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 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 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.