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Biomedical subjects

P Toutouzas

Publications and source records attributed to P Toutouzas.

At least 19 recordsLinked to original sources
PubMed1999

Thermal heterogeneity within human atherosclerotic coronary arteries detected in vivo: A new method of detection by application of a special thermography catheter.

BACKGROUND: Activated macrophages play an important role in the pathogenesis of acute ischemic syndromes. It has been postulated that detection of heat released by activated inflammatory cells of atherosclerotic plaques may predict plaque rupture and thrombosis. Previous ex vivo studies have shown that there is thermal heterogeneity in human carotid atherosclerotic plaques. METHODS AND RESULTS: To measure the temperature of human arteries in vivo, we developed a catheter-based technique. Ninety patients (45 with normal coronary arteries, 15 with stable angina [SA], 15 with unstable angina [UA], and 15 with acute myocardial infarction [AMI]) were studied. The thermistor of the thermography catheter has a temperature accuracy of 0.05 degrees C, a time constant of 300 ms, and a spatial resolution of 0.5 mm. Temperature was constant within the arteries of the control subjects, whereas most atherosclerotic plaques showed higher temperature compared with healthy vessel wall. Temperature differences between atherosclerotic plaque and healthy vessel wall increased progressively from SA to AMI patients (difference of plaque temperature from background temperature, 0. 106+/-0.110 degrees C in SA, 0.683+/-0.347 degrees C in UA, and 1. 472+/-0.691 degrees C in AMI). Heterogeneity within the plaque was shown in 20%, 40%, and 67% of the patients with SA, UA, and AMI, respectively, whereas no heterogeneity was shown in the control subjects. CONCLUSIONS: Thermal heterogeneity within human atherosclerotic coronary arteries was shown in vivo by use of a special thermography catheter. This heterogeneity is larger in UA and AMI, suggesting that it may be related to the pathogenesis.

Aged↗
PubMed1999

Effects of pacing-induced and balloon coronary occlusion ischemia on left atrial function in patients with coronary artery disease.

OBJECTIVES: The aim of this study was to compare left atrial (LA) function in 16 patients with distal left anterior descending (LAD) and in 16 patients with proximal left circumflex (LCx) coronary artery stenosis at rest and immediately after pacing-induced tachycardia (LAD-pacing [P] and LCx-P) or coronary occlusion (LAD-CO and LCx-CO). BACKGROUND: During left ventricular (LV) ischemia, compensatory augmentation of LA contraction enhances LV filling and performance. The left atrium is supplied predominantly by branches arising from the LCx. Therefore, we hypothesized that one mechanism for the loss of atrial contraction may be ischemic LA dysfunction. METHODS: Left ventricular and LA pressure-area relations were derived from simultaneous double-tip micromanometer pressure recordings and automatic boundary detection echocardiograms. RESULTS: Immediately after pacing or after coronary occlusion, LV end-diastolic pressure, LV relaxation, LA mean pressure and LV stiffness significantly increased in all patients. However, the area of the A loop of the LA pressure-area relation, representing the LA pump function, significantly decreased in groups LCx-P and LCx-CO (from 14+/-3 to 9+/-2, and from 16+/-4 to 9+/-2 mm Hg.cm2, respectively, p < 0.05), whereas it increased in groups LAD-P and LAD-CO (from 12+/-3 to 54+/-10, and from 16+/-3 to 49+/-8 mm Hg.cm2, respectively, p < 0.001). CONCLUSIONS: In patients with LAD stenosis, LV supply or demand ischemia is associated with enhanced LA pump function. However, in patients with proximal LCx stenosis who develop the same type and degree of ischemia, LA branches might have been affected, rendering the LA ischemic and unable to increase its booster pump function.

Angioplasty, Balloon, Coronary↗
PubMed1999

Effect of estrogen on aortic function in postmenopausal women.

