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Biomedical subjects

E Barta

Publications and source records attributed to E Barta.

96 records · Page 6Linked to original sources
PubMedDate not supplied

Characterization of regional left ventricular contraction by curvature difference analysis.

A method which characterizes the contraction of the left ventricle (LV) by changes in the LV endocardial contour curvatures is presented. A normalized curvature difference function (NCDF) is defined by the difference between the (normalized) curvature functions of end diastolic (ED) and end systolic (ES) contours. Unlike wall-motion based procedures, NCDF is independent of any reference system and of the method used for ED-ES shape alignment. Normal and pathological diagnosis criteria were first established based on right anterior oblique (RAO) projection ventriculograms of a study group which included 58 normal and 28 abnormal patients. Patients with an infarcted myocardial region differed from the characteristic NCDF pattern of normals and exhibited regionally defined irregularities. The diagnosis criteria were then applied to a total of 159 patients in two groups in two independent laboratories. One group (in Israel) included 49 cases (20 normals, 29 abnormals); the second (in France) included 108 cases (48 normals, 60 abnormals). These two groups yielded similar sensitivity (97% and 97%) and specificity (90% and 100%) in detection of abnormality of the ventricle. When tested against other quantitative wall motion techniques, the NCDF shwos a regional sensitivity of 95%, indicating that curvature difference analysis is a potential tool for the automatic and objective diagnosis of regional LV function abnormalities.

Heart↗
PubMedDate not supplied

Geometry of the conduit coronary artery in diastole is determined by the volume of the left and right ventricles.

In the canine heart placed in a bath the ramus interventricularis anterior (RIA) was perfused under constant pressure. Segment length and diameter of RIA were monitored by ultrasound technique, coronary pressure by electromanometer. Increasing the volume of the left ventricle by up to 150% of the physiological value increased the segment length by 3.73-12.72% and decreased the diameter by 3.14-9.37%. Similar increments of right ventricular volume increased coronary segment length by 4.38-13.02% and decreased diameter by 2.85-16.45%. In concert with the dynamics of heart deformation segment length and diameter changes were larger in the proximal (close to the basis of the heart) than in the distal part of the artery (close to the apex). Implications of this phenomenon in physiological and/or pathophysiological regulation processes are presented. The results have a methodological implication for in situ studies of coronary smooth muscle activity. When the diameter of the coronary artery is taken as an indicator of smooth muscle activity the ventricular volumes should be kept constant.

Animals↗
PubMedDate not supplied

Activity of sympathetic nerves in heart during cardiopulmonary bypass in patients.

The sympathetic nerve activity in heart during cardiopulmonary bypass was studied in 20 patients. The rate of release of dopamine-beta-hydroxylase from cardiac nerves was used as an indicator. It was found that the thoracotomy alone does not represent such a stimulus which would lead unambiguously to sympathetic overactivity in heart. Cardiopulmonary bypass represents, on the other hand, an intensive sympathomimetic stimulus, as it was demonstrated by significnat increase of coronary A-V difference negativity of dopamine-beta-hydroxylase as early in 15th minute of its duration. The washout of enzyme to the end of 30 min. duration of bypass still increased. After finishing of bypass the coronary A-V diff. of dopamine-beta-hydroxylase again decreased.

Cardiopulmonary Bypass↗
PubMedDate not supplied

Protective effect of alpha-tocopherol and L-ascorbic acid against the ischemic-reperfusion injury in patients during open-heart surgery.

The purpose of the investigation was: 1. to examine the effect of cardiopulmonary bypass (CPB) on the generation of cytotoxic oxygen-derived radicals and 2. to determine if the pretreatment of patients with vitamins E and C will combat generation of such radicals. Twenty patients undergoing CPB for treatment of cardiac disease were entered into the study and randomized to one of two groups. Group 1 (n = 9) served as control. Group 2 (n = 11) consisted of patients pretreated with 2000 IU of vitamin E 12 h prior to surgical intervention and 2 g of vitamin C given in the morning on the day of operation. Blood samples from arterial and mixed venous blood for analysis were obtained at the following intervals: 1. before anesthesia, 2. before sternotomy, 3. at the start of CPB, 4. at the end of CPB, 5. at the time of skin closure, 6. in the morning of the following day. Blood specimens from the coronary sinus were withdrawn A--before aortic cross-clamping, B--immediately after aortic declamping, C--in the 5th min, and D--in the 15th min of reperfusion. The concentration of inorganic phosphate as well as of uric acid was significantly higher in the control group what might indicate that vitamins E and C attenuate the degradation of adenine nucleotides. The most important difference between treated and control groups was observed in plasma concentration of malondialdehyde--a marker of lipid peroxidation--which was significantly lower in pretreated patients. A similar pattern of changes was found in the level of the lysosomal enzyme N-acetyl-glucosaminidase. Finally, pretreatment with vitamins E and C inhibited the decrease of catalase, observed in controls.

Animals↗