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Biomedical subjects

J Maddahi

Publications and source records attributed to J Maddahi.

At least 91 records · Page 5Linked to original sources
PubMed1986

Noninvasive identification of left main and triple vessel coronary artery disease: improved accuracy using quantitative analysis of regional myocardial stress distribution and washout of thallium-201.

The capabilities of visual and quantitative analysis of stress redistribution thallium-201 scintigrams, exercise electrocardiography and exercise blood pressure response were compared for correct identification of extensive coronary disease, defined as left main or triple vessel coronary artery disease, or both (50% or more luminal diameter coronary narrowing), in 105 consecutive patients with suspected coronary artery disease. Extensive disease was present in 56 patients and the remaining 49 had either less extensive coronary artery disease (n = 34) or normal coronary arteriograms (n = 15). Although exercise blood pressure response, exercise electrocardiography and visual thallium-201 analysis were highly specific (98, 88 and 96%, respectively), they were insensitive for identification of patients with extensive disease (14, 45 and 16%, respectively). Quantitative thallium-201 analysis significantly improved the sensitivity of visual thallium-201 analysis for identification of patients with extensive disease (from 16 to 63%, p less than 0.001) without a significant loss of specificity (96 versus 86%, p = NS). Eighteen (64%) of the 28 patients who were misclassified by visual analysis as having less extensive disease were correctly classified as having extensive disease by virtue of quantitative analysis of regional myocardial thallium-201 washout. When the results of quantitative thallium-201 analysis were combined with those of blood pressure and electrocardiographic response to exercise, the sensitivity and specificity for identification of patients with extensive disease was 86 and 76%, respectively, and the highest overall accuracy (0.82) was obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Reverse redistribution of thallium-201: a sign of nontransmural myocardial infarction with patency of the infarct-related coronary artery.

The pattern of reverse redistribution on the day 10 poststreptokinase resting thallium-201 myocardial scintigrams is a common finding in patients who have undergone streptokinase therapy in evolving myocardial infarction. To investigate this phenomenon, 67 patients who underwent streptokinase therapy were studied pre- and 10 days poststreptokinase therapy resting thallium-201 studies, poststreptokinase therapy resting radionuclide ventriculography and coronary arteriography (60 of the 67 patients). Of the 67 patients, 50 (75%) showed the reverse redistribution pattern on the day 10 thallium-201 study (Group I), 9 (13%) had a nonreversible defect (Group II) and the remaining 8 (12%) had a normal study or showed a reversible defect (Group III). The reverse redistribution pattern was associated with patency of the infarct-related artery (100%), quantitative improvement in resting thallium-201 defect size from day 1 to day 10 study (94%) and normal or near normal wall motion on day 10 radionuclide ventriculography (80% of segments with marked and 54% of those with mild reverse redistribution). In contrast, nonreversible defects were associated with significantly less frequent patency of the infarct-related artery (67%, p = 0.01), improvement in defect size (11%, p less than 0.001) and normal or near normal wall motion (21%, p less than 0.05). Group III patients were similar to Group I with respect to these variables. The quantitated thallium-201 percent washout was higher in the regions with the reverse redistribution pattern (49 +/- 15%) compared with the contralateral normal zone (24 +/- 15%, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Quantification of myocardial infarct size by thallium-201 single-photon emission computed tomography: experimental validation in the dog.

To evaluate the potential advantages of thallium-201 (201T1) single-photon emission computerized tomography (SPECT) to assess myocardial infarct size in the experimental animal, six normal dogs and 14 dogs with 6 to 8 hr closed-chest coronary occlusion (eight left anterior descending and six left circumflex) were studied. Ten minutes after intravenous administration of 2 mCi of 201T1, 30 projections were obtained over 180 degrees. The dogs were killed and their hearts sliced and stained by triphenyl tetrazolium chloride (TTC). Pathologic infarct size was calculated for each slice and for the entire left ventricular myocardium as percent weight. Tomograms were quantified by automatically generating maximum-count circumferential profiles, which were compared with normal limit profiles derived from the six normal dogs. Tomographic infarct size was defined as the percentage of circumferential points falling below normal for each tomogram. SPECT and TTC infarct size on 71 slices correlated highly (mean +/- SD 27.9 +/- 23.4% and 26.7 +/- 25.3%, respectively; r = .93, p less than .001, SEE = 9.4%). To determine SPECT infarct size as percent total left ventricular myocardial weight, infarct sizes from each slice were added to one another after each was multiplied by a coefficient that reflected the contribution of that slice to the total left ventricular weight. SPECT and TTC infarct size for the entire left ventricle correlated closely (mean +/- SD 20.5 +/- 7.6% and 19.3 +/- 8.3%, respectively; r = .86, p less than .001, SEE = 4.5%). It is concluded that 201T1 SPECT is a valid method for the noninvasive assessment of experimental myocardial infarct size.

