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 in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.
After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.
He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.
His one great achievement is being the father of two amazing children.
On Twitter, he is @precordialthump.
| INTENSIVE | RAGE | Resuscitology | SMACC