Intensive home-based exercise training in cardiac rehabilitation increases exercise capacity and heart rate variability.

BACKGROUND: Reduced heart rate variability (HRV) is a risk factor for cardiac death. Animal studies have shown increased HRV and reduced mortality after physical training. We evaluated the change in exercise capacity and HRV in cardiac rehabilitation patients, randomised to routine or home-based intensive training. The design was prospective, stratified randomisation with pre-specified subgroup analysis. METHODS: Maximal bicycle exercise test and 24-h Holter were performed 1 (baseline), 4 and 12 months after myocardial infarction (MI) or coronary artery by-pass surgery (CABG). Patients were randomised to physical training either two (N) or six (I) times per week for 3 months Sixty-two patients (43 MI and 19 CABG patients) were evaluated. RESULTS: Exercise capacity increased significantly more after 3 months of training in group I (mean (S.E.)); 29.0 (3.4) vs. 7.2 (2.6) watts, P<0.001). One year later the difference in exercise capacity remained (26.5 (3.3) vs. 11.8 (3.8) watts, P<0.001). Global HRV measurements SDNN and SDANN increased significantly more in group I after training (17.1 (5.6) vs. 1.7 (3.7) and 16.2 (4.9) vs. 2.8 (3.1) ms, P<0.05) and 1 year later the differences were still significant. Subgroup analysis showed more pronounced HRV response in CABG than MI patients. CONCLUSION: Intensive exercise training in cardiac rehabilitation increases exercise capacity and global HRV, which could be of prognostic significance.

Long-term effect of endoscopic transthoracic sympathicotomy on heart rate variability and QT dispersion in severe angina pectoris.

UNLABELLED: We evaluated short and long-term effects on QT dispersion and autonomic balance after endoscopic transthoracic sympathicotomy (ETS). Heart rate variability (HRV) reflects autonomic balance of the heart. QT dispersion is a marker of cardiac electrical instability in patients with ischemic heart disease. Holter recordings for 24 h and a twelve-lead ECG were made prior to, 1 month, 1 year and 2 years after ETS. HRV was analysed in time domain and spectral analysis was performed during controlled respiration in supine position and during head up tilt. Dispersion of QT time and QTc were calculated. Of 88 patients, 62 (60) were eligible for HRV (QT-dispersion) analysis after 1 month, 39 (38) patients after 1 year and 23 (24) patients after 2 years. The HRV analysis showed a significant change of indices reflecting sympatho-vagal balance indicating significantly reduced sympathetic (LF) and increased vagal (HF, rMSSD) tone. These changes still persisted after 2 years. Global HRV increased over time with significant elevation of SDANN after 2 years. QT dispersion was significantly reduced 1 month after surgery and the dispersion was further diminished 2 years later. CONCLUSION: ETS changed HRV and QT dispersion which could imply reduced risk for malignant arrhythmias and death after ETS.

Effect of endoscopic transthoracic sympathicotomy on heart rate variability in severe angina pectoris.

Endoscopic transthoracic sympathicotomy (ETS) is a recently developed technique to divide sympathetic nerves. ETS has been shown to improve symptoms and reduce ischemia in patients with severe angina pectoris. Low heart rate variability (HRV) in patients with ischemic heart disease carries an adverse prognosis. HRV reflects autonomic response of the heart and a shift in the sympathovagal balance towards parasympathetic dominance could be a marker of improved prognosis. HRV might also be used as an indicator of surgical success in sympathetic heart denervation. Heart rate was recorded in 57 patients before and after ETS. Registration was recorded during controlled respiration in the supine position and at tilt test over 10 minutes and spectral analysis was performed. Twenty-four hour Holter recordings were analyzed in the time domain. During the controlled setting, the high-frequency (HF) component (0.15 to 0.40 Hz) increased significantly whereas the low-frequency (LF) component (0.04 to 0.15 Hz) did not change significantly. The LF/HF ratio at tilt test was reduced from 1.3 to 0.8 (p <0.01). The time-domain analysis showed a significant increase of the mean RR interval (923 to 1,006 ms, p <0.001) and indexes reflecting parasympathetic tone also increased significantly (the root-mean square of difference measured from 24.3 to 29.5 ms, p <0.001 and the proportion of adjacent RR intervals >50% measured from 5.5% to 8.2%, p <0.01), whereas measurements reflecting global HRV did not change. In addition to relief of symptoms and reduced ischemia in severe angina pectoris, ETS caused a shift of sympathovagal balance toward parasympathetic tone. This might explain the anti-ischemic effect and have prognostic implications.

Angina pectoris treated by thoracoscopic sympathecotomy.

Open surgical sympathectomy has previously been shown effective in relieving severe angina pectoris. The method was hampered by high morbidity and mortality. The authors have developed a minimally invasive technique of dividing only the sympathetic chain endoscopically and obtained good results with no serious complications in patients operated on for severe palmar hyperhidrosis. This method was used in 43 patients with severe angina pectoris who were not eligible for coronary artery bypass grafting or percutaneous transluminal coronary angioplasty. There was no mortality or any severe complications. Some 19 patients became symptom-free while 22 were improved and two unchanged after surgery. The frequency of anginal attacks was significantly reduced, as was the consumption of nitroglycerine tablets. The maximum exercise capacity was significantly increased and ST-segment depression reduced.

Endoscopic transthoracic sympathicotomy for severe angina.

We evaluated the antianginal effects of endoscopic transthoracic sympathicotomy (ETS) in 24 patients not eligible for coronary bypass surgery or angioplasty. In this procedure, the sympathetic chain is electrocoagulated under general anaesthesia. No major surgical complications occurred. The frequency of anginal attacks was significantly reduced (p = 0.001). The mean increase in maximum exercise capacity was 13 (SD 21) W (p = 0.009). ST depression at maximum comparable workload was reduced by 0.052 (0.10) mV (p = 0.005). Global ejection fraction during exercise and metaiodobenzylguanidine uptake were unchanged. Heart rate variability analysis showed a reduction of the ratio between low and high frequencies at tilt test (-1.00 [0.96]; p < 0.001). We conclude that ETS can be done without major complications, alleviates angina, and increases maximum working capacity in patients with advanced coronary disease.