ACEP ID:

Pediatric Emergency Medicine

Pearls & Pitfalls - HPI: More than Meets the Eye (or the Forehead)

Larry Mellick, MD, MS, FAAP, FACEP
Professor of Emergency Medicine
Medical College of Georgia

Jennifer E. Tucker, MD, FAAP
Assistant Professor of Emergency Medicine and Pediatrics
Medical College of Georgia
 

Pearl: In patients presenting with a history of head injury with loss of consciousness (LOC), remember that the LOC actually may precede the head injury.

Presentation: A 7-year-old male presented to the pediatric emergency department fully spinally immobilized after suffering a head injury. By report, he had been running in gym class and struck a wall with his head. According to his gym teacher, the patient collapsed, was allegedly pulseless, and required CPR (including chest compressions for 2-3 minutes). Upon arrival of the paramedics, the patient was awake and alert with stable vital signs and no memory of the event. The patient underwent a pediatric trauma team evaluation, including c-spine films and a head CT. After the negative trauma team evaluation, the patient's care was transferred to the pediatric emergency medicine team. His initial physical examination was notable for a small amount of erythema on the center of his forehead and a II/VI mid to late systolic murmur heard throughout the precordium. His S2 was prominent and exhibited normal splitting. Given the history of a fall with an impressive loss of consciousness (pulseless) but no external sequelae of significant head trauma, the pediatric emergency medicine physician obtained a 12-lead EKG, which revealed biventricular hypertrophy and prominent Q waves in the lateral and inferior leads.

Upon further questioning, the patient's father reported a family history of "that condition where you have abnormal enlargement of the muscle in your heart. I have that and so do my sister and her two daughters." The father reported multiple personal episodes of syncope, including while driving, but has been asymptomatic for seven years while on verapamil. At that point, the cardiologist was called, and an echocardiogram revealed asymmetric septal hypertrophy without left ventricular outflow obstruction; hypertrophic left ventricular systolic dysfunction with a shortening fraction of 34%; abnormal diastolic dysfunction; and trivial mitral, tricuspid, and pulmonary regurgitation.

The patient was subsequently hospitalized for 2 days and placed on atenolol. An inpatient holter monitor revealed no ectopy. One month after discharge, the patient was seen in clinic where an EKG revealed sinus bradycardia and biventricular hypertrophy. The cardiologist recommended implantation of a cardiac defibrillator.

Diagnosis: Hypertrophic cardiomyopathy

Discussion: Hypertrophic cardiomyopathy was recognized initially in 1868 but was officially described pathologically by Teare in 1958.1 The prevalence throughout the world is 0.2% (1 in 500). It represents the most common genetic cardiovascular disease worldwide,2 accounting for 20-30% of all cases of pediatric primary myocardial disease.3 Hypertrophic cardiomyopathy is an autosomal dominant trait caused by any one of 10 genes that encode proteins of the cardiac sarcomere.4 Penetrance is believed to be incomplete during childhood and adolescence and nearly complete in adulthood. It is the most common cause of sudden cardiac death in young adults, and the annual mortality is about 2-4%. It occurs most commonly in adolescents and young adults ranging in age from 15 to 35 years. Many patients are asymptomatic or only mildly symptomatic before death. Previous syncopal episodes have been shown to predict sudden death.

Patients typically present with fatigue, chest pain, palpitations, syncope (our patient, likely secondary to arrhythmia), impaired consciousness, or sudden death. The physical examination generally is notable for a normal first heart sound with a normal split of the second heart sound. With significant obstruction of the left ventricular outflow tract, there may be paradoxical splitting. Systolic ejection murmurs are discovered in about 40% of patients. Typically, the murmur begins well after the first heart sound and is most pronounced between the mid-retrosternal region and the apex. Maneuvers that increase contractility or decrease preload or afterload may augment the murmur (exercise, standing, Valsalva, digitalis, nitroglycerin). The murmur of hypertrophic cardiomyopathy typically is decreased by squatting, handgrip, alpha agonists, beta blockers, and general anesthesia. Nevertheless, 25% of patients have a completely normal auscultatory examination.

In terms of pathology, the most common gross finding is a hypertrophied and non-dilated left ventricle. The hypertrophy is typically asymmetric. In 55-60% of patients, the hypertrophy involves the interventricular septum and portions of the anterolateral free wall, with the posterior segment of the free wall affected the least. In terms of histology, the heart exhibits cardiac muscle cell disorganization, abnormalities of the small intramural coronary arteries, and myocyte hypertrophy. The pathophysiology consists of diastolic dysfunction, systolic dysfunction, left ventricular outflow obstruction, coronary artery abnormalities leading to myocardial ischemia, and arrhythmias (atrial fibrillation, ventricular tachycardia, and ventricular fibrillation).

The diagnosis generally is made with physical examination, chest x-ray (presence of cardiomegaly), electrocardiography, and echocardiography. EKGs are abnormal in all infants and in more than 90% of children, but findings generally are nonspecific. Infants tend to exhibit biventricular hypertrophy, while children have left ventricular hypertrophy. Both groups may demonstrate nonspecific ST-segment and T-wave changes. Echocardiography identifies the extent of hypertrophy and the significance of obstruction and will also assess the ventricular systolic and diastolic function. The measurement of the septal thickness based on weight is used to make the diagnosis in children.

Therapies consist of calcium channel blockers (CCBs) and beta-blockers. CCBs decrease the systolic gradient and improve diastolic filling while decreasing myocardial oxygen consumption. It is unknown whether they protect against sudden death, and they are associated with an increased incidence of sudden death in children younger than 1 year of age. Beta-blockers are effective for symptoms by reducing heart rate, left ventricular contractility, and wall stress through their sympatholytic effects. They have no effect on the extent of the hypertrophy, the progression toward hypertrophy, or reduction of ventricular arrhythmias. They do not eliminate the risk for sudden death. Active sports participation is not recommended because most sudden death in adolescents occurs during or after exercise. The most efficacious treatment modality for the high-risk patient who has hypertrophic cardiomyopathy is the implantable cardioverter-defibrillator (ICD). This therapy also has the potential to affect the natural history of the disease. In a large multi-center study, ICDs aborted potentially lethal ventricular tachyarrhythmias and restored sinus rhythm in almost 25% of patients during a 3-year period.1 They are strongly recommended for any patient with a history of cardiac arrest or sustained and spontaneously occurring ventricular tachycardia.

References:  

  1. Maron, BJ. Hypertrophic cardiomyopathy in childhood. Pediatr Clin N Am 2004(51):1305-1346.
  2. Kelly, BS, Mattu, A, Brady, WJ. Hypertrophic cardiomyopathy: electrocardiographic manifestations and other important considerations for the emergency physician. Am J Emerg Med 2007(25):72-79.
  3. Towbin, JA. Pediatric myocardial disease. Pediatr Clin N Am 1999;46(2): 289-312.
  4. Kelly, BS, Mattu, A, Brady, WJ. Hypertrophic cardiomyopathy: electrocardiographic manifestations and other important considerations for the emergency physician. Am J Emerg Med 2007(25):72-79.

 

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