Atherosclerotic changes in coronary vein grafts six years after operation

Aortic distensibility and coronary artery bypass graft patency

Background

Aortic distensibility is an elasticity index of the aorta, and reflects aortic stiffness. Coronary artery disease has been found to be substantially associated with increased aortic stiffness. In this study we aimed to retrospectively analyze the association of angiographically determined aortic distensibility with the patency rates of coronary bypass grafts

Methods

The study was conducted in the Cardiology department of the Applied Research Centre for Health of Uludağ University. The coronary angiograms of 53 consecutive coronary bypass patients were analysed retrospectively. Aortic distensibility was calculated using the formula: 2 × (change in aortic diameter)/(diastolic aortic diameter) × (change in aortic pressure). The number of stenosed and patent bypass grafts and the patient characteristics like age, risk factors were noted.

Results

There were 44 male (83%) and 9 female (17%) cases. Eighteen cases had only one saphenous vein grafting. The number of cases with two, three and four saphenous grafting were 18, 11 and 1; respectively. In the control angiograms the number of cases with one, two, three and four saphenous vein graft obstruction were 15 (31.3%), 7 (14.6%), 1 (2.1%) and 1 (2.1%) respectively. The aortic distensibility did not differ in cases with and without saphenous graft occlusion (p > 0.05). Also left internal mammary artery (LIMA) graft patency was not related to the distensibility of the aorta (p > 0.05). We also evaluated the data for cut-off values of 50 and 70 mmHg of pulse pressure and did not see any significant difference between the groups in terms of saphenous or LIMA grafts.

Conclusion

In this study we failed to show association of angiographically determined aortic distensibility with coronary bypass graft patency in consecutive 53 patients with coronary artery bypass graft surgery (CABG).

The Internal Mammary Artery and Vein as Recipient Vessels for Microvascular Breast Reconstruction:

Clinical applications for the internal mammary artery include use as an arterial conduit for coronary revascularization and as a recipient artery for microvascular reconstruction of the breast. This study was completed in an attempt to resolve the controversy over which indication should have priority. Five hundred twenty women with breast cancer who underwent breast reconstruction were reviewed. Of these, 240 were 50 years of age or more and were evaluated for cardiac disease. Three components were studied that included analysis of factors related to cardiac function (prior cardiac surgery, specific cardiac disorders, and cardiac medications), analysis of risk factors related to cardiac disease (hypertension, diabetes mellitus, and tobacco use), and analysis of factors related to the reconstruction (selection of recipient vessels, type of reconstruction). The women were stratified based on age-50 to 59 years, 60 to 69 years, and older than 70 years-to analyze trends based on advancing age. Results demonstrated that the incidence of coronary artery disease was 2 in 240 women (0.8%) and that the incidence of factors related to cardiac function and the incidence of risk factors related to cardiac disease appear to increase with advancing age. The internal mammary vessels were used in 35 of 114 free tissue transfers with no adverse sequelae. No woman in whom the internal mammary artery was used has developed coronary artery disease. The 2 women with coronary artery disease were reconstructed with implants. Based on the results of this study, the author thinks that use of the internal mammary artery as a recipient vessel for microvascular reconstruction of the breast is justified. Options for future coronary revascularization would include the opposite internal mammary artery when available, a saphenous vein graft, or angioplasty.

Adenovirus Mediated Endothelial Nitric Oxide Synthase Gene Transfer Prevents Restenosis of Vein Grafts

The possibility of endothelial nitric oxide synthase (eNOS) gene transfer, which prevents restenosis of vein grafts, was explored in 16 goats. The recombinant adenoviral vector coding endothelial nitric oxide synthase (AdCMVeNOS) and adenoviral vector (AdCMV) were constructed. A total of 6 cm jugular vein was removed, cut into two equal lengths for vein grafts, and infected with AdCMVeNOS or AdCMV in vitro. One segment (2 cm) of each carotid artery was removed. The vein graft that had been infected with AdCMVeNOS was anastomosed to the right carotid artery, and the vein graft that had been infected with AdCMV was anastomosed to the left. The functional expression of eNOS in vein grafts was assessed by the immunohistochemical staining and measurement of NO concentration. The inhibition of intimal hyperplasia in vein grafts was evaluated by the assay of 3H-TDR incorporation, histologic analysis, measurement of intimal thickness, and percent area stenosis. Adenovirus mediated eNOS gene transfer to goat vein grafts resulted in functional transgene expression with increased NO release. Increased local NO production could inhibit intimal hyperplasia and increase the patent rate of vein grafts.

