Nancy Hutcheon

M-mode echocardiography in normal children and adolescents: Some new perspectives

SummaryNormal M-mode echocardiography values were determined using computer-assisted measurements of echocardiograms (echo) in 202 children and young adults 25 days to 23 years of age: 77 were female, and 125 were male and, reflecting the population served by our Center, 99 were black and 103 were white children. The values for left and right heart wall thicknesses and chamber sizes were graphically displayed as a function of body surface area, and with an illustration of the regression line and 2 standard deviation (SD) range of normal for each parameter. In addition, normalecho predicting equations for dimension and function parameters were derived using multiple linear regression analysis with age, height, weight, sex, race, and heart rate as independent variables.A comparison was made between the observed data and the data derived from the normal predicting equations for each of the parameters. Also, values obtained from these equations were compared to data generated from other published normal predicting equations. A description of the digitizer measurements, computer interfacing, and a sampleecho report form utilizing the predicted normal ranges for each of the parameters is presented. We propose that quantitative M-mode echocardiographic reporting should be easily accessible to all pediatric cardiology laboratories.

Estimation of circumferential fiber shortening velocity by echocardiography

The M-mode and two-dimensional echocardiograms of 40 young patients were analyzed to compare the mean circumferential fiber shortening velocity (Vcf) of the left ventricle calculated separately by two methods. The mean circumferential fiber shortening velocity was derived from the M-mode echocardiogram as minor axis shortening/ejection time and derived from the two-dimensional echocardiogram as actual circumference change/ejection time. With computer assistance, circumference was determined from the short-axis two-dimensional echocardiographic images during end-diastole and end-systole. Good correlations were obtained between the left ventricular diameter derived by M-mode echocardiography and the vertical axis during end-diastole (r = 0.79) and end-systole (r = 0.88) derived by two-dimensional echocardiography. Likewise, high correlations were noted between diameter and circumference in end-diastole (r = 0.89) and end-systole (r = 0.88). However, comparison of Vcf obtained by M-mode echocardiography with that obtained by two-dimensional echocardiography showed only fair correlation (r = 0.68). Moreover, the diameter/circumference ratio determined in end-diastole and end-systole differed significantly (p less than 0.001), possibly owing to the change in geometry of the ventricular sector image during systole. Although Vcf derived by M-mode echocardiography is a useful index of left ventricular performance, it does not truly reflect the circumference change during systole.

An evaluation of the left atrial/aortic root ratio in children with ventricular septal defect.

Echocardiograms were performed in 80 infants and children with isolated ventricular septal defect (VSD) who underwent cardiac catheterization. The pulmonary-to-systemic flow ratio (Qp/Qs) was correlated with the echocardiographic left atrial-to-aortic root diameter ratio (LA/Ao), and a relatively poor correlation (r = 0.62) was found.The end-systolic diameters of the left atrium and aorta at the level of the aortic root, obtained from lateral cineangiograms of 55 of the 80 patients, were compared with the corresponding echocardiographic dimensions. To assess the possible effect of transducer beam angulation upon the echocardiographic determinations, the angiographic measurements were made at 00 position (perpendicular to the frontal plane) and at angles of 50, 100, 15%deg; and 200 from zero, using the aortic root center as the point of intersection. The echocardiographic and angiographic aortic root measurements were comparable (r = 0.95), and the angiographically derived aortic diameter did not vary with different angle projections. However, the left atrial angiographic dimensions were significantly influenced by the angle of projection. We conclude that the echocardiographic LA/Ao ratio cannot reliably estimate the severity of the shunt flow in VSD.

Cardiovascular effects of hypertransfusion therapy in children with sickle cell anemia

SummaryThirteen children, age 1.9 to 14.8 years with documented sickle cell disease, underwent echocardiographic assessment of cardiac status while on and off periodic hypertransfusion therapy (HTX). Two to three units of washed packed red blood cells were transfused every 2–4 weeks in children with splenic sequestration crises, cerebrovascular accidents (CVA), aseptic necrosis of the femoral head, and miscellaneous complications of sickle cell disease to maintain hemoglobin (Hgb) concentrations of ≧10g/dl and % sickle hemoglobin (S Hgb) of ≦20%. This therapy administered over an average duration of 24 months resulted in normalization of left heart chamber enlargement and statistically significant decrease in heart rate, left ventricular mass, and cardiac output. Echocardiographically derived left ventricular function parameters remained normal on and off transfusion therapy. Changes in left ventricular diastolic dimension and cardiac output correlated with changes in % S Hgb (r=0.59,p<0.001; andr =0.54,p<0.001, respectively), and with changes in Hgb concentration (r=−0.78,r=−0.76,p<0.001). Expression of left heart abnormalities as a single composite function (Ydv), using multivariate regression analysis, allowed a comparison of cardiac status of 99 normal black controls, nontransfused sickle cell anemia (SCA) patients, and 13 study patients on and off HTX, and permitted serial assessment of cardiac status on and off treatment over 5 years in a single patient. Normalization of left heart abnormalities in children with sickle cell disease receiving HTX provides further evidence that the major cardiac changes are due to the hypervolemia that results from chronic anemia, and that these changes are reversible with correction of the anemia. Although the specific effect of iron-overload from chronic transfusion therapy was not assessed, we did not find evidence for myocardial dysfunction in children with SCA on or off HTX.

