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At least 163 records · Page 9Linked to original sources
PubMed2004

Cardiac arrest and cardiopulmonary resuscitation outcome reports: update and simplification of the Utstein templates for resuscitation registries: a statement for healthcare professionals from a task force of the International Liaison Committee on Resuscitation (American Heart Association, European Resuscitation Council, Australian Resuscitation Council, New Zealand Resuscitation Council, Heart and Stroke Foundation of Canada, InterAmerican Heart Foundation, Resuscitation Councils of Southern Africa).

Outcome after cardiac arrest and cardiopulmonary resuscitation is dependent on critical interventions, particularly early defibrillation, effective chest compressions, and advanced life support. Utstein-style definitions and reporting templates have been used extensively in published studies of cardiac arrest, which has led to greater understanding of the elements of resuscitation practice and progress toward international consensus on science and resuscitation guidelines. Despite the development of Utstein templates to standardize research reports of cardiac arrest, international registries have yet to be developed. In April 2002, a task force of the International Liaison Committee on Resuscitation (ILCOR) met in Melbourne, Australia, to review worldwide experience with the Utstein definitions and reporting templates. The task force revised the core reporting template and definitions by consensus. Care was taken to build on previous definitions, changing data elements and operational definitions only on the basis of published data and experience derived from those registries that have used Utstein-style reporting. Attention was focused on decreasing the complexity of the existing templates and addressing logistical difficulties in collecting specific core and supplementary (ie, essential and desirable) data elements recommended by previous Utstein consensus conferences. Inconsistencies in terminology between in-hospital and out-of-hospital Utstein templates were also addressed. The task force produced a reporting tool for essential data that can be used for both quality improvement (registries) and research reports and that should be applicable to both adults and children. The revised and simplified template includes practical and succinct operational definitions. It is anticipated that the revised template will enable better and more accurate completion of all reports of cardiac arrest and resuscitation attempts. Problems with data definition, collection, linkage, confidentiality, management, and registry implementation are acknowledged and potential solutions offered. Uniform collection and tracking of registry data should enable better continuous quality improvement within every hospital, emergency medical services system, and community.

Adult↗
PubMed2006

ACC/AHA/ESC 2006 Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death: a report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (writing committee to develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society.

Explore the source record for details and available documents.

American Heart Association↗
PubMed2001

Ability of new heart rate monitors to measure normal and abnormal heart rate.

BACKGROUND: The extended use of heart rate monitors to non sportive people, and older ones increases the risk to be facing heart rate troubles. Questions exist upon the ability of this devices to detect such abnormalities. The purpose of the investigation was to evaluate the accuracy of two third generation heart rate monitors, Accurex Plus and Vantage NV and to compared these data with those of an older one, PE 4000. Then we investigate responses of this monitors to abnormal heart rate. METHODS EXPERIMENTAL DESIGN: The three heart rate monitors were tested in the laboratory, wired in parallel to an ECG simulator under two modes: a normal heart rate program (7 stable heart rate stages with two marked transitions) and an automatic arrhythmia one. MEASURES: 1st program: Values generated by the ECG simulator were compared to the values produced by the three devices. Particular attention was paid to the transition phases (heart rate drop and heart rate fall). Results of heart rate monitors accuracy were expressed at the exact value (devices value=simulator value) and at approximated value of +/-3 beats x min(-1) (devices value=simulator value +/-3 beats x min(-1)); 2nd program: Abnormal rhythms were analysed using an ambulatory ECG recorder (Synésis) as control data, and compared to the data from the three devices. STATISTICS: Correlation between simulator generated true values and HRMs read values were calculated. RESULTS: In the 1st normal heart rate program, with an accuracy of exact value, Accurex Plus and Vantage NV, were more accurate than the PE 4000 (94% and 89% of values respectively versus 33% for the PE4000). At +/-3 beats x min(-1), the three devices gave good results: over 98% of total values. In transition phases: the three devices showed a smoothing effect, which was stronger in decelerating heart rate than in accelerating heart rate. In the 2nd program: isolated heart rhythm troubles (missing beat, pause <4 sec, supra-ventricular ectopic activity, and ventricular ectopic activity) were either not detected or were rejected. Signal changes such as changes in QRS (ventricular bigeminy) may cause detection losses, and so modify calculated heart rate. The HR signal rising/dropping slopes caused by sudden heart rhythm disorders, were notably attenuated, with a consequent loss of HR accuracy. CONCLUSIONS: In laboratory stable heart rate conditions, third generation HRMs are more accurate than earlier ones. Heart rate monitors are less accurate in transient phases and have not been improved in that domain. The three HRMs ignore isolated heart rate troubles. As expected, the usefulness of HRMs in detecting HR disorders is limited. Nevertheless, these devices have some value with serious troubles, like pause, bradycardia or tachycardia, lasting longer than 4 sec, and especially if they coincide with functional symptoms. The use of such even more accurate devices may consequently be recommended to healthy public for which they were built.

