Status of the grafts and the native coronary arteries proximal and distal to coronary anastomotic sites of aortocoronary bypass grafts

Intraoperative blood transfusion is a major risk factor for coronary artery bypass grafting in women

BACKGROUND

Women have been found to have greater mortality from coronary artery bypass grafting than men. Uncertainty exists regarding the causes of the differences in outcomes between men and women after coronary artery bypass grafting.

METHODS

From a database of 2,569 patients having coronary bypass grafting we have determined factors that contribute to poorer outcomes in women compared with men.

RESULTS

Women were found to have greater mortality, postoperative bleeding, and postoperative pulmonary failure than men (p < 0.05). There was no significant difference between men and women in postoperative renal failure, postoperative infection, postoperative stroke, or intraaortic balloon pump (p = not significant). Patient factors other than sex accounted for all the significant predictors (stepwise logistic regression) of mortality, postoperative bleeding, postoperative renal failure, postoperative pulmonary failure, postoperative stroke, need for intraaortic balloon pump, and postoperative infection (p < 0.05). Poorer outcomes in women are associated with greater need for transfusion during operation. Diabetes is predictive of renal failure and stroke.

CONCLUSIONS

Mortality and morbidity is less in men despite their higher preoperative creatinine level, greater incidence of reoperation, lower ejection fraction, and more common atherosclerosis of the ascending aorta.

Fatal haemorrhage following intra-aortic balloon counterpulsation: a case report and a brief review of its clinico-pathological and medico-legal aspects

Intra-aortic balloon counterpulsation may result in serious and possibly fatal vascular complications, such as arterial dissection, in as many as 20 per cent of cases. A significant proportion of these complications may go unrecognized clinically. The following is an account of such a case from Singapore in which an elderly patient with a history of severe ischaemic heart disease died within 25 hours of coronary bypass surgery (resulting from massive intraperitoneal haemorrhage), as a consequence of post-operative intra-aortic balloon counterpulsation. The clinico-pathological and medico-legal aspects of the case are also discussed, together with a brief mention of the role of post-mortem coronary angiography in assessing venous graft patency and integrity.

The endothelium: a key to the future

The vascular endothelium is a complex modulator of a variety of biological systems and may well be the key to definitive success in the treatment of cardiovascular disorders. Surgically-induced endothelial injury may occur preoperatively during cardiac catheterization and intraoperatively from mechanical manipulation, ischemia, hypothermia, and exposure to cardioplegic solutions. The normal endothelium is antithrombogenic and yet promotes platelet aggregation and coagulation if injured. Vasospasm, occlusive intimal hyperplasia, and accelerated arteriosclerosis can also all occur as a result of endothelial injury. Furthermore, endothelial injury is harmful even in the absence of disruption of its monolayer integrity. Thus, preservation of the endothelium should be an additional objective for all cardiovascular surgeons. Synthetic vascular grafts, cardiac valves, and artificial ventricles do not spontaneously endothelialize and thus usually require some form of anticoagulation to maintain patency. Hence, endothelialization of prosthetic implants became an attractive concept. A number of different methods of obtaining an endothelial lining of prosthetic material has since been developed; these include facilitated endothelial cell migration, and endothelial cell seeding by using either venous or microvascular endothelial cells. Manipulating the endothelium might well provide the next major advancement for therapeutic and preventive measures for cardiovascular disease.

Percutaneous transluminal angioplasty in patients with prior myocardial revascularization surgery

Direct myocardial revascularization surgery using either the saphenous vein or internal mammary artery has become the definitive surgical treatment for coronary artery occlusive disease. Certain patients who have undergone these procedures, however, have recurrent myocardial ischemia due to progression of disease in unbypassed vessels, to obstruction in the arteries distal to the insertion of the bypass conduit, or to disease of the conduit itself. Balloon angioplasty may be used to relieve myocardial ischemia in these situations; however, initial studies suggested a low primary success rate coupled with excessive mortality and morbidity. Improvements in patient selection, equipment and technical expertise now allow angioplasty to be performed in this patient population with results comparable to that in the general coronary angioplasty population. Of the 3,016 angioplasty procedures performed between September 1980 and June 1987, 236 patients had previously undergone revascularization surgery. The primary success rate was 93% (390 of 419 stenoses successfully dilated). Overall, clinical restenosis was observed in 39%, including a 43% restenosis rate in patients undergoing only saphenous vein graft angioplasty. This did not differ appreciably from the restenosis rate in postbypass patients undergoing angioplasty of only native vessels (37%) or internal mammary arteries (42%). Emergency revascularization surgery was required in 7 of 236 patients (3%), each of whom had myocardial infarction. One of 236 patients (0.4%) died. Thus, angioplasty may be used to relieve recurrent myocardial ischemia in patients with prior direct myocardial revascularization procedures with a high initial success rate and acceptable risk. Early (less than 6 months) restenosis is not infrequent and remains the largest obstacle to a satisfactory clinical outcome.(ABSTRACT TRUNCATED AT 250 WORDS)

