Coronary artery bypass grafting in familial hypercholesterolemia

Resilience of the Internal Mammary Artery to Atherogenesis: Shifting From Risk to Resistance to Address Unmet Needs

Fueled by the global surge in aging, atherosclerotic cardiovascular disease reached pandemic dimensions putting affected individuals at enhanced risk of myocardial infarction, stroke, and premature death. Atherosclerosis is a systemic disease driven by a wide spectrum of factors, including cholesterol, pressure, and disturbed flow. Although all arterial beds encounter a similar atherogenic milieu, the development of atheromatous lesions occurs discontinuously across the vascular system. Indeed, the internal mammary artery possesses unique biological properties that confer protection to intimal growth and atherosclerotic plaque formation, thus making it a conduit of choice for coronary artery bypass grafting. Its endothelium abundantly expresses nitric oxide synthase and shows accentuated nitric oxide release, while its vascular smooth muscle cells exhibit reduced tissue factor expression, high tPA (tissue-type plasminogen activator) production and blunted migration and proliferation, which may collectively mitigate intimal thickening and ultimately the evolution of atheromatous plaques. We aim here to provide insights into the anatomy, physiology, cellular, and molecular aspects of the internal mammary artery thereby elucidating its remarkable resistance to atherogenesis. We propose a change in perspective from risk to resilience to decipher mechanisms of atheroresistance and eventually identification of novel therapeutic targets presently not addressed by currently available remedies.

Coronary artery bypass grafting in a 12-year-old girl with familial hypercholesterolemia

As CABG operation is indicated in children with familial hypercholesterolemia, it seems that bilateral internal thoracic arteries are the preferred grafts, taking into consideration its superiority over venous graft regarding patency and growth.

Coronary artery bypass grafting in children for atheromatous and non-atheromatous lesions

Coronary artery involvement in children is an uncommon but well-recognized clinical entity. It is an important cause for sudden cardiac death in children. Diagnosis requires a high index of suspicion since it has serious consequences when missed. Presentation of coronary artery abnormality is very variable due to congenital as well as acquired aetiology. In this review, we have described the different causes that require coronary artery bypass grafting in children and their pathogenesis. The nuances of conduit selection, graft behaviour in children, patency rates and long-term outcomes in children undergoing coronary artery bypass have also been discussed.

Heterozygous Familial Hypercholesterolemia With APOE Haplotype: A Prospective Harbinger of a Catastrophic Cardiovascular Event

We report a very young man with heterozygous familial hypercholesterolemia (FH) with APOE haplotype and a significant cardiac family history who underwent cardiac catheterization for intermittent episodes of exertional dyspnea and was noted to have a severe triple vessel coronary artery disease (CAD). He underwent coronary artery bypass graft (CABG) surgery which was uneventful. He was discharged on antiplatelet, beta blocker, nitrate, and statin. On routine health maintenance evaluation, he had no cardiac complaints and had been tolerating well his activities of daily living.

Surgical Challenges of Familial Hypercholesterolemia

A 21-year-old patient with familial hypercholesterolemia presented with angina caused by ostial stenosis of the left internal mammary artery and severe calcific aortic stenosis with small aortic root 9 years after coronary revascularization. The ostium of the left internal mammary artery was enlarged using a saphenous vein patch through a left supraclavicular incision, which improved left ventricular function. Successful aortic valve replacement with posterior aortic root enlargement was subsequently performed. The surgical management of this condition is discussed briefly.

New mouse model of vein bypass graft atherosclerosis

Animal models of vein graft disease are used as preliminary tools to study and understand the pathogenesis of the disease in humans and improve its diagnosis, prevention and therapy. Several animal models that manifest lesions resembling neointimal hyperplasia of human vein grafts have been developed, but there are limitations in studying the mechanism of this disease in these models. We previously established a mouse model of vein bypass graft atherosclerosis that allows us to take advantage of transgenic and knockout techniques. Using this model, we studied the pathogenesis of vein graft atherosclerosis. The lesion in the grafts was characterised by mononuclear cell infiltration followed by smooth muscle cell (SMC) proliferation and matrix protein deposition, which is similar to the human lesion. Studies of the molecular mechanism of pathogenesis in this model revealed that physical force initiated signal pathways, particularly mitogen-activated protein kinases (MAPK), leading to vascular cell death and an inflammatory response, followed by SMC proliferation, which contributed to the development of arteriosclerosis. Suramin inhibited SMC migration and proliferation in vivo and in vitro by blocking platelet-derived growth factor (PDGF)-initiated PDGF receptor activation and MAPK-AP-1 signalling, and was also effective in inhibition of neointima hyperplasia in mouse vein bypass grafts. This new mouse model of vein bypass graft atherosclerosis affords us with a valuable new approach to attain further understanding of the mechanism of vein graft disease with the use of transgenic mice, and in evaluating the effects of drugs and gene therapy on vascular diseases.