Arrhythmias, Cardiac↗
PubMed2006

Clinical characteristics of emergency department heart failure patients initially diagnosed as non-heart failure.

BACKGROUND: Since previous studies suggest the emergency department (ED) misdiagnosis rate of heart failure is 10-20% we sought to describe the characteristics of ED patients misdiagnosed as non-decompensated heart failure in the ED. METHODS: We analyzed a prospective convenience sample of 439 patients at 4 emergency departments who presented with signs or symptoms of decompensated heart failure. Patients with a cardiology criterion standard diagnosis of decompensated heart failure and an ED diagnosis of decompensated heart failure were compared to patients with a criterion standard of decompensated heart failure but no ED diagnosis of decompensated heart failure. Two senior cardiology fellows retrospectively determined the patient's heart failure status during their acute ED presentation. The Mann-Whitney u-test for two groups, the Kruskall-Wallis test for multiple groups, or Chi-square tests, were used as appropriate. RESULTS: There were 173 (39.4%) patients with a criterion standard diagnosis of decompensated heart failure. Among those with this criterion standard diagnosis of decompensated heart failure, discordant patients without an ED diagnosis of decompensated heart failure (n = 58) were more likely to have a history of COPD (p = 0.017), less likely to have a previous history of heart failure (p = 0.014), and less likely to have an elevated b-type natriuretic peptide (BNP) level (median 518 vs 764 pg/ml; p = 0.038) than those who were given a concordant ED diagnosis of decompensated heart failure. BNP levels were higher in those with a criterion standard diagnosis of decompensated heart failure than in those without a criterion standard diagnosis (median 657 vs 62.7 pg/ml). However, 34.6% of patients with decompensated heart failure had BNP levels in the normal (<100 pg/ml; 6.1%) or indeterminate range (100-500 pg/ml; 28.5%). CONCLUSION: We found the ED diagnoses of decompensated heart failure to be discordant with the criterion standard in 14.3% of patients, the vast majority of which were due to a failure to diagnose heart failure when it was present. Patients with a previous history of COPD, without a previous history of heart failure and with lower BNP levels were more likely to have an ED misdiagnosis of non-decompensated heart failure. Readily available, accurate, objective ED tests are needed to improve the early diagnosis of decompensated heart failure in ED patients.

Journal Article↗
PubMed1993

Factors affecting the species-homologous and species-heterologous binding of mitochondrial ATPase inhibitor, IF1, to the mitochondrial ATPase of slow and fast heart-rate hearts.

