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Biomedical subjects

D S Berman

Publications and source records attributed to D S Berman.

At least 163 records · Page 9Linked to original sources
PubMed1987

Experimental evaluation of technetium-99m red blood cell radionuclide ventriculography for detecting pericardial bleeding.

Abnormal loculated or diffuse blood pools adjacent to the heart have been observed in patients with pericardial bleeding who have been imaged by gated equilibrium radionuclide ventriculography (RNV). To study the scintigraphic appearance of fresh pericardial blood, we performed equilibrium RNV in six dogs with measured volumes (10, 30, or 50 ml) of intrapericardial blood. Loculated and diffuse pericardial blood was simulated by injecting the blood either into an intrapericardial balloon, or freely into the pericardial space. Ability to detect pericardial blood was determined by blinded review, and blood volume analysis was attempted by measuring its scintigraphic thickness, brightness (relative to the left ventricle), extent, and background-subtracted count rate and a peak count index. Detection rates for 10, 30, and 50 ml were all 100% for loculated pericardial blood, and 67%, 100% and 100% for free pericardial blood, with the use of three scintigraphic views. Visually determined "extent" of the abnormal blood pool was the most reliable indicator of pericardial blood volume. When the volume was 30 ml or more, at least 40% of the heart was surrounded in 26 of 27 cases (96%); the specificity of this finding was 90%. We conclude from this animal study that RNV should be a sensitive method for detecting pericardial bleeding; visual appearance permits qualitative assessment of the volume of accumulated labeled blood.

Animals↗
PubMed1987

Differences in the frequency of ST segment depression during upright and supine exercise: assessment in normals and in patients with coronary artery disease.

Increased utilization of ambulatory ST segment monitoring mandates an appreciation of nonischemic variables that may influence the ST segment. While a greater frequency of ST segment depression has been reported with supine vs upright exercise, the relative false positive rate in both positions is not known. Thus, we compared the frequency of exercise ECG abnormalities during upright and supine bicycle exercise in two groups--17 normals and 46 patients with coronary artery disease. Exercise was performed in combination with radionuclide ventriculographic imaging. Peak exercise heart rate, peak systolic blood pressure, and exercise duration time were all slightly higher in the upright vs supine position (p less than 0.05). Nevertheless, the frequency of positive ST segment responses was more common in the supine position, both in the patients with coronary artery disease (54% vs 30%, p less than 0.05) and in the normal subjects (29% vs 6%, p = NS). The corresponding radionuclide ventriculographic responses, however, were normal during upright and supine exercise in 6 of the 11 CAD patients and in all five of the normal subjects with an abnormal ST segment response during supine exercise only. The frequency of exercise-induced chest pain was also similar in the two positions. Thus, we theorize that nonischemic factors may govern some positive ST segment responses in the supine position. This finding is of relevance for understanding the potential sources of physiologic false positive ST segment responses for ambulatory ST segment monitoring.

Adult↗
PubMed1987

Silent myocardial ischemia: II. Prognosis and implications for the clinical assessment of patients with coronary artery disease.

Myocardial ischemia is known to be a strong independent predictor of cardiac events. New data suggest that the presence of silent ischemia, like symptomatic ischemia, is indicative of an increased risk of future cardiac events. Ordinarily, patients with suspected or known coronary artery disease are evaluated first for the presence of myocardial ischemia by performing exercise ECG, used as a test of both diagnosis and prognosis. In those patients who have an "intermediate" probability of cardiac event after exercise ECG, prognostic assessment may be enhanced, by using either radionuclide stress testing, to assess the extent and severity of potentially inducible ischemia, or ambulatory ECG, to assess the frequency and duration of spontaneously occurring ischemia. The indications for testing and type of test to be used are highly dependent on a number of clinical factors, not the least of which are the nature of the population to be evaluated and the exercise ECG response. We have proposed an overall approach for prognostic testing that considers the potential strengths and limitations of each form of testing. This potential approach now requires prospective evaluation.

Ambulatory Care↗
PubMed1987

The clinical significance of exercise-induced left ventricular wall motion abnormality occurring at a low heart rate.

We studied the relationship between the heart rate at the time of onset of exercise-induced wall motion abnormality and the severity of coronary artery disease in 89 patients who underwent exercise equilibrium radionuclide ventriculography as part of their evaluation for coronary artery disease. Segmental wall motion was scored with a five-point system (3 = normal; -1 = dyskinesis); a decrease of one score defined the onset of wall motion abnormality. The onset of wall motion abnormality at less than or equal to 70% of maximal predicted heart rate had 100% predictive accuracy for coronary artery disease and higher sensitivity than the onset of ischemic ST segment depression at similar heart rate during exercise: 36% (25 of 69 patients with coronary disease) vs 19% (13 of 69 patients), p = 0.01. Wall motion abnormality occurring at less than or equal to 70% of maximal predicted heart rate was present in 49% of patients (23 of 47) with critical stenosis (greater than or equal to 90% luminal diameter narrowing), and in only 5% of patients (2 of 42) without such severe stenosis, p less than 0.001. The sensitivity of exercise-induced wall motion abnormality occurring at a low heart rate for the presence of severe coronary artery disease was similar to that of a deterioration in wall motion by more than two scores during exercise (49% vs 53%) or an absolute decrease of greater than or equal to 5% in exercise left ventricular ejection fraction (49% vs 45%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

The efficacy of cardiovascular nuclear medicine exercise studies.

