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Biomedical subjects

C A Boucher

Publications and source records attributed to C A Boucher.

At least 145 records · Page 8Linked to original sources
PubMed1990

Serial evaluation of right ventricular dysfunction associated with acute inferior myocardial infarction.

Right ventricular (RV) function was evaluated serially by multigated blood pool imaging in 18 patients with RV dysfunction associated with acute inferior myocardial infarction. Radionuclide ventriculograms were performed on all patients within 18 hours of chest pain and again at 10 days. In addition, 15 of 18 patients had rest and exercise radionuclide ventriculograms at 3 months. The mean resting right ventricular ejection fractions (RVEF) at admission, 10 days, and 3 months in these patients was 31.8 +/- 12.6% (SD), 46.9 +/- 11.2% (p less than 0.05), and 44.5 +/- 10.2% (p less than 0.05), while the left ventricular ejection fractions were 55.9 +/- 10.6%, 57.9 +/- 13.3%, and 53.1 +/- 11.2% (p = ns). The 3-month exercise radionuclide ventriculogram demonstrated an increase in RVEF greater than 5% in 6 of 15 patients. In eight catheterized patients, neither the location nor the severity of coronary artery narrowing nor the presence of collaterals correlated with the RV exercise response. Improvement in RV function over a 10-day interval following acute inferior myocardial infarction suggests the presence of significant reversible right ventricular dysfunction during the acute phase.

Cardiac Catheterization↗
PubMed1990

Exercise electrophysiology testing: the effect of exercise on the induction of ventricular arrhythmias by programmed ventricular stimulation.

In order to assess the effect of acute, reversible myocardial ischemia on the outcome of programmed ventricular stimulation (PVS), ventricular stimulation was performed at rest, during exercise, and during recovery in 10 patients with coronary artery disease. Of these ten patients, four were tested while off antiarrhythmic drugs and six were tested on antiarrhythmic drug therapy. Nine of the ten patients developed acute myocardial ischemia during exercise PVS. However, in only two of these ten patients ventricular arrhythmia could be induced by PVS, one during exercise and one during recovery.

Aged↗
PubMed1990

Epstein-Barr virus in a CD8-positive T-cell lymphoma.

In contrast to its role in B-lymphomagenesis, Epstein-Barr Virus (EBV) only incidentally has been associated with T-cell lymphomas. In the present report we describe a fourth patient with EBV-related T-cell lymphoma. The patient presented with an angio-immunoblastic lymphadenopathy (AILD)-like T-cell lymphoma. Serology was compatible with chronic Epstein-Barr (EBV) infection. After a 1-year period of waxing and waning lymphadenopathy, this lymphoma evolved to an aggressive CD8+ Immunoblastic T-cell lymphoma. A relationship with the chronic EBV infection was indicated by the finding of EBV genome in the tumor tissue by Southern blot analysis. Moreover, EBV nuclear antigen (EBNA) was detected in situ within individually defined CD8+ tumor cells by two-color immunofluorescence. Two alternative possibilities, namely that EBV primarily played a role in lymphomagenesis of the AILD-like T-cell lymphoma or that the virus was an additional oncogenic event in the final process of tumor progression to the immunoblastic lymphoma, are discussed.

Adult↗
PubMed1989

Prognostic utility of predischarge dipyridamole-thallium imaging compared to predischarge submaximal exercise electrocardiography and maximal exercise thallium imaging after uncomplicated acute myocardial infarction.

