices, and on the horizon is the development of batteryless devices. Remote monitoring has ushered in an era of greater safety and the ability to respond to device malfunction in a timely fashion, improving outcomes.

Coronary Sinus Lead Positioning

Although cardiac resynchronization therapy improves morbidity and mortality in patients with cardiomyopathy, heart failure, and electrical dyssynchrony, the rate of nonresponders using standard indications and implant techniques is still high. Optimal coronary sinus lead positioning is important to increase the chance of successful resynchronization. Patient factors such as cause of heart failure, type of dyssynchrony, scar burden, coronary sinus anatomy, and phrenic nerve capture may affect the efficacy of the therapy. Several modalities are under investigation. Alternative left ventricular lead implantation strategies are occasionally required when the transvenous route is not feasible or would result in a suboptimal lead position.

Coronary Sinus Lead Positioning

Although cardiac resynchronization therapy improves morbidity and mortality in patients with cardiomyopathy, heart failure, and electrical dyssynchrony, the rate of nonresponders using standard indications and implant techniques is still high. Optimal coronary sinus lead positioning is important to increase the chance of successful resynchronization. Patient factors such as cause of heart failure, type of dyssynchrony, scar burden, coronary sinus anatomy, and phrenic nerve capture may affect the efficacy of the therapy. Several modalities are under investigation. Alternative left ventricular lead implantation strategies are occasionally required when the transvenous route is not feasible or would result in a suboptimal lead position.

Biventricular paced QRS predictors of left ventricular lead locations in relation to mortality in cardiac resynchronization therapy

BACKGROUND

Left ventricular (LV) lead location during cardiac resynchronization therapy (CRT) has influenced mortality and heart failure events; however the biventricular paced QRS morphology has not been established as a predictor of LV lead location or mortality.

METHODS

We evaluated the biventricular paced QRS morphology in 306 patients undergoing CRT in relation to specific anatomic locations. A logistic regression model and Kaplan-Meier survival estimates were used to determine predictors of LV lead location and survival.

RESULTS

The mean age was 68±13years. Predictors of LV lead location from anterior, lateral, and posterior segments were: absence of R in V1, QS in aVL; and R in aVL, respectively. Absence of an R in II, III, or aVF predicted an inferior site. A QS in V4-V6 differentiated apical from basal sites (p=0.01). LV pacing from sites along the middle cardiac vein revealed a higher mortality (34%), than lateral sites (20%, p=0.02).

CONCLUSIONS

Biventricular paced QRS criteria were predictive of LV lead locations. The proposed algorithm enhanced the predictive accuracy of these criteria. LV pacing sites along the middle cardiac vein were associated with increased mortality.

Interventricular lead separation is critical for NT-proBNP reduction after cardiac resynchronization therapy

AIMS

Effective cardiac resynchronization therapy may depend upon the distance between left ventricular (LV) and right ventricular (RV) pacing leads. We assessed the influence of lead separation upon circulating NT-proBNP.

MATERIALS & METHODS

In total, 132 patients underwent assessment, including NT-proBNP assay, before and after cardiac resynchronization therapy. 3D lead separation was calculated from postero-anterior and lateral chest radiography.

RESULTS

Lead separation correlated with NT-proBNP reduction (r = 0.25; p = 0.004). Circulating NT-proBNP only fell in those with lead separation in the upper two quartiles. Deteriorating NT-proBNP occurred in 44 patients. Lead separation was less in these patients compared with those with an improvement (corrected 3D lead separation: 148.0 ± 5.38 and 170.5 ± 4.21 mm, respectively; p = 0.0018).

CONCLUSION

Left ventricular-right ventricular lead separation correlates with postcardiac resynchronization therapy improvements in circulating NT-proBNP, a powerful marker of heart failure status and prognosis. Attention should be paid to achieving maximal lead separation at implantation.

