Effect of Oral H2-Receptor Antagonists on Left Ventricular Systolic Function and Exercise Capacity in Patients with Chronic Stable Heart Failure

Study Objective . To evaluate the effect of cimetidine, famotidine, ranitidine, and placebo on left ventricular systolic function, aerobic metabolic performance, and exercise capacity in patients with chronic, stable heart failure. Design . Double-blind, randomized, placebo-controlled, four-way crossover study. Setting . Outpatient, university-affiliated cardiology clinic. Patients . Twelve men with stable New York Heart Association class II or III heart failure secondary to ischemic heart disease or hypertension. Interventions . Patients received in random sequence cimetidine 400 mg twice/day, famotidine 40 mg/day, ranitidine 150 mg twice/day, and placebo. Each treatment was administered for 7 days, and the periods were separated by a 1-week washout. Measurements and Main Results . Before and after each treatment, patients underwent a bicycle stress echocardiogram with aerobic metabolic assessment. Left ventricular function was evaluated by calculating ejection phase indexes from Doppler echocardiographic measurements. All 12 patients successfully completed the study. No patient reported any adverse effect attributed to study drugs. None of the treatments was associated with significant changes in any measure of left ventricular systolic function, aerobic metabolic performance, or exercise capacity, nor were placebo-subtracted differences for the agents significantly different for any of the three measures.     

Thrombus formation after the Fontan operation

Background. Thrombus formation is common after a Fontan operation. We investigated the frequency and location of thrombus in our population of children based on the type of Fontan operation performed.

Methods and Results. Between January 1987 and January 1999, 592 patients underwent echocardiography after Fontan operation and 52 (8.8%) had intracardiac thrombus. Median age at Fontan operation was 1.9 years (range 0.8 to 35.1). Freedom from thrombus was 92%, 90%, 84% and 82% at 1, 3, 8, and 10 years after Fontan operation, respectively. There was no difference in freedom from thrombus, based on type of operation (atriopulmonary vs. lateral tunnel) or presence of fenestration. Thrombus was detected in the systemic venous atrium in 26 (48%), in the pulmonary venous atrium in 22 (44%), in both atria in 1 (2%), in the hypoplastic left ventricular cavity in 2 (8%), and in the ligated pulmonary artery stump in 1 (2%).

Conclusions. Thrombus formation occurs with equal frequency in all types of modifications and is seen in the pulmonary, as well as the systemic venous atria. Our study suggests that thrombus formation is inherent to the physiology after Fontan operation and is not related to the type of modification performed.     

Extent of myocardial viability predicts response to biventricular pacing in ischemic cardiomyopathy

BACKGROUND: The clinical response to biventricular pacing is unpredictable, especially in patients with ischemic cardiomyopathy. OBJECTIVES: The purpose of this study was to prospectively examine the relationship between the extent of myocardial viability and the response to cardiac resynchronization therapy. METHODS: Twenty-one patients with ischemic left ventricular (LV) dysfunction (left ventricular ejection fraction [LVEF] 21 +/- 5%), New York Heart Association (NYHA) functional class III-IV, and QRS >120 ms received biventricular devices. Myocardial viability was assessed by myocardial contrast echocardiography, and a perfusion score index (PSI) was calculated from summed segmental perfusion scores. LV performance was assessed by echocardiography on the day after implantation and at 6 months. RESULTS: PSI was closely correlated with acute improvement in LVEF (P = .003, r = 0.65), stroke volume (P = .02, r = 0.54), and end-systolic volume (P = .05, r = -0.49). PSI also correlated with early diastolic LV relaxation (E', P < .05, r = 0.50) and global myocardial performance or Tei index (P = .003, r = 0.63). By multiple linear regression analysis, PSI provided incremental predictive value to the degree of dyssynchrony, measured by tissue Doppler imaging, for predicting improvement in LVEF. At 6 months, PSI remained positively correlated with improvement in ventricular performance and with reduction in LV end-diastolic dimension (P = .003, r = -0.68). PSI also influenced the clinical variables of NYHA class, 6-minute walk distance, quality-of-life score, and number of hospitalizations for heart failure. CONCLUSION: In patients with ischemic cardiomyopathy, the extent of myocardial viability predicts acute and long-term improvement in LV performance, exercise tolerance, and reduction in LV end-diastolic dimension with biventricular pacing.     

Cardiac Limited Ultrasound Examination Techniques to Augment the Bedside Cardiac Physical Examination

The current practice of physical diagnosis is dependent on physician skills and biases, inductive reasoning, and time efficiency. Although the clinical utility of echocardiography is well known, few data exist on how to integrate 2‐dimensional screening “quick‐look” ultrasound applications into a novel, modernized cardiac physical examination. We discuss the evidence basis behind ultrasound “signs” pertinent to the cardiovascular system and elemental in synthesis of bedside diagnoses and propose the application of a brief cardiac limited ultrasound examination based on these signs. An ultrasound‐augmented cardiac physical examination can be taught in traditional medical education and has the potential to improve bedside diagnosis and patient care.     

