Late stenosis of Starr-Edwards cloth-covered prostheses

During a two-year period (August, 1971, to July, 1973) 1 Starr-Edwards Model 2400 and 135 Starr-Edwards Model 2320 aortic prostheses were inserted without postoperative antiocagulant therapy. Seven of these valves (including the Model 2400 prosthesis) have been replaced because of substantial transvalvular gradients resulting from fibrous overgrowth of the valve orifice. Symptoms associated with aortic stenosis occurred an average of nine months after the initial operation. Six patients had severe anemia (packed cell volume less than 30%) and hemolysis (serum lactic dehydrogenase greater than 900 units). Gradients across the prostheses ranged from 66 to 105 mm Hg with a mean of 87 mm Hg. One valve was size 8A, 3 were 10A, and 1 was 12A. Fibrous ingrowth was not observed in an earlier group of 23 patients receiving the Model 2310 or Model 2320 prosthesis who were placed on long-term anticoagulant therapy. These findings, coupled with a 9% incidence of thromboembolism at one year, indicate that patients having these prostheses inserted should receive long-term anticoagulant therapy.

P waves during ectopic atrial rhythms in man: a study utilizing atrial pacing with fixed electrodes

Threshold bipolar pacing was performed from one of 12 selected atrial sites with temporary implanted electrodes in 69 patients following open-heart surgery in order to study P wave polarity and morphology and the P-R interval during paced ectopic atrial rhythms. A negative P wave was recorded in lead I only with pacing the left atrium and only when pacing near the left pulmonary veins. A positive bifid P wave in V1 was recorded only with left atrial pacing and only when pacing was near the inferior pulmonary veins and coronary sinus. P wave polarity and morphology were otherwise of no use in localization of the origin of the impulse in these studies. The pacing stimulus to P wave interval was found to vary between 10 and 54 msec, making the duration of the P-R interval an unreliable indicator of the site of origin of the paced impulse. Although the relation of these paced rhythms to spontaneously occurring ectopic rhythms is unclear, the previously published criteria for localizing ectopic atrial rhythms are again demonstrated to be unreliable. P wave polarity and morphology and the P-R interval are of limited value in ascertaining the origin of ectopic atrial rhythms in man.

Valve replacement and myocardial revascularization. Results of combined operation in 59 patients

Fifty-nine patients (mean age 57 years) underwent aortic valve replacement or mitral valve replacement combined with saphenous vein bypass grafting (39 single, 19 double, 1 triple) between May, 1970 and January, 1974. The hospital mortality for aortic valve replacement was 4.7% (2 of 43 patients) and for mitral valve replacement 6.3% (1 of 16 patients). There was a 21% incidence of postoperative myocardial injury in the patients with aortic valve replacement and a 6.2% incidence in the patients with mitral valve replacement. Variations in operative technique and in the methods of intraoperative myocardial preservation (coronary perfusion or profound hypothermic ischemic arrest) did not affect hospital mortality or the incidence of myocardial injury. Prolonged periods of ischemic arrest (greater than 50 minutes) were not used. The late mortality for aortic valve replacement was 16.3% (seven patients) and for mitral valve replacement 25% (four patients). There was symptomatic improvement in the majority of survivors. Operative mortality rates for the combined procedures are comparable to those from our institution for valve replacement alone.

Surgical versus medical treatment of occlusive disease confined to the left anterior descending coronary artery

The results of saphenous vein bypass grafting and medical treatment were compared in 53 patients with stable angina pectoris, high grade occlusive disease confined to the left anterior descending coronary artery and normal or minimally impaired left ventricular function. Survival, incidence of myocardial infarction, relief of angina and response to exercise testing were evaluated. In the 29 surgically treated patients, followed up a mean of 24 months, there were two late deaths (7 percent) and five myocardial infarctions (17 percent). Twelve patients (41 percent) were free of angina and the majority had increased exercise performance when tested up to 18 months postoperatively. In the 24 medically treated patients, there were no deaths and one myocardial infarction (4 percent) in a mean follow-up period of 37 months. Six patients (25 percent) were free of angina. Less improvement in exercise performance was observed than in the surgically treated group. This subset of patients with isolated left anterior descending coronary artery disease has a favorable prognosis that is not enhanced by bypass grafting. Surgical treatment is more effective than medical treatment in relieving angina and improving exercise performance in the early years after coronary arteriography.

Changes in grafted and nongrafted coronary arteries following saphenous vein bypass grafting

Progression of disease in the native coronary arterial circulation was studied in 121 patients who underwent saphenous vein bypass graft surgery at the University of Alabama Medical Center, Birmingham, between 1969 and 1972, and who had a second coronary arteriogram at a mean interval of 11.7 months later. Two hundred thirteen arteries (10 triple, 74 double, 37 single) were grafted and 148 were not. Graft patency rate was 72%. Stenotic obstructive lesions in defined arterial segments and major branches were recorded for each artery at each examination. Pre and postoperative arteriograms were reviewed at the same time. Disease was expressed as "% stenosis" of each segment or branch examined. An arterial score, which was the sum of segments and branches seen on each occasion, was calculated for each artery and the scores were compared. New total occlusion, new obstructive lesions, and progression of pre-existing lesions were five times more frequent in grafted than in nongrafted arteries with comparable initial disease. New and progressive lesions were encountered with the same frequency in arteries with patent and occluded grafts. They occurred more frequently in segments proximal to the graft than in distal segments. Arteries with moderate (less than 75%) and arteries with severe (75-99%) stenosis had similar progression rates. Only 2% of segments of ungrafted arteries showed new total occlusions as compared to 60% of grafted arteries. The arterial score fell by 34% in grafted arteries and did not change in nongrafted arteries. These findings suggest that significantly fewer branches and segments of grafted arteries are seen following bypass grafting. New totally occlusive lesions are considerably more frequent in grafted than in nongrafted arteries and are not related to graft patency at one year after surgery. Disease progression in ungrafted vessels is relatively slow. These changes in the coronary arteries should be considered when assessing patients, particularly those with moderate degrees of stenosis, for bypass grafting.

