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Biomedical subjects

R Virmani

Publications and source records attributed to R Virmani.

At least 271 records · Page 15Linked to original sources
PubMed1987

Oxypurinol limits myocardial stunning but does not reduce infarct size after reperfusion.

To explore the role of oxygen free radicals produced by the xanthine oxidase pathway on infarct size and left ventricular function, the effect of oxypurinol, an active metabolite of allopurinol and a potent noncompetitive inhibitor of xanthine oxidase, was assessed in a 90 min, closed-chest, canine preparation of occlusion-reperfusion. Animals were randomized to receive 25 mg/kg iv oxypurinol (n = 13) or saline (n = 13) 60 min after occlusion. Regional myocardial blood flow was measured with radioactive microspheres and regional ventricular function with contrast ventriculography. Hemodynamic variables, regional myocardial blood flow, and size of the occluded bed were similar in the two groups. Oxypurinol failed to reduce infarct size 24 hr after reperfusion when expressed as a percentage of the area at risk (36.3 +/- 4.9% vs 36.0 +/- 5.6%; p = NS). Both groups exhibited comparative radial shortening at baseline and similar degrees of dyskinesia 1 hr into occlusion (-6.6 +/- 1.2% vs -4.9 +/- 1.0%). However, oxypurinol-treated animals demonstrated an improved regional ventricular function at 3 hr after reperfusion (0.7 +/- 2.6% vs -2.8 +/- 2.0%) and a significant improvement at 24 hr (5.4 +/- 2.5% vs -3.2 +/- 1.7%; p less than .05). A reduced neutrophil infiltrate was observed in the border zone in treated animals. These findings suggest that oxygen free radicals derived from the xanthine oxidase pathway contribute to stunning of reversibly damaged myocardium but do not determine the final extent of myocardial necrosis in a canine preparation of reperfusion.

Animals↗
PubMed1987

Reduction of reperfusion injury in the canine preparation by intracoronary adenosine: importance of the endothelium and the no-reflow phenomenon.

We hypothesized that the endogenous coronary vasodilator adenosine may reduce infarct size by progressively increasing reflow in a preparation of coronary occlusion-reperfusion. After 90 min of proximal left anterior descending artery occlusion, 20 dogs were randomized to blood reperfusion with (n = 10) or without (n = 10) adenosine into the proximal left anterior descending vessel at 3.75 mg/min for 60 min after reperfusion. Regional myocardial blood flow was determined serially with microspheres and regional ventricular function was assessed by a computerized radial shortening method. At 24 hr, the area at risk was defined in vivo with monastral blue dye and area of necrosis was determined after incubation of left ventricular slices in triphenyltetrazolium chloride. Hemodynamic variables were similar in the two groups during the experimental protocol. Infarct size was significantly reduced in treated animals, both when expressed as a percentage of the area at risk (9.9 +/- 2.8% vs 40.9 +/- 6.6%, p less than .001) and as a percentage of the left ventricle (4.6 +/- 1.3% vs 18.0 +/- 3.4%, p = .002). This was associated with significant improvement in radial shortening in the ischemic zone 24 hr after reperfusion (10.1 +/- 2.5 vs -2.8 +/- 2.2%, p less than .01). Regional myocardial blood flow was significantly increased in endocardial and epicardial regions from the lateral ischemic zone 1 hr after reperfusion in adenosine-treated animals. Light microscopy demonstrated decreased neutrophil infiltration in the ischemic zone and electron microscopy showed relative preservation of endothelial structure in the subendocardium with reduced neutrophil and red cell stagnation of capillaries in the treated group. These findings suggest that intracoronary administration of adenosine after reperfusion significantly reduces infarct size and improves regional ventricular function in the ischemic zone in the canine preparation.

Adenosine↗
PubMed1987

Coronary artery atherosclerosis revisited in Korean war combat casualties.

