Biomedical subjects

P P Blockx

Publications and source records attributed to P P Blockx.

13 recordsLinked to original sources

PubMed1997

Adenosine technetium-99m sestamibi single-photon emission tomography for the assessment of jeopardized myocardium early after acute myocardial infarction. Paradoxical scintigraphic underestimation of jeopardized myocardium in patients with a severe infarct-related stenosis.

This study investigated the value of technetium-99m sestamibi scintigraphy in identifying patients at risk for post-infarct ischaemia (=jeopardized myocardium), especially within the reperfused infarct region. In 51 patients with a recent (<1 month) myocardial infarction, adenosine 99mTc-sestamibi single-photon emission tomography (SPET) and dobutamine stress echocardiography (DSE) were performed and correlated with the presence of significant coronary artery stenosis [% diameter stenosis (DS) >50%] on quantitative coronary angiography. Regional perfusion activity was analysed semi-quantitatively (score 0-4) on a 13-segment left ventricular model. DSE was used for the estimation of the infarct size (low-dose DSE) and for concomitant evaluation of ischaemia (high-dose DSE). A reversible perfusion defect within the infarct region was observed in 20 of the 37 patients with a significant infarct-related lesion (sensitivity of 54%) and only in one patient without a significant infarct-related lesion (specificity of 93%). Further analysis revealed that the scintigraphic assessment of jeopardized myocardium was fairly good in patients with a moderate (DS 51%-64%) infarct-related stenosis but was inadequate in patients with a severe (DS>/=65%) infarct-related stenosis (sensitivity of 80% vs 36%, P<0.01), while the echocardiographic detection of ischaemia was not influenced by stenosis severity (sensitivity of 73% in both subgroups). This scintigraphic underestimation of jeopardized myocardium was mainly related to a severely impaired myocardial perfusion under baseline conditions, as was evidenced by a significantly more severe rest perfusion score in the infarct region in patients with a severe stenosis as compared to those with a moderate stenosis (average score: 1.5+/-0.7 vs 2.1+/-0.6, P<0.01), while infarct size on echocardiography was similar for both subgroups. It may be concluded that early after an acute myocardial infarction, adenosine 99mTc-sestamibi SPET may underestimate reperfused but still jeopardized myocardium, particularly in patients with a severe infarct-related stenosis. In these patients the evaluation of the ischaemic burden on rest-stress scintigraphy is hampered by the presence of a severely impaired myocardial perfusion in resting conditions.

Adenosine↗

PubMed1996

Comparative study of rest technetium-99m sestamibi SPET and low-dose dobutamine stress echocardiography for the early assessment of myocardial viability after acute myocardial infarction: importance of the severity of the infarct-related stenosis.

Rest technetium-99m sestamibi single-photon emission tomography (SPET) has been shown to underestimate viability in some patients with chronic ischaemic myocardial dysfunction. The present study was designed to appraise the value of 99mTc-sestamibi as a viability tracer in patients with a recent myocardial infarction and to determine factors that might influence its accuracy in assessing infarct size. Therefore, rest 99mTc-sestamibi SPET, low-dose dobutamines stress echocardiography and quantitative coronary angiography were performed in 51 patients with a recent myocardial infarction. Perfusion activity and regional wall motion were scored semi-quantitatively using the same segmental division of the left ventricle. Assessment of 99mTc-sestamibi uptake as a marker of viability was performed by comparing a binary uptake score (viable=>50% vs necrotic =</=50% of the maximal tracer activity) with a binary wall motion classification during low-dose dobutamine infusion (viable=normal/hypokinetic vs necrotic=akinetic/dyskinetic). Infarct size, expressed as the number of segments with evidence of necrotic tissue, was significantly greater in the scintigraphic study than in the echocardiographic study (2.8+/-1.5 vs 2.2+/-1.3, P=0.006). This overestimation of infarct size by 99mTc-sestamibi was present only in patients with a severe infarct-related stenosis (% diameter stenosis >/=65%-100%) and particularly those with "late" reperfusion therapy (time delay >/=180 min). In patients without a severe infarct-related stenosis, 99mTc-sestamibi was able to accurately distinguish viable from necrotic segments. Thus, rest 99mTc-sestamibi scintigraphy early after acute myocardial infarction may underestimate residual viability within the infarct region, particularly in patients with low flow state coronary anatomy, as a result of a severe infarct-related stenosis and/or late reperfusion therapy.

