Biomedical subjects
Publications and source records attributed to S Stamatelopoulos.
Endothelium-dependent and endothelium-independent dilation were reduced in patients with Raynaud's phenomenon secondary to systemic sclerosis. Conjugated estrogen given for 4 weeks significantly improved endothelial function compared with placebo.
Sixty nondiabetic coronary artery disease (CAD) patients submitted to coronary angiography were asked to rate (score 0 to 20) pain intensity (RPI) during their last major anginal episode having occurred prior to coronary angiography. This parameter was examined in relation to other variables of CAD and to psychological features. Stepwise regression analysis revealed that RPI was not related to New York Heart Association (NYHA) classification of angina or to angiographic variables. Yet, RPI was found to be significantly affected by psychological features: higher RPI scores were reported by low state anxiety patients (P=0.008), by Type A coronary-prone behavior patients (P=0.02) and by patients with high depression (P=0.03).
The effects of acute cigarette smoking on endothelial function were evaluated in the brachial artery of 10 nonsmoking healthy subjects. Endothelial dysfunction observed after cigarette smoking is a phenomenon lasting at least 60 minutes and does not appear to be attenuated with repeat exposure.
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BACKGROUND: Morphologic changes of the vascular endothelium are common in patients with systemic sclerosis and Raynaud's phenomenon. The aim of this study was to evaluate the endothelium-dependent vasodilatation and endothelium-independent vasodilatation and to examine the effects of short-term estrogen administration on vascular responses in these patients. METHODS AND RESULTS: The study included 12 female patients with systemic sclerosis and Raynaud's phenomenon (aged 49+/-14 years) and 12 age- and sex-matched healthy control subjects. With the use of high-resolution ultrasound imaging, brachial artery diameter was measured at rest, during reactive hyperemia (endothelium-dependent response), and after administration of sublingual nitroglycerin (endothelium-independent dilatation). Intima-media thickness of the common carotid artery was also measured. Baseline diameter was similar in patients and control subjects; intima-media thickness was significantly higher in patients (0.83+/-0.3 vs 0.46+/-0.2 mm, P= .002) than in control subjects. Flow-mediated dilatation was reduced in patients (3.6%+/-7% vs 11.9%+/- 4.6%, P = .003); endothelium-independent dilatation also was reduced in patients with Raynaud's phenomenon (14%+/-7% vs 23%+/-6%, P= .003). Vascular responses in 10 patients were examined 15 minutes after administration of conjugated estrogens (25 mg intravenously); there was a significant increase of endothelium-dependent dilatation after estrogen administration (1.7%+/-4% to 6.3%+/-4%, P= .01), whereas endothelium-independent dilatation did not change (13.4%+/-8% to 15.5%+/-7%, not significant). CONCLUSIONS: Endothelium-dependent vasodilatation and endothelium-independent vasodilatation are impaired in patients with Raynaud's phenomenon secondary to systemic sclerosis, whereas intima-media thickness is increased. Short-term estrogen administration can improve endothelial dysfunction in this group of patients.
The diagnostic value of antimyosin scanning in 7 patients with biopsy-proven cardiac amyloidosis was examined in this study. Antimyosin imaging was positive in all amyloid patients, with more intense uptake in patients with heart failure.
The effect of short-term smoking on endothelium-dependent and endothelium-independent dilatation of the brachial artery was tested in 27 healthy volunteers using high-resolution ultrasound imaging. Short-term smoking led to a significant decrease in endothelium-dependent dilatation.
OBJECTIVE: Previous studies have shown that endothelial dysfunction, an early sign of atherosclerosis, occurs in animal models of diabetes mellitus and in resistance vessels of patients with insulin-dependent diabetes. In the present study we examined whether young patients with insulin-dependent diabetes without microalbuminuria present abnormal endothelial function of large peripheral arteries. METHODS: Twenty-six patients with insulin-dependent diabetes without microalbuminuria were compared with 26 normal controls and 5 patients with insulin-dependent diabetes with microalbuminuria. Brachial artery diameter was measured at rest, during reactive hyperaemic flow (endothelium-dependent dilatation) and after sublingual isosorbide dinitrate (endothelium-independent dilatation). RESULTS: Baseline artery diameter and flow as well as the degree of reactive hyperaemia were similar in all groups compared to controls. Flow-mediated dilatation was lower in patients with diabetes without microalbuminuria (5.8 +/- 7 vs 11 +/- 7%. P = 0.01) as well as in patients with diabetes without microalbuminuria (0.75 +/- 2.5 vs 11 +/- 7%, P = 0.003); nitrate-induced dilatation was normal in patients without microalbuminuria and attenuated in patients with microalbuminuria. In the group of diabetes patients without microalbuminuria, those with disease duration > 10 years and HbAlc > 6% had the worse endothelial function. CONCLUSIONS: Our results demonstrate that endothelial dysfunction of conduit arteries can be detected in patients with insulin-dependent diabetes mellitus without microalbuminuria, probably contributing to the high prevalence of atherosclerosis in these patients.