We hypothesized that estrogen may alter aortic elastic properties. The aortic pressure-diameter relation was obtained in 20 postmenopausal women, 10 without (group 1) and 10 with (group 2) proven coronary artery disease, before and after intravenous administration of 10 micrograms of 17beta-estradiol. Instantaneous aortic diameter was measured by an intravascular catheter developed in our institution simultaneously with aortic pressure at the same aortic level with a catheter-tipped micromanometer. At baseline, elastic properties of the aorta were decreased in group 2 compared with group 1. Compared with baseline, aortic distensibility was increased in both groups (P < 0.01 and P < 0.05 for groups 1 and 2, respectively) after estrogen administration, whereas the pressure-diameter loop was shifted downward along a different hypothetical line of elasticity, suggesting active changes in the aortic elastic properties. Furthermore, a significant reduction in wave reflection was found in both groups (P < 0.001). This action may contribute to the beneficial effects of estrogen on the cardiovascular system and may have future therapeutic implications in postmenopausal women.

Aged↗
PubMed1998

Aortic elastic properties in Takayasu arteritis.

We describe the case of a female patient with Takayasu arteritis. The aortic elastic properties were improved after the administration of diltiazem, as assessed by the aortic pressure-diameter relation. Consequently, the patient was treated with diltiazem at a dose of 270 mg/day for three years. During this follow-up period, there have been no life-threatening events related to Takayasu arteritis.

Aorta↗
PubMed1998

Left atrial energy in normal subjects, in patients with symptomatic mitral stenosis, and in patients with advanced heart failure.

In a population consisting of 45 subjects (15 patients with mitral stenosis, 15 patients with heart failure, and 15 normal subjects), the left atrial (LA) pressure-area relation was assessed and the correlations between LA stroke work, LA kinetic energy, and LA ejection force were studied. The area of the counterclockwise A loop expressing the LA external work was measured. LA kinetic energy was obtained from the formula: 1/2 x stroke volume x 1.06 x v2, where v = transmitral Doppler A velocity. An excellent correlation was found between LA stroke work index and LA kinetic energy when data from all patients were plotted together (r = 0.95, p <0.001). The Pearson's correlation similarity coefficient between LA ejection force and kinetic energy as well as between LA ejection force and stroke work index was r = 0.54 (p <0.001). The r value of 0.54 was significantly lower than r = 0.95 (p <0.03). LA kinetic energy extends the use of transmitral flow Doppler data to include assessment of LA work. LA work can be obtained noninvasively with a high degree of accuracy.

Atrial Function↗
PubMed1998

Effects of changing the availability of the substrate for nitric oxide synthase by L-arginine administration on coronary vasomotor tone in angina patients with angiographically narrowed and in patients with normal coronary arteries.

We assessed the effects of intracoronary administration of substance P, LNMMA, L-arginine, and nitroglycerin in patients with normal coronary angiograms and in patients with coronary artery disease. LNMMA constricted (p <0.01) and both substance P and nitroglycerin dilated normal and diseased proximal and distal segments and stenoses (p <0.01). L-Arginine reversed the effect of LNMMA in all segments and caused greater dilation of the diseased arteries, including stenoses (p <0.05), indicating that there is a relative deficiency of L-arginine in diseased coronary arteries.

Aged↗
PubMed1998

Unfavorable effects of passive smoking on aortic function in men.

