Platelet aggregation and antiplatelet agents in acute coronary syndromes

Antiplatelet agents are the cornerstone therapy of acute coronary syndromes. In the setting of ST elevation myocardial infarction, antiplatelet therapy prevent the prothrombotic effect of reperfusion therapy including thrombolysis and primary percutaneous coronary intervention. In non ST-elevation acute coronary syndromes, antiplatelet therapy prevent s complete coronary thrombotic occlusion and therefore the occurrence of ST elevation myocardial infarction. Antiplatelet agent benefit is related to the patient's risk profile. It is well established that combined antiplatelet therapy is the most effective in high risk patients. Several important issues have to be faced including the identification of non responders, dose adjustment and the management of temporary interruption of antiplatelet agents in stable coronary artery disease patients.     

Platelet aggregation and vasopressin receptors in patients with diabetes mellitus

Plasma vasopressin, vasopressin-induced platelet aggregation, and platelet vasopressin receptors were investigated in 10 normal subjects and 14 diabetic patients free of microangiopathy. Basal plasma vasopressin concentration was identical in two groups. Platelet aggregation induced by vasopressin as well as by epinephrine was not significantly altered in the diabetic patients. However, exploration of platelet V1-vasopressin receptors revealed in the diabetic group a dramatic reduction in the number of binding sites without alteration of the receptor affinity for tritiated vasopressin. Thus vasopressin-induced platelet aggregation in uncomplicated diabetes mellitus remains normal despite a decrease in the number of vasopressin receptors presumably due to alterations of the platelet membrane structure.     

Platelet aggregation in vasomotor headache

Employing optical density methods, platelet aggregation in response to increasing concentration of ADP was tested in 24 patients with migraine and 15 controls. The migraine patients don't demonstrate platelet hyperaggregability when compared with controls. Platelet aggregate ratio (P.A.R.) was measured in 13 patients and 15 controls by the method of Wu and Hoak: a significant difference was found between and controls. The hyperaggregability found here, even if only for the P.A.R., may help explain the increased incidence of stroke and heart attack in migraine patients that has been reported elsewhere.     

Platelet aggregation independent of adp release or prostaglandin synthesis in patients with Hermansky-Pudlak syndrome

Platelets from patients with the Hermansky-Pudlak (HPS) syndrome are deficient in the storage pool of adenine nucleotides and serotonin. As a result, the storage pool deficient (SPD) platelets develop only single waves of clumping when stimulated by threshold concentrations of aggregating agents which cause irreversible, biphasic aggregation of normal platelets. Yet, patients with HPS either have no bleeding problems or only mild symptoms.In the present study we have evaluated the importance of prostaglandin synthesis and secretion to the irreversible aggregation of HPS platelets. Results of the study demonstrate that aspirin-treated SPD platelets, which cannot form thromboxane or undergo the release reaction on stimulation by arachidonate, can still undergo irreversible aggregation in response to thrombin and ADP if treated first with epinephrine. A mechanism of membrane modulation mediated by a-adrenergic receptors cooperatively linked to the endoperoxide and thromboxane receptor can secure irreversible aggregation of normal or abnormal platelets despite absence of secretion and prostaglandin synthesis.     

Predicted coronary heart disease risk in croatian HIV infected patients treated with combination antiretroviral therapy

We assessed the coronary heart disease (CHD) risk in 130 HIV-infected patients with no major past cardiovascular event treated with combination antiretroviral therapy (CART) between May 2004 and June 2005. We also investigated the association of HIV disease parameters (CD4 + T-cell counts, HIV viral load, AIDS diagnosis, antiretroviral medications and lipodystrophy), demographics, anthropometrics, clinical features, smoking status, dyslipidemia, adherence to the Mediterranean diet, and the metabolic syndrome (MS) to the Framingham risk score. The median 10-year CHD risk was 6.4% (IQR 3.3-13.0) for males and 1.8% (IQR 1.0-6.7) for females. The CHD risk was > or = 10% in 31.1% (32 of 103) males and in 14.8% (4 of 27) females. MS was present in 27 (20.8%) individuals. Participants who met the definition of the MS had a 2.63 times greater chance of having a CHD risk 210% (95% CI, 1.09-6.39; p = 0.032). On multivariable analysis, we found that a CHD risk > or = 10% was associated with: a lowest ever CD4+ T-cell counts of less than 50 per microliter and a past history of AIDS (OR, 6.26; 95% CI, 1.61-24.36; p = 0.008); alcohol consumption 210 g/day (OR, 3.87; 95% CI, 1.56-14.22; p = 0.041); and age 243 years (OR, 1.30; 95% CI, 1.17-1.45; p < 0.001). Interventions to reduce the modifiable cardiovascular risk are needed in Croatian patients treated with CART     

Super-ego in patients with coronary artery disease

In this paper, we explored the super-ego ofpatients with coronary artery disease. Research results have confirmed the initial hypothesis that a significant number of patients with coronary artery disease has rigorous super-ego. Among patients with coronary artery disease (N=50), and control group (N=50), we have found significant differences in the quality of super-ego and ego attitude towards the demands of the super-ego. The results of this research contribute to understanding the impact of psychological factors in coronary artery disease.     