To confirm earlier studies of a high prevalence of coronary atherosclerosis in combat casualties of the Korean and Vietnam wars, we examined previously uncut coronary arteries from the hearts of 94 American male combat casualties (mean age, 20.5 years) from the Korean War using computerized planimetry and microscopic evaluation. Six (6.4%) men had severe atherosclerosis (75% to 90% cross-sectional area luminal narrowing) in one or more coronary arteries; five of the six had fibrous plaques, and one had a complicated plaque. Our prevalence is similar to that reported previously (5%). Therefore, to determine whether the decrease in the incidence of severe coronary atherosclerosis today is the result of decreased plaque formation in the young, we will need to examine at least 772 men to detect a 50% decline with 85% to 90% confidence.

Adult↗
PubMed1986

Sudden cardiac death in Air Force recruits. A 20-year review.

We reviewed the clinical and autopsy records of the 19 sudden cardiac deaths that occurred among the 1,606,167 US Air Force healthy, medically screened recruits (90% male; 17 to 28 years old) during a 42-day basic training period between 1965 and 1985. Sixteen (all male) died suddenly of underlying structural heart disease, whereas no anatomic cause of death was identified in the remaining three. Thirty-two nonsudden, noncardiac deaths occurred during the same period, and only two had structural heart disease. Strenuous physical exertion was associated with sudden death in 17 of 19 cases (0.017 deaths per 50,000 exercise-hours), and the most frequent underlying etiology was myocarditis. Sudden cardiac death, a rare event in healthy young adults, is usually associated with exertion.

Adolescent↗
PubMed1986

Total anomalous origin of the coronary arteries from the pulmonary artery.

The clinicopathologic features of four patients with total anomalous origin of the coronary arteries from the pulmonary artery (TCAPA) are presented and compared with 21 previously reported cases. Patients with TCAPA usually present with left ventricular heart failure, angina, or associated cardiovascular anomalies. Of the 19 patients in whom a clinical history was available, 16 were symptomatic before three days of age. All patients died with 60% dying before two weeks of age. Longer survival was associated with additional cardiovascular anomalies that increased pulmonary arterial perfusion pressure, oxygen saturation, or both. Seventeen (68%) patients had additional cardiovascular anomalies, most commonly atrial (nine cases) or ventricular (eight cases) septal defects and tetralogy of Fallot or other variants of pulmonary atresia (four cases). Only five (22%) of 23 had noncardiovascular anomalies. The coronary arteries arose equally from either one ostium or from two, and the number of ostia was not related to either anomalous coronary artery distribution or to the presence of additional cardiovascular anomalies. Cardiomegaly was present in 56% of cases and the majority of patients had myocardial fibrosis or infarction. Embryology is reviewed and evidence is presented to support the theory of involution-persistence of coronary artery anlagen as the pathogenetic mechanism of TCAPA.

Coronary Vessel Anomalies↗
PubMed1986

Effect of Fluosol-DA on infarct morphology and vulnerability to ventricular arrhythmia.

Although the blood substitute perfluorochemical Fluosol-DA has been shown to reduce experimental myocardial infarct size, the electrophysiologic properties of the surviving myocardium have not been assessed. Twenty-six dogs underwent closed-chest occlusion of the proximal left anterior descending coronary artery. Prior to infarction animals were randomly assigned to one of three treatment groups: groups receiving blood exchange with either Fluosol-DA (F = 9) or autologous heparinized blood (H = 8), given 30 minutes following occlusion over the next 30 minutes (these animals were ventilated with 100% oxygen for 6 hours), or a control group (C = 9) receiving no exchange transfusion and ventilated with room air. On the third postmyocardial infarction day the animals underwent programmed stimulation. The area at risk was defined by injecting different colored microvascular dyes into the three coronary beds, and the area of necrosis was defined by sectioning ventricular slices and staining with Mallory's trichrome stain. Infarct size was significantly reduced in the Fluosol-DA-treated group as compared to the heparin-treated and control groups when expressed as a percentage of the area at risk (F = 53.3 +/- 10, H = 67.2 +/- 12.8, C = 73.6 +/- 11.4: F vs H p less than 0.05; F vs C p less than 0.01). Ventricular tachycardia was inducible and sustained in 16 animals (3F, 6H, and 7C), and there was morphologic correlation with greater endocardial necrosis and smaller viable epicardial regions. In the 10 animals (6F, 2H, and 2C) without sustained ventricular tachycardia, there was greater epicardial viability and sparing of the endocardial regions with irregularity of the borders between viable and necrotic myocardium. We conclude that Fluosol-DA not only decreases infarct size but also modifies infarct morphology to reduce electrical instability.

