Daniel M. Rose

Prevention of Reperfusion Injury of the Ischemic Spinal Cord: Use of Recombinant Superoxide Dismutase

We investigated the effect of recombinant superoxide dismutase, an oxygen free radical scavenger, on the prevention of reperfusion injury of the ischemic spinal cord. Somatosensory evoked potentials (SEPs) were obtained in 23 dogs. Spinal cord ischemia was produced by cross-clamping the descending thoracic aorta just distal to the origin of the left subclavian artery through a left thoracotomy. Mean proximal aortic blood pressure was maintained between 90 and 100 mm Hg by partial exsanguination. Serial SEPs were obtained at 60-second intervals until the SEP disappeared. Aortic cross-clamping was continued for 10 additional minutes after the disappearance of the SEP. In Group 1 (N = 8), no medication was given when the aortic cross-clamp was removed. In Group 2 (N = 8), a bolus of 25,000 units of superoxide dismutase was injected into the proximal aorta prior to removal of the aortic cross-clamp, and was followed by 5,000 units per minute for 10 minutes after release of the cross-clamp. In Group 3 (N = 7), 50,000 units of superoxide dismutase was administered as a bolus prior to removal of the aortic cross-clamp, followed by an additional 10,000 units per minute for 10 minutes as in Group 2. The postoperative neurological status was assessed by Tarlovs criteria. There was no significant difference in aortic cross-clamp time among the three groups. Paraplegia developed in 4 animals in Group 1; the remaining 4 dogs had paraparesis. In Group 2, paraparesis developed in 2 of 8 dogs; the other 6 had no neurological injury. All the animals in Group 3 had complete recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

Internal Mammary Artery Bypass Grafting: Influence on Recurrent Angina and Survival in 2,100 Patients

Internal mammary artery (IMA) bypass grafting to the anterior descending coronary artery was performed in 2,100 patients between January 1978 and July 1986. The average number of additional saphenous vein grafts (SVGs) per patient was 1.8. During the same period, 1,753 patients underwent coronary artery bypass grafting using an SVG (average number of grafts per patient, 3.2). The average patient age was similar: 62.3 years for IMA grafts and 64.7 years for SVGs. Men constituted two thirds of each group. Left ventricular function was impaired (ejection fraction less than 45%) in 1,071 (51%) of IMA grafts and 847 (48.3%) of SVGs. Other aggregate risk factors, ie, elevated blood pressure, diabetes mellitus, previous myocardial infarction, and congestive heart failure, were similar in each group. Operative results and postoperative mortality of the IMA and SVG patients were comparable. However, the long-term probability of cumulative survival and occlusion-free survival were significantly greater and the probability of recurrent angina and reoperative coronary artery bypass grafting were significantly less in IMA graft patients (p less than 0.015). The relative risk of occlusion in an SVG was 4 to 5 times greater than that of the IMA graft. These data indicate that a patent IMA graft to the anterior descending coronary artery protects against recurrent angina and death from cardiac-related causes, and that the IMA should be the conduit of choice.

Enhancement of CO2 laser microvascular anastomoses by fibrin glue.

Laser-assisted microvascular anastomoses (LAMA) are characterized by low early bursting strength and high aneurysm rates. The effects of fibrin glue on bursting strength (BS), patency, and aneurysm rate of LAMAs were compared to standard suture and laser anastomosis. Rat femoral arteries (0.9-1.1 mm) were anastomosed end-to-end by three methods: (1) conventionally with 8 to 10 interrupted 10-O nylon sutures; (2) 3 stay sutures and CO2 laser (spot size, 0.275 mm; pulse, 0.2 sec, 80 mW); and (3) cryoprecipitated fibrinogen, 35 mg/cc, crystallized thrombin, CaCl, 20 mg/cc, aprotinin (2000 kIU/cc) applied to weld site in conjunction with laser weld as in (2) above. Patency, aneurysms, and histology were evaluated at 3 weeks, and BS (mm Hg) was measured in six additional vessels at 1 and 24 hr. There was no statistically significant difference in patency rates. Both the suture and fibrin glue groups had significantly higher 1 and 24 hr bursting strengths (P less than 0.05) and significantly lower aneurysm rates (P less than 0.001) than standard laser. There was no significant difference in bursting strength between suture and fibrin glue groups. Histology in the fibrin glue group showed medial damage similar to the LAMA and calcification of aneurysmal vessels. Fibrin glue enhancement of LAMAs produces equal patency, higher early bursting strength, and fewer aneurysms at 3 weeks compared to conventional laser.

