Obstruction can be
- valvular (most common)
— continuous wave Doppler allows peak velocity to be measured -> peak gradient can be calculated using Bernoulli equation
— peak gradient = 4 x peak velocity across the narrowing squared
— normal peak gradient < 10mmHg, critical > 70mmHg
— gradient measurements are very dependent on ventricular function so can be misleading.
— normal 2.5-5.5 cm2
— critical < 0.92 cm2
- dimensionless severity index = ratio of LVOT velocity/aortic valve velocity (V1/V2)
— provides a dimensionless measurement of aortic stenosis which is independent of Q
— < 0.25 implies a valve area of 0.75cm2 (severe AS)
— LV hypertrophy or dilation
— LV systolic and diastolic dysfunction
— post-stenotic dilation
CATEGORIES OF AORTIC STENOSIS SEVERITY
From Vahanian et al, 2010:
References and links
- Vahanian A, Otto CM. Risk stratification of patients with aortic stenosis. Eur Heart J. 2010 Feb;31(4):416-23. PMID: 20047994
Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a 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 three amazing children.
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