Cardiotonic Agents↗

PubMed1996

Coronary flow reserve during coronary angioplasty in patients with a recent myocardial infarction: relation to stenosis and myocardial viability.

OBJECTIVES: In the present study, we examined post-stenotic coronary flow before and after percutaneous transluminal coronary angioplasty (PTCA) in patients with and without a recent myocardial infarction (MI) and related it to stenosis severity and residual viability. BACKGROUND: Post-stenotic coronary blood flow velocity reserve (CFVR) has been used with success to estimate functional stenosis severity in patients with stable angina. However, in patients with a recent MI, the impaired coronary vasodilator response of the reperfused myocardium may substantially alter the flow dynamics of the infarct-related artery. METHODS: Distal coronary flow velocities were recorded before and after PTCA in 36 patients at day 13 +/- 7 (mean +/- SD) after acute MI and in 38 patients without MI. The CFVR was assessed by the ratio of distal hyperemic to baseline average peak velocity, using a 0.014-in. Doppler guide wire. Stenosis severity was analyzed by quantitative coronary angiography, and infarct size was assessed scintigraphically. RESULTS: For similar angiographic stenosis severity, pre- and post-PTCA values of CFVR were significantly lower in patients with than without MI: 1.22 +/- 0.26 versus 1.50 +/- 0.45 before PTCA (p < 0.05) and 1.72 +/- 0.43 versus 2.21 +/- 0.74 after PTCA, respectively (p < 0.01). Although CFVR increased significantly (p < 0.0001) after angiographically successful PTCA in both study groups, abnormal CFVR (< or = 2.0) was still observed in 80% of patients with MI and in 44% of those without MI (MI vs. no MI, p = 0.001). Patients with an extensive infarction (relative infarct size > or = 50%) and those with a small infarction (relative infarct size < 50%) had comparable levels of post-PTCA CFVR (1.6 +/- 0.3 vs. 1.8 +/- 0.5, p = NS). Among a variety of factors, angiographic stenosis severity was the most important determinant of CFVR in both study groups. CONCLUSIONS: In patients with a recent MI, CFVR was significantly lower than in those without MI, both before and after PTCA. Besides the presence of this postreperfusion-related impairment of the coronary vasodilating response, CFVR was mainly influenced by stenosis severity and not by residual viability.

Adult↗

PubMed1996

Clinical outcome of patients with an uncomplicated myocardial infarction: effect of revascularization.

In 80 patients (pts) with an uncomplicated myocardial infarction (MI) the rate of major cardiac events (MACE) including cardiac death, non-fatal myocardial infarction and recurrent ischemia requiring hospitalization was prospectively assessed over a mean follow-up period of 17 +/- 9 months and related to clinical, angiographic and scintigraphic findings, the latter obtained from adenosine Tc-99m sestamibi SPECT imaging. Decision for revascularization was mainly based on angiographic data and was carried out in a total of 50 patients (angioplasty in 34 pts and cardiac surgery in 16 pts). The overall MACE rate was 24% with a mortality and myocardial infarction rate of 4% and 5%, respectively. Early (< 2 months) revascularization seemed to have a beneficial effect on clinical outcome as was suggested by the following findings: 1) Cardiac events (MACE) were not significantly different in patients with versus without revascularization (MACE 24% versus 23%) although the former constituted a subgroup at higher risk for ischemic events because of a more extensive coronary artery disease state. 2) In the subset of patients with at least one significant coronary artery stenosis the clinical outcome was significantly better in those who were revascularized than in those who underwent no revascularization (MACE 24% vs 47%, p < 0.05. Among a variety of factors, including the scintigraphic and angiographic extent of coronary artery disease and post-MI treatment strategy, multivariate analysis selected hypercholesterolemia (> 240 mg%) as the only independent predictor of MACE with a more than fourfold increase in risk for development of MACE. These data suggest that the natural history, especially the rate of recurrent ischemic events, can be favourably changed by an elective and early revascularization, strategically oriented by the results of the angio-graphic study. Furthermore, our data emphasized the deleterious role of hypercholesterolemia on clinical outcome in patients with a recent MI.