Homograft Replacement of the Calcified Aortic Root in Familial Hypercholesterolemia

A 39-year-old woman with a known history of homozygous familial hypercholesterolemia was admitted with chest discomfort. Preoperative echocardiography and coronary angiography showed a heavily stenotic aortic valve as well as a calcific hypoplastic aortic root. Aortic root replacement using an aortic homograft was done.

Lipoprotein(a): an emerging cardiovascular risk factor

Lipoprotein(a) is a cholesterol-enriched lipoprotein, consisting of a covalent linkage joining the unique and highly polymorphic apolipoprotein(a) to apolipoprotein B100, the main protein moiety of low-density lipoproteins. Although the concentration of lipoprotein(a) in humans is mostly genetically determined, acquired disorders might influence synthesis and catabolism of the particle. Raised concentration of lipoprotein(a) has been acknowledged as a leading inherited risk factor for both premature and advanced atherosclerosis at different vascular sites. The strong structural homologies with plasminogen and low-density lipoproteins suggest that lipoprotein(a) might represent the ideal bridge between the fields of atherosclerosis and thrombosis in the pathogenesis of vascular occlusive disorders. Unfortunately, the exact mechanisms by which lipoprotein(a) promotes, accelerates, and complicates atherosclerosis are only partially understood. In some clinical settings, such as in patients at exceptionally low risk for cardiovascular disease, the potential regenerative and antineoplastic properties of lipoprotein(a) might paradoxically counterbalance its athero-thrombogenicity, as attested by the compatibility between raised plasma lipoprotein(a) levels and longevity.

Aortic valve replacement for the calcified ascending aorta in homozygous familial hypercholesterolemia

A 72-year-old woman who had been diagnosed as homozygous familial hypercholesterolemia was admitted for chest discomfort. Computed tomography and cardiac catheterization revealed severe calcification of the aortic root and a high grade stenosis of the proximal right coronary artery. Aortic valve replacement concomitant with coronary artery bypass was done using temporary hypothermic circulatory arrest. This is preferred method when dealing the calcified aorta.

Rapid development of vein graft atheroma in ApoE-deficient mice

Several animal models manifesting lesions resembling neointimal hyperplasia of human vein grafts have been developed, but no spontaneous atheromatous lesions in their vein grafts have been observed. We developed and here characterize a new animal model of vein graft atheroma, a maturated atherosclerotic plaque, in apoE-deficient mice. The lesion displayed classical complex morphological features and heterogeneous cellular compositions and consisted of a fibrous cap, infiltrated mononuclear cells, foam cells, cholesterol crystal structure, necrotic core with calcification, and neovasculature. Cell component analysis revealed smooth muscle cells (SMCs) localized in the cap region, macrophages which made up a large portion of the lesions, and CD4+ T cells scattered under the cap. Importantly, apoptotic/necrotic cells determined by TUNEL assay in vein grafts into apoE-/- mice were significantly higher than wild-type mice, although a similar number of proliferating cell nuclear antigen-positive cells in both types of lesions was found. Interestingly, vascular SMCs cultivated from aortas of apoE-deficient mice showed a high rate of spontaneous apoptosis/necrosis and a higher rate of cell death stimulated by a nitric oxide donor, sodium nitroprusside, H(2)O(2), and oxidized low density lipoprotein (LDL), although no difference in proliferation of both SMCs incubated with platelet-derived growth factor, angiotensin II, LDL, and oxidized LDL was seen. Thus, the pathogenic mechanisms of vein graft atheroma involve increased intimal cell death initiated by biomechanical stress and amplified by hypercholesterolemia, which leads to continuous recruitment of blood mononuclear cells to constitute atheromatous lesions. This mouse model resembling human vein graft disease has many advantages over other animal models.

