Balloon‐Facilitated Delivery of a Left Ventricular Pacing Lead

While modern implant tools have contributed greatly to the success of cardiac resynchronization therapy, technical challenges remain. A common problem is the inability to advance left ventricular pacing leads into branch veins that are tortuous or arise at steep angles. In these cases, advancement of the lead causes it to buckle and prolapse into the coronary sinus or great cardiac vein. Lead prolapsed can be avoided by employing a balloon to temporarily obstruct the coronary sinus or great cardiac vein just upstream from the branch vein. The balloon redirects the force of advancement laterally into the branch vein, facilitating delivery. (PACE 2013; 36:e31–e34)     

Abolition of Diaphragmatic Pacing by Nonsurgical Retraction of a Left Ventricular Lead

This report describes the nonsurgical elimination of intractable diaphragmatic stimulation by partial withdrawal of a left ventricular (LV) pacing lead (in the coronary venous system) with resultant preservation of LV pacing. The procedure entailed the use of a deflectable catheter in the right atrium for ensnaring the LV lead. At the 3-month follow-up, the absence of diaphragmatic stimulation was associated with a satisfactory LV pacing threshold and dramatic clinical improvement from effectual biventricular pacing.     

Usefulness of a Pacing Guidewire to Facilitate Left Ventricular Lead Implantation in Cardiac Resynchronization Therapy

Background: Intraoperative measurements of left ventricular (LV) pacing and sensing values were assessed using a novel 0.014-inch guidewire (Visionwire^®, Biotronik GmbH, Berlin, Germany) enabling pacing and sensing at the distal tip before final LV lead implantation .
Methods: Twenty-two consecutive patients selected for cardiac resynchronization therapy were studied .
Results: Significant correlation was found between the LV pacing threshold as assessed by the Visionwire^® and values after final LV lead implantation (r = 0.92, P < 0.001). Correlation for LV sensing was also significant (r = 0.72, P < 0.001). No significant correlation was present with respect to phrenic nerve stimulation. However, no phrenic nerve stimulation at 10 V/0.5 ms using the Visionwire^® identified 88% of patients without phrenic nerve stimulation at 10 V/0.5 ms with subsequent LV lead measurements .
Conclusion: This technique may facilitate transvenous LV lead implantation by preventing implantation in a unsuitable target vessel with respect to pacing and sensing values or phrenic nerve stimulation, thereby reducing procedure and fluoroscopy time .     

Long-Term Performance of the Attain Model 4193 Left Ventricular Lead

Background: Cardiac resynchronization therapy (CRT) has proven to be a valuable therapy addition for patients with drug-refractory heart failure and a ventricular conduction delay. Delivery of CRT is dependent upon the successful implantation and chronic performance of a left ventricular (LV) pacing lead. This study assessed the long-term electrical performance and safety of a steroid-eluting, transvenous, over-the-wire, cardiac vein pacing lead.
Methods: The Attain Model 4193 LV lead (Medtronic, Inc, Minneapolis MN, USA) was successfully implanted in 1,070 patients with 286 patients completing 3 years of follow-up. Clinical data were collected at pre-implant, implant, and at 6-month intervals for 3 years.
Results: Over 3 years, the mean chronic pacing threshold ranged from 1.9 V to 2.1 V, the mean R-wave sensing amplitudes ranged between 13.6 mV and 15.0 mV, and the mean pacing impedance ranged between 562 ohms and 590 ohms. Additionally, the observed freedom from first post-implant LV-lead-related complications was 90.4%. Of 1,070 total patients, 82 experienced 89 LV-lead-related adverse events requiring invasive interventions or resulting in the termination of the CRT therapy. The LV lead was repositioned in 31 patients, replaced in 21 patients, and explanted/capped in four patients. There were no deaths related to the LV lead during implantation or during the follow-up period.
Conclusions: The data suggest that the 4193 LV lead is safe and effective over time. The LV lead electrical measurements remained stable through follow-up, demonstrating reliable long-term performance within the recommended value range at 36 months and had an acceptable complication rate.     