Complex cardiac pacing in the setting of a district general hospital: procedural success and complications

BACKGROUND AND PURPOSE

Complex cardiac pacing with either an implantable cardiovertor defibrillator (ICD) or a biventricular pacemaker with pacing only (CRT-P) or biventricular pacemaker with implantable cardiovertor defibrillator (CRT-D) plays an important role in the management of patients with heart failure. However, device implantation is associated with rare but significant complications which may limit the number of centres offering this treatment. The aim of this study is to define procedural success and complication rates associated with implantation of complex implantable cardiac devices in a district general hospital.

METHODS AND SUBJECTS

The pacing records of all the patients who underwent complex cardiac pacing (ICD, CRT-P and CRT-D) between January 2010 and December 2011 were reviewed. Information on clinical characteristics, pacing indications, venous access, implantation data, lead stability at follow-up, and procedure-related complications were obtained.

RESULTS

A total of 151 devices (60 CRT-Ds, 55 CRT-Ps and 36 ICDs), were implanted between January 2010 and December 2011 with a median follow-up of 12 months. Overall transvenous procedural success rate was 99.3%. 14 (9.3%) out of the 151 patients suffered a complication. There were no procedure-related deaths, and lead displacement (5.3%) was the most common complication. Other complications included pocket haematoma and phrenic nerve stimulation (1.3% and 3.4%, respectively). There were no cases of pneumothorax, cardiac tamponade, device-related infection, symptomatic venous thrombosis and stroke. Lead thresholds, in particular that of the left ventricular lead, remained stable during the follow-up period indicating persistent delivery of cardiac resynchronisation therapy in the group receiving CRT systems.

CONCLUSIONS

In the presence of necessary clinical expertise, complex cardiac devices can be implanted successfully and with a high degree of safety in the setting of a district general hospital.

Contemporary and future trends in cardiac resynchronization therapy to enhance response

The rationale for cardiac resynchronization therapy (CRT), expectations in terms of patient benefit, patient selection for CRT, selection of a CRT pacemaker (CRT-P) vs CRT plus implantable cardioverter-defibrillator (CRT-D) platform, and studies evaluating device programming to enhance benefit from CRT are reviewed. The notion of an "optimal" left ventricular (LV) pacing site, the rationale for identifying and avoiding LV pacing in regions of scar, the use of anatomic, hemodynamic, and electrical parameters to identify an optimal LV pacing site, and the potential utility of multisite LV pacing to enhance benefit from CRT are discussed. Finally, the advantages and disadvantages of the various methods for LV lead delivery are reviewed.

Clinical, laboratory, and pacing predictors of CRT response

A decade of research has established the role of cardiac resynchronization therapy (CRT) in medically refractory, moderate to severe systolic heart failure (HF) with intraventricular conduction delay. CRT is an electrical therapy instituted to reestablish ventricular synchronization in order to improve cardiac function and favorably modulate the neurohormonal system. CRT confers a mortality benefit, improved HF hospitalizations, and functional outcome in this population, but not all patients consistently demonstrate a positive CRT response. The nonresponder rate varies from 20% to 40%, depending on the defined response criteria. Efforts to improve response to CRT have focused on a number of fronts. Methods to optimize the correction of electrical and mechanical dyssynchrony, which is the primary target of CRT, has been the focus of research, in addition to improving patient selection and optimizing post-implant care. However, a major issue in dealing with improving nonresponse rates has been finding an accurate and generally accepted definition of "response" itself. The availability of a standard consensus definition of CRT response would enable the estimation of nonresponder burden accurately and permit the development of strategies to improve CRT response. In this review, we define various aspects of "response" to CRT and outline variability in the definition criteria and the problems with its inconsistencies. We describe clinical, laboratory, and pacing predictors that influence CRT response and outcome and how to optimize response.

Lead positioning strategies to enhance response to cardiac resynchronization therapy

Left ventricular lead position is one of the main determinants of CRT response. There are several approaches in LV lead positioning that include favoring an optimal anatomical position or targeting either the segment with maximal mechanical dyssynchrony or a region with maximal electrical delay. The conventional LV lead implantation faces several technical difficulties that may prevent the obtaining of a stable position and good performance of the LV lead without phrenic nerve stimulation. In addition, implant of the LV pacing lead in areas with myocardial scar may result in less than optimal cardiac resynchronization. Several strategies have been proposed to overcome all these obstacles including multimodality cardiac imaging to help in preprocedural or intraprocedural identification of the latest activated areas of the LV and the potential anatomical constraints. In selected patients, the surgical implant may be a solution to overcome these constraints. In the future, LV endocardial or epicardial multisite pacing may deliver an enhanced response to CRT.

