Article

Elective Cardiac Arrest by the Melrose Technic

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Abstract

INTRACARDIAC operations would be more easily performed if the heart could be arrested and restarted at will, and if the coronary blood flow could be stopped without damage to the myocardium during the period of arrest. Visualization would be excellent in the quiescent and dry heart, suturing would be much simpler, and air embolism could not occur. This objective has now been achieved in England through the efforts of Melrose, Dryer, Bentall, and Baker.1 The basic physiological observation was made by Ringer2 in 1883. Hooker3 in 1929 suggested that potassium chloride could be used to stop the heart when it is in a state of ventricular fibrillation, and he recommended using calcium chloride to restart the heart beat. Montgomery, Prevedel, and Swan4 used a similar technic to reverse fibrillation in hypothermic patients. In our experiments with dogs, we followed closely the technic of Melrose and associates in which diastolic asystole is induced with potassium citrate, and we have been able to confirm their results.

Technic

First, the dog is connected to the heart-lung machine, as described in the preceding article. While the machine is pumping oxygenated blood at a flow rate of 35 ml. per kg. of body weight per minute, the caval and the azygos veins are closed off. Then the aorta is cross-clamped with a ductus clamp 2 or 3 cm. above the heart. In dogs weighing up to 15 kg., 2 ml. of a 25 per cent solution of potassium citrate ( = ½ gm. =4.5 mEq.). . .


 

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