bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elevated concentrations of endogenous ouabain in patients with congestive heart failure.
Authors: Gottlieb S S , Rogowski A C , Weinberg M , Krichten C M , Hamilton B P , Hamlyn J M 
Published: June 2012

BACKGROUND
An endogenous digitalis-like compound in mammals has long been postulated, but only recently has a substance indistinguishable from ouabain been identified in human plasma. Because of the potential significance of such a substance in patients with congestive heart failure, we sought to evaluate the pathophysiology of endogenous ouabain in these individuals.

METHODS AND RESULTS
Using an immunoassay, we determined plasma ouabain concentrations in 51 patients with heart failure and in 19 control subjects. Plasma ouabain concentrations in control subjects ranged from 0.16 to 0.77 nM (mean, 0.44 +/- 0.20 nM). In 19 matched heart failure patients receiving digoxin, the mean ouabain was significantly elevated at 1.59 +/- 2.2 nM (range, 0.17-8.76 nM, p less than 0.05 versus control subjects). The ouabain concentration correlated inversely with both cardiac index (r = -0.62, p less than 0.005) and mean arterial pressure (r = -0.51, p less than 0.05). However, there was no correlation between ouabain and left ventricular filling (r = 0.19, NS) or right atrial pressures (r = 0.20, NS). In 16 heart failure patients not receiving digoxin, the mean ouabain was 1.52 +/- 2.58 nM. No relation between renal function and ouabain was detected.

CONCLUSIONS
The unanticipated lack of correlation of ouabain with atrial pressures indicates that volume is not the chief determinant of ouabain concentration in patients with congestive heart failure. However, the significant relations of plasma ouabain concentration with cardiac index and mean arterial pressure imply that endogenous ouabain may be an important homeostatic factor in humans.
Effects of the angiotensin converting enzyme inhibitor enalapril on the long-term progression of left ventricular dysfunction in patients with heart failure. SOLVD Investigators.
Authors: Konstam M A , Rousseau M F , Kronenberg M W , Udelson J E , Melin J , Stewart D , Dolan N , Edens T R , Ahn S , Kinan D 
Published: June 2012

BACKGROUND
In patients with heart failure, activation of the renin-angiotensin system is common and has been postulated to provide a stimulus for further left ventricular (LV) structural and functional derangement. We tested the hypothesis that chronic administration of the angiotensin converting enzyme (ACE) inhibitor enalapril prevents or reverses LV dilatation and systolic dysfunction among patients with depressed ejection fraction (EF) and symptomatic heart failure.

METHODS AND RESULTS
We examined subsets of patients enrolled in the Treatment Trial of Studies of Left Ventricular Dysfunction (SOLVD). Fifty-six patients with mild to moderate heart failure underwent serial radionuclide ventriculograms, and 16 underwent serial left heart catheterizations, before and after randomization to enalapril (2.5-20 mg/day) or placebo. At 1 year, there were significant treatment differences in LV end-diastolic volume (EDV; p less than 0.01), end-systolic volume (ESV; p less than 0.005), and EF (p less than 0.05). These effects resulted from increases in EDV (mean +/- SD, 136 +/- 27 to 151 +/- 38 ml/m2) and ESV (103 +/- 24 to 116 +/- 24 ml/m2) in the placebo group and decreases in EDV (140 +/- 44 to 127 +/- 37 ml/m2) and ESV (106 +/- 42 to 93 +/- 37 ml/m2) in the enalapril group. Mean LVEF increased in enalapril patients from 0.25 +/- 0.07 to 0.29 +/- 0.08 (p less than 0.01). There was a significant treatment difference in LV end-diastolic pressure at 1 year (p less than 0.05), with changes paralleling those of EDV. The time constant of LV relaxation changed only in the placebo group (p less than 0.01 versus enalapril), increasing from 59.2 +/- 8.0 to 67.8 +/- 7.2 msec. Serial radionuclide studies over a period of 33 months showed increases in LV volumes only in the placebo group. Two weeks after withdrawal of enalapril, EDV and ESV increased to baseline levels but not to the higher levels observed with placebo.