Platelet aggregation during oral contraception

Platelet aggregation has been found to be significantly accelerated with the coagulation-induced Chandler''s tube technique in women taking combined oestrogen-progestin oral contraceptives, though this was less than in the third trimester of pregnancy. Women taking the pure progestogen, chlormadinone acetate, have not shown this change up to the sixth month of study. In contrast the accelerated platelet aggregation resulting from conventional oral contraception became normal one month after changing to the progestogen. There was no change in the platelet aggregation response to adenosine diphosphate (A.D.P.) during oral contraception.     

Platelet aggregation by oral streptococci

One proposed mechanism in the pathogenesis of infective endocarditis is the direct aggregation of platelets by the bacteria causing the disease. Some, but not all, strains of Streptococcus sanguis have been reported to aggregate platelets but the taxonomy of this and related taxa has changed recently. The ability to aggregate platelets by 24 genetically grouped laboratory stock strains was studied along with 8 recent isolates from cases of endocarditis. Strains belonging to S. sanguis could aggregate platelets, but not S. gordonii, "S. parasanguis", S. mitis, S. oralis or related taxa. Also, preliminary data indicate that certain biotypes of S. sanguis lack the ability to aggregate platelets. Of the recent clinical isolates, only 4 aggregated platelets and each of these showed phenotypes typical of S. sanguis. These data suggest that the ability to aggregate platelets is not essential for an organism to be able to cause endocarditis, although it may be a significant virulence factor.     

Platelet glycoprotein IIb/IIIa receptor blockade in coronary artery disease

Glycoprotein IIb/IIIa inhibitors represent a new promising class of antiplatelet medications. Their use in acute coronary syndromes and for patients undergoing percutaneous coronary intervention has been the subject of a number of large controlled trials using both the intravenous and the oral forms. In this review, we present a systematic overview of these trials.     

Clinical implication of coronary tortuosity in patients with coronary artery disease

BackgroundCoronary tortuosity (CT) is a common coronary angiography finding. The exact pathogenesis, clinical implication and long-term prognosis of CT are not fully understood. The purpose of this study is to investigate the clinical characteristics of CT in patients with suspected coronary artery disease(CAD) in a Chinese population.MethodsA total of 1010 consecutive patients underwent coronary angiography with complaints of chest pain or related symptoms were included in the present study (544 male, mean age: 64±11 years). CT was defined by the finding of ≥3 bends (defined as ≥45° change in vessel direction) along main trunk of at least one artery in systole and in diastole. Patients with or without CAD were further divided into CT-positive and CT-negative groups, all patients were followed up for the incidence of major adverse cardiovascular events (MACE) for 2 to 4 years.ResultsThe prevalence of CT was 39.1% in this patient cohort and incidence of CT was significantly higher in female patients than that in male patients (OR = 2.603, 95%CI 1.897, 3.607, P<0.001). CT was positively correlated with essential hypertension (OR = 1.533, 95%CI 1.131, 2.076, P = 0.006) and negatively correlated with CAD (OR = 0.755, 95%CI 0.574, 0.994, P = 0.045). MACE during follow up was similar between CAD patients with or without CT.ConclusionsCT is more often seen in females and positively correlated with hypertension and negatively correlated with coronary atherosclerosis.     

Effect of using nifedipine by patients with chronic congestive heart failure treated with digoxin and furosemide

Nifedipine was administrated to 25 patients with chronic congestive heart failure treated with digoxin and furosemide++, nifedipine (NF) in a daily dose of 30-80 mg for 14 days. Before and after the treatment with nifedipine chest X-ray, blood biochemical investigations, echocardiographic evaluation of the left ventricular function and submaximal exercise test were performed. Nifedipine induced significant decreases in the left ventricular systolic dimension, heart volume, blood serum potassium and uric acid concentrations and hematocrit . Resting and exertional heart rate, blood pressure, exercise power and duration, watt-pulse, myocardial oxygen demand index, ejection fraction, cardiac output, body weight, 24-hour urinary output, blood serum concentrations of urea, creatinine, sodium and chloride changed insignificantly following nifedipine administration. The obtained results suggest that long-term nifedipine treatment of patients who were already given digoxin and furosemide neither improve nor worsen their clinical status.