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At least 307 records · Page 17Linked to original sources
PubMed1989

Measurement of hepatocellular function, cardiac output, effective blood volume, and oxygen saturation in rats.

The available techniques do not permit the measurement of hepatocellular function, cardiac output, effective blood volume, and oxygen saturation in small animals without the need of blood or tissue sampling. We present methodology that permits us to measure the above variables in the rat. Multiple doses of indocyanine green (ICG; 0.16-2.6 mg/kg) were given to pentobarbital-anesthetized rats, and [ICG] was continuously measured by an in vivo hemoreflectometer. Initial velocity of clearance (Vo) was determined from the [ICG] vs. time plot for each dose by nonlinear regression. The maximal velocity of clearance (Vmax; indicating hepatocellular function) was calculated. Vmax was 1) accurately determined using two, three, or four doses of ICG; 2) it was 1.09 +/- 0.16 mg.kg-1.min-1, not different from the Vo of the near-saturating dose of 25 mg/kg; and 3) it decreased after partial hepatectomy. Cardiac output was 41.89 +/- 1.46 ml.100 g-1.min-1, effective blood volume was 6.12 +/- 0.34 ml/100 g, and oxygen saturation was 92 +/- 2%. These methodologies may prove useful in the evaluation of hepatocellular dysfunction and hemodynamic parameters in the rat during and after various diseased states.

Animals↗
PubMed1991

[Modern techniques of assistance and mechanical replacement of cardiac function].

There has been intensive technological and clinical research for many years into the assistance and mechanical replacement of cardiac function. The simplest systems (extracorporeal circulation using centrifuge pumps, hemopump) and more complex systems (orthotopic or heterotopic pneumatic ventricles, electric ventricles) have been shown to be effective in a variety of situations which up to now could not be controlled by pharmacological methods. These situations are made amenable to improvement by the application of these techniques. They make it possible to await the recovery of autonomous function or, in its absence, transplantation. Experience over the past 30 years provides guidance for current research into the artificial heart.

Heart Diseases↗
PubMed1992

Influence of pregnancy on mean systemic filling pressure and the cardiac function curve in guinea pigs.

To assess the degree of circulatory fullness and to evaluate the influence of peripheral and cardiac factors in the regulation of cardiac output during pregnancy, the following studies were conducted using pentobarbital-anesthetized, open-chest nonpregnant and late term pregnant guinea pigs. Mean circulatory filling pressure was taken as the equilibrium pressure when the pulmonary artery was constricted. Total vascular compliance was assessed by +/- 5-mL changes in blood volume performed while this constriction was maintained. A separate group of guinea pigs was prepared with a pulmonary artery electromagnetic flow probe and right atrial catheter. Rapid infusion of saline was used to increase right atrial pressure while the cardiac output was determined. Pregnancy was characterized by the following changes relative to nonpregnant controls: 51Cr-labelled RBC blood volume increased from 55 +/- 3 to 67 +/- 3 mL/kg; mean circulatory filling pressure increased from 7.1 +/- 0.2 to 8.0 +/- 0.5 mmHg (1 mmHg = 133.322 Pa); right atrial pressure decreased from 3.4 +/- 0.2 to 2.1 +/- 0.3 mmHg; and cardiac output increased from 71.8 +/- 3.9 to 96.8 +/- 3.3 mL.min-1.kg-1. Total vascular compliance was not changed (2.1 +/- 0.1 mL.kg-1.mmHg-1) and most of the expanded blood volume was accommodated as unstressed volume. The cardiac function curve was shifted upwards in pregnant animals. The resistance to venous return, as determined from the slope of the venous return curves, was not changed. These data suggest that the circulation of the pregnant guinea pig is slightly overfilled.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[Effects of NaHCO3 on cardiac function and metabolism during hypoxic metabolic acidosis--2: Rapid infusion of NaHCO3].

