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The erythrocyte-perfused "working heart" model: hemodynamic and metabolic performance in comparison to crystalloid perfused hearts.

A brief period of ischemia was used to evaluate an erythrocyte-enriched Krebs-Henseleit (KH) buffer (n=8) compared to KH only (n=8) in an isolated working rabbit heart. Experimental protocol was as follows: preischemic baseline, 5 min of global ischemia followed by 45 min of reperfusion. Preischemic heart rate was identical, coronary flow was significantly lower (2.7 versus 5.6 mL/min/g wet wt, p<0.01), the other hemodynamic and biochemical values were significantly higher in erythrocyte-perfused hearts: aortic flow 23.5 versus 12.0, p<0.01; cardiac output 26.2 versus 17.6, p<0.01; all in mL/min/g wet wt; dp/dt max 1286 versus 997 mmHg/s, p<0.01; myocardial oxygen consumption 3.5 versus 2.3 micromol/min/g wet wt, p<0.05. During early reperfusion, in the erythrocyte-perfused hearts, coronary flow further increased (p<0.003), the other hemodynamic parameters returned to baseline values in both groups. High-energy phosphates showed significantly higher values (ATP 2.0+/-0.1 versus 1.3+/-0.1, p<0.05; CrP 2.0+/-0.2 versus 1.6+/-0.1, p<0.05 all in micromol/g wct wt), water content was significantly lower (81% versus 74%, p<0.05) in erythrocyte-perfused hearts. It can be concluded that the erythrocyte-perfused working heart model provides excellent oxygenation, leading to superior hemodynamic and metabolic performance. Additionally, in the erythrocyte-perfused hearts preservation of coronary flow reserve underlines the physiological competency of this preparation.

Adenine Nucleotides↗

Safety and efficacy of carvedilol in severe heart failure. The U.S. Carvedilol Heart Failure Study Group.

BACKGROUND: Many patients remain markedly symptomatic despite optimal current therapy for heart failure. Beta-blockers have often been viewed as contraindicated in this group because of their potential adverse short-term effects on cardiac function. METHODS AND RESULTS: One hundred thirty-one patients with severe congestive heart failure were enrolled into a double-blind, placebo-controlled study of the vasodilating beta-blocker carvedilol. All patients had symptomatic, advanced heart failure while on standard triple therapy, as evidenced by a mean ejection fraction of 0.22, marked reduction in distance traveled in a 6-minute corridor walk test, and severe impairment in quality of life measured by the Minnesota Living With Heart Failure Questionnaire. After a 2-week, open-label test of 6.25 mg twice daily carvedilol, 105 patients were randomized (2:1) to receive either carvedilol (up to 25 mg twice daily, n = 70) or matching placebo (n = 35) for 6 months while background therapy with digoxin, diuretics, and an angiotensin-converting enzyme inhibitor remained constant. Ten patients (8%) did not complete the open-label period because of adverse events and 11.4% in both the carvedilol and placebo groups dropped out in the double-blind phase. The study was terminated early by the Data Safety and Monitoring Board and follow-up evaluation was therefore aborted before the projected number of patients and follow-up time was achieved. Quality of life, which was the primary endpoint, improved similarly in the carvedilol and placebo groups, whereas the global assessment by the physicians and the patient exhibited a better response to carvedilol (P < .05). Hospitalization and mortality rate were too low to evaluate a difference, and exercise time and New York Heart Association classification did not change significantly in response to the drug. Left ventricular ejection fraction rose significantly (+0.09) in the carvedilol group compared with the placebo group (+0.02, P = .004). CONCLUSION: The beta-blocker carvedilol can be safely employed in patients with severe heart failure. Improved left ventricular function with a trend for some improvement in symptoms combined with the experience with the drug in the larger population of less severe patients in this multicenter trial suggests that carvedilol may have a favorable long-term effect in heart failure of diverse severity.

Adrenergic beta-Antagonists↗

Myocardial beta-1 adrenoceptor down-regulation in aging and heart failure: implications for beta-blocker use in older adults with heart failure.