Coronary artery bypass surgery with arterial grafts in familial hypercholesterolemia

OBJECTIVE

Familial hypercholesterolemia is a dominantly inherited disorder caused by mutations at the locus for the low-density lipoprotein receptor and is frequently associated with premature coronary artery disease. This study was performed to determine whether arterial grafting was associated with long-term benefits for patients with familial hypercholesterolemia.

METHODS

During the past 18 years, 101 patients with heterozygous familial hypercholesterolemia underwent primary coronary artery bypass grafting, with one hospital death. Group 1 patients (n = 31) received only saphenous vein grafts. Group 2A patients (n = 47) received one internal thoracic artery graft and supplemental vein grafts, and group 2B patients (n = 23) had multiple arterial grafts. After operation, all patients received diet therapy and intensive cholesterol-lowering drug therapy. Thirteen patients received low-density lipoprotein apheresis.

RESULTS

During a mean follow-up period of 95 months, 8 patients died, 9 underwent reoperation, and 12 received catheter intervention. The overall survival was 82% (95% confidence limits, 65%-97%) at 18 years after operation. The survival in group 2 was higher than that found in group 1 (P =.01). The overall freedom from major cardiac events (myocardial infarction, cardiac death, reoperation, and catheter intervention) was 57% (95% confidence limits, 40%-74%) at 16 years after operation. The freedom from reoperation in group 2 was higher than that found in group 1 (P =.03). There was no difference in the survival or freedom from major cardiac events between groups 2A and 2B.

CONCLUSION

Arterial grafting improved the long-term freedom from reoperation in patients with familial hypercholesterolemia. Additional benefit of multiple arterial grafting could not be identified.

Arterial revascularization. 18-year experience with coronary artery bypass grafting in familial hypercholesterolemia

Familial hypercholesterolemia is characterized by a high plasma level of cholesterol and is frequently associated with rapidly progressing coronary heart disease. The internal thoracic artery is recognized as the conduit of choice for coronary artery bypass grafting. This study was performed to determine whether multiple arterial grafting was associated or not with additional benefits for patients with familial hypercholesterolemia. Between June 1980 and March 1998, 95 patients with familial hypercholesterolemia. underwent a total of 103 coronary artery bypass procedures with one hospital death. The patients were divided into 3 groups according to the type of bypass graft. Group 1 included 31 patients with only saphenous vein grafts; Group 2,48 patients with one arterial graft and supplemental vein grafts; and Group 3, 24 patients with multiple arterial grafts. The overall actuarial survival rate was 90.9% at 10 years and 81.8% at 18 years. The overall actuarial freedom from recurrent angina was 68.9% at 10 years and 55.8% at 16 years. The actuarial survival rate in group 2 was higher than that in Group 1 (p < 0.05). There was no difference in the actuarial survival or in the freedom from cardiac events between Group 2 and Group 3. Single arterial grafting improved the long-term survival in patients with familial hypercholesterolemia. However, no additional benefit from multiple arterial grafting was identified.

Early morphology of accelerated vein graft atheroma in experimental vein grafts

Vein grafts fail because of the development of intimal hyperplasia and atheroma. Recent experimental evidence suggests that the presence of hypercholesterolemia induces a three-fold increase in intimal hyperplasia with early atheroma development within 4 weeks of implantation. We have previously demonstrated endothelial cell preservation and a short-lived (3-day) polymorphonuclear leukocyte infiltrate in vein grafts. The aim of this study is to define the early morphology and ultrastructure of vein grafts implanted into a hyperlipidemic environment to provide a pathological foundation on which to examine the cellular and molecular events that determine this accelerated response. Twenty-one male New Zealand White rabbits underwent a right carotid interposition bypass graft using the ipsilateral external jugular vein; all animals received a 1% cholesterol diet for 4 weeks prior to surgery and continuing postoperatively until harvest. Animals (n = 3 per time point) were sacrificed at 60 min, 1 day, 3 days, 5 days, 7 days, 14 days, and 28 days postoperatively for scanning and transmission electron microscopy of the vein grafts. No concurrent controls were employed. The results of this study suggest that in the presence of hypercholesterolemia, the pathophysiological processes involved in the vein graft are similar to those reported for noncholesterol-fed animals. There is a sustained subendothelial response with the prolonged presence of macrophages and cellular debris and the accumulation of foam cells.