The prognostic value of predischarge dipyridamole-thallium scanning after uncomplicated myocardial infarction was determined by comparison with submaximal exercise electrocardiography and 6-week maximal exercise thallium imaging and by correlation with clinical events. Two endpoints were defined: cardiac events and severe ischemic potential. Of the 40 patients studied, 8 had cardiac events within 6 months (1 died, 3 had myocardial infarction and 4 had unstable angina requiring hospitalization). The finding of any redistribution on dipyridamole-thallium scanning was common (77%) in these patients and had poor specificity (29%). Redistribution outside of the infarct zone, however, had equivalent sensitivity (63%) and better specificity (75%) for events (p less than 0.05). Both predischarge dipyridamole-thallium and submaximal exercise electrocardiography identified 5 of the 8 events (p = 0.04 and 0.07, respectively). The negative predictive accuracy for events for both dipyridamole-thallium and submaximal exercise electrocardiography was 88%. In addition to the 8 patients with events, 16 other patients had severe ischemic potential (6 had coronary bypass surgery, 1 had inoperable 3-vessel disease and 9 had markedly abnormal 6-week maximal exercise tests). Predischarge dipyridamole-thallium and submaximal exercise testing also identified 8 and 7 of these 16 patients with severe ischemic potential, respectively. Six of the 8 cardiac events occurred before 6-week follow-up. A maximal exercise thallium test at 6 weeks identified 1 of the 2 additional events within 6 months correctly. Thallium redistribution after dipyridamole in coronary territories outside the infarct zone is a sensitive and specific predictor of subsequent cardiac events and identifies patients with severe ischemic potential.(ABSTRACT TRUNCATED AT 250 WORDS)

Dipyridamole↗
PubMed1989

Inotropic effect of nicardipine in patients with heart failure: assessment by left ventricular end-systolic pressure-volume analysis.

Nicardipine, a new dihydropyridine calcium channel blocker, has been investigated for the treatment of coronary artery disease and heart failure. To assess the inotropic effect of nicardipine in humans independent of its vasodilator effect, equihypotensive doses of intravenous nitroprusside (mean infusion rate 65 +/- 13 micrograms/min) and nicardipine (mean dose 5.2 +/- 0.4 mg) were administered to 15 patients with heart failure (New York Heart Association functional classes II to IV, radionuclide left ventricular ejection fraction 0.15 +/- 0.02). Left ventricular micromanometer pressure and simultaneous radionuclide left ventricular volume were obtained at baseline, during nitroprusside infusion, during a second baseline period and during nicardipine infusion. Heart rate did not change significantly with either nitroprusside or nicardipine. Mean systemic arterial pressure decreased by an average of 21 mm Hg with both drugs. A greater decrease in left ventricular end-diastolic pressure occurred with nitroprusside (27 +/- 2 to 14 +/- 2 mm Hg, p less than 0.01) than with nicardipine (27 +/- 2 to 23 +/- 3 mm Hg, p less than 0.05), and pulmonary capillary wedge pressure decreased significantly only with nitroprusside. Cardiac index increased from 1.8 +/- 0.1 to 2.1 +/- 0.1 liters/min per m2 (p less than 0.05) with nitroprusside and to a greater extent from 1.7 +/- 0.1 to 2.4 +/- 0.1 liters/min per m2 (p less than 0.01) with nicardipine. Left ventricular ejection fraction increased with nicardipine (0.15 +/- 0.01 to 0.19 +/- 0.01, p less than 0.01), but not with nitroprusside. Peak positive first derivative of left ventricular pressure (dP/dt) decreased by 9% with both agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1989

Nifedipine, but not propranolol, improves left ventricular systolic and diastolic function in patients with hypertension.

The effects of nifedipine and propranolol on cardiac function both at rest and at peak exercise were compared in 22 hypertensive patients whose diastolic blood pressures remained in excess of 95 mm Hg despite diuretic therapy. In this double-blind, placebo-controlled study, left ventricular systolic and diastolic function at rest and at peak exercise during bicycle ergometry was assessed by first-pass radionuclide angiography using the Baird Scinticor before and after treatment with either nifedipine or propranolol. Both agents effectively reduced blood pressure in the supine and upright positions and at peak exercise. Nifedipine was associated with a significant increase in cardiac output and stroke volume at rest and at peak exercise, while propranolol decreased cardiac output at rest and at peak exercise. Systemic vascular resistance decreased with nifedipine treatment at rest and at peak exercise, but increased significantly with propranolol. Nifedipine increased ejection fraction in patients at rest and also increased maximal oxygen consumption at peak exercise, while propranolol decreased maximal oxygen consumption at peak exercise. At rest and at peak exercise, nifedipine increased peak filling rate, but time to peak filling rate was not affected by either drug. The fraction of total diastolic filling at the midpoint of diastole was significantly increased by nifedipine therapy at rest but was not affected by propranolol therapy. Nifedipine significantly decreased atrial filling volume while propranolol had no effect. Propranolol therapy did not result in any improvement in left ventricular function. In contrast, nifedipine improved left ventricular systolic and diastolic function at rest and peak exercise. Future selection of an antihypertensive agent should include consideration of the impact of therapy on left ventricular function.