BACKGROUND: The aorta acts as both a conduit and an elastic buffering chamber that modulates left ventricular function and coronary blood flow. Previous studies have shown that active smoking has unfavorable effects on aortic elasticity. OBJECTIVE: To study the association between passive smoking and the elastic properties of the human aorta. DESIGN: Comparison of nonsmokers during passive smoking studies and smokers during active smoking or sham smoking studies. SETTING: Academic medical center. PARTICIPANTS: 16 male nonsmokers were assigned to passive smoking studies, and 32 current, long-term, male smokers were randomly assigned to either active smoking (16 patients) or sham smoking (16 patients) studies. INTERVENTION: All participants underwent diagnostic catheterization. In the passive smoking group, environmental tobacco smoke was vented into an exposure chamber for 5 minutes (mean carbon monoxide level, 30 parts per million). Each participant in the active smoking group smoked one filtered cigarette (1.0 mg of nicotine) under standardized conditions within 5 minutes; each participant in the sham smoking group performed a similar pattern of inhalation with one unlit cigarette. MEASUREMENTS: Aortic elastic properties were studied by measuring the aortic pressure-diameter relation before and for 20 minutes after passive, active, or sham smoking. Instantaneous diameter of the thoracic aorta was measured with a high-fidelity ultrasonic dimension catheter. Instantaneous aortic pressure and diameter were measured at the same site. RESULTS: Both passive and active smoking were associated with changes in the aortic pressure-diameter relation (change in mean distensibility in the passive smoking group, from 2.02 to 1.59 x 10(-6) cm2 x dyne(-1) [for comparisons of time course between passive and sham smoking groups, P < 0.001]; change in mean distensibility in the active smoking group, from 2.08 to 1.51 x 10(-6) cm2 x dyne(-1) [for comparisons of time course between active and sham smoking groups, P < 0.001]). These changes represent decreases of 21% and 27%, respectively. No changes in aortic elasticity were seen in the sham smoking group. CONCLUSIONS: Both passive and active smoking are associated with an acute deterioration in the elastic properties of the aorta. This association between exposure to tobacco smoke and aortic elasticity indicates that aortic function deteriorates during passive or active smoking.

Adult↗
PubMed1998

Relation of von Willebrand factor to occurrence of Q waves and thrombolytic treatment in acute myocardial infarction.

We measured the changes of plasma von Willebrand factor antigen and fibrinogen levels in patients with acute myocardial infarction treated with recombinant tissue plasminogen activator and patients not given fibrinolytic drugs. The von Willebrand factor levels are greater in patients with Q-wave than in patients with non-Q-wave myocardial infarction and are independent of thrombolytic treatment. Fibrinogen levels are depressed by thrombolytic treatment but are unrelated to the presence or absence of Q waves.

Adult↗
PubMed1998

Usefulness of noninvasive detection of left ventricular diastolic abnormalities during isometric stress in hypertrophic cardiomyopathy and in athletes.

We showed previously that the handgrip apexcardiographic test (HAT) is a useful method for detecting left ventricular (LV) diastolic abnormalities in patients with coronary artery disease and systemic hypertension. This study evaluates the use of HAT for assessing the prevalence and types of exercise-induced diastolic abnormalities in patients with obstructive (n = 31) and nonobstructive (n = 35) hypertrophic cardiomyopathy (HC) as well as its potential value for separating healthy subjects and athletes from patients with HC. We obtained a HAT in 66 consecutive patients with HC and in 72 controls (52 healthy volunteers and 20 athletes). A positive HAT was defined by the presence of one of the following: (1) relative A wave to total height (A/H) during or after handgrip > 21% (compliance type), (2) total apexcardiographic relaxation time (TART) > 143 ms or the heart rate corrected TART (TARTI) during handgrip < 0.14, (relaxation type), (3) both types present (mixed type), and (4) diastolic amplitude time index (DATI = TARTI/[A/D]) during handgrip < 0.27. Of the controls, only 1 of 52 healthy subjects and 1 of 20 athletes showed a positive HAT, whereas of the total HC cohort 63 of 66 patients (95%) had a positive result. There was no significant difference in the distribution of these types between obstructive and nonobstructive HC. Further, no LV diastolic abnormalities were present in 10 of 35 patients (29%) with nonobstructive HC at rest and in 3 of 35 patients (9%) during handgrip, whereas of the patients with obstructive HC only 1 of 31 (3%) had no LV diastolic abnormalities at rest and none during handgrip. Based on HAT data, our study demonstrates that in HC (1) LV diastolic abnormalities are very frequent during handgrip; (2) patients with nonobstructive HC show significantly fewer LV diastolic abnormalities at rest than those with obstructive HC; and (3) no significant difference exists between obstructive and nonobstructive HC in the prevalence of types of handgrip-induced LV diastolic abnormalities. Consequently, HAT appears to be of clinical value as an additional tool for separating normal patients and athletes from patients with HC.

Adolescent↗
PubMed1998

Total reconstruction of a diseased saphenous vein graft by means of conventional and autologous tissue-coated stents.