Radionuclide stress tests were initially introduced into medicine as new diagnostic tests for coronary artery disease (CAD). These tests are very effective for this purpose when applied to populations with an intermediate pre-test probability of coronary artery disease. Radionuclide stress tests, however, also are used now in guiding many management decisions in patients with established CAD, based on the ability of these tests to assess the extent and severity of myocardial ischemia, the functional significance of coronary stenoses, and myocardial viability. Specific uses beyond diagnosis include decisions regarding whom to catheterize, send to coronary bypass surgery, or angioplasty; risk stratification following myocardial infarction or before noncardiac surgery; and evaluation of the results of therapy. This article reviews both the diagnostic efficacy of radionuclide stress tests and their efficacy in guiding management decisions in patients with known coronary artery disease.

Cardiovascular System↗
PubMed1987

Noninvasive quantification of left ventricular myocardial mass by gated proton nuclear magnetic resonance imaging.

The validity of cardiac nuclear magnetic resonance imaging for determination of left ventricular myocardial mass was evaluated in nine dogs. A gated spin echo-pulsing sequence was used for in vivo imaging, obtaining 0.7 cm thick slices of the heart spaced by 1 cm. On each imaged slice, the left ventricular surface area was reproducibly determined by planimetry and was multiplied by slice spacing and specific gravity of the myocardium (1.05) to obtain slice mass. Total left ventricular mass was calculated by adding slice masses in short-axis (method I), transaxial (method II) and vertical long-axis (method III) orientations using Simpson's rule. With each method, masses of the portions of the left ventricle subject to partial volume effect either were not accounted for or alternatively were estimated from the same or an orthogonal imaging plane. Calculated left ventricular mass was compared with the actual excised left ventricular weight. With NMR imaging of in situ nonbeating hearts, best results were obtained when either method I or method II was used and partial volume effect was estimated either from the same or an orthogonal plane. With in vivo NMR imaging, best results were noted when method I was used and mass of the partial volume apex was calculated from transaxial slices: Y (in vivo NMR image) = 8.3 + 0.99X, r = 0.996, SEE = 3.14. For this method, the interobserver reliability coefficient and standard error of the measurement were 0.97 and 5.4, respectively. Compared with method I, in vivo methods II and III were associated with larger errors (SEE ranging from 13.03 to 19.03) regardless of the approach used to estimate partial volume effect. It is concluded that NMR imaging is a highly accurate noninvasive method for in vivo measurement of left ventricular mass in dogs and offers promise for accurate measurement of left ventricular mass in patients.

Animals↗
PubMed1987

Transient ischemic dilation of the left ventricle on stress thallium-201 scintigraphy: a marker of severe and extensive coronary artery disease.

On exercise thallium-201 scintigraphy, it has been noted that the size of the left ventricle is sometimes larger on the immediate poststress image than on the 4 hour redistribution image; this phenomenon has been termed transient ischemic dilation of the left ventricle. The angiographic correlates of this finding were assessed in 89 consecutive patients who underwent both stress-redistribution thallium-201 scintigraphy and coronary arteriography. A transient dilation ratio was determined by dividing the computer-derived left ventricular area of the immediate postexercise anterior image by the area of the 4 hour redistribution image. In patients with a normal coronary arteriogram or nonsignificant coronary stenoses (less than 50%), the transient dilation ratio was 1.02 +/- 0.05 and, therefore, an abnormal transient dilation ratio was defined as greater than 1.12 (mean + 2SD). The transient dilation ratio was insignificantly elevated in patients with noncritical coronary artery disease (50 to 89% stenosis) (1.05 +/- 0.05) and in patients with critical stenosis (greater than or equal to 90%) of only one coronary artery (1.05 +/- 0.05). In contrast, in patients with critical stenoses in two or three vessels, the transient dilation ratio was significantly elevated (1.12 +/- 0.08 and 1.17 +/- 0.09, respectively; p less than 0.05 compared with all other patient groups). An abnormal transient dilation ratio had a sensitivity of 60% and a specificity of 95% for identifying patients with multivessel critical stenosis and was more specific (p less than 0.05) than were other known markers of severe and extensive coronary artery disease, such as the presence of multiple perfusion defects or washout abnormalities, or both.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Comprehensive noninvasive evaluation of left atrial myxomas using cardiac cine-computed tomography.