Animals↗
PubMed1986

Quantitation of extent, depth, and severity of planar thallium defects in patients undergoing exercise thallium-201 scintigraphy.

Previous quantitation of exercise-redistribution planar 201TI scintigraphy has shown high sensitivity and specificity in the detection of coronary artery disease and improved detection of individual coronary stenoses over visual analysis. By using similar methodology based on the circumferential profile method, we studied 133 patients to quantitatively assess the extent, depth, and severity of thallium defects compared with consensus visual analysis. These quantitative measurements are objective, requiring only three operator interactions. In comparing quantitative and visual results, a close correlation was found for measurement of extent of thallium defect (r = 0.73) and severity of defect (r = 0.79). In detecting patients with the high-risk scintigraphic pattern of a severe stress thallium defect, a quantitative depth score of greater than or equal to 36 had an 81% sensitivity and an 82% specificity. Thus, this nearly automatic, computerized quantitative method allows objective determination of extent, severity, and depth of planar 201TI defects.

Aged↗
PubMed1985

Factors that determine the direction and magnitude of precordial ST-segment deviations during inferior wall acute myocardial infarction.

Sixty-one patients with inferior acute myocardial infarction (AMI) and no evidence of prior AMI were studied to determine which factors influence the magnitude of precordial ST-segment depression. In the total study group, there was a significant but weak correlation between the magnitude of precordial ST-segment depression and the magnitude of inferior ST-segment elevation (r = -0.46, p less than 0.001). In the 29 patients with evidence of concomitant right ventricular (RV) involvement, precordial ST-segment depression was significantly smaller both in absolute terms (-1.3 +/- 1.8 vs -2.8 +/- 1.9 mm, p less than 0.01) and relative to the magnitude of inferior ST-segment elevation (ratio of -0.2 +/- 1.0 vs -1.1 +/- 0.5, p less than 0.01), whereas in the 15 patients with lateral ST-segment elevation (greater than or equal to 1 mm in lead V6), precordial ST-segment depression was significantly greater both in absolute terms (-3.5 +/- 2.3 vs -1.6 +/- 1.7 mm, p less than 0.01) and relative to the magnitude of inferior ST-segment elevation (ratio of -1.1 +/- 0.8 vs -0.5 +/- 0.9, p less than 0.02). Consistent with these findings, the correlation between the magnitudes of precordial and inferior ST-segment deviations was considerably improved when only the 24 patients with neither evidence of RV involvement nor lateral ST-segment elevation were analyzed (r = 0.89, p less than 0.001, n = 24). These data suggest that in patients with inferior AMI, there is a reciprocal relation between precordial and inferior ST-segment deviations, which is distorted by concomitant RV involvement and by concomitant lateral left ventricular wall involvement.

Aged↗
PubMed1985

Left ventricular performance in septic shock: reversible segmental and global abnormalities.

Left ventricular dysfunction has been implicated in the pathogenesis of septic shock, but little is known about its natural history, cause, and prognostic significance. Left ventricular performance was assessed by serial radionuclide and hemodynamic studies in 35 patients with culture-proven septic shock. The mean age (+/- S.D.) of the group was 64 +/- 18 years; 16 of the subjects were women, and 15 had antecedent heart disease. On the first study, the left ventricular stroke work index was depressed in 33 (94%) patients, and nineteen (54%) had a left ventricular ejection fraction less than 0.48. Twenty-two (63%) of the patients had segmental and four had generalized wall motion abnormalities. Conventional hemodynamic parameters were of no value in predicting the patients who had a depressed left ventricular ejection fraction or segmental abnormalities. Patients with underlying heart disease had a much higher frequency (87%) of segmental dysfunction than those without underlying heart disease (45%; p = 0.016), but no differences were noted in the left ventricular ejection fraction or left ventricular stroke work index of these two groups. Segmental abnormalities and low ejection fractions were seen more often in patients with a large left ventricular end-diastolic volume index. Only five subjects had a systemic vascular resistance index greater than 2580 dynes X sec X cm-5 per m2, and the correlation between systemic vascular resistance index and left ventricular ejection fraction was poor. No difference was found in the mean coronary perfusion pressure of those with segmental abnormalities and those with normal wall motion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Thallium-201 stress-redistribution myocardial rotational tomography: development of criteria for visual interpretation.