This work examines whether the 24 h blood pressure (BP) pattern per se might affect the left ventricular structure independently of the pressure level. One hundred subjects with abnormally high office BP readings who had never received any antihypertensive treatment were submitted to 24 h ambulatory BP monitoring and left ventricular echocardiographic assessment. They were classified into two groups, as follows: dippers (group 1), consisting of 46 subjects whose mean nighttime systolic BP was reduced by at least 10% in comparison to the corresponding daytime value, and nondippers (group 2), consisting of 54 subjects whose nighttime BP did not drop or was reduced by < 10%. Left ventricular mass and end-diastolic volume values, both normalized for body surface area, were significantly higher in nondippers (r = 3.12, P < .003, and r = 7.46, P < .001, respectively). The two groups did not differ in diastolic thickness of either intraventricular septum or left ventricular posterior wall (both values normalized for body surface area), in mean 24 h systolic or diastolic or average blood pressure, or in age. In conclusion, in untreated essential hypertension diagnosed on the basis of abnormal office BP readings, the higher incidence of left ventricular mass increase in subjects unable to reduce their blood pressure during the night was more due to left ventricular dilatation than to myocardial wall thickening. The effect of the 24 h BP profile on left ventricular volume appears to be independent of both the BP level and age.
To compare the effect of four drug groups on the ambulatory circadian blood pressure (BP) pattern, amiloride hydrochlorothiazide, atenolol, nifedipine, and perindopril (5/50 mg/d, 100 mg/d, 40 mg/d, and 4 mg/d respectively, for 14 days) were alternated in each of 20 essential hypertension patients. Diuretics induced the largest (P < 0.05) drop in mean 24-hour systolic BP (-12 mmHg, P < 0.001). Atenolol reduced only its standard deviation, and nifedipine reduced only the mean daytime systolic BP (P < 0.05). The mean 24-hour diastolic BP was equally reduced by all drugs except nifedipine, which only reduced (P < 0.05) the mean daytime value. The mean 24-hour heart rate was decreased by atenolol (P < 0.001), increased by diuretics (P < 0.05), and unchanged with perindopril, while nifedipine increased (P < 0.05) only its night-time value. In conclusion, diuretics were the strongest agents in reducing systolic BP, atenolol the only agent that reduced variability, perindopril the only agent that did not affect the heart rate, and nifedipine reduced only daytime BP values.
Patients with hypothyroidism are considered to have an increased risk of developing atherosclerosis; because endothelial dysfunction is an early sign of atherosclerosis, we investigated whether endothelial dysfunction is present in patients with hypothyroidism. Thirty-five subjects with various TSH levels were investigated by high-resolution ultrasound imaging of the brachial artery to assess endothelial and smooth muscle responses. Flow-mediated, endothelium-dependent vasodilatation was significantly higher in subjects with TSH 0.4-2 microIU/mL (11.8 +/- 2.7%), compared with subjects with TSH 2.01-4 microIU/mL (6.8 +/- 2.9%), 4.01-10 microIU/mL (5.2 +/- 6.3%) and >10 microIU/mL (4.0 +/- 4.4%); TSH levels correlated inversely to endothelium-dependent dilatation. Thus, flow-mediated vasodilatation, a marker of endothelial function, is impaired not only in patients with mild hypothyroidism but also in subjects with "high-normal" serum TSH levels (ie, 2.01-4.0 microIU/mL) that may be characterized as possibly abnormal.
Invasive and non-invasive methods exist to assess left ventricular compliance (LVC). This work has two parts, one experimental and one clinical. We estimated left chamber stiffness in dogs by using volume data from radionuclide ventriculography (RNV) and left ventricular pressure data, synchronized with a gating system to the intraventricular dp/dt max to obtain volume and pressure data from a mean cardiac cycle. In five dogs after acute experimental ischaemia, the modulus chamber stiffness Kp rose from 30.2 +/- 4.4 to 55.4 +/- 5.9 (P < 0.01). In 10 dogs with experimental infarction after intra-aortic balloon pumping, Kp decreased from 33.7 +/- 5.0 to 15.5 +/- 3.9 (P < 0.01) and in five dogs with experimental infarction, after intravenous infusion of sodium nitroprusside, Kp decreased from 41.4 +/- 5.5 to 22.2 +/- 2.8 (P < 0.01). In eight normal volunteers and in 20 postmyocardial infarction patients, we estimated a parameter reflecting the LVC by using volume data with blood flow velocity at the mitral valve annulus. Assuming that the mitral flow-velocity variation reflects LV pressure changes, the formula LVC = (dv/dt)/(dp-dt) becomes (dv/dt)/(df/dt) = dv/df. Values obtained in normals were 0.841 +/- 0.295 m-1s and after myocardial infarction 0.331 +/- 0.10 m-1s. Both methods allow clear separation in groups of animals or patients according to the expected changes in LVC or stiffness.
