PubMed Health⌕ Search

Biomedical subjects

G D Plotnick

Publications and source records attributed to G D Plotnick.

At least 55 records · Page 3Linked to original sources
PubMed1988

Clinical significance of radionuclide angiographically-determined abnormalities following acute blunt chest trauma.

Abnormalities of right and left ventricular ejection fraction and segmental wall motion may be detected by radionuclide angiography (RNA) following blunt chest trauma. Of 111 patients with blunt chest trauma who were admitted to a large regional shock trauma center and underwent combined first-pass and equilibrium gated RNA, abnormalities were present in 40 (36%). These abnormalities were confined to the right ventricle in 33 patients. There was a positive association between RNA abnormalities and the presence of right bundle branch block (10 of 40, p less than 0.05) and a negative association between RNA abnormalities and the finding of rib fractures (6 of 40, p less than 0.05). The in-hospital death rate of these patients was low (3 of 40 patients with an abnormal RNA and 2 of 71 patients with a normal RNA). Follow-up RNA was performed at 10 +/- 4 days in 26 of the 40 patients with initially abnormal scans, and 22 (85%) of the 26 had reverted to normal. Thus although RNA abnormalities appear common following blunt chest trauma, among patients who survive for more than 24 hours and who undergo subsequent RNA, the complication rate is low despite an abnormal scan. We conclude that routine RNA adds little to clinical management following acute blunt chest trauma.

Adult↗
PubMed1988

Effect of postural changes, nitroglycerin and verapamil on diastolic ventricular function as determined by radionuclide angiography in normal subjects.

Whereas improvement in diastolic function indexes in response to therapeutic interventions has been attributed to a beneficial effect of the intervention, measurements of diastolic function appear to be influenced by changes in loading conditions, heart rate and sympathetic tone. To determine the effect of body position and short-term pharmacologic intervention on radionuclide angiographically determined left ventricular peak filling rate, high temporal resolution time-activity curves and absolute left ventricular volumes obtained by equilibrium-gated blood pool scans were evaluated in 12 normal subjects in the supine position at rest and in response to several postural and pharmacologic manipulations. This study confirmed the reproducibility of the technique and demonstrated that in normal subjects, peak filling rate varies in response to changes in body position and to short-term administration of sublingual nitroglycerin and intravenous verapamil. Peak filling rate ranged from 3.3 to 5.1 end-diastolic volumes (EDV)/s with a variability of 13.7% during five baseline supine measurements in the 12 subjects. Compared with values in the supine position (mean +/- SEM = 4.38 +/- 0.24 EDV/s), peak filling rate increased +16 +/- 6% to 4.75 +/- 0.27 EDV/s in the upright position (p less than 0.05) but did not change significantly with leg elevation. Peak filling rate at baseline and during postural changes correlated significantly with ejection fraction (r = +0.49), with stroke volume (r = +0.26) and inversely with end-systolic volume (r = -0.41), but did not correlate with heart rate or blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Changes in left ventricular function during recovery from upright bicycle exercise in normal persons and patients with coronary artery disease.

To characterize the hemodynamic changes during recovery after upright bicycle exercise, 56 normal subjects (group I) and 30 patients with documented myocardial ischemia (group II) were studied. Heart rate, blood pressure and radionuclide angiographically determined absolute left ventricular (LV) volumes were measured at baseline, peak exercise and 2 to 4.5 minutes and 4.5 to 7 minutes after upright bicycle exercise. Whereas ejection fraction and end-systolic volume responses at peak exercise differed between groups I and II, these parameters showed similar trends in both groups during recovery. Mean ejection fraction increased during 2 to 4.5 minutes in both groups, but remained elevated during 4.5 to 7 minutes only in normal subjects (group I). Elevation of cardiac output after exercise was accounted for predominantly by increased heart rate rather than increased stroke volume. Despite significantly decreased end-diastolic volume during recovery, stroke volume was maintained in both groups by a substantial decrease in end-systolic volume, suggesting the impact of decreased afterload or increased sympathetic tone during recovery. Thus, the Frank-Starling mechanism does not appear to be playing a major role during recovery after upright bicycle exercise, whereas enhanced contractility is evident in both normal subjects and patients with documented myocardial ischemia.

Adult↗
PubMed1986

Beta-blockers in congestive cardiomyopathy. Conceptual advance or contraindication?

