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Biomedical subjects

V G Davila-Roman

Publications and source records attributed to V G Davila-Roman.

9 recordsLinked to original sources
PubMed1999

Noninvasive coronary artery imaging in the diagnosis and management of patients with ischemic heart disease.

The inherent limitations of x-ray coronary angiography have led to the development for both noninvasive and minimally invasive techniques for imaging the coronary arteries to assist in the diagnosis and management of patients with ischemic heart disease. Significant advances in transesophageal echocardiography, electron beam computed tomography, and magnetic resonance imaging now permit imaging of the proximal to mid-coronary arteries. Moreover, results of initial studies demonstrate the promise of these methods to detect coronary artery stenoses. In addition, each of these methods provides biochemical or physiologic data about the stenoses that are not obtainable through x-ray angiography. Quantification of coronary calcification via electron beam computed tomography has shown promise as a surrogate marker of coronary atherosclerosis. Transesophageal echocardiography and magnetic resonance imaging appear useful in evaluating the physiologic significance of angiographically detectable coronary artery stenoses via assessment of coronary blood flow. However, it should be noted that significant improvements in technology or acquisition parameters must occur before these techniques can be used on a routine clinical basis for coronary artery imaging. The relative merits and ultimate clinical potential of each of these techniques are discussed in this article.

Calcinosis↗
PubMed1997

Prolonged exercise decreases serum leptin concentrations.

Serum leptin and free fatty acid concentrations were determined in two groups of subjects undergoing strenuous exercise: 12 men who fasted overnight and then pedaled a stationary ergometer for 2 hours, and 14 nonfasting ultramarathon runners. Blood samples were collected before exercise, immediately after cessation of exercise, and 6 to 24 hours after the end of the exercise period. Two hours of strenuous pedaling following an overnight fast significantly reduced mean leptin levels by 8.3%; free fatty acids were highly increased and correlated well with the decrease in serum leptin (r = .737, P = .01). After 6 hours of rest and refeeding, leptin concentrations recovered to preexercise levels and free fatty acid concentrations were decreased to less than preexercise levels. A similar decrease in serum leptin levels (12.3%) occurred in subjects who fasted overnight and then for a period corresponding to the cycle exercise period. The prolonged exercise of an ultramarathon significantly reduced leptin concentrations by 32% in comparison to prerace levels; free fatty acid concentrations were highly increased, but did not correlate with the change in serum leptin concentrations (r = .366, P = .20). Leptin and free fatty acid concentrations all trended toward prerace levels in blood samples collected 18 to 24 hours after cessation of racing. The results suggest that the negative energy balance of exercise can reduce serum leptin concentrations, but that the significant decrease occurs only at extremes of severity/duration of the exercise-induced negative balance. The possible physiological role of reduced leptin concentrations in response to energy balance and the role of free fatty acids in mediating the response are discussed.

Adult↗
PubMed1995

A randomized comparison of intravenous amrinone versus dobutamine in older patients with decompensated congestive heart failure.

