The prevalence of valvular regurgitation in children with structurally normal hearts: A color Doppler echocardiographic study

The prevalence of valvular regurgitation children with structurally normal hearts: Doppler echocardiographic study

in A color

To determine the prevalence of valvular regurgitation in children (from birth to 14 years old) with structurally normal hearts, the records of 1360 consecutive patients referred for echocardiographic and Doppler examination were analyzed. A total of 461 (33.9%) patients were found to have structurally normal hearts. Flow patterns across the four valves were examined by pulsed, continuous-wave, and color Doppler imaging techniques. Regurgitation was detected in 124 (26.9%). Pulmonic regurgitation was most commonly found and was detected in 101 (21.9%) patients, tricuspid regurgitation in 29 (6.3%), and mitral regurgitation in 11 (2.4%). Aortic regurgitation was not found. Regurgitation of one valve occurred in 106 (23.0%) patients and of two valves in 16 (3.9%) patients. No patient had regurgitation of more than two valves. The prevalence of pulmonic regurgitation increased significantly with age (P < O.OOOl), whereas the prevalence of mitral, tricuspid, and bivalvular regurgitation did not change with age. Valvular regurgitation was trivial or mild in 67% of patients. Thus mild valvular regurgitation is commonly found in children with structurally normal hearts. (AM HEART J 1992;123:177.)

Abraham

Brand,

MD, Shaul Dollberg,

MD, and Andre

Doppler echocardiography is a noninvasive, sensitive, and specific tool for the diagnosis of cardiac valvular regurgitation. 1-22The addition of color Doppler flow imaging helps in mapping the regurgitant flow and enables localization of the pulse and continuouswave Doppler probes at the site of regurgitation.12, l3 The prevalence of valvular regurgitation determined by echocardiography has been reported mostly in populations of normal adults.14-17 These reports show an increase in the prevalence of valvular regurgitation mainly in the sixth decade of life.15 To determine the prevalence of valvular regurgitation in children with structurally normal hearts, we studied retrospectively the records of patients referred for twodimensional, color-coded, pulsed-wave, and continuous-wave Doppler echocardiographic examination. METHODS

The records of consecutive pediatric patients (from birth to 14 years of age) who underwent combined two-dimen-

From tal.

the Departments

Received Reprint Cholim 411133609

for publication requests: Hospital,

of Pediatrics March

and 4, 1991;

Abraham Brand, MD, PO Box 492, Jerusalem

Cardiology, accepted

Bikur July

Cholim

Hospi-

15, 1991.

Department of Pediatrics, 91004, Israel.

Bikur

Keren,

MD. Jerusalem,

Israel

sional and Doppler echocardiographic evaluation at the Division of Pediatric Cardiology, Bikur Cholim Hospital, between August 1988 and February 1990, were examined. Echocardiographic evaluation was requested because of a heart murmur in 89.2%, loss of consciousness in 4.6%) palpitation or shortness of breath in 2.6%) and chest pain in 2.2% and for other reasons in 1.4% of patients. No patient had a murmur louder than grade 2/6. Of 1360 patients evaluated, 461 (33.9%, 270 boys and 191 girls) had no echocardiographic evidence of a structural heart defect. The definition of a structurally normal heart included normal anatomy of the atria, ventricles, and great vessels with no evidence of cavity dilatation or hypertrophy, normal valves with no thickening, stenosis or calcification, normalappearing pericardium, and normal myocardial function. These 461 records comprised the study population. Initially, while the significance of mild valvular regurgitation was unclear to us, patients with mitral regurgitation and those with double-valve regurgitation underwent echocardiography more than once. Only the first study from each patient was included when repeated studies were performed. Echocardiographic examinations were performed with an Aloka SSD 860 (Aloka Co., Ltd., Tokyo, Japan) with a 3.5 or 5 MHz medium or short focus transducer. All tests included detailed M-mode and two-dimensional echocardiographic examination of the heart and great vessels. Flow patterns across the four valves were examined by pulsed, continuous-wave, and color Doppler imaging. The pulse repetition frequencies were started with 4 KHz and in-

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and Keren

American

Prevalence

of Pulmonlc

January 1992 Heart Journal

Regurgltatlon

5os%

O-1112

l/12-2

3-5

6-8

s-11

12-14

No of Pts 12

124

114

80

61

70

1. Prevalenceof pulmonic regurgitation stratified accordingto age.Prevalenceincreasedsignificantly with age (p < 0.0001).Number of children with normal hearts evaluated for presenceof pulmonic regurgitation is indicated for each age group. Fig.