Adult↗
PubMed1989

Combining clinical and thallium data optimizes preoperative assessment of cardiac risk before major vascular surgery.

STUDY OBJECTIVE: To determine whether clinical markers and preoperative dipyridamole-thallium imaging are both useful in predicting ischemic events after vascular surgery. DESIGN: Retrospective, observational study. SETTING: University medical center. PATIENTS: Two hundred fifty-four consecutive patients referred to a nuclear cardiology laboratory before surgery. Forty-four patients had surgery cancelled or postponed after clinical evaluation and dipyridamole-thallium imaging. Surgery was not confirmed for ten. Two hundred patients receiving prompt vascular surgery were the study group. MEASUREMENTS AND MAIN RESULTS: Thirty patients (15%) had early postoperative cardiac ischemic events, with cardiac death in 6 (3%) and nonfatal myocardial infarction in 9 (4.5%). Logistic regression identified five clinical predictors (Q waves, history of ventricular ectopic activity, diabetes, advanced age, angina) and two dipyridamole-thallium predictors of postoperative events. Of patients with none of the clinical variables (n = 64), only 2 (3.1%; 95% CI, 0% to 8%) had ischemic events with no cardiac deaths. Ten of twenty (50%; 95% CI, 29% to 71%) patients with three or more clinical markers had events. Eighteen of one hundred sixteen (15.5%; 95% CI, 7% to 21%) patients with either 1 or 2 clinical predictors had events. Within this group, 2 of 62 (3.2%; 95% CI, 0% to 8%) patients without thallium redistribution had events compared with 16 events in 54 patients (29.6%; 95% CI, 16% to 44%) with thallium redistribution. The multivariate model using both clinical and thallium variables showed significantly higher specificity at equivalent sensitivity levels than models using either clinical or thallium variables alone. CONCLUSIONS: Preoperative dipyridamole-thallium imaging appears most useful to stratify vascular patients determined to be at intermediate risk by clinical evaluation. For patients with one or two clinical predictors, thallium redistribution correlates with substantial change in probability of events. For nearly half the patients, however, thallium imaging may have been unnecessary because of very high or low cardiac risk predicted by clinical information alone.

Age Factors↗
PubMed1989

Left ventricular performance during psychological stress.

Left ventricular ejection fraction, systolic blood pressure and plasma norepinephrine were measured in six normotensive and six mildly hypertensive subjects during rest and psychological stress. Compared with rest, 8 of the 12 subjects developed significant (P less than 0.05) changes in ejection fraction (increase in 6, decrease in 2); 10 of 12 subjects developed significant elevations of plasma norepinephrine; and all developed significant increases in systolic blood pressure. When the stress effects were examined for the total group, as opposed to within subjects, there were significant increases in plasma norepinephrine (P less than 0.001) and systolic blood pressure (P less than 0.001) but, interestingly, mean ejection fraction and stroke volume remained unchanged, implying stress led to increased left ventricular contractility.

Adult↗
PubMed1989

Acute hemodynamic changes during intravenous dipyridamole thallium imaging early after infarction.

In order to determine the safety and hemodynamic effects of intravenous dipyridamole infusion for thallium-201 scinitigraphy in patients with acute ischemic syndromes, 10 patients with recent uncomplicated myocardial infarction (7 +/- 2 days pre-test) had central pressures and cardiac output values measured serially in a coronary care unit during and after the administration of dipyridamole (0.56 mg/kg over 4 minutes) and following aminophylline reversal (50 to 150 mg intravenously) of dipyridamole effect. Cardiac medications were not discontinued. Double product did not change significantly (8522 +/- 1811 versus 9044 +/- 1701; p = NS). Serious ischemic events did not occur, although 20% of patients had noncardiac side effects and 30% developed greater than or equal to 1 mm ST segment depression with associated angina in one-third of these cases. The peripheral blood pressure and heart rate response did not predict the occurrence of myocardial ischemia. Dipyridamole significantly reduced systemic vascular resistance (1218 +/- 302 to 739 +/- 166 dyne/sec-1/cm-5; p less than 0.05) and increased cardiac index (3.1 +/- 0.7 to 4.7 +/- 1.0 L/min/m2; p less than 0.05) within approximately 10 minutes, in association with a significant increase in pulmonary capillary wedge pressure (13 +/- 5 to 17 +/- 6 mm Hg; p less than 0.05). Three patients developed silent new "V" waves in their pulmonary capillary wedge pressure tracing, associated with anterior thallium redistribution. All three patients with newly elevated wedge pressures (greater than 15 mm Hg) had both thallium-201 redistribution and multivessel coronary disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminophylline↗
PubMed1989

Technetium-99m isonitrile myocardial uptake at rest. I. Relation to severity of coronary artery stenosis.