Early quantitative coronary angiography of saphenous vein grafts for coronary artery bypass grafting harvested by means of open versus endoscopic saphenectomy: a prospective randomized trial

OBJECTIVE

Endoscopic saphenectomy is associated with a decreased incidence of wound complications without an increase in histologic trauma or endothelial dysfunction in published reports. Concern remains about the patency of saphenous vein grafts harvested endoscopically and the development of early intimal hyperplasia. The purpose of this study was to compare early quantitative coronary analysis of saphenous vein grafts used for coronary artery bypass grafting harvested with the open versus endoscopic techniques.

METHODS

Forty patients undergoing primary coronary artery bypass grafting surgery with at least 1 saphenous vein graft were randomized preoperatively to open versus endoscopic saphenectomy with bipolar cauterization of side branches. Quantitative coronary angiography was performed a mean of 3 months (range, 1-9 months) after the operation.

RESULTS

There was no statistically significant difference in the patency rates of internal thoracic artery grafts between the open and endoscopic groups and no statistically significant difference in the patency rates of saphenous vein grafts between both groups (85.2% vs 84.4%, P =.991). Quantitative coronary angiography showed no difference in graft stenosis (>or=50% of the internal diameter of the graft) in the body of the saphenous vein grafts in the open versus endoscopic saphenectomy groups (3.7% vs 0%, P =.280).

CONCLUSION

Angiographic appearance and patency rates of saphenous vein grafts harvested with the endoscopic technique are similar to those of saphenous vein grafts harvested with the open technique. These results support the use of endoscopic saphenectomy because of the known lower incidence of wound and infectious complications and superior functional results.

Functional assessment of disease-free saphenous vein grafts at redo coronary artery bypass grafting

BACKGROUND

Reoperations for coronary artery bypass grafting are on the rise. The general rule of replacing all saphenous vein grafts (SVGs) older than 5 years of age at the time of reoperation has recently been challenged on clinical grounds. This study provides functional data of endothelial behavior in long-term vein grafts.

METHODS

Previously placed SVGs were removed at the time of redo operations. Nitric oxide (NO) measurements in real time were carried out before and after stimulation with morphine. The measurements were compared to the angiographic appearance of the grafts obtained prior to operation. Grafts were categorized into 3 groups: disease-free, moderately diseased, and severely diseased.

RESULTS

Sixteen grafts were analyzed. Five were angiographically disease-free, 4 had moderate, and 7 severe disease. In the disease-free group, peak NO production after 10(-6) mol/L morphine stimulation was 35 mol/L, equivalent to the production of native saphenous vein. The severely diseased group did not demonstrate an increase in NO production, and the moderately diseased group produced a small rise in production.

CONCLUSIONS

Measurement of NO release of old SVGs, when angiographically pristine, equals that of native saphenous vein. These findings support the recent clinical observations that long-term angiographically disease-free vein grafts are biologically privileged.

Percutaneous revascularization of lesions with saphenous vein graft failure: influence of chronic total occlusion on early outcome

The purpose of this study was to evaluate a therapeutic strategy of percutaneous transluminal coronary angioplasty (PTCA) in patients with recurrent angina following coronary artery bypass grafting. The study looked at 112 branches associated with graft failure, excluding new lesions in the native coronary artery (NCA). Chronic total occlusion (CTO) was observed in 50% of NCA (56/112) and in 68% of the grafts (76/112). Thirty-three branches (29%) showed CTO in both NCA and the graft. The overall success rate was 86% (96/112). The success rate on NCA was 98% (44/45) in non-CTO, while in CTO it was significantly lower at 62% (18/29). As to grafts, the success rate was 94% (32/34) in non-CTO, while it was 50% (2/4) in CTO. These characteristics, with respect to lesion morphology and the prevalence of CTO, exerted an influence on the selection of the access vessels for revascularization. Early outcome depended on the result of treatment of CTO.

Should angiographically disease-free saphenous vein grafts be replaced at the time of redo coronary artery bypass grafting?

BACKGROUND

Controversy exists regarding the management of angiographically disease-free saphenous vein grafts at the time of redo coronary artery bypass grafting (CABG). Some authorities favor replacement of these disease-free grafts, arguing that occlusion is likely in the near future. Others believe that these grafts are "biologically privileged" and should not be replaced.

METHODS

One hundred thirty-two consecutive patients (113 men, 19 women, aged 46 to 88 years, mean 67 years) underwent redo revascularization with one or more angiographically disease-free saphenous vein grafts at the time of redo CABG. Thirty-six patients had the disease-free grafts replaced (R) and 96 did not (NR). The mean interval from the first CABG was 9.25 years.