Animals↗
PubMed1986

Electrocardiographic markers of cardiac metastasis.

Cardiac metastases are often clinically inapparent but have important prognostic significance. A total of 1046 consecutive autopsies performed between 1981 and 1983 were reviewed, and 210 patients with both premortem and autopsy diagnoses of cancer were found, in whom a recent (less than 3 months before death) ECG was available. Of these patients, 47 had cardiac metastases (group I) and 163 did not (group II). In group I, 19 patients had new ECG changes suggestive of myocardial ischemia or injury, including either diffuse T wave inversion (10%), segmental (ECG pattern suggestive of a specific coronary distribution) T wave inversion (80%), or ST elevation (10%). None of these patients had symptoms suggestive of myocardial ischemia. In group II, six patients had ECG changes suggestive of myocardial ischemia or injury: four patients with preterminal sepsis, one with myocardial infarction, and one with aspergillus nodules within the myocardium. New atrial arrhythmias (seven patients) and low voltage (10 patients) were found with greater frequency in group I patients (p less than 0.0005 and p less than 0.00001, respectively, vs group II). Patients with normal ECGs were unlikely to have cardiac metastases; however, the finding of nonspecific ST-T wave changes was not helpful in differentiating the two groups. In clinically stable patients with cancer and no cardiac symptoms suggestive of ischemia, any new ECG change should raise the suspicion of cardiac metastases. The ECG finding of myocardial ischemia or injury has high specificity (96%, p less than 0.000001) for cardiac metastases.

Adolescent↗
PubMed1986

Acquired coronary arterial aneurysms: an autopsy study of 52 patients.

In the past decade most studies of coronary arterial aneurysms have been clinical; few have focused on morphology and etiopathogenesis. The subjects of the present autopsy study were 52 patients, 5 months to 80 years of age, with coronary arterial aneurysms. Patients were divided into two groups: 38 with atherosclerotic coronary aneurysms and 14 with aneurysms secondary to inflammation. Of the 38 patients with atherosclerotic aneurysms, 20 (53 per cent) had histories of ischemic heart disease; the aneurysms were in the right coronary artery in 18 (47 per cent), the left coronary artery in 13 (35 per cent), and in the right and left coronary arteries in seven (18 per cent). Of the four major coronary arteries, the average number of severely narrowed arteries (reduction of more than 75 per cent) in cross-sectional luminal area) was 1.8/patient; aortic aneurysms were present in eight of these patients (24 per cent). Of the 14 patients with coronary aneurysms secondary to inflammation, four had histories of ischemic heart disease; 10 had histories of an influenza-like syndrome. Isolated left coronary arterial aneurysms were seen in six of these patients (43 per cent), while eight (51 per cent) had multiple right and left coronary arterial aneurysms. The average number of severely narrowed coronary arteries in this group was 1.5/patient, and only one patient had an aortic aneurysm. Therefore, patients with atherosclerotic aneurysms are more often symptomatic; they have increased heart weights and equal numbers of coronary arterial aneurysms in the right and left vessels, and the majority (89 per cent) have single aneurysms with thrombi in the lumen. Patients with coronary arterial aneurysms secondary to inflammation are younger; the majority of these patients have a prodromal influenza-like syndrome, a low incidence of ischemic heart disease, and multiple coronary arterial aneurysms.

Adolescent↗
PubMed1986

Determinants of left ventricular aneurysm formation after anterior myocardial infarction: a clinical and angiographic study.

