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Biomedical subjects

D Vitale

Publications and source records attributed to D Vitale.

At least 37 records · Page 2Linked to original sources
PubMed1985

Effect of verapamil on pH of ischemic canine myocardium.

Verapamil has been shown to depress the contractility of ischemic myocardium. The present study was designed to determine whether that effect is due to an increase in ischemic injury caused by the drug or whether it might reflect a protective effect. A critical partial occlusion was effected on the left anterior descending coronary artery of 16 open chest foxhounds. A fiberoptic pH probe was implanted in the subendocardium of the ischemic zone, and coronary blood flow was reduced by 79% from a control value of 38 +/- 4 ml/min and held constant. Mean coronary perfusion pressure was decreased 48% from its control value of 90 +/- 6 mm Hg and remained constant. Eight animals were treated with intravenous verapamil, beginning 20 to 30 minutes after the onset of ischemia, in incremental doses (5, 10 and 20 micrograms/kg per min) and eight were treated with placebo. The pH of the ischemic zone increased after institution of treatment in the verapamil group (+ 0.04 +/- 0.05 pH unit) whereas it decreased in the placebo group (- 0.06 +/- 0.4 pH unit) during the first dose (p less than 0.05). Although the difference in pH between the two groups was marked at all doses (p less than 0.03) compared with control partial occlusion, verapamil caused no significant change in heart rate (+ 0.1 +/- 1 beat/min in the verapamil group versus + 0.6 +/- 4.5 beats/min in the placebo group), mean arterial pressure (- 7.5 +/- 4 versus - 4.3 +/- 3 mm Hg, respectively) or cardiac output (- 0.2 +/- 0.07 versus - 0.02 +/- 0.04 liters/min, respectively) comparing control with the first or the second dose of verapamil.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Quantitative and qualitative analysis of the relationship between exercise-induced R wave amplitude changes and severity of coronary artery disease.

The correlation between R wave voltage variations (delta R) and the angiographic severity of coronary artery disease (CAD) at progressively increasing heart rate (HR) steps was evaluated in 51 patients (pts) without CAD (OV), in 42 pts with single (SVD), in 43 with double (DVD) and in 59 pts with triple vessel disease (TVD). At the end of stress the sensitivity of delta R was higher in DVD and TVD pts than in SVD pts. There was no clear correlation between exercise-induced R wave changes and the angiographic severity of CAD, since the qualitative and quantitative delta R evaluation during effort showed similar changes in delta R for a wide range of HR's in the entire study population. Since different degrees of exercise tolerance were found in pts with SVD, DVD and TVD, we hypothesize that the correlation between delta R and the severity of CAD at the end of stress testing may be artifactual.

Analysis of Variance↗
PubMed1983

Optimum fourier filtering of cardiac data: a minimum-error method: concise communication.

Random fluctuations limit the accuracy of quantities derived from cardiac time-activity curves (TACs). To overcome this problem, TACs are often fitted with a truncated Fourier series giving rise to two sources of error: (a) the truncated series may not adequately describe the TAC shape, causing errors in parameters calculated from the fit: and (b) successive TACs acquired from the same subject under identical circumstances will fluctuate due to limited counts, causing the Fourier fits (and parameters derived from them) to fluctuate. These two errors, respectively, decrease and increase as the number of harmonics increases, suggesting the existence of a minimum in total error. This number of harmonics for minimum error (NHME) was calculated for each of six common parameters used to describe LV TACs. The "true" value of each parameter was determined from TACs of very high statistical precision. Poisson noise was added to simulate lower count rates. For low-count TACs, use of either a smaller or a larger number of harmonics resulted in significantly greater error. NHME was found to occur at two harmonics for the systolic parameters studied, regardless of the noise level present in the TAC. For diastolic parameters, however, NHME was a strong function of the noise present in the TAC, varying from three harmonics for noise levels typical of regional TACs, to five or six harmonics for high-count global TACs.

Diastole↗
PubMed1981

The glucoregulatory response to intravenous glucose infusion in normal man: roles of insulin and glucose.

