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Biomedical subjects

J Heo

Publications and source records attributed to J Heo.

At least 127 records · Page 7Linked to original sources
PubMed1986

Ventricular systolic and diastolic impairment during pacing-induced myocardial ischemia in coronary artery disease: simultaneous hemodynamic, electrocardiographic, and radionuclide angiographic evaluation.

This study examined the impairment in systolic and diastolic performance of both ventricles during pacing-induced myocardial ischemia in 12 men with coronary artery disease. Simultaneous hemodynamic, ECG, and radionuclide angiographic assessments were made: pre pacing (pre-P); intermediate pacing (P-1); maximum pacing (P-2); and immediately after pacing (post pacing (P-P). The prepacing measurements were made with the patient in the supine position and during leg elevation. Pacing produced a leftward and upward shift in the diastolic pressure-volume relation, a progressive decrease in left ventricular (LV) end-diastolic volume (p less than 0.003) and right ventricular (RV) end-diastolic volume (p less than 0.01), concomitant with an increase in the pulmonary artery wedge pressure (p less than 0.004) and the right atrial pressure (p less than 0.04). The shift in the LV pressure-volume relation was associated with an initial increase (P-1), followed by a decrease (P-2) in the peak filling rate (p less than 0.001). Pacing also resulted in systolic dysfunction: abnormal LV ejection fraction responses in eight patients, LV regional wall motion abnormalities in eight patients, and abnormal RV ejection fraction responses in seven patients. Leg elevation resulted in a 7% increase in cardiac output, a 20% increase in RV end-diastolic volume, a 28% increase in right atrial pressure, a 29% increase in pulmonary artery wedge pressure, and a 10% increase in LV end-diastolic volume (p less than 0.05). Thus, the ischemic response to pacing results in systolic and diastolic LV and RV dysfunction, with the diastolic impairment being more frequent than the systolic impairment.

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PubMed1986

Effects of esmolol on patients with left ventricular dysfunction.

This study examined the effect of esmolol, an ultrashort-acting beta-receptor blocker, in 10 patients with severe left ventricular dysfunction. Simultaneous hemodynamic and radionuclide angiographic measurements were obtained at incremental doses of esmolol (2, 4, 8, 12 and 16 mg/min). At a dose of 4 mg/min, esmolol produced beats blockade: a decrease in heart rate from 91 +/- 4 to 83 +/- 4 beats/min (p less than 0.05) (mean +/- SEM) and a decrease in systolic aortic pressure from 133 +/- 5 to 128 +/- 5 mm Hg (p less than 0.05). At the maximal dose, the heart rate decreased to 79 +/- 3 beats/min (p less than 0.05) and biventricular function was depressed; the left ventricular ejection fraction decreased from 27 +/- 2 to 21 +/- 2% (p less than 0.05) and the right ventricular ejection fraction decreased from 38 +/- 2 to 29 +/- 2% (p less than 0.05). These changes were accompanied by increases in left ventricular end-diastolic volume (p less than 0.05), left ventricular end-systolic volume (p less than 0.05) and pulmonary artery wedge pressure (p less than 0.05), as well as a decrease in cardiac output (p less than 0.05). The hemodynamic abnormalities (which showed considerable interindividual variability) returned to near baseline levels 10 to 30 minutes after infusion was stopped. Thus, esmolol can be administered to patients with severe left ventricular dysfunction. The beneficial effect (beta-adrenergic blockade) is usually achieved with small doses without clinically important hemodynamic changes. At larger doses, however, significant changes in biventricular function may be observed.

Adrenergic beta-Antagonists↗
PubMed1986

Angina: DDx of atypical presentations in the elderly.

Pretest probability of coronary heart disease should be considered in interpreting exercise test results. In general, 90% of patients with typical angina pectoris, 50% of patients with atypical angina pectoris, and only 10% of patients with nonanginal chest pains have CHD. Marked ST-segment depression in multiple leads is a good indication of extensive coronary artery disease, especially when it occurs early during exercise or at submaximal exercise, and if associated with a blunted or a hypotensive BP response.

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PubMedDate not supplied

Planar and tomographic imaging with technetium 99m-labeled tetrofosmin: correlation with thallium 201 and coronary angiography.