creasedto 6 KHz. Low-velocity filters were set at 800 Hz for pulsed-wave and 800 to 1300Hz for continuous-wave Doppler studies. Scanning rate was 15 to 30 frames/set. Pulsed-wavesamplingvolume size was2 mm and the focus was automatic. Color Doppler variations in velocity were representedby seven groups of brightness and color intensity. Flow directed toward the transducer was conventionally coded in red and flow away from the transducer in blue. Valvular regurgitation was diagnosedwhen high-velocity turbulent Doppler signalsby either pulsedor continuous waveswere found proximal to the valve plane during its closure and extended into the chamber proximal to the valve. Regurgitation in any of the valves wasjudged when the duration of the flow signalwasmore than 100msecand the velocity exceeded1.2 m/set. Color-codedDoppler imagingwasperformed in all instancesto verify and quantify the regurgitant signalsand to direct the pulsedand continuous-wave Doppler beam. For the detection of aortic and pulmonic incompetence, the samplevolume was placed in the outflow tract of the ventricles. The parasternal short-axis view at the aortic level was used to demonstrate the pulmonic valve. The apical long-axis and apical five-chamber views were usedto demonstrate the aortic valve. The apical four-chamber view was used for visualization of the atrioventricular valves.13-‘5 Aortic regurgitation was defined astrivial when signals were obtained just proximal to the valve. Mild regurgitation was diagnosedwhen signalswere located in the left ventricular outflow tract up to the tip of the mitral valve. Signals detected from the tip of the mitral valve to the papillary musclewere consideredmoderate regurgitation. Severe regurgitation was defined as the presenceof flow beyond that point.15 Pulmonic regurgitation wasdiagnosedas trivial or mild

when retrograde signalswere located 1.5 cm or lessin the right ventricular outflow tract. Significant regurgitation was defined when flow velocities were detected 1.5 cm or more proximal to the pulmonic valve in the right ventricle.15 To estimate the severity of the atrioventricular valvular regurgitation, both atria were divided into four equal segments. Regurgitation was defined astrivial when the flow jet wasseenjust below the valve leaflets.Mild regurgitation wasdiagnosedwhen the flow was recorded in the proximal half of the atrium. Regurgitant flow wasconsideredmoderate or severe when the jet reached the third or distal fourth of the atrium, respectively.ls Statistical analysis. The chi-square test was used to comparethe prevalence of valvular regurgitation in different pediatric age groups. RESULTS

The two-dimensional echocardiographic records of 461 patients with structurally normal hearts formulated the denominator of the following results. Evidence of regurgitation of one or more valves was detected in 124 patients (26.9 % , 88 boys and 36 girls). Pulmonic regurgitation was found in 101 patients (21.9 % ,71 boys and 30 girls), tricuspid regurgitation in 29 (6.3%) 21 boys and eight girls), and mitral regurgitation in 11 (2.4 % , four boys and seven girls). Aortic regurgitation was not documented in this group. Regurgitation of one valve occurred in 106 patients (23.0%) 75 boys and 31 girls). Regurgitation of two valves occurred in 18 patients (3.9%) 13 boys and five girls). No patient had regurgitation of more than two valves. Combined regurgitation of the pulmonic and tricuspid valves was detected in 13 patients (2.8%) 10

Volume

123

Number

1

boys and three girls) followed by a combination of pulmonic and mitral valve regurgitation in three patients (0.9%) two boys and one girl). Combined regurgitation of the mitral and tricuspid valves occurred in one female patient only. The prevalence of pulmonic regurgitation increased from birth to the age of 9 years (p < 0.0001) (Fig. 1). The prevalence of mitral and tricuspid regurgitation did not vary significantly with age. The prevalence of double-valve regurgitation also increased with age: all patients were 2 years of age or more with a peak at 7 to 9 years (statistically nonsignificant). The degree of regurgitation was trivial or mild in 87% of patients (Table I). DISCUSSION

