Platelet induced aggravation of acute ischaemia in an isolated rabbit heart model.

In isolated coronary ligated rabbit hearts the effects of washed human platelets on the size of the epicardial ischaemic area and on recovery from ischaemia during 60 min of reperfusion was evaluated by endogenous NADH-surface-fluorescence photography. Infusion of washed human platelets to non-ischaemic control hearts produced a decrease in left ventricular pressure to 64(3)% of control (n = 4), no change in global coronary flow rate, no retention of platelets (recovery 108(9)%), and no alteration in basal NADH-fluorescence. When platelets were infused into coronary ligated hearts, however, the size of the epicardial ischaemic area was significantly enhanced to 127(8)% (n = 5) of control. Moreover, this increase in size was negatively correlated with the recovery of platelets in the coronary effluent: the lower the recovery rate the larger the ischaemic area (y = 253-1.44x, r = -0.855, n = 15, p less than 0.001). When platelet infusion was stopped after 30 min the enlargement of the ischaemic area seemed to be reversible. When the coronary ligature was released, however, and the ischaemic myocardium reperfused the recovery from ischaemia was retarded in the platelet treated hearts as shown by functional (left ventricular pressure and flow) and metabolic (NADH-fluorescence) indices. Thus it is directly shown for the first time in an isolated in vitro heart preparation that platelets aggravate myocardial ischaemia.

Tricuspid valve repair in right-sided endocarditis.

BACKGROUND AND AIMS OF THE STUDY: Tricuspid valve endocarditis traditionally has been treated with either valve resection or valve replacement. To avoid implantation of foreign material in an infected area and to circumvent anticoagulation, tricuspid valve repair was applied and the results assessed. METHODS: Tricuspid valve repair was performed in five patients with right-sided endocarditis. All patients had tricuspid regurgitation grade 3-4 on preoperative transesophageal echocardiography, and developed progressive deterioration associated with heart failure. The indications for surgery were congestive heart failure, persistent sepsis, recurrent emboli, concomitant left-sided endocarditis, and fungal infection. Surgical procedures included cusp resection, annular plication and annuloplasty, pericardial patch replacement, and construction of artificial chordae. RESULTS: There were no hospital deaths and major associated morbidity. Follow up is complete at a mean of 20.4 months. There were no reoperations or cases of recurrent infections. All patients are in NYHA class I-II. Postoperative echocardiography revealed no signs of major valvular dysfunction. CONCLUSIONS: Valve repair in right-sided endocarditis is a relatively new application for repair techniques, but may become an attractive alternative to tricuspid valve excision or prosthetic valve replacement.