We examined the effects of a variety of conditions upon the IF1-mediated inhibition of the ATPase in both intact and sonicated mitochondria and in IF1-depleted submitochondrial particles (SMP) in species-homologous and species-heterologous combinations of IF1 and ATPase. IF1-mediated ATPase inhibition occurred in intact rabbit heart mitochondria at low matrix pH and low membrane potential, but not in intact pigeon and rat heart mitochondria under the same conditions. IF1-mediated ATPase inhibition was, however, demonstrable in both the rabbit and pigeon heart systems in sonicated mitochondria incubated at low ionic strength. The rat heart system failed to exhibit significant IF1-mediated ATPase inhibition in either intact or sonicated mitochondria due to the low amount of IF1 present. When rabbit heart IF1-containing extracts were incubated with IF1-depleted rabbit heart SMP over a range of KCl concentrations, increasing the [KCl] to 100 mM had little effect on IF1-mediated ATPase inhibition. When pigeon heart IF1-containing extracts were incubated with IF1-depleted pigeon heart SMP under the same conditions, increasing [KCl] to 100 mM nearly completely blocked IF1-mediated ATPase inhibition. While the species-endogenous level of rat heart IF1 (i.e., 1x IF1) inhibited IF1-depleted rat heart SMP virtually not at all at any [KCl] examined, the 8x rat heart IF1 was nearly as inhibitory as the 1x rabbit heart IF1 at varying ionic strengths. When rabbit, pigeon, or rat heart IF1 was bound to rabbit versus pigeon IF1-depleted SMP, the effect of varying ionic strength on IF1-mediated ATPase inhibition was related to the species source of the IF1, not to the species source of the enzyme; 1x bovine heart IF1 purified to homogeneity behaved much like 1x crude rabbit heart IF1 when binding to either the rabbit or the pigeon heart enzyme. This suggests that an IF1-ATPase complex stabilizing factor such as has been isolated from baker's yeast cells in neither lacking in the pigeon heart system nor required for the more ionic-strength-resistant binding of IF1 observed in slow heart-rate mammalian heart mitochondria.

Adenosine Triphosphatases↗
PubMed2005

The isolated working heart model in infarcted rat hearts.

Congestive heart failure (CHF) is one of the most common causes of death in western countries. The aim of this study was to establish and validate the working heart model in rat hearts with CHF. In the rat model the animals show parameters and symptoms that can be extrapolated to the clinical situation of patients with end-stage heart failure. The focus of attention was the evaluation of cardiodynamics (e.g.contractility) in the isolated 'working heart' model. The geometric properties of the left ventricle were measured by planimetry (stereology). Formulae available in the past for determining certain parameters in the working heart model (e.g.external heart work) have to be fitted to the circumstances of the infarcted rat hearts with its different organ properties.CHF was induced in Wistar Kyoto (WKY/NHsd) and spontaneously hypertensive rats (SHR/NHsd) by creating a permanent (8 week) occlusion of the left coronary artery, 2 mm distal to the origin from the aorta, by a modified technique (Itter et al. 2004). This resulted in a large infarction of the free left ventricular wall. We were able to establish and adapt a new and predictive working heart model in spontaneously hypertensive rat hearts with myocardial infarction (MI) 8-12 weeks after coronary artery ligation. At this stage the WKY rat did not show any symptoms of CHF. The SHR rat represented characteristic parameters and symptoms that could be extrapolated to the clinical situation of patients with end-stage heart failure (NYHA III-IV). Upon inspection, severe clinical symptoms of CHF such as dyspnoea, subcutaneous oedema, palebluish limbs and impaired motion were prominent. On necropsy the SHR showed lung oedema, hydrothorax, large dilated left and right ventricular chambers and hypertrophy of the septum. In the working heart model the infarcted animals showed reduced heart power, diminished contractility and enhanced heart work, much more so in the SHR/NHsd than in the Wistar Kyoto rat (WKY/NHsd). The aim for the future is to find a causal therapy of heart failure treatment. At present, only palliative therapy is possible for patients with heart failure. For this reason the working heart model in CHF rat hearts should provide a valuable method for early testing of new therapeutic approaches for patients with CHF.

Animals↗
PubMed1998

Fractal dimension and approximate entropy of heart period and heart rate: awake versus sleep differences and methodological issues.

