Echocardiographic evaluation of the heart in accidental hypothermia.

Echocardiographic study was performed in ten patients with accidental hypothermia to investigate the hypothermic effects on cardiac activities. The intervals from the onset of the posterior wall forward movement to the peak of the forward excursion (C-D interval) and from the peak of the forward excursion to the end of the early diastolic filling (D-F interval) were pro longed in hypothermia. The interval from the initial deflection of the QRS complex to the onset of the posterior wall forward movement (Q-C interval) was not prolonged. Maximal systolic and diastolic endocardial velocity was decreased in hypothermia. These abnormal findings were remarkable in mod erately deep hypothermia (<26•Ž), and returned toward normal as the body temperature rose. Stroke volume was low in three cases, while normal in others. The stroke volume did not change significantly as the body tempera ture rose. All these findings are similar to the data which have been obtained in experimental conditions. From these results, there seems to be a marked delay in the ability of the heart muscle to contract and relax in accidental hypothermia. This delay appeared to be produced mainly by hypothermia itself although many other factors must be considered to have influenced these results.