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Query: UMLS:C0018801 (heart failure)
 72,216 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An analysis has been made of long-term ECG recordings in 11 patients, 9 men and 2 women, mean age 69 +/- 7 years, who were carrying ECG recording equipment at the time of sudden death. Nine patients had coronary heart disease, one patient a dilatative cardiomyopathy and another one a combined aortic valve defect. Seven patients had a history of syncope. All patients had signs of cardiac insufficiency (NYHA index 3.0 +/- 0.6, heart-thorax quotient 0.55 +/- 0.05). Sudden death occurred predominantly whilst resting. In one patient it was due to bradyarrhythmia, in 10 to tachyarrhythmia, mostly ventricular tachycardia (initial heart rate 198 +/- 43/min; n = 8) which degenerated into ventricular fibrillation. Atrial fibrillation was present in 8 patients at the time of sudden death. Premonitory warning arrhythmias were not consistently detectable: comparison of arrhythmias in the first and last hour showed significant increases only in single ventricular extrasystoles (135 vs. 278 VES/h, P less than 0.05), not however in repetitive arrhythmias. An R-on-T phenomenon, as trigger mechanism of ventricular tachycardia, occurred in 5 cases. A synopsis of the published reports on approximately 110 patients with sudden death during long-term electrocardiographic monitoring confirmed that acute death is caused by bradyarrhythmias in approximately 15% (17 patients), and by tachyarrhythmias in 85% (94 patients). An increase in ventricular arrhythmias in the hour prior to death was observed in about 50% of patients and the R-on-T phenomenon, as the initiating mechanism for ventricular tachycardia, in 42%.
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PMID:[Sudden cardiac death in long-term electrocardiography]. 241 Feb 15

We investigated cardio-respiratory coupling in patients with heart failure by quantification of bidirectional interactions between cardiac (RR intervals) and respiratory signals with complementary measures of time series analysis. Heart failure patients were divided into three groups of twenty, age and gender matched, subjects: with sinus rhythm (HF-Sin), with sinus rhythm and ventricular extrasystoles (HF-VES), and with permanent atrial fibrillation (HF-AF). We included patients with indication for implantation of implantable cardioverter defibrillator or cardiac resynchronization therapy device. ECG and respiratory signals were simultaneously acquired during 20 min in supine position at spontaneous breathing frequency in 20 healthy control subjects and in patients before device implantation. We used coherence, Granger causality and cross-sample entropy analysis as complementary measures of bidirectional interactions between RR intervals and respiratory rhythm. In heart failure patients with arrhythmias (HF-VES and HF-AF) there is no coherence between signals (p < 0.01), while in HF-Sin it is reduced (p < 0.05), compared with control subjects. In all heart failure groups causality between signals is diminished, but with significantly stronger causality of RR signal in respiratory signal in HF-VES. Cross-sample entropy analysis revealed the strongest synchrony between respiratory and RR signal in HF-VES group. Beside respiratory sinus arrhythmia there is another type of cardio-respiratory interaction based on the synchrony between cardiac and respiratory rhythm. Both of them are altered in heart failure patients. Respiratory sinus arrhythmia is reduced in HF-Sin patients and vanished in heart failure patients with arrhythmias. Contrary, in HF-Sin and HF-VES groups, synchrony increased, probably as consequence of some dominant neural compensatory mechanisms. The coupling of cardiac and respiratory rhythm in heart failure patients varies depending on the presence of atrial/ventricular arrhythmias and it could be revealed by complementary methods of time series analysis.
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PMID:Bidirectional Cardio-Respiratory Interactions in Heart Failure. 2955 23