This experimental study compares the effect of catecholamine infusion to the effect of intraaortic counterpulsation (IABP) while initiating intraventricular balloon pumping (IVBP) in the fibrillating heart. In 12 dogs IVBP started immediately after the induction of ventricular fibrillation. Intravenous adrenaline or noradrenaline (at a progressively increasing infusion rate until the systolic aortic blood pressure was 120 mm Hg) was interchanged with IABP. The systolic aortic pressure, the aortic flow and the mean left atrial pressure were, respectively, 120.4 +/- 0.5 mm Hg, 42 +/- 4 ml kg-1 min-1 and 18.7 +/- 1.2 mm Hg (x +/- SEM) ten min after initiating catecholamine infusion and 97 +/- 5 mm Hg (with a 131 +/- 4 mm Hg diastolic wave), 69.6 +/- 4 ml kg-1 min-1 and 16 +/- 1.5 mm Hg ten min after initiating IABP. The difference in aortic flow was significant (p < 0.001). The results indicate that a better aortic flow may be obtained by combining IVBP and IABP than IVBP and vasoconstrictive agents in the fibrillating heart. If IVBP, IABP and catecholamines are combined, both AF and AP may increase.
This study examined whether or not the electrophysiological effect of amiodarone on the heart is mediated through its action on thyroxine metabolism. Serum thyroid hormones and ECG were evaluated before and serially during amiodarone (15 subjects) and benziodarone (15 subjects) administration. Both amiodarone and benziodarone shifted the peripheral conversion of thyroxine (P less than 0.001 for amiodarone and P less than 0.001 for benziodarone) towards reverse triiodothyronine and away from triiodothyronine, whilst TSH levels initially fell and then rose with both drugs. After amiodarone the heart rate decreased (P less than 0.025), whilst the PR (P less than 0.005) and the QT interval (P less than 0.005) corrected for the heart rate increased. By contrast with benziodarone only the PR interval decreased (P less than 0.05). Since both drugs had roughly similar effects on thyroid hormone metabolism but different ones on the ECG, our results provide indirect evidence against the hypothesis that the antiarrhythmic effects of amiodarone are mediated through a decrease in the serum T3 presented to the peripheral tissues.
This study investigates whether the degree of hypertension may be evaluated by information derived from the 24-h blood pressure (BP) curve unrelated to the pressure height. We performed 24-h BP intra-arterial monitoring in 52 bed-confined subjects (10 normotensives, 10 borderlines, and 32 hypertensives on WHO criteria). Computer analysis of 1152 BP values per subject per 24-h revealed the following: During the night hours, the percentage of the 1152 systolic BP values greater than or equal to 160 (in mmHg) increased (or did not change if 100%) in all subjects with mean 24-h systolic BP (24-h BP) greater than 170 and it decreased (or did not change if 0%) in all subjects with 24-h BP less than 150. The change in the percentage of the 1152 diastolic BP values greater than or equal to 95 during the night hours did not correlate to either the mean 24-h diastolic or systolic BP. The higher the mean 24-h systolic BP, the lower the skewness of the distribution of the 1152 systolic BP values (p less than 0.01). No such correlation existed between the skewness of the distribution of the 1152 diastolic BP values and either the mean 24-h diastolic or systolic BP. It is concluded that both the change in systolic BP during the night hours and the skewness of its distribution during the 24-h monitoring period are correlated to the severity of hypertension.
The efficacy of intraaortic counterpulsation (IABP) in severe cardiogenic shock after acute myocardial infarction is questioned because of the lack of a large controlled series. Out of 52 patients treated for severe, prolonged cardiogenic shock 3 improved with 'conventional' treatment. Forty-nine patients did not improve and were in 'intractable' shock for an average of 10.74 +/- 7.14 h (means +/- SD). Of these, 34 were treated with IABP. Ten survived longer than a month. Of the remaining 15 patients of similar age, severity and duration of shock, in whom the balloon could not be made to operate, none survived. It is suggested that intraaortic counterpulsation can save a number of patients with severe protracted cardiogenic shock after all other available treatment modalities have failed.
Intra-observer variability for history and simple test evaluation was assessed in a group of 10 final-year medical students and in five senior hospital staff members. Substantial agreement between the results of two evaluations made 7-10 days apart was found in 20 out of 30 instances for staff and in 17 out of 60 instances for students. However, there were instances when variability seemed to be unrelated to the academic standard of students or to the training and experience of staff. It is concluded that the nature of diagnostic procedure and present training in medical school or long-term experience may not be the only factors that affect intra-observer variability in everyday simple diagnostic applications.
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