Assessing Non-invasive Studies to Evaluate Resynchronization Pacing Effectiveness in the Young.

Appropriate non-invasive assessments (ECHO/ECG) of cardiac resynchronization pacing therapy (CRT) among younger patients (pts) with/without (w/wo) congenital heart disease (CHD) are not established. Ejection fraction (EF) and QRS can be unreliable due to anatomy, surgical repairs, and pre-existing pacemakers (PM). This study correlates updated non-invasive studies, including newer strain values, with clinical and invasive hemodynamic assessments of CRT response in the young. Sixteen pts (mean age 18.5 ± 6 years, 10/16 with pre-existing pacemakers) underwent CRT for heart failure (NYHA II-III). CHD included septal defects and Tetralogy of Fallot. Assessment of CRT efficacy was based on clinical findings, direct catheterization studies [pressures, contractility indices (dP/dt-max)], ECG changes, and ECHO studies [including updated global (GLS), left atrial strain (LAS), and sphericity indices] pre- and at 1-month and 1-year post-CRT. After 1 year following CRT, all pts improved (II-III to I-II) in clinical NYHA status. Contractility (dP/dt) increased (932 ± 351 vs 561 ± 178.7 mmHg-sec [p = 0.001]). QRS duration shortened only among pts with pre-existing PM (160 ± 25 vs 134 ± 25 ms [p = 0.02]). Standard ECHO parameters, including chamber dimensions and EF, showed no appreciable changes from pre-CRT values. However, endocardial GLS [(- 6.4 vs. - 9.6%) p = 0.0003] and LAS [(- 5.8 vs - 9.3%) p = 0.02] values significantly improved. Although CRT is applicable to younger pts, accurate non-invasive evaluations of response are lacking. This study establishes that newer strain values better correlate with clinical and hemodynamic changes over other parameters and offer more appropriate assessments of CRT response.

Ten-Year Clinical Experience with the Lumenless, Catheter-Delivered, 4.1-Fr Diameter Pacing Lead in Patients with and without Congenital Heart.

BACKGROUND: Patients with congenital heart defects (CHD) often present more challenges to pacing therapy due to anatomy than those without CHD. The lumenless, 4.1Fr diameter M3830 pacing lead (Medtronic, Inc., Minneapolis, MN, USA), approved for use in 2005, has, to date, reported to have excellent short-term (<6 years) lead performance. Unfortunately, very long-term performance is unknown, especially among CHD patients and with implants at alternate pacing (AP) sites. This study reports a 10-year clinical experience with the M3830 lead. METHODS: Records of patients who received the M3830 lead were reviewed: patient demographics, implant techniques and locations, sensing and pacing characteristics, impedances (Imp), and any complications at implant and follow-up. RESULTS: From 2005 to 2015, 141 patients (ages 2-50, mean 20.1 years, 57% males) received 212 leads: atrial 115; ventricle 97. CHD was present in 62% of patients. Leads were inserted at AP sites in 96% of patients. Postimplant follow-up was from 3 months to 10 years (mean 56.3 months). Comparative implant versus follow-up values (mean ± standard deviation) were available on 196 leads (92.5%), showing persistently low (<1 v @ 0.4-0.5 ms) pacing thresholds (P = 0.57). Sensing was also comparable (atrial leads, P = 0.41; ventricular leads, P = 0.9). Impedances differed (P < 0.05) but remained within the normal range. Two A leads became dislodged and one was repositioned while two other leads (1 A, 1 V) were extracted. There are no differences observed in the pacing characteristics between the CHD and non-CHD groups on follow-up. CONCLUSIONS: The 4.1Fr lumenless pacing lead shows ease of implant regardless of CHD or AP site, excellent very long-term (10 years) stability, and performance indices with a very low rate of complications.

Optimizing paced ventricular function in patients with and without repaired congenital heart disease by contractility-guided lead implant.

BACKGROUND: This study evaluates the concept of optimizing ventricular pacing in regard to functional cardiac response. Lead implant based on physiologic variables of contractility at various sites was performed in patients with and without congenital heart disease (CHD). Since right ventricular apical pacing may adversely alter contractility and myocellular function, septal and outflow tract pacing have been advocated. However, there are few studies in the young and essentially none in those with CHD. METHODS: A total of 113 consecutive patients with and without repaired CHD, aged two to 51 (median 16), some with preexisting epicardial pacemakers, underwent transvenous pacemaker implant using standard sensing/pacing indices plus measurements of pressures, QRS, and contractility responses at each of five predefined potential ventricular implant sites: apex, inflow-, low-, mid-, and infundibular/outflow-septal with each patient serving as his/her own control. Implant was at the site of best contractility with active-fixation, low-threshold steroid-eluting leads. RESULTS: Measured contractility indices varied up to 31% (mean 12%) between sites per patient. Septal regions (mid-, inflow-, and low-) were associated with the most optimal and right ventricular epicardial showed the worst contractility (P < 0.05) responses. Apex was optimal in some CHD patients. Threshold and sensing were comparable up to 11 years (mean 7) postimplant regardless of septal site. CONCLUSION: There is no single "sweet spot" for optimal ventricular pacing, and the best implant sites are patient and CHD variable. Current lead designs ensure chronic stability/performance regardless of site. Proactive contractility-guided pacing implant can optimize chronic paced ventricular function.