To determine factors involved in left ventricular aneurysm formation after transmural anterior myocardial infarction, 79 patients with a first myocardial infarction who underwent cardiac catheterization within 6 months of infarction were evaluated. Patients who had received thrombolytic therapy were excluded. Patients were divided into four groups depending on the status of the left anterior descending artery and the presence or absence of a left ventricular aneurysm: Group I (n = 25): aneurysm with occluded left anterior descending artery; Group II (n = 27): no aneurysm and occluded left anterior descending artery; Group III (n = 23): no aneurysm and patent left anterior descending artery; and Group IV (n = 4): aneurysm with patent left anterior descending artery. Single vessel disease was more common in Group I (aneurysm) compared with Groups II and III (no aneurysm) (chi 2(4) = 12.8; probability value equal to 0.012). Collateral blood supply in the presence of an occluded left anterior descending artery was significantly less in Group I (aneurysm) compared with Group II (no aneurysm) (0.9 versus 2.4, p less than 0.001). The extent of coronary artery disease and collateral blood supply in Groups I and II were directly related (p = 0.012). Neither age, sex nor risk factors for coronary disease correlated with aneurysm formation. At a mean follow-up of 48 months, no differences were observed in the incidence of recurrent angina, new myocardial infarction, embolic events or sudden death. More patients in Group II underwent coronary artery bypass surgery. Total occlusion of the left anterior descending artery in association with inherent poor collateral blood supply is a significant determinant of aneurysm formation after anterior myocardial infarction. Multivessel disease with either good collateral circulation or a patent left anterior descending artery is uncommonly associated with the development of left ventricular aneurysm.

Angiography↗
PubMed1986

A new model to study quantitative effects of laser angioplasty on human atherosclerotic plaque.

A new model for analyzing the major effects of the use of any laser angioplasty system is described. Changes in any of the six major determinants of effect (energy, duration, wavelength, medium, absorption, geometry) can be evaluated. In this report a neodymium: yttrium aluminum garnet (Nd:YAG) laser was used to make 408 laser exposures in vitro on segments of human cadaveric atherosclerotic aorta. Energy, medium (air, human blood, perfluorochemical and saline), geometry and duration were varied. The depth and width of the resultant plaque craters were measured. A large amount of exposure to exposure variability was found in all groups of experiments, even when conditions were held as constant as possible in this rigidly controlled laboratory setting. This variability is attributable to differences in energy absorption by the plaque. Changes in media and fiber optic tip to plaque distance also markedly altered exposure outcome. For example, the average depth of the hole created by a 15 W, 2 second blast with the fiber tip adjacent to the plaque in blood was 1.7 +/- 0.1 mm (n = 27), but the range was between 0.5 and 2.7 mm. Under the same conditions, except with the fiber tip 1 mm away from the plaque, the average hole depth was 0.4 +/- 0.1 mm (n = 12) and the range was 0.0 to 1.7 mm. The use of this model to analyze the major determinants of lasing effects in different laser angioplasty systems should help to select the best conditions for lasing and allow assessment of the variability of outcome.

Aorta, Abdominal↗
PubMed1986

Morphogenesis and clinicopathologic characteristics of recurrent carotid disease.

