Edward A. Rittenhouse

Healing Basis and Surgical Techniques for Complete Revascularization of the Left Ventricle Using Only the Internal Mammary Arteries

Long-term follow-up data from several leading centers concerning patients undergoing coronary artery bypass clearly demonstrate the superiority of the internal mammary artery (IMA) with patency rates of 83 to 94% at 7 to 12 years compared with the saphenous vein and its patency rates of 41 to 53%. Our experimental studies provide a biological basis for understanding this difference. Thin-walled arterial autografts undergo no histological change after being implanted in the arterial system, while venous autografts undergo major changes with an initial scattered loss of endothelium and marked thickening due to a proliferative reaction. The challenge to the cardiac surgeon is to revascularize the entire left ventricle with the IMAs. We have found this possible in most patients with advanced three-vessel disease by using both IMAs either as in situ grafts or free grafts with as many sequential anastomoses as necessary to achieve full revascularization. Our use of the term in situ refers to the grafts origin from the subclavian artery as opposed to a free IMA graft arising from another site.

Transesophageal Echocardiography During Repair of Congenital Cardiac Defects: Identification of Residual Problems Necessitating Reoperation

One advantage of intraoperative transesophageal echocardiographic (TEE) evaluation during surgery for congenital heart disease is detection of suboptimal repairs, thus providing the opportunity to return to cardiopulmonary bypass (CPB) to repair residual defects. The purpose of this study was to evaluate the impact of TEE on decisions to return to CPB. Two-hundred-thirty infants and children with a variety of defects were studied with size-appropriate TEE probes. Patients were grouped by anatomic defect or surgical procedure for which TEE was requested. After CPB, pre- and post-CPB TEE anatomic, functional, and flow evaluations were compared. TEE findings prompted a return to CPB to repair residual defects in 17 of 230 (7.4%) patients. By diagnosis, return to CPB occurred in 9 of 28 (32%) patients with left ventricular outflow tract obstruction, 5 of 78 (6.4%) patients with ventricular septal defect, 1 of 16 (6%) patients with switch-repaired transposition, 1 of 32 (3%) with aortic valve disease, and 1 of 3 with double outlet right ventricle. All post-CPB diagnoses were confirmed during reoperation. Although post-CPB TEE provided reassuring information in patients with other diagnoses, TEE impact on return to CPB appears to be significant in a small group of primary diagnoses. The sensitivity and specificity of TEE determination of the need for reoperation were 89% and 100%, respectively. By identifying the site, severity, and mechanism of residual problems, TEE offers substantial utility in detection of residual problems in need of reoperation.

Axillofemoral bypass: A critical reappraisal of its role in the management of aortoiliac occlusive disease

Two hundred twenty-four consecutive patients (361 graft limbs) who underwent bypass grafting with the USCI Sauvage filamentous velour Dacron arterial prosthesis for aortoiliac occlusive disease over the 9 year period 1970 to 1979 are reviewed. Eighty-four axillofemoral (23 percent of patients), 210 aortofemoral (47 percent of patients), and 67 femorofemoral grafts (30 percent of patients) had cumulative patency rates of 72.1, 91.1, and 86.4 percent, respectively. Experimental and clinical factors influencing the patency of axillofemoral grafts are discussed, and the concept of an improved porous Dacron prosthesis specific for the axillofemoral site is presented.

Deep Hypothermia in Cardiovascular Surgery

Abstract Recent experimental studies and clinical application of deep hypothermia for cardiovascular surgery are reviewed. At most institutions, surface hypothermia alone or in combination with limited cardiopulmonary bypass has been employed. Circulatory dynamics were well maintained following prolonged cardiac arrest at 20°C. Some degree of acidosis usually developed after the arrest period but was gradually corrected during rewarming. Total circulatory occlusion could be maintained for at least one hour at 20°C. without evidence of cerebral damage in infants. Many complex congenital cardiac anomalies, including transposition of the great arteries, total anomalous pulmonary venous return, ventricular septal defect, and tetralogy of Fallot, have been successfully corrected in the first few weeks of life. Less encouraging results have been achieved in patients with infradiaphragmatic total anomalous pulmonary venous return, complete atrioventricular canal, or pulmonary atresia.