Heart failure is associated with increased sympathetic nervous stimulation that results in down-regulation of myocardial beta-1 receptors. The failing heart might depend more on beta-2 receptors for positive inotropic support than the normal heart. Suppression of both beta-1 and beta-2 adrenoceptors by a non-selective beta-blocker, such as carvedilol, is likely to eliminate the failing heart's much needed inotropic support, resulting in an exacerbation of symptoms. Use of a beta-1 selective blocker, such as metoprolol, on the other hand, is likely to be well tolerated. Unlike carvedilol, the use of metoprolol is associated with up-regulation of beta-1 receptors. The clinical significance of the pharmacodynamic differences between these two beta-blockers in terms of their short-term hemodynamic and long-term beneficial effects is not clearly understood. However, in clinical trials, both carvedilol and metoprolol improved left ventricular function, heart failure symptoms and survival. Both drugs are well tolerated as well. Aging itself is associated with elevated myocardial and serum norepinephrine levels, which is associated with down-regulation of beta-1 receptors. In this article, we reviewed the literature to examine the clinical implications of this dual (age- and heart failure-related) sympathetic stimulation and beta-1 receptor down-regulation on selection of beta-blockers in older adults with heart failure.

Adrenergic beta-Antagonists↗

The use of advanced-age donor hearts adversely affects survival in pediatric heart transplantation.

There is a limited supply of adequate donor hearts for cardiac transplantation. The safety of using advanced-age donor hearts has been debated in adult transplantation but has not been studied previously in pediatric recipients. In this retrospective study, survival of 79 pediatric heart transplant recipients was reviewed. Pediatric recipient groups were stratified based on donor age (group 1 donor age > 40 yr, n = 5; group 2 donor age < or = 40 yr, n = 74). Survival of 267 adolescent (ages 11-17) heart transplant recipients in the United Network for Organ Sharing (UNOS) database was also reviewed. Patients were likewise divided into two groups based on donor age (> 40 yr, n = 12; < or = 40 yr, n = 255). Survival at one yr was 20% in group 1 vs. 78% in group 2 (p < 0.005). Cause of death in all group 1 patients was graft failure secondary to acute rejection. Analysis of risk of death was only significantly attributable to the age of the donor. The increased risk attributable to advanced donor age was also supported by the UNOS data. The UNOS one and two-year Kaplan-Meier survival curves were significantly lower in adolescent patients who received donor hearts > 40 yr of age. One-year survival was 58% (older donors) vs. 85% (younger donors, p < 0.005) and two-year survival was 44% (older donors) vs. 79% (younger donors, p < 0.005). Advanced-age donor hearts should be contraindicated in pediatric transplantation with the exception of critically ill patients who may not be able to wait for a younger heart.

Acute Disease↗

American College of Cardiology/American Heart Association Chronic Heart Failure Evaluation and Management guidelines: relevance to the geriatric practice.

BACKGROUND: Heart failure (HF) is the only cardiovascular disease with increasing incidence and prevalence. Most HF patients are older adults. With the aging of the population and effective treatment of hypertension and coronary artery disease, the two major underlying causes of HF, the number of older Americans with HF is expected to rise significantly in the coming decades. HF is the number one hospital discharge diagnosis for older adults. It is one of the causes of frequent hospital readmissions, reflecting acute decompensation and compromised quality of life for patients and increased cost and resource use for the healthcare system. It is also associated with approximately 300,000 deaths annually, most in older adults. Advances in the management of HF in the past several decades have significantly decreased the mortality and morbidity associated with this condition. Randomized controlled trials have demonstrated the beneficial effects of angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers, beta-blockers, and spironolactone on survival and quality of life of HF patients, but there is evidence of underuse of evidence-based care for HF. Several national guidelines have been published since 1994 that recommended evidence-based evaluation and management of HF. In 1995, the American College of Cardiologists (ACC) and the American Heart Association (AHA) published their first HF guidelines that recommended left ventricular (LV) function evaluation for all patients presenting with HF and use of ACE inhibitors for all patients with LV systolic dysfunction (LVSD) unless contraindicated. The guidelines recommended the use of hydralazine and isosorbide dinitrate in patients who could not use ACE inhibitors. In addition, digoxin was recommended in patients with HF due to LVSD but not adequately responsive to ACE inhibitors and diuretics and in those with atrial fibrillation and rapid ventricular rates. Diuretic use was recommended for symptomatic patients with evidence of fluid overload. Use of anticoagulation was restricted to patients with atrial fibrillation or to those with a history of systemic or pulmonary embolism. Beta-blockers were reserved for HF patients after acute myocardial infarctions. Recent advances in the management of HF called for a revision of the guidelines. PURPOSE: The purpose of revising the 1995 ACC/AHA guidelines was to incorporate recent advances in pharmacological and nonpharmacological approaches to HF treatment and to assist physicians in clinical decision-making in the management of HF. METHODS: The ACC/AHA invited representatives from the American College of Chest Physicians, the Heart Failure Society of America, the International Society for Heart and Lung Transplantation, the American Academy of Family Physicians, and the American College of Physicians-American Society of Internal Medicine to participate in the preparation of the guidelines. The writing committee searched pertinent medical literature in English using computerized databases such as MEDLINE and EMBASE and manually searching the bibliographies of the selected articles. The writing committee classified HF into four stages, including patients who are at high risk for developing HF. According to this new classification, Stage A and B represent asymptomatic patients, the former at high risk for developing HF but no structural disorder, the latter with structural disorders of the heart. Stage C encompasses patients with underlying structural heart disorders who are symptomatic, either currently or in the past. Stage D includes end-stage HF patients. This new classification is intended to complement the New York Heart Association (NYHA) functional classification of HF into Class I (asymptomatic), Class II (symptomatic on less than ordinary exertion), Class III (symptomatic on ordinary exertion), and Class IV (symptomatic at rest). RESULTS: The recommendations are categorized into those for evaluation and management.