The histopathologic characteristics of primary plaques and recurrent carotid disease were studied in 32 patients. These data were related to symptoms, recurrence interval (6 to 176 months), arteriographic anatomy, and in situ operative findings. A striking predilection was noted for recurrent lesions to be located in the internal carotid artery near the origin, but still within the confines, of the original endarterectomy site and suture line. Although recurrence was frequently associated with a long primary arteriotomy, evidence of technical faults or periarterial fibrosis was rare. Early recurrent lesions (recurrence interval less than 36 months, n = 13) had significantly more smooth muscle cells and proteoglycans (p less than 0.001) than late recurrent lesions (recurrence interval greater than 36 months, n = 19). As previously reported, features of atherosclerosis (abundant collagen, calcium deposits, and foam cells) were more pronounced in late recurrences (p less than 0.001). However, the histopathologic differentiation between early and late recurrent carotid disease was indistinct. A continuum was noted whereby characteristics of late recurrent lesions increased in proportion to recurrence interval. All recurrent lesions were easily distinguished from primary plaques in that recurrences had a less orderly arrangement of all elements and lacked the classic topographic features of advanced atherosclerosis. An important feature that differentiated primary and recurrent lesions was the presence of surface and intraplaque thrombus in 90% of recurrent lesions (p less than 0.001). In early recurrent disease, luminal surface thrombus was striking; this was frequently platelet-rich and showed organization devoid of neovascularity. Intraplaque thrombus was more common in late recurrent disease, consisted almost entirely of fibrin, and was often contiguous with luminal surface thrombus. No discernible relationships were noted between thrombus associated with recurrent lesions and the presence or absence of symptoms, treatment with antiplatelet agents, and hypertension. This finding suggests that thrombus was a continuous and intrinsic component of recurrent disease rather than a secondary, complicating feature. Recurrent carotid disease is a progressive lesion that stems from ongoing thrombogenesis occurring at the endarterectomy site. Organized thrombus and smooth muscle cell proliferation comprise the bulk of the lesion, which undergoes atherosclerotic change with time.

Aged↗
PubMed1986

Effect of diesel emissions and coal dust inhalation on heart and pulmonary arteries of rats.

Fischer 344 (SPF) rats were exposed by inhalation to respirable particulate levels of 2 mg/m3 diesel emissions, diesel emissions plus coal dust, coal dust, or air for 7 h/d, 5 d/wk for 24 mo. The effects of treatment on body and heart weights, right and left ventricular wall thickness, severity of cardiomyopathy, and changes in the small pulmonary arteries were evaluated after 24 mo of exposure. In all dust-exposed animals, light microscopic examination of the lungs revealed dust-laden macrophages in alveolar spaces and focal accumulations of dust-laden macrophages near the respiratory bronchioles associated with hyperplasia of type II cells. This response was more prominent in animals exposed to diesel emissions alone. Age-related myocardial fibrosis and inflammatory infiltrates were common in all four groups. No statistically significant differences were detected between the groups for heart weights, ventricular wall thickness, and pulmonary arterial wall thickness. However, animals exposed to diesel emissions did show a consistent trend toward increased pulmonary arterial wall thickness, for all size categories of artery, compared to controls.

Animals↗
PubMed1986

Bioprosthetic heart valve rupture associated with trauma.

Disruption of a bovine pericardial bioprosthetic aortic heart valve occurred in a motor vehicle accident, and was treated by valve replacement for progressive aortic insufficiency. Leaflet rupture was through areas of noninflammatory tissue degeneration, corresponding to regions of repeated mechanical stress and trauma that occur during the normal function of tissue valves. Patients with bioprosthetic heart valves may be predisposed to traumatic valve injury. Early diagnosis and replacement of these disrupted valves should be accomplished to avoid sudden, unpredictable heart failure.

Accidents, Traffic↗
PubMed1986

Isolated right ventricular infarction: a rare complication of coronary artery dissection.

Infarction of the right ventricle generally occurs in association with posterior left ventricular infarction, and isolated right ventricular infarction is unusual. We have reported a case of acute infarction of the right ventricle unassociated with infarction of the left ventricle in a patient with type I aortic dissection that extended into the right coronary artery, resulting in near-complete occlusion of its lumen. We believe that poor collateral circulation of the myocardium played a major role in the pathogenesis of isolated right ventricular infarction after sudden occlusion of the right coronary artery.

Aortic Dissection↗
PubMed1986

Visceral larva migrans involving the myocardium: report of two cases and review of literature.

Two cases of asymptomatic visceral larva migrans (VLM) involving the myocardium, discovered during open heart surgery, are reported. Only 7 cases of VLM myocarditis were found in recent English publications. All 7 cases involved children, with most of the patients acutely ill. Our 2 asymptomatic cases, coupled with the high rate of positive serologic tests in the general population, stress the widespread nature of Toxocara canis infection in human and the large number of subclinical, undetected cases.

Child, Preschool↗