Coronary perfusion versus cold ischemic arrest during aortic valve surgery. A randomized study

Sixty-four randomized patients undergoing primary, isolated, scheduled, prosthetic aortic valve replacement were studied to determine the safety of coronary perfusion and mild hypothermia (31 patients) and of cold ischemic arrest (33 patients). Cardiac performance, metabolism, and isoenzyme release and the electrocardiogram were studied early postoperatively. No differences greater than expected by chance were found between the two groups; however, the difference between group means of several hemodynamic variables was significantly larger than experimental error. Combined abnormalities of creatine phosphokinase (CPK) and lactic dehydrogenase (LDH) heart-specific isoenzymes, indicative of myocardial necrosis, were found in 33 of 48 patients (68.7%) so studied. The incidence was similar in both study groups. In 14 of 52 (27%) patients with electrocardiographic studies, changes indicative of new infarction or ischemia were demonstrated, but no differences in incidence between the two groups of patients were found. In both groups the transmyocardial excess lactate immediately postoperatively was elevated, falling to near normal over the next 24 hours. Aortic crossclamp and cardiopulmonary bypass times were less by 27% and 21% respectively when cold ischemic arrest was used.

Surgical treatment of complex forms of transposition

In spite of the new knowledge developed in recent years surgical treatment for patients with complex forms of transposition of the great arteries remains suboptimal. This is because of the morbidity and mortality that have followed many of the corrective operations, and these are related chiefly to the basic malformation and its secondary effects. This review summarizes information about surgical treatment of such patients and comments upon some of the implications of this experience.

Estimation of stroke volume in the dog by a pulse contour method

A method for estimating the stroke volume (SV) from the systolic area of a single-channel record of the central aortic pressure has been tested in 12 anesthetized open-chest dogs. The formula used was SV = K·Psa·(1 + Ts/Td), where Psa is the area under the systolic part of the curve above end-diastolic pressure, Ts and Td are the durations of systole and diastole, respectively, and K is an arbitrary constant derived from measurement of an initial SV by electromagnetic flowmeter in each dog and used thereafter without change, in that dog. In the 12 dogs, 541 simultaneous determinations of SV by the pressure contour and electromagnetic flowmeter methods were compared under normal and altered circulatory conditions employing 12 different interventions. The total range of SV was 2.4 to 28.1 ml, of heart rate 35 to 207/min, and of mean arterial pressure 24 to 166 mm Hg. The overall correlation coefficient (r) was 0.928 with a regression line y = 1.04x + 0.21 ml (SE) of estimate, ±17.4%. Except for three sympathomimetic drugs, the r values for all other interventions ranged from 0.93 to 0.99. These observations compare favorably with those of previously reported pulse contour methods. The windkessel origin of the formula is noted, and a new derivation from a modification of the "water-hammer" equation is given.

Heterograft replacement of the mitral valve: clinical, hemodynamic, and pathological features

Seventeen patients had replacement of their diseased mitral valves with formalin-fixed, mounted porcine heterografts over a ten-month period with no operative or postoperative mortality.

Hemodynamic studies early after operation indicate that patients with heterograft mitral valves behave no differently than patients who have had replacement of the mitral valve with ball valves. The early postoperative myocardial dysfunction present after mitral valve replacement is probably not related to the presence of a caged ball or other such device in the left ventricle. Late hemodynamic studies in two patients have shown complete competence of the valves and minimal mean diastolic and absent end-diastolic gradients at rest between the left atrium and left ventricle.

Six of the valves became incompetent and were removed from 2 to 11 months after operation. Histological study of these valves suggests that the development of incompetence in five of them was related to absorption of muscle beneath the right coronary cusp with retraction of the tissues supporting this cusp and subsequent avulsion of the adjacent tissues from the supporting frame.

The 11 patients whose valves remain competent are all clinically improved 6 to 15 months after operation. There have been no thromboembolic complications in any of the patients although long-term anticoagulation has not been used.

The failure of the aortic valve heterografts mounted on rigid frames in this series appears related to mechanical stress resulting from imperfect coaptation of the valve cusps, either from resorption of heterograft tissue or improper mounting. Further studies are necessary to clarify these observations.

Automated treatment of critically ill patients following operation

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Operative therapy for femoral-popliteal arterial occlusive disease. A comparison of therapeutic methods

One hundred ninety-four patients underwent 222 operations for femoral-popliteal arterial occlusive disease between 1957 and 1965. The results of operative therapy employing synthetic bypass grafts, thromboendarterectomy, and autogenous saphenous veins were assessed by determining the accumulative patency rates for the three operative methods, the incidences of subsequent major amputations, and the degree of symptomatic relief (fig. 1, tables 9 and 10).

The 2-year accumulative patency rates for synthetic bypass grafts, thromboendarterectomy, and saphenous vein bypass grafts were 28%, 50%, and 63%, respectively (table 8). Subsequent major amputations were performed in 37%, 27%, and 12% of the extremities in the three groups. Improvement in symptoms occurred in 33%, 48%, and 73% of the patients in the respective groups.

When grouped according to severity of presenting symptoms and signs and the status of the arterial outflow by arteriography, patency rates were highest in the vein graft group and lowest in the synthetic graft groups. The patency rates after endarterectomy in those extremities with severe symptoms and poor arterial outflow tracts were similar to those of the synthetic graft group.