A New Endocardial "Over-the-Wire" or Stylet-Driven Left Ventricular Lead:

Transvenous left ventricular (LV) leads are primarily inserted "over-the-wire" (OTW). However, a stylet-driven (SD) approach may be a helpful alternative. A new polyurethane-coated, unipolar LV lead can be placed either by a stylet or a guide wire, which can be inserted into the lead body from both ends. The multicenter OVID study evaluates the clinical performance of this new steroid- and nonsteroid eluting lead. The primary endpoint is the LV lead implant success rate after identification of the coronary sinus (CS). Secondary endpoints include complication rate, short- and long-term lead characteristics, overall procedure and LV lead placement duration, total fluoroscopy time, and lead handling characteristics ratings. To date, 96 patients with heart failure (68 ± 9 years old, 76% men) are enrolled. The CS was identified in 95 patients and, in 85 (88.5%), the LV lead was successfully implanted. The final lead positioning was lateral in 41%, posterolateral in 35%, anterolateral in 18%, and great cardiac vein in 6% of patients. In 70%, the 85 successful implantations, both stylet-driven and guide-wire techniques were used, a stylet only was used in 22%, and a guide wire only in 8%. Mean overall duration of 85 successful procedures was 112 ± 40 minutes, total fluoroscopy time 28 ± 15 minutes, and the duration of LV lead placement was 35 ± 29 minutes. During a 3-month follow-up, the loss of LV capture occurred in three and phrenic nerve stimulation in six patients. The mean long-term pacing threshold is 0.8 V/0.5 ms and pacing impedance is 550 Ω. The OVID data suggest that these new leads are safe and effective. The choice of both OTW and SD techniques during lead implantation offers greater procedural flexibility.     

Is the Left Ventricular Lateral Wall the Best Lead Implantation Site for Cardiac Resynchronization Therapy?

GASPARINI, M., et al .: Is the Left Ventricular Lateral Wall the Best Lead Implantation Site for Cardiac Resynchronization Therapy? Short-term hemodynamic studies consistently report greater effects of cardiac resynchronization therapy (CRT) in patients stimulated from a LV lateral coronary sinus tributary (CST) compared to a septal site. The aim of the study was to compare the long-term efficacy of CRT when performed from different LV stimulation sites. From October 1999 to April 2002, 158 patients (mean age 65 years, mean LVEF 0.29, mean QRS width 174 ms) underwent successful CRT, from the anterior (A) CST in 21 patients, the anterolateral (AL) CST in 37 patients, the lateral (L) CST in 57 patients, the posterolateral (PL) CST in 40 patients, and the middle cardiac vein (MCV) CST in 3 patients. NYHA functional class, 6-minute walk test, and echocardiographic measurements were examined at baseline, and at 3, 6, and 12 months. Comparisons were made among all pacing sites or between lateral and septal sites by grouping AL + L + PL CST as lateral site (134 patients, 85%) and A + MC CST as septal site (24 patients, 15%). In patients stimulated from lateral sites, LVEF increased from 0.30 to 0.39   (P < 0.0001)   , 6-minute walk test from 323 to 458 m   (P < 0.0001)   , and the proportion of NYHA Class III–IV patients decreased from 82% to 10%   (P < 0.0001)   . In patients stimulated from septal sites, LVEF increased from 0.28 to 0.41   (P < 0.0001)   , 6-minute walk test from 314 to 494 m   (P < 0.0001)   , and the proportion of NYHA Class III–IV patients decreased from 75% to 23%   (P < 0.0001)   . A significant improvement in cardiac function and increase in exercise capacity were observed over time regardless of the LV stimulation sites, either considered singly or grouped as lateral versus septal sites. (PACE 2003; 26[Pt. II]:162–168)     

Single Site Left Ventricular Pacing induced Dyssynchrony and Cardiomyopathy

Single site left ventricular (LV) pacing in the absence of intrinsic ventricular activity can be as detrimental to LV function as right ventricular apical pacing. This report describes a patient with complete heart block who developed significant dyssynchrony and cardiomyopathy secondary to single site lateral LV pacing. The process was reversed by placement of a second anterior LV lead. (PACE 2013; 36:e35–e37)     

