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PubMed1985

Quantitation of cardiac function by cine-CT.

The recent introduction of a millisecond CT scanner specifically designed for cinematographic real-time imaging of the heart is a significant advance, and its introduction could parallel the impact that cineangiography had on cardiac diagnosis. A major advantage of CT is that central catheterization for angiographic purposes is avoided, as relatively small amounts of intravenous contrast medium provide excellent CT contrast enhancement of the blood pool and cardiac structures. In this article, the cine-CT scanner and the scanning techniques involved are described briefly, and the methods used to analyze CT data are discussed. The initial results are described, as is the potential of cine-CT for quantitating cardiac function.

Cardiac Output↗
PubMed1995

Early abnormalities of cardiac function in non-insulin-dependent diabetes mellitus and impaired glucose tolerance.

The aim of this study was to evaluate the role of diabetes and minor abnormalities of glucose homeostasis, such as impaired glucose tolerance, as determinants of cardiac function and structure in a working population. We studied a population-based sample of 64 telephone company employees (both sexes, mean age 58 years): 25 with normoglycemia, 15 with impaired glucose tolerance, and 24 with non-insulin-dependent diabetes mellitus (NIDDM) diagnosed by oral glucose tolerance test according to the recommendations of the World Health Organization. Subjects with myocardial ischemia were excluded. Left ventricular end-systolic dimension, indexed to body surface area, was greater in those with NIDDM (p < 0.05) and in those with impaired glucose tolerance (p < 0.05) with respect to normoglycemic persons. The ratio of the peak early diastolic velocity wave to the late diastolic wave was lower in those with NIDDM (p < 0.05) and in those with impaired glucose tolerance (p < 0.05) than in participants with normoglycemia. Body mass index and blood pressure were similar in the 3 groups. These results clearly indicate that early abnormalities of cardiac structure and function are observed not only in patients with NIDDM, but also in those with impaired glucose tolerance, independent of the confounding role of myocardial ischemia, body weight, and blood pressure.

Adult↗
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↗
PubMed1996

Depression of cardiac function after deep hypothermic circulatory arrest in deeply anesthetized neonatal lambs.

Cardiac dysfunction is common after neonatal cardiac operations. Previous in vivo studies in neonatal animal models however, have failed to demonstrate decreased left ventricular function after ischemia and reperfusion. Cardiac dysfunction may have been masked in these studies by increased endogenous catecholamine levels associated with the use of light halothane anesthesia. Currently, neonatal cardiac operations are often performed with deep opiate anesthesia, which suppresses catecholamine surges and may affect functional recovery. We therefore examined the recovery of left ventricular function after ischemia and reperfusion in neonatal lambs anesthetized with high-dose fentanyl citrate (450 micrograms/kg administered intravenously). Seven intact neonatal lambs with open-chest preparation were instrumented with left atrial and left ventricular pressure transducers, left ventricular dimension crystals, and a flow transducer. The lambs were cooled (< 18 degrees C) on cardiopulmonary bypass (22 +/- 6 minutes), exposed to deep hypothermic circulatory arrest (46 +/- 1 minutes), and rewarmed on cardiopulmonary bypass (30 +/- 10 minutes). Catecholamine levels and indexes of left ventricular function were determined before (baseline) and 30, 60, 120, 180, and 240 minutes after termination of cardiopulmonary bypass. Levels of epinephrine, norepinephrine, and dopamine were unchanged from baseline values. Left ventricular contractility (slope of end-systolic pressure-volume relationship) was depressed from baseline value (31.7 +/- 9.3 mm Hg/ml) at 30 minutes (15.7 +/- 6.4 mm Hg/ml) and 240 minutes (22.7 +/- 6.4 mm Hg/ml) but unchanged between 60 and 180 minutes. Left ventricular relaxation (time constant of isovolumic relaxation) was prolonged from baseline value (19.0 +/- 3.0 msec) at 30 minutes (31.4 +/- 10.0 msec) and 240 minutes (22.1 +/- 2.8 msec) but unchanged between 60 and 180 minutes. Afterload (left ventricular end-systolic meridional wall stress) was decreased at 30, 60, and 240 minutes. Indexes of global cardiac function (cardiac output, stroke volume), preload (end-diastolic volume), and left ventricular compliance (elastic constant of end-diastolic pressure-volume relationship) were unchanged from baseline values. In deeply anesthetized neonatal lambs exposed to ischemia and reperfusion, left ventricular contractility, relaxation, and afterload are markedly but transiently depressed early after reperfusion and mildly depressed late after reperfusion.

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↗
PubMedDate not supplied

Recovery of cardiac function by long-term left ventricular support in patients with end-stage cardiomyopathy.