OBJECTIVE: To compare the hemodynamic effects of amrinone and dobutamine in patients 75 years of age or older who have severe congestive heart failure requiring invasive hemodynamic monitoring and inotropic support. DESIGN: Prospective, randomized, double-blind clinical trial. SETTING: Coronary care unit of a university teaching hospital. PARTICIPANTS: Fourteen patients > or = 75 years of age (mean 80.3 +/- 5.7 years) with refractory New York Heart Association class IV congestive heart failure. All patients had a cardiac index < 2.5 L/min/M2 (mean 1.8 +/- 0.3 L/min/M2), pulmonary capillary wedge pressure > or = 18 mm Hg (mean 26 +/- 10 mm Hg), and left ventricular ejection fraction < 40% (mean 26 +/- 10%). INTERVENTION: Patients were randomly assigned to treatment with 2-hour infusions of amrinone (n = 7) or dobutamine (n = 7) at fixed dosages of 5 and 10 micrograms/kg/min. MEASUREMENTS: Complete hemodynamic data were obtained at baseline and after each 2-hour medication infusion. Transthoracic two-dimensional echocardiography was performed at baseline and after the 10 micrograms/kg/min medication dose. The primary analysis compared the effects of the two drugs on cardiac index and stroke volume index at each of the two dosages. RESULTS: Both amrinone and dobutamine had salutary hemodynamic effects, as indicated by improvements in cardiac index, stroke volume index, pulmonary capillary wedge pressure, and systemic vascular resistance (all P < .05 except effect of amrinone on stroke index and wedge pressure). Although the overall hemodynamic effects of amrinone and dobutamine were similar, stroke volume index was higher with dobutamine at the 10 micrograms/kg/min dose (35 +/- 7 ml/M2 vs 26 +/- 6 mL/M2; P = .045). Two dobutamine patients were withdrawn from the study after the 5 micrograms/kg/min dose due to adverse effects (tachycardia, increased ventricular ectopy). One additional patient in each group was noted to have ventricular arrhythmias not requiring termination of the protocol. CONCLUSIONS: Both amrinone and dobutamine are efficacious in improving hemodynamics in older patients with severe congestive heart failure caused by left ventricular contractile dysfunction. Despite the effect of aging on beta-adrenergic responsiveness, dobutamine is at least as effective as amrinone but may be associated with a higher incidence of arrhythmic side effects.

Aged↗
PubMed1995

Multiplane transesophageal echocardiographic doppler imaging accurately determines cardiac output measurements in critically ill patients.

OBJECTIVES: To compare cardiac output and stroke volume measured by multiplane transesophageal Doppler echocardiography with that measured by the thermodilution technique. DESIGN: Prospective direct comparison of paired measurements by both techniques in each patient. SETTING: Cardiac surgery and myocardial infarction intensive care units. PATIENTS: Twenty-nine patients, mean age (+/- SD) 67 +/- 8 years. Nineteen had undergone open heart surgery and 10 had suffered acute myocardial infarction. METHODS: Cardiac output and stroke volume were measured simultaneously by the thermodilution technique and multiplane transesophageal Doppler echocardiography via the transgastric view (119 +/- 8 degrees) with the sample volume positioned at the level of the left ventricular outflow tract. RESULTS: Stroke volume and cardiac output measurements were obtained in 29 of 33 patients (88%). Mean values were 50 +/- 13 mL and 4.8 +/- 1.3 L/min by Doppler and 51 +/- 14 mL and 4.9 +/- 1.4 L/min by thermodilution (r = 0.90, r = 0.91, p < 0.001). The mean differences in values obtained with the two techniques were 1 +/- 6 mL (2 +/- 12%) and 0.1 +/- 0.7 L/min (2 +/- 12%). CONCLUSIONS: Multiplane transesophageal echocardiography enhances the ability to estimate accurately cardiac output and stroke volume by providing new access to left ventricular outflow tract in critically ill patients.

Aged↗
PubMed1993

Strategy for the reduction of stroke incidence in cardiac surgical patients.

Atherosclerosis of the ascending aorta (AAA) and severe carotid artery disease are risk factors for stroke in cardiac surgical patients. Twelve hundred of a consecutive series of 1,334 patients 50 years of age or older having a cardiac operation were screened for the presence of AAA by intraoperative ultrasonographic scanning and for the presence of carotid artery occlusive disease (791 of 798 patients > or = 65 years of age and younger symptomatic patients) by carotid duplex scanning. Coronary artery disease was present in 88% of the patients. Patients with moderate or severe AAA (n = 231; 19.3% of the total) were treated by ascending aortic replacement (n = 27) or by modified, less extensive techniques (n = 168) to avoid the atherosclerotic areas. Thirty-three patients had combined carotid endarterectomy and cardiac operation. Thirty-day mortality and stroke rates for the 1,200 patients were 4.0% and 1.6%, respectively. The stroke rate was low (1.1%) among the 969 patients with no or mild AAA. It was zero among 27 patients with moderate or severe AAA who had ascending aortic replacement and among the 33 patients who had carotid endarterectomy. The stroke rates were higher for 111 patients with moderate or severe ascending aortic disease who had only minor interventions (6.3%) and for 16 patients with severe carotid artery disease who did not have carotid endarterectomy (18.7%). Screening for AAA and carotid artery disease and aggressive surgical treatment of moderate or severe AAA and severe or symptomatic carotid artery disease appears to reduce the frequency of stroke in older cardiac surgical patients.