Despite high sensitivity and specificity for overall detection of coronary artery disease (CAD), planar stress-redistribution thallium-201 (Tl-201) scintigraphy remains suboptimal in localizing disease, because of overlap of myocardial segments. Single photon emission computerized tomography (SPECT), by providing three-dimensional representation of myocardial Tl-201, offers promise for improved localization of CAD. In 50 consecutive patients (22 normal and 28 with CAD), who underwent SPECT stress-redistribution Tl-201 imaging, we systemically developed visual interpretive criteria for perfusion abnormality on SPECT. For overall detection of disease, the best criterion for abnormality was greater than or equal to 8 sectors of moderately decreased Tl-201 uptake. With this criterion, the true positive and true negative rates for overall detection of disease were 96% and 91%, respectively. The best criterion for significant defect in the anterior or posterior coronary circulation was greater than or equal to 3 sectors of moderately decreased Tl-201 uptake. With this criterion, the true positive and true negative rates for anterior circulation disease were 71% and 100%, respectively. With respect to posterior circulation disease, the true positive and true negative rates were 100% and 50%, respectively. Regarding identification of dual circulation disease, the true positive and true negative rates were 71% and 82%, respectively.

Adult↗
PubMed1985

Precordial ST segment depression during acute inferior myocardial infarction: early thallium-201 scintigraphic evidence of adjacent posterolateral or inferoseptal involvement.

To investigate the myocardial perfusion correlates of precordial ST segment depression during acute inferior myocardial infarction, a rest thallium-201 scintigram and a closely timed 12 lead electrocardiogram were obtained within 6 hours of the onset of infarction in 44 patients admitted with their first acute inferior myocardial infarction. Thirty-six patients demonstrated precordial ST segment depression (group 1) and eight did not (group 2). A perfusion defect involving the inferior wall was present in all 44 patients. Additional perfusion defects of the adjacent posterolateral wall (n = 20), the ventricular septum (n = 9) or both (n = 6) were present in 35 of 36 patients from group 1 compared with only 1 of 8 patients from group 2 (p less than 0.001). There was no significant difference in the frequency of multivessel coronary artery disease or disease of the left anterior descending artery between group 1 and group 2 or between patients with and those without a thallium-201 perfusion defect involving the ventricular septum. Thus, precordial ST segment depression during an acute inferior myocardial infarction is associated with thallium-201 scintigraphic evidence of more extensive involvement of the adjacent posterolateral or inferoseptal myocardial segments, which probably reflects the extent and pattern of distribution of the artery of infarction, rather than the presence of coexistent multivessel coronary artery disease or disease of the left anterior descending artery.

Aged↗
PubMed1985

Scintigraphically detected predominant right ventricular dysfunction in acute myocardial infarction: clinical and hemodynamic correlates and implications for therapy and prognosis.

To determine the clinical and hemodynamic correlates as well as therapeutic and prognostic implications of predominant right ventricular dysfunction complicating acute myocardial infarction, 43 consecutive patients with scintigraphic evidence of right ventricular dyssynergy and a depressed right ventricular ejection fraction (less than 0.39) in association with normal or near normal left ventricular ejection fraction (greater than or equal to 0.45) were prospectively evaluated. All 43 patients had acute inferior infarction, forming 40% of patients with acute inferior infarction, and only eight (24%) had elevated jugular venous pressure on admission. On hemodynamic monitoring, 74% of patients had a depressed cardiac index (less than or equal to 2.5 liters/min per m2), averaging 2.0 +/- 0.05 for the group. Of these, 30% did not demonstrate previously described hemodynamic criteria of predominant right ventricular infarction (right atrial pressure greater than or equal to 10 mm Hg or right atrial to pulmonary capillary wedge pressure ratio greater than or equal to 0.8, or both). The left ventricular end-diastolic volume was reduced to 49 +/- 11 ml/m2 (n = 22) and correlated significantly with the stroke volume index (r = 0.82; p less than 0.0001) and cardiac index (r = 0.57; p = 0.005). The follow-up right ventricular ejection fraction, determined in 33 patients, showed an increase of 10% or greater in 26 (79%), increasing from a mean value of 0.30 +/- 0.06 to 0.40 +/- 0.09 (p less than 0.0001) without a significant overall change in the mean left ventricular ejection fraction (0.56 +/- 0.10 to 0.56 +/- 0.11, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1985

Reversal of rest myocardial asynergy during exercise: a radionuclide scintigraphic study.