Beneficial Effects of Biventricular Pacing in Patients with a "Narrow" QRS

GASPARINI, M., et al .: Beneficial Effects of Biventricular Pacing in Patients with a "Narrow" QRS. Congestive heart failure (CHF) patients with LBBB and QRS duration >150 ms are considered the best candidates to biventricular pacing (Biv-P). However, patients with a narrow (120–150 ms) QRS may also benefit from Biv-P since true ventricular dyssynchrony may be underestimated by considering only QRS enlargement. From October 1999 to April 2002, 158 CHF patients (121 men, mean age 65 years, mean LVEF 0.29, mean QRS width 174 ms) underwent successful Biv-P implantation and were then followed for a mean time of 11.2 months. According to basal QRS duration, patients were divided in two groups, with wide QRS (≥150 ms, 128 patients, 81%) and with narrow QRS (<150 ms, 30 patients, 19%). In the wide QRS group, LVEF improved from 29% to 39% (P < 0.0001), 6-minute walk test from 311 to 463 m (P < 0.0001), while NYHA Class III–IV patients decreased from 86% to 8% (P < 0.0001). In the narrow QRS group LVEF improved from 30% to 38% (P < 0.0001), 6-minute walk test from 370 to 506 m (P < 0.0001), and NYHA Class III–IV patients decreased from 60% to 0% (P < 0.0001). The data showed that in wide and narrow QRS patients, Biv-P significantly improved clinical parameters (NYHA class, 6-minute walk test, quality-of-life, and hospitalization rate) and main echocardiographic indicators. Furthermore, narrow QRS patients had a better survival rate, rapidly regained left ventricular function, and only a few patients remained in a higher NYHA class during follow-up. These patients should not be excluded "a priori" from cardiac resynchronization therapy. (PACE 2003; 26[Pt. II]:169–174)     

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.     

Seven Years of Left Ventricular Pacing Due to Malposition of Pacing Electrode

The case report is presented of a patient in whom an uncomplicated left ventricular transvenous pacing produced right bundle branch block (RBBB). A diagnostic echocardiography, confirmed by cine cardiovascular computed tomography, showed that there was no rupture of the right ventricle and diagnosed a left ventricular pacing, due to malposition of the pacing electrode. The patient was treated with aspirin and dipyridamole during the last 6 years of follow-up, without any complications, including 1 year of pacing, prior to admission.     

Ventricular Activation Onset-Triggered Left Ventricular Pacing:

Ventricular activation onset-triggered (VAOT) left ventricular pacing modalities synchronize left ventricular paced activation with existing intrinsic ventricular activation, in patients with complete LBBB and adequate rate. The purpose of this study was to evaluate the safety and feasibility of VAOT pacing with one left ventricular pacing lead, during temporary pacing in the postoperative period following open heart surgery. VAOT pacing was studied in five patients with LBBB and two patients with previously implanted right ventricular pacemakers. The VAOT pacing system used was assembled by modifying the function of existing equipment and its programming is described in detail. Comparative ECGs are reported, documenting the changes in ventricular activation produced by VAOT pacing. Stability of surface ECG acquisition was found to be essential to the success of temporary VAOT pacing and inappropriate pacing due to ECG instability is described. Patients were studied at rest and none experienced congestive heart failure. In the comparison of cardiac output, with and without VAOT pacing, no significant differences were found in LBBB patients or those with right ventricular pacemakers. In the comparison of arterial pressure, with and without VAOT pacing, no significant differences were found in six patients, however, in one LBBB patient with intrinsic predominant ventricular trigeminy, VAOT pacing was observed to have an antiarrhythmic effect resulting in suppression of ventricular ectopy and stabilization of arterial pressure. All patients survived VAOT pacing and the postoperative period without complications requiring additional intervention or treatment. (PACE 2004; 27[Pt. I]:730–739)     

Biventricular Pacing via a Persistent Left Superior Vena Cava: Report of Four Cases