This study compared the results of planar and single-photon emission computed tomographic (SPECT) imaging with tetrofosmin with those of 201Tl and coronary angiography. In three normal volunteers the images were normal by both 201Tl and tetrofosmin (planar and SPECT). In 23 patients with coronary artery disease, the images were abnormal in 20 patients by SPECT tetrofosmin, in 19 by planar tetrofosmin, in 20 by SPECT thallium, and in 18 by planar thallium (difference not significant). Both planar and SPECT images were divided into five segments per patient. There were 58 perfusion defects by SPECT tetrofosmin, 50 by planar tetrofosmin (difference not significant), 47 by SPECT thallium, and 42 by planar thallium (difference not significant). Perfusion defects were reversible in 47 segments (36%) by SPECT tetrofosmin, 35 (27%) by planar tetrofosmin, 31 (24%) by SPECT thallium (p < 0.05 vs SPECT tetrofosmin), and 31 (24%) by planar thallium (difference not significant). Among the 23 patients with coronary artery disease, 19 underwent coronary angiography. In these patients there were 32 diseased coronary arteries. Perfusion defects were present in 21 territories (66%) by SPECT tetrofosmin, 19 (59%) by planar tetrofosmin, 20 (63%) by SPECT thallium, and 18 (56%) by planar thallium. There was agreement between thallium and tetrofosmin in 108 of 130 segments (kappa statistics = 0.69 +/- 0.06). The images, especially with SPECT, are better with tetrofosmin than with 201Tl. Thus myocardial imaging with tetrofosmin provides results that are at least as good as those of 201Tl. Slightly more abnormal segments and more reversible defects are detected by tetrofosmin than by thallium imaging, especially with SPECT imaging.

Adult↗
PubMedDate not supplied

Pharmacologic stress testing: mechanism of action, hemodynamic responses, and results in detection of coronary artery disease.

Pharmacologic stress testing may be used in the diagnosis of coronary artery disease and risk assessment. The stress agents may be divided into those that produce primary coronary vasodilation (dipyridamole, adenosine, or adenosine triphosphate) and those that produce secondary vasodilation as a result of increase in myocardial oxygen demand (dobutamine and arbutamine). Assessment of myocardial perfusion and function can be made by single-photon imaging, positron emission tomography, two-dimensional echocardiography, magnetic resonance imaging, and contrast angiography. For assessment of myocardial perfusion, either thallium 201-labeled or technetium-labeled perfusion imaging agents may be used. This article will focus on the mechanisms of action, hemodynamic responses, and results of pharmacologic imaging in detecting coronary artery disease. The use of pharmacologic stress testing in risk assessment will be discussed in a separate article.

Adenosine↗
PubMedDate not supplied

Prognostic value of adenosine single-photon emission computed tomographic thallium imaging in medically treated patients with angiographic evidence of coronary artery disease.

BACKGROUND: This study examined the prognostic value of adenosine single-photon emission computed tomographic thallium imaging in medically treated patients with angiographic evidence of coronary artery disease (CAD). METHODS AND RESULTS: Patients who underwent coronary revascularization within 3 months of this study were excluded. There were 177 patients aged 64 +/- 11 years; 74 had one-vessel, 57 had two-vessel, and 46 had three-vessel CAD (> or = 50% diameter stenosis). During a mean follow-up of 22 +/- 13 months, there were 14 events (cardiac death or nonfatal myocardial infarction). Cox survival analysis with important clinical, catheterization, and scintigraphic variables identified the size of perfusion abnormality as the strongest predictor of events (chi 2 = 9). Life-table analysis showed that patients with perfusion defects of 15% or greater of the myocardium had a worse prognosis than had patients with no or smaller defects (Mantel-Cox statistic = 13; p < 0.001). CONCLUSIONS: Thus adenosine single-photo emission computed tomographic thallium imaging provides important prognostic data in medically treated patients with CAD. The extent of thallium abnormality is the most important predictor of events.

Adenosine↗
PubMedDate not supplied

Prognostic significance of silent ischemia.