1. Investigations that assess cardiac autonomic function include non-linear techniques such as fractal dimension and approximate entropy in addition to the common time and frequency domain measures of both heart period and heart rate. This article evaluates the differences in using heart rate versus heart period to estimate fractal dimensions and approximate entropies of these time series.2. Twenty-four-hour ECG was recorded in 23 normal subjects using Holter records. Time series of heart rate and heart period were analysed using fractal dimensions, approximate entropies and spectral analysis for the quantification of absolute and relative heart period variability in bands of ultra low (<0.0033 Hz), very low (0. 0033-0.04 Hz), low (0.04-0.15 Hz) and high (0.15-0.5 Hz) frequency.3. Linear detrending of the time series did not significantly change the fractal dimension or approximate entropy values. We found significant differences in the analyses using heart rate versus heart period between waking up and sleep conditions for fractal dimensions, approximate entropies and absolute spectral powers, especially for the power in the band of 0.0033-0.5 Hz. Log transformation of the data revealed identical fractal dimension values for both heart rate and heart period. Mean heart period correlated significantly better with fractal dimensions and approximate entropies of heart period than did corresponding heart rate measures.4. Studies using heart period measures should take the effect of mean heart period into account even for the analyses of fractal dimension and approximate entropy. As the sleep-awake differences in fractal dimensions and approximate entropies are different between heart rate and heart period, the results should be interpreted accordingly.

Adult↗
PubMed1992

Disposition of the atrioventricular conduction tissues in the heart with isomerism of the atrial appendages: its relation to congenital complete heart block.

OBJECTIVES: Our goal was to compare histologically the mechanisms producing congenital complete heart block in normally structured hearts and in hearts with isomerism of the atrial appendages. BACKGROUND: It is known that several different histologic patterns can underscore the existence of congenital complete heart block in the normally structured heart, and that block is particularly frequent in the setting of isomerism of the atrial appendages. The histologic findings in the latter setting were compared and contrasted with those found in the normally structured heart. METHODS: Serial section techniques were used to study 14 hearts with isomerism of the atrial appendage (12 with left isomerism and 2 with right isomerism) and 7 normally structured hearts. RESULTS: Discontinuity between the atrioventricular (AV) node and the ventricular conduction tissues was found in 10 of the 12 hearts with left isomerism; the other 2 hearts had a normally formed conduction axis and heart block was not present in these cases. In both hearts with right isomerism, "slings" of ventricular conduction tissue connected dual AV nodes; congenital complete heart block was not present in either case. In six of the seven cases with a normally structured heart, anti-Ro antibodies had been found in the maternal serum. All six of these hearts had discontinuity between the atrial tissues and the ventricular conduction axis. Intraventricular discontinuity was found in the seventh case, in which anti-Ro antibodies were not found in the mother. CONCLUSIONS: The pattern of congenital complete heart block in cases with left isomerism is discontinuity between the AV node and the conduction axis, in contrast to the pattern of atrial-axis discontinuity produced in the normally structured heart when anti-Ro antibodies are found in the maternal serum.

Abnormalities, Multiple↗
PubMed1997

Simultaneous evaluation of left- and right-sided heart pumping function during dynamic leg exercise in patients with mild chronic congestive heart failure, with special reference to afterload and plasma noradrenaline.