Thrombosed, ruptured atheromatous plaques in saphenous vein coronary artery bypass grafts: ten years' experience

During the past decade the number of patients undergoing saphenous vein coronary artery bypass grafting (CABG) has increased worldwide. With a rate of late graft occlusion approximating 4% each year, the number of patients at risk for late graft occlusion continues to increase. Whereas in 1976 only 0.8% of the CABGs performed at our institution were reoperations for occluded grafts, by 1985 repeat procedures comprised 12.4% of the CABGs performed. Excised, occluded saphenous vein grafts from 52 of 119 (44%) of these patients showed thrombosis superimposed on ruptured atheromatous plaques. Ten autopsy patients showed similar lesions in their occluded grafts. The lesion was present in grafts excised as early as 3 years and as late as 14 years after bypass surgery; most occurred 5 to 10 years after implantation. Neither age at first bypass, sex, nor coronary artery bypassed permitted prediction of the occurrence of the lesion. Thrombosed, ruptured atheromatous plaque is a common, clinically significant mechanism of late graft occlusion. It is associated with recurrent symptoms that necessitate repeat revascularization and may result in death. The lesion may also be amenable to thrombolytic therapy, angioplasty, or both.

State of the vein grafts, native coronary arteries, and myocardium and principal cause of death in patients dying after aortocoronary bypass grafting

Fifty five patients with 108 coronary bypass saphenous vein grafts were studied at necropsy. The mean duration of the grafts was 153 days (SD 516). The luminal narrowing of the native coronary arteries proximal to, at, and distal to the vein graft anastomoses and the narrowing of the non-grafted arteries were evaluated planimetrically. Twenty nine per cent of coronary arteries distal to graft anastomoses showed at least 76% narrowing and 50-75% occlusion was seen in 39% of such arteries. Fifty three per cent of non-grafted arteries showed at least 76% luminal narrowing and 26% had 50-75% narrowing. Six patients (11%) had surgically induced dissection of coronary arteries. Seventy seven vein grafts (71%) showed no appreciable luminal narrowing. Problems related to operative technique caused 30% of the deaths.

Morphologic changes in long-term saphenous vein bypass grafts

A retrospective autopsy study was performed in 56 patients who had undergone saphenous vein bypass graft (SVBG) surgery 12 to 168 months prior to death. Twenty-five grafts had atherosclerosis, 66 grafts had fibrointimal proliferation, and 26 grafts were fibrotic with total occlusion. No significant differences were noted among the three morphologic groups with regard to age of the patient or number of native coronary arteries severely narrowed. Vein grafts with fibrointimal proliferation occurred with greater frequency in patients with systemic hypertension (p less than 0.001), and atherosclerotic grafts were more prevalent in patients with hypercholesterolemia (p less than 0.02). Therefore, the presence of risk factors may determine the type of change that occurs in saphenous vein bypass grafts: systemic hypertension leads to fibrointimal proliferation, whereas hypercholesterolemia leads to atherosclerotic change.

Coronary artery bypass grafting in women. A ten-year perspective

Between January 1974 and December 1983, 3279 patients have undergone isolated coronary artery bypass (CAB) grafting at the Johns Hopkins Hospital. There were 639 women in this group. Women represented 18 to 22% of the patients having isolated CAB grafting throughout the 10-year period, except in 1976 when only 13% of the CAB patients were women. Mean age-at-operation for women has increased from 53.9 to 61.1 years since 1974, and was higher than the mean operative age of men during each of the 10 years. Although the oldest woman undergoing CAB grafting in 1974 was 64 years old, the eldest in 1983 was 84 years old. Except for an older mean age-at-operation for women and a higher incidence of unstable angina prior to surgery, the only other significant difference in the clinical status of female versus male CAB patients, detected by a case control analysis, was the smaller body surface area of women compared to men. Although operative mortality was significantly greater for women during most of this review period, mortality was similar during 1983 (2.6% for men versus 2.4% for women), in spite of a significantly higher incidence of unstable angina in the female group (54% for women versus 35% for men). The improved survival noted following coronary bypass grafting in women, which occurred in spite of the advancing age of the female group, supports an aggressive approach to surgical intervention in women with severe coronary artery disease.