RESULTS

Surgical mortality was comparable in the NR and R groups (5 of 96 or 5.2% versus 3 of 36 or 8.3%, respectively; p < 0.5). Survival at 1 and 3 years was higher in the NR group than the R group (98% versus 80%, and 95% vs. 66% respectively; p < 0.0001). Late myocardial infarction was less common in the NR group than in the R group (12 of 91 or 12.9% versus 12 of 33 or 36.4%; p < 0.003). Recurrent angina was less common in the NR than in the R group (21 of 91 or 23.1% versus 15 of 33 or 45.5%; p < 0.015). Cardiac hospitalization was required less commonly in the NR than in the R group (11 of 91 or 12.1% versus 12 of 33 or 36.4%; p < 0.002). In nondiseased grafts undergoing angiographic evaluation late after redo CABG, rate of new stenosis was lower in NR grafts than in R grafts (2 of 12 or 16.7% versus 2 of 3 or 66.7%; p < 0.05).

CONCLUSIONS

With a conservative approach that does not replace nondiseased saphenous vein grafts at redo CABG (1) there is no increase in operative mortality, (2) good late survival is obtained, (3) clinical ischemia related to the NR saphenous vein grafts is uncommon, and (4) NR grafts continue to be patent. We conclude that disease-free vein grafts may not require routine replacement at redo CABG. A randomized study is required for definitive resolution.

Coronary bypass graft fate and patient outcome: angiographic follow-up of 5,065 grafts related to survival and reoperation in 1,388 patients during 25 years

OBJECTIVES

We sought to examine, angiographically, the longterm fate of a large number of mainly venous coronary bypass grafts and to correlate graft patency and disease with patient survival and reoperation.

BACKGROUND

Much is known about bypass graft patency and disease, but the precise relation between graft fate and patient outcome has not been substantiated and documented.

METHODS

A total of 1,388 patients underwent a first coronary artery bypass graft procedure at a mean age of 48.9 years, 234 had a second bypass procedure at a mean age of 53.3 years, and 15 had a third bypass procedure at a mean age of 58.2 years during the 25-year period from 1969 to 1994. Most were male military personnel or veterans; 12% were < or = 39 years old. Of 5,284 grafts placed, 91% were venous and 9% arterial. Angiograms were performed on 5,065 (98% of surviving) grafts early, on 3,993 grafts at 1 year and on 1,978 grafts at 5 years after operation; other examinations were also performed up to 22.5 years after operation, and 353 grafts were examined after > or = 15 years. Grafts were graded for patency and disease. The status of all patients was known at the study's end.

RESULTS

The perioperative mortality rate was 1.4% for an isolated first coronary bypass procedure, 6.6% for reoperation. Vein graft patency was 88% early, 81% at 1 year, 75% at 5 years and 50% at > or = 15 years; when suboptimal grafts, graded B, were excluded from calculation, the proportion of excellent grafts, graded A, decreased to 40% after > or = 12.5 years. After the early study, the vein graft occlusion rate was 2.1%/year. Internal mammary artery graft patency was significantly better but decreased with time. Vein graft disease appeared by 1 year and the rate accelerated by > or = 2.5 years, involving 48% of grafts at 5 years and 81% at > or = 15 years; 44% of the latter grafts were narrowed > 50%. Survival of all patients was 93.6% at 5 years. 81.1% at 10 years, 62.1% at 15 years, 46.7% (150 patients) at 20 years and 38.4% (25 patients) at 23 years after operation. Survival decreased as age increased, but curves approximated "normal" life expectancy for older patients. Survival curves at all ages showed a steeper decline after 7 years. The rate of reoperation increased between 5 years and 10 to 14 years, then decreased to stable levels. Coronary atheroembolism from vein grafts was the major cause of morbidity and mortality associated with reoperation. Vein graft patency and disease were temporally and closely related to reoperation and survival.

CONCLUSIONS

Coronary bypass graft disease and occlusion are common after coronary artery bypass grafting and increase with time. They are major determinants of clinical prognosis, specifically measured by reoperation rate and survival. Intraoperative graft atheroembolism was a major reoperation hazard. Reoperation is definitely worthwhile but entails identifiable risks that must be dealt with.

Intravascular imaging of serial changes of disease in saphenous vein grafts after coronary artery bypass grafting

To clarify the structural changes of saphenous vein grafts after coronary artery bypass grafting, intravascular ultrasound and angioscopic images were obtained from 23 grafts in vivo and 5 grafts and 3 new veins in vitro; the images were compared with histologic findings. Intravascular ultrasound demonstrated a single-layered appearance at new veins and all of the angiographically normal grafts within 6 months after surgery. A triple-layered appearance that might be related to the remarkably proliferative and degenerated intima was revealed histologically at 73.3% of the normal sites of grafts between 5 and 10 years after operation. In 83.3% of the stenoses at several years after operation, angioscopy showed yellow atheromatous plaques, often with a friable surface; a heterogeneous, lucent echo pattern was revealed on intravascular ultrasound. Thus intravascular ultrasound and angioscopy may be used to identify the morphologic changes of graft at different points after implantation more precisely than conventional angiography.