GASPARINI, M., et al .: Biventricular Pacing via a Persistent Left Superior Vena Cava: Report of Four Cases. Persistence of left superior vena cava (LSVC) is an uncommon finding during pacemaker implantation, which may be particularly relevant in performing LV transvenous pacing. Rarely, it is further complicated by the presence of atresia of the coronary sinus ostium (CSO). This article reports the authors experience with biventricular pacing (Biv-P) in this unusual clinical setting. From October 1999 to April 2002, 158 patients underwent biventricular pacing. In four of them (mean age 62.2 years), the presence of a persistent LSVC draining into the coronary sinus (CS) was detected at implantation, associated with atresia of the CSO in two patients. A common characteristic was the angiographic finding of a large CS with few tributaries. The LV leads were successfully positioned in the middle cardiac vein in three patients and in a posterolateral vein in one patient. All vessels were large and their cannulation via downstream CS catheterization required the lead to be manipulated through sharp angles. Mean fluoroscopic exposure and procedural times were not significantly different from the overall Biv-P population. In all patients, at a mean follow-up of 11 months, sensing and capture threshold remained stable and a significant decrease in NYHA functional class and increase in LVEF were noted. The direct lead placement in large CS tributaries in the presence of persistent LSVC was feasible and safe. The leads remained stable up to a mean follow-up of nearly 1 year. (PACE 2003; 26[Pt. II]:192–196)     

A Method for Permanent Transvenous Left Ventricular Pacing

LV-based pacing has recently been reported to be of benefit in patients with severe cardiac failure and left bundle branch block. LV permanent pacing has been reported using epicardial leads but the surgical mortality is excessive. A transvenous approach is now favored. In this regard, cannulation of the coronary sinus and of one of its tributaries using only the permanent electrode is feasible but technically challenging. We describe a "long guiding sheath" method using catheterization, and a long radiopaque and peelable sheath. Once the coronaiy sinus is cannulated with the electrophysiological catheter, the long sheath is advanced to the mid-part of the coronary sinus. The permanent pacing electrode is then placed through the sheath and into a tributary of the coronary sinus. This method has been attempted in 10 patients and was successful in 8, with an average lead insertion time of 21 ± 5.5 minutes and an average fluoroscopic time of 11 ± 5.5 minutes. In conclusion, although transvenous left ventricular pacing remains a challenge, the "long guiding sheath" approach appears to facilitate this procedure with both a high success rate and an acceptable procedure time.     

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 Ω. 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.     

Is Right Ventricular Outflow Tract Pacing an Alternative to Left Ventricular/Biventricular Pacing?

The right ventricular apex has been used as the traditional pacing site since the development of transvenous pacing in 1959. Some studies suggest that pacing the right ventricular apex may cause remodeling and is harmful. In the past decade, there have been a multitude of studies of the hemodynamic, electrophysiological, electrocardiographic, and clinical effects of ventricular pacing at other sites. Pacing of the left ventricle singly or with biventricular pacing has emerged as an effective and safe therapy for moderate to severe congestive heart failure in patients with prolonged QRS complexes. Studies of alternate right ventricular sites, like the right ventricular outflow tract, have given mixed results. Not all patients can be treated with left ventricular pacing, which is a time-consuming and difficult procedure. Right ventricular pacing is easier and less expensive than left ventricular pacing and further study of additional right ventricular sites seems warranted. (PACE 2004; 27[Pt. II]:871–877)     

Similar Long-Term Benefits Conferred by Apical Versus Mid-Septal Implantation of the Right Ventricular Lead in Recipients of Cardiac Resynchronization Therapy Systems

Introduction: The benefits conferred by cardiac resynchronization therapy (CRT) are markedly influenced by the left ventricular (LV) lead placement. Little is known regarding the optimal right ventricular (RV) stimulation site.
Study Objective: To compare the long-term outcomes of CRT in patients with RV leads placed in the mid-septal region versus the apex.
Methods and Results: This nonrandomized, observational study included 117 patients with standard indications for CRT. The LV lead was implanted on the postero-lateral or lateral LV wall, while the RV lead was implanted at the apex (n = 82) or in the mid-septum (n = 35). Both groups were similar with respect to baseline clinical, demographic, and echocardiographic characteristics. After 12 months of CRT, the rates of clinical response to CRT were similar in both groups (63% vs. 66%), and similar degrees of reverse LV remodeling and LV resynchronization were observed on echocardiography and color tissue Doppler imaging. A ≥30% relative increase in LV ejection fraction (EF) occurred in 76% of patients in the RV apex group, versus 49% of patients in the RV mid-septum group (P = 0.05). A ≥45% left ventricular ejection fraction (LVEF) was measured at 12 months in 40% of patients in the RV apex group, versus 31% in the RV mid-septum group (ns).
Conclusions: RV mid-septal stimulation was not associated with a higher rate of response to CRT or greater improvement in LV function compared to RV apical stimulation.     

