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D Georgiou

Publications and source records attributed to D Georgiou.

At least 37 records · Page 2Linked to original sources
PubMed1996

Comparison of electron beam computed tomography scanning and magnetic resonance imaging quantification of right ventricular mass: validation with autopsy weights.

RATIONALE AND OBJECTIVES: We compared, in the same human hearts, the ability of magnetic resonance (MR) imaging and electron beam computed tomography (CT) scanning to accurately quantify the free wall and septal components of right ventricular (RV) mass. METHODS: Eleven hearts extracted at autopsy were subjected to MR imaging and electron beam CT scanning in short-axis projections. Regression analyses of mass determinations obtained by manual planimetry MR imaging and electron beam CT scanning and autopsy weights were performed. RESULTS: RV free wall mass by both MR imaging (53.4 +/- 19.1 g) and electron beam CT scanning (53.9 +/- 20.4 g) correlated well with autopsy weight (57.7 +/- 20.2 g). Regression analysis showed a strong correlation for MR imaging (r = .88, slope = .88, standard error the estimate [SEE] = 7.2 g, p < .001) and electron beam CT scanning (r = .95, slope = .95, SEE = 6.6 g, p < .001). RV septal mass by MR imaging (10.8 +/- 3.5 g) and electron beam CT scanning (7.1 +/- 2.4 g) correlated less well with the autopsy weight (12.5 +/- 6.5 g). Regression analysis showed a fair correlation for MR imaging (r = .45, slope = .83, SEE = 2.05 g, p = .001) and a poor correlation for electron beam CT scanning (r = .46, slope = .17, SEE = 2.25 g, p = .57). CONCLUSION: Both MR imaging and electron beam CT scanning accurately predict RV free wall mass but have difficulty predicting the septal component. Because the septal component constitutes only a small proportion of the total RV mass, determinations of RV mass should be based solely on the free wall component.

Autopsy↗
PubMed1996

Feasibility of ultrafast computed tomography in the early evaluation of coronary bypass patency.

Although ultrafast computed tomography (UFCT) is able to determine coronary artery bypass graft (CABG) patency, the clinical applicability in the early postoperative period has not been investigated. We prospectively studied 22 consecutive patients who developed angina-like chest pain, electrocardiogram (EKG) abnormalities, elevated creatine phosphokinase-MB fractions (CPK-MB fractions) (> 5%), or sudden cardiac death in the early post-CABG period. UFCT (flow mode) examinations from 4 to 28 days postoperatively were performed at six levels with 13 scans each. Indications for obtaining UFCT included chest pain (14), elevated CPK-MB (14), EKG abnormalities (10), and aborted sudden cardiac death (1). There were 78 grafts evaluated with 87 distal anastomoses. Sixty were saphenous vein grafts (SVG), 16 were left internal mammary artery (LIMA) grafts, 1 was a free right internal mammary artery (RIMA), and 1 was a right gastroepiploic artery. The 60 SVG included 9 sequential grafts with 18 distal anastomoses. UFCT identified 5 occluded nonsequential SVG and of these, 3 underwent coronary angiography confirming the UFCT findings. Visualization was inadequate to determine patency in 5/17 internal mammary artery (IMA) grafts, and all 5 were in the early part of this study and felt to be related to UFCT image protocol. All sequential grafts were determined to be patent on UFCT, although visualization was inadequate to determine if one or both of the outflow distal anastomoses were patent. Our series shows early nonsequential SVG occlusion at 5/51 (9.8%) in patients with postoperative clinical signs of possible graft occlusion. UFCT to determine the patency of proximal grafts is feasible in the early postoperative period. If UFCT is indeed a valid test for graft patency, then this study implies that most signs and symptoms of ischemia in the early postoperative period may not represent graft occlusion.

Adult↗
PubMed1995

Racial differences in coronary calcium prevalence among high-risk adults.

