The difficulties in assessing right ventricular function

SERCA-2a is involved in the right ventricular function following myocardial infarction in rats

AIMS

Right ventricular (RV) function is considered an independent predictor of mortality and development of heart failure (HF) in patients with left ventricle dysfunction following myocardial infarction (MI). The functional and molecular mechanisms that may explain the RV dysfunction are still poorly understood. Our study was conducted to investigate RV contractility and the myocardium protein involved in the calcium handling following MI in rats.

MAIN METHODS

MI was surgically induced in male Wistar rats to create transmural infarctions involving 40-60% of the left ventricle surface. Infarcted rats were divided into two groups: those that presented classical signs of congestive heart failure (HF group) and those that did not (INF group), and compared to control animals (Sham). RV contractility was studied using isometric contraction in isolated strips and isovolumetric pressure in isolated heart.

KEY FINDINGS

Inotropic responses in RV strips were preserved in the INF group but were reduced in the HF group (3.75 mM Ca(2+) treatment: Sham = 163 ± 18; INF = 148 ± 19; HF = 68 ± 11 g/g*; *p < 0.05; 5 × 10(-5) M isoproterenol: Sham = 151 ± 15, INF = 134 ± 17, HF = 52 ± 7 g/g*; *p < 0.05). An increase in SERCA-2a protein expression in the RV was observed in the INF group but not in the HF group, which could explain the preserved inotropic response in these animals.

SIGNIFICANCE

Increased SERCA-2a protein expression may play a role in the preservation of RV function post-MI. Therefore, therapeutic strategies that attempt to increase SERCA protein expression levels may be useful for the treatment of HF.

Clinical asthma phenotypes: is there an impact on myocardial performance?

BACKGROUND

Asthma is a systemic disease, which affects various body systems. We aimed to assess the impact of clinical asthma phenotypes on myocardial performance in asthmatic children using tissue Doppler imaging (TDI).

METHODS

We enrolled 58 children with moderate persistent asthma and 62 age- and sex-matched healthy controls. Asthmatic children were classified according to clinical asthma phenotypes into shortness of breath group (n = 26) and wheezy group (n = 32). Pulmonary function tests, and conventional and TDI echocardiography were performed.

RESULTS

TDI echocardiography assessment of the studied groups showed that asthmatic children as a group had significant left and right ventricular dysfunction when compared with healthy controls. Children in the shortness of breath group had a significant diastolic dysfunction of both ventricles in the form of lower tricuspid and mitral annular early myocardial diastolic velocity (Em), early to late myocardial diastolic velocity (Em/Am) ratio, and prolonged isovolumetric relaxation time when compared with wheezy group (P < 0.001). In the shortness of breath group, TDI-derived myocardial performance index (MPI) of both ventricles was significantly higher when compared with wheezy group (P < 0.001) reflecting global myocardial dysfunction. Conventional echocardiography of both ventricles showed RV diastolic dysfunction in the form of a significantly lower tricuspid E/A ratio in the shortness of breath group when compared with wheezy group.

CONCLUSION

Clinical asthma phenotypes have an impact on myocardial function especially those presented with shortness of breath. Thus, measurement of MPI by TDI can detect subclinical changes in the cardiac performance in asthmatic children.

Right ventricular subclinical diastolic dysfunction in obese children: the effect of weight reduction with a low-carbohydrate diet

