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Biomedical subjects

R A Podolin

Publications and source records attributed to R A Podolin.

5 recordsLinked to original sources
PubMed1990

Detection and quantitation of ischemic left ventricular dysfunction using a new video intensity technique for regional wall motion evaluation.

Eighty patients with ischemic heart disease and 17 normal subjects were evaluated for left ventricular regional wall motion by means of a new method. The wall motion analysis is based on video intensity. This technique uses a temporally sliding analysis to evaluate the cardiac cycle in 100 msec intervals. Presence of coronary artery disease was defined as more than 50% measured diameter stenosis. Wall motion abnormalities in regions perfused by stenotic vessels were most common in early diastole (76%). Sensitivity of this method at rest in patients with coronary artery disease was 79.7% (p less than 0.0001) and overall accuracy was 84.2% (p less than 0.0001). Abnormalities in both systole and diastole were more common in regions perfused by severe lesions (greater than 75%) than in those perfused by moderately stenotic (less than 75%) vessels (p less than 0.05). A comparison of the new method with phase and amplitude analysis was performed in 15 patients and with two-frame analysis in 40 patients. This new method yielded a higher sensitivity than either of the other two methods.

Adult↗
PubMed1990

Intracoronary urokinase for intracoronary thrombus accumulation complicating percutaneous transluminal coronary angioplasty in acute ischemic syndromes.

Intracoronary urokinase was used to treat flow-limiting intracoronary thrombus accumulation that complicated successful percutaneous transluminal coronary angioplasty (PTCA) during acute ischemic syndromes in 48 patients who were followed up through the acute phase of their illness. The study group comprised 10 patients with unstable angina pectoris, 18 patients with an evolving acute myocardial infarction, and 20 patients with postinfarction angina. The initial mean percent coronary diameter stenosis for the entire population was 95 +/- 7% and decreased with initial PTCA to 41 +/- 20% (p less than 0.001), with improved corresponding coronary flow by Thrombolysis in Myocardial Infarction trial (TIMI) grade. However, thrombus accumulation then resulted in a significant increase in percent diameter stenosis to 83 +/- 17% (p less than 0.001); a corresponding significant reduction in coronary flow also occurred by TIMI grade. After administration of intracoronary urokinase (mean dose, 141,000 units; range, 100,000-250,000 units during an average period of 34 minutes), with additional PTCA, mean percent diameter stenosis significantly decreased to 34 +/- 17% (p less than 0.001); a correspondingly significant improvement in mean coronary flow by TIMI grade occurred to 2.9 +/- 0.2. Overall, the angiographic success rate was 90%. There were no ischemic events requiring repeat PTCA and no procedure-related myocardial infarctions or deaths before hospital discharge. One patient was referred for urgent coronary artery bypass graft surgery after a successful PTCA. Plasma fibrinogen levels were obtained in 15 patients, and in no patient was the level below normal for our laboratory.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Combined hemodynamic and scintigraphic assessment of piroximone (MDL 19,205) and comparison with dobutamine and nitroprusside.

The acute hemodynamic responses to intravenous infusion of piroximone (MDL 19,205), a nonglycoside, noncatecholamine agent with positive inotropic activity in vitro, were compared with those of intravenous dobutamine and sodium nitroprusside, respectively, in 2 groups of patients with New York Heart Association class III or IV symptoms. Each drug was titrated to optimal dosage (dobutamine, 12.5 +/- 3.9 micrograms/kg/min; nitroprusside, 2.5 +/- 0.6 micrograms/kg/min; piroximone 1.4 +/- 0.6 mg/kg) and simultaneous hemodynamic and scintigraphic values were measured. In group 1, the increase in cardiac index was slightly greater with piroximone than with dobutamine (from 1.6 +/- 0.5 to 2.7 +/- 0.6 vs 2.4 +/- 0.6 liters/min/m2, p less than 0.025) and only piroximone significantly decreased left ventricular (LV) filling pressure (from 29 +/- 7 to 22 +/- 8 mm Hg, p less than 0.05). Both agents increased heart rate and systolic blood pressure. In group 2, cardiac index increased similarly with nitroprusside and piroximone (1.5 +/- 0.6 to 2.6 +/- 0.8 and 1.6 +/- 0.5 to 2.6 +/- 0.5 liters/min/m2, difference not significant), whereas LV filling pressure decreased slightly less with piroximone (29 +/- 7 to 24 +/- 10 vs 30 +/- 7 to 20 +/- 11 mm Hg, difference not significant). Only nitroprusside reduced mean arterial pressure (88 +/- 13 to 72 +/- 12 mm Hg, p less than 0.001 between drugs). In group 1, systolic blood pressure to end-systolic volume ratio increased in 9 of 10 patients taking both piroximone and dobutamine, whereas in group 2, this ratio increased in 7 of 8 patients taking piroximone and declined in 7 of 8 taking nitroprusside.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Influence of partial activation on force-velocity properties of frog skinned muscle fibers in millimolar magnesium ion.

Segments of briefly glycerinated muscle fibers from Rana pipiens were activated rapidly by a brief exposure to 2.5 mM free calcium followed by a solution containing calcium buffered with EGTA to produce the desired level of force. Steps to isotonic loads were made using a servomotor, usually 3-5 s after the onset of activation. The relative isotonic forces (P/P0) and velocities from contractions obtained under similar circumstances were grouped together and fitted with hyperbolic functions. Under the condition of 6 mM MgCl2 and 5 mM ATP, there was no significant difference in the relative force-velocity relations obtained at full activation compared with those obtained at partial activation when developed force was approximately 40% of its full value. Control experiments showed that a variety of factors did not alter either the relative force-velocity relations or the finding that partial activation did not change these properties. The factors investigated included the decline in force that occurs with each successive contraction of skinned fibers, the segment length (over a range of 1-3 mm), the sarcomere length (over a range of 1.9-2.2 microns), the magnesium ion concentration (26 microM and 1.4 mM were tested), the ATP concentration, the presence of free calcium, and the age of the preparation (up to 30 h). Attempts to repeat earlier experiments by others showing a dependence of shortening velocity on activation were unsuccessful because the low ionic strength used in those experiments caused the fibers to break after a few contractions. The main conclusion, that the shortening velocity is independent of the level of activation, is consistent with the hypothesis that the cross-bridges act independently and that activating calcium acts only as an all-or-none switch for individual cross-bridge attachment sites, and does not otherwise influence the kinetics of cross-bridge movement.

Adenosine Triphosphate↗