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 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In 6 open chest dogs, regional myocardial function und metabolic changes (ATP, creatine phosphate, lactate) were studied during coronary flow reduction in LAD by ultrasonic dimension gauges and transmural biopsies. After reduction of the perfusion pressure from 108 to 50 mm Hg the ischemic segment showed a marked dyskinesis: the enddiastolic segment length increased by 7%, and segment shortening and segment stroke work decreased by 22% and 63% respectively. Left ventricular (LV) enddiastolic pressure rose from 5 to 8 mm Hg (p less than 0.05). Heart rate, LV systolic pressure, LV max dP/dt and Vpm did not change significantly.
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PMID:[Myocardial function and metabolism during local coronary flow reduction]. 91 15

Effect of increased left atrial pressure and a positive inotropic agent upon asynergic left ventricle which was produced by acute occlusion of LAD were examined in 8 open-chest dogs. Systolic bulging in ischemic area was qualified by ESL/EDL in percentage. Left atrial pressure was controlled by the reservoir connected to left atrial appendage with a large bore tubing. Cardiac output and aortic pressure were decreased following coronary occlusion without change in isometric developed tension in nonischemic area of left ventricle. Increase of left atrial pressure from 5 mmHg to 14 mmHg produced rise in stroke volume to 191% and rise in aortic pressure to 156% in asynergic left ventricle respectively. These increases were not accompanied by change in ESL/EDL. Therefore, extracardiac factors were assumed to explain the prominent increase in left ventricular stroke work by elevation of left atrial pressure in asynergic left ventricle. Isoproterenol enhanced total cardiac performance by increasing the function of nonischemic area without deterious effect on the ischemic area.
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PMID:Behavior of asynergic ventricle. 92 17

The 5-HT-2 antagonist ketanserin (KAS) has been successfully used to treat acute hypertension in coronary bypass surgery. The present study was performed to investigate the effect of KAS on ischaemic myocardium. In 11 anaesthetized (piritramide) dogs, systolic contraction (sdL) and end-diastolic length (edL) of myocardium supplied by the left descending coronary artery (LAD) and the left circumflex coronary artery (LCX) were measured by sonomicrometry simultaneously with aortic pressure (AoP), left ventricular dP/dtmax and end-diastolic pressure (LVedP), heart rate (HR), stroke volume, and LAD flow (QLAD). Regional ischaemia to decrease sdLLAD (-48%) was achieved by LAD stenosis (QLAD -47%). Concomitantly, edLLAD increased by 8%. However, the other variables did not change. Then KAS was given i.v. (0.15 + 0.15 + 0.30 + 0.6 mg/kg) at 15-min intervals. Following KAS, prestenotic sdLLAD recovered in a dose-dependent manner. LVedP and edLLAD decreased, sdLLCX increased, and the other variables were not affected. This functional recovery of ischaemic myocardium was attenuated by pretreatment with metoprolol (MET, 1 mg/kg) prior to LAD stenosis. The ischaemic area was not irreversibly damaged, however, as proven by the recovery of prestenotic sdLLAD values after release of the stenosis. The improved systolic shortening of ischaemic myocardium following KAS did not result from restored QLAD due to post-stenotic vasodilation or break up of platelet aggregates (QLAD did not increase) or from reduced afterload (AoP did not decrease). Obviously, it was mediated by beta-1-receptors, as shown by the attenuation of the beneficial effect of KAS by pretreatment with MET.
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PMID:Effects of the serotonin-antagonist ketanserin on the function of ischaemic and normally perfused myocardium and modification by beta-1-blockade in anaesthetized normotensive dogs. 135 17

Comparative studies of the changes in left ventricular (LV) function immediately after aortocoronary bypass graftings (CABG) and early postoperative results were carried out in two groups of patients with severe LV dysfunction (ejection fraction less than 0.4), which consisted of 9 patients received internal mammary artery grafts (IMAG) to at least LAD and 14 with saphenous vein grafts (SVG) only. The utilization of IMAG was limited to the patients with stable preoperative hemodynamics, whereas SVGs were used even in the emergency CABG. Free flow of IMAG measured during operation was 55.7 +/- 25.5 ml/min, which was significantly lower than that (83.5 +/- 27.3) of SVG to LAD. Cardiac index, LV stroke volume index and LV stroke work index immediately after surgery were sufficiently maintained and recovered almost similarly in both groups. Postoperative peak CK-MB (19.7 +/- 10.4 IU/L) in IMAG group was significantly lower than that (23.9 +/- 10.7) in SVG group. There was no significant difference between the two groups in the incidences of postoperative IABP and noradrenaline dependence. There were two hospital deaths in SVG group, whereas no hospital death was experienced in IMAG group. These results indicate that an application of IMAG to LAD in the patients with severe LV dysfunction surely induces satisfactory recovery of hemodynamics immediately after CABG as well as SVG, provided that use of IMAG is limited to the patients with stable preoperative hemodynamics.
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PMID:[Coronary artery bypass grafting in patients with severe left ventricular dysfunction: internal mammary artery vs saphenous vein, evaluation immediately after surgery]. 140 43