Multiple reoperative coronary artery bypass grafting

Initial reoperative coronary artery bypass grafting is being performed commonly, and an increasing number of patients are being referred for subsequent reoperative coronary artery bypass grafting. From January 1980 through June 1990, 53 patients (52 male, 1 female) underwent a third or fourth coronary artery bypass operation and were retrospectively reviewed. This represented 0.3% (53/17,102) of the coronary artery bypass procedures done during that time period. The mean age was 59 +/- 8 years. The number of grafts placed ranged from one to four with an average of 2.6 per patient. Internal mammary artery grafts were used in 30 patients (57%). The mean left ventricular ejection fraction was 0.52 +/- 0.13. Intraaortic balloon pump support was necessary in 10 patients postoperatively. There were no intraoperative deaths, although 4 patients died in the postoperative hospitalization period. Perioperative myocardial infarctions were diagnosed in 6 patients, 13 patients had perioperative dysrhythmias, and 2 patients sustained a stroke. Superficial wound infections occurred in 5 patients. Late follow-up in 49 patients revealed that 2 other patients have since died, and no further myocardial infarctions have been reported in the survivors. Postoperative 3-year survival is 85%, whereas 3-year myocardial infarction-free survival is 70%. Although there is increased risk of operative complications and early death after multiple reoperative coronary artery bypass grafting, both in-hospital and long-term results suggest that it is an appropriate therapeutic strategy.

Mycotic aneurysms of the carotid arteries--case report and review of the literature

Mycotic aneurysms of the extracranial carotid arteries are rare. We report a new case with a mycotic aneurysm of the carotid bifurcation associated with acute bacterial endocarditis of the aortic valve. A concomitant treatment of both lesions was performed. Twenty-six cases of mycotic aneurysms of the extracranial carotid arteries have been reported in the literature. We present a review of all these cases.

Coronary bypass graft fate: long-term angiographic study

In 222 patients, 741 venous coronary bypass grafts were studied angiographically early, at 1 year and at a late examination at greater than 6.5 years (mean 9.6) after operation; 565 of these grafts were also examined 5 years postoperatively. Grafts were graded for patency and disease considered to be atherosclerotic and for both extent and profile of lesions. Graft occlusion rates increased steadily from 8% early to 20% at 5, 41% at 10 and 45% at greater than 11.5 years after operation. All grafts were considered free of atherosclerosis early, but disease appeared in 8% at 1 year, increasing to 38% at 5 and 75% at 10 years postoperatively. Increasing involvement of vessel wall area was associated with greater protrusion of lesions into the graft lumen. Diseased grafts became more so at subsequent examinations, with occlusion occurring in many. However, absence of disease had little prognostic significance because diseased and abruptly occluded grafts were generated in those with healthy appearance at earlier examinations. For instance, 82% of very diseased grafts at the 5 year study originated from normal grafts at 1 year and 73% of occluded grafts at 1 year had appeared normal early postoperatively. Of 590 patent grafts free of disease at 1 year, 30% were occluded at the late examination, 76% of those patent were diseased, 55% of these were diffusely diseased and 35% were greater than 50% narrowed. Only 17% of the original 590 patent grafts were healthy at this time. Bypass graft atherosclerosis severely limits the long-term utility of these grafts. It is suggested that the solution may lie in some powerful drug regimen.

Progression of native coronary artery disease at 10 years: insights from a randomized study of medical versus surgical therapy for angina

Repeat coronary angiography was performed in 42 patients 10 years after randomization to medical (n = 21) or surgical (n = 21) therapy for chronic angina. The native coronary arteries were classified into 15 angiographic segments and 3 arterial trunks for analysis of progression of coronary artery disease. The incidence rate of disease progression in coronary segments was 24% and 28% in medically and surgically treated patients, respectively (p = NS). Grafted segments showed a 38% rate of disease progression, which was higher than the 18% rate of for nongrafted segments (p less than 0.001) and the overall rate of 24% for medically treated patients (p less than 0.01). Similarly, 29 (94%) of 31 grafted arteries exhibited disease progression compared with 19 (59%) of 32 nongrafted arteries (p less than 0.01) and 42 (67%) of 63 arteries in medically treated patients (p less than 0.01). In grafted vessels, disease progression occurred more often in arteries proximal (84%) to the anastomosis than in arteries distal (16%) to graft insertion (p less than 0.001). Progression occurred in 46% of proximal segments compared with 23% of distal segments (p less than 0.02). Progression was seen in 23 (55%) of 43 segments with an occluded graft compared with 30 (31%) of 96 segments with a patent graft (p less than 0.02). Ten years after randomization, medically and surgically treated patients showed a comparable rate of disease progression in coronary segments. However, surgical therapy appeared to significantly accelerate atherosclerotic progression in the grafted vessels, especially in the proximal portions. Occluded grafts also correlated with an adverse effect on disease progression.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary angioplasty in symptomatic patients after bypass surgery

