Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Myocardial Contraction”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1979

[Effect of strophanthin and cytochrome C on myocardial contraction and the incidence of shock and ventricular fibrillation in experimental myocardial infarct].

High ligation of the interventricular artery caused ventricular fibrillation in the first 2--4 minutes in 20% of cats. In the remaining animals myocardial contractility diminished to half its initial value. After that, contractility increased gradually. In cardiosclerosis myocardial contractility reduced by 20--30%. Ligation of the interventricular artery on the background of cardiosclerosis induced cardiogenic shock in half of the animals. Cytochrome C does not reduce the diminution of myocardial contractility after ligation and has a marked antifibrillatory effect. Strophantin does not affect the diminution of contractility of a healthy myocardium but reduces the decrease in contractility of a sclerosed myocardium and also promotes the development of ventricular fibrillation following ligation of the interventricular artery.

Animals↗
PubMed1979

[Correlation of the parameters of myocardial contraction and relaxation in compensatory cardiac hypertrophy].

The parameters of myocardial contraction and relaxation were determined from the left ventricular pressure curves obtained in closed chest rabbits. One month after the creation of ascending aorta stenosis when the relative weight of the left ventricle increased by 54% as compared to the control, systolic pressure was higher by 42% and maximum rate of pressure development by 47%. This increase corresponded to the degree of left ventricular hypertrophy so that the load on the unit of myocardial mass did not change. No changes were found in the contractility index. The index of relaxation, however, determined by the relation between the maximum rate of relaxation and the developed pressure and characterizing the function of the myocardial relaxation system was 20% lower than that of the control. This was associated with the decrease of the diastolic pause by 27%. The slowing down of relaxation is one of the first and must' signs of compensatory function of the heart.

Animals↗
PubMed1977

Correlation of myocardial contraction band necrosis and vascular patency. A study of coronary artery bypass graft anastomoses at branch points.

Eleven patients who died within 1 week of operation and in whom saphenous vein bypass graft anastomoses were located at or extended across coronary artery branch points were studied at autopsy. New surgically introduced narrowings of greater than 75% in one branch of the 13 anastomoses studied were more frequent (six of eight) when the arteriotomy extended into a branch artery than when the arteriotomy ended proximal to the flow divider of the branch point (zero to five). Obstruction was most frequently caused by suture compression of the arterial lumen. In five of the six anastomoses, where one branch contained a significant new narrowing and the other did not, a striking difference in the severity of myocardial contraction band necrosis in the distribution of the two arteries was found. In each such case the severe necrosis was in the distribution of the patent branch artery and the obstructed branch had slight or trivial injury. The results are interpreted as showing that myocardium that has the potential for developing contraction band necrosis may not develop it if the reflow phase is suppressed.

Adult↗
PubMedDate not supplied

[Relationship between the amplitude of myocardial contractions in frogs and the frequency of electrical stimulation. Role of external and intracellular calcium in the coupling of excitation and contraction].

Ionic currents were studied on the frog atrial trabeculae (Rana ridibunda) at 20 degrees C using a double sucrose gap voltage clamp arrangement. The net inward current peaks did not change in the course of repetitive stimulation (0,5/s) in contrast to the increase of the contraction amplitude (isometric tension) in the similar conditions (Bowdich staircase). The slow component of the net inward current revealed under the action of TTX (2-10(-8) g/ml) was increased upon the increase of external Ca concentration but was blocked when D-600 was introduced into the solution. The inhibitory action of D-600 on the contraction amplitude was frequency independent (in the ranges: 0,1--0,7/s). The decrease of external Na+ (isoosmotic replacement of 70% NaCl by sucrose) or the increase (5-fold) of the external Ca2+ significantly enhanced the myocardial contraction depressed with D-600. However these contractions fall in the course of rhythmical stimulation, and the effect being strongly dependent on the rate of stimulation. The results confirm the assumption (see: Biophysics, 6, 1024, 1976), that intracellular Ca stores (sarcoplasmic reticulum, internal surface of the cellular membrane) are involved in the control of the contractility in the amphibian myocardial cells. Many peculiarities of the excitation-contraction coupling in the frog myocardial cells can be explaned if one assumes that: 1) there is no space separation of primary uptake and release of Ca ion sites in the frog myocardium; 2) the system of "resting Ca chanels" in the frog myocardial cells is not so well developed as in the mammalian myocardial cells.

Animals↗
PubMed1975

The effect of pancuronium on myocardial contraction and catecholamine metabolism.

