Early and late results of coronary artery bypass in patients with hyperlipoproteinemia

Treatment of hypercholesterolemia with heparin-induced extracorporeal low-density lipoprotein precipitation (HELP)

Familial hypercholesterolemia (FH) can cause early disability and death from premature atherosclerotic cardiovascular disease. Patients homozygous for the disease have very high plasma cholesterol, extensive xanthomatosis, and die from atherosclerosis in childhood or early adulthood. Past attempts to improve the prognosis included removal of cholesterol from the circulation by ileal bypass or biliary diversion. Neither treatment was successful. Direct removal by plasmapheresis of low-density lipoprotein (LDL), the primary carrier of cholesterol in plasma, was first performed on an FH homozygous patient in 1966. The treatment was well tolerated and led to rapid diminution of xanthomas. Other experimental treatments included selective LDL apheresis with monoclonal or polyclonal antibody affinity columns. A method for selective LDL apheresis was developed in 1983 by Armstrong, Seidel, and colleagues based on heparin precipitation of LDL at low pH. This method, called HELP, removes all apolipoprotein B-containing lipoproteins including LDL and lipoprotein (a), as well as some fibrinogen. LDL apheresis by HELP is well tolerated; the incidence of side effects is low, and the treatment has been associated with regression of cardiovascular disease. LDL apheresis, rather than liver transplantation, is the treatment of choice for patients with severe, life-threatening hypercholesterolemia which does not respond to diet and drug therapy.

Critical role of pulmonary angiography in the diagnosis of pulmonary emboli following cardiac surgery

This study was conducted to identify patients at high risk of the development of Pulmonary Embolism (PE) after open heart surgery, to evaluate pertinent diagnostic methods, and to assess the mortality associated with this complication. We evaluated the records of 2,551 consecutive patients who underwent open heart surgery over a 10-year period to identify those patients in whom PE developed. All surgical reports, ventilation/perfusion scans, pulmonary angiograms, and autopsies from the same period were also reviewed. Preoperative and postoperative risk factors for pulmonary embolism were also analyzed, as well as the outcome of this complication in each type of surgical procedure. Pulmonary embolism was identified in 69 (2.7%) patients after open heart surgery, in 43 (62.3%) of whom the diagnosis was established within the first week of surgery. Factors associated with high incidence for PE were hyperlipidemia, congestive heart failure and heparin-induced thrombocytopenia (P < 0.001); obesity and prolonged mechanical ventilation (P < 0.005); and prior right heart catheterization by the femoral approach and prior PE and/or deep vein thrombosis (P < 0.05). The diagnosis of PE was established by a high-probability ventilation/perfusion scan in 25 patients, by pulmonary angiography in 42 (29 of whom had prior V/Q scan read as intermediate or low probability for PE) and by autopsy in two patients. The mortality rate in patients who had PE was 7.2%, while in those without this complication it was 3.2%. These findings suggest that aggressive approach for the diagnosis of PE by pulmonary angiography whenever the V/Q scan is not read as high probability is crucial in patients with recent open heart surgery; such approach may identify patients with PE at an early stage and may have an impact in reducing mortality incurred by this complication. This diagnostic assessment should be emphasized in the perioperative period, especially in patients with multiple significant and identifiable risk factors for PE.

Pulmonary embolism after cardiac surgery

OBJECTIVES

We examined the incidence of pulmonary embolism after cardiac surgery.

BACKGROUND

Because venous thromboembolism is considered to be an uncommon complication after cardiac surgery, its incidence was documented in a consecutive series of 1,033 patients who underwent cardiac surgery over a 5-year period.

METHODS

Parallel cohorts of patients in a tertiary referral center were evaluated and the incidence of pulmonary embolism was compared in subgroups of patients undergoing coronary bypass surgery, valve surgery and combined procedures.

RESULTS

Pulmonary embolism developed in 33 (3.2%) of the 1,033 cardiac surgical patients, within 2 weeks of a coronary bypass operation in most; it did not develop in any patient who had isolated valve replacement surgery (p < 0.05). The diagnosis of pulmonary embolism was established by pulmonary angiography in 24 patients, ventilation/perfusion lung scan in 3, postmortem examination in 5 and clinical examination in 1 patient. Important risk factors for pulmonary embolism included prolonged postoperative recovery, obesity and hyperlipidemia. The mortality rate was 18.7% in patients with in contrast to 3.3% in those without pulmonary embolism (p < 0.01).

CONCLUSIONS

Although pulmonary embolism is rare after isolated valve replacement, it is not an uncommon complication after coronary bypass surgery.

Pulmonary embolism in the cardiac surgical patient

Pulmonary embolism (PE) is thought to occur infrequently after cardiac operations, possibly because systemic heparinization during cardiopulmonary bypass prevents deep vein thrombosis. This retrospective study was undertaken to determine the actual incidence of PE after cardiac operations and to identify risk factors. Between January 1, 1985, and December 31, 1989, 5,694 adult patients (greater than 18 years old) had open heart operations at the Johns Hopkins Hospital. Thirty-two patients (20 men and 12 women) had PE within 60 days of operation, an overall PE incidence of 0.56%. The diagnosis of PE was established by ventilation/perfusion scan, pulmonary angiogram, or autopsy. Mortality among patients with PE was 34%. Using a case-control method, preoperative and postoperative risk factors for PE were identified by multivariate and multiple logistic regression analyses. Preoperative risk factors included bed rest (p less than 0.003), prolonged hospitalization before operation (p less than 0.004), and cardiac catheterization performed through the groin within 15 days before operation (p less than 0.01). Post-operative risk factors were congestive heart failure (p less than 0.008), prolonged bed rest (p less than 0.05), and deep vein thrombosis (p less than 0.03). This study demonstrates that PE is an unusual complication after cardiac operations, has a high mortality rate, and is often related to perioperative immobility and recent groin catheterization. These results also suggest that minimizing preoperative hospital stay may be important in PE prophylaxis.

