Autonomic modulation and clinical outcome in patients with chronic heart failure.

OBJECTIVE: Several studies documented the relevance of autonomic activity in the pathophysiology of heart failure. In our study we evaluated the adjustment of this activity under different stimuli, by means of heart rate variability (HRV), and correlated these findings with long-term mortality and sustained VT occurrence. PATIENTS AND METHOD: Fifty-three patients (mean age 54+/-9 years) with heart failure were submitted to time and frequency domain HRV analysis. This latter analysis was performed at rest, during paced breathing and during passive tilt. RESULTS: Lower standard deviation of RR intervals (76.76+/-24 versus 107.70+/-43, p=0.02), mean of the 5-min standard deviations of RR intervals (35.14+/-15 versus 62.39, p<0.01), standard deviation of the 5-min average RR intervals (69.42+/-19 versus 91.79+/-30, p=0.02), and baseline Low-Frequency (LF) power (15.15+/-12 versus 40.39+/-24 nu, p=0.001) characterized patients who died. Paced breathing induced a significant reduction of LF (40.39+/-24 to 20.12+/-18 nu, p<0.0001) and increase of High Frequency power (HF) (47.31+/-23 to 70.63+/-16 nu, p<0.0001) in survivors, while tilting induced a reduction of HF (47.31+/-23 to 29.80+/-16 nu, p<0.0001). Patients who died did not show significant variation of HRV neither during paced breathing nor during tilt. Reduced time domain indexes were significantly correlated to sustained VT occurrence. CONCLUSIONS: Patients with heart failure with a better prognosis are characterized by a responsiveness of autonomic modulation. Simple maneuvers, such as tilting and paced breathing, seem to provide more useful information, than the baseline evaluation of autonomic status, in identifying patients with a higher mortality. Time domain analysis was more helpful to estimate arrhythmic risk.

New advances in dynamic cardiomyoplasty: Doppler flow wire shows improved cardiac assistance in demand protocol.

No data have been published on real cardiac assistance with demand dynamic cardiomyoplasty. We tested the utility of a Doppler flow wire in measuring beat by beat aortic flow velocity and evaluating cardiac assistance in demand cardiomyoplasty patients. The technique was tested in seven patients (M/W = 6/1; age, 57.1+/-6.2 years; atrial fibrillation/ sinus rhythm = 1/6; New York Heart Association [NYHA] classification = 1.4+/-0.5). Measurements were done using a 0.018 inch peripheral Doppler flow wire advanced through a 5 French arterial femoral sheath. Three 1 minute periods with the stimulator off, and three 1 minute periods with clinical stimulation were recorded. We measured peak aortic flow velocity in all beats. Latissimus dorsi mechanogram was simultaneously recorded. Comparison between preoperative and follow-up data showed significantly higher values of tetanic fusion frequency and ejection fraction at follow-up, whereas mean NYHA class was significantly lower. Statistical analysis showed an increase in aortic flow velocity not only in the assisted versus rest period, but also in assisted versus unassisted beats (8.42+/-6.98% and 7.55+/-3.07%). A linear correlation was found between increase in flow velocity and latissimus dorsi wrap tetanic fusion frequency (r2 = 0.53). In demand dynamic cardiomyoplasty, systolic assistance is significant and correlated to the latissimus dorsi speed of contraction; a demand stimulation protocol maintains muscle properties and increases muscle performance.

Cardiovascular risk during physical activity in the mountains.

OBJECTIVE: Several previous studies evaluated the cardiovascular risk associated with exercise, but only a few papers considered this risk during physical activity in the mountains. The aim of this study was to assess the cardiovascular risk in a population practising physical activity in the mountains. METHODS: We used an observational study design. We estimated the population by integrating the data of presences in the accommodation establishments with data from telephone and on-field interviews. As survey sources of cardiovascular events we used the reports of the Mountain Rescue teams and of the emergency physicians and pathologists operating in the hospitals of the considered mountain area. RESULTS: We estimated that the duration of exposure to risk for the study population was, averagely per year, 12 449 877 person-days. During the study period, we recorded 117 cardiovascular events, namely 38 sudden cardiac deaths, 13 acute coronary syndromes, and five strokes. The remaining 61 events were non-traumatic events with a probable cardiovascular origin. We calculated one cardiovascular event per 319 000 person-days of physical activity in the mountains, one sudden cardiac death per 980 000 and one acute coronary syndrome per 2 895 000 person-days. CONCLUSIONS: The risk of cardiovascular events in the population practising physical activity in the mountains is very low and essentially limited to men over the age of 40, particularly if they do not practise regularly physical activity. For these subjects the risk seems to be associated with physical activity, but not with altitude and other typical aspects of mountains, such as low temperature and difficulties of terrain.