To characterize hypertrophy and quantify seasonal changes in cardiac structure and function of women collegiate basketball (BB) athletes (n = 15), echocardiographic (echo) measurements were made in the fall (FALL1), winter (WIN), and spring (SPR), then again during the subsequent fall (FALL2; n = 10). Comparisons were made to age-matched nonathletes (NA) measured during FALL1 (n = 22) and SPR (n = 5). Left ventricular (LV) internal dimension-diastole (LVIDd), LV end-diastolic volume (LVEDV), stroke volume (SV), LV mass (LVM), septal thickness (IVS), LV posterior wall thickness (LVPW), right ventricular (RV) internal dimension-diastole (RVIDd), and aortic root diameter (AOD) were significantly larger (12-70%) in the athletes; RVIDd-, LVEDV-, SV-, and LVM-index were also significantly greater (8-46%). From FALL1 to SPR measurement periods, LVIDd, RVIDd, LVEDV, SV, IVS, and LVM-index increased significantly (7-18%) in the athletes. Over the same period of time, LVIDd, LAD, AOD, LVEDV, and SV measured in the five NA subjects increased significantly. In the athletes, LVIDs, RVIDd, IVS, LVPW, and LVM decreased significantly (5-30%) from the SPR to FALL2 measurement period. These data characterize the general nature of the cardiac hypertrophy noted in women BB athletes compared to NA controls and show that distinct changes in heart structure corresponding to different periods of the competitive season can occur in these athletes.
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PMID:Cardiac structure and function in women basketball athletes: seasonal variation and comparisons with nonathletic controls. 143 64

This study was designed to test the hypothesis that intracoronary administration of esmolol can confer metabolic protection during coronary constriction or occlusion, without affecting hemodynamic parameters, in a canine model. Seventeen anesthetized open-chest dogs underwent direct cannulation of the left anterior descending coronary artery (LADa), its companion vein (LADv), and the distal circumflex vein (CFXv). LADa flow was measured with an electromagnetic flowmeter. Using a micrometer-driven snare around the LADa, flow was reduced by 50%, 75%, and 100% for 15 minutes, with 1 hour of normal flow before each constriction. In 7 dogs (group 1) chosen randomly, esmolol, 15 to 20 micrograms/kg/min, was infused continuously into the LADa; the rate was adjusted to maintain baseline hemodynamic values. The second group (10 dogs) was not treated with esmolol. Heart rate (HR), electrocardiogram (ECG), LADa flow, LV dP/dt, and aorta (Ao), pulmonary artery (PA), LADa, and left ventricular (LV) pressures were recorded continuously. Cardiac output (CO) (thermodilution) was measured and blood was sampled from all catheters before and after constrictions for analysis of glucose, lactate, sodium, potassium, and blood gases. Flow and pressure in the LADa in both groups decreased similarly during each corresponding constriction. Systolic LV pressure, LV dP/dt, and LV stroke work index were affected in both groups only during 100% constriction. HR, Ao, and PA pressures, and total and peripheral pulmonary resistances were affected similarly in both groups during each constriction. Myocardial lactate extraction and consumption were less negative (negative = net production and output) in the LAD perfusion bed during corresponding constrictions with esmolol than without it.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Decreased regional lactate production and output due to intracoronary continuous infusion of esmolol during acute coronary occlusion in dogs. 167 24

The effects of the Hemopump (HP) on left ventricular (LV) and coronary hemodynamics, with and without myocardial ischemia, were studied in an acute, anesthetized, open-chest dog preparation (n = 6). Coronary blood flow velocity in the left circumflex was assessed with an intracoronary Doppler catheter. Measurements were made at two pump speeds (minimal = HP1 and maximal = HP7) before coronary ligation (control), after ligation of the LAD (ischemia), and after induction of cardiac failure by multiple ligations of the diagonal branches (failure). Changing from HP1 to HP7 resulted in 1) Increased total cardiac output in ischemia and failure; 2) Increased mean aortic pressure and systemic vascular resistance in control, ischemia, and failure; 3) Decreased LV external work (LV systolic pressure X stroke volume) in control, ischemia, and failure; 4) Decreased LV end diastolic pressure in ischemia; 5) Decreased LV systolic pressure and pressure-rate product in failure; and 6) Increased coronary blood flow/O2 demand ratio in failure. Hemopump support reduced O2 demand by LV decompression, and improved blood flow/O2 demand ratio in the nonoccluded coronaries of ischemic, failing hearts.
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PMID:Effects of Hemopump support on left ventricular unloading and coronary blood flow. 175 Nov 87

