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Biomedical subjects

P Dendale

Publications and source records attributed to P Dendale.

At least 19 recordsLinked to original sources
PubMed2000

Effect of exercise induced hyperlactatemia on the biodistribution and metabolism of iodine-123-15(p-iodophenyl)-3-R,S-methyl pentadecanoic acid in normal volunteers.

We have evaluated the biodistribution and metabolism of iodine-123-15-(p-iodophenyl)-3-R,S-methyl pentadecanoic acid (BMIPP) in the presence of increased lactate levels induced by short-term heavy exercise. Five healthy male subjects received 159 MBq (+/- 13 MBq) 123I-BMIPP at rest and a week later after they performed a maximal exercise test using a bicycle ergometer. Planar and tomographic images were obtained with a dual-head gamma camera up to 4 h after administration of the tracer. Multiple blood samples were taken at different time points for blood clearance, substrate concentration measurements and for HPLC analysis of metabolites. The exercise test did not alter plasma glucose and non-esterified fatty acid concentrations, but blood lactate increased from 1.12 mmol/l at rest to 9.26 mmol/l with maximal exercise. After exercise, BMIPP showed a significantly faster plasma clearance than at rest and the production of PIPA, the end metabolite of BMIPP oxidation, was reduced. Activity in the heart was similar after exercise and at rest on planar images 15 min after injection (4.83 +/- 0.50% ID vs 4.80 +/- 0.43% ID, P = NS), although the myocardium-to-cavity activity ratio, as determined on the SPET images 20 min after tracer injection, was slightly increased after the exercise test (4.20 +/- 0.63 vs 3.78 +/- 1.34 at rest, P = NS). Significantly increased activity was observed in a leg muscle region of interest after exercise (4.98 +/- 0.50% ID vs 3.93 +/- 0.44% ID at rest, P = 0.02). Between early and late images, tracer washout from the myocardium increased from 20.72% at rest to 36.72% after exercise (P < 0.05), but was unchanged for liver and leg muscles. The metabolic and physiological alterations induced by exercise do not degrade image quality of BMIPP scintigraphy. On the contrary, exercise-induced hyperlactatemia seems to enhance myocardium-to-cavity activity ratios on SPET images, although this effect does not reach statistical significance in this small group of normal subjects. These findings further support the robustness of BMIPP SPET in varied metabolic environments.

Adult↗
PubMed2000

Prediction of functional outcome by quantification of sestamibi and BMIPP after acute myocardial infarction.

Iodine-123 15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) can be used to image myocardial fatty acid regional distribution and utilisation with single-photon emission tomography (SPET). By visual analysis, a mismatching with regional uptake of BMIPP less than that of a perfusion tracer has been shown to predict myocardial viability and functional improvement after restoration of flow in patients with myocardial infarction. The current study aimed to evaluate a newly developed quantitative method of analysis of sestamibi and BMIPP uptake for the prediction of functional recovery after revascularization in patients with acute infarction. BMIPP and gated sestamibi SPET studies at rest were obtained before and >3 months after revascularization in 18 patients with recent infarction. A colour-coded polar map was generated from the comparison of sestamibi and BMIPP uptake. Depending on the relative distribution of the two tracers, different patterns of uptake were identified and their extent expressed as percentages of the surface of the whole left ventricle and of the three main coronary artery territories. At follow-up, recovery was defined as a > or =5% increase in ejection fraction compared with baseline. Receiver-operating characteristic curve analysis was performed to analyse the data. At baseline, significant correlations were found between ejection fraction and the % surface with decreased sestamibi or BMIPP uptake (r=-0.68, P= 0.001, and r=-0.72, P<0.0001, respectively). When combining both tracers, ejection fraction was significantly associated with the extent of myocardium showing decreased sestamibi uptake with lower BMIPP uptake (mismatching; r=-0.68, P=0.001). At follow-up, significant functional recovery was found in 13/18 patients. By ROC curve analysis, the optimal pattern of distribution predicting recovery was a mismatching with uptake of sestamibi <70% and uptake of BMIPP at least 10% lower. For this parameter, optimal cut-off of extent was 10% of the whole left ventricle surface (sensitivity 69%, specificity 80%, accuracy 72%) and 25% of the infarct-related arterial territory (sensitivity 77%, specificity 80%, accuracy 78%). The areas under the curve were 79% for the left ventricle surface and 72% for the individual arterial territories. These results suggest that in patients with acute infarction, quantitative analysis of sestamibi and BMIPP could offer an objective and reproducible method for estimating the severity of cardiac dysfunction and predicting the evolution of ejection fraction after revascularization.