A total of 1,461 asymptomatic high-risk adult subjects were studied with digital subtraction fluoroscopy and conventional cinefluoroscopy to detect coronary calcium. Ethnicity and risk factor data were recorded. No subject had a history or electrocardiographic evidence of prior myocardial infarction. The prevalence of coronary calcium by digital subtraction fluoroscopy was high (58%). Substantial ethnic differences in prevalence were noted: 36% of African American subjects, 60% of Caucasian subjects, and 60% of Asian American subjects had definite radiographic evidence of coronary calcium. The difference in prevalence between African American and other subjects was significant (p < 0.0001) by chi-square test for all 3 races. These differences persisted in the unsubtracted cinefluoroscopic images (p < 0.0001) and after controlling for age, gender, and other risk factors (p = 0.003). After 20 +/- 11 months of follow-up, African Americans had more coronary artery disease events (13%) than Caucasians (6%) or Asian Americans (5%) (p = 0.04). Thus, African Americans have a significantly lower prevalence of coronary calcium than do Caucasians or Asian Americans. Based on the follow-up results, these differences in prevalence are not explained by differences in coronary artery disease risk.

Aged↗
PubMed1995

Exercise training improves left ventricular diastolic filling in patients with dilated cardiomyopathy. Clinical and prognostic implications.

BACKGROUND: Patients with dilated cardiomyopathy (DCM) often have left ventricular (LV) diastolic dysfunction that can precede the development of systolic dysfunction. Recent reports showed that exercise training (ET) improves the exercise capacity of these patients. Although this improvement is primarily due to peripheral adaptations, the contribution of LV diastolic filling has not been well defined. The purpose of this study was to determine whether ET can induce changes in LV diastolic filling that can account for an increase in exercise capacity and whether these changes can influence prognosis. METHODS AND RESULTS: We prospectively studied 55 consecutive patients (mean age, 55 +/- 7 years) with DCM. Patients were randomized into a training group (36 patients) or a control untrained group (19 patients) and matched for clinical and functional characteristics. All patients underwent a pulsed Doppler echocardiographic study, a radionuclide angiographic study, and a cardiopulmonary exercise test before and after a 2-month ET program. On the basis of the Doppler LV diastolic filling pattern at the beginning of the study, patients were prospectively divided into three subgroups: A (restrictive pattern), B ("normal" pattern), and C (abnormal relaxation pattern). In the trained group, peak VO2 (+12%; P < .0001), peak workload (+8.5%; P < .005), and lactic acidosis threshold (+12%; P < .0001) were significantly increased after training without changes in LV ejection fraction. However, only subgroup C demonstrated significant improvement in peak VO2 (+15%; P < .005). No changes were observed in the untrained group. In the trained subgroups a significant increase in rapid filling fraction (RFF), peak filling rate (PFR), peak early filling velocity (E), and E/A ratio was noted. A significant decrease in atrial filling fraction (AFF), peak atrial filling velocity (A), deceleration time of early filling velocity (EDT), and isovolumic relaxation time (IVRT) was observed only in subgroup C. No changes were found in untrained subgroups. A good correlation was found between Doppler and radionuclide LV diastolic filling parameters before and after training (P < .0001). Multiple stepwise regression analysis demonstrated that pretraining E/A ratio (P < .0001) and peak heart rate (P < .0002) were positive predictors of pretraining peak VO2. Posttraining increase in exercise tolerance (P < .0001) and increase in E/A ratio (P < .0001) were the strongest predictors of an increase in peak VO2. The independent predictors of cardiac events were a greater RFF and a shorter IVRT and EDT. Stepwise logistic regression showed that Doppler LV diastolic filling patterns are independent predictors of overall cardiac events (P = .02), and restrictive pattern has a worse prognosis compared with B (P = .04) and C (P = .007). However, ET did not reach statistical significance (P = .54) as a predictor of cardiac events. CONCLUSIONS: These data demonstrate that ET induces significant improvement in exercise capacity only in patients with DCM and a pattern of abnormal LV relaxation. The improvement in peak VO2 is significantly correlated with an increase in peak early filling rate and peak filling rate as well as a decrease in atrial filling rate. Doppler echocardiography may be a valuable tool in the prognostic assessment of patients with DCM who will benefit from exercise training.

