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Biomedical subjects

M S Bilsker

Publications and source records attributed to M S Bilsker.

13 recordsLinked to original sources
PubMed1995

Effects of electrically-stimulated exercise and passive motion on echocardiographically-derived wall motion and cardiodynamic function in tetraplegic persons.

The purposes of the study were (1) to characterize left ventricular wall motion, and the cardiodynamic and metabolic responses during electrical stimulation cycle ergometry (ESCE) exercise in tetraplegic people; (2) to test whether these responses linger into the post-exercise recovery period; and (3) to test whether they differ from those imposed by lower extremity continuous passive motion (CPM). Subjects were six tetraplegic males aged 25.8 +/- 3.1 (mean +/- SD) years with spinal cord injuries of 6.7 +/- 3.5 years' duration at the C5 and C6 levels (Frankel classifications A and B). On randomized non-consecutive days, subjects underwent either 30 min of steady-state exercise using transcutaneous electrically-stimulated contractions of bilateral quadriceps, hamstring, and gluteus muscle groups, or 30 min of continuous passive motion at 50 rpm. Data were taken at rest, min 15 and 30 of treatment, and min 5, 15, and 30 post-treatment. Stroke volume (SV) was measured echocardiographically as the product of the left ventricular outflow tract area and the integrated area under the left ventricular outflow tract flow-velocity curve acquired by doppler ultrasound. This value was multiplied by heart rate (HR) to determine the cardiac output (CO). Oxygen consumption (VO2) was monitored spirometrically, with arteriovenous oxygen difference (a-vO2DIFF) computed algebraically. Data were analyzed using repeated measures within-subjects design anaysis of variance, with significance accepted at the 0.05 level. Results showed five subjects had small hyperkinetic ventricles at rest that became more dynamic during ESCE than CPM. Though no systolic dysfunction was noted, all but one subject exhibited some degree of septal hypokinesis at rest and during exercise, possibly indicative of left ventricular noncompliance. Significant effects of condition (ESCE vs CPM), trial (measurement time point), and their interaction, were observed for CO (P < 0.05, 0.01, and 0.0001, respectively), HR (P < 0.0001, 0.05 and 0.005, respectively), and VO2 (P < 0.001, 0.05 and 0.005, respectively). A significant trial and condition by trial interaction was found for a-vO2DIFF (P < 0.05 and 0.0001, respectively). No effects for condition, trial or their interaction were found for SV or BPDIAS. Electrical stimulation cycle ergometry-treated subjects achieved peak VO2 of 712 +/- 300 ml min-1, 2.63 times baseline, with 56% elevation of a-vO2DIFF. Cardiac output increased from 3.5 +/- 1.51 min-1 to 6.0 +/- 2.11 min-1, an elevation solely attributable to a 57% increase in HR. Thus, both CO and a-vO2DIFF accounted for elevated VO2 during ESCE.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1994

Unmasking a patent foramen ovale during recurrent paradoxical cerebral embolism.

A patient with an acute ischemic stroke had an interatrial septal aneurysm shown by transesophageal echocardiography. Interatrial shunting, compatible with a patent foramen ovale, was observed on a follow-up study after a second stroke. This was seen in association with a right atrial thrombus. This case illustrates that an interatrial septal aneurysm serves as a marker for potential interatrial shunting, which can lead to paradoxical cerebral embolism.

Cerebral Infarction↗
PubMed1989

Evidence of hyperthyroidism in apparently euthyroid patients treated with levothyroxine.

A concentration of serum thyroxine (T4) above the accepted normal range has recently been recognized to result from commonly prescribed replacement dosages of levothyroxine sodium. To determine if the high levels of serum T4 have undesirable metabolic effects, despite the fact that the subjects are accepted as euthyroid, we studied 28 patients receiving long-term levothyroxine therapy; 19 patients were considered to be receiving replacement dosages and nine suppressive dosages of levothyroxine. To assess the effect of levothyroxine on target tissue, we measured the thyrotropin response to protirelin and systolic time intervals obtained by simultaneous electrocardiography and echocardiography. Thyrotropin response to protirelin was suppressed in patients with elevated serum T4 levels and normal serum triiodothyronine levels. These patients also had shortened systolic time intervals typical of hyperthyroidism. Our data indicate that commonly given replacement dosages of levothyroxine may induce undesirable metabolic consequences and that these patients perhaps ought to be seen as having "subclinical hyperthyroidism." The prescribed dosage of levothyroxine as therapy for hypothyroidism is still frequently excessive.

Adolescent↗
PubMed1983

Congestive heart failure: echocardiographic insights.

This study was designed to assess the role of echocardiography in the evaluation and management of patients with the congestive heart failure syndrome. Fifty consecutive patients with congestive heart failure referred for echocardiography were evaluated. Thirty patients (60 percent) had ejection fractions under 50 percent (mean +/- SD 30 +/- 9 percent), left ventricular dilatation (6.5 +/- 0.7 cm), and normal wall thicknesses (1.0 +/- 0.2 cm). The echocardiographic findings were predictable on clinical grounds in 18 of the 30 patients (60 percent) and worse than clinically expected in 12 patients (40 percent). Management changes after echocardiography were indicated in 11 of 30 patients (37 percent). The remaining 20 of the 50-patient cohort (40 percent) had ejection fractions above 50 percent (mean 70 +/- 9 percent, p less than 0.01), and, as a group, were characterized by normal left ventricular size (5.1 +/- 0.8 cm, p less than 0.01) and borderline wall thicknesses (1.1 +/- 0.2 cm, p less than 0.01). The largest subgroup of these 20 patients had hypertensive heart disease (seven patients, 35 percent) associated with the congestive heart failure syndrome presumably related to left ventricular diastolic (compliance) dysfunction. The normal ejection fraction was unexpected clinically in 18 of these 20 patients (90 percent). Recommended management after echocardiography changed in all 18 patients. Since standard clinical findings (history, physical examination, and chest roentgenography) failed to separate patients with normal and abnormal ejection fractions, or those in need of changes in management, echocardiography was a useful and, at times, essential part of the evaluation of these patients with the congestive heart failure syndrome.

Adult↗
PubMedDate not supplied

Determination of replacement and suppressive doses of thyroxine.

Suppression daily doses of thyroxine (T4) were determined and the daily amounts of T4 required to replace T4 were established in 217 hypothyroid patients. Patients with Hashimoto's thyroiditis treated daily with 2-3 micrograms/kg lean body mass or 1-2 micrograms/kg body weight T4 had normal serum thyrotrophin (TSH) concentrations, normal response to TSH-releasing hormone (TRH) and normal systolic time intervals but doses higher than 3 micrograms/kg lean body mass or 2 micrograms/kg body weight decreased serum TSH concentrations, with no response to TRH and systolic time intervals typical of hyperthyroidism. In 13/32 (41%) hypothyroid patients with Graves' disease following 131I and/or surgery, the daily T4 replacement dose was similar to that in Hashimoto's thyroiditis patients but in 12 (38%) patients daily doses of 2-3 micrograms/kg lean body mass or 1-2 micrograms/kg body weight T4 increased serum T4 and suppressed TSH levels, and in six (9%) lower doses were required to control hypothyroidism. The T4 suppression dose for patients with thyroid cancer was more than 3 micrograms/kg lean body mass or 2 micrograms/kg body weight, whereas approximately 30% of non-toxic nodular goitre patients required less than 3 micrograms/kg lean body mass. It is concluded that replacement or suppression doses of T4 should be individually determined and that different criteria should be applied for their calculation depending on the thyroid abnormality.

Dose-Response Relationship, Drug↗