Fatty Acids↗
PubMed2000

Venous pooling during nitrate-stimulated tilt testing in patients with vasovagal syncope.

AIMS: To investigate the importance of venous pooling and variation in venous tone during nitrate-stimulated tilt testing in patients. METHODS: Ten patients with a history of vasovagal syncope underwent an upright tilt test after an injection of 99mTc-labelled albumin. A gamma camera was positioned at the level of the lower legs. The patients were tilted to 90 degrees for 30 min or until symptoms developed. In those subjects who did not show any symptoms before the end of the 30-min period, isosorbide dinitrate (ISDN) 5 mg was given sublingually and the test was prolonged for a maximum of 15 min. RESULTS: Nine of 10 patients needed nitrate stimulation to develop symptoms, and one patient remained symptom free following ISDN administration. Measurement of radioactivity revealed no significant increase in calf volume after nitrate stimulation (the mean volume increase was 77% before ISDN stimulation and a further 0.9% afterwards). CONCLUSIONS: The higher sensitivity for vasovagal syncope during upright tilt testing after administration of sublingual ISDN is not due to an increase in venous pooling in the lower extremities.

Administration, Sublingual↗
PubMed2000

Six months clinical, angiographic, and IVUS follow-up after PTFE graft stent implantation in native coronary arteries.

INTRODUCTION: Restenosis remains a problem even after stent implantation. An important breakthrough could be the use of graft stents, functioning as a mechanical barrier between the blood flow and the vessel wall, and possibly inducing less restenosis by more limited hyperplasia and minimal transgraft tissue penetration. OBJECTIVE: To assess the acute and 6 months clinical, angiographic and IVUS results of a new balloon expandable coronary polytetrafluoroethylene (PTFE) graft stent (Jomed). METHOD: Ten patients with a short (< or = 15 mm length) de novo proximal stenosis in a large (> or = 3 mm diameter) coronary artery were treated by elective implantation of a graft stent (19 mm stent, 15 mm graft). Clinical assessment, quantitative coronary angiography (QCA) and intracoronary ultrasound (IVUS) were performed before, immediately after and 6 months after implantation. A stress test was also done at 6 months. RESULTS: The coronary arteries treated were: RCA in 7 patients, LCX in 2 patients, LAD in 1 patient. Mean balloon size was 3.7 mm diameter, and mean inflation pressure was 18 atm (min. 12, max. 23). Additional stenting was needed in 3 patients. Two patients showed a minimal rise in CK (< 250 IU/l) and 1 patient needed a transfusion. No patient experienced a (sub)acute nor late thrombosis. As shown in the table, no restenosis was seen in the body of the graft stent. In 2 patients a restenosis was detected in the proximal and/or distal parts of the stent which are not covered by the graft. In 1 patient a restenosis was found outside the stent. All patients remained asymptomatic with a negative stress test at 6 months follow-up (FU). [table in text] CONCLUSIONS: A graft stent could indeed reduce the restenosis rate after stenting, in the part of the stent covered by the graft, but the uncovered distal and proximal parts are the weak points in this type of stent. For this reason, technical ameliorations in the construction of this graft stent are needed, e.g. a complete coverage of the stent by the PTFE graft and less rigidity of the stent causing reduced vessel trauma at the edges of the stent during implantation.