The effects of pancuronium bromide infusion on the uptake and release of [14C] noradrenaline (14C-NA) by the isolated, perfused rat heart and on the chronotropic and inotropic activity of the isolated heart were evaluated. Hearts were removed from animals under light ether anaesthesia, transferred to a modified Langendorff perfusing apparatus and perfused with Krebs-Ringer bicarbonate solution at a rate of 5 ml min-1. The effect of pancuronium on the uptake of noradrenaline was determined by perfusing hearts for 5 min with perfusate containing various concentrations of pancuronium and 200 ng ml-1 of 14C-NA. After 5 min pancuronium-treated hearts contained less 14C-NA. The degree of reduced uptake increased with increasing concentrations of pancuronium. In addition, the combination of pancuronium perfusion and electrical stimulation (15 mA for 10 ms at 4 Hz) blocked the 50 min uptake of 14C-NA by the heart to a greater degree than either factor separately. The release of noradrenaline was determined after perfusing hearts with 14C-NA followed by perfusion with solution containing pancuronium but no 14C-NA for 1 h. Pancuronium infusion did not significantly alter the release of 14C-NA from the heart after 1 h of perfusion. The infusion of pancuronium caused a reduction in both the rate and strength of myocardial contraction of the isolated heart which was reversed by perfusion with perfusate free of pancuronium. Following perfusion with pancurnium the rate and strength of contraction of the heart was seen to "rebound" above pre-pancuronium values for a short period. The rebound of myocardial rate and contraction may have been due to the presence of myocardial noradrenaline previously blocked from reuptake by pancuronium since hearts removed from reserpinized animals did not demonstrate "rebound."

Animals↗
PubMed1978

Correlation of systolic time interval with abnormal myocardial contraction by coronary occlusion in anesthetized open-chest dogs.

The correlation between the systolic time interval and abnormal contraction in ischemic myocardium was studied in anesthetized open-chest dogs. A strain-gauge was sutured on the surface of the left ventricular wall perfused by the left anterior descending coronary artery (LAD) for measuring segment-length. The left ventricular stroke volume decreased progressively after occlusion of LAD. The left ventricular ejection time (LVET) was progressively shortened in close correlation with the elongation of segment-length at the onset of isometric relaxation in 20 seconds after LAD occlusion when early systolic myocardial contraction and isometric contraction time (ICT) were not affected. ICT was gradually prolonged and closely related with the lengthening of the early systolic segment-length, while LVET recovered toward the control level in spite of further decrease in stroke volume. A close relationship was observed between ICT/LVET and stroke volume (gamma = 0.76, P less than 0.01). The results suggested the possibility that LVET was normalized even when the left ventricular function was impaired, and ICT/LVET ratio was the most sensitive index of LV dysfunction.

Animals↗
PubMed1979

[Various characteristics of lipid metabolism in experimental myocardial infarct and their effect on myocardial contraction].

It was established in rabbit experiments that in acute focal myocardial ischemia induced by ligation of the descending branch of the left coronary artery, diminution of the force of cardiac contractions and an increase in the content of free fatty acids in blood plasma are observed. Progressing intramyocardial lipolysis is noted for 6 days. Lipolysis blockade with large doses of nicotinic acid leads to an extremely sharp drop in the contractile force of the heart in experimental animals with acute focal myocardial ischemia and to drastic damage of the myocardial ultrastructures as well as to disorders of the metabolism of intracellular lipids.

Acute Disease↗
PubMed1976

Correlation of electrocardiogram and vectorcardiogram with coronary occlusion and myocardial contraction abnormality.

Electrocardiograms and Frank vectorcardiograms were recorded in 156 consecutive patients with total occlusion of at least one coronary artery (on arteriography) and associated left ventricular contraction abnormality (on ventriculography). The angiograms and cardiograms were independently reviewed. In the presence of single vessel occlusion, appropriate vectorcardiographic diagnosis of myocardial infarction was determined in 118 of 156 cases (76 percent) compared with a lower electrocardiographic detection rate in 77 of 156 cases (49 percent). Findings diagnostic of two coexisting infarctions were observed in 71 percent of vectorcardiograms and 37 percent of electrocardiograms in 51 patients with double vessel occlusion and two areas of left ventricular dyskinesia. The vectorcardiographic detection rate was similarly superior to the electrocardiographic rate in the presence of subtotal coronary occlusion and myocardial asynergy in single (73 percent versus 53 percent) and double (53 percent versus 28 percent) vessel disease. The incidence rate of false positive diagnoses was 3 percent for electrocardiography and 4 percent for vectorcardiography. It is concluded that the vectorcardiogram is superior to the electrocardiogram in the diagnosis of obstructive coronary artery disease and left ventricular contraction abnormality.

Adult↗