The precise role of adrenergic activity in congestive cardiomyopathy has not been established. A number of mechanisms through which increased catecholamine levels may be harmful, along with the clinical and experimental evidence supporting this concept, are summarized in this review. In this context, the suggestion that beta blockers may be beneficial for patients with severe heart failure, despite their well-known propensity to decrease cardiac contractility, can be better understood. Published reports on the use of beta blocker therapy for congestive cardiomyopathy now include approximately 200 patients, but have yielded inconsistent results. Non-randomized trials in Sweden have suggested increased survival, with most patients having improved functional status while receiving beta blockade, although improvement may take three to six months to become evident. The Swedish group also reported clinical deterioration after discontinuation of beta blockade. Two recent randomized trials in America yielded promising results, but the unexpectedly low mortality in the placebo groups emphasizes the critical importance of concurrent controls. Unfavorable reports have involved small groups with short-duration therapy. Even in these reports, overt aggravation of clinical heart failure has been quite infrequent but sometimes profound. As large scale trials are undertaken, an obvious goal is the development of methods to differentiate the patients with congestive cardiomyopathy who will benefit in response to beta blocker therapy from the few patients who will have a serious adverse response.

Adrenergic beta-Antagonists↗
PubMed1986

Use of the Frank-Starling mechanism during submaximal versus maximal upright exercise.

To evaluate the extent to which the Frank-Starling mechanism is utilized during successive stages of vigorous upright exercise, absolute left ventricular end-diastolic volume and ejection fraction were determined by gated blood pool scintigraphy at rest and during multilevel maximal upright bicycle exercise in 30 normal males aged 26-50 yr, who were able to exercise to 125 W or greater. Left ventricular end-systolic volume, stroke volume, and cardiac output were calculated at rest and during each successive 3-min stage of exercise [25, 50, 75, 100, and 125-225 W (peak)]. During early exercise (25 W), end-diastolic and stroke volumes increased (+17 +/- 1 and +31 +/- 4%, respectively), with no change in end-systolic volume. With further exercise (50-75 W) end-diastolic volume remained unchanged as end-systolic volume decreased (-12 +/- 4 and -24 + 5%, respectively). At peak exercise end-diastolic volume decreased to resting level, stroke volume remained at a plateau, and end-systolic volume further decreased (-48 +/- 7%). Thus the Frank-Starling mechanism is used early in exercise, perhaps because of a delay in sympathetic mobilization, and does not appear to play a role in the later stages of vigorous exercise.

Adult↗
PubMed1985

Transcutaneous temporary pacing in the operating room.

The safety and efficacy of transcutaneous temporary pacing were assessed in 21 patients undergoing elective surgical procedures under general anesthesia. Complete capture was achieved in all patients. The pacing threshold was 50 mamp in two patients, 100 mamp in nine, and 200 mamp in ten. The threshold was influenced by electrode position and also, possibly, by age, heart size, and chest size. No adverse effects of pacing were encountered. Transcutaneous pacing is a rapid, safe, and effective means of temporary pacing in the operating room.

Adult↗
PubMed1985

Value and limitations of exercise radionuclide angiography for detecting myocardial ischemia in healed myocardial infarction.

Exercise radionuclide angiography was performed in 65 normal subjects (group I), in 31 patients with exercise-induced transient thallium defects after acute myocardial infarction (AMI) (group II), and in 16 patients without exercise-induced transient thallium defects, angina or electrocardiographic changes after AMI (group III). Absolute left ventricular (LV) volumes were measured using a correction for attenuation in each patient. Similar peak heart rate-blood pressure products were achieved in groups II and III. Although the mean LV ejection fraction (EF) response to exercise in group III (increase of 0.11 +/- 0.10 units) closely resembled that of normal persons (increase of 0.14 +/- 0.09 units) and was significantly different from that of group II (decrease of 0.04 +/- 0.12), there was considerable individual variation. An abnormal EF response to exercise, defined as failure of EF to increase by at least 0.05 units, was found in 6 subjects (9%) in group I, 26 patients (84%) in group II, and 2 patients (13%) in group III. End-systolic volume failed to decrease in 10 subjects (15%) in group I, 25 patients (81%) in group II and 7 patients (44%) in group III. New regional wall motion abnormalities were found in no subject in group I, in 16 patients (52%) in group II and in only 1 patient (6%) in group III. Thus, although group responses of EF or end-systolic volume appeared to correlate with the presence or absence of ischemia, some patients with exercise-induced transient thallium defects after AMI responded normally to exercise radionuclide angiography stress testing and some patients without other evidence of exercise-induced ischemia after AMI responded to exercise radionuclide angiography testing abnormally.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Routine preoperative exercise testing in patients undergoing major noncardiac surgery.

