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Heart Murmurs

Ninety percent of children will have an audible heart murmur at some point in time. Normal murmurs include vibratory and pulmonary flow murmurs, venous hums, carotid bruits, and the murmur of physiologic branch pulmonary artery stenosis. Less than 5% of heart murmurs in children are caused by cardiac pathology.

Clinical Evaluation of Heart Murmurs

Cyanosis, exercise intolerance, feeding difficulties, dyspnea, or syncope signify potential cardiac dysfunction. Failure to thrive, diffuse diaphoresis, unexplained persistent irritability or lethargy, and atypical chest pain also suggest the possibility of organic heart disease.

The majority of children who have heart murmurs are asymptomatic. In early infancy, however, cardiac malformations that are critical may manifest as persistent peaceful tachypnea (a respiratory rate greater than 60 breaths/min).

Syndromes and Associated Cardiac Malformations

Syndrome

Incidence of Cardiac Malformations (%)

Cardiac Malformations

Down Syndrome

50

AVSD, VSD, ASD, PDA, TOF

Trisomy 18

99

VSD, PDA, DORV, BPV

Trisomy 13

90

VSD, ASD, PDA

Turner Syndrome

40

Aortic coarctation, AVS, HLH

Noonan Syndrome

50

PVS, HCM

William Syndrome

90

SVAS, SVPS, RAS

Marfan Syndrome

60-80

MVP, AoRD, AI

DiGeorge Syndrome

90

IAA (B), TA

VACTERL

80

VSD, ASD, PDA, TOF

AVSD = atrioventricular septal or canal defect, VSD = ventricular septal defect, ASD = atrial septal defect, PDA = patent ductus arteriosus, TOF = tetralogy of Fallot, DORV = double outlet right ventricle, BPV = bicuspid pulmonary valve, AVS = aortic valve stenosis, HLH = hypoplastic left heart, PVS = pulmonary valve stenosis, HCM = hypertrophic cardiomyopathy, SVAS = supravalvular aortic stenosis, SVPS = supravalvular pulmonary stenosis, RAS = renal artery stenosis, MVP = mitral valve prolapse, AoRD = aortic root dilatation, AI = aortic insufficiency, IAA (B) = interrupted

Family history of a congenital cardiovascular malformation increases the risk of a cardiac defect, such as with DiGeorge syndrome (type B interrupted aortic arch, truncus arteriosus).

Gestational course should be reviewed for exposure to teratogens or maternal illnesses. Fetal exposure to lithium may cause Ebstein anomaly of the tricuspid valve. Ventricular and atrial septal defects occur with fetal alcohol syndrome. Transient hypertrophic cardiomyopathy and tetralogy of Fallot are associated with infants of diabetic mothers. Maternal collagen vascular disease may lead to the development of fetal complete heart block.

Physical Examination

Noncardiac malformations. Twenty five percent of children who have heart disease have extracardiac anomalies.

Major gastrointestinal malformations (diaphragmatic hernia, tracheoesophageal fistula and esophageal atresia, omphalocele, imperforate anus) are associated with congenital cardiac defects in 15-25% of infants. The most common cardiac malformations are ventricular septal defect and tetralogy of Fallot.

Cyanotic infants or children should be immediately referred to a cardiologist. Abnormal rate or pattern of breathing, a persistently hyperdynamic precordium, precordial bulging, or asymmetric pulses should also be referred.

Signs of congestive heart failure (inappropriate tachycardia, tachypnea, hepatomegaly, abnormal pulse volume) also should prompt a referral to a cardiologist.

Auscultatory Criteria Signifying Cardiac Disease

Loud, pansystolic, late systolic, diastolic, or continuous murmurs; an abnormally loud or single second heart sound

Fourth heart sound or S4 gallop

Ejection or midsystolic clicks

Characteristics of Organic Murmurs

Lesion

Shape

Timing

Location

Other Findings

Ventricular septal defect (VSD)

Plateau

Holosystolic

LLSB

Apical mid- diastolic murmur

Mitral regurgitation

Plateau

Holosystolic

Apex

Higher pitched than VSD murmur

Atrial septal defect

Ejection

Systolic

ULSB

Persistent S2 split

Patent ductus arteriosus

Diamond

Continuous

ULSB

Bounding pulses

Aortic valve stenosis

Ejection

Systolic

URSB

Ejection click

Subvalvular aortic stenosis

Ejection

Systolic

ML-URSB

No ejection click

Hypertrophic cardiomyopathy

Ejection

Systolic

LLSB- apex

Laterally displaced PMI

Coarctation

Ejection

Systolic

ULSB-Left back

Pulse disparity

Pulmonary valve stenosis

Ejection

Systolic

ULSB

Ejection click; wide S2 split

Tetralogy of Fallot

Ejection

Systolic

MLSB

Cyanosis

LLSB = lower left sternal border, ULSB = upper left sternal border, URSB = upper right sternal border, MLSB = mid-left sternal border, S2 = second heart sound, PMI = point of maximal impulse.

Ventricular septal defect (VSD) is a harsh pansystolic murmur of even amplitude that is audible at the lower left sternal border.

Patent ductus arteriosus (PDA) causes a murmur that is continuous, louder in systole, and located at the upper left sternal border.

Ejection (crescendo-decrescendo) murmurs are caused by ventricular outflow obstruction. Ejection murmurs begin after the first heart sound.

Differentiation of Normal from Pathologic Murmurs

Criteria for Diagnosis of a Normal Heart Murmur

Asymptomatic patient.

No evidence of associated cardiac abnormalities, extracardiac congenital malformations, or syndromes.

Auscultatory features are characteristic of an innocent murmur.

Normal Murmurs

Type

Shape

Timing

Pitch

Location

Other Findings

Vibratory

Ejection

Midsystolic

Low

LLSB-apex

Intensity < grade II

Venous hum

Diamond

Continuous

Medium

Subclavicular

Disappears in supine position

Pulmonary flow Flow Systolic Medium ULSB Normal S2 split

Physiologic branch pulmonary artery stenosis

Ejection Systolic Medium Entire chest Disappears by 4 to 6 months of age
LLSB = lower left sternal border, ULSB = upper left sternal border, S2 = second heart sound.

Heart Murmurs in the Newborn Infant

Sixty percent of healthy term newborn infants have normal heart murmurs. One third of neonates who have serious heart malformations may not have a detectable heart murmur during the first 2 weeks of life.

Thirty percent of newborn infants subsequently determined to have heart disease are discharged from the newborn nursery as ostensibly healthy.

Persistent peaceful tachypnea should not be dismissed; 90% of infants who have serious cardiac disease have persistent tachypnea after birth.

A persistently hyperdynamic precordium suggests organic heart disease.

Auscultation of the Second Heart Sound. In healthy neonates, the second heart sound is split audibly by 12 hours of age. In general, a split second heart sound signifies the normal presence of two outflow tract valves as well as an appropriate reduction in pulmonary vascular resistance. A single second heart sound in a quiet neonate indicates: 1) the absence of one outflow tract valve (aortic or pulmonary atresia); 2) an abnormal position of the great vessels (transposition of the great arteries or tetralogy of Fallot); or 3) pulmonary hypertension (ventricular defect, persistent pulmonary hypertension).

Neonates who have critical heart disease almost always have an audibly single and often accentuated second heart sound.