This is the first report of a total reconstruction of a diseased saphenous vein graft, with thrombus-containing lesion and multiple stenoses, by the implantation of arterial graft- and venous graft-coated stents, and of conventional stents. The procedure was successful without any complications, and follow-up angiography after 6 months revealed patency of the vessel.

Angioplasty, Balloon↗
PubMed1998

Early postexercise thallium-201 reinjection after sublingual nitroglycerin augmentation: effects on detection of myocardial ischemia and/or viability.

BACKGROUND: Thallium-201 (201Tl) reinjection after conventional redistribution imaging is a standard procedure, resulting in enhanced 201Tl redistribution which is compatible with viable myocardium. Although this method significantly improves identification of viable myocardium, it increases the investigation time by approximately 1 h. Thus, this technique is suboptimal from the standpoint of patient convenience, since its routine performance may be impractical in a high-volume nuclear medicine laboratory. HYPOTHESIS: This study was undertaken to evaluate the efficacy of an early 201Tl reinjection and imaging protocol in combination with sublingual nitroglycerin, to detect myocardial ischemia and/or viability, and to reduce the need for conventional (4 h) redistribution imaging. MATERIALS AND METHODS: In this study, 62 consecutive coronary patients, referred for the detection of possible myocardial ischemia and/or viability, were involved (mean age 55 years, range 41-70). Of those, 50 had previous angina attacks, with 42 having a history of previous myocardial infarction; 10 patients had coronary artery bypass grafting; and the remaining 2 had atypical chest pain. Immediately after the completion of the initial postexer-cise imaging, 0.3 mg sublingual nitroglycerin followed by the reinjection of 1 m Ci of 201Tl were administered, and two further sets of images were acquired 1 h and 4 h later. RESULTS: In each set of images, a total of 496 segments were analyzed. On postexercise imaging, 305 (61%) segments demonstrated defects of which 198 (65%) showed enhanced thallium uptake, 97 (32%) did not change, and 10 (3%) showed reverse redistribution on 1 h reinjection imaging (IRI). Of the 97 persistent defects, only 17 (6%) showed fill-in of 201Tl on 4 h redistribution imaging (CRI), while 12 (4%) segments showed reverse redistribution. On the other hand, after analyzing the 62 patients of the 1 h IRI, 17 (27%) remained unchanged while in only 1 patient (6%) of 17 the diagnosis changed from myocardial necrosis to ischemia after analysis of the 4 h CRI. CONCLUSION: These results indicate that early postexercise reinjection of 201Tl in combination with sublingual nitroglycerin followed by 1 h image acquisition may prove useful for a comprehensive and convenient assessment of myocardial ischemia and/or viability.

Adult↗
PubMed1998

Effects of postural changes on left atrial function in patients with hypertrophic cardiomyopathy.

BACKGROUND: We assessed left atrial function in normal subjects and in patients with hypertrophic cardiomyopathy (HCM) by using Doppler echocardiography at the supine position and after sudden standing. METHODS AND RESULTS: Twenty-seven patients with hypertrophic obstructive cardiomyopathy (HOCM), 17 patients with HCM, and 35 normal subjects were studied. From the transmitral Doppler flow velocities, peak early and late (E and A) waves, E/A ratio, and time velocity integrals (Ei and Ai) were calculated. Left atrial active contribution (LAAC) was assessed as the ratio Ei/(Ei + Ai). Furthermore, isovolumetric relaxation time (IVRT) was estimated by means of Doppler echocardiography. In the supine position, the E/A ratio was similar in the 3 groups. Conversely, LAAC was significantly higher in patients with HOCM (24.4 +/- 2.0) and in patients with HCM (23.3 +/- 3.3) compared with normal subjects (20.3 +/- 2.3, P <.001 and P <.05, respectively). After sudden standing, LAAC increased significantly in normal subjects by 11%, in patients with HOCM by 24%, and in patients with HCM by 13% (P <.001). Similarly, IVRT increased significantly in all study groups (P <. 001). By using stepwise forward multiple linear regression analysis, we found that LAAC was associated with age, IVRT, and body mass index in the supine position and with diastolic blood pressure and IVRT in the standing position. CONCLUSIONS: Left atrial contribution to left ventricular filling was increased after sudden changes of posture in normal subjects and in patients with HOCM or HCM.