Remnant saphenous veins after aortocoronary bypass grafting: analysis of 3,394 centimeters of unused vein from 402 patients

To assess the status of a saphenous vein (SV) excised for coronary artery bypass grafting (CABG), 3,394 cm of remnant SV from 402 patients who underwent CABG were examined. The SV remnants were 0.5 to 52 cm long (mean 8.4). They were sectioned into 5-mm-long segments, and the resulting 6,788 five-millimeter segments were examined histologically: 5,896 (87%) were narrowed 0 to 25% in cross-sectional area by fibrous tissue; 853 (12%) were narrowed 26 to 50%; 23 (0.6%), 51 to 75%, and 16 (0.4%) segments were narrowed 76 to 100%. Of the 16 segments severely narrowed, 7 (44%) were nearly totally occluded by fibrous tissue. In 17 patients who died within 24 hours of CABG, similar degrees of luminal narrowing were observed in remnant segments and in utilized segments of SV. Thus, significant preexisting luminal narrowing of SV used for CABG is infrequent. The intimal fibrous thickening is variable within the same vein when each 5-mm-long segment is analyzed; it is variable from 1 vein to another in the same patient, and it varies among patients.

Reduction of thrombosis in canine coronary bypass vein grafts with dipyridamole and aspirin

The potential benefit of platelet inhibitor drugs in reducing early thrombosis of coronary arterial vein bypass grafts was assessed in dogs. There were 26 control dogs and 24 dogs treated with dipyridamole, 55 mg/day plus aspirin, 325 mg/day. The dogs in both groups were killed at 2 hours and 1, 2, 3, 7 and 14 days after operation. The grafts were perfused with fixative in vivo, harvested and examined with light microscopy. Severe alterations of the graft wall were observed in the dogs in both groups. The grafts in the control group had a high incidence rate of thrombosis, which occurred early after the operation; those in the treated group had a significantly reduced incidence of thrombosis (p = 0.025). Our study indicates that a combined regimen of dipyridamole and aspirin is effective in reducing early graft thrombosis in dogs.

Percutaneous transluminal dilation of aortocoronary saphenous vein bypass grafts

To evaluate the efficacy of percutaneous transluminal angioplasty as a possible alternative to repeated open heart surgery for symptomatic aortocoronary saphenous vein graft stenoses, the procedure was initiated at Shadyside Hospital in January 1978. Percutaneous transluminal angioplasty has been used in nine aortocoronary graft stenoses and 11 native coronary artery stenoses. Of the nine grafts, eight (88 percent) were successfully dilated, including three that had been totally closed as visualized by angiography. Of the 11 coronary dilations, only four (36 percent) resulted in improved flow. The more favorable results experienced with the graft dilations was thought to be due to the nature of the occlusive processes affecting these grafts. The fibrous intimal proliferative disease that is found in most grafts is easily compressible, while the nature of the disease in the coronary arteries is not so readily predictable. Better instrumentation and careful evaluation before and after angioplasty will improve the results and extend the indications for coronary artery and saphenous vein graft transluminal angioplasty.

Quantitation of coronary arterial narrowing at necropsy in sudden coronary death: analysis of 31 patients and comparison with 25 control subjects

A quantitative analysis of the degree and extent of coronary arterial narrowing by atherosclerotic plaques in the entire lengths of each of the four major coronary arteries in a group of patients dying suddenly from coronary heart disease ("sudden coronary death") is described at necropsy. Cross sections were examined histologically in a total of 1,564 five mm long segments of the left main, left anterior descending left circumflex and right coronary arteries in 31 patients with sudden coronary death, and the observations were compared with those from examination of 1,100 five mm segments of the major epicardial coronary arteries in 25 control subjects. An average of 25 cm (50 five mm segments) of coronary artery were examined from each patient and an average of 22 cm (44 five mm segments) from each control subject. Of the 1,564 five mm segments examined in the 31 study patients, 557 (36 percent) were 76 to 100 percent narrowed in cross-sectional area by atherosclerotic plaques (control subjects 3 percent), 536 (34 percent) were 51 to 75 percent narrowed (control subjects 22 percent), 360 (23 percent) were 26 to 50 percent narrowed (control subjects 42 percent) and only 111 segments (7 percent) had 25 percent or less narrowing (control subjects 33 percent). The amount of severe (greater than 75 percent) narrowing of the right, left anterior descending and left circumflex coronary arteries was similar. Additionally, the amount of severe (greater than 75 percent) narrowing in the distal one half of the right, left anterior descending and left circumflex coronary arteries was similar to that in the proximal halves of these three arteries. The number of 5 mm coronary arterial segments narrowed 76 to 100 percent in cross-sectional area in the 31 study patients was not affected by the patient's age of death, sex, presence or absence of previous angina pectoris or myocardial infarction or the weight of the heart.