Adrenergic beta-Antagonists↗

Heart rate versus heart rate variability in risk prediction after myocardial infarction.

INTRODUCTION: The aim of this study was to evaluate and compare heart rate and heart rate variability (HRV) in risk prediction after acute myocardial infarction (MI) and to evaluate the effect of beta-blocker treatment on the prognostic performance of heart rate and HRV. METHODS AND RESULTS: Three hundred sixty-six patients underwent 24-hour Holter recording 1 to 6 days after an MI. HRV was expressed as the standard deviation of all normal-to-normal intervals. Left ventricular systolic function was evaluated using the wall motion index. Half of the patients were taking a beta-blocker at the time of Holter recording. Mean follow-up was 44 months (median 34) after MI. By the end of follow-up, 82 patients had died. Mortality at 1 and 3 years was 12.5% and 22.6%, respectively. HRV, heart rate, wall motion index, number of ventricular premature beats per hour, and ventricular tachycardia were all significantly (P < 0.05) associated with mortality in univariate analysis, independent of beta-blocker therapy. In multivariate Cox analysis, only heart rate, wall motion index, number of ventricular premature beats per hour, and age had independent prognostic value (P < 0.001). In any model, including heart rate, HRV had no predictive value. CONCLUSION: The prognostic information of HRV is contained completely in heart rate, which carries prognostic information further than that of HRV. This result was independent of beta-blocker treatment.

Adrenergic beta-Antagonists↗

Heart rate variability and ischaemia in patients with coronary heart disease and stable angina pectoris; influence of drug therapy and prognostic value. TIBBS Investigators Group. Total Ischemic Burden Bisoprolol Study.

AIMS: Determination of the influence of therapy with bisoprolol and nifedipine on the heart rate variability of patients from the Total Ischemic Burden Bisoprolol Study and examination of the prognostic value. METHODS AND RESULTS: Four hundred and twenty-two patients with stable angina were included. The heart rate variability was determined over a period of 24 h. Parameters determined: standard deviation of the mean of all corrected RR intervals, standard deviation of all 5 min mean cycle lengths, square root of the mean of the squared differences of successive corrected RR intervals. Nifedipine reduced the mean values of all heart rate variability parameters tested. Square root of the mean of the square differences of successive corrected RR intervals increased under bisoprolol. Standard deviation of the mean of all corrected RR intervals and standard deviation of all 5 min mean cycle lengths increased from low baseline values and declined from higher baseline values. The increase in heart rate variability under therapy was accompanied by a tendency towards a better prognosis. Patients with an increase in heart rate variability and simultaneous complete suppression of ischaemia under therapy displayed no serious events in the course of one year. CONCLUSIONS: The increase in the heart rate variability, which can be regarded as prognostically favourable, was predominantly observed under bisoprolol. The parameter constellation of an increase in heart rate variability and complete ischaemia suppression on the 48-h Holter ECG was associated with the greatest benefit.