To determine the potential of planar technetium-99m methoxybutyl isonitrile myocardial imaging as a method of detecting totally occluded or severely stenosed coronary arteries, the regional distribution of technetium-99m isonitrile at rest was compared with the coronary anatomy in 38 patients with prior myocardial infarction who underwent coronary arteriography. Left ventricular technetium-99m isonitrile tracer uptake at rest was assessed in the three major coronary vascular territories. When qualitative rest technetium-99m isonitrile uptake was markedly reduced or absent (grade 0), there was a 91% probability of finding a totally occluded or severely stenosed coronary artery. When qualitative tracer uptake was reduced (grade 1) or normal (grade 2), it excluded all territories supplied by a totally occluded vessel with poor collateral flow. Quantitative technetium-99m isonitrile uptake (mean +/- 1 standard deviation) in territories supplied by an occluded coronary artery with poor collateral flow (42 +/- 21%) was lower than in territories supplied by a vessel with less than 50% stenosis (87 +/- 10%) and 50 to 99% stenosis (74 +/- 19%) (p less than 0.001). Furthermore, technetium-99m isonitrile uptake in areas supplied by an occluded coronary artery with good collateral flow (61 +/- 23%) was lower than in areas supplied by a vessel with less than 50% stenosis (87 +/- 10%) (p less than 0.001). Because rest technetium-99m isonitrile imaging detects coronary occlusion with poor collateral flow, this method may be useful in assessing patients with acute myocardial infarction.

Adult↗
PubMed1989

Technetium-99m isonitrile myocardial uptake at rest. II. Relation to clinical markers of potential viability.

To determine the utility of rest-injected technetium-99m methoxybutyl isonitrile (Tc-99m isonitrile) uptake as a marker of myocardial viability, the regional uptake of this agent was compared with regional wall motion by equilibrium gated blood pool scan in 26 patients with previous myocardial infarction and with postrevascularization uptake in 8 patients after coronary bypass surgery. Rest left ventricular Tc-99m isonitrile uptake was assessed qualitatively in three coronary vascular territories as grade 0 (markedly reduced) to grade 2 (normal), and quantitatively by circumferential profile analysis. Wall motion was scored qualitatively in corresponding vascular territories as normal, hypokinetic or akinetic/dyskinetic. There was an overall relation between qualitative Tc-99m isonitrile uptake and wall motion. Abnormal wall motion occurred in 74% of vascular territories with perfusion grade 0, in 61% of those with grade 1 and in 30% of those with grade 2; however, 26% of territories with grade 0 uptake had normal wall motion. In the territories visually assigned perfusion grade 0, quantitative isonitrile uptake (mean value +/- SD) was higher when corresponding wall motion was normal or hypokinetic (62 +/- 15%) than when akinesia was detected by gated blood pool scan (39 +/- 16%, p less than 0.02). Qualitative Tc-99m isonitrile uptake improved after coronary bypass surgery in 12 of 13 territories with reduced uptake preoperatively; this included all 5 territories with a preoperative Tc-99m isonitrile score of 0. Quantitative uptake in these regions increased from 55 +/- 18% to 73 +/- 21% (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Artery Bypass↗
PubMed1989

Linearity of the left ventricular end-systolic pressure-volume relation in patients with severe heart failure.

