MECHANICAL HEART — GRIFFENHAGEN AND HUGHES 351 



School a father's own lung was used in conjunction with a pump 

 to bypass the heart of his 4-year-old daughter during intra- 

 cardiac surgery (Warden, Cohen, Read, andLillehei, 1954; Peters, 

 1954; Salisbury, 1954). Finally, in May 1955, Kirklin of the 

 Mayo Clinic in Rochester, Minn., reported several successful re- 

 pairs of septal defects in children using a modified Gibbon machine 

 (Kirklin, Du Shane, Patrick, Donald, Hetzel, Harshbarger, and Wood, 

 1956). 



Still a third procedure, called hypothermia, is proving somewhat 

 successful and encouraging for intracardiac operations. As early as 

 1950 a group at the University of Toronto suggested hypothermia for 

 carrying out cardiac surgery (Bigelow, Lindsay, and Greenwood, 

 1950; Bigelow, Callaghan, and Hopps, 1950). Normal body tem- 

 perature is 98.6° F. ; by chilling the patient as low as 78° F., the whole 

 life process is slowed down so that instead of only 2 or 3 minutes 

 while no blood is passing through the heart, the surgeon may have as 

 much as 8 minutes to work within the heart without damage to the 

 brain. On September 2, 1952, F. John Lewis and Mansur Taufic at 

 the University of Minnesota performed a successful operation on a 5- 

 year-old child with an atrial septal defect using hypothermia (Lewis 

 and Taufic, 1953) ; and between January 9 and July 9, 1953, Henry 

 Swan and associates at the University of Colorado performed opera- 

 tions on no less than 15 patients while they were in a hypothermic 

 state. In 13 of these patients, circulation was stopped for periods 

 varying from 2 to 8i/^ minutes, and the operation was performed on the 

 open heart under direct vision with only one operative death ( Swan, 

 Zeavin, Blount, and Virtue, 1953). 



"V^riiile the procedures of cross circulation and hypothermia are sig- 

 nificant advances, there is near unanimous agreement among thoracic 

 surgeons that the eventual answer to the problem of open cardiac 

 surgery is the temporary bypass of the heart using a mechanical pump 

 in association with a means of oxygenation (the patient's own lungs 

 or a mechanical oxygenator). True, the technical difficulties have 

 not yet been completely solved. Most mechanical hearts and/or heart- 

 lungs are expensive and complex requiring skilled persons to use them. 

 Their use materially increases the magnitude of an operation because 

 of the time required to attach the machine to, and later remove the 

 machine from, the patient's circulatory system. The blood of the 

 patient must be heparinized and its capacity to clot must be restored 

 with protamine. Hemolysis and air embolism are hazards in most 

 of the lieart-lung machines. The solutions to some of these problems 

 associated with extracorporeal circulation have already been found; 

 others will certainly be solved in time to come. 



All of this work with the mechanical heart is in its infancy. The results 

 demonstrated to date by the various investigators working in this field offer 