Adrenergic beta-Antagonists↗

Randomized, controlled trial of integrated heart failure management: The Auckland Heart Failure Management Study.

AIMS: To determine the effect of an integrated heart failure management programme, involving patient and family, primary and secondary care, on quality of life and death or hospital readmissions in patients with chronic heart failure. METHODS AND RESULTS: This trial was a cluster randomized, controlled trial of integrated primary/secondary care compared with usual care for patients with heart failure. The intervention involved clinical review at a hospital-based heart failure clinic early after discharge, individual and group education sessions, a personal diary to record medication and body weight, information booklets and regular clinical follow-up alternating between the general practitioner and heart failure clinic. Follow-up was for 12 months. One hundred and ninety-seven patients admitted to Auckland Hospital with an episode of heart failure were enrolled in the study. There was no significant difference between the intervention and control groups for the combined end-point of death or hospital readmission. The physical dimension of quality of life showed a greater improvement in the intervention group from baseline to 12 months compared with the control group (-11.1 vs -5.8 respectively, 2 P=0.015). The main effect of the intervention was attributable to the prevention of multiple admissions (56 intervention group vs 95 control group, 2 P=0.015) and associated reduction in bed days. CONCLUSIONS: This integrated management programme for patients with chronic heart failure improved quality of life and reduced total hospital admissions and total bed days.

Adult↗

Effects of subchronic exposures to concentrated ambient particles (CAPs) in mice. III. Acute and chronic effects of CAPs on heart rate, heart-rate fluctuation, and body temperature.

Normal mice (C57) and mice prone to develop atherosclerosis (ApoE-/-) were implanted with electrocardiograph (EKG), core body temperature, and motion transmitters were exposed daily for 6 h to Tuxedo, NY, concentrated ambient particles (CAPs) for 5 day/wk during the spring and summer of 2003. The series of 5-min EKG monitoring and body-temperature measurements were obtained for each animal in the CAPs and filtered air sham exposure groups. Our hypothesis was that chronic exposure could cause cumulative health effects. We used our recently developed nonparametric method to estimate the daily time periods that mean heart rates (HR), body temperature, and physical activity differed significantly between the CAPs and sham exposed group. CAPs exposure most affected heart rate between 1:30 a.m. and 4:30 a.m. With the response variables being the average heart rate, body temperature, and physical activity, we adopted a two-stage modeling approach to obtain the estimates of chronic and acute effects on the changes of these three response variables. In the first stage, a time-varying model estimated daily crude effects. In the second stage, the true means of the estimated crude effects were modeled with a polynominal function of time for chronic effects, a linear term of daily CAPs exposure concentrations for acute effects, and a random component for unknown noise. A Bayesian framework combined these two stages. There were significant decreasing patterns of HR, body temperature, and physical activity for the ApoE-/- mice over the 5 mo of CAPs exposure, with smaller and nonsignificant changes for the C57 mice. The chronic effect changes of the three response variables for ApoE-/- mice were maximal in the last few weeks. There was also a significant relationship between CAPs exposure concentration and short-term changes of heart rate in ApoE-/- mice during exposure. Response variables were also defined for examining fluctuations of 5-min heart rates within long (i.e., 3-6 h) and short time periods (i.e., approximately 15 min). The results for the ApoE-/- mice showed that heart-rate fluctuation within the longer periods increased to 1.35-fold by the end of exposure experiment, while the heart-rate fluctuation within 15 min decreased to 0.7-fold.

Air Pollutants↗

Pulmonary function in chronic heart failure. Changes after heart transplantation.