This study examined the prognostic predictors in 521 patients with angiographic evidence of coronary artery disease (CAD). All patients underwent exercise single-photon emission computed tomographic thallium imaging. The patients were divided into those with symptomatic ischemia defined as reversible thallium defects, S-T segment depression (or both) and angina during exercise (n = 210, group 1), and silent ischemia defined as thallium defects or ST segment depression (or both) but no angina during exercise (n = 311, group 2). During a mean follow-up of 24 +/- 21 months, there were 30 cardiac events (death or nonfatal myocardial infarction). The extent of CAD (2.0 +/- 0.8 diseased vessels in group 1 and 2.1 +/- 0.8 diseased vessels in group 2), the left ventricular ejection fraction, the extent of perfusion abnormality (21% +/- 11% in group 1 and 24% +/- 12% in group 2), and the peak heart rate and double product were similar in the two groups. Survival analysis showed no significant difference in the event-free survival in patients with symptomatic or silent ischemia. The 2-year event-free survival rate was 95% in group 1 and 94% in group 2 (difference not significant). The extent of perfusion abnormality and history of diabetes mellitus were the most important predictors of events. Thus the prognosis of medically treated patients with CAD is comparable in those patients with silent or symptomatic ischemia and is dependent on the extent of myocardium at risk rather than presence or absence of angina pectoris during exercise.

Adult↗
PubMedDate not supplied

Comparison of the treadmill exercise score and single-photon emission computed tomographic thallium imaging in risk assessment.

BACKGROUND: This study compared the prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging with that of treadmill exercise score in medically treated patients with coronary artery disease (CAD). METHODS AND RESULTS: The treadmill exercise score was derived from exercise duration, degree of ST segment depression, and the treadmill anginal index. There were 121 patients with no CAD and 316 patients with angiographically defined CAD (> or = 50% diameter stenosis of one or more vessels). During a mean follow-up of 29 months, there were 35 cardiac deaths or nonfatal myocardial infarctions. Multivariate Cox survival analysis showed the extent of thallium imaging abnormality and CAD to be independent predictors of prognosis. On the other hand, the treadmill exercise score was not a significant predictor even on univariate analysis. The results of thallium uptake were the strongest independent predictors of prognosis and in addition provided incremental prognostic power to coronary angiography (chi 2 = 29 for SPECT, 27 for coronary angiography, and 37 for both). CONCLUSIONS: Thus exercise SPECT thallium imaging is significantly better than the treadmill exercise score in risk assessment. The size of the perfusion abnormality is an important predicator of prognosis.

Adult↗
PubMedDate not supplied

Impact on exercise single-photon emission computed tomographic thallium imaging on patient management and outcome.

BACKGROUND: Stress perfusion imaging is useful in risk stratification of patients with known or suspected coronary artery disease. In the current era of managed health care, there is a need to provide data on patient outcome. METHODS AND RESULTS: This study examined the impact of exercise single-photon emission computed tomographic (SPECT) thallium imaging on patient management (the subsequent need for coronary angiography and revascularization) and outcome (the occurrence of hard cardiac events defined as cardiac death or nonfatal acute myocardial infarction) in 2700 patients who were being evaluated for diagnostic purposes. None of the patients had previous coronary angiography, coronary revascularization, or Q-wave myocardial infarction. The SPECT images were normal in 2027 patients (group 1) and abnormal in 673 patients (group 2). Within 6 months after thallium imaging 53 patients in group 1 (3%) and 242 patients in group 2 (36%) underwent coronary angiography (p = 0.0001). The patients who underwent coronary angiography had higher pretest probability of coronary disease (group 1) or more perfusion defects (group 2) than patients who did not (p = 0.0001 each). Coronary revascularization within 3 months of coronary angiography was performed in 1 of the 53 patients (2%) in group 1 and in 87 of 242 patients (30%) in group 2 (p = 0.0001). Among the remaining patients who had coronary angiography but were medically treated there were no hard cardiac events in group 1 but there were 15 events in group 2 (p = 0.02). CONCLUSIONS: The results of exercise SPECT thallium imaging are important in patient management and outcome. Coronary angiography, coronary revascularization and events are rare in patients with normal exercise SPECT thallium images.

Adult↗
PubMedDate not supplied

Assessment of myocardial viability by dynamic tomographic iodine 123 iodophenylpentadecanoic acid imaging: comparison with rest-redistribution thallium 201 imaging.