The left ventricular end-systolic pressure-volume relation is a relatively load-independent measure of left ventricular contractile function. Linearity of the relation derived from full left ventricular pressure-volume loops has not previously been demonstrated for patients with severe heart failure. Therefore, nine patients with markedly depressed left ventricular systolic function (ejection fraction 0.14 +/- 0.08) were studied with micromanometer left ventricular pressure measurement and simultaneous radionuclide ventriculography. Afterload was reduced with graded infusions of nitroprusside, allowing construction of pressure-volume loops under four afterload conditions in four patients and three afterload conditions in the other five patients. The end-systolic pressure-volume relation derived from the pressure-volume loops was found to be linear for the range of pressures and volumes examined, with correlation coefficients in individual patients ranging from 0.936 to 0.999 (mean 0.981). The mean slope of the relation (or end-systolic elastance) was 0.71 mm Hg/ml (range 0.42 to 1.52), and the extrapolated volume intercept at zero pressure was positive in all patients. An exponential relation between end-systolic elastance and ejection fraction was demonstrated for this group of patients. Approximations of end-systolic elastance obtained from measurements other than the full pressure-volume loops correlated variably with "true" elastance obtained from the pressure-volume loops. The relation between stroke work and end-diastolic volume was nonlinear in most patients. Thus, the end-systolic pressure-volume relation is linear in the "physiologic" range in patients with severe heart failure. This finding should permit construction of the relation from two loading conditions in clinical studies, facilitating its use as an index of contractile function in patients with heart failure.

Aged↗
PubMed1989

Differentiation of restrictive cardiomyopathy from pericardial constriction: assessment of diastolic function by radionuclide angiography.

Diastolic filling variables were studied in 12 patients with the hemodynamic features of constriction, of whom 5 had restrictive cardiomyopathy, 5 had pericardial constriction and 2 had combined pericardial constriction and restrictive cardiomyopathy. The values were compared with those in 10 normal subjects of comparable age. The filling fractions between 10% and 70% of the diastolic time interval were greater in patients with pericardial constriction than in those with restrictive cardiomyopathy (p less than 0.01 between 20% and 50%, p less than 0.05 at 10%, 60% and 70%), with no overlap. The filling fractions in patients with pericardial constriction were also greater than those in normal subjects between 10% and 60% of the diastolic time interval. The filling fraction was lower in patients with restrictive cardiomyopathy than in normal subjects at 40% of the diastolic time interval (p less than 0.05). The time to peak filling rate in patients with pericardial constriction was shorter (110 +/- 14 ms) than in those with restrictive cardiomyopathy (195 +/- 45 ms, p less than 0.01) or in normal subjects (173 +/- 32 ms, p less than 0.01). The percent of atrial contribution to left ventricular filling was higher in those with restrictive cardiomyopathy (45 +/- 17%) than in those with pericardial constriction (21 +/- 6%, p less than 0.05) or in normal subjects (24 +/- 9%, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Antibody response to a synthetic peptide covering a LAV-1/HTLV-IIIB neutralization epitope and disease progression.

Sequential sera of homosexual men participating in a prospective study on the incidence of HIV-1 infection and risk factors for AIDS were tested for the presence of antibodies to a synthetic 17-mer (Neu21; KSIRIQRGPGRAFVTIG) representing a neutralization epitope as present on the LAV-1/HTLV-IIIB strain of HIV-1. Of 191 at entry, 143 (75%) HIV-1-seropositive men remained anti-Neu21-negative during the follow-up period of 36 months. Thirty-seven (19%) HIV-1-seropositive men were persistently anti-Neu21-positive. Eleven (6%) HIV-1 seropositive men seroconverted for anti-Neu21 during follow-up. Of 75 men developing antibodies to HIV-1, 17 (23%) developed antibodies to Neu21. The incidence of anti-Neu21 seroconversion (calculated as attack rate) after 36 months was significantly lower (P less than 0.00001) among HIV-1-seropositive individuals (8%) than among the 75 HIV-1 seroconverters tested (25%), indicating that seroconversion to this neutralization domain occurs early during infection. AIDS and AIDS-related complex were diagnosed in 17% of the anti-Neu21 negatives and in 11% of the anti-Neu21 positives; this difference was not significant. The presence of HIV-1 antigen (29 versus 28%), the absence of antibodies to core proteins (45 versus 46%) and low CD4+ cell numbers (34 versus 40%) were not seen more frequently among anti-Neu21 negatives than among anti-Neu21 positives. These results argue against a role for antibodies to this LAV-1/HTLV-IIIB neutralization domain in protection against disease progression.

Adult↗