Hypertrophic cardiomyopathy

Question 1

HOCM pathophysiology

Answer 1

-1 in 500 people
-Abnormal thickening (hypertrophy) of the left ventricle, often asymmetric or localized (apex/septum- obstructs outflow).
-Caused by expansion of the extracellular space and myocyte disarray/fibrosis
-Cardiac sarcomere gene mutation in 60-70%, normally autosomal dominant
-Symptoms / prognosis depends upon the localization of thickening
=Obstructive (septum)
=apical

Question 2

Symptoms HOCM

Answer 2

-Chest pain / angina
-Breathlessness
-Syncope
-Palpitation (AF)
-Heart Failure, oedema

-May present with arrhythmia or sudden cardiac death.

Question 3

Clinical signs HOCM

Answer 3

-Clinical examination may be normal.
-Irregularly irregular pulse
-Double apical impulse (stiff heart, double pulsation in diastole as increased pressure to fill heart and forceful contraction of atria)
-Ejection systolic murmur
=May be late-peaking

Question 4

Investigations HOCM

Answer 4

-ECG
=always abnormal, fixed widespread T-wave inversion (abnormal repolarisation), tall QRS complexes (lateral leads)
-Echocardiogram
=Asymmetric hypertrophy
-Cardiac MRI
=Confirms diagnosis (tissue characterisation)
=Looks for scar
-Ambulatory ECG (48hrs, to rule out non-sustained ventricular tachycardia)

Question 5

Treatment HOCM

Answer 5

-No medication effective to treat / prevent the hypertrophy
-Beta-blockers/ calcium channel blockers
=reduce myocardial contractility and prevents arrhythmia
-Disopyramide
=Class 1a anti-arrhythmic agent and negative inotropic (reduces forcefulness of contraction therefore obstruction)
-Anti-coagulation if atrial fibrillation
-Heart failure medication

Question 6

Prognosis and long-term care HOCM

Answer 6

-Aim to reduce symptoms
=Beta-blocker / disopyramide
=Septal reduction therapy (myectomy (scalpel), alcohol septal ablation- induce MI in area)
-Consider implantable defibrillator based on risk of SCD (RV)
-Genotype and screen 1st degree relatives
-Rarely may be considered for cardiac transplantation

Question 7

Risk factors for sudden cardiac death

Answer 7

-Age
-Maximum LV wall thickness
-Left atrial size
-Severity of LVOT obstruction
-Family history of sudden cardiac death
-Non-sustained VT
-Unexplained syncope
-?Amount of myocardial scar

Question 8

Other causes of LV hypertrophy

Answer 8

-Hypertension
-Athletic training
-Aortic stenosis
-Amyloidosis
-Fabry’s disease / metabolic disorders

Question 9

Downsides to implanting cardiac defibrillator

Answer 9

-Implantation risks
=Pneumothorax, haematoma, cardiac tamponade, pain
-Long-term device risks
=Infection, pacemaker lead failure, repeated battery changes
-Cosmetic reasons
-Inappropriate shocks