Virinderjit S. Bamrah

Diagnostic Accuracy of Seismocardiography Compared with Electrocardiography for the Anatomic and Physiologic Diagnosis of Coronary Artery Disease During Exercise Testing

A multicenter study was performed to compare the diagnostic accuracy of a new technique, seismocardiography, with that of electrocardiography for physiologically and anatomically significant ischemic coronary artery disease (CAD) during exercise stress testing. Five participating centers enrolled 129 patients who had simultaneous seismocardiograms and 12-lead electrocardiograms at the time of their exercise treadmill stress tests. Two different definitions of CAD were used: anatomic and physiologically significant disease. The presence of anatomically significant CAD (> or = 50% diameter stenosis) was documented by coronary angiography. Physiologically significant CAD was defined as present in the same 129 patients when coronary arteriography (> or = 50% diameter stenosis) and thallium-201 scintigraphy (defect on initial postexercise images) were both abnormal. Seismocardiography had a significantly better sensitivity for detecting anatomic CAD than did electrocardiography (73 vs 48%; p < 0.001), without loss of specificity (78 vs 80%; p = NS). Exercise seismocardiography added significant incremental diagnostic information beyond that provided by exercise electrocardiography. Seismocardiography was more sensitive (without less specificity) in women and in patients who did not achieve maximal predicted heart rate. In patients with physiologically significant CAD, the seismocardiogram was also significantly more sensitive (78%) than was the electrocardiogram (55%) (p < 0.02), without loss of specificity (84 vs 74%). Seismocardiography significantly improved sensitivity for the detection of anatomic and physiologic CAD. It is easy to perform and may be a clinically useful adjunct in exercise stress testing.

Digital processing of contrast echocardiograms: A new technique for measuring right ventricular ejection fraction

Imaging of the right ventricle with 2-dimensional echocardiography (2-D echo) is hampered by trabeculation of the right ventricular (RV) endocardial surface and by limited echocardiographic resolution. Determination of RV ejection fraction (EF) is thus often an inconsistent and tedious procedure. The process of digital subtraction contrast echocardiography was developed to maximize echocardiographic definition of the right ventricle and to assess RVEF with minimal operator interaction. Videotaped 2-D echocardiograms recorded during i.v. injection of agitated saline were digitized. Masks were constructed from end-systolic and end-diastolic apical 4-chamber and parasternal RV short-axis images. Masks were subtracted from corresponding images recorded with contrast in the right ventricle; images of the contrast alone were extracted and their areas determined. EF was calculated from raw area measurements and after conversion to volume. Comparison with RVEF measured by first-pass radionuclide angiography yielded the following correlation coefficients: 4-chamber RV area, r = 0.79; parasternal short-axis RV area, r = 0.59; ellipsoid approximation RV volume, r = 0.84; pyramidal RV volume, r = 0.79; and Simpsons rule triangular cylinder RV volume, r = 0.62. Digital subtraction contrast echocardiography is a new method that can be used for semiautomated determination of RVEF. Further studies to assess the clinical values of digital image processing of 2-D echocardiograms to measure RV function appear warranted.

Cardiovascular Ochronosis: A Case Report and Review of the Medical Literature

Ochronosis is a rare disorder of tyrosine metabolism due to a deficiency of the enzyme homogentisic acid oxidase. The most common clinical manifestations include alkaptonuria, spondyloarthropathy, large joint arthritides and pigmentation of cartilage. Cardiac involvement may occur due to the deposition of polymerized homogentisic acid in the aortic, mitral and pulmonic valves. Usually, this leads to increasing rigidity and calcification. The only functionally significant valve lesion reported appears to be aortic stenosis. A possible link between ochronosis and coronary artery disease has been postulated. Further, a link between peripheral vascular disease and ochronosis may be present. We describe a case of ochronotic cardiovascular disease and review the literature on the subject.

Comparison of ST segment depression in upright treadmill and supine bicycle exercise testing

Significant differences in the hemodynamic response to upright and supine exercise have been reported in patients with coronary artery disease. The purpose of the present study was to compare the degree of myocardial ischemia as assessed by ST segment depression during upright treadmill and supine bicycle exercise in 98 patients with coronary artery disease and in 34 patients with normal coronary arteries. The amount of ST segment depression at maximal exercise in patients with coronary artery disease was 0.90 +/- 0.80 mm for treadmill and 1.34 +/- 1.09 mm for supine bicycle (p less than 0.001). The amount of ST segment depression during treadmill and supine bicycle exercise tests was also compared at highest similar heart rates (0.68 +/- 0.77 versus 1.17 +/- 1.01, p less than 0.001), at highest similar rate-pressure products (0.71 +/- 0.77 versus 1.08 +/- 1.04, p less than 0.001), at highest similar metabolic equivalents of oxygen consumption (MET) levels (0.69 +/- 0.75 versus 1.20 +/- 1.05 mm, p less than 0.001) and at the onset of angina (0.84 +/- 0.73 versus 1.18 +/- 0.88 mm, p less than 0.001). The rate-pressure product achieved at maximal exercise was similar in both tests (18.74 +/- 5.80 x 10(3) versus 18.81 +/- 5.17 x 10(3), p = NS). The occurrence of angina during treadmill and supine bicycle exercise tests was similar (47 of 98 versus 48 of 98, respectively, p = NS). For the detection of coronary artery disease, the sensitivity was 50.0% for treadmill and 63.3% for supine bicycle (p less than 0.05) and the specificity was 73.5 versus 70.6%, respectively (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetes mellitus and arteriographically - documented coronary artery disease.

