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Biomedical subjects

P L McHenry

Publications and source records attributed to P L McHenry.

At least 19 recordsLinked to original sources
PubMed1989

Exercise echocardiographic detection of coronary artery disease in women.

The utility of exercise echocardiography for the diagnosis of coronary artery disease has been demonstrated in populations consisting largely of men with a high prevalence of disease. To determine the diagnostic value of exercise echocardiography in women, 57 women who presented with chest pain were studied with coronary cineangiography and echocardiography combined with either treadmill (n = 38) or bicycle exercise (n = 19). Significant coronary artery disease (greater than or equal to 50% reduction in luminal diameter) was present in 28 (49%) of 57 patients, including 16 (84%) of 19 who had typical angina, and 12 (32%) of 38 who had atypical chest pain. The overall sensitivity and specificity of echocardiography were both 86%. Exercise echocardiography correctly determined the presence or absence of coronary artery disease in 32 (84%) of 38 patients who had atypical chest pain and in 17 (89%) of 19 who had typical angina (p = NS). The exercise electrocardiogram (ECG) was nondiagnostic in 17 patients (30%) who had rest ST segment depression or ST depression with exercise that could also be induced by hyperventilation or changes in position. The correct diagnosis was made by echocardiography in 14 (82%) of 17 patients with a nondiagnostic exercise ECG. In conclusion, exercise echocardiography has a clinically useful level of sensitivity and specificity for the detection of coronary artery disease in women. The technique provides diagnostic information in women presenting with atypical chest pain and in those who have a nondiagnostic exercise ECG.

Adult↗
PubMed1987

Usefulness of Q-wave response to exercise as a predictor of coronary artery disease.

In lead CM5, the Q-wave response to exercise has been reported as an effective index in predicting coronary artery disease (CAD) and CAD with left anterior descending (LAD) disease. The purpose of this study was to verify these findings when the Q wave was analyzed in lead CC5 in 135 patients. The sensitivity for abnormal ST depression was 77%, specificity 83% and predictive value 78%. The corresponding values for the abnormal Q-wave response (reduction or no change in Q-wave amplitude) were 70%, 61% and 59%. These differences (except sensitivity) were significant. When either a positive ST or Q-wave response was used, sensitivity, specificity and predictive value did not significantly increase compared with the ST segment alone. In addition, only 45% of normal subjects with false-positive ST depression had a normal Q-wave response (increase) and 57% of patients with false-negative ST responses had an abnormal Q-wave response. When a positive response for CAD with an LAD lesion and for multivessel CAD with LAD narrowing was defined as having a Q-wave reduction, the sensitivities were extremely low (15% and 17%), but both the specificities and the predictive values were 100%. Therefore, the Q-wave analysis in lead CC5 is no more sensitive for detecting CAD than the ST-segment response. However, when a decreased Q-wave amplitude is observed, multivessel CAD and LAD narrowing can be predicted.

Coronary Disease↗
PubMed1986

Complementary value of two-dimensional exercise echocardiography to routine treadmill exercise testing.

Two-dimensional echocardiograms were done during rest and after exercise in 95 patients who subsequently had coronary arteriography. Prior myocardial infarction was present in 36 patients, 35 of whom had wall motion abnormalities. There was no evidence of prior infarction in 59 patients, 44 of whom had coronary disease. In these 44 patients, the exercise electrocardiogram showed ischemia in 19, was normal in 13, and was nondiagnostic in 12. Exercise echocardiograms were abnormal in 35 of these 44 patients. In 15 patients without coronary disease, the treadmill response was nondiagnostic in 6, ischemic in 1, and normal in 8. Exercise echocardiograms were normal in 13 of these 15 patients. We conclude that exercise echocardiography is a valuable addition to routine treadmill testing. It may be of special value in patients with an abnormal resting electrocardiogram or a nondiagnostic response to treadmill testing or when a false-negative treadmill test is suspected.

Adult↗
PubMed1985

Behavior of the terminal T wave during exercise in normal subjects, patients with symptomatic coronary artery disease and apparently healthy subjects with abnormal ST segment depression.

The Q-T interval and apex of T wave to end of T wave (aT-eT) interval were measured by computer in four age-matched study groups at rest and during exercise to determine whether: the behavior of the aT-eT interval differs in patients with myocardial ischemia when compared with normal subjects, and the behavior of the aT-eT interval differs in subjects with true positive and false positive ST segment responses. Group I consisted of 57 normal subjects. Group II consisted of 41 symptomatic patients with documented coronary artery disease. A group of apparently healthy subjects with asymptomatic ST segment depression during exercise was divided into two additional groups: Group III, those without coronary artery disease; and Group IV, those with coronary artery disease. Subjects were excluded from the study if they had left ventricular hypertrophy or an intraventricular conduction defect or were taking digitalis or type I antiarrhythmic agents. There were no significant differences in the aT-eT interval and aT-eT/Q-T ratio among the four study groups when compared at rest; however, during exercise at similar heart rates, the aT-eT interval was significantly shorter and the aT-eT/Q-T ratio significantly smaller in Groups II and IV, the subjects with coronary artery disease, than in Group I, the normal subjects. The aT-eT interval and aT-eT/Q-T ratio measurements in Group III did not differ from those in Group I at rest or during exercise. In conclusion, the aT-eT interval and aT-eT/Q-T ratio may reflect changes in myocardial repolarization in exercise-induced ischemia and may have potential for future clinical application.