CONCLUSIONS
In patients with heart failure and reduced LVEF, chronic ACE inhibition with enalapril prevents progressive LV dilatation and systolic dysfunction (increased ESV). These effects probably result from a combination of altered remodeling and sustained reduction in preload and afterload.
Coronary angioplasty in cardiac transplant patients. Results of a multicenter study.
Authors: Halle A A , Wilson R F , Massin E K , Bourge R C , Stadius M L , Johnson M R , Wray R B , Young J B , Davies R A , Walford G D 
Published: June 2012

BACKGROUND
Accelerated allograft atherosclerosis is the main cause of death of cardiac transplant recipients after the first year after transplantation. Because no medical therapy is known to prevent or retard graft atherosclerosis and transplantation is associated with a shortened allograft survival, alternative, palliative therapy with percutaneous transluminal coronary angioplasty (PTCA) has been attempted. Because no single medical center has performed angioplasty in a large number of cardiac transplant recipients, representatives of 11 medical centers retrospectively analyzed their complete experience of coronary angioplasty in cardiac transplant patients to determine the safety, efficacy, limitations, and long-term outcome of angioplasty in allograft coronary vascular disease.

METHODS AND RESULTS
Thirty-five patients underwent 51 angioplasty procedures for 95 lesions 46 +/- 5 months (mean +/- SEM) after transplantation. The primary indications for angioplasty included angiographic coronary disease in 22 cases (43%) and noninvasive evidence of ischemia in 18 procedures (35%). Angiographic success, defined as less than or equal to 50% post-PTCA stenosis, occurred in 88 of 95 lesions (93%). Mean pre-PTCA stenosis was 83 +/- 1.1%; mean post-PTCA stenosis was 29 +/- 2.1% (p less than 0.0001). Periprocedural complications included myocardial infarction and late in-hospital death in one patient and three groin hematomas. Twenty-three of the 35 patients (66%) had no major adverse outcome such as death, retransplantation, or myocardial infarction at 13 +/- 3 months after angioplasty. Four patients died less than 6 months after angioplasty, and four died more than 6 months after angioplasty (range, 6-23 months). Two patients had retransplantation 2 months after PTCA, and one patients had retransplantation 18 months after angioplasty.

CONCLUSIONS
Coronary angioplasty may be applied in selected cardiac transplant recipients with comparable success and complication rates to routine angioplasty. Whether angioplasty prolongs allografts survival remains to be determined by a prospective, controlled trial.
Plasma atrial natriuretic peptide is unstable under most storage conditions.
Authors: Nelesen R A , Dimsdale J E , Ziegler M G 
Published: June 2012

BACKGROUND
Atrial natriuretic peptide (ANP) is a hormonal regulator of cardiovascular fluid volume. More than 1,000 scientific articles were written about ANP between 1987 and 1991. Because some articles hinted at problems with storing ANP, this study examined the effect of numerous techniques for storing and processing human ANP samples.

METHODS AND RESULTS
Samples were obtained repeatedly from three patients, treated, and stored under a variety of conditions. Experiment 1 evaluated the effects of different preservatives at 35, 21, 14, 10, and 7 days before assay. Experiment 2 evaluated nonspecific binding of ANP to different storage tubes during 28 days of storage. Experiment 3 evaluated the effect of storage at -20 degrees C, -80 degrees C, and -196 degrees C for 1 month. ANP was very unstable, degrading as much as 30% after 3 days of storage and by more than 50% in 1 month even when stored at -80 degrees C. Only storage at -196 degrees C (in liquid nitrogen) kept ANP stable for 1 month. Extraction and lyophilization of the samples before freezing and assay within 7 days of freezing only partially minimized the amount of degradation. All other processing techniques had little effect on slowing the degradation of ANP.

CONCLUSIONS
These findings raise disturbing questions about the interpretation of the substantial literature on ANP.
Lipoprotein(a) is an independent risk factor for cardiovascular disease in hemodialysis patients.
Authors: Cressman M D , Heyka R J , Paganini E P , O'Neil J , Skibinski C I , Hoff H F 
Published: June 2012

BACKGROUND
Although serum lipoprotein(a) [Lp(a)] is an independent risk factor for atherosclerosis in the general population and Lp(a) levels are increased in hemodialysis patients, an association of Lp(a) with the risk of clinical events attributed to atherosclerosis has not been established in the chronic hemodialysis patient population. We therefore determined the association between Lp(a) levels and the risk of clinical events of presumed atherosclerotic etiology in a prospective study of an outpatient hemodialysis population.