Blood Flow Velocity↗
PubMed1995

Low intensity exercise training in patients with chronic heart failure.

OBJECTIVES: The present study was designed to evaluate whether a specific program of low intensity exercise training may be sufficient to improve the exercise tolerance of patients with chronic heart failure. BACKGROUND: Recent studies have shown that exercise training can improve exercise tolerance in patients with stable chronic heart failure, mainly through peripheral adaptations. These changes have been observed with exercise regimens at intensities of 70% to 80% of peak oxygen uptake and > 8 weeks. METHODS: We studied 27 patients (23 men, 4 women; mean [+/- SD] age 57 +/- 6 years) with mild chronic heart failure. We classified patients into two groups: trained group and untrained group. The trained group underwent a low intensity (40% of peak oxygen uptake) training program three times/week for 8 weeks. The untrained group performed no exercise. RESULTS: An increase in peak oxygen uptake (17%, p < 0.0001), lactic acidosis threshold (20%, p < 0.0002) and peak work load (21%, p < 0.0002) were obtained in the trained group only. Cardiac output and stroke volume were unchanged. A high correlation was found between the increases in peak oxygen uptake and volume density of mitochondria of vastus lateralis muscle (r = 0.77, p < 0.0002). CONCLUSIONS: Patients with stable chronic heart failure can achieve significant improvement in functional capacity from a low intensity exercise training regimen. The mechanism responsible for this favorable effect involves an increase in mitochondrial density, which reflects an improvement in oxidative capacity of trained skeletal muscles.

Anaerobic Threshold↗
PubMed1995

Right ventricular mass measurement by electron beam computed tomography. Validation with autopsy data.

RATIONALE AND OBJECTIVES: Validation of right ventricular mass quantitation by electron beam computed tomography in humans has not been performed. The ability of electron beam computed tomography to accurately determine the septal component of the right ventricle also has not been determined. This article addresses both issues. METHODS: Twenty human adult hearts obtained at autopsy were scanned by electron beam computed tomography in a short-axis projection. Planimetry of the right ventricular free wall and septal components of each slice was performed and summed to determine right ventricular mass. These measurements were compared against comparable measurements obtained by autopsy weights of the hearts. RESULTS: Right ventricular free wall weights by electron beam computed tomography (53.9 +/- 18.4 g) correlated well (slope = .92, r = .92, standard error of the estimate = 7.4 g, P < .001) with autopsy weights (55.8 +/- 18.4 g). Right ventricular septal weights by electron beam computed tomography (6.1 +/- 2.3 g) correlated poorly (slope = .04, r = .11, standard error of the estimate = 2.4 g, P = .65) with autopsy weights (13.9 +/- 6.3 g). CONCLUSIONS: Electron beam computed tomography quantitation of right ventricular mass is accurate in humans if only the free wall and not the septal component is utilized.

Aged↗
PubMed1995

Myocardial cysticercosis detected by ultrafast CT.

Cysticercosis can affect any organ of the body although central nervous system manifestations are the most common. Cysticercosis involving the myocardium is extremely rare and is usually diagnosed postmortem. We report a case of cysticercosis involving the myocardium diagnosed antemortem using ultrafast CT.

Cardiomyopathies↗
PubMed1995

Near infrared spectroscopy and changes in skeletal muscle oxygenation during incremental exercise in chronic heart failure: a comparison with healthy subjects.

