Why is the left atrial “v” wave taller than right atrial “v”wave ?

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

1. 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)
2. Apart from relative thinness,* right atrial volume is more , hence  it can  accommodate more volume without rasing its pressure .
3. 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  .
4. Further ,the adjoining  systemic  left ventricle  ,  adds up to the stiffness of  left atrial   filling .

(*Thickness of RA -2mm,  LA -3mm )

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