In order to differentiate the roles of hyperinsulinemia and hyperglycemia per se in the homeostatic response to i.v. glucose administration, two groups of normal subjects were given either glucose alone (3.5 mg kg-1 min-1) or glucose (3 mg kg-1 min-1) in conjunction with somatostatin (500 microgram hr-1), insulin (0.15 mU kg-1 min-1) and glucagon (1 ng kg-1 min-1). Glucose kinetics were measured by the primed-constant infusion of 3-3H-glucose. During the infusion of glucose alone, plasma glucose stabilized at levels 45--50 mg/dl above the fasting values. Endogenous glucose output was markedly suppressed by 85%--90% while glucose uptake rose to values very close to the infusion rate of exogenous glucose. Glucose clearance remained unchanged. Plasma insulin rose to three-fourfold while plasma glucagon fell by 25%--30%. When glucose was infused with somatostatin, insulin, and glucagon, plasma insulin was maintained at levels 50% above baseline while glucagon remained at preinfusion levels. Under these conditions, the infusion of exogenous glucose resulted in a progressive increase of plasma glucose which did not stabilize until the end of the study period (190 mg/dl at 120 min). Endogenous glucose production was consistently suppressed (52%) but significantly less than observed with the infusion of glucose alone (p less than 0.01). Glucose uptake increased to the same extent as with glucose alone, despite the more pronounced hyperglycemia. Thus, glucose clearance fell significantly below baseline (25%--30%; p less than 0.01). These data demonstrate that hyperglycemia per se (fixed, near basal levels of insulin and glucagon) certainly contributes to the glucoregulatory response to i.v. glucose administration by both inhibiting endogenous glucose output and increasing tissue glucose uptake. However, the extra-insulin evoked by hyperglycemia is necessary for the glucoregulatory system to respond to the glucose load with maximal effectiveness.

Adult↗
PubMed1980

Evaluation by multivariate analysis of changes in systolic time intervals during exercise in the supine and upright positions.

In this study multivariate analysis was adopted to establish how simultaneous changes in heart rate (HR), blood pressure (BP) and work load (W) can affect systolic time intervals (STI). Thus, 13 normal volunteers underwent two consecutive exercise stress tests in the supine and upright position on a bicycle ergometer. By multivariate analysis it was shown that, while in the supine position left ventricular ejection time (LVET) is influenced by HR and W (LVET) = 330.6 - 0.76 HR - 0.41 W, F = 224, P is less than 0.001), in the upright position LVET changes are due only to HR variations (LVET = 309 - 0.88 HR, P is less than 0.001). Pre-ejection period (PEP) in both positions is related to HR and W, but this latter has a non-linear influence (supine: PEP = 110.9 - 0.15 HR -0.34 W + 0.0012 W(2), F = 56.4, P is less than 0.001; upright: PEP = 119 - 0.16 HR - 0.5 W + 0.0025 W(2), F = 86.7, P is less than 0.001). Finally, PEP/LVET ratio is correlated both in the supine and upright position with maximal BP, HR and W; however, the influence of HR and BP is different in the two positions (supine: PEP/LVET = 0.259 + 0.00047 BP + 0.00068 HR - 0.00167 W + 0.000013 W(2), F = 5.68, P is less than 0.01; upright: PEP/LVET = 0.201 + 0.0011 HR - 0.00371 W + 0.00016 W(2), F = 4.79, P is less than 0.01).

Adolescent↗
PubMed1979

[Routine clinical use of a new disposable bubble oxygenator: a comparative study (author's transl)].

The new bubble Oxybel oxygenator (Bellco Laboratories) has been used for routine clinical perfusions in this Institution. A comparison has been made between two groups of 51 patients each, one group perfused with on Oxybel oxygenator (OXY) and the other with the Harvey H 1000 oxygenator (H-H). Among these patients a wide range of acquired and congenital cardiac lesions have been encountered. Both series were comparable for patients' age, sex distribution, body weight, procedures performed, perfusion time and preoperative values of hematocrit, serum creatinine, platelet count, plasma hemoglobin. The gas/blood flow ratio was 2.09 +/- 0.07 (+/- SE) for the H-H oxygenator and 1.38 +/- 0.06 for the OXY series (P < 0.001). Serum-creatinine 24-hrs postoperative values (mg/100 ml) were 1.58 +/- 0.17 for the H-H and 1.30 +/- 0.06 for the OXY series (NS); 48-hrs postoperative values were 1.28 +/- 0.11 for the H-H and 1.20 +/- 0.11 for the OXY (NS). The 60 minutes postoperative platelet count was 127.9 +/- 7 X 10(3) for the H-H and 120.9 +/- 6 X 10(3) for the OXY series (NS). Fourtyeight-hrs postoperative platelet count was 153.0 +/- 5 X 10(3) for the H-H and 151.8 +/- 6 X 10(3) for the OXY series (NS). Postoperative plasma hemoglobin values (mg/100 ml) were 91.55 +/- 7.18 for H-H and 117 +/- 17.8 for the OXY series (NS). Total postoperative bleeding was 1037.9 +/- 94 ml in the H-H and 1056.7 +/- 98.9 ml in the OXY series (NS). The more favorable gas/blood flow ratio observed with the Oxybel oxygenator did not affect clinical and haematologic results. These were comparable in both series.

Adult↗