BACKGROUND: This study examined the ability of dynamic 123I-labeled iodophenylpentadecanoic acid (IPPA) imaging to detect myocardial viability in patients with left ventricular (LV) dysfunction caused by coronary artery disease. METHODS AND RESULTS: Serial 180-degree single-photon emission computed tomographic (SPECT) images (five sets, 8 minutes each) were obtained starting 4 minutes after injection of 2 to 6 mCi 123I at rest in 21 patients with LV dysfunction (ejection fraction [EF] 34% +/- 11%). The segmental uptake was compared with that of rest-redistribution 201Tl images (20 segments/study). The number of perfusion defects (reversible and fixed) was similar by IPPA and thallium (11 +/- 5 vs 10 +/- 5 segments/patient; difference not significant). There was agreement between IPPA and thallium for presence or absence (kappa = 0.78 +/- 0.03) and nature (reversible, mild fixed, or severe fixed) of perfusion defects (kappa = 0.54 +/- 0.04). However, there were more reversible IPPA defects than reversible thallium defects (7 +/- 4 vs 3 +/- 4 segments/patient; p = 0.001). In 14 patients the EF (by gated pool imaging) improved after coronary revascularization from 33% +/- 11% to 39% +/- 12% (p = 0.002). The number of reversible IPPA defects was greater in the seven patients who had improvement in EF than in the patients without such improvement (10 +/- 4 vs 5 +/- 4 segments/patient; p = 0.075). CONCLUSIONS: 123I-labeled IPPA SPECT imaging is a promising new technique for assessment of viability. Reversible defects predict recovery of LV dysfunction after coronary revascularization.

Adult↗
PubMedDate not supplied

Independent and incremental prognostic value of exercise thallium single-photon emission computed tomographic imaging in women.

BACKGROUND: This study examined the independent and incremental prognostic value of exercise thallium single-photon emission computed tomographic imaging in 212 women who also underwent coronary angiography. METHODS AND RESULTS: The left ventricular ejection fraction was normal (65% +/- 15%). During a mean follow-up of 40 months, 27 women had events (cardiac death or nonfatal myocardial infarction). Univariate Cox survival analysis showed several variables to be different between patients with events and those without events: age, exercise heart rate, the extent of coronary artery disease, reversible thallium defects, number of segments with reversible abnormality, and size of perfusion abnormality. Multivariate survival analysis showed that a large perfusion abnormality and age were the independent predictors of events. Actuarial life-table analysis showed that women with a large thallium abnormality (> or = 15% of the myocardium) had significantly worse event-free survival rates than had women with no or small abnormalities (Mantel-Cox statistic = 16; p = 0.0001). CONCLUSIONS: Thus exercise thallium-201 single-photon emission computed tomographic imaging provides independent and incremental prognostic information to clinical, exercise, and coronary angiographic results in women. The presence of a larger thallium abnormality identifies women at high risk of cardiac events.

Adult↗
PubMedDate not supplied

Prognostic value of tomographic rest-redistribution thallium 201 imaging in medically treated patients with coronary artery disease and left ventricular dysfunction.

BACKGROUND: Previous studies show that rest-redistribution thallium imaging is useful in the assessment of myocardial viability. The impact of such studies on patient outcome is not well defined. This study examined the prognostic value of tomographic rest-redistribution 201T1 imaging in 81 medically treated patients with coronary artery disease and left ventricular dysfunction. METHODS AND RESULTS: Rest-redistribution single-photon emission computed tomographic images were obtained and analyzed quantitatively. The segmental thallium uptake (20 segments per patient) was interpreted as normal, reversible defect, mild to moderate fixed defect, or severe fixed defect. The thallium images were abnormal in 80 patients, with no redistribution (no ischemia) in 43 patients and redistribution (ischemia) in 38 patients. The left ventricular ejection fraction was 27% +/- 8% in patients with no redistribution and 26% +/- 7% in patients with redistribution (difference not significant). In patients with no ischemia, there were 7 +/- 5 severe fixed defects and 5 +/- 4 mild to moderate fixed defects per patient. In patients with ischemia there were 7 +/- 4 reversible defects, 3 +/- 3 mild to moderate fixed defects, and 5 +/- 4 severe fixed defects per patient. The number of any abnormal segments was 11 +/- 5 in patients with no ischemia and 14 +/- 4 in patients with ischemia (p = 0.03). During a mean follow-up of 31 +/- 24 months, there were 11 cardiac deaths in patients with no ischemia (26%) and 22 in patients with ischemia (58%); the survival rate was worse in patients with than without ischemia (p < 0.05). Multivariate Cox survival analysis on important clinical, angiographic, and thallium variables showed that the presence of redistribution was an independent predictor of death (x2 = 5; p = 0.03). CONCLUSIONS: Patients with left ventricular dysfunction and redistribution on rest thallium imaging, a marker of hibernating myocardium, have a higher mortality rate with medical therapy than do patients with a comparable degree of left ventricular dysfunction but with fixed defects only. Thus observations similar to those made with positron emission tomography can be made in a much more straightforward, simple, and probably cost-effective manner with single-photon emission computed tomography.

