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Biomedical subjects

Y L Doi

Publications and source records attributed to Y L Doi.

At least 19 recordsLinked to original sources
PubMed1995

Determinants of exercise capacity in the hypertensive elderly--a study based on the assessment of cardiac reserve by dipyridamole radionuclide angiography.

To evaluate the determinants of exercise capacity in the hypertensive elderly with an assessment of cardiac reserve by dipyridamole radionuclide angiography, 31 elderly subjects (aged 62 to 78 years, 15 hypertensive and 16 normotensive) underwent symptom-limited maximum treadmill exercise with measurement of maximal oxygen consumption along with radionuclide angiography in list mode at rest and after dipyridamole infusion. In the normotensive elderly, maximal oxygen consumption correlated with relative filling volume during the rapid filling period at rest (r = 0.58; p < 0.05), and correlated inversely with the percent change in the peak ejection rate with dipyridamole (r = -0.63; p < 0.01). In contrast, maximal oxygen consumption correlated with atrial contribution at rest (r = 0.69; p < 0.005), and correlated inversely with the percent change in atrial contribution with dipyridamole (r = -0.87; p < 0.0001) in the hypertensive elderly. These results indicate that the mechanisms for maintaining exercise capacity are different in elderly subjects with or without hypertension.

Aged↗
PubMed1994

Diagnostic value of transient dilatation of the left ventricle in negative dipyridamole-thallium imaging.

To evaluate the diagnostic value of a transient dilatation of the left ventricle during dipyridamole-thallium imaging (DTI) for detecting significant coronary artery disease (CAD) in patients with negative DTI results, 81 consecutive patients were studied. Twenty one patients (26%) had CAD and 60 patients had normal coronary anatomy (NCA). The initial/delayed ratio of the left ventricular dimension, which was measured as the distance between the 2 peaks of a count profile curve on a 45 degrees left anterior oblique planar image, was defined as the dilatation ratio (DR) of the left ventricle. Patients with CAD had a higher incidence of chest pain after dipyridamole infusion (35 vs 13%; p < 0.05), and ST depression during exercise testing (50 vs 25%; p < 0.05) than those with NCA. DR was significantly greater in CAD patients than in NCA patients (1.08 +/- 0.10 vs 0.97 +/- 0.03; p < 0.0001). DR was considered abnormal (> 1.03) when it was greater than the mean +2 standard deviations of the DR in NCA patients. Seventy-six percent of CAD patients had an abnormal DR. A stepwise discriminant analysis revealed that an abnormal DR alone had the same ability to predict CAD (sensitivity 76%, specificity 98%, chi-square 80.9, p < 0.0001) as the best combination of abnormal DR, chest pain during exercise testing, age and gender (sensitivity 76%, specificity 98%, chi-square 98.5, p < 0.0001). When abnormal DR was excluded from this analysis, the best combination of the variables showed a reduced ability to predict CAD (sensitivity 81%, specificity 77%, Wilks' Lambda 0.71, chi-square 26.7, p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Value of dipyridamole thallium-201 imaging in noninvasive differentiation of idiopathic dilated cardiomyopathy from coronary artery disease with left ventricular dysfunction.

The purpose of this study was to noninvasively differentiate in patients with reduced global left ventricular function between those with idiopathic dilated cardiomyopathy (IDC) and coronary artery disease (CAD). Clinical features and findings of dipyridamole thallium-201 imaging in 55 consecutive patients with IDC were compared with those in 77 with CAD. Left ventricular ejection fraction was similar between the 2 groups (34 +/- 16% vs 39 +/- 7%). Patients with IDC had lower incidences of ischemic chest pain (11 vs 79%; p less than 0.0001), electrocardiographic evidence of myocardial infarction (24 vs 82%; p less than 0.0001), and reversible defects (4 vs 57%; p less than 0.0001) than did those with CAD. The lowest percent thallium uptake in the initial imaging was less with CAD than IDC (30 +/- 15% vs 59 +/- 10%; p less than 0.001). Patterns of perfusion defects were classified as: no defects, multiple small defects and large defects. Of patients with IDC, 15 had no defects, 19 had multiple small defects, and 21 had large defects, whereas all those with CAD had large defects (p less than 0.0001). Stepwise discriminant analysis, using chest pain and electrocardiography, revealed sensitivity of 89%, specificity of 87%, accuracy of 88%, and positive predictive value of 83% in the identification of patients with IDC.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Mechanisms of exercise limitation in hypertrophic cardiomyopathy.

