Search PubMed⌕ Search

Biomedical subjects

J Lekven

Publications and source records attributed to J Lekven.

87 records · Page 5Linked to original sources
PubMed1975

Effect of practolol on left ventricular dimensions during coronary occlusion.

Beta adrenergic blockade has been suggested to improve the myocardial oxygen balance during ischemic conditions. This investigation was undertaken to examine the effects of practolol, a relatively cardiospecific beta adrenergic blocking agent, on regional myocardial dimensions and shortening during acute coronary arterial occlusion in dogs. Local myocardial dimensions were measured ultrasonically in ischemic and nonischemic regions of the left ventricle. Myocardial dilatation and marked reduction in systolic shortening occurred in ischemic regions after occlusion, whereas nonischemic regions were only moderately dilated. Administration of 10 to 20 mg of practolol exerted different effects in the two ventricular regions; myocardial dilatation was reduced and the systolic shortening increased by practolol in ischemic regions, whereas further dilatation and diminished shortening occurred in nonischemic control regions. Similar results were obtained when heart rate was kept constant by atrial pacing during beta adrenergic blockade. Thus, practolol improved the function in ischemic ventricular regions, and restored ventricular stroke volume to preocclusion levels, probably as a result of improved myocardial oxygen balance.

Animals↗
PubMed1975

Myocardial function in general and regional left ventricular ischaemia in dogs at control and high aortic blood pressure.

End-diastolic dilation and reduced systolic shortening are the characteristic dimensional changes during myocardial ischaemia. Elevation of systolic aortic blood pressure by 5.3 kPa (40 mm Hg) normalized shortening and reduced myocardial dilatation when the tissue rendered ischaemic by coronary artery occlusion was less than 20% of the left ventricle. However, when the ischaemic lesion was more extensive, an adverse effect of raising aortic blood pressure was observed.

Animals↗
PubMed1975

Relationship between ST-segment elevation and local tissue flow during myocardial ischaemia in dogs.

The relationship between electrocardiographic ST-segment changes and local tissue flow recorded from idential sites in the myocardium was determined by inserting platinum electrodes into the left ventricular wall of anaesthetized dogs. Local myocardial blood flow was measured during graded coronary constriction by recording tissue hydrogen desaturation rate. In the detection of ischaemic ST-segment elevation, intramural recordings proved to be more sensitive than corresponding epicardial recordings. Significant ST-segment elevation could only be detected by reducing local myocardial flow below 50% of control; by further reduction ST-segment elevation increased in proportion to the reduction in myocardial flow. Thus, significant myocardial ischaemia might exist without electrocardiographic alterations.

Animals↗
PubMed1974

Importance of free fatty acids as a determinant of myocardial oxygen consumption and myocardial ischemic injury during norepinephrine infusion in dogs.

Increased delivery of free fatty acids raises myocardial oxygen consumption (MVO(2)) without influencing mechanical performance. The effects of norepinephrine on MVO(2) and on the size of ischemic injury after acute coronary occlusion were therefore studied before and during inhibition of lipolysis with beta-pyridylcarbinol. In spite of similar mechanical responses to norepinephrine, MVO(2) increased by 57+/-11% before and significantly less, 31+/-6%, (P < 0.01) during inhibition of lipolysis. After coronary occlusion the ischemic injury associated with norepinephrine infusion, as evidenced by epicardial mapping of S-T segment elevation, was larger before (7.9+/-1.1 mV) than during inhibited lipolysis (2.8+/-0.4 mV; P < 0.005). Average S-T segment elevation associated with norepinephrine infusion during inhibited lipolysis (2.8+/-0.4 mV) was even lower (P < 0.05) than during control occlusion alone, before drug administration (4.4+/-0.7 mV). In conjunction with an antilipolytic agent, norepinephrine was shown to reduce the extent and magnitude of the myocardial ischemic injury produced by acute coronary occlusion; this could be due to an improved balance between myocardial oxygen supply and requirement.

Animals↗
PubMedDate not supplied

Temporary ischaemia of a large bowel segment induced by degradable starch microspheres in man.

Degradable starch microspheres were used to induce temporary ischaemia measured by electromagnetic flowmetry in colon segments during bowel resection. Severe reversible ischaemia free from unwanted side effects was induced in eight of nine patients. In one of the five patients where the tumour was included in the microsphere-embolised tissue volume no reduction in blood flow was seen. Segmental enteric ischaemia induced by degradable starch microspheres in man seems safe and may be useful for radioprotective purposes in clinical radiation therapy.

Aged↗