Hypertrophic Cardiomyopathy
Reviewed and revised 1 September 2014
OVERVIEW
- aetiology unknown (>50% autosomal dominant condition)
- hypertrophied septum can cause dynamic left ventricular outflow tract obstruction (LVOTO) during systole
- also can get dynamic anterior motion of the mitral valve leaflet towards septum (SAM – systolic anterior motion) -> causing further obstruction
- this causes a pressure overload of LV and diastolic dysfunction
ASSESSMENT
History
- syncope, presyncope, dizziness
- angina
- symptoms of heart failure e.g. orthopnea, paroxysmal nocturnal dyspnea
- palpitations
- sudden death
Examination
- double or even triple apical impulse
- evidence of heart failure
- jerky pulse
- S2 may be paradoxically split if very high LVOT gradient
- prominent a wave on JVP due to decreased RV compliance
- Systolic ejection murmur (due to LVOTO)
- typically is a systolic ejection crescendo-decrescendo murmur
- best heard between the apex and left sternal border and radiates to the suprasternal notch but not to the carotid arteries or neck
- dynamic maneuvres: quieter with increase in preload (eg, squatting) or increase in afterload (eg, handgrip), louder with any decrease in preload (eg, Valsalva maneuver, nitrate administration, diuretic administration, standing) or with any decrease in afterload (eg, vasodilator administration)
- Holosystolic murmur at the apex and axilla (mitral regurgitation due to systolic anterior motion of the mitral valve and significant LV outflow gradients)
- Diastolic decrescendo murmur (aortic reurgitation) heard in 10% of patients,
Investigations
- ECG:
-> LVH critieria
-> deep anterior lateral TWI
-> dagger-like Q waves in infero-lateral leads - ECHO:
-> asymmetric septal hypertrophy
-> systolic anterior movement of the mitral valve
-> early aortic valve closure
MANAGEMENT
- see LVOTO (below)
- myomectcomy
Intraoperative
- goal = maintain a large, slow ventricle
- low normal HR
- adequate volume loading
- high normal SVR
- low ventricular contractility
- avoid inotropes
- betablockers
- calcium channel blockers
- aggressive management of arrhythmias (may require pacing)
- direct vasopressors
- invasive monitoring
References and Links
- LITFL CCC — Left ventricular outflow tract obstruction (LVOTO)
- LITFL ECG Library — Hypertrophic Cardiomyopathy
- Scancrit — Systolic anterior motion (SAM)
Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the Clinician Educator Incubator programme, and a CICM First Part Examiner.
He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.
His one great achievement is being the father of three amazing children.
On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.
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