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Biomedical subjects

H Sochor

Publications and source records attributed to H Sochor.

At least 55 records · Page 3Linked to original sources
PubMed1986

Role of beta-endorphins in silent myocardial ischemia.

The reason for the absence of pain perception in silent myocardial ischemia is unknown. A role of increased endorphinic activity in patients with silent ischemia has been postulated. To further investigate this hypothesis, 10 men with documented coronary artery disease and previous positive electrocardiographic findings during exercise without anginal pain were studied. Six healthy volunteers served as control subjects. The protocol included 2 bicycle exercise tests, the first test serving as baseline and the second performed after administration of naloxone, a specific opiate antagonist. Plasma beta-endorphin levels were measured by radioimmunoassay in both tests at rest, at peak exercise level and after recovery. All patients underwent thallium-201 scintigraphy after coronary vasodilation to provide an additional independent marker of ischemia. All patients showed stress-induced reversible perfusion abnormalities. No patient reported pain after naloxone application. Exercise duration, blood pressure and heart rate were not significantly altered by naloxone. Plasma beta-endorphin levels ranged from 18 +/- 6 pg/100 microliters (mean +/- standard deviation) at rest to 22 +/- 6 pg/100 microliters during exercise in the patient group and from 20 +/- 5 to 27 +/- 9 pg/100 microliters in the control subjects. Thus, there was no significant increase of plasma beta-endorphins during exercise or after naloxone administration, nor was there any difference observed between patients and control group. These data support the view that endorphinic activity does not play an essential role in the pathophysiology of silent myocardial ischemia.

Blood Pressure↗
PubMed1986

Studies of fatty acid metabolism with positron emission tomography in patients with cardiomyopathy.

Positron emission tomography (PET) permits in vivo as well as noninvasive study of fatty acid metabolism. Parameters of 11C-palmitate kinetics relate to the oxidation of fatty acids, and palmitic acid uptake is impaired in patients with coronary disease and cardiomyopathy. Normal myocardium shows homogeneous fatty acid metabolism and can resort to alternate substrates. Diseased myocardium exhibits regional heterogeneity in fatty acid uptake and utilization. In patients with cardiomyopathy, distinct patterns of fatty acid metabolism can be observed following changes of substrate availability by application of an oral glucose load. This intervention also enhances the heterogeneity of 11C-palmitic acid (CPA) uptake and clearance. Thus, PET studies with CPA permit the noninvasive demonstration of effects on substrate availability and may help to characterize patients with ventricular dysfunction on the biochemical level.

Adult↗
PubMed1986

Effects of substrate availability on myocardial C-11 palmitate kinetics by positron emission tomography in normal subjects and patients with ventricular dysfunction.

The possibility of demonstrating noninvasively with C-11 palmitate and positron emission tomography (PET) changes in myocardial substrate metabolism in normal and diseased human myocardium in response to altered substrate availability in blood and disease-related abnormalities was examined in five normal volunteers and 16 patients with ventricular dysfunction. C-11 palmitate injection and serial PET imaging were performed after an overnight fast (control period) and again 2 hours later after oral glucose (50 gm). Myocardial C-11 time-activity curves from serial PET images revealed a biexponential clearance pattern. An early rapid phase, defined by relative size and clearance half-time, reflects C-11 palmitate oxidation and the late slow phase tracer deposition in the endogenous lipid pool. During the control period, the tracer fraction entering the early rapid phase averaged 47 +/- 13% (SD) in normal subjects and 45 +/- 12% in patients. Corresponding clearance half-times were 19 +/- 7 and 20 +/- 5 minutes, respectively. Heart rate and blood pressure remained unchanged after glucose, but plasma glucose levels rose by 72.5% in normal subjects and by 98.9% in patients, while free fatty acid levels fell by 72% and 42% (p less than 0.001), respectively. In normal subjects, the tracer fraction in the early rapid phase fell by 43% (p less than 0.005) and the clearance half-time increased by 46% (p less than 0.01). In patients, the response of C-11 palmitate tissue kinetics to glucose was variable. In nine patients, it was similar to that in normal subjects while in the other seven patients a "paradoxic" response occurred. The tracer fraction entering the rapid clearance phase increased after glucose by 30% (p less than 0.05) associated with a 36% (p less than 0.05) decline in clearance half-times. The paradoxic response was unrelated to disease etiology or plasma substrate levels but occurred mostly in left ventricles with more severely depressed function. Thus, PET and C-11 palmitate allow the noninvasive demonstration of the known response of substrate metabolism of the human heart to altered substrate availability. Glucose administration in fasted humans serves as a provocative test of substrate regulation which can be abnormal in myocardial disease and can be demonstrated noninvasively.

