Calculation of LVSP & LA
hello! welcome to mastering and guidelines in ultrasound and echo. Answers to
questions; Question seven: calculation of left ventricular systolic pressure
and left atrial pressure by knowing blood pressure and mitral regurgitation
velocity . question seven: in a patient with systolic blood pressure 150 over 90
mmHg and the V-max of MR 5 meter per second, how much will be left ventricular systolic pressure
and left atrial pressure? if we remember the
Pascal law in
any confined fluid systems the pressure in anywhere of that system is equal and even. like this
pressure on any spot of this confined fluid system is equal. Now! let's
see in heart. In heart has two confined fluid systems too: left side and right
side. in left side during systolic phase blood pressure in left ventricular
is equal to the aorta and major artery including arm. so if we measure blood
pressure on the arm or any other major artery close to the heart it will be equal systolic blood pressure.so
l left ventricular systolic pressure will be equal blood systolic pressure.
so in this case systolic blood pressure is 150 so left
LVSP will be 150 mmHg too. now let's see what about about left
atrial pressure? what about that? during systole left ventricular has a pressure
that's equal systolic blood pressure and try to push in MR blood to the left
atrium. in other side the pulmonary vein system has a pressure that pushes the
blood to the left atrium and try to push the blood goes to the left ventricular
so the left atrial pressure is against left ventricular pressure. in this way
with knowing this two of them we can calculate the third one. so in this case
left atrial pressure will be systolic blood pressure or left ventricular
systolic pressure minus mitral regurgitation pressure gradient and with
the Bernoulli equation... if we know the v-max of MR we can calculate
pressure gradient of that jet. so in this case
MR v-max is 5 so pressure gradient of M R will be hundred and systolic blood
pressure is 150 the differences between them become 50 mmHg . so left
atrial pressure is 50 mmHg is almost very high. let me put it in this
simple way, so you remember it forever. imagine the blood here, car as blood and
right side is left ventricular and left side is left atrium. so those
forces are against each other. if we know two of these three elements: the pressure
of the blood goes to the left atrium and this left ventricular pressure and left
atrial pressure; if we know two of those three elements we can calculate very
easy the third one. in this case if we have left ventricular knowing and the
velocity of the blood the this two, we can measure left atrial very easy. and that
here we calculated 50 mmHg as elevated in this case