Comparative Chronic Valve and Venous Effects of Lumenless versus Stylet-Delivered Pacing Leads in Patients with and Without Congenital Heart.

BACKGROUND: Standard, 5-7-Fr diameter pacing leads (PLs) can adversely affect atrioventricular valve (AVV) and venous (superior vena cava [SVC], innominate [INN]) integrities. Although chronic pacing/sensing performances have been reported on the steroid-eluting, lumenless, 4.1-Fr PL (Model 3830, Medtronic Inc., Minneapolis, MN, USA), comparative valve and venous effects are largely unknown. METHODS: Patients (n = 134) were divided into two PL groups: Group 1 (n = 65, Model 3830) and Group 2 (n = 69, various 5-7 Fr models) and followed up to 9 years postimplant. Patient demographics, clinical findings, valve function, and venous dimensions were reviewed. Statistical significance was defined as P < 0.05. RESULTS: Patient implant age (mean 16.4 years vs 17.3 years), presence of congenital heart defect (CHD), and preexisting valve issues were comparable between groups. New or worsening valve insufficiency occurred in 12% of Group 1 patients (mean follow-up 4.3 ± 2.8 years) and 27% of Group 2 patients (mean follow-up 6.2 ± 3.5 years; P < 0.05). Significant SVC or INN narrowing was found in 11 % of Group 1 and 24% of Group 2 patients (P = 0.0004). All Group 1 patients <12 years of age showed normal while 50% of those from Group 2 exhibited stunted SVC or INN growth (P < 0.05). CONCLUSION: The lumenless, 4.1-Fr diameter PL offers improved clinical benefits, better AVV integrity, and venous development compared with larger 5-7-Fr diameter PL and should be considered especially in younger patients with/without CHD.

Performance of the lumenless 4.1-Fr diameter pacing lead implanted at alternative pacing sites in congenital heart: a chronic 5-year comparison.

PURPOSE: United States approval of the Model 3830, 4.1-French (Fr) diameter, lumenless, pacing lead (Medtronic Inc., Minneapolis, MN, USA) in patients under 17 years of age, and those with congenital heart disease (CHD), was in 2005. To date, long-term performance at alternative pacing sites (APS) is limited and chronic efficacy comparisons with more established leads is lacking. The purpose of this study was to evaluate these factors. METHODS: Implant and follow-up data on leads were compared: group 1 (non-3830 leads) and group 2 (Model 3830 leads). These included acute and chronic sensing and pacing, impedances, implant sites, and complications. Groups were compared using Fischer's exact test, paired, and nonpaired t-tests, with significance defined at P < 0.05. RESULTS: A total of 119 patients (ages 5-48 years) received 171 leads: group 1 (n = 80) and group 2 (n = 91). At implant, there were no differences in patient age, CHD, sensing, or pacing thresholds between groups. Implant lead impedances differed between groups but all were within normal values for each lead design. Chronic data showed no difference in sensing, pacing thresholds, or impedances. There were five (6%) early lead dislodgements in group 1 and one (1%) in group 2. APS were achieved in group 2 with mean 1.6 ± 1.3 minutes fluoroscopy time. CONCLUSION: The new 4.1-Fr lumenless lead shows similar performance indices to established leads even at APS, yet is thinner and achieves APS with technical ease, permitting more efficient chronic pacing in children and all patients with CHD.

16 Years of Cardiac Resynchronization Pacing Among Congenital Heart Disease Patients: Direct Contractility (dP/dt-max) Screening When the Guidelines Do Not Apply.

OBJECTIVES: The purpose of this study was to use direct cardiac resynchronization therapy (CRT)-paced contractility (dP/dt-max) response as a pre-implantation evaluation among patients with congenital heart disease (CHD) and follow clinical parameters and contractility indexes after CRT implantation. BACKGROUND: Patients with CHD often develop early heart failure with few therapeutic options, leading to heart transplantation (HT). Unfortunately, guidelines for CRT do not apply, and function evaluations by cardiac ultrasound are often inaccurate among CHD anatomies. Therefore, which CHD patients would benefit from CRT remains an enigma. METHODS: From 1999 to 2015, 103 CHD patients with New York Heart Association (NYHA) functional class II to IV were listed for HT; 40 patients on optimal medical therapy were referred for paced contractility response cardiac catheterization before CRT consideration. If dP/dt-max improved ≥15% from baseline, these "responders" were given the option of CRT with continued follow-up after implantation. RESULTS: Of 40 patients studied, 26 (65%) (age 22 ± 8.2 years; 9 of 26 [35%] single or systemic right ventricle; 17 of 26 [65%] with pacemakers) met criteria for possible hemodynamic benefit and underwent CRT implantation. All 26 patients improved in NYHA functional classification: 5 of 26 patients (19%) were later relisted for HT (4 to 144 months, mean 55 months) after CRT implantation, whereas 21 of 26 (81%) continued with improved NYHA functional class (12 to 112 months, mean 44 months) later. A repeat dP/dt-max study following long-term CRT showed stable function or continued contractility improvement. CONCLUSIONS: Heart failure is common among CHD patients, and therapies are limited. CRT guidelines do not address clinical and anatomic issues of CHD. Short-term paced contractility response testing identifies those CHD patients who are likely to respond to CRT regardless of anatomy.