METHODS AND RESULTS
Lp(a) was measured by radioimmunoassay in a baseline cardiovascular disease risk assessment in a consecutive series of 129 hemodialysis patients. The relation between baseline Lp(a) and clinical events of presumed atherosclerotic etiology was determined during 48 months of follow-up. Hemodialysis patients had a median Lp(a) concentration that was approximately four times as high as the median Lp(a) concentration in normal controls and twice as high as the levels in controls with angiographic evidence of coronary artery disease [median Lp(a), 38.4 versus 16.9 mg/dl; p less than 0.001]. Baseline Lp(a) levels were no different in participants with or with no history of a previous clinical event at the time of the baseline examination. However, baseline Lp(a) concentration (p less than 0.001) and a history of atherosclerotic clinical events (p = 0.001) were associated with clinical events during the period of follow-up. In contrast, baseline serum total cholesterol, triglyceride, high density lipoprotein cholesterol, low density lipoprotein cholesterol, age, gender, race, or duration of hemodialysis were unrelated to this risk in the prospective study. Stepwise multiple logistic regression analysis demonstrated that serum Lp(a) concentration (p = 0.001) and the presence of a previous clinical event (p = 0.004) were the only independent contributors to the risk of a clinical event during the period of follow-up.

CONCLUSIONS
Lp(a) is an independent risk factor for clinical events attributed to atherosclerotic cardiovascular disease in patients receiving chronic hemodialysis treatment of end-stage renal disease.
Mechanism of double potentials recorded during sustained atrial flutter in the canine right atrial crush-injury model.
Authors: Feld G K , Shahandeh-Rad F 
Published: June 2012

BACKGROUND
During atrial flutter, double potentials may be recorded at specific sites in the atria. It has been suggested that double potentials represent sequential activations at the center of the reentrant circuit. An alternative hypothesis is that double potentials represent electrical activity in an area of slow conduction. Understanding their mechanism is important because double potentials have been considered a possible indicator of target sites for catheter ablation.

METHODS AND RESULTS
We systematically studied double potentials in our canine model of atrial flutter produced by right atrial crush injury using a 64-channel computerized mapping system with 56 electrodes on the right atrium in seven mongrel dogs under general anesthesia. Activation maps were recorded during sinus rhythm before and after crush injury, during rapid pacing above and below the crush injury, and during sustained atrial flutter, entrainment of atrial flutter, and termination of atrial flutter induced with D-sotalol (2 mg/kg). During sinus rhythm before crush injury, activation was uniform, and double potentials were not recorded in any dog. After crush injury, activation proceeded up to and around the crush injury, and narrowly split double potentials were recorded in two of seven dogs. During rapid pacing above and below the crush injury, double potentials were recorded in five dogs. During 14 episodes of atrial flutter (mean cycle length, 140 +/- 16 msec), double potentials were recorded at electrodes along the crush injury. The activation time of the early x component of the double potentials (25 +/- 13 msec) was similar to that of adjacent electrodes above the crush injury (24 +/- 11 msec), and the activation time of the late y component (89 +/- 13 msec) was similar to that of adjacent electrodes below the crush injury (91 +/- 14 msec). The timing of the x and y components was dependent on the location of the recording electrode, with x and y widely spaced at the end of the crush injury near the area of earliest atrial activation during atrial flutter, more equally timed at the center of the crush injury, and more closely timed at the end of the crush injury opposite the area of earliest activation. During transient entrainment, double potentials were accelerated to the pacing rate, but their activation time relative to adjacent electrodes was maintained. During abrupt termination of atrial flutter, the early x component of the double potential was always recorded, but the late y component was not, because of conduction block below the posterior end of the crush injury.

CONCLUSIONS
This study has shown in our canine model of atrial flutter that double potentials are recorded from the center of the reentrant circuit and that they represent sequential activations as the reentrant wave front passes on either side of the crush injury.
Prognostic determinants in hypertrophic cardiomyopathy. Prospective evaluation of a therapeutic strategy based on clinical, Holter, hemodynamic, and electrophysiological findings.
Authors: Fananapazir L , Chang A C , Epstein S E , McAreavey D 
Published: June 2012

BACKGROUND
Patients with hypertrophic cardiomyopathy (HCM) frequently have arrhythmias and hemodynamic abnormalities and are prone to sudden death and syncope. An important need exists for improved risk stratification and definition of appropriate investigation and therapy.