Aged↗
PubMed1992

Management of the severely atherosclerotic ascending aorta during cardiac operations. A strategy for detection and treatment.

Embolization of atheroma from the ascending aorta is a principal cause of stroke after cardiac operations. We have previously shown that intraoperative ultrasonographic scanning of the aorta rapidly, safely, and accurately identifies atheromatous disease in the ascending aorta. Intraoperative ultrasonography of the ascending aorta was performed in 500 of a consecutive series of 540 patients 50 years of age or older (mean 68 years) who underwent a variety of cardiac operations. Eighty-nine percent required bypass grafting. Sixty-eight patients (13.6% of the total) with a mean age of 72 years (range 55 to 85 years) had significant atheromatous disease in the ascending aorta and were considered to be at increased risk for embolization. Palpation identified the atheromatous disease in only 26 (38%) of these patients and underestimated its severity. A total of 168 modifications in the standard techniques for cannulation and clamping of the aorta were implemented in the 68 patients (mean 2.5 per patient) and included alterations in the sites of aortic cannulation (50 patients), aortic clamping (54 patients), attachment of the vein grafts (35 patients), and cannulation for infusion of cardioplegic solution (29 patients). Ten patients with severe diffuse atheromatous disease underwent graft replacement of the ascending aorta with hypothermic circulatory arrest without aortic clamping. Fourteen patients with symptoms or with high-grade carotid artery occlusive disease were treated by concomitant carotid endarterectomy. Thirty-day mortality for the entire group was 3.4% (17 patients). Permanent neurologic deficits occurred in five (1.0%) of the patients in the entire group but in none of the 68 patients with significant atheromatous disease in whom modifications in technique were used. One patient in the latter group had a reversible ischemic neurologic deficit. Modification of standard cannulation and clamping techniques based on ultrasonography may reduce the frequency of stroke related to atheromatous embolization.

Aged↗
PubMed1991

Intraoperative ultrasonographic evaluation of the ascending aorta in 100 consecutive patients undergoing cardiac surgery.

Dislodgement of atheromatous plaque from the ascending aorta following manipulation is one of the principal causes of stroke following cardiac surgery. To define clinical correlates that predict the presence of severe atherosclerosis, we performed ultrasonographic evaluation of the ascending aorta at the time of cardiac surgery in 100 consecutive patients. The ascending aorta was divided into three equal segments for analysis, and the severity of atherosclerosis was determined as mild when intimal thickening (less than 3 mm) was localized to one segment, moderate when intimal thickening (greater than 3 mm) was present in one or two segments, and severe when intimal thickening (greater than 3 mm) was present throughout the entire circumference in all three segments. Thirty-eight percent of the studies were normal, mild atherosclerosis was present in 33%, moderate atherosclerosis in 19%, and severe atherosclerosis in 10% of the patients. Palpation of the ascending aorta to detect atherosclerosis significantly underestimated the presence (p less than 0.001) and severity (p less than 0.001) of atherosclerosis when compared with ultrasonography. Age, carotid artery disease, diabetes, gender, smoking, and hypertension were evaluated for their ability to discriminate between normal and severely atherosclerotic aortas. Stepwise logistic regression analysis showed age (p less than 0.02) and diabetes (p less than 0.04) to be significant independent predictors of the presence of severe atherosclerosis in the ascending aorta. Based on the ultrasonographic findings, the operative procedure was altered to reduce the risk of embolization in 17% of the patients. We conclude that high-resolution images of the ascending aorta for identification of atherosclerosis can be obtained by ultrasonography.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