Reduction of intimal thickening in canine coronary bypass vein grafts with dipyridamole and aspirin

The potential benefit of platelet inhibitor drugs on coronary arterial bypass vein grafts was assessed in dogs with magnification-corrected angiographic luminal measurements and quantitative histologic evaluation of the vein grafts. There were 11 control animals and 11 animals treated with dipyridamole, 55 mg/day, plus aspirin, 325 mg/day. Eighteen animals with patent grafts were studied when electively killed 2, 4 or 6 months after grafting. At 14 days, there was greater angiographic narrowing in the most distal 1 cm of vein grafts in control than in treated dogs (P less than 0.01). This same angiographic narrowing persisted in control dogs until they were killed (P less than 0.03). Computer-assisted measurements of the entire area of intimal thickening were done on vein graft cross sections taken 1 cm from the distal anastomosis. The circumference of the vein grafts at the intimal-media junction was measured from the same section and the potential maximal luminal area calculated. The calculated luminal narrowing due to intimal thickening was greater in control than in treated dogs (P less than 0.03). These data correlate well with the demonstrated angiographic narrowing. The findings indicate that the degree of early intimal thickening that persists 2 to 6 months postoperatively in canine coronary bypass vein grafts may be reduced by the platelet inhibitor combination of dipyridamole plus aspirin.

Revascularization of the right coronary artery

This study was undertaken to evaluate revascularization of the right coronary artery with regard to factors that enter into the decision to graft less significant lesions, such as graft flow, graft patency and progression of proximal disease. The results of grafting the right coronary artery were studied in 23 patients with lesions reducing luminal diameter by less than 50 percent (Group 1), 35 patients with luminal narrowing of 50 to 70 percent (Group 2) and 112 patients with greater than 70 percent luminal narrowing (Group 3). At operation there was no significant difference in saphenous vein graft flows among the three groups. Postoperatively the mean follow-up period was 20, 27 and 26 months, respectively. Graft patency was not significantly different among the three groups. Progression of the proximal lesion was studied and compared with that in 71 ungrafted right coronary arteries, 60 with less than 50 percent stenosis and 11 with more than 50 percent stenosis. Among vessels with less than 50 percent narrowing, the proximal lesion showed progression in 26 percent of the ungrafted vessels and in 83 percent of the grafted vessels (P less than 0.005); progression to total occlusion occurred in 3 percent of the former and in 28 percent of the latter (P less than 0.005). Progression to total occlusion was more frequently associated with a patent than with an occluded graft (P less than 0.05). The occurrence of significant progression in ungrafted vessels and the lack of effect on graft patency of the severity of the proximal disease suggest that revascularization of less significant lesions may be of value. However, the resultant increase in progression of proximal disease makes the patient dependent on the long-term patency of the vein graft.

Long-term anatomic fate of coronary-artery bypass grafts and functional status of patients five years after operation

To assess long-term results, coronary and graft angiography was performed 53 to 84 months after operation in 22 of 30 consecutive patients who had undergone coronary-artery bypass grafting before 1973, and who had at least one graft patent at an early (three to nine months) postoperative study. Of the 33 grafts, 31 were patent at late study. All patients had severe symptoms before operation. Of 16 who became asymptomatic early after operation, angina pectoris later redeveloped in 11. Progression of disease in ungrafted vessels accounted for symptomatic deterioration in nine of these 11 patients. We conclude that most grafts patent several months after operation remain so for at least 4 1/2 years, and that although most patients improve symptomatically after operation, symptomatic deterioration is common in the succeeding years and is most often due to progression of disease in ungrafted vessels.

Myocardial revascularization in women

During the period January, 1970, through June, 1977, 1,541 patients underwent coronary artery bypass grafting; 241 of them were women (15.6%). Operative mortality rates for the entire study were 2.4% in men and 3.7% in women, but they showed a marked decline in women during 1975 to mid-1977, with only 2 deaths in 140 patients (1.4%). Women comprised a larger percentage of patients (16.7%) in these later years. Women were slightly older, received fewer grafts, had better preservation of ventricular function on preoperative studies, and had more severe anginal symptoms than men. Patency rates were significantly lower in women at 1 month, 1 year, and 3 years. Five-year survival was not significantly different between women (88.3%) and men (93.5%). Many of these findings may be explained on the basis of women having smaller coronary arteries than men. These favorable results differ from earlier reports of higher mortality rates in women and indicate that myocardial revascularization should not be withheld from female patients.

Changes in saphenous veins used as aortocoronary bypass grafts

This report describes morphologic changes in saphenous veins used as aortocoronary bypass conduits, and discusses the relative contribution of various factors to these changes. The three primary changes are: (1) medial fibrous replacement, (2) adventitial fibrous proliferation, and (3) intimal fibrous proliferation. Medial fibrous replacement is caused by vein wall ischemia with loss of smooth muscle cells; adventitial fibrous proliferation is the result of organization of fibrin deposits and repair of ischemic injury; and intimal fibrous proliferation results from some stimulus, probably fibrin deposition on injured intima, which causes stimulation of smooth muscle cells to become fibroblasts or "myointimal cells". Although all grafts show some changes, the degree and severity of these three changes is variable along the length of the grafts and among separate grafts in the same patient.