We simultaneously measured increases in mean pulmonary capillary wedge pressure (delta PCW), mean right atrial pressure (delta RA), and cardiac index (delta CI) in response to dynamic leg exercise in 81 patients with mild congestive heart failure to clarify the relationship between the left-sided and right-sided pumping function of the heart. The ratio of delta CI to delta PCW was used as an index of left-sided heart performance and the delta CI/delta RA as an index of right-sided heart performance. We also determined systemic vascular resistance, as an index of afterload on the left heart; pulmonary vascular resistance, as an index of afterload on the right heart; and the plasma level of noradrenaline before and during dynamic leg exercise. Patients with delta CI/delta PCW > 0.181/ min/m2 per mmHg were regarded as having a well functioning left heart, and the patients with delta CI/delta PCW < or = 0.181/min/m2 per mmHg as having a poorly functioning left heart. Patients with delta CI/delta RA > 0.3111/min/m2 per mmHg were regarded as having a well functioning right heart, and those with delta CI/delta RA < or = 0.311/l/min/m2 per mmHg as having a poorly functioning right heart. Patients were classified into three groups: well functioning left and right heart (normal group; n = 40), poorly functioning left and right heart (bilateral group; n = 34), and poorly functioning left heart and well functioning right heart (left-sided group; n = 7). The systemic vascular resistance index decreased during leg exercise in all patients. The decrease was smaller in the bilateral group and the left-sided group than in the normal group. The pulmonary vascular resistance index increased during exercise in the bilateral group but was unchanged in the normal group and the left-sided group. The plasma level of noradrenaline increased during exercise in all patients, but the increase was greater in the bilateral and left-sided groups than in the normal group. Pretreatment with phentolamine, an alpha-adrenoceptor antagonist, inhibited the increase in the pulmonary vascular resistance index and restored the decrease in the systemic vascular resistance index during exercise in the bilateral group. Our results showed that systemic vascular resistance, which represents afterload on the left heart, increased in the presence of impaired left-sided heart pumping function and pulmonary vascular resistance, which represents afterload on the right heart, increased in the presence of impaired right-sided heart pumping function. The inhibited decrease in systemic vascular resistance and the increase in pulmonary vascular resistance during exercise were associated with alpha-adrenoceptor-mediated vasoconstriction caused by the increase in the plasma level of noradrenaline.

Aged↗
PubMed1993

Effect of adenosine on heart rate in isolated muskrat and guinea pig hearts.

The purpose of this study was to compare the responses of isolated hearts of the diving muskrat with the nondividing guinea pig (GP) to determine the contribution of adenosine (ADO) to the profound bradycardia that was seen in isolated muskrat hearts during exposure to hypoxia. Muskrat hearts were more sensitive than GP hearts to the heart rate-lowering effects of exogenously applied ADO or a stable ADO analogue, (R)-N6-(phenylisopropyl)adenosine. The hearts of both species were unpaced, and the bradycardia appeared to be due to high degree of atrioventricular block. Radioligand binding with 8-cyclopentyl-1,3-[3H]dipropylxanthine to A1-ADO receptors was greater in cardiac membranes prepared from GP hearts than from muskrat hearts. Nucleoside transporter antagonist binding was also greater in GP hearts compared with muskrats. This was determined by membrane binding of [3H]-nitrobenzylthioinosine, an antagonist of nucleoside transport. Both muskrat and GP hearts responded to 30 min of hypoxic perfusion by releasing ADO into the coronary effluent; however, the muskrat hearts released approximately five times more than the GP hearts. When hearts were subjected to hypoxia in the presence of ADO deaminase, theophylline, or 8-(p-sulfophenyl)theophylline, the hypoxia-induced bradycardia was blocked in the GP hearts and either slightly reduced or not affected in muskrat hearts. In contrast to GP hearts, muskrat hearts release larger amounts of ADO during hypoxia and are more sensitive to the negative chronotropic effects of exogenously administered ADO; yet the hypoxia-induced bradycardia does not appear to be exclusively mediated by ADO in the muskrat as it is in the isolated GP heart.

Adenosine↗
PubMed1995

Functional and morphologic adaptation of undersized donor hearts after heart transplantation.

