P Van Cauwelaert

Foam cell replication and smooth muscle cell apoptosis in human saphenous vein grafts

Occlusion of saphenous vein grafts is a major problem after coronary artery bypass grafting. Segments of occluded and suboccluded implanted aortocoronary grafts were obtained during re‐intervention bypass grafting in 47 patients yielding a total of 80 vein grafts. The grafts were studied by immunohistochemistry for smooth muscle cells (ÉL‐SMC actin), macrophages (HAM56), cell replication (PCNA, Ki‐67) and transmission and scanning electronmicroscopy (TEM, SEM). In 81% of the examined grafts the (sub)occlusion was due to a myo‐intimal thickening and an associated luminal accumulation of foam cells and mural thrombi. The foam cells were constantly found at the luminal site of the myo‐intimal thickening and within the luminal part of adherent thrombi. Transmission electronmicroscopy demonstrated phagocytosis of platelets and platelet fragments by the foam cells. A significant fraction of the foam cells demonstrated nuclear immunoreactivity for Ki‐67 and PCNA. The myo‐intimal thickening of the vein grafts was composed of smooth muscle cells lying in a fibrous tissue matrix. The smooth muscle cells were surrounded by prominent basal lamina and showed ultrastructural features of apoptosis. Our results support the hypothesis that phagocytosis of lipid rich platelets by monocytes set up a mechanism for foam cell formation and replication in human saphenous vein grafts. The transformation of a smooth muscle cell rich myo‐intimal thickening towards a fibrous, cell poor intimal thickening could be induced by progressive smooth muscle cell loss through apoptosis.

Priming solutions for cardiopulmonary bypass: Comparison of three colloids

The present study was designed to compare the differences in the clinical effects of three colloidal solutions, albumin, urea-linked gelatin, and succinyl-linked gelatin, when used as priming fluids for cardiopulmonary bypass (CPB) under alpha-stat conditions. A consecutive series of 105 patients scheduled for cardiac surgery were randomized into three identically managed groups, except for the CPB prime. Variables relating to acid-base status, oncotic activity, metabolism, coagulation, and postoperative evaluation were measured. Marked differences in acid-base status, colloid osmotic pressure, additional prime requirements, blood lactate, urine output, and the need for buffer solutions occurred among groups, with the succinyl-linked gelatin group having better results than the other groups. Changes in hemodynamics, oxygen consumption, and blood-glucose levels during CPB did not vary among groups. There were also no important intergroup differences in hematologic and clotting variables or postoperative parameters such as blood loss or use of blood products. Electrolyte changes were similar except for a significant increase in ionized calcium that occurred in the urea-linked gelatin group after bypass. The results indicate that succinyl-linked gelatin is an adequate and safe alternative to human albumin for use as a colloid during CPB under alpha-stat conditions.

TIMING OF AORTIC VALVE REPLACEMENT IN ELDERLY PATIENTS WITH SYMPTOMATIC AORTIC VALVE DISEASE USING OUTPATIENT CLINICAL PARAMETERS

Abstract Objective: To determine by how far worsening outpatient clinical parameters can affect outcome after aortic valve replacement, in patients with preserved left ventricular function and symptomatic aortic valve disease. Patients and methods: Five hundred patients with aortic valve disease underwent aortic valve replacement using a bioprosthesis. In 348 patients, another procedure was added. The preoperative outpatient parameters were investigated for their effect on hospital and long-term mortality. A Fisher exact, Kaplan-Meier univariate and Cox proportional hazard analysis were used. Results: A retrospective follow-up of 2022 patient years was obtained. Five preoperative parameters were found to be more present in patients with a decreased left ventricular function: 1) severity of symptoms, 2) previous myocardial infarction, 3) conduction defects, 4) aortic valve regurgiation and 5) increasing need for medication. In patients with an ejection fraction of 50% or more, logistic regression analysis showed that hospital mortality increased with need for medication (p=0.004), previously performed CABG (0.015), increase in symptoms (p=0.018) and myocardial infarction (p=0.034). A Kaplan-Meier analysis revealed aortic valve regurgitation (p=0.017) and increased need for medication (p=0.012) as significant on long-term survival. Presence of a previous myocardial infarction showed a trend (p=0.062). A Cox’ proportional hazard analysis showed for global mortality increased need for medication (p=0.010) and previous myocardial infarction (p=0.018) as independent factors and for long-term mortality, this was aortic valve regurgitation (p=0.001). Conclusions: Results after aortic valve replacement deteriorate with the presence of valve regurgitation, a preoperative myocardial infarction, increasing need for medication or severity of symptoms, even for an ejection fraction of 50% or more. Anamnesis with special care to the degree of symptoms and increasing need for medication early in the valve disease could lead to early referral, thereby reducing number of patients with severe symptoms and improving postoperative results.