Potential prevention of pacing-induced heart failure using simple pacemaker programming algorithm.

INTRODUCTION: Right ventricular pacing (RVP) causes ventricular desynchronization and may lead to the development of heart failure (HF). Prolongation of atrioventricular delay (AVD) in DDDR pacemakers reduces unnecessary RV stimulation. The aim of the study was to verify the influence of RVP reduction on HF symptoms. METHODS: The study comprised 31 patients (17 men, mean age: 71.6 ± 8 yrs) with DDDR pacemaker implanted due to sinus node dysfunction (SND). At baseline, 28 patients did not present any symptoms of HF. Three patients were in NYHA class II. Patients were randomized either to 150 ms AVD or to minimizing right ventricular pacing (MRVP). Crossing over to the alternate mode took place after 4 months. Cardiopulmonary exercise test (CPX), echocardiography (ECHO) and BNP measurements were done before pacemaker implantation, after 4 and 8 months. RESULTS: The percentage of RVP was significantly higher in 150 ms AVD than in MRVP: 81.7 ± 22.6 versus 14.2±20.5%, P < 0.0001. Patients with 150 ms mode had worse CPX parameters than those with MRVP mode: peak oxygen uptake was 14.2±4.3 versus 19.9±6.3 ml/kg per min, P = 0.0001, higher BNP concentrations: 72.3±48.3 versus 49.4±43.9 pg/ml, P = 0.001 and worse left ventricle [LV] function: ejection fraction: 53.2±6.7 versus 57.3±5.5%, P < 0.0001; LV diastolic diameter: 4.86±0.52 versus 4.66±0.5 cm, P < 0.01. CONCLUSION: Predominant RVP in patients without symptoms of HF at baseline may be responsible for worse performance in cardiopulmonary exercise test, higher BNP concentrations and impairment of LV function. Specific DDDR pacemaker programming promotes intrinsic AV conduction and may prevent the development of pacing-induced HF.

Success rate of transvenous left ventricular lead implantation for cardiac resynchronisation therapy - recent experience of a single centre.

BACKGROUND: Implantation of a left ventricular (LV) lead for cardiac resynchronisation therapy (CRT) may be challenging. Wider use of various implantation techniques increases the success rate of CRT. AIM: Short-term analysis of the success rate of transvenous LV lead implantation for CRT. METHODS: All CRT procedures performed in 2009 with first-time LV lead implantation attempt were analysed in terms of efficacy, total number of procedures, procedure and fluoroscopy time, complications, and reinterventions. Final LV lead location and the number of tested sites were analysed. Complex procedures were defined and described. RESULTS: We studied 122 patients aged 67.6 +/- 10.6 years (98 males/80%) selected for CRT. The CRT implantation was an upgrade procedure in 17 patients. Fifty-six (46%) patients had coronary artery disease and 111 (91%) patients were in NYHA class III. The mean LV ejection fraction was 27% (range 10-35%). The implantation success rate was 97.5%. There were 87 (73%) CRT-D systems implanted and 32 (27%) CRT-P systems. Mean procedure time was 118 +/- 41 min, and fluoroscopy time was 15.9 +/- 12.1 min. An optimal location of the LV lead was achieved in 107 (90%) patients. More than one LV lead sites were tested in 42 (35.3%) patients. Complex procedures were performed in 4 (3.4%) patients. Early LV lead reintervention (< 30 days) was necessary in 10 (8.4%) patients (11 procedures), and epicardial lead placement was performed in one patient. The LV lead location in the antero-lateral branch demonstrated the lowest reintervention rate (1/22, 4.5%) v. other sites (great cardiac vein: 1/8, 12.5%, lateral branches: 9/86, 10.5%, p = NS). The LV lead-related reinterventions and initial procedure failure were associated with the upgrade procedures. No serious periprocedural complications were recorded. In one patient, the CRT system was explanted due to pocket infection. One patent died three months after CRT implantation due to progressive end-stage congestive heart failure. CONCLUSIONS: 1. In a tertiary centre, CRT implantation success rate is high and implantation procedures are safe. 2. Achieved LV lead location is optimal in a vast majority of patients. 3. We noted a significant rate of early reinterventions related to LV lead dislodgement. 4. The LV lead implantation failure and reinterventions occurred more frequently in subjects with upgrade- to-CRT procedures. A similar trend was also noted in patients after cardiac surgery. 5. In selected cases, advanced techniques must be used to achieve successful CRT implantation.

Impact of cardiac resynchronisation therapy on adaptation of circulatory and respiratory systems to exercise assessed by cardiopulmonary exercise test in patients with chronic heart failure.

BACKGROUND: Cardiac resynchronisation therapy (CRT) has become a valuable therapeutic tool in patients with advanced chronic heart failure (CHF). The search for optimal methods for the assessment of CRT efficacy is still underway. AIM: To evaluate the impact of implantation of CRT devices in patients with CHF on adaptation of circulatory and respiratory systems to maximal exercise assessed by cardiopulmonary exercise tests (CPX) and 6-minute walking tests (6MWT). METHODS: We investigated 27 patients (22 males, 5 females, 61.2+/-9.1 years) with a CRT device implanted due to advanced CHF, which resulted from ischaemic or dilated cardiomyopathy. All patients before implantation underwent echocardiography, CPX with expired gas analysis and 6MWT. Investigations were repeated at 3-6 months after CRT implantation. In CPX we evaluated peak oxygen uptake (peak VO2), oxygen pulse, maximal minute ventilation-carbon dioxide production (VE/VCO2 (max)), and its slope (VE/VCO2 slope) and VE/VO2 slope, VO2 in anaerobic threshold (AT), and cardiac and respiratory reserve. In 6MWT we evaluated walking distance and heart rate and blood pressure response to exercise. RESULTS: We noted statistically higher mean peak VO2 after CRT implantation in the studied group: 11.34+/-3.38 vs. 14.56+/-3.99 ml/kg/min (p<0.0001) and 1.01 +/-0.44 vs. 1.4+/-0.55 l/min (p=0.003) and higher values of expired CO2: 1.00+/-0.43 vs. 1.43+/-0.67 l/min (p=0.004). The O2 pulse rose from 9.65+/-3.39 to 13.23+/-5.43 ml/beat (p=0.015). We also observed a significant reduction of VE/VCO2 slope from 42.34+/-13.35 before CRT to 34.77+/-6.04 after CRT (p=0.0196) and a significant decrease of VE/VO2 slope from 41.32 +/-15.46 to 34.01+/-6.27 (p=0.037). VE/VCO2 (max) fell from 58.02+/-15.86 to 50.1+/-13.14 (p=0.009). Patients estimated their dyspnoea on the Borg scale at peak exercise at 4.75+/-0.75 points before CRT and at 3.67+/-1.15 points (p=0.002) after CRT. Patients could walk a longer distance during 6MWT than before CRT (367+/-154.9 vs. 231.1+/-170.3 m, p<0.001). CONCLUSIONS: Cardiac resynchronisation therapy improves exercise tolerance measured by means of CPX and 6MWT, improves respiratory system efficiency and restores its adaptive mechanisms during exercise in patients with advanced CHF. Better exercise adaptation after CRT may be objectively measured with CPX parameters, and correlates with improvement of clinical symptoms. CPX seems to be a very helpful tool in assessing the results of CRT.