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Biomedical subjects

J N Karnegis

Publications and source records attributed to J N Karnegis.

At least 19 recordsLinked to original sources
PubMed1994

Relation between changes in severity of coronary artery stenosis and anginal patterns.

Although myocardial ischemia causes angina pectoris, angina and the severity of coronary artery stenosis in individuals do not correlate. However, changes in anginal status over time correlated with changes in the severity of coronary artery stenosis as determined by repeated coronary arteriograms has not been previously studied. Coronary arteriograms, done both at entry into the Program on the Surgical Control of the Hyperlipidemias (POSCH) and 3 years later, were blindly graded for changes in overall severity of coronary artery stenosis according to protocol by the POSCH Arteriography Review Committee. Arteriographic and clinical data from 376 control subjects (347 men, 29 women) were analyzed. There was no statistically significant relation over a long-term (3 year) period between the absence, presence, development, or disappearance of angina pectoris and changes in coronary artery stenosis severity as determined by coronary arteriography.

Analysis of Variance↗
PubMed1993

Serum creatinine as an independent predictor of coronary heart disease mortality in normotensive survivors of myocardial infarction. POSCH Group.

BACKGROUND: Serum creatinine has been reported in previous studies to be a prognostic indicator for overall mortality, in particular in a hypertensive population. METHODS: The Program on the Surgical Control of the Hyperlipidemias (POSCH) was a randomized, controlled clinical trial. All patients had survived a single myocardial infarction, were normotensive, were not obese, were not having heart failure, and were free of diabetes mellitus and renal disease at entry into the study. POSCH had followed its control group patients (N = 417) for a minimum of 7.0 years. In this group, a prospective post hoc analysis of the relationship of baseline serum creatinine with subsequent overall and atherosclerotic coronary heart disease mortality was performed. RESULTS: The baseline serum creatinine values in the control group patients ranged from 0.7 to 1.9 mg/dL (60 to 170 mumol/L), and were found to be independent predictors (P < .01) of both overall mortality and atherosclerotic coronary heart disease mortality. Each 0.1 mg/dL (9 mumol/L) increment in the baseline serum creatinine increased the relative risk for subsequent overall mortality by 36% and the relative risk for subsequent atherosclerotic coronary heart disease mortality by 47%. CONCLUSIONS: These results demonstrate that a serum creatinine value, obtained in normotensive, nonobese, normoglycemic survivors of a myocardial infarction without preexistent renal disease or heart failure, provides independent prognostic information regarding subsequent overall and atherosclerotic coronary heart disease mortality.

Adult↗
PubMed1992

Correlation of coronary with peripheral arterial stenosis. The POSCH Group.

Although it is known that patients with peripheral arterial disease are at high risk for coronary arterial stenosis, it is not known if, conversely, coronary artery disease correlates with peripheral arterial stenosis. In the Program on Surgical Control of the Hyperlipidemias (POSCH) coronary and aortic-iliac-femoral arteriograms were systematically analyzed. POSCH is a randomised, controlled secondary intervention clinical trial of hyperlipidemic subjects, ages 30-64 years with one myocardial infarction and angiographically demonstrable coronary arterial stenosis. Of the 838 subjects enrolled in the study, 436 had diagnostic visualization of both the coronary and aortic-iliac-femoral systems. The aortic-iliac-femoral arteries were normal in 44% (194/436) of the subjects. In contrast, only 9% (37/436) of the subjects had less than 50% stenosis of all 3 coronary arteries. However, there was a positive correlation between the severity of the stenosis, if present, in the aortic-iliac-femoral arteries and that in the coronary arteries (P less than 0.001). The subjects who did exhibit aortic-iliac-femoral arterial disease were significantly older and more frequently were cigarette smokers. We conclude that subjects with coronary arterial stenosis frequently are free of peripheral arterial disease.

Adult↗
PubMed1992

Accuracy of percussion of the left cardiac border.

UNLABELLED: The purpose of this study was to determine the accuracy of percussion of the left cardiac border. Sixty-six adult patients were studied. The left cardiac border as determined by percussion and marked with a calibrated lead marker was compared with that obtained by a chest X-ray. The error in locating the left cardiac border by percussion ranged from underestimating by 5.0 cm to overestimating by 5.5 cm. The mean absolute error was 1.6 cm (SD = 1.6 cm). In 74% (49/66) and 85% (56/66) of the patients the percussed border was within 1.0 and 2.0 cm, respectively, of that established by X-ray. In 24 of the 66 cases, a second examiner also independently percussed the left cardiac border. The differences between the location determined by the two observers ranged from 0 to 4 cm with a mean difference of 1.2 cm (SD = 1.0 cm). CONCLUSION: Percussion can accurately locate the left cardiac border in the adult patient and is a reproducible technique.

Adult↗
PubMed1991

Positive and negative exercise test results with and without exercise-induced angina in patients with one healed myocardial infarction: analysis of baseline variables and long-term prognosis.