Acute Left Ventricular Dyssynchrony Improvement Predicts Long-Term Benefit from Cardiac Resynchronization Therapy

Study Objective: To evaluate the relationship between acute response to cardiac resynchronization therapy (CRT) and long-term clinical outcome in patients with drug refractory heart failure.
Methods and Results: In 28 patients undergoing CRT implant, left ventricular (LV) dyssynchrony was evaluated by tissue Doppler imaging (TDI)-derived longitudinal strain by mean of septum-lateral basal asynchrony index (S-Li) and basal delayed longitudinal contraction (DLC). TDI measurements were made before, and 30 minutes and 1 year after implant. Baseline and 1-year follow-up New York Heart Association (NYHA) functional class, 6-minute walking test (6-MWT) distance, and quality of life (QoL) score were measured. Responders (n = 22) were defined by a ≥ 1 decrease in NYHA functional class and 6-MWT ≥25% at 1 year. At baseline, no differences were observed between responders and nonresponders in clinical and echocardiographic measurements. LV dyssynchrony acutely recovered only in responders 30 minutes after implantation, with a significant reduction in S-Li and DLC. Moreover, the percent decreases in S-Li and DLC were highly correlated with those observed in NYHA class (r = 0.70, and r = 0.81, respectively, P < 0.001), 6-MWT (r = 0.59, and r = 0.57, respectively, P < 0.001 and P < 0.01), and QoL score (r = 0.71, and r = 0.83, respectively, p < 0.001) at 1-year follow-up.
Conclusions: Acute recovery of LV intraventricular dyssynchrony is a major discriminator between responders and nonresponders to CRT, which strongly correlates with a favorable long-term clinical outcome.     

Serial Changes in Right Ventricular Apical Pacing Lead Impedance Predict Changes in Left Ventricular Ejection Fraction and Functional Class in Heart Failure Patients

Pacing impedance has been proposed to monitor the clinical status of patients with congestive heart failure (CHF). This study examined whether changes in right ventricular (RV) pacing impedance correlate with changes in left ventricular ejection fraction (LVEF) and New York Heart Association (NYHA) functional class during long-term follow-up in pacemaker recipients with CHF. The study included 67 patients, 70 ± 12 years of age, in NYHA class II or III, and with a mean LVEF = 29 ± 8% at implant. LVEF, NYHA class, and bipolar pacing impedance at the RV outflow tract (RVOT) and apex (RVA) were measured at implant and at 3, 6, 9, and 12 months of follow-up. At implant, impedance was similar in RVOT (548 ± 115 Ω) and RVA (571 ± 174 Ω). Between implant and 3 months, mean impedance decreased (P < 0.0001) at both the RVOT (472 ± 62 Ω) and RVA (488 ± 86 Ω), LVEF increased (43 ± 14%, P < 0.0001), and the NYHA class decreased from 2.4 ± 0.5 to 2.1 ± 0.6 (P = 0.0001). Changes in RVA impedance correlated with changes in LVEF (r = 0.45, P = 0.002). A 50 Ω decrease in RVA impedance corresponded to a 3% decrease in LVEF. RVA impedance decreased significantly as NYHA class increased from I to IV (P = 0.04). There was no correlation between impedance measured at the RVOT and LVEF or NYHA class. A decrease in bipolar pacing impedance at the RVA was associated with worsening LVEF and the NYHA class. The use of pacing impedance to monitor the clinical status in CHF is dependent on the RV pacing site.