Cardiorespiratory desynchronisation after acute myocardial infarction

The prognosis of cardiac diseases can be estimated from the variability of regulation parameters of the cardiovascular system. Changes in the variabil ity of a regulation parameter causes disturbances in the synchronisation of interacting control loops. Conclusions about the severity of the underlyin g functional impairment can be drawn from these disturbances. This study in vestigates the synchronisation of the control loops of the heart rate and r espiration (cardiorespiratory synchronisation, CRS) after acute myocardial infarction. We investigated 43 patients after myocardial infarction and 27 healthy cont rols. To quantify the CRS the synchronisation in phase of respiration and h eart rate was assessed. The heart rate variability (HRV) was also assessed. Patients after myocardial infarction have a significantly reduced HRV and CRS. There is a non-linear relationship between HRV and CRS. Patients with left ventricular enlargement and reduced left ventricular ejection fraction (less than or equal to 45%) significantly differed from the other infarct patients and controls in CRS but not in HRV. They had a marked degree of ca rdiorespiratory desynchronisation and were identified by a threshold value. CRS is a measure of the interaction of respiration control and heart rate c ontrol. After myocardial infarction, a reduction of the HRV can be observed . The desynchronisation of the control loops of respiration and heart rate especially appears in large infarcts. This can be quantitatively assessed b y the method presented.