A prospective study of preoperative exercise testing was carried out in 200 patients older than 40 years scheduled for elective major noncardiac surgery under general anesthesia. The exercise test response was electrocardiographically positive in 32 patients (16%) (2 patients had a markedly positive test), equivocal in 11 patients (5.5%) and negative in 157 patients (78.5%). The patients were followed with serial pre- and postoperative electrocardiograms (ECGs) and determinations of serum creatine kinase (CK) and CK-MB. Six patients (3%) had primary endpoints: 3 (1.5%) died postoperatively and 3 (1.5%) had definite postoperative myocardial infarction. Secondary endpoints of suspected postoperative myocardial ischemia/injury diagnosed by ECG or elevation in CK-MB levels occurred in 27 patients (14%). Endpoint events were more common in patients aged 70 years or older. Endpoint events were also more common in patients with an abnormal (positive or equivocal) preoperative exercise test response than in those with a negative response (27% vs 14%); however, preoperative exercise results were not statistically significant independent predictors of cardiac risk. Using multivariate analysis, the only statistically significant independent predictor of risk was the preoperative ECG. Endpoint events were more common in patients with an abnormal than in those with a normal ECG (23% vs 7%, p less than 0.002). Because the results of exercise testing do not appear to add substantially to the risk separation provided by the ECG at rest, exercise testing is not recommended as a routine preoperative method for assessing perioperative risk in older patients who are being evaluated before major elective noncardiac surgery under general anesthesia.

Adult↗
PubMed1985

Technetium-99m-pyrophosphate scintigraphy in patients with suspected acute myocardial infarction: impact of interobserver variability.

Technetium-99m-pyrophosphate (TcPYP) scintigraphy may have great value in patients with suspected acute myocardial infarction (AMI), but interobserver variability undoubtedly has adverse impact on predictive value. TcPYP scintigrams for 133 (80%) of 166 consecutive patients admitted for suspected AMI were interpreted independently by three experienced readers. Although there was complete agreement for 87 interpretations (65%), major discrepancies (i.e., at least one positive and one negative reading on the same scan) occurred for 28 scans (21%). To assess predictive accuracy, patients were categorized as follows: 36 had definite AMI manifest by new ECG Q waves and/or CK-MB evidence of AMI (group I), 56 were classified as possible AMI (group II), and 41 had AMI excluded (group III). Using only the definitive diagnostic categories (groups I and III), accuracy for each reader approximated 0.68, with no single reader being correct more often than any other.

Creatine Kinase↗
PubMed1984

Improvement in depressed cardiac function in hypertensive patients during pindolol treatment.

To assess changes in left ventricular function during antihypertensive treatment using pindolol, a beta-adrenocepter blocking drug with potent intrinsic sympathomimetic activity, serial echocardiographic measurements were obtained in 70 hypertensive patients before and during 15 weeks of treatment with pindolol. For analysis, the patients were separated into three groups on the basis of their baseline left ventricular fractional shortening (Group I, 35 patients with normal fractional shortening of 28 percent or more; Group II, 16 patients with abnormal fractional shortening of 21 to 27 percent; and Group III, 19 patients with markedly abnormal fractional shortening of 20 percent or less). More than half of the patients in Group I and Group II had decreases in mean blood pressure of 10 percent or more in response to pindolol, but only one fourth of Group III patients had similar responses (p less than 0.05). Patients with normal pretreatment fractional shortening had a mild decrease in fractional shortening during pindolol treatment, whereas patients with either abnormal or markedly abnormal fractional shortening had an increase in fractional shortening. This increase in fractional shortening suggests the possibility that the partial agonist or intrinsic sympathomimetic activity of pindolol may play a role in preserving left ventricular function in patients with borderline or impaired function.

Adult↗
PubMed1984

A practical approach to exercise echocardiography: immediate postexercise echocardiography.

Echocardiographic measurements of left ventricular end-systolic dimension and fractional shortening obtained in the supine position before and immediately after maximal upright exercise were evaluated in 11 normal volunteers, 35 patients with coronary artery disease and 17 patients without coronary artery disease. The time course of recovery from acute exercise-induced changes in echocardiographic dimensions was analyzed using serial postexercise recordings from normal subjects. An exercise-induced decrease in end-systolic dimension (greater than or equal to 3 mm) and increase in fractional shortening (greater than or equal to 5%) persisted for 3 minutes or longer in the immediate postexercise period in each of the normal volunteers. With these criteria to separate normal from abnormal responses, abnormal responses were observed in 16 (94%) of 17 patients with coronary artery disease and in only 2 (6%) of 35 patients without coronary artery disease. Immediate postexercise echocardiography appears to be a practical and potentially valuable adjunct in the detection of coronary artery disease.

Adult↗
PubMed1984

Beta-blockers and hypertension: carbon copies or a real choice.

An extensive, almost overwhelming number of publications attest to the importance of beta-blockers and emphasize their role in a variety of clinical disorders. Despite uncertainty regarding the precise mechanism by which beta-adrenergic blocking drugs lower blood pressure, it is well established that these agents are fairly effective when used alone and are highly effective when combined with diuretics and/or vasodilators. Despite remarkably comparable efficacy, the available beta-blockers possess a variety of properties that may influence the frequency and type of untoward reactions. An approach to individualized choice of beta-blockers is outlined. It must be emphasized that our approach is in large part based on theoretical considerations, and further studies are needed to clearly define the relative likelihood of unwanted effects with each available agent.

Adrenergic beta-Agonists↗