Exam 4 - Pulmonary Hypertension Flashcards
what is pulmonary hypertension?
elevated blood pressure in the pulmonary arteries
systemic pulmonary artery pressure greater than 25 mmHg (normal is under 25/8)
what is the clinical significance of pulmonary hypertension?
sequelae of common diseases in the dog - contributes to patient morbidity & mortality
what are the five groups of pulmonary hypertension?
- pulmonary arterial hypertension
- pulmonary hypertension caused by left sided heart disease
- pulmonary hypertension caused by lung disease/chronic hypoxia
- pulmonary hypertension caused by chronic blood clots - pulmonary thromboembolism
- pulmonary hypertension related to unclear or multifactorial mechanisms
what is an example of a disease process that falls under pulmonary arterial hypertension?
increase in pulmonary blood flow
congenital left to right shunts - PDA, VSD, or ASD
what is the pathophysiology of congenital left to right shunts?
- extra blood volume in the lungs leads to vasoconstriction of the pulmonary arteries causing an increase in pressure
- overcirculation in the lungs leads to vasoconstriction of pulmonary arteries/arterioles
what is the most common sequelae of a left to right shunt?
left sided CHF resulting in cardiogenic pulmonary edema
T/F: most reverse PDAs were born with pulmonary arterial hypertension & never shunted left to right
true
what is an example of a disease process that falls under pulmonary hypertension caused by chronic left-sided heart disease?
chronic valvular disease
what is the pathophysiology of chronic valvular disease causing pulmonary hypertension?
chronic increase in left atrial pressure
- increase in pulmonary venous return
- release of vasoactive cytokines from endothelium
- vasoconstriction of pulmonary arteries & vascular smooth muscle hypertrophy causing remodeling/thickening of the heart
- increase in pulmonary arterial pressure
why is pulmonary venous hypertension clinically significant?
it is 40% of the etiology of hypertension in dogs
CVD is 70% the etiology of PVH in the dog
what clinical signs are associated with pulmonary venous hypertension secondary to cvd in dogs? what is the mortality?
cough, dyspnea, exercise intolerance, syncope with excitement, & right heart failure
moderate to severe pulmonary hypertension in dogs with CVD is associated with a poor prognosis - decrease in survival & increase in morbidity
what are some examples of disease processes that fall pulmonary hypertension caused by lung disease/chronic hypoxia?
chronic bronchitis, collapsing trachea, brachycephalic syndrome, pneumonia, pulmonary neoplasia, etc
what is the pathophysiology of pulmonary hypertension caused by lung disease/chronic hypoxia?
decreased oxygen delivery to the lungs
- pulmonary arteries constrict to reroute blood to areas that are better ventilated
- increase in pulmonary arterial resistance
- increase in pulmonary arterial pressure
what are some examples of disease processes caused by pulmonary thromboembolism resulting in pulmonary hypertension?
diseases that cause pro-coagulation
PLN, PLE, cushings, high dose corticosteroids, vasculitis, & paraneoplastic syndrome
what are some examples of disease processes that cause pulmonary hypertension that is related to unclear or multifactorial mechanisms?
masses pressing against pulmonary arteries & heartworm disease
what are the most common groups of disease that cause pulmonary hypertension in the dog?
increased pulmonary venous pressure (group 2 ) & increased pulmonary arterial resistance through lung disease/hypoxia
what are some identified triggers of pulmonary hypertension?
hypoxia, pulmonary venous hypertension, inflammation, & PTE
what are the general overall mechanisms that result from identified triggers causing pulmonary hypertension?
dysregulation of pulmonary vasomotor tone - vasoconstriction - increased pulmonary pressure
increased cell proliferation & decreased apoptosis in small pulmonary arteries - pulmonary vascular thickening - increased pulmonary pressure
thrombosis in situ - increased pulmonary resistance - increased pulmonary pressure
what is the common clinical presentation of pulmonary hypertension?
right sided heart failure - ascites, +/- pleural effusion, jugular distension, hepatomegaly
syncope/weakness, respiratory distress, sudden death
what is the treatment of pulmonary hypertension? what are the goals?
there is no cure
goals - palliate clinical signs & prolong survival
what are some examples of pulmonary hypertension etiology dependent therapy?
left-sided heart failure - lasix, pimobendan, ACEi
chronic airway therapy - abx, bronchodilators, cough suppressants
PTE therapy - aspirin, clopidogrel
HW therapy - prednisone, adulticide, doxycycline
right-sided heart failure - abdominocentesis, lasix, furosemide
intermittent oxygen & high altitude avoidance
what is sildenafil used for in pulmonary hypertension??
phosphodiesterase V inhibitor - pulmonary vasodilator
what is pimobendan used for in pulmonary hypertension?
used in dogs with CVD & right-sided CHF
predominantly PDE III inhibitor & calcium sensitization
what are the 3 components of virchow’s triad?
- endothelial damage
- hypercoagulability
- abnormal/stasis of blood flow
what is the mechanism of action of sildenafil?
inhibition of PDE V which is responsible for the degradation of cGMP - so it increases cGMP causing nitric oxide mediated vasodilation within the pulmonary vasculature - vascular smooth muscle relaxation
what is needed for a diagnosis of pulmonary hypertension?
clinical signs & rads
major signs on echo - high estimate of RV systolic pressure & pulmonary artery diastolic pressure
minor signs on echo - right heart chamber enlargement, septal flattening in systole
what are some clinical signs that should lead your suspicion towards pulmonary hypertension?
patient presenting for syncope, diagnosed associated syndromes (chronic respiratory disease, CVD, young dog with pneumonia)
right-sided congestive heart failure, right-sided heart enlargement
what are the therapeutic goals in symptomatic patients with pulmonary hypertension?
palliate clinical signs of right-sided heart failure/left-sided heart failure in dogs with CVD
investigate possible causes & treat if possible
initiate sildenafil, +/- l-arginine, +/- fish-oil, +/- anti-platelet therapy
what are the therapeutic goals in asymptomatic patients with pulmonary hypertension?
investigate & treat etiologic causes
surveillance of mild pulmonary hypertension
consider therapy in moderate to severe pulmonary hypertension