Effects of long-term left ventricular (LV) support on end-stage cardiomyopathy patients is unclear. We applied our LV assist system (LVAS) to six heart transplant candidates, aged 17 to 49, with dilated cardiomyopathy, including one dilated phase hypertrophied cardiomyopathy. LVAS was installed between the left atrium and the ascending aorta, and the pump was positioned parecorporeally. In all patients, their general condition improved, and their pump flows were kept at 4 to 5 L/min. Exercise was started after stabilization of their general condition under constant pump flow. Natural heart size and function were examined by echocardiography. In the beginning of assist, all patients showed impaired cardiac function and LV dilation. During LV assist, systolic function measured by ejection time improved in all patients. Left ventricular end-diastolic dimension (LVDd), showed a remarkable decrease in two patients, who were weaned from LVAS after 3 months of support. They are doing well more than 1 year and 3 years after removal; peak VO2 levels (ml/min/kg) were 30 at 1.2 years and 27 at 2.7 years after removal. In the other four patients, however, LVDd had no remarkable changes, and three could not be weaned from LVAS. The last was discontinued from LVAS after 5 months of support because of infection and died 2 months after removal. From this experience, long-term LVAS may provide the chance for recovery of the natural heart in patients with end-stage cardiomyopathy. The patients whose hearts showed remodeling were able to be weaned from LVAS, and their heart function maintained in good condition for several years.

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↗
PubMed2000

Influence of cardiac functional capacity on gender differences in maximal oxygen uptake in children.

OBJECTIVE: To examine the role of gender differences in cardiac functional capacity in explaining higher mean values for maximal oxygen uptake (VO(2)max) in boys than in girls. DESIGN: Comparative group exercise testing. SETTING: Pediatric exercise testing laboratory. SUBJECTS: Twenty-five prepubertal boys (mean [+/- SD] age, 12 +/- 0.4 years) and 24 premenarcheal girls (mean age, 11.7 +/- 0.5 years). INTERVENTIONS: Maximal incremental upright cycle exercise. MEASUREMENTS AND RESULTS: Mean values for VO(2)max were the following: boys, 47.2 +/- 6.1 mL/kg/min; and girls, 40.4 +/- 5.8 mL/kg/min (16.8% difference; p < 0.05). The average maximal stroke index with Doppler echocardiography was 62 +/- 9 mL/m(2) for boys and 55 +/- 9 mL/m(2) for girls (12.7% difference; p < 0.05). No significant gender differences were seen in maximal heart rate or arterial venous oxygen difference. When VO(2)max and maximal stroke volume (SV) were expressed relative to lean body mass, gender differences declined but persisted, falling to 6.2% and 5.2%, respectively. CONCLUSIONS: These findings indicate that differences in SV as well as in body composition contribute to gender-related variations in VO(2)max during childhood. Whether this reflects small gender differences in relative heart size or dynamic factors influencing ventricular preload and contractility during exercise is unknown.

Body Composition↗
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↗
PubMed1997

Effects of wrapping tightness on acute cardiac function in dynamic cardiomyoplasty.

BACKGROUND: It has not been clarified how tightly the heart should be wrapped for maximal augmentation of cardiac function in cardiomyoplasty. METHODS: Hearts in acute failure induced by propranolol were wrapped with the left latissimus dorsi muscle, loosely (loose CMP), moderately (moderate CMP), and tightly (tight CMP) in each of 5 pigs. To measure the pressure between the latissimus dorsi muscle and the left ventricle (LV), a Millar pressure catheter with a latex balloon was placed on the anterior wall of the LV. Left ventricular wall tension was calculated according to Laplace's law, using the difference between the LV pressure and the balloon pressure. RESULTS: In the loose CMP, moderate CMP, and tight CMP groups, the mean balloon pressures during unassisted beats were 8.2, 10.4, and 13.2 mm Hg, respectively. During unassisted beats, the mean LV wall tension values were 38,683, 29,938 (p < 0.05 versus loose CMP), and 26,652 (p < 0.05 versus loose CMP) dynes/cm, respectively, the peak LV pressures were 76.8, 73.8, and 65 (p < 0.05 versus loose CMP) mm Hg, respectively, and the stroke volumes were 12.8, 9.2, and 8.5 (p < 0.05 versus loose CMP) mL, respectively. During assisted beats, the mean LV wall tension values were 20,059, 11,290, and 7,893 (p < 0.05 versus loose CMP) dynes/cm, respectively, the peak LV pressures were 94.1, 98.1, and 92.0 mm Hg, respectively, and the stroke volumes were 13.8, 11.6, and 9.4 (p < 0.05 versus loose CMP) mL, respectively. CONCLUSIONS: During unassisted beats, tight CMP (13 mm Hg) had the advantage of diminishing LV wall tension, but the disadvantage of diminishing LV pressure and stroke volume, compared with loose CMP (8 mm Hg). Moderate CMP (10 mm Hg), however, had the advantage of diminishing LV wall tension without a decrease in LV pressure and stroke volume.

Animals↗
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↗