Adult↗
PubMed1986

Identification of impaired metabolic reserve by atrial pacing in patients with significant coronary artery stenosis.

We investigated myocardial 11C-palmitate clearance kinetics at a resting heart rate (control) and during pacing using positron-emission tomography in 10 patients with significant coronary artery stenosis (greater than 70%) and evidence of exercise-induced ischemia. Serial 11C-palmitate images acquired at control and during pacing revealed biexponential myocardial 11C clearance both in myocardium supplied by a stenotic coronary artery (myocardium "at risk") and in myocardium supplied by a normal coronary artery (normal myocardium). At control, the average rate of myocardial 11C clearance from the early rapid curve component (the clearance half-time) was similar in normal myocardium and in that at risk (22.2 +/- 5.2 vs 21.0 +/- 5.4 min, NS), as was the amount of myocardial 11C activity at the end of the early rapid phase (residual fraction 56.3 +/- 7.2% vs 54.7 +/- 7.3%, NS). Thus, myocardial clearance was homogeneous at control, suggesting a similar rate and amount of 11C-palmitate oxidation in normal myocardium and in that at risk. Pacing shortened clearance half-times and decreased residual fraction in both normal myocardium and that at risk compared with control. However, clearance half-times were 17% longer and residual fractions 14% higher in myocardium at risk compared with normal myocardium (p less than .005 and p less than .01, respectively). Therefore, during pacing myocardial 11C clearance became heterogeneous, suggesting impaired 11C-palmitate oxidation in myocardium at risk compared with normal myocardium. Increased substrate utilization in response to increased workload can be thought of as a measure of metabolic reserve. Our data suggest metabolic reserve for free fatty acid oxidation is impaired in myocardium supplied by a significantly stenosed coronary artery and that this impairment can be detected by analysis of myocardial 11C-palmitate clearance.

Adult↗
PubMed1985

[Hemofiltration in chronic heart failure].

30 patients with severe congestive heart failure (NYHA IV) unresponsive to medical management were treated by continuous hemofiltration (CHF). 57% of patients received arteriovenous CHF and 43% of patients venovenous, machine assisted CHF over 95 +/- 31 hours. A reduction of body edemas was achieved. The removal of body fluid by CHF between 2 and 40 kg led to a reduction of body edemas and short-term clinical improvement. Furthermore CHF treatment induced hemodynamic improvement with a reduction of central venous pressure (18 +/- 6 cm H2O pre CHF vs 8 +/- 4 cm H2O post CHF p less than 0.01) and a reduction of left ventricular filling pressure (22 +/- 6 mm Hg vs 14 +/- 5 mm Hg, p less than 0.01), while the left ventricular ejection fraction remained unchanged. Patients with low serum sodium levels (less than 132 mval/l) benefited most. While 28/30 of patients has short-term clinical improvement between 2 and 8 weeks, 38% of patients had long-term benefits.

Adult↗
PubMed1984

Reduction of infarct size induced by pressure-controlled intermittent coronary sinus occlusion.