With the availability of percutaneous transluminal coronary angioplasty (PTCA), the management of patients who present with recurrent angina following coronary artery bypass surgery (CABG) has changed. From January 1987 to December 1988, 149 symptomatic post CABG patients underwent coronary angiography at our institution. Ninety were treated with medical antianginal therapy, 14 had repeat surgery, and 45 underwent PTCA. Complications of repeat CABG included one death, two perioperative myocardial infarctions, and four patients with postoperative supraventricular arrhythmia. PTCA was performed on 42 lesions in 37 native vessels (88% success rate), and on 24 lesions in 23 vein grafts (91.7% success rate). Complications included acute reocclusion (one patient), peripheral artery occlusion (one patient), hematoma formation (one patient), and periprocedure myocardial infarction (one patient). No deaths occurred. At a mean follow-up of 5.9 +/- 3.8 months, 10 patients had recurrent symptoms, six of whom were found to have restenosis. Repeat PTCA was successfully accomplished in four patients; the other two were treated medically. It is concluded that PTCA is a feasible alternative to repeat CABG in selected patients and can be achieved with a high success rate and minimal complications.

Evaluation of arterialized vein graft permeability with Evans blue dye and iodine 125-labeled albumin

This study measured endothelial permeability, quantitatively (with iodine 125-labeled albumin) and qualitatively (with Evans blue dye) in arterialized vein grafts in 9 adult dogs. In each dog, the right common carotid artery was ligated and arterial flow was reconstituted with a 5-cm bypass graft of right external jugular vein. Twenty-four hours before the dogs were killed, each dog received both 125I-labeled albumin (8 microCi/kg) and Evans blue dye (15 mg/kg) intravenously. After the dogs' death, each arterialized vein graft and each left external jugular vein (as control) was harvested and studied. Arterialized vein graft permeability was significantly increased over control at 1, 3, and 6 months (3 dogs at each interval). Scanning electron microscopy revealed confluent endothelium in all specimens. This increased permeability may play a role in vein graft atherosclerosis.

Histopathological study of aorto-coronary bypass grafts with special reference to fibrin deposits on grafted saphenous veins

A histopathological study was performed on 36 patients (60 grafts) who had undergone aorto-coronary bypass graft (ACBG) surgery 0 to 99 months prior to death. The following pathologic changes were found: 1) The thickness of diffuse intimal proliferation in the ACBG progressed with time from graft surgery to death. 2) The media became atrophic and the adventitia was increased slightly in thickness. 3) Fibrin deposits were found in 20 patients on/in the intimal thickenings of the vein graft walls and 7 patients showed incorporated fibrin in the thickened intima even one month after surgery. 4) Atherosclerosis, identified as intimal foam cell accumulation or frank plaques, was seen in only 3 patients 4 years after surgery. Fibrointimal proliferation occurred with relatively greater frequency in patients with fibrin deposits (P less than 0.001). Although it is well known that mural thrombi in vein grafts manifest fibrointimal proliferation, our results suggest that fibrin deposits might be responsible for intimal thickening even one month after graft surgery.

Coronary risk factors six to 12 months after coronary artery bypass graft surgery

Hyperlipidaemia appears to be a major factor in the development of graft atherosclerosis in the five- to 10-year period after coronary artery bypass graft surgery. A preliminary survey of coronary risk factors was conducted in 103 consecutive patients, who lived in the Sydney metropolitan area and who had undergone coronary artery bypass graft surgery six to 12 months previously in a single hospital unit. The information was collected by reply-paid questionnaire (response rate, 93%) and by clinical assessment (measurement rate, 85%). The group was predominantly (86%) male and elderly (mean age, 62 years; 60% of men and 85% of women were aged over 59 years). Seven per cent of the group had undergone a second operation. Approximately two of every three subjects manifested hypercholesterolaemia, one in four subjects manifested hypertension and one in three subjects was overweight, but only one in 20 subjects currently smoked cigarettes. The findings were compared with those in a general population sample; the assumption was made that coronary risk factors would be overrepresented in a sample of patients in whom coronary artery bypass graft surgery had been required. The data suggested that cigarette smoking was receiving appropriate intervention (before or after surgery), that hypertension was receiving some intervention, and that hyperlipidaemia was receiving insufficient intervention. On a purely empirical basis, the appropriate use of a cardiac rehabilitation service is suggested as one possible way of preventing the return of a large number of patients with graft atherosclerosis in later years.