"Critical coronary stenosis" (reduction of coronary blood flow [Q] until reactive hyperaemia following 15s coronary occlusion is just abolished) and "functional stenosis" (reduction of Q until systolic shortening (dL) of post-stenotic myocardium is curtailed by 50%) were compared with respect to the reduction in Q necessary and the effect on regional myocardial and global ventricular function. In 9 anaesthetized (piritramide) dogs, enddiastolic length (edL) and dL of a myocardial area supplied by the left descending coronary artery (LAD) were measured by sonomicrometry. Left-ventricular end-diastolic pressure (LVEDP) and dP/dt, aortic pressure (AoP), stroke volume (SV), and heart rate (HR) were monitored. QLAD was stepwise reduced by a snare. Critical stenosis, present at a 25% reduction of QLAD, had no effect on regional and global ventricular function, but recovery of dL after release of 15s LAD occlusion was significantly delayed. Further obstruction of QLAD progressively impaired dL, reaching 50% dL (functional stenosis) by a flow reduction of about 50%. The decrease in dL was accompanied by an increase in edL. The haemodynamic effects of the functional stenosis were rather discrete (LVEDP + 5%, SV-12%, dP/dtmax-8%). Models of myocardial ischaemia used to study the effect of drugs or other haemodynamically effective interventions should be able to show functional impairment as well as improvement of the ischaemic myocardium. The critical stenosis does not impair myocardial function and, consequently, a favourable influence on the function and, consequently, a favourable influence on the function of ischaemic myocardium by any intervention may not become evident. However, in the presence of a functional stenosis the change in systolic shortening of the ischaemic myocardium is a very sensitive response to any intervention which affects the energy balance of the ischaemic myocardium. Therefore, this model should be preferred.
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PMID:Models of coronary artery disease: "critical" versus "functional" coronary artery stenosis. 201 42

Urapidil (URA) is used to treat acute hypertension in patients with coronary artery disease, but the effect of URA on the performance of ischemic myocardium has not yet been investigated. The present study was intended to assess the function of ischemic myocardium following URA administration. In eight anesthetized (piritramide) open-chest dogs systolic contraction (dL) and end-diastolic length (edL) of myocardium supplied by the left descending (LAD) and circumflex (LCA) coronary arteries were measured by sonomicrometry simultaneously with aortic pressure (AoP), left ventricular end-diastolic pressure (LVedP), heart rate (HR), stroke volume (SV), and LAD-flow (QLAD). QLAD was reduced by LAD stenosis to about 50% of control, decreasing dLLAD by 55%. Concomitantly, edLLAD increased by about 9% and LVedP by 22%, whereas AoP decreased by 5%. Then, URA was given i.v. (0.25 + 0.25 + 0.50 + 1.0 mg/kg) in 15-min intervals. Following URA, the performance of the non-ischemic area was not systematically affected, but dLLAD increased by about 50%. This could neither be related to the significant reduction in afterload (AoP: -8%), nor to an increase in preload (LVedP and edLLAD did not change significantly), nor to an improved oxygen supply via the LAD (QLAD even decreased), although an increased collateral flow the LCA could not be excluded. The increase in systolic shortening correlated very closely to a decrease in heart rate (r = -0.92). It is concluded that the improved function of ischemic myocardium following urapidil resulted from a reduced oxygen demand in consequence to the decrease in heart rate.
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PMID:Effect of urapidil on the performance of ischemic myocardium in anesthetized dogs. 238 20

This study was designed to test the hypothesis that beta-adrenergic receptor blockade with esmolol would decrease the hemodynamic and myocardial metabolic impairment produced by left anterior descending coronary artery (LADa) occlusion. Twenty-three anesthetized open-chest dogs underwent direct cannulation of the LADa, its companion vein (LADv), and a distal circumflex vein (CFXv) for blood sampling. All dogs were subjected to two consecutive 15-minute periods of total LADa occlusion; group 1 (n = 11) received an infusion of esmolol (150 micrograms.kg-1.min-1) during either occlusion period (randomly assigned) and group 2 (n = 12) received no intervention during either occlusion period. One hour of reperfusion was interposed between the two periods of LADa occlusion. Hemodynamic measurements were made and blood was sampled from the aorta, CFXv, LADa, and LADv before and during both periods of LADa occlusion. Without esmolol infusion, LADa occlusion was associated with decreases in stroke index, coronary perfusion pressure, and left ventricular stroke work index; with esmolol infusion these hemodynamic decrements did not occur. During both LADa occlusion periods in both groups, lactate extraction became negative, i.e., there was net lactate production. Despite this, the magnitude of lactate production was less with esmolol than without it. Finally, average endocardial-to-epicardial blood flow ratio in the LAD perfusion area was decreased during each LAD occlusion period except when esmolol was infused, during which the baseline value was maintained. Thus, infusion of esmolol during temporary LADa occlusion preserved certain hemodynamic variables, preserved the ratio of endocardial-to-epicardial blood flow, and decreased the apparent magnitude of lactate production.
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PMID:Esmolol decreases the adverse effects of acute coronary artery occlusion on myocardial metabolism and regional myocardial blood flow in dogs. 282 57


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