METHODS AND RESULTS
The relation of 31 clinical, Holter, cardiac catheterization, and electrophysiological (EP) variables to subsequent cardiac events in 230 HCM patients was examined by multivariate analysis. Studies were for cardiac arrest (n = 32), syncope (n = 80), presyncope (n = 52), ventricular tachycardia (VT) on Holter (n = 36), a strong family history of sudden death (n = 9), and palpitations (n = 21). Nonsustained VT on Holter was present in 115 patients (50%). Sustained ventricular arrhythmia was induced in 82 patients (36%). Seventeen cardiac events (eight sudden deaths, one cardiac arrest, and eight syncope with defibrillator discharges) occurred during a follow-up of 28 +/- 19 months. The 1-year and 5-year event-free rates were 99% and 79%, respectively. Two variables were significant independent predictors of subsequent events: sustained ventricular arrhythmia induced at EP study (beta, 3.5; p = 0.002) and a history of cardiac arrest or syncope (beta, 2.9; p less than 0.05). Only two of 66 patients without symptoms of impaired consciousness had a cardiac event (3-year event-free rate, 97%). In contrast, nonsustained VT on Holter was associated with a worse prognosis only in patients with symptoms of impaired consciousness: 11 of 79 symptomatic patients with VT on Holter (14%) had events versus only four of 85 symptomatic patients without VT on Holter (5%) (p = 0.057). Notably, none of 51 patients without symptoms of impaired consciousness in whom VT was not induced at EP study had a cardiac event.

CONCLUSIONS
In HCM, VT on Holter is of benign prognostic significance in the absence of symptoms of impaired consciousness and inducible VT, and sustained VT induced at EP study, especially when associated with cardiac arrest or syncope, identifies a subgroup at high risk for subsequent cardiac events.
Declining incidence of ventricular fibrillation in myocardial infarction. Implications for the prophylactic use of lidocaine.
Authors: Antman E M , Berlin J A 
Published: June 2012

BACKGROUND
The purposes of the present investigation were 1) to track the incidence of primary ventricular fibrillation (VF) in the control and lidocaine-treated groups in the randomized control trials (RCTs) of lidocaine prophylaxis against primary VF in acute myocardial infarction, with particular emphasis on the time frame of the randomized trial, and 2) to estimate the number of patients who must receive lidocaine currently to prevent one episode of VF.

METHODS AND RESULTS
The following variables from RCTs published between 1969 and 1988 were entered into logistic regression models to predict the percent of patients developing VF: year of publication of the RCT, method of data analysis used in the RCT, route and technique of lidocaine administration, duration of monitoring for VF, and exclusion criteria before randomization (congestive heart failure/cardiogenic shock, ventricular tachycardia/VF, or bradycardia/atrioventricular block). Year of publication was a significant predictor of VF in both the control and lidocaine groups (p less than or equal to 0.002) even after adjusting for other covariates. Based on a univariate logistic regression model with year as the predictor variable, it was estimated that the incidence of primary VF in the control group fell from 4.51% in 1970 to 0.35% in 1990 and from 4.32% down to 0.11% for the lidocaine group over the same time period. Thus, about 400 patients would currently need prophylaxis with lidocaine to prevent one episode of VF.

CONCLUSIONS
Present estimates of the risk:benefit ratio of lidocaine prophylaxis should consider the low risk of VF in control patients and the large number who need lidocaine prophylaxis to prevent one episode of VF. When added to the previously reported trend toward excess mortality in lidocaine-treated patients, these data argue against the routine prophylactic use of lidocaine in patients with acute myocardial infarction.
Efficacy of intravenous magnesium in acute myocardial infarction in reducing arrhythmias and mortality. Meta-analysis of magnesium in acute myocardial infarction.
Authors: Horner S M 
Published: June 2012

BACKGROUND
To ascertain the effect of the intravenous administration of magnesium in acute myocardial infarction on the frequency of arrhythmias and mortality, a meta-analysis of randomized controlled trials was performed.

METHODS AND RESULTS
The study included 930 patients with acute myocardial infarction admitted to primary referral hospitals. Administration of magnesium in acute myocardial infarction was associated with a 49% reduction in ventricular tachycardia and fibrillation. The incidence of cardiac arrest was reduced by 58%. The frequency of supraventricular tachycardias was also lower. Overall, there was a 54% reduction in mortality.

CONCLUSIONS
Intravenous magnesium is a safe and effective method of reducing the frequency of arrhythmias and mortality in acute myocardial infarction.
Influence of dietary fat, apolipoprotein E phenotype, and sex on plasma lipoprotein levels.
Authors: Cobb M M , Teitlebaum H , Risch N , Jekel J , Ostfeld A 
Published: June 2012

BACKGROUND
The "Western" diet, sex, and apolipoprotein (Apo) E polymorphism have been implicated as codeterminants of lipid levels.

