Diseases of Pulmonary Circulation Flashcards
- Explain the relationship between flow, pressure and resistance in the pulmonary vascular bed and describe how changes in theses components can result in increased pulmonary artery pressure.
low pressure, low resistance, high capacitance system (increase in CO results in recruitment and dissension of capillaries rather than a large increase in pressure)
- Identify the broad categories of disease that may result in pulmonary hypertension as reflected in the WHO classification scheme.
- Pulmonary aerial hypertension
- Pulmonary hypertension owing to left heart disease
- Pulmonary hypertension owing to lung disease and/or hypoxia
- Chronic thromboembolic pulmonary hypertension
- Pulmonary hypertension with unclear multifactorial causes
increased LAP (CHF or mitral stenosis) increased PVR (vasoconstriction, obstruction or obliteration) increased CO (L-R shunt)
- Describe the vascular remodeling that occurs in pulmonary hypertension.
normal p. vasculature is a low pressure, low resistance system, forms a relatively passive bed with minimal musculature
remodeling includes: medial hypertrophy muscularization of arterioles intimal proliferation plexogenic pulmonary arteriopathy (plexiform lesions, laminar intimal fibrosis, fibrinoid necrosis, organized thrombus
arterioles and small arteries are most prominently affected with increases in medial muscle thickness and intimal fibrosis
- Explain the concept of hypoxic pulmonary vasoconstriction and its adaptive importance.
alveolar hypoxia: most powerful and most common stimulus (modulated by NO, prostanoids and endothelia’s as well as a direct effect of SM contraction) (feed forward)
whole lung- results in more global redistribution of blood flow- redistributing blood flow cephalic and improving V/Q mismatch (less with life-long altitude)
chronic hypoxia: may eventually result in structural changes in pulmonary vasculature
other factors: acidosis, hypercapnia, humoral modulators
- Analyze the effects of changes in altitude on V/Q matching.
whole lung- results in more global redistribution of blood flow- redistributing blood flow cephalic and improving V/Q mismatch (less with life-long altitude)
- List common physiologic vasoconstrictors and vasodilators.
endothelia’s, thromboxane A2, histamine, serotonin, angiotension II, dopamine
- Define idiopathic pulmonary arterial hypertension and its associated pathophysiology.
advanced, nonspecific vascular changes of chronic hypertension, including plexogenic lesions (some features of collagen vascular disease)
pathophysiology explained by dysfunctional endothelial cells, perhaps due to loss of control of proliferation or cell death or by mutations in angiogenesis (familial disease bone morphogenetic protein receptor 2)
- Describe the physiology and causes behind Eisenmenger syndrome.
development of pulmonary vascular disease from long-standing, high-flow state through the pulmonary circulation from congenital heart disease (ASD, VSD, anomalous pulmonary venous return, trucks arteriosus, PDA– left to right shunting)
physical exam reveals clubbing, cyanosis and less common RHF signs
- Describe the physiology and causes behind cor pulmonale.
heart disease that can be related pathogenically to altered respiratory structure or function, the same that are associated with pulmonary HTN with exception of left sided heart failure and congenital heart disease
can occur acutely with pulmonary embolism, clinical finding— clinical findings include accentuated P2, Rsided S3 gallop, right ventricular heave, JVD, hepatomeagaly, ascites, peripheral edema, pleural/pericardial effusion
- Describe the epidemiology of pulmonary thromboembolic disease.
common, esp of hospitalized patients 7-9% of autopsied patients; 90% of PEs originate form DVT, as many as 50% of DVTs may result in PE
- LIst the risk factors for deep venous thrombosis.
previous venous thromboembolism heart disease (CHF, atrial arrhythmias, mural thrombosis) cancer, esp adenocarcinomas) trauma/ major injury to lower half pregnancy or puerperium estrogens paralysis or immobility obesity increasing age congenital or acquired clotting abnormalities liver disease (paradoxical)
- Describe what happens to clots after they become lodged in the pulmonary vascular bed and correlate their findings to patient symptoms and outcomes.
large emboli lodge in the main pulmonary artery or its major branches or at the bifurcation (saddle embolus) resulting in large blockage of blood flow through the lung
large may cause acute right sided heart failure
smaller may cause hemorrhage (or infarction w/o collateral circulation)
¾ of all infarcts affect lower lobes, +½ multiple lesions, occluded vessel often at the apex of the wedge infarct; pulmonary infarct classically hemorrhage (raised red-blue area that is eventually red-brown)
- Describe the effects of pulmonary embolism on hemodynamics and gas exchange.
PE disturbs both gas exchange and hemodynamics based on reduction in the cross-sectional area of pulmonary vascular bed
gas exchange abnormalities seen with PE include hypoziema and increased dead space, increased a-A CO2 and O@gradient and increased Vd/Vt
patients with PE typically hyperventilate, hypoxema
- Describe the “natural history” of treated and untreated pulmonary embolism.
massive PE: obstructive shock, acute heart failure and death, patients in shock require embolectomy and fibrinolog
- Discuss the diagnosis of deep venous thrombosis and pulmonary embolism including lab tests and imaging studies.
blood-based diagnostic tests are non specific (D-dimer), in hospital setting requires confirmatory imaging
invasive dye studies- venography and pulmonary angiography
B-mode ultrasonography and impedance plethysmography (DVT) and CT angiography (PE)