Autopsy findings in two patients with homozygous familial hypercholesterolemia. Special references to apolipoprotein B localization and internalization defect of low density lipoprotein

We have experienced two autopsy cases of familial hypercholesterolemia of type IIa homozygote, one was a 21-year-old female with a defect in the internalization of low density lipoprotein which is thought to be the first autopsy report in the world, and the other was a 31-year-old male with a receptor negative for low density lipoprotein. Autopsy findings, in addition to marked skin xanthomatosis, disclosed reversed distribution of the aortic atherosclerosis, diffuse atherosclerotic narrowing of coronary arteries which led to myocardial necrosis, xanthomatous aortic and mitral valve, and much less severity of cerebral arteries rather than that of aorto-coronary atherosclerosis. We have examined the apolipoprotein B accumulation on these aortas, coronary arteries, and cardiac valves, which showed better correlation between apolipoprotein B deposit areas and preferential accumulation of Alcian blue positive areas suggested to contain sulfate glycosaminoglycan, and documented very rare localization of renal and osseous xanthomas in a patient with internalization defect of low density lipoprotein.

Coronary artery bypass grafting in young patients under 36 years of age

Results of coronary artery bypass graft (CABG) surgery in patients under age 36 who were operated upon between 1970 and 1980 at two large medical centers were compared to matched control patients, age 45 to 59 years, and 60 years and over. Patient follow-up ranged from one to 13 years (average five years). Event-free survival was significantly worse in the young group (37 percent) vs the middle aged group (61 percent, p less than 0.01) and vs the elderly group (59 percent, p less than 0.02). Failure of the operation was due to failure to improve or worsening of Canadian Cardiovascular Society anginal class, need for reoperation, subsequent myocardial infarction, or death due to cardiac causes. Risk of failure of CABG surgery in young patients was increased with the presence of cardiac risk factors. Because of the high rate of long-term failure of CABG surgery in young patients, its use in this group needs to be reevaluated relative to current aggressive medical therapy for angina.

Young adults with coronary atherosclerosis: 10 year results of surgical myocardial revascularization

This study reviews data on 107 patients, aged 35 years or younger, who underwent surgical coronary revascularization from 1971 to 1975. Early clinical events included one operative death and five nonfatal perioperative myocardial infarctions. Late follow-up (mean interval after operation 115 months) demonstrated actuarial survival rates of 94% at 5 years and 85% at 10 years. Fifteen late deaths, 23 nonfatal myocardial infarctions, 13 reoperations and return of severe angina in 10 patients were considered late clinical events. Actuarial survival free of early or late clinical events was 77% at 5 years and 53% at 10 postoperative years. Testing of clinical, angiographic and operative variables for influence on survival and event-free survival showed that survival was decreased by multivessel disease and impaired left ventricular function; event-free survival was decreased by a family history of coronary disease and cigarette smoking. Both survival and event-free survival were decreased by diabetes and elevated serum cholesterol. Postoperative cardiac catheterization (64 patients, mean postoperative interval 47 months) demonstrated that mammary artery graft patency (25 of 27, 93%) exceeded vein graft patency (49 of 88, 56%, p less than 0.01). The atherogenic diatheses of young adults may compromise the operative result, whereas use of internal mammary artery grafts may enhance the palliation of bypass surgery.

Hyperlipoproteinemia as a significant risk factor for pulmonary embolism in patients undergoing coronary artery bypass grafting

A five-year (1975 through 1979) retrospective analysis of all cardiac surgical patients who sustained a postoperative pulmonary embolism was undertaken, and lipoprotein profiles of these patients were evaluated. Twenty-six patients (20 men and 6 women) were identified who had definite clinical, laboratory, and radiological evidence of pulmonary embolism in the postoperative period. Twenty had undergone coronary artery bypass grafting, and the remaining 6 had undergone other cardiac surgical procedures. Of the 20 patients who had coronary bypass, 19 (95%) were found to have hyperlipoproteinemia (14 patients with type II and 5 with type IV). There were 4 hospital deaths (15%), all related to pulmonary embolism. The 4 patients had undergone coronary bypass procedures, and all had type II hyperlipoproteinemia. Since patients with hyperlipoproteinemia made up less than 10% of the coronary bypass population, the incidence of pulmonary embolism in this group is highly significant (p less than 0.001). Experimental evidence has shown that patients with hyperlipoproteinemia, especially type II, have increased platelet adhesiveness and aggregation, and coagulation abnormalities consistent with a hypercoagulable state. This retrospective study clinically confirms that finding and suggests that early postoperative anticoagulation therapy may be indicated in patients with hyperlipoproteinemia, particularly type II, to reduce thromboembolic complications.