To investigate the impact of chronic heart failure on pulmonary function in heart transplant recipients, pulmonary function was evaluated in 41 consecutive patients (mean age 43 years, range 15-57 years) before and 6 months after successful heart transplantation. The pulmonary function tests included measurements of forced vital capacity [FVC], forced expiratory volume in 1.s [FEV1], FEV1/FVC ratio, total lung capacity [TLC], and diffusion capacity for carbon monoxide [TLCO] and KCO [TLCO per l alveolar volume]. Compared to pretransplant values, spirometry after transplantation revealed modest improvements in FVC (from 77 +/- 16 to 88 +/- 21% of predicted [%pred]; p < 0.001) and FEV1 (from 75 +/- 16 to 85 +/- 22%pred; p < 0.001), whereas the FEV1/FVC ratio was unchanged (81% +/- 11 and 80% +/- 10; p = NS). A slight but statistically significant increase in TLC (from 78 +/- 15 to 86 +/- 18%pred, p < 0.001) was also observed. Prior to transplantation the mean TLCO was 76 +/- 17%pred; 7 of the patients had a TLCO below 60%pred (mean 51% pred). In 33 of the 41 patients a reduction in TLCO was observed after transplantation; for all 41 patients the mean fall in TLCO was 14% of the predicted value (SD 12%pred) (p < 0.0001). Likewise, a significant reduction in KCO was noted (p < 0.0001). Multiple regression analysis revealed that high pretransplant TLCO %pred (p = 0.02) and FVC %pred (p = 0.04) were associated with a less favorable outcome concerning posttransplant TLCO %pred. Although normalization of FEV1, FVC and TLC can be anticipated after correction of severe chronic left ventricular failure by heart transplantation, the pronounced concomitant decline in diffusion capacity observed in this study may be explained by underlying pulmonary disease caused by factors other than long-standing heart failure. Our findings support the notion that pulmonary function abnormalities attributable to chronic heart failure should not preclude consideration for heart transplantation.

Adolescent↗

Spectral analysis of heart rate indicates reduced baroreceptor-related heart rate variability in elderly persons.

Spectral analysis of the cardiac interbeat interval was used to examine baroreceptor-related supine and standing heart rate variability (HRV) in young (less than 40 years of age) and elderly (greater than 60 years of age) healthy volunteers. Heart rates and blood pressures were examined also. When supine, average heart rate, systolic and diastolic blood pressure, and HRV for the young volunteers were 66.5 bpm, 113.0/64.3 mmHg, and 5.74 log units of relative power, respectively. The same values for the elderly group were 65.4 bpm, 126.3/74.0 mmHg, and 4.43 log units. Statistical analysis revealed that, compared to the young volunteers, supine elderly volunteers had similar heart rates, higher blood pressures, and lower baroreceptor HRV. There was little change in blood pressure in either group upon standing. However, upon standing, heart rate increased 17.7 bpm and baroreceptor HRV increased to 6.58 (+ 14.6%) in the younger volunteers. This was significantly different from the elderly volunteers, whose heart rate increased by only 10.9 bpm and their HRV to 4.72 (+ 6.5%). These results indicate that much of the reduction in HRV in old age results from decreases in baroreceptor modulation of heart rate. In addition, the difference between young and old persons is greatest in the standing position because elderly individuals exhibit less recruitment of baroreceptor activity with postural change.

Adult↗

Synergistic effects of mycophenolate mofetil and sirolimus in prevention of acute heart, pancreas, and kidney allograft rejection and in reversal of ongoing heart allograft rejection in the rat.

BACKGROUND: The effect of mycophenolate mofetil (MMF) and sirolimus (rapamycin, RAPA) mono- and combination-therapy was examined in prevention of acute heart, pancreas, and kidney allograft rejection and in reversal of ongoing heart allograft rejection in the rat. METHODS: Both drugs were administered orally for up to 30 days. Eleven groups (n=6) were involved in the first part of the heart allografting model. Brown Norway (RT1n) to Lewis (RT1(1)) combination was used in the heart and pancreas transplantation models, whereas Buffalo (RT1b) to Wistar Furth (RT1u) was used in the kidney transplantation model. RESULTS: The naive control group showed a mean survival time of 6.5+/-0.6 days. There were graded dose-responses to monotherapy of MMF 10 and 20 mg(kg/ day (12.5+/-2.6 days; 19.3+/-9.0 days) and RAPA 0.2, 0.4, 0.8, and 1.8 mg/kg/day (19.2+/-2.0 days; 30.0+/-7.3 days; 50.8+/-12.5 days; 51.2+/-2.6 days), respectively (P=0.001). Results with the combined use of drugs indicate that a synergistic or very strong synergistic interaction was produced when compared with monotherapy of MMF or RAPA: MMF 10 mg(kg/day+RAPA 0.2 mg/kg(day (52.7+/-5.7 days, combination index [CI] =0.189), MMF 20 mg(kg/day+RAPA 0.2 mg/kg/day (57.7+/-5.7 days, CI=0.084), MMF 10 mg/kg/day+RAPA 0.4 mg(kg/day (50.2+/-13.5 days, CI=0.453), and MMF 20 mg/kg(day+ RAPA 0.4 mg/kg(day (51.5+/-6.8 days, CI=0.439), respectively. These results were repeatable in the prevention of acute pancreas and kidney allograft rejection in the rat. In the second part of the study of reversal of ongoing acute heart allograft rejection model, the combined treatment of MMF 10 mg/kg(day+RAPA 0.2 mg/ kg(day (35.5+/-16.0 days, CI=0.794) and MMF 20 mg/kg day+RAPA 0.2 mg(kg/day (57.2+/-4.7 days, CI=0.310) represented synergistic interaction compared with monotherapy of MMF or RAPA. CONCLUSIONS: Concomitant therapy of MMF and RAPA produces a synergistic effect in prevention of heart, pancreas, and kidney allograft rejection and in reversal of ongoing heart allograft rejection in the rat.