Angioplasty, Balloon, Coronary↗

PubMed1995

Adenosine technetium-99m sestamibi (SPECT) for the early assessment of jeopardized myocardium after acute myocardial infarction.

The purpose of this study was to evaluate the accuracy of adenosine Tc-99m sestamibi single photon emission computed tomography (SPECT) in the detection of jeopardized myocardium early after acute myocardial infarction. Coronary arteriography and myocardial scintigraphy were performed in 50 consecutive patients with an uncomplicated myocardial infarction. Myocardium was considered jeopardized if a significant infarct-related vessel stenosis (> 50% diameter stenosis) supplied an infarct area with residual viable tissue. Perfusion reversibility in the infarct region occurred in 25 patients (50%) and was almost solely observed in the presence of jeopardized myocardium. Non-reversible perfusion defects in the infarct region were found in patients without jeopardized myocardium. This subgroup consisted of either patients without significant vessel stenosis or patients without significant residual viability in the infarct region. Adenosine Tc-99m sestamibi SPECT had an accuracy of 88% for the detection of jeopardized myocardium. Side effects during adenosine infusion were frequently observed but well tolerated. These results suggest that adenosine Tc-99m sestamibi SPECT is an accurate non-invasive method for detecting jeopardized myocardium after acute myocardial infarction and may be a valuable non-invasive test for the early selection of patients at risk for future ischaemic events.

Adenosine↗

PubMed1990

Hepatic hydrothorax: report of two cases.

This paper describes two patients with liver cirrhosis presenting with right sided hydrothorax. The diagnosis of hepatic hydrothorax was confirmed by a radionuclide study using an intraperitoneal injection of radioactive 99mTc-tin-colloid, demonstrating the one-way transdiaphragmatic flow of fluid from the peritoneal to pleural cavities. Pleural taps, salt restriction and diuretics resulted in volume depletion and impaired renal function in the first patient. Medical therapy and a single thoracocentesis were successful in the other patient.

Aged↗

PubMed1984

Serum ferritin as a guide for iron stores in chronic hemodialysis patients.

The serum ferritin (SF) level was measured in 58 chronic hemodialysis (CHD) patients (46 living and 12 deceased subjects) and compared to bone marrow iron concentrations, cytological bone marrow iron stores (BMIS), and histological BMIS. In the 12 deceased subjects, liver iron concentrations, histological liver parenchymal, and Kupffer cell iron stores were also studied. The mean SF level of the whole group was 302 +/- 251 ng/ml (mean +/- SD). No close relationship was found between transferrin saturation and cytological BMIS. A high correlation was found between SF level and cytological BMIS (Spearman rank rs = 0.74). In the deceased CHD patients a close correlation was observed between histological parenchymal liver iron stores and histological Kupffer cell iron stores, but not between liver and bone marrow iron stores. A good correlation was found between SF levels and liver iron concentrations. It is concluded that in CHD patients SF levels are higher than in healthy controls, even in the absence of iron therapy (except in the form of blood transfusions); in some of these patients iron is disproportionately stored in the bone marrow and the liver. Although the level of BMIS cannot be estimated unequivocally from an SF measurement in every CHD patient, SF levels provide useful estimates of BMIS.

Adult↗

PubMed1984