Validation of the proximal isovelocity surface area method for assessing mitral regurgitation in children.

The proximal isovelocity surface area (PISA) method for calculating volume flow through the regurgitant orifice has attracted significant attention. A number of in vitro studies and clinical studies in adults suggest that the method is accurate. However, when applying the method to children it must be noted that the absolute regurgitation volume is small, and the range of body sizes is wide. This study investigated the accuracy of the PISA method for quantitative assessment of the severity of mitral regurgitation in children. Twenty children aged 7 months to 12 years (average 4.7 years) with mitral regurgitation but without interventricular shunt or aortic stenosis were selected for this study. Underlying cardiac diseases included atrioventricular septal defects in nine, isolated mitral regurgitation in five, and association with other heart defects in six. The PISA radius (r) and the duration of regurgitation (T) were measured on color M-mode recordings, with the M line passing through the center of the PISA. Assuming that the PISA is a hemisphere, maximal regurgitant flow rate (MFR: ml/s) was calculated as MFR = 2pi x r2 x V (r = maximal radius, V = aliasing velocity), and regurgitant stroke volume (RSVpisa) as RSVpisa = 2pi x MSR x V x T (MSR = mean square of the PISA radius during regurgitation). As a validating standard, total stroke volume (TSV) using two-dimensional echocardiography determined by the area-length volumetry method and forward stroke volume (FSV) by the pulsed Doppler method were measured, and regurgitant stroke volume (RSVD: RSVD = TSV - FSV) and regurgitant fraction (RF: RF = RSVD/TSV) were calculated. A linear correlation was found between MFR, RSVpisa, and RSVD (X) (MFR = 4.2X + 54.0, r = 0.84. RSVpisa = 1. 0X + 9.8, r = 0.90), and both RSVpisa and MFR divided by body surface area (BSA: m2) revealed a significant correlation with regurgitant fraction (X) by nonlinear regression analysis (RSVpisa/BSA = 26.2 x X/(1 - X) + 16.8, r = 0.85. MFR/BSA = 121.8 x X/(1 - X) + 92.2, r = 0.79). It is concluded that maximal regurgitant flow rate, regurgitant stroke volume, and regurgitant fraction can be accurately predicted in children using the PISA method by Doppler echocardiography.

Measurement of ventricular volumes by cine magnetic resonance imaging in complex congenital heart disease with morphologically abnormal ventricles.

This study assessed the validity of cine magnetic resonance imaging (MRI) for measuring right and left ventricular volumes by using Simpson's rule in children with complex congenital heart disease. Forty-five patients with complex congenital heart disease (average age 2.6 years) and 10 controls (average age 2.3 years) were evaluated. The whole heart was encompassed by contiguous transverse sections. Ventricular volumes were calculated by adding luminal areas determined in each section at end diastole and end systole. End-diastolic and end-systolic volumes by MRI in both groups correlated well with those by ventriculography (r>0.89). Comparison of the ejection fraction in both ventricles in both groups yielded a good correlation between MRI and ventriculography (r>0.67). MRI technique in both groups had low intraobserver and interobserver variation (<6%). Cine MRI provides a suitable noninvasive means of quantifying ventricular volume in children with complex congenital heart disease.

Thrombocytopenia: a risk factor for acute myocardial infarction during the acute phase of Kawasaki disease.

BACKGROUND: We report on 10 patients with Kawasaki disease and thrombocytopenia who were found to have a high incidence of coronary artery aneurysm and acute myocardial infarction. The clinical features of these patients, the cause of their thrombocytopenia and the relationship between cardiovascular pathology and thrombocytopenia were analyzed. METHODS: The clinical features of 10 patients with Kawasaki disease found to have thrombocytopenia (group A: mean age 8.0 +/- 7.0 months) and those of 293 patients with Kawasaki disease (group B, controls: mean age 13 +/- 20 months) were analyzed. Coagulation studies and bone marrow aspiration were performed to ascertain the cause of the thrombocytopenia in nine out of 10 subjects in group A. RESULTS: The minimum platelet count was 4-12 x 10(4)/mm3 (average day of illness, 10.3) and platelet counts were elevated to the baseline value within 1-2 weeks of onset of the illness. Low fibrinogen concentrations, high levels of fibrin degradation products, and low erythrocyte sedimentation rates with high C-reactive protein levels were observed in seven patients. In two other patients, immature megakaryocytes with normal coagulation values were observed. The differences in the incidence of coronary artery aneurysm and acute myocardial infarction between groups A and B were highly significant (coronary artery aneurysm: 60% in group A, 8.9% in group B; acute myocardial infarction: 40% in group A, 0.3% in group B). CONCLUSIONS: In many patients with Kawasaki disease and thrombocytopenia, the thrombocytopenia appears to be a result of intravascular coagulation, and to be one of the risk factors for acute myocardial infarction.

Magnetic resonance imaging of heterotaxia in infants.

OBJECTIVES: This study assessed the usefulness and safety of magnetic resonance imaging (MRI) for systematically diagnosing heterotaxia in infants. BACKGROUND: Although it is important to diagnose and treat infants with heterotaxia, which is associated with viscerobronchial cardiovascular anomalies, systematic diagnosis of these anomalies by a single imaging technique is difficult. METHODS: Twenty patients with heterotaxia were evaluated. The infants ranged in age from 21 days to 12 months (average 5.2 months, average body weight 4.3 kg). Electrocardiographically gated MRI was performed by spin echo imaging techniques operating at 0.5 tesla. RESULTS: In all 20 patients, MRI results were sufficient to evaluate these anomalies without serious complications. In 17 patients, neither a spleen nor splenules were detected, but in 3 patients, a polymorphous spleen was visualized. In all 20 patients, bronchial anatomies were clearly visualized (bilateral eparterial bronchi in 14 patients, bilateral hyparterial bronchi in 2 and normal bronchial patterns in 4). Additionally, in a comparison of 149 observations of cardiovascular anatomy by MRI with those by angiography, discrepancies were found in only 10 observations (6.7%). CONCLUSIONS: Magnetic resonance imaging was found to be safe and very useful for the systematic diagnosis of heterotaxia in infants.