CPC

Hypertrophic Cardiomyopathy

FACTS of INTEREST

• Patient was relatively asymptomatic until follow-up visit at WRAMC.

• Both his mother and older sibling had hypertrophic cardiomyopathy but were asymptomatic and without evidence of obstruction. His father’s echo was completely wnl

FACTS cont.

• His ECG showed voltage criteria for LVE but there was no evidence of LV strain pattern.

• His preop echo showed a midcavity gradient of 100 mm HG.

• The diagnostic portion of his EP study showed : LV 182/19,AAo 90/41,DAo 90/40

OPERATION: Morrow Procedure

• Myotomy and myectomy of the intraventricular septum.

• After an initial myectomy ,the gradient was felt to be 35 but as the heart warmed up and perfused better, the gradient was 50.

• Surgeons went back in, took out more tissue and patient had gradient of 15.

POST OP

• Following the surgery, the patient was found to have a residual gradient of about 30,depending on his level of agitation.

• He returned to being without symptoms. His preop MR had been significantly reduced, his subAS (HOCM) was significantly reduced, and his AI was slightly worse.

• About 2.5 yrs later, his gradient was 30.

POST OP

• Following the surgery, the patient was found to have a residual gradient of about 30,depending on his level of agitation.

• He returned to being without symptoms. His preop MR had been significantly reduced, his subAS (HOCM) was significantly reduced, and his AI was slightly worse.

• About 2.5 yrs later, his gradient was 30.

POSTOP

• Patient has LBBB on ECG

• Holter 2 yrs post op shows no significant rhythm disturbances. When running,however, he looks a lot like V.Tach

• Patient remains on verapamil

DISCUSSION

• General: about .1-.2% of general population

• At least 50-70 different names

• Things it ain’t: secondary hypertrophy,IDM,glycogen storage diseases,acromegaly, myocardial Fe deposition,athletic heart syndrome

GENETICS

• Probably autosomal dominant with variable penetrance

• Familial in at least 50% of patients

• Seems to usually involve missense genes on the B myosin heavy chain.

• There are about 1k genes response for myocardial growth which may be why there’s so much variation in families.

PATHOPHYSIOLOGY

• Although the massive hypertrophy would seem to mainly affect systolic function, the pathonomonic aberration is in diastolic relaxation.

• The ventrical is noncompliant because of increased muscle mass and fibrosis. Also the coronaries are not well perfused during diastole

PATHOPHYSIOLOGY cont.

• A large part of the LVOT obstruction is because the anterior leaflet of the MV gets in the way during systole(SAM). People who are obstructed seem to have a more anterior placement of their MV.

• People who are obstructed also seem to have a more narrow LVOT in and of itself.

NATIONAL HX• Mortality is twice as high in children.

• 50% who present in infancy die by 1 yr. 25% will eventually die.

• If you present after 1 yr the risk of failure is lessened but the risk of sudden death is higher.

• Hard to predict based on degree of hypertrophy but the degree of obstruction is

• a factor.

NATIONAL HX cont.

• There seem to be groups with no obstruction and only minimal gradient.

• HOCM is the most common cause of death during exercise in children and adolescents.May be as high as 5-7%/yr.

• Most common age is 10-35 yrs.

• Only selectors seem to be family hx and recurrent syncope.

CLINICAL

• Murmur, chest pain,fatigue,syncope, palpitations and dizziness.

• Murmur is harsh and peaks in midsystole. Usually louder the more obstruction. There is a blowing holosystolic murmur at the apex which is the MR. This murmur is increased by standing(decreased preload,Valsalva(decreased pre and afterload.

CLINICAL

• The MR murmur is decreased by lying down(increased preload), squatting(increased afterload) or verapamil.

• The ECG is abnormal in most cases with 95% of obstructive cases being abnormal. 25% of patients without obstruction may be normal.

• Infants may have cardiomegaly on CXR

CLINICAL cont.

• Echo is the mainstay of diagnosis and follow-up. Asymmetrical septal hypertrophy and SAM are felt to be 95% specific for HCM.

• ECHO can be used to separate from athletic heart syndrome. In the latter,the LV free wall seldom >15mm and thickness decreases with cessation of training.

CLINICAL cont

• Invasive: ECHO probably better for fu but cath good for assessing degree of LV diastolic dysfunction. Also good for showing degree of midcavity obstruction.

TREATMENT

• Beta blockers for tx of symptoms. They appear to have no effect on the degree of LVOT obstruction or frequency of sudden death.

• Works by prolonging diastole and decreasing heart rate. Also decrease contractility.

TREATMENT cont.

• Calcium channel blockers: decrease contractility and increase diastolic function.

• Verapamil : may be best but has been associated with death in infants.Use carefully if evidence of conduction disturbances.

• Nifedipine:big vasodilator. May be bad in obstructed infants.

TREATMENT cont.

• Avoid digitalis and other inotropes as they may make obstruction worse. Remember patients do better with a good preload so diuretics may make them worse.

• Surgery: most effective. Complications include complete heart block,septal perforation, and inadequate. A point of debate is whether to pull the MV as it relieves obs.

TREATMENT cont.

• DDD pacing in the ventricular apex may relieve symptoms but the method is uncertain. This was the tx EP approach used in our patient without success.

• Other option is to use amiodirone to tx v.tach but not clearly related to decreased death. Also helps with a.fib.

TREATMENT final

• Ami, myectomy and implantable pacemakers may be the approach for patients with inducible v. tach.