The effects of 1M sodium bicarbonate (NaHCO3) on cardiac function and myocardial metabolism during hypoxia were compared with those of 1M sodium chloride (NaCl) in anesthetized dogs. Metabolic acidosis was induced with inhalation of low fraction of oxygen (9%) for 2 hours. NaHCO3 (n = 9) or NaCl (n = 10) was infused intravenously in a half dose of 0.2 x body weight x base excess mEq in 30 seconds. This treatment was repeated five minutes later. In NaHCO3 group; with first infusion, both blood and intramyocardial pH increased. Left ventricular pressure (LVP) and maximum rate of rise of LVP (LV dP/dt max) were unchanged. Cardiac index (CI) tended to increase, while left ventricular end-diastolic pressure (LVEDP) and LVEDP/LVP increased significantly. In five dogs in which myocardial glucose uptake increased, LV dP/dt max increased. With the second infusion, inspite of the increase of blood and intramyocardial pH, LVP and LV dP/dt max decreased significantly compared with the preceding values. In NaCl group, with first infusion, blood and intramyocardial pH decreased. CI increased significantly, while LVP and LV dP/dt max tended to decrease, and LVEDP and LVEDP/LVP increased significantly. After the second infusion, myocardial contractility was depressed significantly. In both groups, blood lactate (LA) level increased significantly, especially with NaHCO3 infusion. LV dP/dt max correlated significantly with LA in NaCl group (r = -0.614, P < 0.001). However, in NaHCO3 group, LV dP/dt max did not correlate with LA. Blood glucose level (r = 0.612, P < 0.001) and myocardial glucose uptake (r = 0.718, P < 0.001) correlated significantly with LV dP/dt max in NaHCO3 group.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis, Respiratory↗
PubMed1972

Changes during eating in oxygen consumption, cardiac function and body fluids of sheep.

1. A study was made of the changes taking place in O(2) consumption, cardiac function and the volume and composition of the body fluids of sheep while they consumed a meal of hay.2. During eating P(a, CO2) and P(v, CO2) both increased, pH decreased and free plasma [HCO(3) (-)] increased. Venous haematocrit increased sharply at the beginning of the meal, and declined slowly after feed was removed.3. Arterial P(O2) did not change significantly during eating. However P(v, O2) fell slightly but significantly. The O(2) saturation of venous blood fell due to the decline in pH. Estimated CO(2) in arterial blood increased as a consequence of increased haemoglobin content. The net effect was to increase arteriovenous difference in O(2) content from 4.4 ml./100 ml. before eating to 6.0 ml./100 ml. at the end of the meal.4. O(2) consumption increased about 60% during eating and fell rapidly thereafter. Heart rate followed a similar pattern. Cardiac output however increased only about 17%, from 6 to 7 l./min. Consequently stroke volume declined throughout the meal from 76 to 52 ml./beat.5. Plasma volume, estimated from measurements of T-1824, declined sharply by about 300 ml. at the beginning of the meal and recovered slowly after feed was removed. Blood volume declined less because of a rise in circulating erythrocytes.6. Extracellular fluid volume was estimated from measurements of thiocyanate and thiosulphate spaces. Thiocyanate space measurements were abandoned after thiocyanate was found to be concentrated in saliva. Considerable random variation occurred in measurements of changes in extracellular fluid from thiosulphate disappearance but the results did reveal a significant fall of 1000-1500 ml. in extracellular fluid volume during eating.7. The significance of these interrelated changes is discussed in relation to the maintenance of homoeostasis during eating in the sheep.

Animal Nutritional Physiological Phenomena↗
PubMed1995

[Cardiac function in isolated working rat heart with pressure overload hypertrophy: correlation with myocardial angiotensin II].

Using the isolated working rat heart model, we recorded cardiac function of the hypertrophied hearts induced by abdominal aortic banding and determined the myocardial angiotensin II level. Compared with the sham-operated control hearts, the maximal diastolic rate (-dp/dt) and coronary flow rate (per gram of left ventricular weight) were decreased, while the myocardial angiotensin II content was increased in the hypertrophied hearts. Correlation analysis revealed that both coronary flow rate (r = -0.8097, P < 0.001) and -dp/dt (r = -0.5463, P < 0.01) were negatively correlated to myocardial angiotensin II. We conclude that the activated cardiac renin-angiotensin system may be responsible for the decreased diastolic function and coronary reserve in the hypertrophied hearts.

Angiotensin II↗
PubMed1983

Cardiac function in adolescents and young adults with anorexia nervosa.