The healing characteristics of autogenous saphenous vein used in the reconstruction of previously implanted arterial saphenous vein grafts

Aortocoronary saphenous vein grafts with early isolated stenoses pose the technical problem of how to deal with these grafts at reoperation. The advisability of using a portion of old graft when reconstructing these grafts was examined. An experimental model was devised in which the anatomical and pathological interfaces between fresh vein and previously inserted vein were studied. Superficial femoral artery from the thigh of 15 dogs was replaced by reversed autogenous saphenous vein. Four months later, the animals were divided into two groups. Group 1 consisted of 8 animals that underwent transection and reimplantation of the middle 4 cm of the vein graft in exactly the same position in which it had been. In Group 2, the 7 animals had the middle 4 cm of the graft replaced with newly harvested reversed saphenous vein. Six months after initial vein graft implantation, the animals were studied. No critical stenoses were seen in the grafts. Pathological study of Group 1 grafts revealed fibrous graft disease of uniform severity throughout the graft, thereby demonstrating that new anastomoses in an old graft do not affect graft disease. Group 2 grafts revealed that the severity of disease in the new interposed segment of the vein graft was less than in the old retained portions of the graft. No untoward reaction causing acceleration of graft disease occurred between old and new vein. Operations using undiseased portions of old vein grafts should be considered a viable option in repeat coronary revascularization for early stenoses.

Saphenous vein coronary bypass graft revisited

To establish a benchmark for the clinical efficacy of PTCA and the IMA graft in our institution, the data from 79 patients who underwent isolated SVBG to the LAD between July, 1971, and December, 1984, were analyzed. Follow-up averaged 96.16 months/patient. Actuarial freedom from reoperation was 100% at 12 months, 95% at 60 months, and 89.4% at 120 months. Actuarial freedom from cardiac death was 100% at 12 months, 94% at 60 months, and 87% at 120 months. Actuarial freedom from an LAD graft failure myocardial event was 100% at 12 month, 94% at 60 months, and 77% at 120 months. Our SVBG failure rate did increase from 1.2%/year during the first 5 years to 3.4%/year during the second 5 years. We are presently selectively employing IMA grafts to the LAD. Our results with the SVBG and the palliative nature of all coronary artery bypass graft procedures remove the imperative to always use the IMA. Individual patient considerations such as age, clinical stability, IMA flow, and the residual anatomy for the potential reoperation are important considerations.

Venous response to endothelial denudation

This paper examines the responses of various rat and rabbit veins to endothelial injury and compares them with endothelial injury in the carotid artery of the same species. Areas of endothelial injury of different sizes were produced by air-drying, enzymatic digestion with trypsin, or rubbing the endothelial surface with a nylon filament attached to the end of a catheter. Two weeks after an extensive area of endothelium had been denuded the artery contained a fibromuscular intimal thickening covered by regenerated endothelium. Experimental endothelial denudation of a similar size and produced by the same methods in a vein elicited a comparable intimal thickening, although more limited, than that in the carotid artery. When the size of the denuded area was large, extensive platelet microthrombi were formed that often caused total thrombotic occlusion in the vein. However, if the denuded area was small, the endothelium regenerated rapidly and no intimal thickening occurred.

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.

Improved graft patency in patients treated with platelet-inhibiting therapy after coronary bypass surgery

One hundred forty-seven consecutive coronary bypass patients were enrolled in a randomized, double-blind, risk-stratified, placebo-controlled prospective trial evaluating the effect on graft patency of 325 mg tid aspirin (ASA) plus 75 mg tid dipyridamole (DP) or ASA alone. One hundred twenty-seven patients (399 total grafts) underwent surgery, initiation of drug therapy 67 +/- 27 (SD) hr postoperatively, five clinic visits, and repeat angiography at 1 year. A logistic regression statistical model was used to determine the effects of 28 different measured variables on graft patency and to adjust for these effects in determining the relationship between antiplatelet therapy and graft occlusion. No patient-specific variable contributed significantly to the prediction of occlusion in either the placebo or the treated group. Six graft-specific variables (arterial diameter, severity of stenosis, graft flow, reactive hyperemia, presence or absence of collaterals, and graft type) did contribute and were included in the model. Twenty-one percent of placebo-treated grafts became occluded. Compared with placebo, the relative risk of graft occlusion with ASA was 0.47 (p = .04); with ASA + DP, it was 0.50 (p = .04). This benefit was principally due to reduction of occlusion in the most common and presumably most important groups of grafts, those in which flow exceeded 40 ml/min, or supplying arteries having luminal diameters greater than 1.5 mm. Grafts lacking reactive hyperemia had a 32% occlusion frequency in placebo-treated patients; relative risk of their occlusion averaged 0.26 (p less than .01) with platelet-inhibiting therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Internal mammary retractor

