Heart Murmurs

Case

At the one year check-up of a patient you have followed since birth you detect a 2/6 systolic murmur at the LLSB that you had not noted before. The blood pressure and pulses are normal and the child has gained and grown well. How would you decide that this is an innocent murmur and what do you tell the parents?

The majority of murmurs heard by the pediatric practitioner are functional or innocent. By history, physical exam, careful examination, you should be able to make the differentiation.

History

  1. patterns. FTT
  2. Family history of cardiac lesions
  3. In infants- feeding difficulties, tachypnea, irritability, sweating
  4. Older children- exercise intolerance, syncope, chest pain
  5. Birth history- prenatal conditions, exposure to drugs in pregnancy 
  6. History of other anomalies
  7. History consistent with underlying anemia or symptoms of hyperthyroidism
Physical Exam
  1. Presence of non-cardiac malformations. Incidence of congenital heart disease increase with other anomalies
  2. Active or hyperdynamic precordium. You must palpate the chest.
  3. Cyanosis
  4. Pulses- decreased or bounding.
  5. BP and difference in upper and lower extremities
  6. Signs of CHF- tachypnea, liver enlargement, rales, periorbital edema
  7. Intensity of murmur, location, does it change with position, continuous, diastolic often are associated with anatomical lesions. Where in cycle it occurs
  8. Second heart sound- intensity, splitting of 2nd heart sound. Usually with increased pulmonary pressure, the 2nd sound will become louder and single.
  9. Gallops
  10. Clicks
  11. need to reevaluate the patient when they are cooperative and quiet. Examine the child while asleep or relaxed and not tachycardiac.
Normal Murmurs
  1. Venous hums- usually continuous and disappear in supine position. Heard best under clavicles. Due to turbulence in the jugular venous system.
  2. Carotid bruits- base of the neck 
  3. Pulmonary flow- ULSB. Due to turbulence from the pulmonary artery ejection 
  4. Vibratory- LLSB- high pitched and less than grade 2. Doesn't radiate. Changes with position of the child. Intensity will increase with exercise, fever, and excitement.
It is the job of the general pediatrician to differentiate functional from pathologic conditions. It is not unusual for an innocent murmur to sound pathological when the heart rate increase during exercise or the presence of a fever. It is essential to inform the parents and the patient that they have an innocent murmur and if they see a new physician, they will not be sent for an unnecessary evaluation. The explanation must emphasize that the child's activities should not be limited and the murmur will not affect the child's future growth and health. Also, there is no special follow-up required. Anxious parents may insist on a consultation by a pediatric cardiologist.

Often, newborns will have normal cardiac exams in the nursery and present for their 2 week checkup with a significant murmur. Infants with murmurs detected in the nursery will later have normal exams. The practitioner should be aware of subtle findings that may point towards cardiac disease. Tachypnea and hyperdynamic precordium should alert the pediatrician. Any feeding problems should also make you think of a cardiac lesion. Attention to the second heart sound in neonates is very important. A split second sound should be present by 12-24 hours of life and its presence signifies 2 semilunar valves and a fall in pulmonary vascular pressure. 

Reference

  1. Birkebaek NH et al. Chest Roentgentogram in the Evaluation of Heart Defects in Asymptomatic Infancts and Children With a Cardiac Murmur: Reproducibility and Accuracy. Pediatrics. 1999; 103(2):e15.
  2. Harris, J. Peter. Evaluation of Heart Murmurs. Pediatrics in Review. December 1994.
  3. Pelech AN. Evaluation of the Pediatric Patient with a Cardiac Murmur. Pediatric Clinics of North America. 1999; 46(2):167-188.
  4. Sapin SO. Recognizing Normal Heart Murmurs: A Logic-based Mnemonic. Pediatrics. 1997; 616-619.
  5. Swenson JM et al. Are Chest Radiographs and Electrocardiograms Still Valuable in Evaluating New Pediatric Patients With Heart Murmurs or Chest Pain? Pediatrics. 1997; 99(1):1-3.