Adult↗
PubMed1999

Quantitative assessment of regional dysfunction from gated single photon emission tomography myocardial perfusion studies: a non-segmental approach.

We present a modified (non-segmental) method for quantification of regional left ventricular dysfunction using gated myocardial perfusion SPET. Gated SPET is increasingly used to obtain complementary information on local perfusion and to assess the relevance of deficits in segmental count densities (attenuation vs perfusion deficit). The non-segmental approach was motivated by a hypothetical limitation regarding the validity of commonly used methods of quantitative wall thickening (WT) analysis. These methods are all based on segmental analysis, which could cause underestimation of 'true' contractile dysfunction in perfusion defects that do not have a strict segmental distribution. SPET images gated in eight time bins 60 min after the injection of 740 MBq 99Tcm-tetrofosmin or 99Tcm-sestamibi were recorded on a triple-headed camera in 20 normal subjects and in 16 patients within 2 weeks and again 3 months after myocardial infarction. Normal limits of wall thickening, calculated from pooled wall thickening profiles obtained in normal subjects, were used to identify and quantify areas with abnormal wall thickening in patients with coronary artery disease. The method was validated against data obtained from contrast ventriculography (CVG) and tested for reproducibility. The reproducibility of the method was excellent: r = 0.98 (WTsev measure 1 = 1.03WTsev measure 2 - 0.01). The localization of wall thickening abnormalities detected by gated SPET correlated well with the localization of regions with abnormal wall motion (WM) identified by CVG. The severity of the regional myocardial dysfunction assessed by gated SPET was closely correlated with the severity of the regional myocardial dysfunction derived from CVG: r = 0.85 (WMsev = 2.55WTsev + 2.30). Furthermore, a good correlation between the total wall thickening severity score and the global left ventricular ejection fraction (LVEF) was observed early and late after myocardial infarction: r = 0.80 (WTsev = -0.4LVEF + 0.46). We conclude that quantitative analysis of regional wall thickening assessed from gated SPET myocardial perfusion scintigraphy is a reliable parameter for regional ventricular function. Categorizing wall thickening abnormalities quantitatively may be helpful in assessing small changes in regional function that may occur between sequential gated SPET images.

Adult↗
PubMed1999

Intravenous nitrates for pharmacological stimulation during head-up tilt testing in patients with suspected vasovagal syncope and healthy controls.

Nitrates may be used for pharmacological stimulation during tilt testing for the diagnosis of vasovagal syncope. In this study we assessed the diagnostic value of intravenous nitrates during tilt testing in patients with a typical history of vasovagal syncope. Twenty patients and 23 controls were tilted at 700 for a maximum duration of 30 minutes. After a 10-minute baseline supine phase, the test started with a continuous nitrate infusion at 1 microg/kg/min and increased every 5 minutes by 1 microg/kg/min, to a maximum of 6 microg/kg/min at the end of the test. The test was ended if the subjects developed a positive response (syncope or presyncope). Nineteen patients (95%) and 17 (74%) of the controls had a positive response. At test end sensitivity was 95%, but specificity was 26% and accuracy was 58%. Receiver operator characteristics (ROC) analysis revealed a maximum accuracy of 79% at 18 minutes, with a sensitivity of 80% and a specificity of 78%. Intravenous nitrates during tilt testing in patients with typical clinical criteria of vasovagal syncope is highly effective in provoking vasovagal syncope. Based on the ROC analysis, a maximum accuracy of 79% was attained at 18 minutes (at a dose of 4 microg/kg/min), suggesting a good diagnostic performance when tilt duration is limited to this point. A positive result requiring more than 18 minutes of stimulated tilting should be interpreted with caution, due to the accompanying considerable decrease of specificity.

Adult↗
PubMed1999

Prinzmetal's variant angina: three case reports and a review of the literature.