OBJECTIVES: This study analyzes our experience with transplantation of small donor hearts in a subgroup of moribund patients who could not be bridged to transplantation with mechanical assist devices. BACKGROUND: The major problem facing transplant programs in the United States is the lack of donor heart availability. One method of expanding the donor pool may be to liberalize the criteria for an acceptable donor heart. METHODS: We analyzed the growth and adaptation of 14 undersized and 14 conventionally sized donor hearts over a period of 10 weeks after heart transplantation. The left ventricular systolic and diastolic diameters, septal and posterior wall thicknesses, left ventricular mass calculated by the Penn convention and left ventricular ejection fraction were obtained by M-mode and two-dimensional echocardiography and documented by a single reader in blinded manner. Echocardiographic measurements were obtained before implantation and at 5 and 10 weeks after orthotopic heart transplantation. RESULTS: The mean (+/- SD) donor/recipient weight ratios were 0.53 +/- 0.06 for undersized hearts and 0.98 +/- 0.05 for normal-sized hearts. All 28 patients received similar immunosuppressive regimens, including intravenous steroids, cyclosporine and azathioprine. The length of hospital stay after transplantation did not vary significantly between the two groups. All the patients had at least one rejection episode during the 10-week study period. There was a tendency toward higher pulmonary pressures in undersized hearts, which was not statistically significant. Heart rate was significantly higher for undersized hearts, due in part to the use of theophylline or terbutaline to maintain tachycardia. There was a significant increase in left ventricular systolic and diastolic dimensions in undersized hearts compared with conventionally sized hearts. Undersized hearts increased in left ventricular mass over the 10-week period, whereas the conventionally sized donor hearts did not change between 5 and 10 weeks. CONCLUSIONS: In undersized hearts the increase in left ventricular mass and internal dimensions, with preservation of the posterior/septal wall thickness ratio, suggests that the left ventricle adapts to the larger recipient circulation early after transplantation. Despite denervation and a mismatched load, undersized transplanted hearts adapt appropriately to their new hemodynamic milieu.

Adaptation, Physiological↗
PubMed1989

Predictability of left heart dysfunction from right heart performance--cardiac index-venous pressure plots and cardiac index-mean pulmonary artery wedge pressure plots at rest and their shift during dynamic exercise.

In an attempt to examine the extent to which the right heart performance can predict the left heart performance in heart diseases primarily affecting the left heart, we recorded cardiac index-venous pressure (CI-VP) plot and cardiac index-mean pulmonary artery wedge pressure (CI-PAW) plot at rest and investigated the shift of CI-VP plot and CI-PAW plot that occurred during mild dynamic exercise of the lower limbs. Six patients had normal heart function and 20 patients had heart diseases primarily affecting the left heart. The sensitivity, specificity, positive predictive value and negative predictive value in the estimation of the left heart function with delta CI/delta VP were 80%, 100%, 89% and 100%, respectively, when delta CI/delta PAW was regarded as the golden standard for the estimation of the left heart function. The sensitivity, specificity, positive predictive value and negative predictive value in estimating the left heart function with delta CI/delta RA were 86%, 93%, 92% and 86%, respectively. When the left heart function was estimated by delta VP alone without measuring delta CI, the sensitivity, specificity positive predictive value and negative predictive value were 40%, 100%, 73% and 100%, respectively. In short, it was possible to predict the left heart dysfunction with delta CI/delta VP or delta CI/delta RA, in the presence of the right heart dysfunction. It was also possible to predict a steep heart slope from normal delta CI/delta VP with error of 2/18 (11%), when steep left heart slope was predicted, based on the presence of steep right heart slope. In comparison, delta VP alone was a less sensitive index of the performance of the left heart.

Adolescent↗
PubMed1989

Occurrence of congenital heart defects in siblings of patients with univentricular heart and tricuspid atresia.

Because of the rarity of univentricular heart and tricuspid atresia, no study of a large number of patients has been made to determine the empiric occurrence risks of a congenital heart defect in their siblings. A retrospective chart review was performed of 223 patients with univentricular heart and 113 with classic tricuspid atresia evaluated from 1982 to 1987. Thirty-four patients with univentricular heart and 17 with tricuspid atresia had no siblings and were excluded. Eleven of the total 388 siblings (2.8%) of the 189 patients with univentricular heart had a congenital heart defect. Of the siblings born after the index case of univentricular heart, 7 of 169 (4.1%) had a congenital heart defect. Two of the 210 siblings (1.0%) of the 96 patients with tricuspid atresia had a congenital heart defect. The patients with univentricular heart were subdivided into 4 groups: (1) double-inlet left ventricle; (2) complex univentricular heart with single or common inlet, or with a ventricle of common or right ventricular morphology; (3) complex univentricular heart with asplenia; and (4) complex univentricular heart with polysplenia. One of the 202 siblings (0.5%) of the 102 patients with double-inlet left ventricle had a congenital heart defect, compared with 7 of the 140 siblings (5.0%) of the 69 patients with complex univentricular heart, 1 of the 29 siblings (3.4%) of the 14 patients with complex univentricular heart and asplenia, and 2 of the 7 siblings (28.6%) of the 4 patients with complex univentricular heart and polysplenia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Mechanisms of ATP conservation during ischemia in slow and fast heart rate hearts.