The prognostic implications of exercise test results with and without exercised-induced angina are not completely understood. In the Program On the Surgical Control Of the Hyperlipidemias (POSCH), 838 subjects with hyperlipidemia who had one healed myocardial infarction were studied and followed for 6 to 13 years (mean 8.6). Of the 417 control subjects, 279 had a treadmill exercise test result that was definitely positive or negative. Angina was also induced by exercise in 30% (45/150) and 8% (10/129) of those with a positive and a negative test result, respectively (p less than 0.0001). The data showed no difference between subjects with a positive or a negative test result with or without angina as regards levels of blood lipids, type of myocardial infarction (Q or non-Q wave), left ventricular function, or prognosis as defined by death, atherosclerotic coronary heart disease death, or myocardial infarction.

Angina Pectoris↗
PubMed1990

Estimation of left ventricular ejection fraction with healed myocardial infarction by multiple regression analysis of electrocardiographic Minnesota Q-QS codes. POSCH Group.

The cardiac damage caused by a myocardial infarction may be evidenced by abnormal electrocardiographic Q-QS complexes (i.e., Minnesota Q-QS codes) and by impairment of left ventricular function. It has been shown that the level of significance of the Q-QS codes is highly correlated with the extent of left ventricular impairment. This study was directed to quantitating this relationship in subjects with a healed myocardial infarction and expressing it mathematically. Using multiple linear regression analysis, a coefficient value was obtained corresponding to the level of significance of each Q-QS code located in each electrocardiographic cardiac area. The left ventricular ejection fraction was estimated by subtracting the coefficient of the most significant code present in each cardiac area from the constant, which was calculated to be the ejection fraction in the absence of any Q-QS code. The results were reproducible, and there was a good correlation between the estimated and measured ejection fraction.

Adult↗
PubMed1987

Comparison of exercise-positive with recovery-positive treadmill graded exercise tests.

A treadmill exercise test response may become positive because a diagnostic electrocardiographic ST-segment shift occurred during exercise, or, less often, because it occurred only during the recovery period after exercise had been completed. Factors that may be related to these 2 different responses in subjects enrolled in the Program of Surgical Control of Hyperlipidemia were investigated. No differences were found with regard to age, sex, level or location of Minnesota electrocardiographic Q-QS codes, number of narrowed coronary arteries, presence of collateral coronary artery circulation, ejection fraction, number of abnormally moving left ventricular wall segments, heart rate, systolic and diastolic blood pressure, double product, total exercise time, exercise-induced angina, or maximally achieved exercise heart rate or double product. Thus, the same significance should be attributed to a recovery-positive as to an exercise-positive treadmill test, and electrocardiographic, hemodynamic and angiocardiographic variables do not distinguish between subjects who exhibit these 2 different responses.

Adult↗
PubMed1987

An example of expert systems applied to clinical trials: analysis of serial graded exercise ECG test data.

Clinical trials collect large amounts of data over time. The use of statistical methods to compare and interpret these serial data often fall short of complete evaluation because the analysis requires clinical judgment. As an alternative, some trials use individual experts or panels of experts to evaluate data, but this method usually requires the participation of clinicians who must spend large amounts of time performing tedious, repetitive tasks. The authors examined the use of expert systems to analyze serial clinical trial data where the analyses required use of clinical judgment. A prototype expert system was built to assess the data obtained from a pair of serial graded exercise ECG tests and reach a decision that would duplicate the decision reached by a cardiologist. The experiment was successful. Expert systems should be further developed and tested in other areas, such as serial coronary arteriography data.

Clinical Trials as Topic↗
PubMed1986

Relation between Q-QS changes on the rest electrocardiogram and left ventricular function with healed myocardial infarction.

In the Program of Surgical Control of Hyperlipidemia, the relation of the Minnesota Q-QS codes for rest electrocardiograms to left ventricular (LV) function was studied in patients with healed myocardial infarction (MI). Of 838 subjects enrolled in the study, 477 (57%) had codable Q-QS patterns at the time of randomization. There was an extremely high correlation between the level of the Minnesota code and concurrent LV function, the latter being determined on left ventriculography by both ejection fraction and the number of segmental wall motion abnormalities. Subjects without a Q-QS code had less myocardial damage than did those with a code present in a single cardiac area. Extent of LV damage correlated with the level of significance of the Q-QS code, and when the code was present in only 1 cardiac location damage was greatest if the anteroseptal area was involved. Q-QS codes present in 2 rather than 1 cardiac area were associated with an even greater degree of LV damage. A previous study has shown a strong correlation between LV function and the Minnesota codes when the latter were recorded 0.5 to 5 years (mean 2.2) earlier at the time of the acute MI. The present data show that the relation between LV function and the Minnesota codes after an acute MI persists over time and is even stronger when both are determined in the healed state at a time remote from the acute event.

