Cardiac murmur - is every murmur pathological?

Abstract

This statement aims to help physicians distinguish between innocent and pathological precordial murmurs that require further cardiological evaluation.
Auscultation is just one part of the physical examination and follows a detailed medical history. It is important to gather information about the prenatal and perinatal period, previous somatic and psychomotor development, presence of congenital anomalies, episodes of cyanosis, respiratory infections, exercise intolerance, loss of consciousness, neurological symptoms, and medication use. Previous auscultatory findings should also be considered. Family history should focus on congenital heart defects, hereditary syndromes, cardiomyopathies, and sudden deaths.
The most important aspect of the physical examination is assessing the child’s general condition, including nutritional status, respiratory status, and growth and development. Central cyanosis may indicate right-to-left shunting, while pale and sweaty skin can suggest heart failure. Phenotypic characteristics and associated congenital anomalies may point to specific genetic syndromes. Chest wall deformities can indicate connective tissue disease, while a protruding chest may suggest cardiomegaly. Clubbing of the fingers is a sign of chronic hypoxia. Peripheral edema and ascites should be noted, and liver palpation is necessary. Weak peripheral pulses with tachycardia may indicate shock. If pulses are absent in the lower extremities, aortic coarctation should be considered. Oxygen saturation and blood pressure should be measured in all children over three years old, and in younger children if needed (1-3)
Before auscultation in older and cooperative children, palpation of the precordium, jugular notch, and neck is recommended to detect hyperdynamic precordium due to volume overload or flow turbulence.
Heart auscultation is performed over four standard auscultation points, as shown in Figure 1.
During auscultation, heart sounds should be evaluated. In a healthy heart, they are clear and distinct. The second heart sound (S2), caused by semilunar valve closure, is physiologically split depending on respiration. A widely split S2 may indicate pulmonary stenosis or right bundle branch block, while a fixed split S2 suggests atrial septal defect. The third heart sound (S3) is best heard at the apex and may be normal in children and young adults, as it occurs due to rapid ventricular filling. However, it may also indicate ventricular dilation and reduced compliance. The fourth heart sound (S4) is always pathological and results from strong atrial contraction against a stiff ventricle. A gallop rhythm, which combines a loud S3 or S4 with tachycardia, is always pathological.
Additional heart sounds may also be heard. Ejection clicks resemble S1 splitting and are best heard at the heart base, indicating semilunar valve stenosis or dilated great arteries. Mid-systolic clicks, best heard at the apex, indicate mitral valve prolapse. Opening snaps, associated with mitral stenosis, occur after S2 and are best heard at the apex (1-3).
Precordial murmurs should be described based on their intensity, type, location, radiation, and quality. The grading of systolic murmurs by intensity is shown in Table 1. Table 2 lists pathological conditions associated with specific murmurs.
Over 80% of children present with an innocent murmur at some point in childhood. It is crucial to differentiate these from pathological murmurs to avoid unnecessary concern for families and excessive healthcare expenses. Innocent murmurs reflect hemodynamic changes during normal growth and development and become more pronounced in conditions with increased metabolic demand, such as fever or anemia. Innocent murmurs are shown in Figure 1. Except for venous hum, which is continuous and changes intensity with head movement, innocent murmurs are systolic, non-turbulent, soft, and musical, and are best heard in the supine position (1-3).
Structural heart disease is more likely if a murmur is holosystolic or diastolic, grade 3 intensity or louder, accompanied by a click, louder in the standing position, or harsh in quality (1-3).
A newborn with a persistent murmur should always be referred for an echocardiogram (4). In older children, if a murmur has characteristics of an innocent murmur and ECG is normal, the likelihood of structural heart disease is low. However, if there is any doubt about whether the murmur is pathological, echocardiographic evaluation is warranted (1-3).