Pulmonary hypertension Flashcards
What are the 3 sites used for echocardiographic assessment of the probability of pulmonary hypertension. Give some examples of signs of PH.
- Ventricles
- flattening of inter ventricular septum
- underfilled left ventricle
- right ventricular hypertrophy (thickening and/or dilation)
- right ventricular systolic dysfunction - Pulmonary artery
- PA/Ao > 1.0
- peak early diastolic pulmonary regurgitation >2.5 m/s
- right pulmonary artery distensibility index <30%
- RV Doppler outflow acceleration time <52-58ms or systolic notching - Right atrium and caudal vena cava
- RA enlargement
- CVC enlargement
When tricuspid regurgitation cannot be measured, how many sites of echocardiography must have signs of pulmonary hypertension to conclude to a high probability of PH
3 sites
(2 sites if TR 3.0-3.4 m/s and 1 site if TR > 3.4 m/s)
What are the 6 groups of pulmonary hypertension classification? Give 1 example of cause for each
- Pulmonary arterial hypertension (ex: congenital cardiac shunts)
- PH due to left heart disease (ex: MMVD)
- PH due to respiratory disease / hypoxia (ex: fibrotic lung disease)
- Pulmonary embolism / thrombosis / thromboembolism (ex: acute PTE)
- Parasitic disease (ex: Dirofilaria)
- Multifactorial / unclear (ex: mass compressing the pulmonary artery)
What can cardiac auscultation reveal in a dog with pulmonary hypertension
- Tricuspid systolic heart murmur
- Diastolic pulmonic heart murmur
- Split S2
- (Mitral murmur if secondary to left heart disease)
What are radiographic signs of pulmonary hypertension
- Dilated / tortuous pulmonary arteries
- Patchy, diffuse alveolar infiltrates
- Bulge in the region of the pulmonary trunk
- Right-sided cardiac enlargement
What is the mechanism of action of sildenafil
Phosphodiesterase-5 inhibitor -> inhibits cGMP catabolism -> increases cGMP -> increases NO in pulmonary vasculature -> vasodilation -> decrease in pulmonary vascular resistance + prevention of smooth muscle cell hypertrophy
What is a possible complication of sildenafil? What groups (causes) of PH are more at risk?
Acute pulmonary edema
Dogs with PH without increased pulmonary vascular resistance are more at risk (PH due to left heart disease, left-to-right shunt, pulmonary veno-occlusive disease, )
Is sildenafil indicated in dogs with pulmonary hypertension caused by intracardiac shunt
Only if the shunt is right-to-left - and direction of the shunt should be reassessed after initiating sildenafil (if switched to left-to-right the shunt should be closed)
Name 3 causes of pulmonary hypertension for which sildenafil is indicated and 3 for which it is not indicated
Indicated:
- PH secondary to chronic pulmonary disease / hypoxia
- Group 1 a-c (idiopathic, hereditary, drugs/toxin induced)
- PH secondary to chronic PTE (+/- acute massive PTE)
Not indicated:
- PH secondary to left heart disease
- PH secondary to veno-occlusive disease
- PH secondary to left-to-right shunt
What is the tricuspid regurgitation velocity threshold for clinical definition of pulmonary hypertension
3.4 m/s (= 46 mmHg)
Name 2 potential alternative therapies for pulmonary hypertension
- Milrinone (PDE3 inhibitor)
- L-arginine (NO precursor)
What are the 3 major mechanisms leading to pulmonary hypertension
- “Post-capillary” pulmonary hypertension = pulmonary venous hypertension: chronic increase in pulmonary venous pressure from left heart failure or mass compressing large pulmonary vein
- “Pre-capillary” pulmonary hypertension = increased pulmonary vascular resistance (from vasoconstriction / remodelling / thrombosis)
- Increased pulmonary blood flow = left-to-right shunt
Name 3 clinical signs strongly suggestive of pulmonary hypertension and 3 clinical signs possibly suggestive
- Strongly suggestive:
- Syncope
- Respiratory distress at rest
- Exercise terminating in respiratory distress
- Right heart failure - Possibly suggestive:
- Tachypnea at rest
- Increased respiratory effort at rest
- Prolonged post-exercise tachypnea