An Anatomical Comparison of Human, Pig, Calf, and Sheep Aortic Valves

he limited availability of aortic valves for transplantation has stimulated efforts to establish easily obtainable sources of suitT able valve grafts. T o this end, several groups have investigated the clinical use of heterografts. Some of these heterografts have functioned at least two years [ l , 51. It has been noted, however, that certain animal aortic valves vary in configuration from the human valve. This study is presented in the interest of defining certain aspects of the comparative anatomies of human, pig, calf, and sheep aortic valves so as to facilitate the selection of the most favorable heterograft donor species.

Axillofemoral bypass with externally supported, knitted Dacron grafts: A follow-up through twelve years

PURPOSE The purpose of this study was to review our experience with externally supported, knitted Dacron grafts used for axillofemoral bypass. METHODS Retrospective analysis was performed on records of 79 consecutive axillofemoral bypass graft operations performed on 77 patients from January 1978 to April 1990. RESULTS The mortality rate within 30 days of operation was 5% (four of 79); 36 patients died in the follow-up period; none died of graft causes. During this 12-year period (mean follow-up 42 months) three patients were unavailable for follow-up. The primary patency rate was 78% at 5 years and 73% at 7 years, with no change thereafter. Neither the graft configuration (i.e., axillounifemoral [n = 50] vs axillobifemoral [n = 29]) nor patency of the superficial femoral artery had an impact on the primary patency rate. Patients who underwent surgery for disabling claudication (n = 30 grafts) had a primary patency rate of 80% at 6 years compared with 65% at 6 years for those who required surgery for limb salvage (n = 49 grafts); the difference was not significant (p = 0.37). Actuarial survival of patients with axillofemoral grafts was 23% at 10 years compared with 72% in a concurrent population of patients with aortofemoral bypass (p < 0.001). CONCLUSION These findings indicate that axillofemoral bypass grafts may be appropriate for high-risk patients with severe aortoiliac disease who require revascularization for either limb salvage or incapacitating claudication.

A Five-to Seven-Year Experience with Externally-Supported Dacron Prostheses in Axillofemoral and Femoropopliteal Bypass

We have examined the clinical results of 56 externally-supported (EXS) Dacron grafts in the axillofemoral position and 117 in the femoropopliteal position. Results have been analyzed from two perspectives: primary patency concerns only those grafts that had never occluded; extended patency refers to all open grafts including those whose continued patency is the result of thrombectomy. The 5-to 7-year life-table patency rates are: axillofemoral 8 mm and 6 mm bypass: primary 75% and extended 97%; above-knee femoropopliteal 6 mm bypass: primary 78% and extended 93%; below-knee 6 mm femoropopliteal bypass: primary 41% and extended 91%. In contrast, the results for the 5 mm grafts used for femoropopliteal bypass were inferior to the 6 mm grafts: femoropopliteal 5 mm bypasses had an above-knee primary patency rate of 44% and an extended rate of 55%, with a below-knee primary patency rate of 15% and an extended rate of 32%. Rendering the noncrimped porous Dacron prosthesis kink and compression resistant by an external support coil appears to increase its potential for successful use, especially in 8 mm axillofemoral and 6 mm femoropopliteal bypasses.

Morphological Alterations in Vital Organs After Prolonged Cardiac Arrest at Low Body Temperature

Abstract Surface-induced deep hypothermia was carried out in 34 adult mongrel dogs using ether anesthesia, Rheomacrodex, and respiratory alkalosis. Cardiac arrest was instituted for 30, 60, or 90 minutes at a temperature of 18° to 20°C. All animals were resuscitated, rewarmed, and sacrificed up to two and one-half years postoperatively. One other group was only cooled and rewarmed without cardiac arrest. Myocardial sections showed focal areas of cell necrosis with cytoplasmic band formation, and in the later specimens calcification and interstitial fibrosis had developed. These changes were more severe in the animals subjected to cardiac arrest. The alterations in pulmonary tissue consisted only of patchy atelectasis and alveolar hemorrhage in the early specimens. The kidney and spleen were unaltered. Some liver sections showed widening of centrilobular sinusoids and vacuolization of hepatic cells. All the brains examined had slight anoxic changes; however, it was not possible to differentiate normal from hypothermic brains. There was no correlation between morphological changes and duration of total circulatory arrest.