Acute Disease↗

Synergistic effects of malononitrilamides (FK778, FK779) with tacrolimus (FK506) in prevention of acute heart and kidney allograft rejection and reversal of ongoing heart allograft rejection in the rat.

BACKGROUND: The effects of tacrolimus (FK506) and malononitrilamides (MNA) (FK778 and FK779) monotherapy and combination therapy were examined in prevention of acute heart and kidney allograft rejection and reversal of ongoing acute heart allograft rejection in the rat. METHODS: Brown Norway (RT1n)-to-Lewis (RT11) and ACI (RT1a)-to-Lewis (RT11) combinations were used, respectively, for heart and kidney transplantation models. Immunosuppressants were administered orally from day 1 to day 14 for preventing acute rejection and from day 4 to day 34 after transplantation for the reversal of ongoing acute rejection. RESULTS: In the prevention of acute heart rejection model, recipient rats treated with monotherapy of tacrolimus or MNA (FK778, FK779) showed a dose-related prolongation of mean survival time (MST) compared with naive control rats (P<0.01). The mean survival time in combination therapy of tacrolimus (FK506) and FK778 indicated that an additive to synergistic interaction was produced when compared with the respective monotherapies (combination index [CI]=0.631-1.022). These results were reproducible with tacrolimus and FK779 combination therapy (CI=0.572-0.846). Furthermore, similar results were also found in the prevention of acute kidney allograft rejection in the rat (CI=0.137-0.516). In the reversal of ongoing acute heart allograft rejection, combination therapy of tacrolimus and FK778 demonstrated a strong synergistic interaction (CI=0.166-0.970) compared with monotherapy of tacrolimus or FK778. CONCLUSIONS: Combination therapy of tacrolimus and MNA (FK778, FK779) produces synergistic effects in prevention of acute heart and kidney rejection and reversal of ongoing heart allograft rejection in the rat.

Acute Disease↗

Pharmacotherapy in congestive heart failure: drug absorption in the management of congestive heart failure: loop diuretics.

Congestive heart failure is a disease state distinguished by the regular presence of both renal and hepatic abnormalities in drug handling. One such abnormality involves flaws in the process of drug absorption. In most instances, congestive heart failure-related abnormalities in drug absorption are of inconsequential significance. However, this is not the case with loop diuretics. Loop diuretic action ordinarily tracks the rate and extent of absorption if a sufficient amount of diuretic has been given to exceed the threshold for diuretic effect. In congestive heart failure, both the rate and absolute amount of loop diuretic absorbed can be reduced as a function of the heart failure state itself. In this setting, drug dissolution characteristics can assume added significance. Furosemide is the loop diuretic with the widest intra- and interpatient variability of absorption. Alternatively, the loop diuretic torsemide is rapidly and fairly completely absorbed independent of the heart failure state. This pattern of absorption establishes it as the preferred loop diuretic in the otherwise diuretic-resistant heart failure patient. However, the exact role of torsemide in the outpatient management of congestive heart failure remains to be determined.

Diuretics↗

Correction for heart rate is not necessary for QT dispersion in individuals without structural heart disease and patients with ventricular tachycardia.