UNLABELLED: While exercise-induced segmental left ventricular wall motion abnormalities are well described, the phenomenon of improvement in certain asynergic segments during exercise in some patients remains a curiosity. To assess this unexpected finding, results were analyzed in 85 patients with wall motion abnormalities at rest who underwent two view (45 degrees left anterior oblique and anterior) exercise radionuclide ventriculography and exercise thallium-201 myocardial perfusion imaging. Wall motion was scored with a 5 point system (from 3 [normal] to - 1 [dyskinesia]); normalization or increase of 2 or more points with exercise signified improvement. Forty-eight patients (56%) had no change or further deterioration of wall motion at peak exercise, 15 (18%) showed both improvement of wall motion and deterioration and 22 (26%) showed only improvement of wall motion. Wall motion improvement during exercise was found in 57 (20%) of 279 segments with asynergy at rest. Of these 57 segments improving with exercise, 45 (79%) showed mild and 12 (21%) showed severe asynergy at rest. Only seven segments (12%) were associated with pathologic Q waves. Thallium-201 perfusion was normal in 44 segments (77%) while only 6 segments (11%) had reversible and only 7 (12%) had nonreversible thallium-201 defects. IN CONCLUSION: 1) wall motion that is abnormal at rest can sometimes improve with exercise; 2) this phenomenon generally occurs in zones without a Q wave or nonreversible thallium-201 defect. Hence, segments with abnormal wall motion at rest that show improvement with exercise appear to represent viable nonischemic segments.

Adult↗
PubMed1985

Slow regional clearance of myocardial thallium-201 in the absence of perfusion defect: contribution to detection of individual coronary artery stenoses and mechanism for occurrence.

As a result of the "spatially relative" nature of perfusion defect analysis of stress-redistribution thallium-201 (201Tl) scintigrams, hypoperfused myocardial segments may not appear as perfusion defects but they may demonstrate a slow washout rate of 201Tl that can be analyzed in a "spatially nonrelative" manner. Quantitative analysis of perfusion defects and slow washout rate of 201Tl was performed on scintigrams from 116 consecutive patients with adequate exercise tests, defined as achievement of 85% or more of age-predicted maximum heart rate or development of angina or ST segment depression. A total of 232 diseased and 116 nondiseased vessels were found in the patients. Additional analysis of slow washout rate significantly (p less than .05) improved sensitivity for detection of disease in the left anterior descending (from 74% to 82%), left circumflex (from 40% to 61%), and right coronary arteries (from 78% to 90%) without significant loss of specificity. This improvement resulted from the additional detection of 32 of 232 (14%) diseased vascular distributions when the isolated slow washout rate of 201Tl was also determined. In nine of these 32, isolated slow washout rate was associated with another region with isolated slow washout rate in the contralateral myocardial segment. Coronary arteriography revealed similar degrees of stenosis in the vessels supplying these segment pairs. In 13 of 32 cases, a perfusion defect and a slow washout rate were found in the contralateral segment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Quantification of rotational thallium-201 myocardial tomography.

A comprehensive method is described for quantification of the relative 3-dimensional distribution of Tl-201 in the myocardium, following stress and subsequent washout. The method uses maximal-count circumferential profiles of well-defined long- and short-axis tomograms to determine the 3-dimensional distribution of Tl-201; it then maps this distribution onto a 2-dimensional polar representation. Abnormal thallium distribution or washout is identified by automatic computer comparison of each patient's profile with the corresponding lower limits of normal profiles. Abnormality is expressed as a percentage of the entire myocardium by use of polar maps for extent and severity. The binary extent map expresses the degree of abnormality. Preliminary criteria for abnormality were derived from the tomographic results of 25 normals and 28 patients with documented coronary artery disease. The results were normal in 23 of the 25 normals and were abnormal in 25 of the 28 CAD patients. In addition, the computer output correctly localized the presence or absence of disease in 46 of 56 coronary circulations.

Adult↗
PubMed1984

Intravenous streptokinase in evolving acute myocardial infarction.

Eighty-one consecutive patients presenting within 3 hours of the onset of acute myocardial infarction (AMI) and without contraindications to thrombolytic or anticoagulant therapy received a 15- to 30-minute intravenous infusion of 750,000 or 1.5 million units of streptokinase (STK) followed by anticoagulation. Treatment was instituted 130 +/- 41 minutes after the onset of symptoms and reperfusion was achieved 36 +/- 26 minutes later. Reperfusion of the "infarct artery" was recognized by indirect clinical criteria in 78 patients (96%). In all 66 patients who underwent coronary angiography 3 to 7 days later, there was complete concordance between indirect and angiographic evidence of reperfusion. In 6 patients there was early reocclusion within 24 hours of treatment; in 4 of these patients, the artery was reopened with an additional dose of STK. Two elderly patients suffered an intracranial hemorrhage and there were 8 other major hemorrhagic complications, of which 7 were related to procedural trauma. Five patients (6.2%) died in the hospital. The results of intravenous STK thrombolytic therapy are compared with those of our previous study using intracoronary STK.