Intracardiac echocardiography using the AcuNav ultrasound catheter during percutaneous balloon mitral valvuloplasty

During the past 10 years, there has been a trend toward and an interest in the use of catheter-based interventions to perform procedures that were once only approached surgically. The problem with the catheter-based approach has been procedure-related complications. Improved imaging of cardiac structures while undertaking interventional procedures may help to prevent or allow for early identification of these complications. Transesophageal echocardiography has been used during catheter-based procedures as a guide, and has both advantages and disadvantages. Intracardiac echocardiography is a relatively new imaging technique that also provides an enhanced view of cardiac structures and may also allow for the safe and efficient performance of catheter-based procedures. We report the first case of successful percutaneous balloon mitral valvuloplasty done under ultrasound guidance using an intracardiac echocardiography catheter (10F, 5-10 MHz) (Acunav). The strengths and weaknesses of this approach are described and compared with transesophageal echocardiography and older intracardiac echocardiography devices.     

Effectiveness of Prenatal Screening for Congenital Heart Disease: Assessment in a Jurisdiction With Universal Access to Health Care

Background

Neonates with certain forms of severe congenital heart disease (CHD) diagnosed prenatally might have better outcomes in comparison with those diagnosed after birth. The proportion of prenatally detected neonates with severe CHD and the effect of prenatal diagnosis on clinical outcomes have not been previously investigated in Canada.

Methods

We retrospectively studied infants in Alberta, Canada, who required surgical or catheter intervention for CHD at younger than 1 year of age, between January 2007 and December 2010, and pregnancy terminations affected by CHD.

Results

Of the 374 subjects identified (327 infants, 47 pregnancies with termination), 188 (50%) were detected prenatally. Failure of prenatal diagnosis was associated with anomalies not involving the 4-chamber view on ultrasound (odds ratio, 1.86; 95% confidence interval, 1.48-2.35; P < 0.001) and region of residence (P = 0.04). Prenatal detection was associated with fewer days to hospital admission (P < 0.001), fewer days to surgery (P = 0.003), and greater use of prostaglandins (P = 0.001). Infants diagnosed prenatally who underwent surgery within 15 days of age had higher preductal O₂ saturations (P = 0.04), fewer days to admission (P = 0.03), and less frequently required preoperative intubation (P = 0.004), and inotropes (P = 0.001). Pregnancy termination occurred among 49% of fetuses detected before 24 weeks' gestation.

Conclusions

Only 50% of fetuses and/or neonates with severe CHD managed in Alberta have a prenatal diagnosis. The likelihood of prenatal detection is influenced by the status of the 4-chamber view on ultrasound and the region of maternal residence indicating heterogeneous access to fetal echocardiography within Alberta. Prenatal detection might improve clinical outcomes for neonates with severe CHD.     

Exercise Function of Children with Congenital Aortic Stenosis Following Aortic Valvuloplasty during Early Infancy

Objectives. The objectives of this study were to characterize the exercise function of patients treated with balloon aortic valvuloplasty at ≤6 months of age, and identify factors associated with exercise dysfunction. Background. Balloon aortic valvuloplasty is the primary therapy for neonatal aortic stenosis (AS). Residual and/or acquired abnormalities of left heart structure and function may adversely affect exercise capacity. Methods. We prospectively recruited patients >6 years old with a history of neonatal AS to undergo exercise testing. Results. We enrolled 30 patients (median age 13.1 years) who underwent balloon aortic valvuloplasty at a median age of 12 days. At time of exercise testing, the median maximum Doppler AS gradient was 34 mm Hg (0–70 mm Hg); 11 patients had moderate or severe aortic regurgitation. All patients were asymptomatic. Overall, peak oxygen consumption (VO₂) was below normal (87 ± 18% predicted; P < .001), and was severely depressed (≤70% predicted) in 7 patients (23%). Although peak O₂ pulse was well preserved overall (97 ± 22% predicted; P= .36), 11 patients had an O₂ pulse <85% predicted, including all patients with VO₂≤ 70% predicted. Peak heart rate was below normal overall (91 ± 7% predicted, P < .001), but severe chronotropic dysfunction (≤70% predicted) was rare (n = 1). Age at testing correlated inversely with peak VO₂ (R²= 0.30; P= .002). No other demographic, historical, or echocardiographic variables were associated with peak VO₂. Conclusion. Although exercise function is preserved in most patients with a history of AS treated in early infancy, a subset have markedly reduced peak VO₂, usually because of inability to increase stroke volume.