The effect of left ventricular pacing site on cardiac resynchronization therapy outcome and mortality: the results of a PROSPECT substudy

AIMS

Left ventricular pacing site (LV-PS) was prospectively collected to test the influence of the anatomical LV-PS on the outcome of cardiac resynchronization therapy (CRT) and mortality.

METHODS AND RESULTS

Four hundred and twenty-six patients with standard indications for CRT underwent echocardiographic and clinical evaluation before and after CRT implantation. The LV-PS was determined from fluoroscopy using the clockwise principle (CP). The LV-PS was categorized into three prospectively defined groups: between 3 and 5 o'clock and longitudinal basal/mid-position (Group A, 'optimal'); between 12 and 2 o'clock and longitudinal mid-apical anterior position (Group B, 'non-optimal'); and all other (Group C, 'other'). Of 333 patients, followed for 0.9 years (mean), adequate images were available to define the LV-PS. Left ventricular pacing site was Group A for 118 patients, Group B for 56, and Group C for 159. The three groups were comparable regarding gender, aetiology, and NYHA class; however, patients in Group A were younger. No relation was found between the LV-PS groups and CRT outcome or all-cause mortality. However, further exploratory subanalyses suggest that LV-PS may impact outcomes in non-ischaemic patients, those with left bundle branch block, and when LV-PS is apical in location.

CONCLUSION

Using the CP to define anatomical LV-PS, no relation was found between the LV-PS groups and CRT outcome and mortality. Exploratory analyses warrant further studies.

Backup right ventricular pacing with a 0.035'' guidewire during implantation of left ventricular leads

INTRODUCTION

During implantation of biventricular devices, manipulation of the guiding sheath during localization of the coronary sinus (CS) ostium may result in injury to the right bundle and complete heart block. A preventive measure is to implant the right ventricular (RV) lead first, though this may interfere with manipulation of the guiding sheath and dislodge the permanent lead. We tested the feasibility of backup pacing with a 0.035'' guidewire, advanced through the guiding sheath during CS localization.

METHODS

One hundred six consecutive patients (mean age = 70 +/- 11 years, 81 men) undergoing biventricular device implantation were studied. A 0.035'' guidewire with an uncoated tip was advanced into the right ventricle through the guiding sheath, and unipolar capture threshold, R-wave sensing amplitude, and pacing impedance were measured.

RESULTS

RV pacing was successful in all patients. The mean capture threshold was 3.8 +/- 2.1 V/0.5 ms, R-wave amplitude 5.4 +/- 4.3 mV, and pacing impedance 226 +/- 78 Omega. No arrhythmia was observed during the tests. Two patients developed complete heart block during the implant procedure and were successfully paced temporarily using the 0.035'' guidewire.

CONCLUSION

Temporary RV pacing, using a 0.035'' guidewire within the guiding sheath, is a simple, reliable, and safe method that allows backup pacing in case of traumatic complete heart block, developing during the implantation of biventricular devices.

Contemporary pacemakers: what the primary care physician needs to know

Pacemaker therapy is most commonly initiated because of symptomatic bradycardia, usually resulting from sinus node disease. Randomized multicenter trials assessing the relative benefits of different pacing modes have made possible an evidence-based approach to the treatment of bradyarrhythmias. During the past several decades, major advances in technology and in our understanding of cardiac pathophysiology have led to the development of new pacing techniques for the treatment of heart failure in the absence of bradycardia. Left ventricular or biventricular pacing may improve symptoms of heart failure and objective measurements of left ventricular systolic dysfunction by resynchronizing cardiac contraction. However, emerging clinical data suggest that long-term right ventricular apical pacing may have harmful effects. As the complexity of cardiac pacing devices continues to grow, physicians need to have a basic understanding of device indications, device function, and common problems encountered by patients with devices in the medical and home environment.