A new retractor for dissection of internal mammary arteries is described. We have found that the instrument can easily be applied to the chest wall and gives excellent exposure for dissection of the graft from origin to bifurcation.

Adaptation of canine saphenous veins to grafting. Correlation of contractility and contractile protein content

Saphenous veins are used extensively to replace stenotic coronary arteries. However, the contractile and biochemical adaptations of grafted veins are unknown. The three purposes of this work were to characterize the contractile properties of grafted veins, to determine whether altered contractile characteristics were associated with quantitative changes in actin, myosin and collagen, and to determine which changes were associated with the surgical procedure and which with placement in the arterial circulation. Canine saphenous veins were removed and returned to their original location (venous autograft), while others were used to replace a segment of femoral artery (arterial graft). The grafts were removed 1, 4, and 8 weeks later and compared with the contralateral saphenous vein. Both graft types exhibited an increase in sensitivity to norepinephrine but not to potassium chloride. The venous autograft exhibited a reversible reduction in myosin content and in maximum contractile response (force/cross-sectional area) to potassium chloride and norepinephrine. In contrast, the arterial graft exhibited increased wall thickness and content of all measured proteins and decreased maximum contractile response. The latter occurred even though there was an increase in the net production of actin and myosin. Expressing the maximum contractile response in terms of the myosin content did not normalize the contractile response. These results suggest that, except for the elevated sensitivity to norepinephrine, the vein is capable of recovering from the effects of surgery within 8 weeks; however, placement of the vein in the arterial circulation delays this recovery and initiates a hypertrophic response that includes an attenuation of contractile function.

Trends in selection and results of coronary artery reoperations

The first 1,000 patients undergoing isolated coronary artery reoperation were divided into four cohorts of 250 patients each: 1969 to 1976; 1976 to 1979; 1979 to 1981; and 1981 into 1982. Graft failure as an indication for reoperation rose from 26% in Group 1 to 40% in Group 4, and the interval lengthened from 17 to 61 months, presumably a result of late closures 5 to 10 years postoperatively. Progressive atherosclerosis in previously ungrafted vessels has decreased from 62% in Group 1 to 23% in Group 4, a decline attributed to more complete revascularization initially. The frequency of three-vessel disease, stenosis of the left main coronary artery, and left ventricular impairment continues to rise in candidates for reoperation. Yet, operative mortality has declined from 5% to 2%, and most other forms of perioperative morbidity have decreased significantly when the early years are compared with the later experience. The number of grafts per patient has increased from 1.4 to 2.3, and complete revascularization in reoperations has increased from 65% to 76%. After a mean of 29 months, graft patency was 81% overall in 154 patients restudied after reoperation. Patency was similar for grafts to arteries previously involved with graft failure and to arteries not previously grafted. Five-year actuarial survival for patients in the first three cohorts (mean, 57 months) was 89%.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac rehabilitation following coronary artery bypass surgery

Early expectations of coronary revascularization prolonging life and reducing coronary events have been modified by 15 years' experience to mostly initial palliation of ischemic symptoms. Bypass surgery represents only a single therapeutic aspect for coronary atherosclerosis. Technically successful operations often fail miserably without overall risk factor alteration and functional capacity optimization which progressive exercise initiates during the postoperative period. Regular activity program participation improves physical conditioning, raises the symptom-limited exertional level, lessens post surgical musculoskeletal discomfort, and improves morale. Yet exercise alone without comprehensive secondary prevention and risk factor modification will be no more successful at arresting atherosclerosis than any other single measure. Both operative intervention and vigorous exertion are valuable components of coronary artery disease therapy, but must be part of an all-embracing effort. Whether regular exertion combined with overall risk factor modification will prolong life and reduce future cardiac events or beneficially alter the process of atherogenesis remain areas of avid investigation.

Evaluation of coronary bypass grafts

Coronary artery bypass graft (CABG) surgery is in widespread use. Bypass graft angiography continues to be an integral part of the evaluation of the post-CABG patient. Future methods may include computed tomography and digital subtraction angiography to assist in this evaluation.