BACKGROUND: It remains controversial whether QT dispersion should be corrected for heart rate, especially when the limitations of rate correction formulae are considered. We investigated whether incremental atrial pacing affects QT dispersion and the rate-corrected values according to Bazett's formula in individuals without structural heart disease and in patients with history of sustained ventricular tachycardia. METHODS: We studied 32 individuals without structural heart disease (group A), and 16 patients with a history of sustained ventricular tachycardia (group B). QT dispersion and corrected for heart rate QT dispersion using Bazett's formula (QTc dispersion) were calculated in sinus rhythm, and during continuous right atrial pacing for one minute at 100 and 120 beats/min. RESULTS: Interobserver variability was not significant (P > or = 0.10). QT dispersion did not differ at rest between groups A and B and did not change significantly from baseline at any heart rate in both groups. However, QTc dispersion increased significantly with atrial pacing in a similar manner in group A and group B (42 +/- 19 ms at rest vs 53 +/- 23 ms at 120 beats/min, P < 0.001 for group A, 39 +/- 16 ms at rest vs 60 +/- 19 ms at 120 beats/min, P < 0.001 for group B). CONCLUSIONS: We conclude that QT dispersion remains unchanged during atrial pacing at heart rates up to 120 beats/min in both individuals without structural heart disease and in patients with a history of sustained ventricular tachycardia. Correction by Bazett's formula results in prolongation of QTc dispersion, yielding values which may be misleading.

Adolescent↗

Optimal management of outpatients with heart failure using advanced practice nurses in a hospital-based heart failure center.

PURPOSE: To examine the benefits of an advanced practice nurse (APN) driven, hospital-based heart failure center. DATA SOURCES: Selected multidisciplinary studies, review articles, Heart Failure Society of America practice guidelines, and American College of Cardiology/American Heart Association clinical practice guidelines. CONCLUSIONS: APN specialists in this hospital-based heart failure center provide heart failure patients with high quality multidisciplinary health care in a single environment, which leads to optimal outcomes. Patients experience positive outcomes as evidenced by spared hospitalizations, improved scores on the Minnesota Living With Heart Failure Survey, and the 6-min walk. IMPLICATIONS FOR PRACTICE: APNs with prescriptive authority can effectively direct heart failure care for outpatients by utilizing multidisciplinary resources of the hospital. Treatment strategies include titrating medication, frequent symptom monitoring, tracking medication and dietary compliance, telemonitoring, and providing aggressive multidisciplinary education. This approach is highly effective for reducing hospital readmissions as well as for improving quality of life and functional status for outpatients with left ventricular systolic dysfunction.

Clinical Competence↗

Relationships between heart score, heart weight and body weight in Greyhound dogs.

The aim of this study was to determine the relationships between heart score (mean QRS interval), heart weight and body weight in Greyhound dogs. Highly significant correlations between these measurements have been observed and distinct sex differences have been demonstrated. The results of multiple regression analysis indicated that 66% of the variation in heart weight was due to variation in heart score and body weight. From the regression analysis, a formula for heart weight prediction with a standard deviation of 27.1 g was derived. The implications of these findings have been discussed briefly and emphasis has been placed on the need for good electrocardiographic technique, if the procedures outlined are to be used successfully. The positive correlation between heart score and heart size demonstrated here in Greyhounds is in accord with similar correlations reported previously in racehorses and human athletes.

Animals↗

Ischemic heart disease and heart weight.

Separate weights for heart ventricle walls and interventricular septa were analyzed in 110 hearts with autopsy findings of ischemic heart disease (coronary atherosclerosis, recent or old myocardial infarcts) and with no other cardiac or systemic causes of cardiac enlargement. In hearts with coronary atherosclerosis alone (without old or recent myocardial infarcts) no weight increase was observed in the left ventricle when compared to 29 controls. Patients having infarcts associated with nonstenosing atherosclerosis (less than 50% of the luminal diameter narrowed) of the coronaries had normal heart weights as well. On the contrary, infarcts associated with stenosing coronary sclerosis (narrowing more than 50%) showed significant signs of left ventricular weight increase, which is interpreted as compensatory heart hypertrophy. The greatest degree of hypertrophy was observed in hearts with left ventricular aneurysms.

Coronary Disease↗