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Biomedical subjects

H M Staniloff

Publications and source records attributed to H M Staniloff.

18 recordsLinked to original sources
PubMed1986

Variable spectrum and prognostic implications of left and right ventricular ejection fractions in patients with and without clinical heart failure after acute myocardial infarction.

To determine the spectrum and prognostic implications of left and right ventricular (LV and RV) ejection fractions (EFs) in acute myocardial infarction (AMI), radionuclide ventriculography was performed in 114 consecutive patients, admitted without (Killip class I, 78 patients) or with (killip class II, 36 patients) clinical signs of pulmonary congestion within 24 hours of onset of symptoms of a transmural AMI. Mean LVEF was significantly lower in patients in Killip class II than in those in class I (0.32 +/- 0.11 vs 0.46 +/- 0.15, p less than 0.001) and in patients with anterior than inferior AMI (0.34 +/- 0.11 vs 0.52 +/- 0.14, p less than 0.001). Of the 36 patients with a severely depressed (0.30 or less) LVEF, 15 (42%) were in Killip class I. Mean RVEF did not differ significantly between Killip class I and II patients (0.42 +/- 0.11 vs 0.40 +/- 0.12, difference not significant) but was significantly lower in patients with inferior than anterior AMI (0.38 +/- 0.09 vs 0.44 +/- 0.11, p = 0.005). In patients with inferior AMI, a depressed RVEF (0.38 or less) was associated with a normal LVEF in 30% and a depressed LVEF in 20%, whereas in those with anterior AMI, a depressed RVEF, observed in 25% of patients, occurred only in association with a depressed LVEF.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

A model for assessing the sensitivity and specificity of tests subject to selection bias. Application to exercise radionuclide ventriculography for diagnosis of coronary artery disease.

A probabilistic model was developed which allows one to estimate sensitivity and specificity of diagnostic tests for coronary artery disease without reference to angiography. The feasibility of the model was evaluated first in a series of computer simulations, and the model was then applied to the assessment of ejection fraction in 933 patients without prior myocardial infarction who underwent exercise radionuclide ventriculography. In 196 patients who were referred to angiography, the conventional abnormal ejection fraction criterion--an absolute rise of less than 0.05 with exercise--had a sensitivity of 79% and a specificity of 68% when referenced to coronary angiography. In 737 patients who were not referred for angiography and who were analyzed instead by our probabilistic model, sensitivity was 63% (p = 0.004 compared to that in the 119 angiographically diseases patients) and specificity was 79% (p = 0.036 compared to that in the 77 angiographic normals). Both the higher sensitivity and lower specificity in the catheterized patients are consistent with a preferential referral of positive test responders to angiography, and of negative test responders away from angiography. The distortion of test sensitivity and specificity which results from this selection bias can be circumvented by substituting a probabilistic estimate of disease for conventional angiographic ascertainment.

Adult↗
PubMed1986

Extent and severity of myocardial hypoperfusion as predictors of prognosis in patients with suspected coronary artery disease.

The ability of exercise-induced myocardial hypoperfusion on thallium scintigraphy to predict coronary events was assessed in 1,689 patients with symptoms suggestive of coronary artery disease but without prior myocardial infarction or coronary artery bypass surgery. A total of 74 patients had a coronary event in the year after testing (12 cardiac deaths, 20 nonfatal infarctions and 42 referrals for bypass surgery more than 60 days after testing). Stepwise logistic regression identified only three independent predictors: the number of myocardial regions with reversible hypoperfusion (an index of the extent of hypoperfusion), the maximal magnitude of hypoperfusion (an index of the severity of hypoperfusion) and the achieved heart rate (an index of exercise performance). Both extent and severity were exponentially correlated with event rate (r greater than 0.97 and p less than 0.01 for each), whereas achieved heart rate was linearly correlated with event rate (r = 0.79 and p less than 0.05). On the basis of these data, a prognostic model was defined that employs extent and severity as stress-dependent orthogonal variables. Using this model, the predicted coronary event rate ranged over two orders of magnitude--from a low of 0.4% in patients able to exercise adequately without developing severe and extensive hypoperfusion at a low heart rate (less than 85% of their maximal predicted heart rate). Extent and severity of myocardial hypoperfusion, therefore, are important independent variables of prognosis in patients with suspected coronary artery disease.