Twelve patients with anorexia nervosa (mean age 17.6 years) underwent noninvasive cardiac evaluation. All patients had normal sinus rhythm at rest, during exercise, and following 24-hr electrocardiographic monitoring. The chest roentgenograms demonstrated a small heart secondary to a loss of left ventricular mass. Three of four patients studied had left ventricular mass measurements less than 100 g (normal is 90-360 g). Most patients had an elevated heart rate response to exercise with a slightly blunted systolic and a normal diastolic blood pressure response. Eleven of the 12 patients had reduced overall maximal working capacity. All but one had normal left ventricular ejection fraction at rest. There was no evidence of arrhythmias at rest, during exercise, or with continuous electrocardiographic recording. Young patients with anorexia nervosa appeared to have essentially normal cardiac function with a reduction in left ventricular muscle mass.

Adolescent↗
PubMed1988

Cardiac function in open-chest dogs after left to right ventricular shunting and right coronary artery occlusion.

Patients with acquired ventricular septal defect (VSD) after myocardial infarction have a particularly bad prognosis if right ventricular function is severely impaired. The significance of an ischaemic right ventricular free wall on cardiac function during interventricular shunting was examined in open-chest dogs. An external interventricular shunt could be opened and closed at will, and by occlusion of the right coronary artery (RCA), a part of the right ventricular free wall was rendered ischaemic. Aortic flow decreased by 8 +/- 2% when the shunt was opened in the presence of a normal right ventricle, and by 16 +/- 2% (difference: P less than 0.05) in the presence of right ventricular ischaemia. Aortic flow fell by 19 +/- 3% when the RCA was occluded. Right ventricular dyskinesia was demonstrated after occlusion of RCA, by recording segment lengths in the right ventricular free wall. The dyskinesia was aggravated when the shunt was opened. The left ventricle exerted a 'negative' work on the ischaemic right ventricular free wall. Retention of blood in the right ventricle, with a subsequent decline in left ventricular filling and an almost unchanged interventricular shunting of blood, explain why aortic flow fell more when the shunt was opened in the presence of right ventricular ischaemia.

Animals↗
PubMed1993

Effects of thiopental and ketamine on cardiac function during moderate hemorrhage in chronically instrumented rats.

This study was designed to assess the effects of thiopental and ketamine on cardiac function after a blood loss of 2 ml/100 g of body weight. In nine Sprague-Dawley rats, a catheter was placed in the abdominal aorta, a pulsed Doppler probe was positioned around the thoracic aorta, and a wall-thickness probe was sutured onto the left ventricle. On three occasions, all rats were studied awake, during thiopental anesthesia, and during ketamine anesthesia. In awake rats, a 30% blood loss resulted in an immediate, transient hypotension (49%) and a prolonged decrease in cardiac output (39%) and stroke volume (28%). No significant changes were observed in the wall-thickening fraction, which is an index of cardiac contractility, and in the heart rate. The effect of thiopental on cardiovascular responses to moderate hemorrhage was minimal. Although ketamine did not affect the hypotensive response to moderate hemorrhage, it did accentuate systemic vasoconstriction and cardiac depression as indicated by a decrease in cardiac output (57%), stroke volume (49%), and wall thickness (47%).

Animals↗
PubMed1995

Differential effects of OPC-18790, amrinone and dobutamine on cardiac function and energy metabolism in the guinea-pig isolated ischaemic heart.

1. The effects of OPC-18790, a novel positive inotropic agent, on cardiac function and myocardial energy metabolism in the guinea-pig isolated heart with ischaemia were studied by 31P-magnetic resonance spectroscopy (MRS) and compared with those of amrinone and dobutamine. 2. Cardiac ischaemia was induced by intracoronary infusion of 15 microns microspheres to reduce coronary perfusion flow (CPF) by 50%. Microsphere embolisation caused a 40% decrease in left ventricular systolic pressure (LVSP), cardiac contractility measured by peak of ventricular pressure development (LVdP/dt) and slightly reduced heart rate. There was also a decrease in ATP and creatine phosphate (PCr) by 20%, an increase in inorganic phosphate (Pi) by 25% and an acidic shift of intracellular pH in the ischaemic heart. 3. In the ischaemic heart, OPC-18790, amrinone and dobutamine were applied at concentrations which increased LVdP/dt by about 60%. These compounds increased LVP by 15% to 30% and increased CPF by about 10%. Amrinone and dobutamine but not OPC-18790 increased heart rate. When these drugs produced the haemodynamic changes described above, amrinone and dobutamine reduced ATP and PCr, increased Pi and produced further intracellular acidosis, whereas, OPC-18790 did not change these parameters. 4. Cardiac pacing at 285 beats min-1 produced decreases in LVP, LVdP/dt and CPF by about 30%, 20%, 5%, respectively and an increase in Pi, decreases in PCr and ATP, and intracellular acidosis. 5. These results suggest that degradation of high energy phosphate compounds closely relates to increase in heart rate in the ischaemic heart. Positive inotropic agents without chronotropic action seem to be beneficial in support of the ischaemic heart.

