Endothelin-1 (ET-1), a vascular endothelium-derived peptide, regulates microcirculation by modulating Ca2+ ion channels. Intravitreally injected ET-1 constricts retinal vessels and reduces blood flow in the optic nerve capillaries. We examined the antagonistic effect of a calcium-ion channel blocker, nicardipine, on ET-1 effects on visual evoked potential (VEP). ET-1 (10(-6); 10 microL) was injected into the posterior vitreous of rabbit eyes. Intravenous nicardipine (20 micrograms/kg) was also given, and VEP was monitored for 2 hours following injection. Thirty minutes after injection, ET-1 had reduced VEP amplitude to 42.6% of the baseline level. The reduction effect continued for the remainder of the study. Nicardipine suppressed the ET-1-induced reduction of VEP amplitude (P < 0.05, Scheffe). The vasospasm produced by ET-1, which reduces the VEP amplitude, involves the CA2+ ion channel. Since nicardipine interferes with the activity of ET-1, we believe that Ca2+ channel blockers can be useful in the treatment of ischemic retinal and optic nerve disorders that are related to abnormal ET-1 production.

Animals↗

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Measurement of activities in two different angiotensin II generating systems, chymase and angiotensin-converting enzyme, in the vitreous fluid of vitreoretinal diseases: a possible involvement of chymase in the pathogenesis of macular hole patients.

PURPOSE: To investigate possible involvement of chymase and angiotensin-converting enzyme (ACE) in the pathogenesis of vitreoretinal diseases, both of which are related to the production of angiotensin II. METHODS: We measured chymase and ACE activities in the vitreous in the 54 affected eyes of 54 patients who had undergone vitreous surgery for idiopathic macular holes (MH, n = 14), proliferative diabetic retinopathy (PDR, n = 14), idiopathic epiretinal membranes (ERM, n = 13), and rhegmatogenous retinal detachment (RRD, n = 13). RESULTS: Chymase activities in the vitreous from patients with MH, PDR, ERM, and RRD were 1.87 +/- 0.53, 0.06 +/- 0.04, 0.40 +/- 0.12, and 0.08 +/- 0.03 (mean +/- SE) mU/mg protein, respectively, and ACE activities in the vitreous humor were 0.18 +/- 0.09, 0.30 +/- 0.07, 0.01 +/- 0.01, and 0.03 +/- 0.02 (mean +/- SE) mU/mg protein, respectively. Chymase activity was significantly elevated in MH among these diseases (p < 0.01, Scheffe), and ACE was significantly activated in PDR compared to ERM and RRD (p < 0.05, Scheffe). CONCLUSIONS: Our results suggest that two different angiotensin II generating systems are activated in human vitreous humor; an increased activity of chymase may play a possible role in the formation of macular holes.

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Total extracardiac right heart bypass using a polytetrafluoroethylene graft.

BACKGROUND: With regard to hemodynamics and late arrhythmias, total cavopulmonary connection has been accepted as a superior technique as compared to Fontan type procedures. However, intra-atrial baffles for lateral tunnel or conduit remain construction retain some similar disadvantages. PATIENTS AND METHODS: As an alternative to total cavopulmonary connection, total extracardiac right heart bypass using a polytetrafluoroethylene tube for the inferior vena cava to pulmonary artery connection may obviate some problems. Five patients with complex heart disease necessitating one ventricle repair underwent this procedure successfully. RESULTS: Aortic cross-clamp time ranged from 0 to 24 minutes (mean = 15.8 min). No case required takedown or an additional step. Although the follow-up periods have been relatively short (mean = 19 months), all patients are well and no arrhythmic event or thromboembolic episode has occurred. CONCLUSIONS: As a simple, safe, and reproducible procedure, total extracardiac right heart bypass is an alternative to Fontan or total cavopulmonary connection procedure.

Blood Vessel Prosthesis↗

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Refractoriness to platelet transfusion following double valve replacement in an ITP patient who had undergone splenectomy.

Reports of patients with idiopathic thrombocytopenic purpura (ITP) undergoing cardiac surgery are rare, and almost all of the reported cases required platelet transfusion. ITP patients, especially those having a history of splenectomy or a history of heavy bleeding, may have to undergo multiple platelet transfusions. Such transfusions may induce alloimmunization against the human leukocyte antigen (HLA) and result in refractoriness to subsequent platelet transfusions. We report a case of a 63-year-old female with ITP, with a history of splenectomy and multiple platelet transfusions, who underwent aortic and mitral valve replacement. Although corticosteroid administration, high-dose immunoglobulin therapy, and repeated platelet transfusion led to a temporary increase in platelet count and successful hemostasis, refractoriness to platelet transfusion occurred postoperatively because of the presence of the anti-HLA antibody. In addition, the patient showed complications of pyothorax. Corticosteroids might have exerted an inhibitory influence on the occurrence of pyothorax.

Aortic Valve↗

PubMedDate not supplied

Disseminated cholesterol embolism after coronary artery bypass grafting.

Blue toe syndrome caused by cholesterol emboli is a relatively benign disease. However, disseminated cholesterol embolism is a life-threatening condition. We describe here the case of a 71-year-old female admitted because of anterior chest pain and intermittent claudication. Following cardiac catheterization, warfarin potassium was administered. However, the patient's toes soon darkened bilaterally, and BUN and creatinine levels increased from the normal value. Skin discoloration and renal failure were improved after stopping warfarin potassium administration. The patient underwent coronary artery bypass grafting and left femoropopliteal bypass. Cerebral infarction and renal failure occurred postoperatively due to disseminated cholesterol embolism. The patient died from renal failure on the 16th postoperative day without regaining consciousness following surgery. For high risk patients, interventional procedures to the ascending aorta must be avoided. When CABG cannot be avoided for coronary revascularization, off-pump bypass and use of arterial grafts are recommended.

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