Patrick De Coster

Comparative correlations of HMPAO SPECT indices, neurological score, and stroke subtypes with clinical outcome in acute carotid infarcts.

BACKGROUND AND PURPOSE The prognostic value of single-photon emission computed tomography (SPECT) remains controversial. The aim of this study was to compare the prognostic value of stroke severity, stroke subtypes, and SPECT indices and to determine which predictive factors have an independent effect on clinical outcome. METHODS We studied 55 consecutive patients with acute (< 12 hours) carotid infarct within 36 hours of symptom onset with SPECT. Clinical presentation was assessed by the Canadian Neurological Scale and stroke subtypes. SPECT indices were the degree and size of hypoperfusion and crossed cerebellar diaschisis as assessed by a semiquantitative analysis. Outcome was evaluated by the functional status and mortality (Rankin Scale score at 1 month). RESULTS The Rankin Scale score correlated with the degree (r = .580; P < .00001) and size (r = .616; P < .00001) of hypoperfusion. The mean degree and size of hypoperfusion were significantly higher in patients with poor outcome. Crossed cerebellar diaschisis had no significant predictive value. Statistical analysis determined threshold values for the Canadian Neurological Scale score and the degree and size of hypoperfusion for the functional status and mortality. The degree and size of hypoperfusion had no higher performance than the Canadian Neurological Scale score. The negative predictive value was excellent for both clinical and SPECT indices. Multivariate analysis selected only the size of hypoperfusion as an independent predictor for the functional status (P = .004) and the Canadian Neurological Scale score for mortality (P = .009). CONCLUSIONS SPECT performed within 36 hours of onset predicts clinical outcome, but different clinical and SPECT indices with threshold values should be chosen according to the relevant outcome end point.

Coronary artery reperfusion in acute myocardial infarction: assessment by pre- and postintervention thallium-201 myocardial perfusion imaging.

In a randomized trial of intracoronary streptokinase (STK) therapy in acute myocardial infarction, 44 patients (21 control subjects and 23 patients treated with STK) underwent sequential thallium-201 planar imaging before angiography and after 4 hours (redistribution), 4 days and 6 weeks. Patients were classified according to the presence or absence of angiographic reperfusion of the infarct-related artery. The semiquantitative score of myocardial thallium uptake was expressed as percent of maximal defect score. Both in control and in STK-treated groups, thallium defect scores decreased over time, but this decrease was smaller in the control group (before angiography, 33 +/- 4%; redistribution, 29 +/- 4%; 4 days, 25 +/- 4%; and 6 weeks, 22 +/- 4%) than in the STK group (44 +/- 4%, 38 +/- 4%, 26 +/- 4% and 21 +/- 3%, respectively). In patients in whom reperfusion was achieved (20 STK-treated, 6 control subjects), a marked decrease in thallium score was observed (before angiography, 40 +/- 4%; redistribution, 32 +/- 4%; 4 days, 20 +/- 5%; and 6 weeks, 14 +/- 22%) compared with patients in whom reperfusion was not achieved (37 +/- 4%, 36 +/- 5%, 33 +/- 5% and 33 +/- 4%, respectively). These results indicate that serial thallium imaging is an accurate method of assessing changes in myocardial perfusion after acute myocardial infarction. Restoration of thallium uptake was observed after reperfusion of the infarct-related artery whether this recanalization was seen spontaneously or after successful thrombolysis.

Persisting Perfusion Defect in Transient Ischemic Attacks A New Clinically Useful Subgroup

BACKGROUND AND PURPOSE Cerebral infarction and prolonged regional hypoperfusion have been described in patients with transient ischemic attacks (TIAs). The aim of this study was to compare the sensitivity of single-photon emission CT (SPECT) with that of brain CT and to evaluate the clinical significance of differentiation of TIA patients with or without focal hypoperfusion. METHODS From a hospital-based population, we studied the SPECT and CT findings in 76 consecutive patients, without a stroke history, who presented with TIA in the carotid artery territory. The recorded variables were the time of SPECT, imaging (<36 or > or = 36 hours), clinical presentation, history of previous TIA(s), duration of the presenting attack (<2 or > or = 2 hours), vascular risk factors, and etiology. We used both visual and semiquantitative analyses for the SPECT evaluation. Acetazolamide challenge was not performed. RESULTS The overall SPECT sensitivity was 36% (27/76). When brain CT and SPECT were performed in the same patients, the SPECT sensitivity was significantly higher than that of CT (19/59 [32%] versus 8/59 [14%]; P=.007). The SPECT sensitivity was not dependent on the time of investigation, duration of attacks, history of TIA(s), or the clinical presentation. The vascular risk and etiologic factors were not significantly different between the patients with or without prolonged focal hypoperfusion. Logistic regression did not identify any variable to discriminate the two groups. CONCLUSIONS Despite its better sensitivity compared with CT, SPECT performed without the acetazolamide test provides no additional clinically useful information on the vascular risk factors and etiology in TIA patients.