Near infrared spectroscopy (NIRS) is a noninvasive technique of monitoring tissue oxygen saturation by detecting changes in tissue absorbance of two wavelengths (850 and 760 nm) reflecting the relative oxygenation of hemoglobin and myoglobin. Aim of the present study was to determine whether changes in skeletal muscle oxygen saturation during incremental exercise detected by NIRS can reflect an impared oxygen delivery and an early onset of anaerobic metabolism in patients with chronic heart failure (CHF). We studied 19 subjects (mean age 43 +/- 16 years). Seven patients had a history of CHF with a diagnosis of ischemic cardiomyopathy (Group A) and 12 were healthy sedentary (Group B). All patients had a history of dyspnea on exertion (NY-HA II), peripheral edema, pulmonary rales and cardiac gallop sounds over the last 6 months. They were in sinus rhythm and stable clinical condition in the last 3 months. They were well matched regarding age, sex and body surface area. All subjects performed an incremental work rate test in a ramp pattern on a upright cycle ergometer until volitional fatigue. Gas exchange was measured breath by breath with a metabolic chart. Muscle oxygenation was determined, transcutaneously, during the exercise test over the vastus lateralis muscle with NIRS. At peak exercise, work rate, VO2, anaerobic threshold (LAT), heart rate and systolic blood pressure were significantly lower in Group A compared to Group B (92 +/- 28 vs 232 +/- 17 watts; 14 +/- 2 vs 21 +/- 2 ml/kg/min; 868 +/- 225 vs 1317 +/- 354 ml/min; 149 +/- 7 vs 172 +/- 18 b/min; 145 +/- 18 vs 195 +/- 21 mm Hg, respectively; p < 0.0001 for all). In both groups, as work rate increased, tissue oxygenation initially either remained constant near resting levels or decreased. In both groups, muscle oxygenation decreased more steeply near the work rate where lactic acidosis (LAT) was detected. However, patients with CHF had an earlier acceleration in muscle deoxygenation compared to the other group, indicating a premature onset of anaerobic metabolism. Moreover, Group A had a flatter increase in both heart rate and systolic blood pressure and a steeper slope of oxygenation profile at all matched workloads compared to normals (Group A: -0.13 +/- 0.03 ml/min; Group B: -0.06 +/- 0.015 ml/min; p < 0.0001). The LAT correlated with the work rate at which the rate of tissue O2 desaturation accelerated (r = 0.94; p < 0.0001).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1994

Quantitation of in vitro coronary artery calcium using ultrafast computed tomography.

Ultrafast computed tomography (UFCT) has the potential to quantify coronary hydroxyapatite (HAP). However, no definitive studies validating this technique are available. We constructed a human chest phantom model with coronary arteries represented by cylindrical holes containing: (1) calcium chloride solutions, (2) a block of HAP immersed in paraffin (without partial volume effect), and (3) HAP granules embedded in a gelatin matrix (with partial volume effect). We scanned this model to determine the relationship between measured CT number per voxel and density of the calcium per voxel. The relationships between CT number and concentration of calcium chloride was linear (r = 0.992 to 0.999). Using a commercially available standard bone mineral phantom, we were able to estimate the concentration of HAP to an accuracy from 94 to 97% when partial volume effects were absent. However, when partial volume effects were present, two methods of estimating HAP produced significant errors (1 to 384%, and 17 to 52%). We conclude that significant partial voluming errors degrade the accuracy of HAP quantitation and that further evaluation and corrections are needed before such quantitation is clinically applied.

Calcium Chloride↗
PubMed1994

Prevalence of fluoroscopic coronary calcific deposits in high-risk asymptomatic persons.

