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HRV Predict Heart Failure? added 3/09/01
The following abstract has 17 people dieing of heart failure while their hearts were being monitored. It appears that heart rate variability computed by the LifeWatch might allow prediction of heart failure - prior to sudden cardiac arrest
Arch Mal Coeur Vaiss 1997 Nov;90(11):1477-84
[Analysis of heart rate variability before and at the moment of cardiac death]. [Article in French]
Brembilla-Perrot B, Ross M, Jacquemin L, Beurrier D, Houplon P, Danchin N Service de cardiologie A, CHU Brabois, Vandoeuvre.
The study of heart rate variability is a new means of assessing autonomic nervous system function and the risks of cardiac and sudden death in patients with advanced cardiac disease.
The aim of this study was to analyze changes in heart rate variability in the hours preceding cardiac death and just before its occurrence. Seventeen subjects aged 78.5 +/- 10 years, with advanced cardiac disease responsible for a reduction of left ventricular ejection fraction below 40%, died during Holter ECG recording.
Ten died of ventricular fibrillation, 5 of bradycardia and 2 of non-rhythmic causes.
General analysis of heart rate variability showed a decrease in all but 1 patient, the average standard deviation of normal RR intervals in subjects in sinus rhythm being 53 +/- 14 msec and the fractioned spectral power (low frequency/high frequency power) being 1 +/- .07.
The change in heart rate variability did not allow prediction of the mechanism of death: the mean heart rate only increased before death in 3 of the patients with an ischaemic component in the hours before death, the indices of vagal tone were very low in the majority of patients and, just before death, a disequilibrium between the spectral powers with a sudden increase in LF/HF ratio of 10 of the 17 patients, irrespective of the cause of death, appeared.
In conclusion, a decrease in heart rate variability was observed in all cases but did not predict the mechanism of death. Just before death occurred, some patients, especially those with acute ischemia, showed a sudden change in the indices of heart rate variability indicating a terminal vaso-sympathetic disequilibrium.
The following abstract shows that after a MI, HRV can be used to estimate the possibility of subsequent sudden cardiac death.
Acta Univ Palacki Olomuc Fac Med 1998;141:69-73
Utility of short-term heart rate variability for prediction of sudden cardiac death after acute myocardial infarction.
Kautzner J, St'ovicek P, Anger Z, Savlikova J, Malik M
Department of Cardiology, Institute for Clinical and Experimental Medicine, Prague, Czech Republic.
Heart rate variability (HRV) computed from 24-hour ECG recording has been associated with an increased risk of malignant arrhythmias after MI. To make HRV analysis more practical, we evaluated prospectively prognostic role of short-term HRV in comparison with other risk stratifiers. Study population consisted of 48 patients with acute MI (mean age 59.6 +/- 10.6 years, 38 males), who were off betablockers. All patients underwent 30-minute ECG recording at supine rest on day 2 and 5 after admission, between 9 and 11 a.m. One ECG channel from a commercial bedside monitor was A/D converted, and subsequently analysed using a purpose-built interactive software. Short-term HRV was computed as the standard deviation of all normal-to-normal RR intervals (SDNN) as well as the square root of the mean of the sum of the squares of differences between adjacent normal RR intervals (rMSSD). Left ventricular ejection fraction (LVEF, in %) was determined using 2D-echocardiography. During one-year follow up, 5 patients (10.4%) died of sudden cardiac death (SCD) and one of non-cardiac death. Subjects who died of SCD presented with significantly lower SDNN parameter on day 5 (28.8 +/- 4.3 vs 39 +/- 18.4, p < 0.006) and similar trend was revealed for rMSSD (12.22.8 vs 24.321, N.S.). Similarly, LVEF was significantly decreased in these patients (35.4 +/- 5.5 vs 49.7 +/- 11.3, p < 0.007). Positive predictive accuracy for prediction of SCD was 17% for rMSSD, 20% for SDNN, 29% for LVEF, and 40% for combination of depressed SDNN (< or = 33 ms) and LVEF (< or = 40). In conclusion, depressed HRV computed from short-term predischarge ECG recordings obtained under standardised conditions is associated with an increased risk of SCD. Such predictive power is substantially increased in combination with depressed LVEF, and this approach seems to be effective as a simple screening method to identify high risk subjects.