To assess the relation of exercise capacity to indexes of systolic and diastolic function in hypertrophic cardiomyopathy, 81 patients underwent two-dimensional echocardiography, technetium-99m equilibrium radionuclide angiography acquired in list mode and maximal, symptom-limited, treadmill exercise testing with measurement of maximal oxygen consumption (VO2 max). VO2 max for the group was 13.9 to 49.3 (mean 25.4) ml/min per kg. Thirty-six patients (44%) achieved less than or equal to 70% of age-predicted VO2 max. Patients with such a degree of limitation were more likely to be in New York Heart Association functional class II or III (23 of 36 vs. 14 of 45; p = 0.005); there was no such relation between VO2 and the incidence and magnitude of rest left ventricular outflow tract pressure gradient greater than 30 mm Hg (11 of 36 vs. 11 of 45; p = NS and 58 +/- 24 vs. 65 +/- 19 mm Hg; p = NS). In the 22 patients with a left ventricular outflow tract gradient, the ratios of peak ejection to peak filling rate and of atrial contribution to left atrial dimension were related to percent of the age-predicted VO2 max (r = 0.49, p = 0.02 and r = 0.54, p less than 0.02). These ratios reflect impaired left ventricular systolic performance and atrial systolic failure, respectively. Stepwise discriminant analysis revealed these two ratios to be the two strongest predictors (p = 0.0001) of patients with a left ventricular outflow tract gradient whose VO2 max was less than or equal to 70% of the age-predicted value (sensitivity 90%, specificity 100%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Noninvasive identification of significant narrowing of the left main coronary artery by dipyridamole thallium scintigraphy.

To evaluate the usefulness of dipyridamole thallium scintigraphy with low-level exercise for the identification of left main (LM) coronary artery disease (CAD), 466 consecutive patients with CAD were studied. Thirty-eight patients (8%) had LM stenosis (diameter narrowing greater than or equal to 50%). The LM scintigraphic pattern was present in 9 of 38 patients with LMCAD and 38 of 428 CAD patients without LMCAD (24 vs 9%; p less than 0.005). This pattern was present in 6 of 9 patients with LMCAD without right CAD and in only 3 of 29 patients with LM and right CAD (67 vs 10%; p = 0.0005). Patients with LMCAD had a higher incidence of premature cessation of low-level exercise (53 vs 21%; p less than 0.0001), chest pain (68 vs 48%; p less than 0.02), blood pressure decrease of greater than or equal to 20 mm Hg (44 vs 16%; p less than 0.002) and greater ST depression (0.17 +/- 0.13 vs 0.06 +/- 0.10 mV; p less than 0.001) during dipyridamole loading than patients without LMCAD. Stepwise discriminant analysis revealed that the LM scintigraphic pattern and markers of ischemia during dipyridamole loading best identified (p less than 0.0001) patients with LMCAD without right CAD (sensitivity 67%, specificity 91%), but this predictability is no better than the LM scintigraphic pattern alone. The combination of clinical markers of ischemia during dipyridamole loading and scintigraphic findings of diffuse slow washout, extensive fixed defects and the LM pattern best identified (p less than 0.0001) patients with LM and right CAD (sensitivity 72%, specificity 80%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Prognostic value of thallium-201 perfusion defects in idiopathic dilated cardiomyopathy.

To assess the prognostic significance of thallium-201 perfusion defects in patients with idiopathic dilated cardiomyopathy (IDC), 43 patients underwent thallium scintigraphy in addition to clinical, echocardiographic, angiographic and hemodynamic evaluation. Eleven patients had no significant thallium perfusion abnormality, 19 had multiple small defects and 13 had a large defect. During 3.2 +/- 2.2 years, 14 patients had disease-related mortality. The patients who died had a higher incidence of ventricular tachycardia (71 vs 31%; p less than 0.02), increased cardiothoracic ratio (60 +/- 6 vs 54 +/- 6; p = 0.005), decreased fractional shortening (11 +/- 6 vs 15 +/- 5; p less than 0.05), increased pulmonary wedge pressure (15 +/- 7 vs 10 +/- 6 mm Hg; p = 0.05), increased left ventricular end-diastolic pressure (21 +/- 8 vs 14 +/- 6 mm Hg; p = 0.02) and abnormal thallium perfusion defects (13 of 14 vs 16 of 26; p less than 0.05) compared with survivors. Age, gender, left ventricular end-systolic and end-diastolic dimensions, cardiac index and ejection fraction were not statistically different in the survivors versus the patients who died. Kaplan-Meier survival estimates at 1, 3 and 5 years were 100% in patients without significant perfusion abnormality; 89, 77 and 64%, respectively, in patients with multiple small defects; and 84, 76 and 30%, respectively, in patients with a large defect (p less than 0.025 by log rank test).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1990

Aortic regurgitation secondary to Behçet's disease. A case report and review of the literature.

Cardiac complications, especially aortic regurgitation, are very rare in Behçet's disease. This report describes a patient with a complicated abnormality of the aortic valve apparatus and severe aortic regurgitation secondary to Behçet's disease. In the literature, flail prolapsed valve, perforated valves and ruptured pseudoaneurysms of the sinus of Valsalva have been reported. Echocardiography may be most useful to detect these anatomically complex abnormalities and therefore to elucidate the cause of aortic regurgitation in Behçet's disease.