Aged↗
PubMed1986

Myocardial contrast echocardiography: examination of intracoronary injections, microbubble diameters, and video-intensity decay.

Contrast echocardiographic assessment of blood flow within the myocardium requires standardization of contrast agents and echo image analysis. Sonicated contrast solutions containing small and relatively stable microbubble ultrasound reflectors were injected into coronary arteries of five dogs, and a newly developed computer assisted densitometric analysis of myocardial echo intensity decay was examined. The sonicated solutions included sorbitol 70%, dextrose 70%, and dextrose 50%, and myocardial contrast echo data were analyzed by applying an exponential decay index (T-1/2) to the digitized time intensity curves obtained with videodensitometric techniques. In 30 intracoronary injections selected for further analysis, sonicated sorbitol 70% demonstrated the most physiologic myocardial transit time with the smallest variability (6.0 +/- 2.0 seconds). Sonicated dextrose 70% and dextrose 50% solutions exhibited significantly prolonged and more variable transit times (11.4 +/- 4.0 seconds and 13.9 +/- 5.0 seconds). The results of this study suggest that appropriate echo contrast solutions with small microbubble diameters are critical to satisfactory echocardiographic assessment of myocardial blood flow, and that objective analysis of contrast two-dimensional echocardiographic images can be achieved with computer-assisted videodensity algorithms featuring standardized echo analysis of the time intensity data.

Animals↗
PubMed1986

Prediction of death, myocardial infarction, and worsening chest pain using thallium scintigraphy and exercise electrocardiography.

Although used extensively, there is little published information on the prognostic ability of exercise 201Tl scintigraphy. Accordingly, 1 yr after testing we contacted 819 patients without previous MI or CABG seen in our laboratory during a 2-yr period. Events were defined as death from a cardiovascular cause, nonfatal MI, or worsening clinical state requiring CABG. The event rate was 3.9 events per 100 patients per year. There was univariate prognostic information when comparing the highest and lowest categories as risk ratios for chest pain characteristics (2.7), sex (2.3), exercise duration (3.1), ST slope (2.5), and thallium pattern (11.6), intensity of perfusion defect (17.2), and number of abnormal regions (8.7). However, the strongest predictors were also the least common. Prognostic ability was improved by combining the results categorically, as the number of abnormal tests (13.9). The highest risk ratio, 20.5:1, was obtained by combining results through discriminant function analysis. We conclude that exercise thallium scintigraphy provides prognostic information, although the most predictive patterns are uncommon. Combining the results of multiple test results improves the prognostic ability.

Adult↗
PubMed1984

Current concepts in cardiac rehabilitation.

This article has presented the historical basis for cardiac rehabilitation and the available data related to the four most important questions that remain: (1) Does exercise increase survival after myocardial infarction? Although it is generally thought that clinical trials have failed to demonstrate that cardiac rehabilitation prolongs life after a myocardial infarction, analysis of pooled data from all published studies shows that this conclusion is unjustified. (2) Can each individual patient's risk for a future cardiac event be determined? We have developed a method using serial application of Baye 's theorem to determine each patient's risk. By so doing, we can stratify patient groups by previous risk and then assess the effect of cardiac rehabilitation on altering risk without limiting the analysis to subsequent myocardial infarction and cardiac death. (3) Can regression of atherosclerosis be demonstrated? Regression of atherosclerosis has been clearly demonstrated in animal models, but new evidence suggests that it can also occur in human subjects. (4) Do all patients require monitored exercise after a myocardial infarction? Evidence documenting the safety of exercise in patients recovering from a myocardial infarction has resulted in inclusion of sick patients in cardiac rehabilitation programs and exercise of the healthier patients in unmonitored settings. Major changes in cardiac rehabilitation programs are now taking place, with the emphasis moving away from prolongation of life toward improvement in the quality of life. As a result, cardiac rehabilitation is no longer confined to exercise alone; equal emphasis is placed on dietary and psychologic aspects of patient recovery.

Arteries↗
PubMed1983

Computer-assisted diagnosis in the noninvasive evaluation of patients with suspected coronary artery disease.