The effect of pressure-controlled intermittent coronary sinus (CS) occlusion on myocardial infarction (MI) size was evaluated. A device for this purpose was developed that consisted of a balloon catheter and pump system that produced controlled, intermittent occlusion of the CS and used CS pressure as a feedback to determine the duration of occlusion. It was hypothesized that proper selection of occlusion and non-occlusion times would both facilitate improved retrograde flow to ischemic areas and allow for more complete venous washout of metabolites. In 13 treated dogs and 12 control dogs before treatment, myocardium at risk of MI was estimated by injection of technetium-labeled microspheres. Intermittent CS occlusion was then begun, 15 minutes after coronary artery occlusion, and continued until termination of the experiment 6 hours later. Postmortem determination of infarct size was performed using the triphenyltetrazolium chloride staining technique. Intermittent CS occlusion begun 15 minutes after coronary artery occlusion and continued for 6 hours resulted in a 45% average reduction in MI size (p less than 0.001). During CS occlusion, the sinus systolic mean pressure increased from 10 to 44 mm Hg, while the distal coronary artery mean pressure increased by an average of 36% (from 22 to 30 mm Hg, p less than 0.05). These results suggest intermittent occlusion may be an effective treatment for evolving MI. This therapy, used alone or combined with other therapies (e.g., administration of pharmacologic agents), appears to have great clinical potential.

Animals↗
PubMed1984

Radionuclide imaging after coronary vasodilation: myocardial scintigraphy with thallium-201 and radionuclide angiography after administration of dipyridamole.

Tl-201 imaging was performed in 194 patients who had undergone coronary angiography which had demonstrated coronary artery disease in 149 and normal coronary vessels in 45.91 patients had had previous myocardial infarction. Sensitivity for dipyridamole stress imaging was 92% for all 149 patients. 79% for the patients without previous infarction. Specificity was 81%. In a subgroup of 40 patients (32 patients with reversible Tl-201 defects and 8 normals), an additional dipyridamole wall motion study was performed in order to evaluate the correlation of Tl-201 perfusion abnormalities and ventricular function after dipyridamole. Only 19% of the patients had a dipyridamole-induced drop of global left ventricular ejection fraction, 31% showed dipyridamole-induced wall motion abnormalities; the predictability of specific vessel involvement by regional wall motion and regional ejection fraction assessment was 26% as compared with 70% for thallium imaging. Tl-201 perfusion defects after dipyridamole administration can also occur independent of ischaemia-induced changes in global and regional ventricular function. Coronary vasodilation with dipyridamole using Tl-201 imaging is a reliable alternative method in patients with coronary artery disease with an accuracy comparable to exercise studies with the advantage of not necessarily needing ischaemia as an endpoint of the test.

Cineangiography↗
PubMed1983

[Emission-computed tomography of the myocardium with the 7-pinhole collimator].

89 patients (78 with coronary artery disease, 11 normals) were studied comparatively with T1-201 planar myocardial scintigraphy and 7-pinhole emission tomography with a mobile gamma-camera. In 46 patients stress studies were performed, the other studies were performed as resting protocols. In 13 patients a correlation of scintigraphically determined infarct size calculated from the T1-201 tomograms with CK and CK-MB values (maximum values) in the acute infarction period was performed. 17 patients having undergone intracoronary streptolysis were studied to investigate the effect of this intervention. In patients without previous myocardial infarction (n = 35) sensitivity of 7-pinhole tomography was significantly superior over planar reading of images (83% for qualitative evaluation, 91% for quantitative analysis). In patients with previous myocardial infarction (n = 26) comparative sensitivities were not significantly different, although slightly higher, nevertheless the fraction of questionable findings was reduced from 9 to 4%, furthermore in 31% an additional information concerning size or localization could be obtained from the tomograms. Predictive diagnostic accuracy was highest for quantitative 7-pinhole tomography (91%) but not significantly different from qualitative tomography but higher than for planar imaging. Specificities of all methods were comparable. In patients during the acute phase of myocardial infarction a significant correlation (r = 0.76 for CK, r = 0.78 for CK-MB, p less than 0.01) was obtained with enzymatic markers of infarct size. In the group after intracoronary streptolysis 7-pinhole tomography was able to demonstrate a quantitative reduction of thallium infarct size in patients after successful lysis (23.5% vs 48.7%, p less than 0.01) although absolute quantitation is not possible with thallium-201 due to inherent biological limitations. Emission tomography using 7-pinhole collimation leads to an improvement of diagnostic accuracy in all patients with reversible ischemia and helps for better delineation of size and localization of infarct areas and could help in the assessment of interventional effects, as after intracoronary streptolysis.