Adenosine Triphosphate↗
PubMed1991

Hypertonic saline dextran resuscitation fails to improve cardiac function in neonatal and senescent burned guinea pigs.

Our previous studies suggested that the greater diminution in burn-induced cardiac contractile function which occurs in young and elderly subjects compared with adult subjects is related to differences in intracellular calcium availability to the myofilaments. We recently showed that improved cardiac function after hypertonic saline dextran (HSD) resuscitation from burn injury in adults was related to enhanced intracellular calcium content. In the study presented here, 126 hearts isolated from neonatal, adult, and senescent guinea pigs were used to evaluate age-related differences in cardiac contractile response to HSD resuscitation from burn injury. Scald burn was induced in 30 adult, 18 neonatal, and 30 senescent guinea pigs; within each age group, half of the burned animals were resuscitated with lactated Ringer's (Parkland formula, 4 mL/kg/% burn for 24 hours); half received an initial bolus of HSD (4 mL/kg, IV) plus lactated Ringer's (1 mL/kg/% burn for 24 hours). An additional 16 animals from each age group served as sham burn controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1991

Pharmacologic interventions for the neonate with compromised cardiac function.

The developmental aspects of myocardial performance must be considered when pharmacologic agents are used to support the neonate with compromised cardiac function. Neonatal cardiovascular function is characterized by a limited preload reserve, decreased ventricular compliance, limited contractile reserve, and CO that is primarily dependent on the HR. Nurses caring for these neonates need a baseline understanding of normal cardiovascular physiology to evaluate the effectiveness of pharmacologic interventions to augment CO. Neonatal nurses play a pivotal role in the therapeutic management of pharmacologic interventions to provide safe, high quality care for the sick neonate.

Cardiovascular Agents↗
PubMed1986

The effects of burn injury and fluid resuscitation on cardiac function in vitro.

The effects of a 30% full-thickness total body surface area scald burn on in vitro mechanical cardiac function was studied in Sprague-Dawley rats. The findings were a 50% decrease in tension development and velocities of contraction and relaxation, when papillary muscle functions from sham and unresuscitated burned animals were compared. Fluid resuscitation synchronous with burning completely reversed the defects in papillary muscle function. This defect in function was partially transferable to normal muscles incubated in serum from burned rats.

Animals↗
PubMed1984

Disturbed cardiac function possibly associated with mianserin therapy.

Two patients, who were receiving therapy with mianserin for depressive disorders, developed signs of disturbed cardiac function which resolved after mianserin therapy was discontinued. One of the patients also developed hypokalaemia which was probably caused by the drug. It is felt that these side effects warrant further research.

Aged↗
PubMed1987

Pulsed Doppler and two-dimensional echocardiography: comparison of halothane and isoflurane on cardiac function in infants and small children.

The combination of two-dimensional and pulsed Doppler echocardiography was used to measure determinants of cardiac function in 20 ASA physical status I infants and small children (9 days-32 months of age) during equipotent halothane (n = 10) or isoflurane (n = 10) anesthesia in oxygen. Five sets of cardiovascular data were recorded in each patient. In the awake, unmedicated state prior to induction, at three different anesthetic levels, 0.75, 1.0, and 1.25 MAC (corrected for age) and a final measurement repeated at 1.25 MAC after the intravenous infusion of 15 ml X kg-1 of Lactated Ringers solution. The study was completed prior to intubation and surgery. Results are expressed as mean +/- SEM. Isoflurane and halothane decreased mean blood pressure from the awake level (isoflurane 76.6 +/- 2.3 to 60.6 +/- 3.1 mm, halothane 72.2 +/- 3.9 to 60.6 +/- 3.1 mm at 1.25 MAC). Isoflurane increased heart rate at all anesthetic levels (128.7 +/- 4.2 to 142.5 +/- 6.0 beats/min at 0.75 MAC). Halothane decreased heart rate at 1.25 MAC (124.6 +/- 4.6 to 119.4 +/- 3.5 beats/min). Isoflurane and halothane decreased cardiac index at 1.25 MAC. Stroke volume index decreased at 1.0 and 1.25 MAC with both isoflurane (36.9 +/- 3.8 to 30.2 +/- 3.5 ml/m2) and halothane (32.7 +/- 2.5 to 28.9 +/- 2.5 ml/m2). Ejection fractions also decreased significantly at 1.0 and 1.25 MAC in both groups of patients (22 +/- 6% at 1.25 MAC halothane and 28 +/- 8% at 1.25 MAC isoflurane).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1984