Aortic Valve Insufficiency↗
PubMed1988

Takayasu's arteritis and mitral stenosis.

A 44-year-old housewife was found to have coarctation of the abdominal aorta secondary to Takayasu's arteritis. Since she also had mitral stenosis, possible etiological relation between Takayasu's arteritis and mitral stenosis is suspected.

Adult↗
PubMed1987

Myocardial bridging of the left anterior descending coronary artery without relation to the site of hypertrophy in hypertrophic cardiomyopathy.

Myocardial bridging of the left anterior descending coronary artery producing complete systolic occlusion was demonstrated in a patient with hypertrophic cardiomyopathy, who had localized myocardial hypertrophy in the lateral left ventricular wall outside the territory of that artery. Although a cause and effect relationship between systolic compression of the coronary artery and myocardial hypertrophy has previously been postulated in hypertrophic cardiomyopathy, the lack of relation between the site of the myocardial bridging and the region of the left ventricular hypertrophy in our patient suggests that the myocardial bridging of the left anterior descending coronary artery may not be related to the pathogenesis of asymmetric septal hypertrophy.

Adult↗
PubMed1987

Ring-calcification of coronary artery aneurysms in an adolescent.

A 17-year-old asymptomatic boy with a history of Kawasaki disease in infancy was found to have an abnormal ring-calcification as seen in the chest roentgenogram and the electrocardiographic evidence of anteroseptal myocardial infarction. Coronary angiogram revealed aneurysms associated with ring-calcifications in the right coronary artery and subtotal obstruction of the left anterior descending coronary artery. A plain chest roentgenogram may, at times, be useful for identifying coronary aneurysms in patients with a possible history of Kawasaki disease.

Adolescent↗
PubMed1985

Diastolic time during recovery from upright exercise in persons without heart disease.

To assess the relation between heart rate and diastolic time (cardiac cycle minus electromechanical systole) during the recovery period from upright exercise, 12 normal volunteers were studied immediately after and 2 and 5 minutes after exercise in the upright position. Although heart rate was significantly lower at 5 minutes compared with 2 minutes after exercise (106 vs 116 beats/min), there was significant shortening of diastolic time (from 251 to 230 ms) and total diastole per minute (from 28,634 to 24,220 ms/min). The explanation of this phenomenon appears to be disproportionate lengthening of diastolic time at 2 minutes after exercise, which must represent physiologic response due to increased left ventricular filling as well as continuing adrenergic effects, which would be diminished at 5 minutes. This lengthening of diastolic time also would maintain decreased subendocardial blood flow caused by increased end-diastolic volume.

Adult↗
PubMed1984

Systolic time intervals reconsidered. Reevaluation of the preejection period: absence of relation to heart rate.

Within limits, systolic time intervals are reliable reflectors of cardiac status and responses to physiologic and pharmacologic challenges, with various functional correlates. That heart rate (HR) is an important determinant of the duration of systole is well accepted, owing to its effect on left ventricular ejection time (LVET). An independent rate effect on preejection period (PEP) is disputed. Some studies in pooled normal subjects at rest showed some degree of HR-PEP covariance, leading to widespread rate correction in practical use. However, although right atrial pacing showed the expected HR-LVET relation, it consistently failed to show an HR-PEP relation. Systolic time intervals were examined from echocardiograms of a deliberately heterogeneous group comprising 50 consecutively appearing persons with sinus rhythm. There was no HR-PEP covariance (r = 0.23; p = not significant). However, our subjects were otherwise comparable to those of other investigators, in that all other relations in these subjects were as expected from studies in both pooled and paced subjects: HR with LVET (r = -0.74; p less than 0.001), PEP/LVET with ejection fraction (r = -0.85; p less than 0.001), and PEP/LVET with velocity of circumferential fiber shortening (r = -0.65, p less than 0.001). Thus, HR correction of PEP is inappropriate. All other relations are substantiated in routinely encountered, unselected subjects.

Adolescent↗
PubMed1984

Echocardiographic study of left ventricular wall motion in mitral valve prolapse.

A distinct late systolic "dip" in ventricular wall motion is described in patients with mitral valve prolapse. Sixty patients were referred because of clinically suspected mitral valve prolapse. Thirty of these patients had M-mode echocardiograms showing mitral valve prolapse. An abnormal late systolic "dip" in posterior wall motion was present at chordal level in 9 of 30 patients with prolapse but none of 27 patients without prolapse. All of these nine patients had late systolic prolapse and greater mean velocity of circumferential fiber shortening than 21 patients with prolapse but without the "dip" at chordal level (1.6 +/- 0.3 vs 1.3 +/- 0.2, p less than 0.02). Two of these nine patients had several episodes of transient cerebral ischemic attacks. Direct mural compression by the posterior chordae is offered as a possible mechanism for this echographic wall motion finding.

Adolescent↗