Exam 4 - Pulmonary Hypertension

Question 1

what is pulmonary hypertension?

Answer 1

elevated blood pressure in the pulmonary arteries

systemic pulmonary artery pressure greater than 25 mmHg (normal is under 25/8)

Question 2

what is the clinical significance of pulmonary hypertension?

Answer 2

sequelae of common diseases in the dog - contributes to patient morbidity & mortality

Question 3

what are the five groups of pulmonary hypertension?

Answer 3

1. pulmonary arterial hypertension
2. pulmonary hypertension caused by left sided heart disease
3. pulmonary hypertension caused by lung disease/chronic hypoxia
4. pulmonary hypertension caused by chronic blood clots - pulmonary thromboembolism
5. pulmonary hypertension related to unclear or multifactorial mechanisms

Question 4

what is an example of a disease process that falls under pulmonary arterial hypertension?

Answer 4

increase in pulmonary blood flow

congenital left to right shunts - PDA, VSD, or ASD

Question 5

what is the pathophysiology of congenital left to right shunts?

Answer 5

1. extra blood volume in the lungs leads to vasoconstriction of the pulmonary arteries causing an increase in pressure
2. overcirculation in the lungs leads to vasoconstriction of pulmonary arteries/arterioles

Question 6

what is the most common sequelae of a left to right shunt?

Answer 6

left sided CHF resulting in cardiogenic pulmonary edema

Question 7

T/F: most reverse PDAs were born with pulmonary arterial hypertension & never shunted left to right

Answer 7

true

Question 8

what is an example of a disease process that falls under pulmonary hypertension caused by chronic left-sided heart disease?

Answer 8

chronic valvular disease

Question 9

what is the pathophysiology of chronic valvular disease causing pulmonary hypertension?

Answer 9

chronic increase in left atrial pressure

1. increase in pulmonary venous return
2. release of vasoactive cytokines from endothelium
3. vasoconstriction of pulmonary arteries & vascular smooth muscle hypertrophy causing remodeling/thickening of the heart
4. increase in pulmonary arterial pressure

Question 10

why is pulmonary venous hypertension clinically significant?

Answer 10

it is 40% of the etiology of hypertension in dogs

CVD is 70% the etiology of PVH in the dog

Question 11

what clinical signs are associated with pulmonary venous hypertension secondary to cvd in dogs? what is the mortality?

Answer 11

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

Question 12

what are some examples of disease processes that fall pulmonary hypertension caused by lung disease/chronic hypoxia?

Answer 12

chronic bronchitis, collapsing trachea, brachycephalic syndrome, pneumonia, pulmonary neoplasia, etc

Question 13

what is the pathophysiology of pulmonary hypertension caused by lung disease/chronic hypoxia?

Answer 13

decreased oxygen delivery to the lungs

1. pulmonary arteries constrict to reroute blood to areas that are better ventilated
2. increase in pulmonary arterial resistance
3. increase in pulmonary arterial pressure

Question 14

what are some examples of disease processes caused by pulmonary thromboembolism resulting in pulmonary hypertension?

Answer 14

diseases that cause pro-coagulation

PLN, PLE, cushings, high dose corticosteroids, vasculitis, & paraneoplastic syndrome

Question 15

what are some examples of disease processes that cause pulmonary hypertension that is related to unclear or multifactorial mechanisms?

Answer 15

masses pressing against pulmonary arteries & heartworm disease

Question 16

what are the most common groups of disease that cause pulmonary hypertension in the dog?

Answer 16

increased pulmonary venous pressure (group 2 ) & increased pulmonary arterial resistance through lung disease/hypoxia

Question 17

what are some identified triggers of pulmonary hypertension?

Answer 17

hypoxia, pulmonary venous hypertension, inflammation, & PTE

Question 18

what are the general overall mechanisms that result from identified triggers causing pulmonary hypertension?

Answer 18

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

Question 19

what is the common clinical presentation of pulmonary hypertension?

Answer 19

right sided heart failure - ascites, +/- pleural effusion, jugular distension, hepatomegaly

syncope/weakness, respiratory distress, sudden death

Question 20

what is the treatment of pulmonary hypertension? what are the goals?

Answer 20

there is no cure

goals - palliate clinical signs & prolong survival

Question 21

what are some examples of pulmonary hypertension etiology dependent therapy?

Answer 21

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

Question 22

what is sildenafil used for in pulmonary hypertension??

Answer 22

phosphodiesterase V inhibitor - pulmonary vasodilator

Question 23

what is pimobendan used for in pulmonary hypertension?

Answer 23

used in dogs with CVD & right-sided CHF

predominantly PDE III inhibitor & calcium sensitization

Question 24

what are the 3 components of virchow’s triad?

Answer 24

1. endothelial damage
2. hypercoagulability
3. abnormal/stasis of blood flow

Question 25

what is the mechanism of action of sildenafil?

Answer 25

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

Question 26

what is needed for a diagnosis of pulmonary hypertension?

Answer 26

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

Question 27

what are some clinical signs that should lead your suspicion towards pulmonary hypertension?

Answer 27

patient presenting for syncope, diagnosed associated syndromes (chronic respiratory disease, CVD, young dog with pneumonia)

right-sided congestive heart failure, right-sided heart enlargement

Question 28

what are the therapeutic goals in symptomatic patients with pulmonary hypertension?

Answer 28

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

Question 29

what are the therapeutic goals in asymptomatic patients with pulmonary hypertension?

Answer 29

investigate & treat etiologic causes

surveillance of mild pulmonary hypertension

consider therapy in moderate to severe pulmonary hypertension