METHODS AND RESULTS
In a retrospective analysis, we evaluated the combined impact of dietary fat, sex, and Apo E phenotype on lipoprotein levels in 67 subjects fed two contrasting, metabolically controlled diets: one a "Western" diet, with a low polyunsaturated to saturated (P:S) fatty acid ratio and the other a "therapeutic" diet, with a high P:S ratio. The high P:S diet compared with P:S diet exerted a far stronger predictive influence on lipoprotein concentrations than Apo E phenotype, sex, or the latter two factors combined. Apo E phenotype alone was associated with a stepwise increase in low density lipoprotein cholesterol (LDL-C), such that 3/2 less than 3/3 less than 4/3 on either the low or the high P:S diets. On the low P:S diet only, sex was shown to be a significant predictor of high density lipoprotein cholesterol (HDL-C) levels, with women greater than men, and the associated LDL/HDL ratio with men greater than women. On the high P:S diet, women displayed a dramatic fall in HDL-C, effectively raising the LDL/HDL ratio to equivalency with men and obliterating the sex influence seen with the low P:S diet. Controlled for dietary fat, Apo E and sex exerted independent, additive effects on lipoprotein levels on the low P:S diet only. Only the Apo E phenotype remained predictive on the high P:S diet.

CONCLUSIONS
Women of the Apo E 3/2 phenotype stand to benefit the least from a high P:S diet because of reduction in the more "protective" HDL-C, whereas men of the 4/3 phenotype showed the greatest improvement in the LDL/HDL ratio.
Lipoprotein lipids in older people. Results from the Cardiovascular Health Study. The CHS Collaborative Research Group.
Authors: Ettinger W H , Wahl P W , Kuller L H , Bush T L , Tracy R P , Manolio T A , Borhani N O , Wong N D , O'Leary D H 
Published: June 2012

BACKGROUND
Cardiovascular disease is the leading cause of death and disability in older people. There is little information about the distributions of risk factors in older populations. This article describes the distribution and correlates of lipoprotein lipids in people greater than or equal to 65 years old.

METHODS AND RESULTS
Lipoprotein lipid concentrations were measured in 2,106 men (M) and 2,732 women (F) who were participants in the Cardiovascular Health Study, a population-based epidemiological study. Distributions of lipids by age and sex and bivariate and multivariate relations among lipids and other variables were determined in cross-sectional analyses. Mean concentrations of lipids were cholesterol: M, 5.20 +/- 0.93 mmol/l (201 +/- 36 mg/dl) and F, 5.81 +/- 0.98 mmol/l (225 +/- 38 mg/dl); triglyceride (TG): M, 1.58 +/- 0.85 mmol/l (140 +/- 75 mg/dl) and F, 1.57 +/- 0.78 mmol/l (139 +/- 69 mg/dl); high density lipoprotein cholesterol (HDL-C): M, 1.23 +/- 0.33 mmol/l (48 +/- 16 mg/dl), and F, 1.53 +/- 0.41 mmol/l (59 +/- 16 mg/dl); low density lipoprotein cholesterol (LDL-C): M, 3.27 +/- 0.85 mmol/l (127 +/- 33 mg/dl) and F, 3.57 +/- 0.93 mmol/l (138 +/- 36 mg/dl). The total cholesterol to HDL-C ratios were M, 4.49 +/- 1.29 and F, 4.05 +/- 1.22. TG, total cholesterol, and LDL-C concentrations were lower with increasing age, the last more evident in men than in women. TG concentration was positively associated with obesity (in women), central fat patterning, glucose intolerance, use of beta-blockers (in men), and use of estrogens (in women) and negatively associated with age, renal function, alcohol use, and socioeconomic status. In general, HDL-C had opposite relations with these variables, except that estrogen use was associated with higher HDL-C concentrations. LDL-C concentration was associated with far fewer variables than the other lipids but was negatively associated with age in men and women and positively correlated with obesity and central fat patterning and negatively correlated with renal function and estrogen use in women. There were no differences in total cholesterol and LDL-C concentrations among participants with and without prevalent coronary heart disease and stroke, but TG concentration was higher and HDL-C lower in men with both coronary heart disease and stroke and in women with coronary heart disease.

CONCLUSIONS
Cholesterol and cholesterol/HDL-C ratio were lower and HDL-C higher than previously reported values in older people, suggesting that lipid risk profiles may be improving in older Americans. TG and HDL-C concentrations, and to a lesser extent LDL-C, were associated with potentially important modifiable factors such as obesity, glucose intolerance, renal function, and medication use.