Evaluation of size and dynamics of the inferior vena cava as an index of right-sided cardiac function.

To define normal criteria of size and dynamics of the inferior vena cava (IVC) and its clinical value in assessing right-sided cardiac function, 2-dimensional (2-D) and M-mode echocardiography (echo) were performed in 175 subjects, who were classified into 3 groups: group 1-80 normal subjects; group IIA--65 patients with documented right-sided cardiac disease, and group IIB--30 patients with cardiac disease but no right-sided abnormality. The IVC was adequately imaged in 175 of 185 subjects (95%). There was good correlation between M-mode and 2-D echo (r = 0.84) and long- and short-axis (r = 0.88) measurements. The IVC diameter during expiration was: group 1-9 to 28 mm (mean 18.2 +/- 4.6); group IIA--15 to 40 mm (mean 23.1 +/- 4.8) and group IIB-8-24 mm (mean 15.6 +/- 3.7). Collapsibility index (inspiratory decrease in diameter) was: group I-37 to 100% (mean 55.8 +/- 15.9); group IIA--0 to 39% (mean 13.5 +/- 10.5); and group IIB--44 to 100% (mean 60.4 +/- 13.1). A and V waves could be measured in 120 of 151 cases (79%). Both A and V waves were less than 125% of its diameter in group I. The A wave was absent in 34 patients; 30 (88%) were in atrial fibrillation. Among 8 patients with tricuspid regurgitation, 5 (63%) had V waves greater than 125%. There was no correlation between diameter or collapsibility index and age, sex, rhythm or body surface area.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Augmentation of cardiac function by elevation of intrathoracic pressure.

We studied the cardiovascular effects of increasing intrathoracic pressure in an acute pentobarbital-anesthetized canine model of acute ventricular failure induced by large doses of propranolol. Left ventricular (LV) function curves were generated by volume loading from LV filling pressures of 5-20 Torr. The animals were ventilated by using intermittent positive-pressure ventilation with large tidal volumes (30 ml/kg). Chest and abdominal pneumatic binders were used to increase intrathoracic pressure. When compared with the control state, acute ventricular failure was associated with a decrease in the slope of the LV function curves (P less than 0.01). After binding the increase in intrathoracic pressure (1.1 +/- 1.6 to 12.1 +/- 2.4 Torr, P less than 0.01) was associated with an improvement in both right ventricular and LV function. Our study demonstrates that in this model of acute ventricular failure, increasing intrathoracic pressure improves cardiac function. We postulate that this observed improvement with increased intrathoracic pressure is due to reduced LV wall stress in a manner analogous to that seen with arterial vasodilator therapy in congestive heart failure.

Acute Disease↗
PubMed1987

Cardiac function: evaluation with fast-echo MR imaging.

Magnetic resonance (MR) imaging of the heart has, to date, been limited in its ability to evaluate cardiac function. The authors have implemented a technique for functional assessment of the heart using shorter echo times than those generally used for conventional spin-echo imaging. With these short echo times, multiple images can be obtained in a multisection mode approximately within the isovolumetric phases of the cardiac cycle. This permits a pair of image stacks to be obtained, one in end systole and the other in end diastole. With the use of a modified Simpson rule, left ventricular volume and ejection fraction were calculated and compared with results obtained from contrast material-enhanced ventriculography. Preliminary results indicate that this method has promise for the evaluation of a variety of functional parameters in the heart. The short acquisition times for this functional study permit it to be combined with a tissue characterization study within the time constraints of a clinical MR imaging session.

Heart Function Tests↗