Adult↗
PubMed1998

Exercise capacity in patients with beta-thalassemia major: relation to left ventricular and atrial size and function.

OBJECTIVES: The objective of this study was to examine the association between exercise capacity and echocardiographic indexes of atrial and ventricular function and size in patients with beta-thalassemia major. BACKGROUND: In patients with beta-thalassemia major, the assessment of cardiac function with echocardiography alone does not always correspond to their functional status. Peak oxygen uptake and anaerobic threshold, on the other hand, constitute 2 objective and reproducible determinants of exercise capacity in patients with heart failure. METHODS AND RESULTS: Forty consecutive patients (22 women and 18 men, 18 to 30 years old) who were in stable condition while receiving regular transfusions and 30 age- and sex-matched control subjects were studied. At 2 to 3 days after the last transfusion, each subject underwent complete echocardiographic study followed by cardiopulmonary exercise testing. Left atrial volumes (maximal [Vmax], at onset of atrial systolic [Vp], and minimal [Vmin]) and left ventricular volumes were measured with the biplane area-length method, and left atrial active emptying fraction (ACTEF) and left ventricular ejection (LVEF) fraction were calculated. Peak oxygen uptake (Vo 2 max) and anaerobic threshold (AT) were also estimated. After transfusion, patients with beta-thalassemia major had reduced Vo 2 max and AT and greater left atrial volume in comparison with control subjects. Also, ACTEF and LVEF were significantly lower in the patient group. Moreover, Vo2 max and AT were inversely related to Vmax (r = -0.74 and r = -0.80, respectively) and directly related to ACTEF (r = 0.85 and r = 0.82, respectively) in beta-thalassemia major, whereas they were poorly related to LVEF (r = 0.50 and r = 0. 53, respectively). In the control group, Vo 2 max and AT parameters were related to Vmax and ACTEF in a similar way to that in the beta-thalassemia group. CONCLUSIONS: In patients with beta-thalassemia major, exercise capacity does not correlate with left ventricular dimensions and function. On the contrary, left atrial size and systolic dysfunction are probably predictors of decreased exercise capacity.

Adolescent↗
PubMed1998

Aortic stiffness in young patients with heterozygous familial hypercholesterolemia.

BACKGROUND: Dyslipidemia is a primary risk factor for the development of atherosclerosis. Aortic distensibility is an important determinant of left ventricular function and coronary blood flow whose possible alterations in patients with dyslipidemia have not been fully investigated. METHODS: To assess the effect of dyslipidemia on the elastic properties of the aorta, we studied 60 patients (mean age 37+/-11 years) with heterozygous familial hypercholesterolemia and no manifest arterial disease and compared them with 20 of their normolipidemic siblings (mean age 34+/-10 years). Two indexes of the aortic elastic properties were measured: aortic distensibility was calculated by use of the formula: 2 x (AoS-AoD)/PP x AoD, and aortic stiffness index was calculated by use of the formula: In (SBP/DBP)/(AoS-AoD)/AoD, where AoS and AoD are aortic root end-systolic and end-diastolic diameters, respectively, SBP and DBP are systolic and diastolic arterial pressure, respectively, and PP is pulse pressure. Internal aortic root diameters were measured at 3 cm above the aortic valve by use of two-dimensional guided M-mode transthoracic echocardiography, and arterial pressure was measured simultaneously at the brachial artery by sphygmomanometry. RESULTS: The mean aortic systolic and diastolic diameter index did not differ significantly between the two groups. In contrast, aortic distensibility was found to be significantly reduced in subjects with isolated familial hypercholesterolemia compared with that in the control group (2.15+/-1.72 cm2.dynes(-1).10(-6) vs 3.18+/-1.58 cm2.dynes(-1).10(-6), p < 0.02). In addition, the mean aortic stiffness index was double in patients with familial hypercholesterolemia compared with that in normolipidemic subjects. CONCLUSIONS: Severe dyslipidemia does not overtly influence aortic dimensions but leads to impairment of aortic elastic properties before the occurrence of clinical manifestations of atherosclerotic disease.

Adult↗