Femoropopliteal bypass with externally supported knitted Dacron grafts : a follow-up of 200 grafts for one to twelve years

PURPOSE This article reports our experience with externally supported, preclotted knitted Dacron grafts in femoropopliteal bypass. METHODS This is a retrospective analysis of a consecutive series of 154 patients who received 200 grafts (175 above knee and 25 below knee). Follow-up extended to 12 years (mean 59 1/2 months). RESULTS Primary patency rates for the entire series were 75%, 70%, and 47% at 3, 5, and 10 years, respectively. Above-knee grafts had 76%, 71%, and 50% rates and 3, 5, and 10 years, respectively. Below-knee grafts had 65% and 57% at 3 and 5 years, respectively. Limb-salvage rates were 87%, 79%, and 73% at 3, 5, and 10 years, respectively, for the 57 limbs operated on because of critical ischemia. The most significant predictor of graft failure was poor runoff as determined by preoperative arteriography. The effect of poor runoff was most pronounced in the first 3 months. CONCLUSION Externally supported, preclotted knitted Dacron grafts provide encouraging primary patency rates for above-knee femoropopliteal bypass. Poor leg vessel runoff is a major determinant of early graft failure.

Left Ventricular Outflow Tract Obstruction: An Indication for Intraoperative Transesophageal Echocardiography

Transesophageal echocardiography (TEE) provides detailed anatomic imaging of both discrete and complex forms of left ventricular outflow tract (LVOT) obstruction, and Doppler techniques provide additional information regarding the site, mechanism, and severity of the obstruction. Because the transaortic surgical approach to LVOT obstruction often provides limited direct visualization during surgery, we sought to evaluate the utility of intraoperative TEE during surgery for LVOT obstruction. We tested the hypotheses that intraoperative TEE would (1) be useful in defining the level and nature of LVOT obstruction, (2) serve to direct the surgical approach, (3) define the adequacy of relief of LVOT obstruction, and (4) detect surgical complications. Study population consisted of a consecutive series of 27 infants and children undergoing surgery for LVOT obstruction. Patient age ranged from 0.5 to 17.9 years, and weight from 5.4 to 71.2 kg. In 14 patients LVOT obstruction resulted from a discrete membrane, whereas 13 had complex forms of LVOT obstruction. Fully anesthetized and monitored patients were examined with 5 MHz TEE probes appropriate to the size of the patient. In the 14 patients with discrete LVOT obstruction, discrete membranes were identified by TEE in all; gradients ranged from 36 to 75 mm Hg. In 13 of 14 patients, postbypass TEE demonstrated removal of the membrane and excellent relief of gradients. In one of these patients, TEE demonstrated a small ventricular septal defect acquired during resection; the patient was returned to bypass for closure. In one patient, return to bypass for further resection of LVOT obstruction was prompted by TEE demonstration of a high residual gradient. In the 13 patients with complex LVOT obstruction, TEE demonstrated the complexity of LVOT obstruction in all. Gradients ranged from 4 to 95 mm Hg. Although this information was used in surgical planning, five patients had high residual gradients after bypass and underwent further resection. An additional two were returned to bypass for mitral valve replacement. Overall, 8 of 27 patients (29.6%) were returned to bypass based on TEE demonstration of residual anatomic or hemodynamic abnormalities. This occurred significantly more frequently in complex LVOT obstruction than in discrete LVOT obstruction (p = 0.045). We conclude that intraoperative TEE has substantial utility in the demonstration of site, mechanism, and severity of LVOT obstruction and for surgery designed to relieve LVOT obstruction. We believe that TEE should be an integral part of surgical management of LVOT obstruction.