Adult↗
PubMed1985

Quantitative assessment of left ventricular function after myocardial infarction using the minnesota Q-QS codes for resting electrocardiograms.

The electrocardiogram as a quantitative predictor of left ventricular systolic function was investigated in subjects with one myocardial infarction. The first 509 consecutive subjects to enter the Program of Surgical Control of Hyperlipidemia were studied by selective left ventriculography. Electrocardiograms taken during a prior hospitalization of the subjects for acute myocardial infarction were classified according to the Minnesota Q-QS codes. This study showed that the lower (ie, the more significant) Q-QS codes were highly correlated with reduced left ventricular function as measured both by a lower ejection fraction and by a greater number of left ventricular segments showing abnormal systolic motion. In addition, the location of segmental wall motion abnormalities correlated with the electrocardiographic site of the Q-QS code.

Adult↗
PubMed1985

Development and evolution of electrocardiographic Minnesota Q-QS codes in patients with acute myocardial infarction.

The development of ECG Minnesota Q-QS codes and their subsequent evolution were studied in the first 692 subjects to enter the POSCH program who had had one MI. The mean interval from MI to entry into the study was 2.2 years. Sixty-three percent of the subjects developed the most significant code with the infarction. By the time the subjects entered the study, the codes had commonly regressed to a lower level, disappearing altogether in 34%. The likelihood of complete regression varied inversely with the significance of the code. There was no significant difference between the groups with disappearance and with retention of a Q-QS code as to time since MI, the extent of coronary arterial disease, or the age or sex of the subject. In about half of the subjects the original code did not change with time and in 21% to 44% the code increased to one of a higher level of significance.

Adult↗
PubMed1983

Directional ST-segment deviation in graded exercise tests correlated with motion of the individual segments of the left ventricular wall.

An exercise test may be characterized as positive because of the production of either electrocardiographic ST-segment depression or elevation. The relationship of exercise-induced ST-segment deviation to the specific motion abnormalities of the individual segments of the left ventricular wall was investigated. The first 280 subjects to enter the Program of Surgical Control of Hyperlipidemia were studied by treadmill exercise testing and left ventriculography. The results showed that exercise-induced ST-segment elevation could occur without evidence in the resting subject of either dyskinesia or aneurysm of the left ventricle, that the area of left ventricular damage was much greater in subjects with exercise-induced ST-segment elevation than in those with ST-segment depression, and that wall motion abnormalities were concentrated in the inferoposterior area in the group with ST-segment elevation, but were generally scattered throughout the left ventricular wall in the group with ST-segment depression.

Adult↗
PubMed1981

Mitral regurgitation and characteristic changes in impedance cardiogram.

We have noted that the impedance cardiographic waveform of patients with mitral regurgitation may show typical abnormalities not found in other forms of cardiac disease, either valvular or congenital. In order to investigate this we reviewed the impedance cardiograms of all our patients who had also undergone cardiac catheterisation, and selected two groups both of which were inclusive and complete: (1) 22 patients with the diagnosis of normal heart, and (2) 36 patients with the diagnosis of isolated mitral regurgitation. An index was calculated algebraically from the change of impedance (delta L) tracing by adding together the height of the C wave and the height of the nadir of the X descent and subtracting the height of the V wave, that is delta Z index (in units of ohms) = C + X - V. The mean delta Z index for the normal group was 1.64 and for the mitral regurgitation group 0.96 ohms. Similarly, an index was calculated from the first time derivative of the change of impedance (dZ/dt) tracing, that is dZ/dt index (in units of ohms/s) = C' + X' - V'. The mean dZ/dt index for the normal group was 1.32 and for the mitral regurgitation group 0.48 ohms/s. Though there was some overlap of individual points between the two groups, the mean values for both the delta Z index and the dZ/dt index separated the group with mitral regurgitation from the normal group with a high level of statistical significance. We concluded that mitral regurgitation might be associated with a characteristic abnormality of the impedance cardiographic waveform. In addition, an index can easily be calculated from the tracings which may be useful in identifying patients with mitral regurgitation.

Adolescent↗
PubMed1979

The risk of diagnostic cardiovascular catheterization.

This report details a prospective study of the risk of diagnostic cardiac catheterization performed in a private, community hospital. Over the first 131 months of operation of our laboratory, 745 adult patients underwent diagnostic cardiac catheterization consisting of 2,676 various catheterization procedures. Six patients experienced seven major complications; two of these complications left a permanent deficit. There were no deaths during catheterization and none later which were attributable to it. The risk to the patient of having a major complication associated with a cardiac catheterization in our series was 0.8 per cent. The risk to the patient of having a major complication when a catheterization procedure was performed was 0.3 per cent. The risk of having a complication resulting in a permanent sequela was 0.07 per cent. We conclude that diagnostic cardiac catheterization can be accomplished with little risk to the patient, either of death or of other major complication.

Adolescent↗