Hemodynamic-effects of Felodipine At Rest and During Exercise in Exertional Angina-pectoris

To examine the antianginal effects of felodipine, a new calcium antagonist, 8 patients with coronary artery disease and exertional angina pectoris were studied. Hemodynamic measurements were made at rest, during submaximal exercise and during angina-limited exercise before and 30 minutes after oral administration of 0.1 mg/kg of felodipine. Angina pectoris was always prevented after the drug was given and the exercise intensity was increased until recurrence of angina (5 patients) or exhaustion (3 patients). Hemodynamic data were also recorded at this higher exercise capacity. At rest and during submaximal exercise, felodipine increased heart rate and decreased arterial blood pressure and systemic vascular resistance. The prevention of angina pectoris was accompanied by lower mean pulmonary capillary wedge pressure, systemic vascular resistance and ST-segment depression; the pressure-rate product was unchanged. The 20% greater exercise capacity after felodipine was attended by a 20% increase in maximal cardiac output, a 17% increase in maximal heart rate and a 13% increase in maximal pressure-rate product; the maximal arterial blood pressure and ST-segment abnormalities were unchanged and the systemic vascular resistance was lower. The relation between ST-segment depression and the pressure-rate product during exercise was favorably influenced by felodipine. Thus, felodipine is an active antianginal drug; its major mechanism of action is to lower the systemic vascular resistance. The data also suggest that it improves coronary blood flow during exercise.

Effect of exercise on plasma atrial natriuretic factor and cardiac function in men and women.

Abstract In order to provide an integrated view of the physiology of atrial natriuretic factor (ANF) during exercise, we studied changes of its plasma concentrations in 13 normal subjects (seven males, six females) during three graded exercise levels and two periods of recovery (5 and 30 min), concomitantly with an assessment of cardiac function and ventricular volumes by multigated radionuclide angiography. Mean ANF levels (± SEM) increased in all patients at the second (P < 0·002) and third (P < 0·002) exercise levels, and after 5‐min recovery (P < 0·01): in males from 16 ± 7 to 30 ± 11 pg ml‐1at the third level, in females from 27 ± 12 to 61 ± 33 pg ml‐1. Normal values were observed after 30‐min recovery. Even if mean ANF levels were all higher in females, this difference did not reach statistical significance (P= 0·06). Significant decreases of ventricular volumes, as well as increases of ejection fraction and rate pressure product, were noted during exercise and were similar in both sexes. The kinetics of plasma ANF concentrations, compared with the increase of rate pressure product, was characterized by a latency and a remanence in recovery. This remanence, also present in the changes of ventricular volumes, supports the hypothesis that other factor(s) like catecholamines might still exert their influence after the exercise stops.

Clinical Usefulness of Tc-99m Hmpao Spect Imaging To Map the Ischemic Lesion in Acute Stroke - a Reevaluation

To address the issue of whether single-photon emission computed tomography (SPECT) may add useful topographic information to neurologic examination in clinical practice, we compared technetium-99m hexamethyl propyleneamine oxime (HMPAO) SPECT and brain CT in 100 consecutive stroke patients involving the following clinical vascular territories: cortical middle cerebral artery (CMCA), 52; deep, 39; anterior cerebral artery(ACA), 3; posterior cerebral artery (PCA), 7. SPECT and CT sensitivity were calculated as the percentage of patients with respectively focal hypoperfusion or hypodensity related to the index event. The overall sensitivity of SPECT was not significantly different from CT (69 vs. 73%). The sensitivity of SPECT was not significantly dependent on the time of investigation (72% within 24 h, 50% on day 2, and 71% after day 3). Compared with CT, the sensitivity of SPECT was statistically significantly higher in CMCA infarcts (89 vs. 71%; p = 0.027) and lower in deep infarcts (40 vs. 69%; p = 0.024). The degree of hypoperfusion was significantly higher in cortical lesions than in deep lesions (27 vs. 9%; p < 0.001). Crossed cerebellar diaschisis seemed less frequent in patients with clinical lesion in the ACA and PCA territory (respectively 30 and 40%) and was not significantly different when the ischemic lesion involved the CMCA (56%) or deep territories (50%). No significant difference was found when SPECT took place within or after 48 h. Thus, the selective SPECT sensitivity according to the site of lesion and the degree of hypoperfusion may help to determine stroke subtypes in the acute phase. In contrast, in the subacute phase, SPECT is as sensitive as CT in mapping the ischemic lesion and should not be recommended for this purpose.

Effect of beta-adrenergic blockade on plasma atrial natriuretic factor and cardiac volumes during exercise in normal men.

Abstract Exercise stimulates the release of the atrial natriuretic factor (ANF). 1–3 The principal determinant of ANF release is atrial distension, 4 although adrenergic stimulation has also been implicated in the direct release of ANF. 5,6 Both of these mechanisms could account for the release of ANF during exercise. To elucidate the relative roles of these mechanisms, we determined the plasma ANF concentrations and cardiac volumes during exercise before and after β-adrenergic blockade with propranolol.

