Studies of Left Atrial Pressure During Cardioplegia Produced by Profound Hypothermia Using the Closed Chest Technique

Profound hypothermia with prolonged circulatory arrest. An experimental study.

“…Lesage, Tsuchioka, Koie, and Young (1963), in another series of experiments in which animals were subjected to prolonged periods of profound hypothermia induced by a heart-lung machine, concluded that prolonged perfusion and prolonged hypothermia, particularly when flow was maintained at a high rate, might account for the lung damage. In a later series of experiments one of the present authors has subjected five dogs to profound hypothermia and prolonged perfusion using a heart-lung machine, and none developed pulmonary symptoms (Johnston, Nield, Pritchard, and Hercus, 1965). Further contradictory evidence in this regard is furnished by the absence of pulmonary complications in patients undergoing profound hypothermia for repair of a cerebral aneurysm.…”

Mechanisms determining the behaviour of the left atrial pressure during cardioplegia.

“…Earlier studies which we performed (Johnston, Nield, Pritchard, and Hercus, 1965), when direct measurement of the left atrial pressure was made using a modification of the Ross (1959) technique, showed that at normal flow rates of 60 ml./kg./ min., although the left atrial pressure rose, it did not reach dangerous levels. When the flow was artificially increased to 120 ml.…”

“…This latter state was considered to be one of the most potent causes of the perfusion lung syndrome in the early days of bypass. Nevertheless when this method is used to produce profound hypothermia when operating on intracranial aneurysms little difficulty is experienced in reversing ventricular fibrillation to sinus rhythm, and post-operatively cardiopulmonary difficulties are minimal (Patterson and Ray, 1962;Michenfelder, Kirklin, Uihlein, Svien, and MacCarty, 1964;Gonski, Johnston, Hercus, Rollison, and Nield, 1964;Gonski and Johnston, 1966).Earlier studies which we performed (Johnston, Nield, Pritchard, and Hercus, 1965), when direct measurement of the left atrial pressure was made using a modification of the Ross (1959) technique, showed that at normal flow rates of 60 ml./kg./ min., although the left atrial pressure rose, it did not reach dangerous levels. When the flow was artificially increased to 120 ml.…”

Closed-chest circulatory support by pump-oxygenator in experimental ventricular fibrillation at normal temperature.

“…Experimentally, Ross, Gilbert, Sharp, and Morrow (1958) in the open-chest animal, and more recently Patterson and Ray (1962) and Johnston, Nield, Pritchard, and Hercus (1965) in the closedchest animal, have pointed to the danger of high left atrial pressures developing during venoarterial bypass in the presence of cardiac arrest or acute left heart failure, due to the accumulating inflow of pulmonary, bronchial, and thebesian blood into the left heart. The left atrial pressure was more likely to rise if it was already high at the start of bypass (a strong possibility in acute left heart failure), and also if the circulatory support flow rate was high (as it may need to be at normal temperature if a reduction in the work load and oxygen consumption of the myocardium is desired (Salisbury, Bor, Lewin, and Rieben, 1959;Schenk, Delin, Camp, McDonald, Pollock, Gage, and Chardack, 1964)).…”