In the present study we compared the quantitatively most important, Pi-activated mechanisms for conserving ATP during ischemia in dog and rat cardiac muscle. Earlier studies by ourselves showed that dog heart, like all slow heart rate mammalian hearts examined, possesses the ability to inhibit its mitochondrial ATPase by binding IF1, the ATPase inhibitor protein, during ischemia. Rat heart, like other fast heart rate mammalian hearts studied, does not. The present study demonstrated that this IF1-mediated ATPase inhibition in ischemic dog heart, as in other slow heart rate hearts, appears to depend on matrix space acidification mediated largely by Pi-H+ symport via the mitochondrial Pi carrier. The present study further confirmed that maximal glycolytic flux rates are five- to sixfold greater in ischemic rat than in ischemic dog heart. Both of these systems are activated by increasing Pi concentration ([Pi]) during ischemia, and both appear to be regulated somewhat differently in dog than in rat heart. Thus intact dog heart mitochondria exhibited a [Pi]-dependent ATPase inhibition at low external pH, whereas rat heart mitochondria did not. The [Pi] required for maximal ATPase inhibition in dog heart mitochondria was approximately 6 mM. Although both dog and rat heart phosphofructokinase were stimulated by Pi, the enzyme in dog heart was maximally activated by approximately 6 mM Pi, whereas the rat heart enzyme required only approximately 3 mM Pi for its maximal stimulation under otherwise identical conditions. The most active nonmitochondrial ATPase in ischemic dog and rat cardiac muscle, the Ca(2+)-activated actomyosin ATPase, accounted for approximately one-half of the total nonmitochondrial ATPase activity in each species.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗
PubMed1992

Difference of rejection between heart and heart-lung transplantation in rats: flowcytometric analysis of graft infiltrating lymphocyte subsets.

Reported clinical and experimental observations indicate that heart grafts in combined heart-lung transplantation are less frequently rejected than heart grafts transplanted alone. In order to elucidate the mechanism of this difference, twenty-eight inbred male Lewis rats receiving heterotopic allografts from inbred male Fisher rats were evaluated for surface markers of graft infiltrating lymphocytes (GIL) and peripheral blood lymphocytes (PBL) using flowcytometry. Monoclonal antibodies investigated in this study were W3/25 (anti-helper T lymphocyte), OX8 (anti-suppressor/cytotoxic T lymphocyte), OX39 (anti-interleukin 2 receptor), and OX6 (anti-MHC class II antigen). In the acute study, a heart transplanted group (n = 7) and a heart-lung transplanted group (n = 7) without immunosuppression were studied. In the chronic study, cyclosporine (10 mg/kg/day i.m.) were administered in the heart transplanted group (n = 7) and the heart-lung transplanted group (n = 7). Both in the acute and chronic studies, the proportion of W3/25 positive cells in GIL of heart grafts of the heart transplanted group was significantly higher than that of heart grafts and lung grafts of the heart-lung transplanted group. OX8 positive cell proportion in GIL of heart grafts and lung grafts of the heart-lung transplanted group were significantly higher than that of heart grafts of the heart transplanted group. These results lead us to speculate that suppressor T lymphocytes are an important distinguishing factor in the rejection processes of heart allografts and heart-lung allografts as observed in clinical experience.

Animals↗