Pulmonary Hypertension Flashcards
Pulmonary hypertension PA pressure?
Dogs or cats at sea level systolic PA greater than 30 mmHg, mean PA pressure greater than 20, and diastolic pressure greater than 15.
Five clinical categories of PH?
1st category?
1.Pulmonary arterial hypertension: idiopathic PAH, familial (not documented vet med). Also number of conditions that have lesion localization to precapillary segments of pulmonary vasculature (heartworm, certain drug/toxin exp, congential systemic to pulmonary shunts?
2nd category of PH?
PH secondary to left heart disease. Myocardial or valvular. PH results from high left atrial pressure and pulmonary venous pressures. Tx: unloading agents (systemic vasodilators), improve myocardial performance. Then consider PA dilators.
3rd category PH?
Disorders of lungs or hypoxemia. Ex: interstitial lung disease, COPD, chronic exposure to high altitudes.
4th category PH?
Thrombotic or embolic disease. Heartworm, embolization of pulmonary arteries also occurs with thrombi, neoplasia, other parasites, foreign material.
5th category PH?
Miscellaneous disorders - conditions causing compression of pulmonary vessels. Neoplasia, lymphadenopathy, fibrosing mediastinitis, granulomatous disease.
Heart murmur of severe PH?
Tricuspid regurgitant murmur intensity increases, often palpable precordial thrill. A split S2 heart sound may be heard, associated with delayed closure of PV relative to AV.
Characteristic ECG findings of PH?
Occur with severe disease. Right axis shift, p-pulmonale, sometimes APCs and a Fib.
Obtaining PH reading from echo?
Tendency of tricuspid valve and PVs to leak with high PA pressures. Since pressure across open valve same (except stenosis), the RV systolic and PA systolic pressure are equal. Measurement of TV or PV regurgitant max velocity. Pressure estimated with modified bernoulli equation. 4 xV^2=pressure
Changes seen on Echo?
Changes in RV structure and function. Hypertrophy and dilation of right ventricle. Flattening of septum as RV pressures exceed LV.
Examples of vasodilators?
Prostanoids (exogenous prostaglandin analogue). Prostacyclin is vasodilator (pulmonary and systemic). Expensive, short half-life, method of adminstration - impractical in vet med.
Endothelin receptor antagonist - bosentan. Endothelian 1 overexpressed in several forms of pulmonary vasculature dz. Expensive.
PDE-5inhibitors-sidenafil. PDE inactivate CAMP and CGMP (2nd messengers of prostacyclin). Expensive.
Prognosis for PH?
Variable, depends on ability to manage underlying condition. Favorable prognosis (> year) for Category 2. R-L shunts and congenital heart defects (4 to 5 years). Poor prognosis for lung disease or thromboembolic disease.
Examples of endothelium derived relaxing factors?
NO, prostacyclin
Example of endothellium derived constriction factors?
endothelin-1, thromboxane, serotonin