Prevention of lipid accumulation in experimental vein bypass grafts by antiplatelet therapy

The ameliorative effect of antiplatelet therapy on atherogenesis of vein grafts was assessed in autologous cephalic veins grafted into femoral arteries of 16 normolipemic and 11 hyperlipemic stump-tailed macaque monkeys. Before grafting, one half of each vein was distended at high pressure (700 mm Hg) and the other half at low pressure (350 mm Hg). Eight normolipemic monkeys were treated with aspirin, 80 mg/day, and dipyridamole, 50 mg/day, and eight were controls. When grafts were harvested at 12 weeks, tissue cholesterol and beta-apoprotein content in grafts from untreated monkeys were significantly higher than in ungrafted, uninjured veins. Antiplatelet therapy eliminated the increase in lipid content of vein segments distended at low pressure, and significantly lowered lipid content of segments distended at high pressure, though not to be control levels of ungrafted veins. Seven of the 11 hyperlipemic monkeys received antiplatelet drugs and four did not. The lipid content of all graft segments was significantly higher than in grafted or ungrafted veins from normolipemic monkeys. Antiplatelet therapy again significantly reduced the lipid content in vein segments distended at both levels of pressure, and also reduced the elevated cholesterol content in ungrafted veins. Although this animal preparation differs in many ways from human coronary bypass operations, these observations may be pertinent to the prevention of atherosclerosis in human vein bypass grafts.

Angiographic changes in internal mammary artery and saphenous vein grafts, two weeks, one year and five years after coronary bypass surgery

Coronary angiography was performed two weeks after coronary bypass surgery on 112/121 consecutive operative survivors (93%), on 97/119 one-year survivors (82%) and on 79/108 five-year survivors (73%). Occlusions of the grafts were uncommon after the first year. The cumulative five-year patency, calculated with the actuarial method, was 89% for internal mammary artery (IMA) grafts and 77% for aortocoronary saphenous vein (SV) grafts. Almost 70% of the SV grafts exhibited a 15-50% reduced diameter after one year and 10% showed progressive narrowing at five years. Diffuse luminal narrowing did not predict graft failure. The incidence of localized narrowings present at two weeks after surgery was, however, significantly higher among SV grafts, which occluded within one year, than among those patent after five years. In 5% of the IMA grafts the diameter was reduced 15-80% after five years. This was related either to obstruction at the anastomotic site or to low-grade proximal coronary stenosis. No less than 12% of the IMA grafts increased 20-50% in diameter as an adaptation to good distal runoff.

Prophylactic coronary artery grafting in patients with few or no symptoms

Fifty-five patients who underwent prophylactic coronary artery grafting were followed for 4 to 8 years. Sixteen patients had no angina, and 39 were in New York Heart Association Functional Class I. Twenty-one patients had single-vessel disease, 13 had double-vessel disease, and 27, triple-vessel disease. A total of 101 grafts were inserted. There were no operative deaths. Two patients suffered a perioperative myocardial infarction (MI), and 3 were reoperated on for persistent bleeding. Early after operation, 9 of the 45 grafts were occluded. At 1 year, 2 patients had occlusion of all grafts, and 1 had similar findings at 5 years. There were 4 late deaths, 3 related to coronary artery disease. Seven patients sustained a late MI. Thirty-one of the 51 survivors (60.8%) seen late (mean, 69.3 months) after operation were free from angina; 14 were in Class I and 6, Class II. It is apparent from this retrospective study that patients such as these stand to benefit little from prophylactic revascularization. Longevity may be increased, however, in patients who are asymptomatic after MI.

Reoperation for coronary graft failure: clinical and angiographic results in 43 patients

Reoperation because of early or late coronary graft failure was performed in 43 patients who were part of a group of 1,985 patients operated on for coronary artery disease and followed for up to 7 years. Considerable variation in the results was noted depending on whether the patients were symptomatic or not before reoperation. Of the symptomatic patients, 85% were asymptomatic late (30 months) after reoperation whereas of those patients reoperated on despite the apparent lack of symptoms, 71.5% remained free from angina later on. Moreover, patency rate was high (94.4% or 17/18 grafts) in the first group and much lower (38.4% or 5/13 grafts) in those reoperated on solely on the basis of an early angiogram showing malfunctioning grafts. Patency rate was higher when the graft was totally replaced (92.3% or 12/13 restudied) rather than repaired simply through interposition of a segment of vein (37.5% or 3/8). It is apparent that results of reoperation in symptomatic patients are identical to those of an initial revascularization. On the other hand, patients who are asymptomatic despite early evidence of malfunctioning grafts should be reoperated on only when optimal angiographic conditions are present, that is, a coronary artery that is a good size, severely narrowed, and supplying a large myocardial area.