Adrenergic beta-Antagonists↗
PubMed1985

Role of exercise testing in predicting sudden death.

The exercise test can be utilized to identify a subset of patients with coronary heart disease who are at increased risk of subsequent cardiac mortality including sudden cardiac death. The exercise test variables that best identify these high risk patients differ according to clinical subsets, but exercise duration, ST segment depression and ventricular arrhythmias on the electrocardiogram are the most important variables. In the clinical setting, the exercise test is of limited value for identifying the patient at risk for developing sudden cardiac death because its sensitivity and specificity are not high enough. However, the exercise test does provide prognostic information that is independent of other clinical variables and it may prove to be of clinical utility when combined with multiple other prognostic variables.

Arrhythmias, Cardiac↗
PubMed1985

Ambulatory electrocardiographic monitoring: can we predict sudden death?

Cardiac arrhythmias can be accurately detected and quantified using ambulatory electrocardiographic monitoring. From a review of major studies, it appears that the presence of advanced ventricular arrhythmias identifies a subset of patients with coronary heart disease who are at a relatively higher risk for sudden death than are those patients without such arrhythmias. Left ventricular dysfunction is an independent and additive risk factor for subsequent development of sudden cardiac death. The presence of high grade ventricular arrhythmias appears to increase the risk for sudden death in patients with hypertrophic and dilated cardiomyopathy. Ambulatory monitoring can be used to identify a subset of patients with coronary disease or cardiomyopathy who are at increased risk for sudden cardiac death. Because of the relatively low overall incidence of sudden cardiac death in such patients, and the low sensitivity and specificity for accurately classifying patients, the practical applicability of this technique to large population subgroups is limited.

Adult↗
PubMed1984

The abnormal exercise electrocardiogram in apparently healthy men: a predictor of angina pectoris as an initial coronary event during long-term follow-up.

A group of 916 apparently healthy men between the ages of 27 and 55 years (mean 37) were followed up with serial medical and exercise test evaluations for a period of 8 to 15 years (mean 12.7) to determine (1) the prevalence and specific types of new coronary events observed in subjects with and without abnormal ST segment responses to exercise and (2) the predictive value of a serial conversion to an abnormal ST segment response to exercise for new coronary events. During the initial evaluation there were 23 subjects (2.5%) with an abnormal ST segment response to exercise. During follow-up there were nine (39%) coronary events in this group: eight cases of angina and one of sudden death. With serial testing, an additional 38 subjects (5.1%) experienced conversion to an abnormal ST segment response to exercise. During follow-up there were 12 (32%) coronary events in this group: 10 cases of angina, one of myocardial infarction, and one other. There were 833 subjects with normal ST segment responses to exercise with all tests. In this group there were 44 (5.3%) coronary events: 25 cases of myocardial infarction, seven of sudden death, and 12 of angina. We conclude that in apparently healthy middle-aged men an abnormal ST segment response to exercise is predictive of angina pectoris but not of myocardial infarction or sudden cardiac death as an initial coronary event.

Adult↗
PubMed1982

Prevalence and magnitude of S-T segment and T wave abnormalities in normal men during continuous ambulatory electrocardiography.

Fifty asymptomatic normal male volunteers, mean age 44.6 years (range 35 to 59), were prospectively studied to ascertain the prevalence and magnitude of S-T segment and T wave changes detected during continuous ambulatory electrocardiographic monitoring. Transient S-T segment depression of 1.0 mm or more was recorded in 15 (30 percent) of the subjects, and labile T wave inversion of up to 3 mm occurred in an additional 18 (36 percent). The presence of ST-T changes during monitoring did not correlate with age, daily activity status or heart rate. There was also no correlation with the S-T segment response or work performance during treadmill exercise testing. It is concluded that S-T segment depression and T wave inversions are commonly observed during ambulatory electrocardiographic monitoring of normal men. Therefore, similar changes observed in patients with coronary artery disease should be interpreted with caution.

Adult↗
PubMed1981

Computer quantitation of Q-T and terminal T wave (aT-eT) intervals during exercise: methodology and results in normal men.