Reversing cardiac resynchronization therapy non-responder status in a patient with a surgically placed epicardial left ventricular lead by switching to an active fixation coronary sinus lead

This report describes the reversal of a cardiac resynchronization therapy non-responder status in a patient with a surgically placed left ventricular lead by the use of a newly available active fixation coronary sinus lead.

Usefulness of high-speed rotational coronary venous angiography during cardiac resynchronization therapy

Standard coronary venous angiography (SCVA) provides a static, fixed projection of the coronary venous (CV) tree. High-speed rotational coronary venous angiography (RCVA) is a novel method of mapping CV anatomy using dynamic, multiangle visualization. The purpose of this study was to assess the value of RCVA during cardiac resynchronization therapy. Digitally acquired rotational CV angiograms from 49 patients (mean age 69 +/- 11 years) who underwent left ventricular lead implantation were analyzed. RCVA, which uses rapid isocentric rotation over a 110 degrees arc, acquiring 120 frames/angiogram, was compared with SCVA, defined as 2 static orthogonal views: right anterior oblique 45 degrees and left anterior oblique 45 degrees . RCVA demonstrated that the posterior vein-to-coronary sinus (CS) angle and the left marginal vein-to-CS angle were misclassified in 5 and 11 patients, respectively, using SCVA. RCVA identified a greater number of second-order tributaries with diameters >1.5 mm than SCVA. The CV branch selected for lead placement was initially identified in 100% of patients using RCVA but in only 74% of patients using SCVA. RCVA showed that the best angiographic view for visualizing the CS and its tributaries differed significantly among different areas of the CV tree and among patients. The area of the CV tree that showed less variability was the CS ostium, which had a fairly constant relation with the spine in shallow right anterior oblique and left anterior oblique projections. In conclusion, RCVA provided a more precise map of CV anatomy and the spatial relation of venous branches. It allowed the identification of fluoroscopic views that could facilitate cannulation of the CS. The final x-ray view displaying the appropriate CV branch for left ventricular lead implantation was often different from the conventional left anterior oblique and right anterior oblique views. RCVA identified the target branch for lead implantation more often than SCVA.

Variability of coronary venous anatomy in patients undergoing cardiac resynchronization therapy: a high-speed rotational venography study

BACKGROUND

Imaging the coronary venous (CV) tree to delineate the coronary sinus and its tributaries can facilitate electrophysiological procedures, such as cardiac resynchronization therapy (CRT) and catheter ablation. Venography also allows visualization of the left atrial (LA) veins, which may be a potential conduit for ablative or pacing strategies given their proximity to foci that can trigger atrial fibrillation.

OBJECTIVE

The aim of this study was to provide a detailed description of CV anatomy using rotational venography in patients undergoing CRT.

METHODS

Coronary sinus (CS) size and the presence, size, and angulation of its tributaries were determined from the analysis of rotational CV angiograms from 51 patients (age 68 +/- 11 years; n = 12 women) undergoing CRT.

RESULTS

The CS, posterior veins, and lateral veins were identified in 100%, 76%, and 91% of patients. Lateral veins were less prevalent in patients with a history of lateral myocardial infarction than in patients without such a history (33% vs. 96%; P = .014). The diameters of the CS and its tributaries were fairly variable (7.3-18.9 mm for CS, 1.3-10.5 mm for CS tributaries). The CS was larger in men than in women and in cases of ischemic than in cases of nonischemic cardiomyopathy (all P <.05). The vein of Marshall, the most constant LA vein, was identified in 37 patients; its diameter is 1.7 +/- 0.5 mm, and its takeoff angle is 154 degrees +/- 15 degrees , making the vein potentially accessible for cannulation.

CONCLUSIONS

Differences in CV anatomy that are related to either gender or coronary artery disease could have important practical implications during the left ventricular lead implantation. The anatomical features of the vein of Marshall make it a feasible potential conduit for epicardial LA pacing.