This study aimed primarily to identify whether childhood obesity leads to right ventricular (RV) subclinical diastolic dysfunction or not. It also aimed to examine the effect of weight reduction on right ventricular function. Standard and tissue Doppler echocardiography was performed for 28 overweight (body mass index [BMI], 25-30 kg/m(2)) and 34 obese (BMI, > or = 30 kg/m(2)) children and for 29 age- and sex-matched lean referents (BMI, 17-25 kg/m(2)). Levels of plasma lipids, fasting glucose, insulin, and homeostatic model assessment of insulin resistance (HOMA-IR) were obtained for all the participants. For 6 months, 30 obese children were given a low-carbohydrate diet and then reevaluated by echocardiography. Conventional echocardiographic parameters all were similar for obese, overweight, and lean control children. The tricuspid free-wall isovolumetric relaxation time (IVRT), tricuspid lateral annular early diastolic velocity (e'), ratio of early-to-late diastolic velocity (e'/a'), and tricuspid lateral annular IVRT differed significantly between the overweight and control children. The RV tissue Doppler parameters were found to be similar between the preobese and control children. The IVRT of the RV free wall and lateral tricuspid annulus was significantly decreased, and the e'/a' of the lateral tricuspid annulus was significantly increased after the diet. In conclusion, obesity is associated with subclinical RV diastolic dysfunction in pediatric patients. Weight reduction with a low-carbohydrate diet may reverse the effects of obesity on RV diastolic function.

Usefulness of right ventricular fractional area change to predict death, heart failure, and stroke following myocardial infarction (from the VALIANT ECHO Study)

Severe right ventricular dysfunction independent of left ventricular ejection fraction increased the risk of heart failure (HF) and death after myocardial infarction (MI). The association between right ventricular function and other clinical outcomes after MI was less clear. Two-dimensional echocardiograms were obtained in 605 patients with left ventricular dysfunction and/or clinical/radiologic evidence of HF from the VALIANT echocardiographic substudy (mean 5.0 +/- 2.5 days after MI). Clinical outcomes included all-cause mortality, cardiovascular (CV) death, sudden death, HF, and stroke. Baseline right ventricular function was measured in 522 patients using right ventricular fractional area change (RVFAC) and was related to clinical outcomes. Mean RVFAC was 41.9 +/- 4.3% (range 19.2% to 53.1%). The incidence of clinical events increased with decreasing RVFAC. After adjusting for 11 covariates, including age, ejection fraction, and Killip's classification, decreased RVFAC was independently associated with increased risk of all-cause mortality (hazard ratio [HR] 1.61, 95% confidence interval [CI] 1.31 to 1.98), CV death (HR 1.62, 95% CI 1.30 to 2.01), sudden death (HR 1.79, 95% CI 1.26 to 2.54), HF (HR 1.48, 95% CI 1.17 to 1.86), and stroke (HR 2.95, 95% CI 1.76 to 4.95), but not recurrent MI. Each 5% decrease in baseline RVFAC was associated with a 1.53 (95% CI 1.24 to 1.88) increased risk of fatal and nonfatal CV outcomes. In conclusion, decreased right ventricular systolic function is a major risk factor for death, sudden death, HF, and stroke after MI.

Tissue Doppler echocardiographic assessment of cardiac function in children with bronchial asthma

BACKGROUND

The aim of the present study was to evaluate the role of tissue Doppler echocardiography in assessment of ventricular function in pediatric patients with bronchial asthma (BA).

PATIENTS AND METHODS

Fifty-one pediatric patients with BA and 30 age- and sex-matched healthy subjects were studied. BA patients were divided into two groups: mild BA (n = 33) and moderate to severe BA (n = 18). All subjects were examined on conventional and tissue Doppler echocardiography, and 44 patients had pulmonary function tests on spirometry within 1 week of echocardiographic examination.

RESULTS

Conventional echocardiographic parameters were all similar in mild asthmatic patients and control subjects. Tricuspid E velocity, E/A ratio and isovolumetric relaxation time (IVRT) in moderate and severe cases differed significantly from mild cases and control subjects. E', A', E'/A' ratio and IVRT of the lateral tricuspid annulus, and IVRT of the medial and lateral mitral annuli were different between mild cases and control subjects. E' velocity and IVRT of the lateral tricuspid annulus and IVRT of the medial and lateral mitral annuli were also different between mild cases and moderate to severe cases. Pulmonary function tests correlated well with E', E'/A' and IVRT of lateral tricuspid annulus.

CONCLUSION

Patients with BA have subclinical right ventricular diastolic dysfunction even in the early stages. The severity of the functional impairment is parallel with the severity of the disease. Tissue Doppler echocardiography has a greater predictive value than conventional imaging, and is useful for evaluating ventricular function in patients with BA.