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PubMedDate not supplied

Comparison of left ventricular performance in healthy young women and men during exercise.

BACKGROUND: Previous studies show sex-related differences in left ventricular (LV) response to exercise. It is not clear, however, whether these differences are also seen in younger healthy subjects. METHODS AND RESULTS: This study examined the changes in LV performance during dynamic upright exercise in 11 healthy men and 19 healthy young women according to the Bruce protocol and an individualized ramp protocol. There were no significant differences between the two protocols for either men or women in heart rate, blood pressure, LV ejection fraction (EF) (measured by ambulatory nuclear detector), and measured oxygen consumption. The peak oxygen consumption was higher in men than in women (44 +/- 13 vs 36 +/- 9 ml/kg/min; p < 0.05), but the peak heart rate, systolic blood pressure, and EF were similar. The change in EF (from rest to exercise) was 19% +/- 8% in men and 19% +/- 11% in women with the Bruce protocol (difference not significant) and 26% +/- 9% in men and 19% +/- 6% in women with the ramp protocol (difference not significant). At peak exercise, both men and women showed an increase in end-diastolic volume (29% +/- 14% vs 23% +/- 11%; difference not significant) and a decrease in end-systolic volume (41% +/- 15% vs 43% +/- 21%) (difference not significant). The increase in cardiac output during exercise was due to an increase in heart rate and stroke volume in both men and women. At submaximal exercise, however, the decrease in end-systolic volume was less in women than in men (p < 0.05). CONCLUSIONS: There are no sex-related differences in compensatory mechanism during dynamic exercise in healthy subjects. The changes in contractility and LV volume are not affected by the exercise protocol.

Adult↗
PubMedDate not supplied

Prognostic value of stress myocardial perfusion single photon emission computed tomography imaging in patients with left ventricular bundle branch block.

BACKGROUND: Left bundle branch block (LBBB) may occur with or without structural heart disease. In patients with coronary artery disease the presence of LBBB is associated with an increased risk of cardiovascular events. METHODS AND RESULTS: This study examined the outcome of 293 medically treated patients with LBBB and symptoms who were undergoing stress thallium-201 single photon emission computed tomography imaging. One hundred seventy-three men and 120 women with an age range of 67 +/- 9 years and a pretest probability of coronary artery disease of 77% +/- 28% were studied. During a mean follow-up of 33 months 58 hard cardiac events (death or nonfatal myocardial infarction) and 112 total events (hard events, coronary angioplasty, coronary bypass surgery, or cardiac transplantation) occurred. Univariate and multivariate Cox survival analysis with clinical, stress, hemodynamic, and single photon emission computed tomography variables identified the perfusion defect size (chi square = 27, p = 0.0001) and increased lung thallium uptake as the most important independent predictors of hard or total cardiac events. The hard event-free survival rate was 91% in patients with no or small defects (<15% of left ventricular myocardium) and 72% in patients with large defects (p = 0.0001, RR = 3.2, 95% CI 1.7 to 5.9). The total event-free survival rate was 81% in patients with small defects and 48% in patients with large defects (p = 0.0001, RR = 2.7, 95% CI 1.9 to 4.0). The total event rate was 54% in patients with large perfusion defects and increased lung uptake and 17% in patients with no or small abnormality and normal lung thallium uptake (p = 0.0001). CONCLUSION: Single photon emission computed tomography perfusion imaging is useful in predicting outcome in patients with LBBB and intermediate pretest probability of coronary artery disease. The size of perfusion abnormality and lung thallium uptake stratified patients into high and low risk groups with a threefold difference in hard and total cardiac events.

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