This report describes the first clinical experience with ultrafast (cine) computed tomography for evaluating intracardiac masses. Two patients had a left atrial myxoma that was comprehensively described (size, location, site of attachment and relation to the mitral valve) preoperatively by cine-computed tomography. The information content of the studies exceeded that of two-dimensional echocardiography, and both patients were operated on without invasive cardiac catheterization. This early experience with a new minimally invasive high temporal and spatial resolution technology suggests that cine-computed tomography may be uniquely suited for precise evaluation of intraatrial masses.

Female↗
PubMed1987

Prospective evaluation of ultrafast cardiac computed tomography for determination of coronary bypass graft patency.

Twenty-five consecutive patients with 68 independent (single distal anastomosis) saphenous vein aortocoronary and 12 internal mammary bypass grafts (27 to left anterior descending, 10 to diagonal, 23 to left circumflex, 20 to right coronary artery) entered a reader-blinded, prospective, standardized study to establish the accuracy of ultrafast (cine) cardiac computed tomography (CT) for determining graft patency compared with invasive angiography. All patients underwent imaging after injection of 35 to 45 ml of meglumine diatrizoate (Renografin-76; 7 to 9 ml/sec for 5 sec) into an arm vein. Electrocardiographically triggered images were acquired over eight to 16 tomographic levels at 1 cm intervals from aortic arch to mid left ventricle. Criteria for graft patency were contrast opacification on at least two noncontinguous levels and contrast density-time curves morphologically similar to that of the aorta. Ultrafast CT correctly determined that 46 of 48 bypass grafts were patent and 31 of 32 were occluded (sensitivity, specificity, and accuracy 96%, 97%, and 96%); there were no interpretation errors in 23 (92%) of the 25 patients. Accuracy was independent of vessel bypassed and not different for saphenous veins (96%) compared with internal mammary bypasses (100%). This study establishes a 20 min outpatient intravenous injection technique that is highly accurate for determining patency of coronary artery bypass grafts.

Coronary Angiography↗
PubMed1987

Comparative methods for quantifying myocardial infarct size by thallium-201 SPECT.

Maximum-count circumferential profile analysis of 201TI single photon emission computed tomograms (SPECT) was employed to quantify infarct size (15) in ten dogs with acute closed chest coronary occlusion (seven left anterior descending coronary artery and three left circumflex coronary artery) who underwent rest-redistribution 201TI SPECT. The extent of hypoperfused myocardium was calculated as a percentage of slice mass on rest-redistribution 201TI SPECT. Pathologic IS was determined by triphenyl tetrazolium chloride (TTC) staining. On each tomogram, SPECT IS was defined as the % of the maximum-count circumferential profile points falling below normal. To calculate total LV infarct size, slice ISs were added to one another after each was multiplied by a coefficient K that reflected the contribution of that slice to the total left ventricular mass. K was derived from an observed relationship in normal dogs between slice fractional distance from the apex and either its actual weight, its geometric SPECT area, or its count-based SPECT area, the assessment of which was independent of edge detection. Using any of these algorithms, there was a high linear correlation between the tomographic and TTC IS. A similar algorithm was also developed from tomograms of eight normal patients. These data offer promise for the clinical noninvasive assessment of the extent of hypoperfused myocardium.

Algorithms↗
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

Cine computed tomographic evaluation of aortocoronary bypass graft patency.

Evaluation of the patency of coronary bypass grafts has previously required hospitalization for invasive angiography. This report of three cases documents the unique capability of cardiac cine computed tomography to easily and accurately define coronary bypass graft patency. In each case, the findings altered therapeutic decisions. This early experience justifies wider application of this technique and suggests that it may eliminate the need for diagnostically motivated graft angiography. Large scale studies to establish the sensitivity and specificity of cardiac cine computed tomography for determining graft patency are indicated.

Coronary Angiography↗
PubMed1986

Should the intent of testing influence its interpretation?

A test is often interpreted as "normal" or "abnormal" by a single criterion, regardless of the intent of testing. The discriminate accuracy of this convention was critically analyzed using information content (I), likelihood ratio and the area under the receiver-operating characteristic curve. Three ejection fraction variables were assessed--ejection fraction at rest, exercise ejection fraction and the change in ejection fraction from rest to exercise--each relative to three intentional goals: diagnosis of coronary artery disease in 929 patients without previous myocardial infarction, prediction of multivessel disease in these same 929 patients and prediction of multivessel disease in 507 patients with previous myocardial infarction. The information content of exercise ejection fraction (IEX) was higher than for ejection fraction at rest (IR) or for the change from rest to exercise (IEX-R), and was relatively constant regardless of the goal of testing. In contrast, neither IR nor IEX-R was constant. IR was lowest for diagnosis of coronary artery disease, whereas IEX-R was highest for this same goal. These empiric observations are consistent with the quantitative relation predicted by information theory: IEX = IR + IEX-R. Thus, ejection fraction at rest has little discriminate value relative to the diagnosis of coronary artery disease, but does have value in evaluating the extent of disease in patients after myocardial infarction. Exercise ejection fraction and change in ejection fraction are nearly equally useful for purposes of diagnosis, whereas the former is most useful for functional evaluation in postinfarction patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