Why is the left atrial “v” wave taller than right atrial “v”wave ?
Posted Sep 24 2011 11:11am
We know the atrial pressure wave forms vary between right and left atrium .In the right atrium ”a” waves are prominent and taller than “v” waves, while the reverse is true in left atrium .
Typical filling pattern of Right side chambers .Note The tall A waves . Source : http://www.ncbi.nlm.nih.gov/books/NBK2213/
Note the left atrial a waves are diminutive and v waves are tall .The dark black wave is pulmonary venous waves. Source :http://heart.bmj.com/content/89/2/231.full
The reasons for tall left atrial v waves are
V waves are passive atrial filling waves and are timed during ventricular systole .Left atrium is relatively thick *,stiff , less compliant chamber .( Compliance : Rate of raise of pressure per unit change in volume is high)
Apart from relative thinness,* right atrial volume is more , hence it can accommodate more volume without rasing its pressure .
The left atrium is decompressed by relatively stiff pulmonary veins with a mean pressure of 8 mmhg , can not adequately dampen the refluxing tides of v waves , while the low pressure vena cava of RA dampen the right atrial v waves with ease .
Further ,the adjoining systemic left ventricle , adds up to the stiffness of left atrial filling .