Most previous studies of valvular regurgitation in structurally normal hearts have been limited to adults.14* I5317,lg In two reportsi la the pediatric age group was included without additional detailed age stratification. The stratification of valvular regurgitation by age in a large group of pediatric patients, from birth to 14 years of age, enabled us to assess the changes that occur during childhood. The results showed a high prevalence of trivial or mild pulmonic regurgitation (21.9%). Less common was regurgitation of the tricuspid (6.3%) and mitral (2.4 % ) valves. Aortic regurgitation was not found in this group of patients. There was a significant correlation between age and pulmonic regurgitation, from none under the age of 1 year (except for newborn infants) to a peak of 42% at the age of 6 to 11 years. In most infants regurgitant flow was not detected despite excellent penetration, suggesting true absence of valvular regurgitation in this age group. The prevalence of right-sided regurgitation in newborn infants was 5.7 “0, but it tended to disappear within a few days after birth, probably because of the decrease in pulmonary pressure. In adults a decrease with age in the prevalence of pulmonic regurgitation was reported by Yoshida et a1.,13probably because of the decreased penetration of the echocardiographic signals. The correlation with age suggests an acquired rather than a congenital cause for the valvular incompetence, but the mechanism of acquired regurgitation has not been established. Physiologic pressure gradients across the valves increase with age and may cause minor damage to the valvular leaflets, which cannot be detected by current echocardiographic equipment. The low prevalence of mitral valve regurgitation and the absence of aortic regurgitation in the present series seems to indicate better preservation of left-

Valvukzr regurgitation

1. Severity of incompetent normal hearts

Table

Incompetent valve Pulmonic (72= 101) Tricuspid (n = 29) Mitral (n = 11) n, Number

in normal

children

179

valves in children with

Trivial (%)

Mild (%I

2 (2)

85 GW

4 (14) 6 (55)

21 (72) 4 (36)

Mild-moderate (%I 14 (14) 4 (14) 1 (9)

of patients.

sided valvular integrity and competence during childhood. These results suggest that in children leftsided regurgitation, especially of the aortic valve, should be considered a pathologic condition until proved otherwise, and a possible cause for the valvular incompetence should be carefully sought. Color Doppler imaging, combined with continuous- and pulsed-wave echocardiography for evaluation of valvular regurgitation in normal subjects, has been reported in one previous study.i3 This method is superior to pulsed- or continuous-wave Doppler imaging alone and enables more accurate and comprehensive detection of flow patterns. The higher sensitivity of this method accounts perhaps for the higher prevalence of valvular regurgitation found in the present study (30.3 % ) as compared with a previous study (11%) that included a group of children.i8 There was good concordance among the three types of Doppler imaging: color, pulsed, and continuouswave. In children, however, color Doppler imaging is the method of choice for diagnosis of valvular regurgitation. In insignificant or mild degrees of regurgitation, pulsed and continuous-wave Doppler techniques do not contribute significantly to the diagnosis and are time consuming. There is considerable variation in the prevalence of valvular regurgitation in normal subjects (0% to 92 % ), as reported in previous studies in which small numbers of patients were evaluated.13-17, I9 Different criteria for the diagnosis of valvular regurgitation probably account for these variations. We agree with Choong et al. la that holosystolic or holodiastolic signals are not required for the diagnosis of mild regurgitation. Small regurgitant jets probably have no hemodynamic significance. However, in some patients they may reflect subtle pathologic conditions. Longterm follow-up studies are required to prove whether this mild regurgitant flow remains unchanged and insignificant or increases with age. Limitations. The population of this study included patients who were referred for echocardiographic evaluation, mainly because of a heart murmur. None of them had systemic disease that could induce valvular regurgitation. Nevertheless, this is a selected

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population and may not reflect the true prevalence of valvular regurgitation in the normal pediatric population. Conclusions. Valvular regurgitation occurs commonly in children with structurally normal hearts referred for echocardiographic examination. Pulmanic regurgitation was the most frequently detected, followed by tricuspid and mitral regurgitation. No aortic regurgitation was found. Single-valve involvement with mild and hemodynamically insignificant flow was usually found. The prevalence of pulmonic regurgitation increased with age from none during the first year of life. These findings suggest that most types of regurgitant flow are insignificant normal variants resulting from an unknown process. The question of whether the degree of regurgitation increases with age in the same person requires longitudinal follow-up studies. One should always keep in mind that Doppler echocardiography is highly sensitive and may detect clinically insignificant physiologic valvular regurgitation. It is important to emphasize these findings to avoid “iatrogenic heart disease.” REFERENCES

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