Adult↗
PubMed1982

[Hemodynamics of congestive cardiomyopathy].

202 patients with congestive cardiomyopathy have been classified according to their hemodynamic, angiographic, echocardiographic and scintigraphic findings: 72 patients were in the late stage (LS), 103 patients in an early stage (ES) and 17 patients showed a latent form of the disease. 48% of the hemodynamic ES were found to be clinically in stage IV NYHA and 53% of ES fell in class III. 40% of the patients with LS showed a stationary clinical course whereas 46% could improve their classification by one grade. The mortality in hemodynamic LS was 46% within an interval of 18 +/- 14 months after the diagnosis. In ES 64% showed a stable clinical course, where a 22% were deteriorating. Mortality in this group was 10%. Sensitivity and specificity of echocardiography (93 vs 80%) and radionuclide methods (80 vs 71%) were quite good in the late stage whereas in ES specificity was only 71% vs 80%. There was a discrepancy between the degree of myocardial impairment and clinical symptoms in the late stage whereas in the early stage there was no correlation between exercise capacity and LV-hemodynamics. Non-invasive methods allow the hemodynamic evaluation of the disease; invasive methods are required for clarification of diagnosis or establishing prognosis.

Adult↗
PubMed1982

[Selective thrombolysis in acute myocardial infarction: evaluation of functional result by metabolic studies and perfusion imaging (author's transl)].

The effects of selective thrombolysis with intra-coronary streptokinase in regard to myocardial protection are still debated. In 25 patients with acute myocardial infarction we evaluated regional metabolism with 123 radio-iodinated heptadecanoic acid and segmental 201 thallium scintigraphy in the distribution of the recanalized coronary vessel. Lysis was successful in 11/16 occlusions of LAD-, 4/7 RCA- and 1/2 CX-vessels. In this group (A) the average defect size on TI-scintigrams was 19 +/- 6% 24 hours after the intervention, whereas unsuccessful recanalisation (group B) resulted in a defect size of 38 +/- 7% (p less than 0.01). There was good concordance between thallium defect size and fatty acid metabolism in group B. However, in group A 6 of 11 patients showed significantly smaller fatty aid accumulation than the thallium defect size reflected. These data suggest that successful reperfusion does result in protection of myocardium in the majority of infarct patients reflected in the smaller TI infarct size. Successful reperfusion, however, does not always immediately restore metabolic dysfunction. This discrepancy will have to be analyzed by further follow-up studies of these patients.

Coronary Vessels↗
PubMed1982

[Experimental model for determination of an "in vivo" area at risk accounting for the quantity and distribution of collateral flow (author's transl)].

To determine the influence of interventions on infarct size numerous studies have attempted a comparison between treatment and control groups. This has been complicated by the great variability in the quantity of necrosis due to the differences in coronary bed size and collateral flow. An experimental model is presented in which it is possible to determine an "area at risk of infarction" at several time points during the evolution of the infarct. This model allows to estimate infarct size that may be expected under the present conditions, prior to interventions, early, in vivo and in the same experiment. It is possible to quantitate topographically changes in collateral flow and to investigate the effect of intervention in the same experiment. We found a correlation of life-threatening arrhythmias including ventricular fibrillation with the size of the "myocardium at risk of infarction" and with the size of the infarcts measured post mortem. Several beneficial interventions were studied.

Animals↗
PubMed1981

Noninvasive rCBF determination by 133XE-inhalation with the gamma camera and functional imaging of wash-in and wash-out. A new combined approach for rCBE measurements in patients with cerebrovascular disease.

