Aortic Stenosis - 2

Aortic Stenosis - CardioNotes 2

Introduction

Aortic Stenosis is the most common cause of left ventricular outflow tract obstruction. It is most often is due to calcification of a congenitally bicuspid or normal trileaflet valve. Calcific changes are felt to be caused by an active disease process characterized by lipid accumulation, inflammation, and calcification

Signs and Symptoms

The presence of symptoms with aortic stenosis usually indicate that the AS is severe The most common symptoms include angina, syncope, and heart failure. Aortic stenosis often is first diagnosed by the finding of a murmur on exam. However, while a soft murmur with a preserved S2 reliably excludes severe stenosis and a severe grade 4 murmur with diminished carotid upstrokes confirms severe obstruction, between these extremes physical examination is not accurate for evaluation of disease severity.

Causes

Bicuspid Aortic Valve, Unicuspid, and quadricuspid Aortic Valves
Calcified
Look for Supravalvular Stenosis, Subaortic Membrane, and HOCM

Echocardiographic Assessment

Obtain maximal aortic jet velocity 4V²
Calculate mean gradient by measuring VTI or 2.4V²
Obtain LVOT gradient and velocity 1 cm proximal to the aortic valve with pulse wave Doppler
Calculate Aortic Valve Area=d² x 0.785 x LVOT VTI (pulse wave)/ AV VTI (Cw)
Calculate dimensionless index (0.25 is severe)
Aortic velocity is the most reproducible and is the strongest predictor of clinical outcome. Aortic velocity allows classification of stenosis as mild (2.6 to 3.0 m/s), moderate (3 to 4 m/s), or severe (>4 m/s). Leaflet thickening and calcification with adequate leaflet motion and a velocity <2.5 m/s is called aortic sclerosis.

Classification of Severity

Classification of Severity
Indicator	Mild	Moderate	Severe
Jet Velocity	Less than 3	3 -4	>4
Mean Gradient (mm Hg)	<25	25-40	>40

Indications for Surgery

Symptoms are needed in most patients with AS which includes angina, syncope, or heart failure.
In the absence of symptoms the following are indications
- Need for High Risk Operation
- Severe CAD with concominant CABG
- Left Ventricular Dysfunction