Cardiac abnormalities in children with hyperthyroidism

SummaryThe cardiac status of 18 hyperthyroid (HT) children (9 black and 9 white) was evaluated by echocardiography. Mitral regurgitation (MR) was diagnosed clinically in 33% (6 of the 9 blacks). None of the 9 white children had MR. Left ventricular end-diastolic diameter (LVEDD) and volume (LVEDV) did not differ from the predicted normal (PN) based on body surface area and heart rate, except in those with MR where increased LVEDD and LVEDV were noted (p<0.02). LV mass was +1.75 standard deviations (σ) of the PN (p<0.01), due to increased wall thickness or LVEDV. Left ventricular output (LVO) was +0.35σ PN (p=ns); however, when compared to that of normal children, LVO of HT was higher (p<0.001) due to the increased heart rate. Enhanced left ventricular contractility was suggested by increased rate of dimensional change during ejection (peak dD/dt-syst), with a mean value of −11.39 cm/sec as compared to the normal of −9.54 cm/sec (p<0.01). A linear multivariate regression equation differentiated the cardiac status of HT from that of normal children. Following treatment to euthyroid state, MR disappeared in 2 and became less in 4 patients. LVO, LV mass, and peak dD/dt-syst also became less. Significant cardiac changes occur in children with hyperthyroidism, which may be reversible in part after euthyroidism is restored.

185 ASYMPTOMATIC CARDIOMYOPATHY IN SYSTEMIC LUPUS ERYTHEMATOSUS (SLE)

Twelve adolescents with SLE were studied by M-mode echocardiography. All patients had received prednisone for the duration of their illness (1 mo-7 yrs). None had symptomatic heart disease although the following were present: cardiomegaly by x-ray (4 pts), hypertension (8 pts), nonspecific ECG changes (5 pts). Pericardial effusion was present in 6 patients. Left ventricular (LV) end diastolic dimension, percent minor axis shortening and the ratio of pre-ejection period to ejection time were normal. Posterior wall thickness (p < .001), calculated LV mass (p < .05) and LV mass/volume (p < .025) were abnormal but not related (linear regression) to blood pressure. Maximum rates of continuous LV dimension change (dD/dt) were normal. However, the time from electrocardiographic Q-wave to minimum and maximum dD/dt (p < .025) and Q-wave to mitral valve opening (p < .05), corrected for heart rate, were abnormal. These data suggest that clinically unsuspected cardiomyopathy is associated with SLE and that it is not defined by the usually measured M-mode echocardiographic parameters.

132 CARDIAC EFFECTS OF HYPERTRANSFUSION THERAPY IN SICKLE CELL DISEASE (SS)

Serial echocardiography was used to assess cardiac size and function of 5 children (0. 9 to 16 years) on hypertransfusion therapy (HT) for clinical problems related to SS. Satisfactory HT status, defined as total Hb levels maintained at ≥10 gm% and Hb-S at <10%, was achieved with washed packed RBC transfusion every 2-3 weeks. Iron status was monitored. Echo measurements of LV dimension (LVD), LA dimension (LAD), LV wall thickness (W), LV mass (M), cardiac output (Q), PEP/ET ratio and circumferential fiber shortening velocity (VCF) were obtained every 2-4 months during HT. These were compared to those of 100 normal children (48 Blacks, 52 Whites). Clinical improvement was dramatic. In one child (age 1 yr), the echo data remained normal before and during HT. The values in the other 4, expressed as % of predicted normal, before (C) and during HT for 8-10 mos are as follows:The improved clinical status during HT is accompanied by diminution of cardiac size and of the high-output state. These changes may reverse after HT is discontinued.

131 ECHO EVALUATION OF CARDIAC STATUS IN HOMOZYGOUS SICKLE CELL DISEASE (SS)

Cardiac size and function were evaluated in 47 clinically-well non-hypertransfused children with SS, age 0. 6 to 19 years, using echocardiography. Steady-state hemoglobin ranged from 5. 5 to 10. 0 gm%; in 29, ≥7 gm% (gp A) and in 16, <7 gm% (gp B). Age-matched normal children (48 Blacks, 52 Whites) were controls (N). Echo parameters included: RV dimension (RVD), LA dimension (LAD), LV dimension (LVD), LV wall thickness (W), LV mass (M), cardiac output (Q), and LV function parameters including circumferential fiber shortening velocity (VCF) and LV pre-ejection/ejection time ratio (PEP/ET). The 1n of BSA was plotted against In echo parameters except in VCF where In heart rate was used. Data were expressed in percent of predicted normal. Increased values (>2 SD from N mean) were observed for RVD (in 22%), LAD (in 54%), LVD (in 52%), W (in 28%), M (in 61%), Q (in 50%), VCF (in 7%) and PEP/ET (in 34%). Group t-tests vs N showed significant differences (p<0. 001) except for VCF. Gp B had greater LVD, M, and LAD than gp A (p<0.01 to <0.05). The degree of abnormality did not correlate with age. Children with SS have cardiac volume overload and a compensated high-output state. The abnormal LV wall and PEP/ET seen in certain patients may suggest secondary myocardial disease.