Coronary calcific deposits are always associated with coronary atherosclerosis. Sensitive radiographic technology can detect coronary calcium before atherosclerosis becomes symptomatic. A total of 1461 asymptomatic high-risk adult subjects were studied with digital subtraction fluoroscopy to detect coronary calcium. Risk factor data were recorded including age, sex, family history, smoking history, diabetes history, body mass index, systolic blood pressure, left ventricular hypertrophy on ECG, total serum cholesterol level, high-density lipoprotein (HDL) cholesterol, and total cholesterol/HDL ratio. Digital subtraction fluoroscopy in the left anterior oblique projection was performed in all subjects. The prevalence of calcific deposits in at least one major coronary artery was high (58.3%). Eleven percent had coronary calcium in all three major arteries. Multivariate logistic regression analysis showed significant correlations (p < 0.05) between the prevalence of coronary calcium and age, smoking history (relative risk = 1.30), diabetes history (relative risk = 1.24), and family history (relative risk = 1.26). In older subjects (at least 65 years of age), smoking and serum lipoproteins assumed greater importance as contributors to coronary calcium, whereas in younger subjects a history of diabetes was more significant. Coronary calcific deposits are prevalent in high-risk asymptomatic subjects. Their occurrence is closely related to most known risk factors.

Age Distribution↗
PubMed1994

Prognostic significance of cardiac cinefluoroscopy for coronary calcific deposits in asymptomatic high risk subjects.

OBJECTIVES: This research investigated the prognostic significance of radiographically detectable coronary calcific deposits. BACKGROUND: Coronary calcific deposits are almost always associated with coronary atherosclerosis. We investigated the association between fluoroscopically determined coronary calcium and coronary heart disease end points at 1 year of follow-up. METHODS: This prospective population-based cohort study was conducted in the suburbs of Los Angeles. Fourteen hundred sixty-one asymptomatic adults with an estimated > or = 10% risk of having a coronary heart disease event within 8 years underwent cardiac cinefluoroscopy for assessment of coronary calcium at initiation of the study. Clinical status including angina, documented myocardial infarction, myocardial revascularization and death from coronary heart disease were determined after 1 year. RESULTS: The prevalence of calcific deposits was high (47%). A follow-up examination at 1 year was successfully completed in 99.9% of subjects. Six subjects (0.4%) had died from coronary heart disease and 9 (0.6%) had had a nonfatal myocardial infarction. Thirty-seven subjects (2.5%) reported angina pectoris, and 13 (0.9%) had undergone myocardial revascularization. Fifty-three subjects had at least one event during the 1-year period. Radiographically detectable calcium was associated with the presence of at least one of these end points, with a risk ratio of 2.7 (confidence limits 1.4, 4.6). The presence of coronary calcium was an independent predictor of at least one end point when controlling for age, gender and risk factors. However, three deaths due to coronary heart disease and two nonfatal myocardial infarctions occurred in subjects without detectable coronary calcium. CONCLUSIONS: The presence of coronary calcific deposits incurs an increased risk of coronary heart disease events in asymptomatic high risk subjects at 1 year. This increased risk is independent of that incurred by standard risk factors.

Aged↗
PubMed1994

Application of ultrafast computed tomography for diagnosis of perivalvular abscesses. Surgical implications.

The presence of a perivalvular abscess is associated with an increased risk of morbidity and mortality with valve replacement and can require extensive debridement and reconstructive procedures. An accurate noninvasive method for preoperative diagnosis may hasten operation and aid in preoperative and surgical management. Two cases are presented in which ultrafast computed tomography accurately identified perivalvular abscesses not detected on two-dimensional transthoracic echocardiography and guided operative intervention.

Abscess↗
PubMed1994

Ultrafast computed tomography for the physiological evaluation of myocardial perfusion.

Quantitation of myocardial blood flow has been sought by the clinician using a variety of imaging modalities and blood indicator dilution techniques. Ultrafast computed tomography has real potential for clinically useful estimations of regional myocardial blood flow. At the present time, there are limitations with this technique and early washout of indicator (iodine) appears to be the most likely explanation for the inaccuracies observed. Several methods have been tried to correct for early washout without success. Preliminary data based on a new algorithm look promising. Currently available techniques for detecting and quantifying myocardial ischemia have significant limitations. A noninvasive method able to determine wide ranges of flow with accuracy will be essential to understand the pathophysiology of ischemia and for directing better methods of managing ischemic heart disease.

Algorithms↗
PubMed1994

Detection of intracardiac masses by ultrafast computed tomography.