Analysis of morbidity and mortality in patients 70 years of age and over undergoing isolated coronary artery bypass surgery

With increasing frequency more elderly patients are referred for coronary artery bypass surgery. The operative results of 201 patients 70 years of age and over were compared with the results of 1242 patients under 70 years operated on since 1981. A larger percentage of the elderly patients had triple-vessel disease (66.2% vs 51.0%, p less than 0.001), left main coronary artery obstruction (34.8% vs 16.3%, p less than 0.01), and an ejection fraction of less than or equal to 45% (30.8% vs 21.1%, p less than 0.001). An increase percentage of the patients 70 years of age and over had perioperative myocardial infarction (7.9% vs 4.1%, p less than 0.05), required prolonged ventilatory support (7.9% vs 3.1%, NS), and had major neurologic complications (4.0% vs 1.1%, p less than 0.001). The mortality rate was significantly higher in the elderly patients (5.9% vs 1.9%, p less than 0.01) but did not correlate with degree of coronary artery disease, anginal pattern, or preoperative ventricular function. Only 2 of 12 deaths in the elderly patients were from cardiac causes. This data would suggest that elderly patients have an increased risk for significant cardiac and noncardiac morbidity and mortality following coronary artery bypass surgery and that the higher mortality rate in this age group may be a result of noncardiac organ failure.

Cryopreserved Homologous Saphenous Vein: Early and Late Patency in Coronary Artery Bypass Surgical Procedures

Autologous saphenous vein has proved to be a satisfactory conduit for use in coronary artery bypass grafting. Unfortunately, it is not always available, and substitute material must sometimes be used. When satisfactory autologous veins were not available and the internal mammary arteries were unsuitable, cryopreserved homologous saphenous veins were used in 28 patients. A total of 76 grafts were constructed. Cryopreserved homologous veins were used for 61 grafts, autologous saphenous veins for 11 grafts, and the internal mammary artery for 2 grafts. Coronary angiography was performed 8 to 12 days postoperatively in 16 patients. Of the 31 homografts studied, 8 were occluded (26%), 3 were stenotic (9%), and 20 were normal (65%). The one internal mammary artery and six autologous veins studied were all patent. Six patients underwent late catheterization 6 to 12 months postoperatively. Thirteen homografts were studied at late catheterization: 11 were occluded, 1 was severely stenotic, and 1 was mildly stenotic. At late catheterization, the one internal mammary artery studied was patent, and the one autologous saphenous vein was 95% occluded. Results of both early and late catheterization performed on 18 patients demonstrated that of the 35 homografts studied, 17 (49%) were occluded, 3 (9%) had greater than 70% stenosis, 1 (3%) had mild disease, and 14 (40%) were free of disease. One year follow-up data obtained on 26 patients revealed that 4 patients (15%) died of cardiac causes, 2 patients (8%) died of noncardiac causes, 11 patients (42%) have recurrent angina, and 9 (35%) are asymptomatic. It is concluded that use of cryopreserved homologous saphenous veins for coronary artery bypass grafting should be avoided if at all possible.

In vitro bursting strength studies of laser-welded tissue and comparison with conventional anastomosis

We compared the mechanical integrity of microvascular anastomoses created with a carbon dioxide (CO2) laser with conventional suture anastomoses. Seventy rat femoral artery segments (35 lased and 35 sutured) were harvested at 1, 24, and 72 hours, and 1, 3, 6, and 12 weeks postoperatively. These segments were subjected to increasingly higher in vitro intraluminal hydrostatic pressures (bursting pressure). Conventionally sutured anastomoses exhibited significantly increased ability (p less than 0.05) to withstand greater bursting pressures than the laser-welded tissue up to 3 weeks postoperatively. After the third postoperative week, the laser anastomoses demonstrated increased bursting pressures compared with the conventional anastomoses. At the end of the 12-week period both groups demonstrated an ability to withstand supraphysiologic pressures in excess of 2000 mm Hg.

Surgical therapy of a dissecting aortic aneurysm involving a right sided aortic arch

Dissecting aortic aneurysm involving a right-sided aortic arch is apparently quite rare. A patient with this unusual entity is described. By performing an extraanatomic bypass, the aneurysm was excluded between stainless steel staples. The patient was discharged from the hospital 21 days postoperatively. Although the reasons for the extreme rarity of this entity are not clear, precise anatomic definition is required for successful surgical therapy.