Friday, April 20, 2012

Pulmonary Hypertension

Cardiac ultrasound can be used to show the presence of pulmonary hypertension if there is a tricuspid insufficiency, pulmonary stenosis, or pulmonary insufficiency.  Continuous Wave Doppler is used to determine the velocity and pressure gradient of the valvular flow.  Pulsed Wave Doppler is not capable of measuring higher flow rates.  Pressure gradient indicates the difference between the pumping chamber (the right ventricle in this case) and the receiving chamber (either the right atrium in tricuspid insufficiency or the pulmonary artery in pulmonary stenosis).  A pressure gradient of 10-50 mm Hg is considered to mild pulmonary hypertension, 50-80 mm Hg is moderate, and greater than 80 mm Hg is severe.

Radiographs can also be used to show more severe pulmonary hypertension.  If the anterior pulmonary arteries are larger than the veins on the lateral views, pulmonary hypertension is present.  On the VD or DV views, the caudal pulmonary arteries will be larger than the veins.     

There seems to be some confusion about treatment of pulmonary hypertension.  Some recent lectures have unintentionally given the idea that all cases must be treated and that Viagra is the treatment.  First, show that pulmonary hypertension is present.  Then, identify and treat the cause of the hypertension.

If heartworm disease is present, treat the heartworm disease.  If pneumonia is present, treat the pneumonia, etc.

If pulmonary valve stenosis is present, mild cases (PG of 10-50 mm Hg) are not treated.  The patient will probably live a full life without symptoms or need for treatment.  In moderate to severe cases, ballon valvuloplasty can be done to partially relieve the stenosis.

Pulmonary hypertension is a secondary problem with mitral insufficiency or mitral stenosis because blood backs up to the lungs.  The right ventricle must pump against the increased resistance of the mitral insufficiency.  The presence of a tricuspid insufficiency allows us to use Continuous Wave Doppler to estimate the pressure of the right ventricle.  Normal pressure in the right ventricle is 20 mm Hg and a pressure of 30 mm Hg or higher is considered to represent pulmonary hypertension.  Usually, treatment of the mitral insufficiency will also treat the pulmonary hypertension.  

Viagra is usually only used in the last 30 days of the patient's life when end stage disease results in uncontrollable pleural effusion.  This can be seen in , end stage heart disease (severe mitral insufficiency, tricuspid insufficiency, pulmonary stenosis, pulmonary insufficiency, aortic stenosis, aortic insufficiency), pulmonary fibrosis, chronic fungal pneumonia, neoplasia, or other infiltrative diseases.