A microcomputer program called CADENZA, which employs Bayes' theorem to analyze and report the results of various clinical descriptors and noninvasive tests relative to the diagnosis of coronary artery disease, was evaluated in 1,097 consecutive patients without previous myocardial infarction. With this program, each patient was characterized by a probability for coronary artery disease, based on Framingham risk factor analysis, symptom characterization, electrocardiographic stress testing, cardiokymography, cardiac fluoroscopy, thallium perfusion scintigraphy and technetium equilibrium-gated blood pool scintigraphy. A total of 11,808 probability estimates derived from various combinations of the available observations were analyzed: 2,180 in 170 patients undergoing coronary angiography and 9,628 in 969 patients who completed a 1 year follow-up for coronary events. The predicted probability of disease correlated linearly with observed angiographic prevalence in the 170 patients who subsequently had coronary angiography (prevalence = [0.001 +/- 0.011] + [0.966 +/- 0.019] X probability). The difference between probability and prevalence averaged 3.1%, and the magnitude of this correlation was not affected by the type or amount of data analyzed. The prevalence of multivessel disease in these patients increased as a monotonic function of disease probability. Below a probability of 25%, single vessel disease was slightly more common than multivessel disease. Above a probability of 75%, multivessel disease predominated. In the 969 patients followed up for 1 year from the date of testing, the incidence of cardiac death and nonfatal infarction increased as a cubic function of disease probability (from approximately 0 to 8% per year for each). Above a probability of 90%, however, the standard deviation for predicting these events was wide. These data indicate that Bayes' theorem in general--and CADENZA in particular--is an accurate, clinically applicable means for quantifying the prevalence of angiographic coronary artery disease, the risk of multivessel disease and the incidence of morbid coronary events in the year after testing.

Coronary Angiography↗
PubMed1982

Electrocardiographic abnormalities associated with malignant hyperthermia susceptibility.

Serial ECG's were reviewed in 93 consecutive patients who were proven to be susceptible to malignant hyperthermia by caffeine contracture and ATP depletion tests on skeletal muscle biopsies, but who were without a history of pyrexic crises. There were 46 males and 47 females with a mean age of 33 years. Abnormal ECG's were found in 26 of the patients, with conduction defects in 14, repolarization abnormalities (non-specific ST-T changes) or "Q" waves in nine and increased voltages suggesting left ventricular hypertrophy in three (in the absence of hypertension). An abnormal ECG in a young patient may reflect malignant hyperthermia susceptibility.

Adult↗
PubMed1981

Improved assessment of inferior segmental wall motion by the addition of a 70-degree left anterior oblique view in multiple gated equilibrium scintigraphy.

Conventional anterior and 45-degree left anterior oblique (LAO) views are limited in the evaluation of inferior segmental wall motion by multiple gated equilibrium cardiac blood pool scintigraphy. This study evaluated the addition of a 70-degree LAO view by comparing scintigraphic and contrast ventriculography in 25 patients, of whom 17 demonstrated abnormal inferior wall motion. Abnormal inferior wall motion was correctly identified in only 10 of 17 patients in the anterior view, but in 16 of 17 patients in the 70-degree LAO view. The number of assessable inferior segments was improved from 58% in the anterior view to 98% in the 70-degree LAO view. When the inferior segments could be visualized in the anterior view, inferior wall motion was accurately assessed. The addition of the 70-degree LAO view aids in the multiple gated equilibrium scintigraphic detection of inferior wall motion abnormalities with a minor loss in specificity.

Adult↗
PubMed1981

Application of information theory to clinical diagnostic testing. The electrocardiographic stress test.

The inherent imperfection of clinical diagnostic tests introduces uncertainty into their interpretation. The magnitude of diagnostic uncertainty after any test may be quantified by information theory. THe information content of the electrocardiographic ST-segment response to exercise, relative to the diagnosis of angiographic coronary artery disease, was determined using literature-based pooled estimates of the true- and false-positive rates for various magnitudes of ST depression from less than 0.5 mm to greater than or equal to 2.5 mm. This analysis allows three conclusions of clinical relevance. First, the diagnostic information content of exercise-induced ST-segment depression, interpreted by the standard 1.0-mm criterion, averages only 15% of that of coronary angiography. Second, there is a 41% increase in information content when the specific magnitude of ST-segment depression is analyzed, as opposed to the single, categorical 1-mm criterion. Third, the information obtained from ECG stress testing is markedly influenced by the prevalence of disease in the population tested, being low in the asymptomatic and typical angina groups and substantially greater in groups with nonanginal chest pain and atypical angina. The quantitation of information has broad relevance to selection and use of diagnostic tests, because one can analyze objectively the value of different interpretation criteria, compare one test with another and evaluate the cost-effectiveness of both a single test and potential testing combination.