Diabetics are at increased risk for coronary heart disease even after accounting for other risk factors, and the impact of diabetes mellitus may be particularly strong among females and at adverse levels of other risk factors. Therefore, the independent relation of diabetes to arteriographically-documented coronary artery disease (CAD) was examined in 5620 patients (18% female) referred to two Milwaukee hospitals from 1972 to 1986. As assessed by questionnaire, the prevalence of diabetes mellitus among these patients was 8% (n = 466). Diabetics had increased CAD (assessed by the number and severity of stenoses) even after accounting for levels of total and high-density lipoprotein cholesterol, triglycerides, hypertension, obesity, smoking, and alcohol consumption. In addition, regression analyses indicated that as compared with nondiabetics, female diabetics tended to have a greater increase in CAD than did male diabetics (p = 0.06 for sex x diabetes interaction). Although adverse levels of other risk factors did not increase the association between diabetes and CAD, female diabetics who were using oral hypoglycemics or insulin showed almost a two-fold increase in CAD severity (p less than 0.01). Results suggest that the higher relative risk of coronary heart disease among female (vs male) diabetics may be due to a proportionately greater increase in atherosclerosis.

Sequential Monotherapy of Hypertension

In most cases, the antihypertensive therapy for an individual patient is selected through a process of trial and error. This study determined if, by treating each hypertensive patient sequentially, with six antihypertensive drugs, one from each of the major classes, one could decide on the best possible drug for control of hypertension. In a randomized open‐label crossover study, 19 patients (16 male and 3 female), 28–70 years of age with a sitting diastolic blood pressure of 95–110 mm Hg were given atenolol, captopril, clonidine, indapamide, prazosin, and verapamil in a sequential manner. Each drug was started at the minimum recommended or lower dose and titrated upwards every 2 weeks, if well tolerated, until blood pressure was controlled (diastolic BP <90 mm Hg). If blood pressure was controlled, the drug was continued for another 2 weeks. A washout period of at least 2 weeks was allowed between drugs. Both systolic and diastolic blood pressures were reduced significantly with all of the six drugs. In 18 of the 19 patients, blood pressure was controlled with at least one of six drugs, frequently with the lowest dose. The authors conclude that if hypertension is not controlled with the lowest recommended dose of a drug, other antihypertensive drugs should be tried sequentially rather than increasing the dose or adding a second drug.

Refractory coronary artery spasm

A patient with an episode of refractory myocardial ischemia induced by ergonovine is described. The patient underwent cardiac catheterization 2 weeks after an inferior wall myocardial infarction for evaluation of recurrent rest angina. He developed severe spasm of the proximal right coronary artery in response to ergonovine which was partially relieved with nitrates and calcium channel antagonists. However, myocardial ischemia persisted, culminating in a new inferior wall infarction. The possible mechanism of continuing intense ischemia despite partial relief of the proximal right coronary spasm is discussed. It is suggested that ergonovine testing should perhaps be avoided during the early postinfarction period. Furthermore, if an ergonovine test is anticipated, beta-adrenergic blocking agents should be withheld.

Improved computerized quantitation of TI-201 myocardial scintigrams by combining two views.

An improved computerized procedure involving minimal operator intervention has been developed for the automated quantitative evaluation of circumferential profiles of TI-201 myocardial perfusion scintigrams to diagnose coronary artery disease. The optimal criteria for evaluating the profiles of the left anterior oblique and anterior views have been empirically determined for both immediate and delayed scintigrams. Information from both views is combined to determine values for sensitivity and specificity. In this study, 29 patients underwent both TI-201 scintigraphy and contrast coronary angiography. The computerized quantitative procedure to interpret TI-201 scintigrams was tested against the results of coronary angiography. The values of 95% for sensitivity and 100% for specificity compare well with the results of other methods and are free of most of the variables associated with visual interpretation or operator intervention on the computer.

Haemophilus parainfluenzae mitral valve vegetation without hemodynamic abnormality: Demonstration by angiography and serial echocardiography

The occurrence of Haemophilus parainfluenzae endocarditis on a previously normal mitral valve of a drug addict is described. A large mitral valve vegetation was demonstrated by serial echocardiography and cineangiography. The vegetation did not produce hemodynamic abnormalities preventing detection by physical examination. Multiple septic emboli to various organs, including brain, resulted in death. The role of serial echocardiography and the levophase of right heart cineangiography in detecting mitral valve vegetation in a patient suspected of having infective endocarditis is emphasized.

Computerized quantitation of regional myocardial perfusion in man

A computerized procedure has been developed for the generation, graphic presentation and quantitative evaluation of circumferential profiles of thallium-201 myocardial perfusion. The computer data are first filtered using a two-dimensional fast Fourier transform. The optimum criteria for evaluating the profiles of the left anterior oblique (LAO) view have been empirically determined for both rest and stress. The sensitivity of 89 percent and specificity of 75 percent compare well with the results of other methods and are free of the variables of visual interpretation.