Usefulness of lipids, lipoprotein(a) and fibrinogen measurements in identifying subjects at risk of occlusive complications following vascular and endovascular surgery

The study was designed to establish the usefulness of measuring lipoprotein(a) [Lp(a)], total cholesterol, triglycerides, low-density lipoprotein [LDL]-cholesterol, high-density lipoprotein [HDL]-cholesterol, total-to-HDL-cholesterol ratio and fibrinogen in identifying subjects at risk of occlusive complications following vascular and endovascular surgery, including primary successful ileofemoral percutaneous transluminal angioplasty, infrainguinal and aortic bypass graft and carotid endarterectomy. A total of 68 volunteers subjected to vascular and endovascular surgery were recruited to the study. Six months after successful interventions, no occlusive complications verified by angiography were observed in 45 patients (66%; No-restenosis group), whereas significant restenosis or reocclusion occurred in 23 patients (34%; Restenosis group). Significant lower concentrations of Lp(a) (p=0.032), total cholesterol (p<0.0001), LDL-cholesterol (p=0.001) and total-to-HDL-cholesterol ratio (p<0.0001) and higher concentrations of HDL-cholesterol (p=0.048) were observed in the No-restenosis group compared to the Restenosis group. The concentrations of triglycerides (p=0.080) and fibrinogen (p=0.510) did not differ significantly between groups. In multivariate discriminant analysis, the best predictors of restenosis or reocclusion were in decreasing order: LDL-cholesterol, Lp(a), total-to-HDL-cholesterol ratio, HDL-cholesterol and total cholesterol. A statistical difference of particular interest was observed in the overall distribution of Lp(a) concentrations between groups (p<0.0001), occlusive complications being unlikely to occur in patients with Lp(a) concentrations below 50 mg L(-1). The potential interference from a concurrent acute phase response, the most common source of elevation of Lp(a) in humans, was less likely in view of the absence of differences in erythrocyte sedimentation rate between the No-restenosis and Restenosis groups (p=0.463). In conclusion, the results of the present investigation point to a definite role of the combined measurements LDL-cholesterol, Lp(a), total-to-HDL-cholesterol ratio, HDL-cholesterol and total cholesterol in the identification of subjects at risk of occlusive events following vascular and endovascular surgical procedures.

Coronary artery bypass grafting in patients in their third decade of life

BACKGROUND AND AIM

Coronary artery disease (CAD) and coronary artery bypass grafting (CABG) in young patients are different than their older counterparts. The purpose of this study is to more fully define the issues of CABG in patients in their third decade of life.

METHODS

The medical records from all patients under forty years of age undergoing CABG at Allegheny University Hospital, Hahnemann Division, Philadelphia, PA from July 1990 to June 1995 were examined. Surgical outcome, psychosocial, and sexual issues were examined. Lipid analyses were compared perioperatively.

RESULTS

There were 43 male and 9 female patients. The mean age was 35 years (23 to 39 years). Risk factors included 43 (83%) patients with a history of smoking, 34 (65%) with familial hypercholesterolemia, 25 (48%) with a family history of CAD, 23 (44%) with hypertension, and 11 (21%) with diabetes. The mean preoperative serum cholesterol was 241 mg/dL. There were no hospital mortalities. Morbidities were found in 18 (35%) patients, including 9 (17%) cardiac, 5 (10%) pulmonary, 3 (6%) infectious, and 1 (2%) renal. In follow-up, three cardiac-related mortalities occurred within five years of surgery. Sixteen patients were readmitted to a hospital for cardiac related causes. Thirty-two (62%) patients failed to return to work, twenty-five (48%) failed to engage in regular exercise, and twenty-four resumed smoking. Psychosocial changes were found postoperatively in thirty (58%) patients. Eight (15%) patients admitted to sexual changes following surgery. Postoperative lipid profiles were minimally altered from preoperative values.

CONCLUSIONS

Surgical revascularization is successful in alleviating symptoms with minimal risk. Postoperatively, a number of cardiac related events occurred. A significant number of patients resume smoking, fail to engage in regular exercise, fail to resume work, and fail to take prescribed lipid-lowering agents. Psychosocial and sexual dysfunctions are prominent.