Aged↗
PubMed1984

ST elevations in leads V1 to V5 may be caused by right coronary artery occlusion and acute right ventricular infarction.

In 5 of 69 patients (7%) undergoing intracoronary or intravenous streptokinase treatment, the ST-segment elevations in leads V1 to V5 were caused by occlusion of the right rather than the left anterior descending coronary artery and by myocardial infarction (MI) of the right ventricular (RV) wall rather than the anterior left ventricular (LV) wall or the ventricular septum. RV involvement was documented by technetium pyrophosphate uptake, hypokinesia, dilatation and depressed RV ejection fraction. The left anterior descending artery was patent and the anterior LV wall had normal thallium-201 uptake, no technetium uptake and normal wall motion. ST-segment elevation was highest in lead V1 or V2 and decreased toward lead V5; in patients with anterior LV MI, the ST-segment elevations are usually lowest in lead V1 and increase toward the V5 lead. In contrast to anterior LV infarcts, the R waves in leads V1 to V5 did not decrease and Q waves did not evolve with progression of the MI. The ST-segment elevations in leads V1 to V5 in our patients were associated with small or absent ST-segment elevations in leads, II, III and aVF, suggesting that in other cases of RV infarction, the appearance of ST-segment elevations in leads V1 to V5 is blocked by the dominant electrical forces of the LV inferior MI. This suggestion was confirmed in a canine model. Recognition of the presence of RV infarction may be therapeutically important.

Adult↗
PubMed1984

Diffuse slow washout of myocardial thallium-201: a new scintigraphic indicator of extensive coronary artery disease.

When coronary artery disease is extensive and of relatively uniform severity, regional myocardial hypoperfusion may be balanced during stress, precluding development of spatially relative perfusion defects. Assessment of the washout of thallium-201 from myocardial regions may provide diagnostic assistance in these cases because washout analysis is spatially nonrelative and hypoperfused myocardial regions manifest a slow thallium-201 washout rate. In 1,265 consecutive patients having quantitatively analyzed stress-redistribution scintigraphy, 46 had a diffuse slow washout pattern with no or a maximum of one regional perfusion defect. Thirty-two underwent clinically indicated coronary angiography, and 23 (72%) of these were found to have three vessel or left main disease. Of 30 similar patients without a diffuse slow washout pattern and with no or a maximum of one perfusion defect, only 5 (17%) had extensive coronary disease. An independent relation between diffuse slow washout and extensive coronary disease was demonstrated by a Mantel- Haentzel chi-square analysis of a wide variety of other indexes of extensive disease. A diffuse washout abnormality, even in the absence of other scintigraphic, clinical or electrocardiographic indicators, carries a high predictive value for three vessel or left main coronary artery disease. The predictive value is maintained when the exercise level achieved is submaximal. Although an infrequent occurrence (3.6% of tested patients), a diffuse slow washout pattern without other scintigraphic indications of extensive coronary disease should lead to further diagnostic testing.

Coronary Angiography↗
PubMed1983

Enhanced detection of proximal right coronary artery stenosis with the additional analysis of right ventricular thallium-201 uptake in stress scintigrams.

The value of right ventricular thallium-201 analysis in detecting proximal right coronary artery stenosis in exercise myocardial scintigraphy was analyzed in 52 patients, 27 with and 25 without proximal right coronary artery stenosis. For the detection of proximal right coronary artery stenosis, the sensitivity and specificity of thallium scintigraphic analysis were 59 and 88% for a right ventricular abnormality, 67 and 68% for a left ventricular inferior wall abnormality, and 93 and 56% for an abnormality of either. When both right and left ventricular thallium images were abnormal, all 9 patients had proximal right coronary artery stenoses, and when both were normal, 26 of 28 patients had a normal proximal right coronary artery. The sensitivity and specificity of blood pool scintigraphic variables during exercise (right ventricular ejection fraction and left ventricular inferior wall motion) were not significantly different for detection of proximal right coronary artery stenosis. Thus, the additional analysis of the right ventricle on thallium-201 stress scintigrams can improve the detection of proximal right coronary artery stenosis. When both right ventricular and left ventricular thallium scintigrams are abnormal (or normal), the ability to predict the presence (or absence) of proximal right coronary artery stenosis is very high.

Adult↗