Computer-quantitated measurements of the Q-T intervals, the Q-T/Q-Tc ratio (Q-T/corrected Q-T) and the terminal T wave (apex to end of T [aT-eT] interval) were evaluated in resting and exercise electrocardiograms of 130 normal men with a mean age of 40 years. Pseudo-orthogonal, bipolar X, Y and Z axis leads were recorded during treadmill exercise testing, and 25 consecutive QRS-T complexes from standing rest and three exercise stages were computer-averaged. The Q-T intervals, Q-T/Q-Tc ratio and aT-eT interval measurements were then computed in the X and Z axis leads only, because the Y lead proved to be too noisy for accurate interpretation. A correlation coefficient of 0.9830 resulted between measurements made manually from the plotted, composite QRS-T complexes and those made by computer. No significant differences , in the paired sense, were found between any of the measurements. Measurements made on the Z axis lead; however, the differences in the measurements remained constant across all stages of exercise. A Q-T/Q-Tc ratio of greater than 1.08, previously reported to be a reliable indicator of coronary disease, was observed in the majority of our normal subjects during exercise. Although the Q-T interval is substantially influenced by many factors, the aT-eT interval proved not to be age- or heart rate-dependent. It appears that the aT-eT interval can be measured with a high degree of reliability during exercise and it may prove to be a relatively specific indicator of repolarization alterations that occur with myocardial ischemia.

Adult↗
PubMed1981

Acute and chronic haemodynamic effects of prazosin in left ventricular failure.

We evaluated the acute and chronic effects of prazosin treatment in 11 patients with chronic congestive heart failure, NYHA functional class III and IV. Before treatment mean arterial pressure averaged 100 +/- 15 mmHg, left ventricular filling pressure 29 +/- 11 mmHg, and systemic vascular resistance 2372 +/- 1121 dynes s cm-5. Prazosin administration resulted in haemodynamic improvement in all but one patient with significant lowering of the mean arterial pressure, left ventricular filling pressure, and systemic vascular resistance. Nine patients completed a 10-week course of ambulatory treatment. Five patients remained improved while four developed significant fluid retention; two of these had transient exacerbation of congestive heart failure. This was controlled by increasing diuretic and/or prazosin treatment. After 10 weeks all nine patients had advanced to NYHA functional class II. Repeat haemodynamic measurements disclosed complete haemodynamic tolerance in one patient while three other patients showed partial tolerance with a lower cardiac output (CO) response to prazosin. The nine patients, however, still showed significant lowering of the mean arterial pressure, left ventricular filling pressure, as well as the systemic vascular resistance. Though pharmacodynamic tolerance was noted in four out of nine patients, beneficial clinical and haemodynamic effects could be demonstrated after 10 weeks of prazosin treatment in most patients. Further evaluation of the long-term effects of prazosin in chronic congestive heart failure is warranted.

Aged↗
PubMed1980

Relation of exercise-induced physiologic S-T segment depression to R wave amplitude in normal subjects.

Exercise electrocardiography was performed in 100 asymptomatic male volunteers with a mean age of 42.6 years. The R wave and total RS amplitude and the magnitude of physiologic S-T segment depression at the J junction were quantitated for a modified bipolar CC5 lead and a vertically oriented bipolar lead (VL) using computer-averaged groups of 25 consecutive QRS complexes from each of seven stages of rest and exercise. Computer-generated X-Y plots were used to examine the correlations between the magnitude of S-T depression and the R wave and total RS amplitudes. The magnitude of S-T depression and of the R wave amplitude were unrelated at standing rest but showed increasing correlation with progressive increases in exercise heart rate (correlation coefficient = 0.425, p < 0.00001 at maximal exercise). The total RS amplitude was also related to the magnitude of S-T depression during exercise, but the correlations did not improve progressively with increases in exercise heart rate. The magnitude of S-T depression was more closely related to R wave amplitude and total RS amplitude in the vertically oriented lead than in the CC5 lead. These data demonstrate a significant relation between the magnitude of R wave and total RS amplitudes and the magnitude of physiologic S-T segment depression in normal subjects during exercise. They suggest the need for evaluation of S-T depression corrected for R wave amplitude in an attempt to improve the diagnostic accuracy of the exercise electrocardiogram. The data also suggest that the criteria for abnormal S-T depression should take into consideration the different R wave voltages reflected by different types of recording leads.

Adult↗
PubMed1980

Resting U wave inversion as a marker of stenosis of the left anterior descending coronary artery.

Resting 12-lead electrocardiographic records from 849 patients who underwent coronary cineangiographic studies were reviewed for U wave negativity without knowledge of the clinical data or angiographic results. In order to evaluate U wave negativity as an independent electrocardiographic sign, patients with significant Q waves in the anterior leads were excluded from the final data analysis leaving 760 patients. Twenty-seven patients had U wave negativity in leads I, aVL or V4 through V6. For the study population, the prevalence of coronary artery disease was 64 percent (484 or 760); the prevalence of significant left anterior descending or left main coronary artery stenosis was 46 percent (350 of 760); and the prevalence of angiographic left ventricular dysfunction was 41 percent (309 of 754). Among 27 patients with resting U wave negativity the prevalence of coronary artery disease was 89 percent (24 of 27); the prevalence of left anterior descending or left main disease was 89 percent (24 of 27); and the prevalence of angiographic left ventricular dysfunction was 80 percent (20 of 25). Among patients selected for coronary cineangiographic study, U wave negativity was a significant predictor (p < 0.001) of greater than or equal to 75 percent stenosis of the left anterior descending or left main coronary artery and of left ventricular dysfunction (p < 0.001).

Adolescent↗