Ultrafast computed tomography (CT) is a new imaging technique that relies on electron beam technology. Its short scanning acquisition times eliminate the motion artifacts seen with conventional CT. High temporal and spatial resolution make it ideal for evaluating the heart using only modest amounts of intravenous contrast. Ultrafast CT is extremely valuable for diagnosis and assessment of intracardiac thrombus and cardiac tumors. Although echocardiography is widely used to identify intracardiac thrombus, it sometimes cannot visualize the most common sites, the atria (especially the left atrial appendage) and the cardiac apex. These areas are clearly defined by ultrafast CT. Likewise, the location, size, extent, and tissue density of primary or metastatic cardiac tumors can be characterized using ultrafast CT, which may obviate the need for angiography before operative treatment.

Heart Atria↗
PubMed1993

Ultrafast computed tomography in the diagnosis of diseases of great vessels.

Rapid and accurate detection of great vessel disease is of enormous importance in clinical practice. The search continues for the best technique to evaluate critically ill patients with acute aortic dissection and/or acute pulmonary embolism. Because of its speed and excellent spatial resolution, ultrafast computed tomography (CT) is a very useful tool and may alter the management of patients with aortic disease. Other techniques, such as magnetic resonance imaging (MRI) and transesophageal echocardiography (TEE) are also used in the diagnosis of aortic dissection. Each technique has advantages and pitfalls. At this time it is likely that one technique will complement the other. With further technical improvements, both MRI and ultrafast CT are likely to emerge as the diagnostic tests of choice. In the future, further validation and comparative studies in the acute setting may help to identify the most accurate and useful technique.

Aortic Dissection↗
PubMed1992

Effects of exercise test results on physician perceptions of coronary artery disease probability using a threshold analysis.

The incremental diagnostic value of exercise electrocardiographic testing compared with clinical data alone in the diagnosis of coronary artery disease (CAD) was found to be of limited value in a previous study. That study used a computer algorithm for diagnosing disease. Thus, the strict use of the results apply only to computerized disease diagnosis rather than physicians' diagnoses. The aim of the present study was to determine whether exercise test data improve a physician's ability to detect the presence or absence of CAD and 3-vessel or left main CAD, and whether the data effect the decision to perform angiography. The study sample comprised a data base of 312 patients whose clinical data, exercise test results and coronary anatomy were known. Individual cases were presented to 8 cardiologists with and without exercise data. The cardiologists provided estimates of disease probability and were asked whether they would request coronary angiography. Receiver-operating characteristic curves and goodness-of-fit analysis showed better discrimination and calibration of the estimates for the presence of CAD and 3-vessel/left main CAD after exercise test results were known. Individualized probability thresholds for deciding whether to request angiography were determined for each physician. Forty-three percent of patients crossed greater than or equal to 1 threshold, with 64% of the crossings in the correct direction. For estimating the presence of any CAD, 84% of crossings from below to above a threshold were correct, whereas only 36% from above to below were correct. For 3-vessel/left main CAD, 36% of crossings from below to above a threshold were correct, whereas 88% from above to below were correct.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Angiography↗
PubMed1992

Regression of left ventricular mass in systemic hypertension.

The importance of treatment in systemic hypertension and cardiovascular morbidity and mortality has been established. Although systemic hypertension is the most important factor in the pathogenesis of left ventricular hypertrophy, other factors such as catecholamines and renin-angiotensin system may be involved. Increased left ventricular mass causes reduction in coronary reserve and may lead to acute ischemic events. Equally efficacious antihypertensive agents may have diverse effects on left ventricular hypertrophy and left ventricular function. New tomographic techniques with improved spatial resolution are emerging in the evaluation of left ventricular mass and may therefore provide better assessment of changes in left ventricular mass. With improved measures of left ventricular mass the question as to whether regression of left ventricular mass provides an additional benefit beyond control of blood pressure in hypertensive individuals may be finally answered.

Antihypertensive Agents↗