Prinzmetal's variant angina is a rare entity. When angina-like symptoms occur at rest, mostly at a specific hour in the early morning, together with transient ST segment elevations and angiographically normal arteries, provocative tests with ergonovine or acetylcholine should be performed. Endothelial dysfunction, a strong thrombotic tendency, an increased platelet aggregation together with changes in autonomic tone can trigger coronary vasospasms. Once treated with calcium antagonists and nitrates the prognosis is excellent and severe complications such as arrhythmias, myocardial infarction or sudden death are extremely rare. Coronary stenting can be useful for refractory coronary spasm, CABG can be used for important coronary atherosclerosis. This review is illustrated with three typical presentations of variant angina: a myocardial infarction without significant organic coronary atherosclerosis, an ergonovine-induced coronary spasm with a non-significant coronary lesion and a multivessel spasm complicated by ventricular arrhythmia. All these three patients became asymptomatic after a treatment with calcium antagonists and nitrates.

Angina Pectoris, Variant↗
PubMed1998

Autonomic testing in patients with chronic fatigue syndrome.

The purpose of this study was to determine whether chronic fatigue syndrome (CFS) patients show autonomic dysfunction at the cardiac level and if so, to discover whether these abnormalities explain the fatiguability and/or other symptoms in CFS. The study population consisted of 21 CFS patients (Centers for Disease Control and Prevention [CDC] criteria, 1988) and 13 age- and sex-matched healthy controls. The autonomic testing consisted of: (1) postural challenge: registration of heart rate and blood pressure (BP) and heart rate variability in supine and in upright position (tilted to 70 degrees); (2) Valsalva maneuver; (3) handgrip test; (4) cold pressor test; and (5) heart rate response to deep breathing. Statistical analysis was performed using the Mann Whitney rank sum test; results of the test were considered significant at the 0.05 level. After tilting heart rate was significantly higher in CFS patients compared with healthy controls (mean CFS = 88.9 beats/min vs control = 77.9 beats/min; P <0.01). Low frequency power after tilting was significantly higher in CFS patients compared with controls (mean CFS = 0.603 vs control = 0.428; P = 0.02). There was a trend toward an increased heart rate during the cold pressor test. Other parameters did not differ between the CFS and control populations. The observed changes point toward a sympathetic overactivity in CFS patients when they are exposed to stress. Parasympathetic abnormalities could not be observed. Therefore, our findings provide no real explanation for the fatigue and intolerance to physical exertion in these patients.

Adult↗
PubMed1998

Contrast enhanced and functional magnetic resonance imaging for the detection of viable myocardium after infarction.

PURPOSE: Viable myocardium after acute myocardial infarction may be characterized by magnetic resonance imaging (MRI) either by demonstration of recovery of wall motion under dobutamine stress or by perfusion patterns after contrast medium administration. This study examines the relation between the two techniques. MATERIALS AND METHODS: Gradient-echo MRI at rest and under low-dose dobutamine stress was performed in 28 patients within the first 2 weeks after acute myocardial infarction. In addition, spin-echo MRI was performed after gadolinium-DOTA administration. Wall motion at rest and under stress was scored to assess the contractile reserve of the infarct regions. Infarct enhancement patterns were classified as subendocardial, transmural, or as a doughnut pattern. RESULT: Subendocardial or absent infarct enhancement was related to functional recovery under stress in 31 of 37 infarct segments. Transmural infarct enhancement was correlated with the absence of functional recovery in 10 of 17 infarct segments (p < 0.002), indicating nonviability. The doughnut pattern was exclusively associated with the absence of viability (five of five). CONCLUSION: Contrast enhancement patterns are related to residual myocardial viability.

Aged↗
PubMed1998

MR of the heart under pharmacologic stress.