Electrocardiography↗
PubMed1980

Application of conditional probability analysis to the clinical diagnosis of coronary artery disease.

Analysis of multiple noninvasive tests offers the promise of more accurate diagnosis of coronary artery disease, but discordant test responses can occur frequently and, when observed, result in diagnostic uncertainty. Accordingly, 43 patients undergoing diagnostic coronary angiography were evaluated by noninvasive testing and the results subjected to analysis using Bayes' theorem of conditional probability. The procedures used included electrocardiographic stress testing for detection of exercise-induced ST segment depression, cardiokymographic stress testing for detection of exercise-induced precordial dyskinesis, myocardial perfusion scintigraphy for detection of exercise-induced relative regional hypoperfusion, and cardiac fluoroscopy for detection of coronary artery calcification. The probability for coronary artery disease was estimated by Bayes' theorem from each patient's age, sex, and symptom classification, and from the observed test responses. This analysis revealed a significant linear correlation between the predicted probability for coronary artery disease and the observed prevalence of angiographic disease over the entire range of probability from 0 to 100% (P less than 0.001 by linear regression). The 12 patients without angiographic disease had a mean posttest likelihood of only 7.0 +/- 2.6% despite the fact that 13 of the 60 historical and test responses were falsely "positive." In contrast, the mean posttest likelihood was 94.1 +/- 2.8% in the 31 patients with angiographic coronary artery disease, although 45 of the 155 historical and test responses were falsely "negative." In 8 of the 12 normal patients, the final posttest likelihood was under 10% and in 26 of the 31 coronary artery disease patients, it was over 90%. These estimates also correlated well with the pooled clinical judgment of five experienced cardiologists (P less than 0.001 by linear regression). The observed change in probability for disease for each of the 15 different test combinations correlated with their information content predicted according to Shannon's theorem (P less than 0.001 by linear regression). These results support the use of probability analysis in the clinical diagnosis of coronary artery disease and provide a formal basis for comparing the relative diagnostic effectiveness and cost-effectiveness of different test combinations.

Adult↗
PubMed1978

Technetium-99m stannous pyrophosphate scintigraphy in patients with calcification within the cardiac silhouette.

Technetium-99m stannous pyrophosphate scintiscanning was performed in 22 patients with radiographically detected calcification within the cardiac silhouette. All but one of these scintigrams showed a localised area of increased activity similar to that ordinarily seen in acute myocardial infarction. Scintiscans in 3 patients after removal of the calcified aortic valve reverted to negative. It was concluded that this technique for acute infarct detection may yield false positive results in the presence of cardiac calcification.

Calcinosis↗
PubMed1978

Cardiac manifestations of malignant hyperthermia susceptibility.

Malignant hyperthermia is a disease resulting from defective cellular membranes, usually presenting as drug-induced pyrexic crises. We describe four patients with life threatening ventricular arrhythmias or chest pain in the absence of pyrexic crises. Three presented with life threatening arrhythmias and the fourth with severe atypical chest pain. Two patients had a family history of multiple sudden deaths. Resting CKs were elevated in three patients while CK-MB was elevated in one. Resting ECGs were abnormal in three. Three patients had recurrent ventricular tachycardia, two had recurrent ventricular fibrillation and multiple cardiac arrests. Cardiac catheterization showed abnormal left ventricular wall motion in two and minimal mitral valve prolapse in one while all had normal coronary arteries. Thallium-201 myocardial imaging demonstrated large perfusion defects in the patient with electrocardiographic Q waves and normal coronary arteries. Myocardial involvement has been demonstrated by clinical, electrocardiographic, hemodynamic, angiographic and myocardial imaging abnormalities. Malignant arrhythmias occurred in these patients in the absence of pyrexic crises or drug admininstration. Abnormal calcium release in the myocardium, as documented in skeletal muscle membranes, may be a unifying concept for the various manifestations described.

Adult↗