In 47 patients with cerebrovascular disease (CVD) a noninvasive determination of global and regional cerebral blood flow (CBF) was performed with the gamma camera. A new approach was developed for region definition and for evaluation of the "start-fit-time' as the point of minimal contamination of the recorded data by extracerebral scatter and recirculation using the region of interest (ROI)-technique in the camera field of view. In comparison with the results of probe measurement of end-tidal exhalation air no significant differences were seen and values obtained were well in the range reported by other authors. Initial slope (IS), gray matter flow (F1) and CBF-15 were used as quantitative parameters and were able to distinguish significantly (P less than 0.01) between normals, patients with mild CVD, and severe CVD. Intraexamination variation coefficient (VC) was 5%, interexamination VC was 8%. Functional, parametric images of wash-in for easier ROI-definition and judgement of isotope supply and of wash-out were generated by a computer analysis and were found to be sensitive indicators for arterial blood supply and wash-out values city. Thus it was possible to recalculate regional flow values in focal areas exactly corresponding to abnormalities seen on the functional images. So the regional information of functional images can be combined with the quantitative data in selectable areas. By tis noninvasive, easily performed method focal neurological deficits can be evaluated with high accuracy with conventional nucleus medicine equipment.

Cerebrovascular Circulation↗
PubMed1979

Radionuclide assessment of cardiac performance and myocardial perfusion in congestive cardiomyopathies.

To determine the reliability of radionuclide techniques in the diagnosis of congestive cardiomyopathy (COCM), the function of the right ventricle (RV) and left ventricle (LV) was evaluated in 32 patients with COCM and 21 normal subjects using radionuclide angiography (first pass and gated blood pool scan) combined with quantitative 201 thallium (Tl) myocardial perfusion imaging. In COCM parameters of RV and LV performance were significantly reduced (p less than 0.01); regional wall motion analysis revealed a reduced radial shortening ability (p less than 0.05). 201 Tl distribution within the myocardium was not different between COCM and N; however, segmental 201Tl-uptake was significantly reduced (p less than 0.01). RV free wall was visualized on 201Tl scan in 80% of patients with COCM. There was no correlation between RV free wall visualization and RV hemodynamics. Thus these scintigraphic aspects provide an atraumatic and sensitive technique for the evaluation of patients with COCM.

Adult↗
PubMed1979

Assessment of left ventricular performance and myocardial viability using quantitative radioisotope techniques.

The diagnostic value of a combined radionuclide technique was compared with conventional angiocardiographic techniques in 60 patients with coronary artery disease. Quantitative 201Tl myocardial imaging combined with radionuclide angiocardiography using 99mTc-HSA provided a safe and accurate method for the assessment of left ventricular performance. The defects on the 201Tl images correlated with the severity of asynergy seen on the contrast ventriculogram. Static imaging alone distinguished hypokinetic from akinetic or dyskinetic areas. However, using both tracer techniques, akinesis could bedistinguished from dyskinesis. In patients with disturbed left ventricular function, cardiac transit times correlated with haemodynamic changes, and left ventricular ejection fraction was the most sensitive index. Thus, this combined radionuclide approach provides data for the evaluation of overall and regional wall function. A major advantage of this non-invasive auantitative technique is its applicability to the critically ill patient at the bedside.

Adult↗
PubMed1979

[Scintigraphy in cardiomyopathy].

The function of the right ventricle (RV) and left ventricle (LV) was evaluated in 32 patients with congestive cardiomyopathies (COCM), 10 patients with hypertrophic cardiomyopathy (HOCM) and 21 normal subjects (N). In all these patients myocardial perfusion was analysed using quantitative 201 Tl myocardial perfusion imaging. In COCM parameters of RV and LV performance were significantly reduced (p less than 0.01); regional wall motion analysis revealed a reduced radial shortening ability. Regional Tl-distribution was not different in COCM and N; however, relative Tl-uptake was significantly reduced (p less than 0.05). 80% of all patients with COCM showed the RV free wall on Tl-perfusion scintigrams. These scintigraphic aspects allow a noninvasive differentiation of a disturbed LV function and the classification of coronary and primary myocardial etiology. In patients with COCM the scintigraphically determined thickness of septum and free wall of LV was increased as compared to N (p less than 0.05). The ratio septum/lateral wall of LV averaged 1.3 +/- 0.20. Quantitative analysis of regional Tl-uptake revealed increased segmental relative Tl-uptake. In the majority of patients there was a disproportionate septal hypertrophy on the gated blood pool scan in LAO. These radionuclide techniques allow a dynamic two-dimensional evaluation of the interventricular septum and the LV.

Cardiomegaly↗