Hypertrophic Cardiomyopathy

What is it?

Hypertrophic cardiomyopathy is a disease characterized by hypertrophy limited to the LV, and often to the basal portion of the ventricular septum. The LV is not dilated unless there is a separate cause.

Hypertrophic cardiomyopathy is found in one in every 500 people. It’s the most common reason for sudden cardiac¬†death (SCD) in young adults.

In hypertrophic cardiomyopathy, changes are the result of a genetic anomaly. Ventricular changes are usually asymmetrical, with hypertrophy predominantly affecting the ventricular septum. The increase in wall thickness may include the entire septum or just the basal septum. Often the septum increases to twice its normal size.

Diagnostics
  • ECHO
    • Evaluates cardiac function, extent of hypertrophy, presence and severity of mitral regurgitation, and outflow tract obstruction
  • ECG
    • Identifies dysrhythmias
  • MRI
    • Used when ECHO findings are inconclusive. It helps define the extent and distribution of hypertrophy and the effects on mitral valve structures.
Positive Inotropes

Any medication that increases contractility should be avoided due to life-threatening consequences. Medications that increase contractility that should be avoided are:

  • Digoxin (Lanoxin)
  • Dobutamine (Dobutrex)
  • Dopamine (Intropin)
  • Milrinone (Primacor)
  • Epinephrine
  • Norepinephrine (Levophed)
Medications For Treatment
  • Improve ventricular filling
    • Beta blockers (decrease HR, increase diastolic filling time)
    • Calcium channel blockers (decrease ventricular wall tension)
    • Maintain adequate preload to support ventricular filling
    • Convert atrial fibrillation to normal sinus rhythm. A-fib is the most common dysrhythmia¬†associated with this condition.
  • Optimize stroke volume
    • Decrease contractility for symptomatic patients with or without obstruction
    • Provide beta blockers as first-line therapy
    • Provide calcium channel blockers as a second-line therapy
  • AVOID
    • Medications that increase contractility or decrease afterload. These effects can be life-threatening, as they increase outflow obstruction and greatly decrease CO.
Beta Blockers

Beta blockers, such as metoprolol tartrate (Lopressor) or metoprolol succinate (Toprol), decrease contractility and increase the duration of diastole.

Calcium Channel Blockers

Verapamil (Calan) is a calcium channel blocker of choice. It decreases ventricular contractility and improves myocardial relaxation, resulting in increased ventricular filling. It also helps control ventricular rate if atrial fibrillation occurs.

Antidysrhythmics

Amiodarone (Cordarone) is useful in treating ventricular or atrial dysrhythmias in both obstructive and non-obstructive hypertrophic cardiomyopathy patients.

Alternative Treatments
  • Ventricular Septal Myectomy
    • Surgical procedure enlarges outflow tract and alleviates outflow obstruction by removing a portion of the hypertrophied septum.
  • Percutaneous Alcohol Septal Ablation
    • Non-surgical
    • Catheter is advanced into a septal branch providing blood flow to the septum, ethyl alcohol is injected
    • Ethyl alcohol infiltrates the surrounding myocardial tissue, causing a controlled MI of the septum. The tissue necroses and then becomes fibrotic tissue.
    • The reduction in tissue size does not occur immediately and may continue to have effects on ventricular outflow for up to one year post-op.