Exercise and Posture-Related Changes of Atrial Natriuretic Factor and Cardiac Function in Diabetes

To study whether the release of atrial natriuretic factor (ANF) was altered in diabetic cardiac autonomic neuropathy (CAN), we determined plasma ANF concentrations during exercise and changes of posture in three groups of age- and sex-matched subjects(9 healthy subjects, 7 diabetic patients with CAN, and 7 diabetic patients without CAN). During exercise, plasma ANF concentrations rose threefold (P < .001), and this increase was similar in the three groups. However, heart-rate response to exercise was impaired in the two groups of diabetic patients (P < .004 vs. healthy subjects) but was more severely impaired in patients with CAN (P < .03 vs. patients without CAN). In healthy subjects and patients without CAN, the increases of ANF during exercise correlated significantly with those of heart rate, systolic blood pressure, and rate-pressure product (P < .01). In patients with CAN, the correlation was found exclusively with heart rate (P < .01). An increase of ventricular ejection fraction occurred in all groups (P < .001) but without showing statistical differences between groups. After 30 min of standing, a similar postural drop of plasma ANF concentrations (P < .002) was observed in all subjects, reflecting preserved sympathetic control of vessels. In conclusion, exercise induces an increase of plasma ANF in diabetic patients with CAN. This increase, occurring similarly to healthy subjects, indicates that autonomic activation plays a minor role in ANF release during exercise. Impaired heart-rate response to exercise in patients without CAN suggests early damage of autonomic function, undetected by conventional rest tests.

Ejection fraction response to upright exercise in hypertension: relation to loading conditions and to contractility☆

The respective roles of peripheral and myocardial determinants of exercise ventricular performance were studied in 10 normal volunteers and in 9 mildly hypertensive patients without evidence of coronary disease. Hemodynamic measurements and equilibrium blood pool scintigraphy were simultaneously performed at rest and during maximal upright exercise. In hypertensive patients, mean systolic and diastolic blood pressure were, respectively, 199 +/- 23 and 102 +/- 12 mm Hg at rest, and 271 +/- 28 and 113 +/- 8 mm Hg at peak exercise. Ejection fraction response to exercise was normal (increase by more than 5%) in 4 hypertensive patients (normal hypertensive group: 63 +/- 4 to 77 +/- 6%) and in volunteers (65 +/- 3 to 78 +/- 4%) and abnormal in 5 hypertensive patients (abnormal hypertensive group: 66 +/- 6 to 58 +/- 10% at peak exercise). The abnormal response in the abnormal hypertensive group was not due to an inadequate decrease in systemic vascular resistance during exercise. By contrast, the ratio systolic blood pressure/end-systolic volume, an index of contractility, decreased by 2.3 +/- 4.9 in the abnormal hypertensive group, whereas it increased by 9.8 +/- 9.1 in the normal hypertensive group and by 7.3 +/- 2 in volunteers. Thus, abnormal exercise ejection fraction response in mild hypertension was not related to increased afterload but rather to intrinsic myocardial factors.

Exercise gated planar myocardial perfusion imaging using technetium-99m sestamibi for the diagnosis of coronary artery disease: an alternative to exercise tomographic imaging.

Single-photon emission tomography (SPET) using technetium-99m labelled myocardial tracers (e.g.99mTc-sestamibi) has become one of the most popular myocardial imaging methods for the diagnosis of coronary artery disease (CAD). This prospective study was designed to evaluate the diagnostic performance of99mTc-sestamibi exercise gated planar myocardial imaging by comparison with both visual and quantitative analyses of SPET. The study was conducted in 115 consecutive patients with known or suspected CAD, including 54 patients with a previous myocardial infarction (MI), referred for exercise testing prior to coronary angiography. Multi-gated planar imaging and SPET were performed after bicycle exercise. The end-diastolic (ED) and SPET images were visually scored (SVi). Myocardial uptake was quantitated on SPET slices using maximum count circumferential profiles (SQu) and defect extent was measured by comparison with gender-matched data sets obtained from 27 controls (<5% likelihood of CAD). CAD was defined as coronary artery stenosis >50% and/or regional wall motion abnormality. The cut-off criteria for positivity of the three procedures were determined from receiver operating characteristic (ROC) curves derived from the data of patients without previous MI. The area under the ROC curves was similar for ED, SVi and SQu. This was confirmed by the analysis of sensitivity performed using the ROC curve-derived cut-off criteria, in patients with or without previous MI. SVi was more sensitive than ED in identifying the diseased vessel(s) (ED: 41% vs SVi: 80%;P<0.0005) but ED was more specific in this respect (ED: 79% vs SVi: 61%;P<0.0005). We conclude that visual analysis of ED images obtained from gated99mTc-sestamibi stress planar imaging is a valuable alternative to SPET imaging for the diagnosis of CAD. SPET is, however, more accurate for the evaluation of the disease extent and localization and therefore remains the method of choice for the assessment of myocardial perfusion.