Magnetic resonance imaging is one method for assessing cardiac function and perfusion at rest and under stress conditions. In this article, the potential of stress magnetic resonance imaging for evaluating ischemic heart disease is reviewed, and technical aspects of some developments that may contribute to comprehensive magnetic resonance imaging assessment of heart disease under rest and stress are discussed.

Cardiotonic Agents↗
PubMed1998

Patent foramen ovale and decompression sickness in sports divers.

Patency of the foramen ovale (PFO) may be a cause of unexplained decompression sickness (DCS) in sports divers. To assess the relationship between PFO and DCS, a case-control study was undertaken in a population of Belgian sports divers. Thirty-seven divers who suffered from neurological DCS were compared with matched control divers who never had DCS. All divers were investigated with transesophageal contrast echocardiography for the presence of PFO. PFO size was semiquantified on the basis of the amount of contrast passage. Divers with DCS with lesions localized in the high cervical spinal cord, cerebellum, inner ear organs, or cerebrum had a significantly higher prevalence of PFO than divers with DCS localizations in the lower spinal cord. For unexplained DCS (DCS without commission of any diving procedural errors), this difference was significant for large PFOs only. We conclude that PFO plays a significant role in the occurrence of unexplained cerebral DCS, but not of spinal DCS. We further stress the importance of standardization and semiquantification of future PFO studies that use transesophageal contrast echocardiography.

Adult↗
PubMed1998

Coronary NIR stent implantation for refractory variant angina.

A 44-year-old woman with severe variant angina refractory to maximal medical therapy and at risk of sudden death was successfully treated by a NIR stent implantation on a moderate lesion of LAD. Six months later she was asymptomatic, without in-stent restenosis. This procedure represents an alternative treatment for patients with refractory vasospastic angina.

Adult↗
PubMed1997

Sublingual nitrates during head-up tilt testing for the diagnosis of vasovagal syncope.

Pharmacologic stimulation during head-up tilt test (HUT) is used to increase the diagnostic yield of the test to detect vasovagal syncope. Reported lack of specificity of stimulation with intravenous isoproterenol has made a pharmacologic alternative desirable. Because nitrates are known to cause syncope of a vasovagal origin, we administered sublingual nitrates after classic tilt test in 32 patients with a history of typical vasovagal syncope and 20 healthy volunteers to assess the sensitivity, specificity, and accuracy of this new HUT technique. During the classic HUT four (13%) patients had syncope; after administration of sublingual nitrates, this number increased to 28 (87%). In the control group no subject had syncope during classic HUT, whereas during nitrate administration six (30%) had syncope. Sublingual nitrate stimulated HUT revealed a maximum accuracy of 83% at a cutoff point of 11 minutes, giving a sensitivity of 81% and specificity of 85%. Sublingual nitrate administration increased the accuracy of HUT in diagnosing vasovagal syncope in patients with a history of typical vasovagal syncope.

Administration, Sublingual↗
PubMed1997

Physical fatigability and exercise capacity in chronic fatigue syndrome: association with disability, somatization and psychopathology.

Physical fatigability and avoidance of physically demanding tasks in chronic fatigue syndrome (CFS) were assessed by the achievement or nonachievement of 85% of age-predicted maximal heart rate (target heart rate, THR) during incremental exercise. The association with functional status impairment, somatization, and psychopathology was examined. A statistically significant association was demonstrated between this physical fatigability variable and impairment, and a trend was found for an association with somatization. No association was demonstrated with psychopathology. These results are in accordance with the cognitive-behavioral model of CFS, suggesting a major contribution of avoidance behavior to functional status impairment; however, neither anxiety nor depression seem to be involved in the avoidance behavior. Aerobic work capacity was compared between CFS and healthy controls achieving THR. Physical deconditioning with early involvement of anaerobic metabolism was demonstrated in this CFS subgroup. Half of the CFS patients who did not achieve THR did not reach the anaerobic threshold. This finding argues against an association in CFS between avoidance of physically demanding tasks and early anaerobic metabolism during effort.

Adult↗