Physiology Flashcards
Pulmonary Hypertension
an elevation of pulmonary vascular pressure caused by an isolated increase in pulmonary arterial pressure or by increase in both pulmonary arterial and pulmonary venous pressure
Pulmonary Arterial Hypertension
characterized by a sustained elevation of mean pulmonary arterial pressure (mPAP) to > 25 mmHg at rest, with normal pulmonary capillary wedge pressure (left capillary pressure–> estimated the preload on the left side) and left ventricular end-diastolic pressure (
What is the difference between PH and PAH?
Pulmonary hypertension (PH) simply refers to elevation of BP in your lungs. Pulmonary arterial hypertension (PAH) is a sub-group of PH caused by narrowing of the blood vessels in the lungs. Most PH is not PAH, and in these cases, PH is usually result of other diseases
what are the main vascular changes of PAH?
vasoconstriction
smooth muscle cell and endothelial cell proliferation
fibrosis
thrombosis
– severe concentric (equal on all sides) laminar intimal fibrosis
– medial hypertrophy
– in situ thrombosis of small residual lumen
Physical Presentation symptoms
extertional dyspnea (right side of the heart not equipped to over come high pressures)
fatigue
weakness
exertional chest pain (heart trying to work harder and needs additional blood flow and oxygen)
complaints of general exertion intolerance
dyspnea at rest as disease progresses
syncope (fainting due to changes in vascular resistance)
lower extremity edema (backup to the left = lungs, right = periphery)
Idiopathic (40%) Heritable PAH
BMPR2 gene 70-75% of people (+) polymirphism
ALK1 gene
Drug and toxin-induced PAH
Aminorex Dexfenfluramine Fenfluramine Amphetamines L-Tryptophan Methamphetamines Chemotherapeutic agents Cocaine Phenylpropanolamine Selective serotonin reuptake inhibitor (fetus more affected than the mother)
Conditions associated with PAH
Chronic Hemolytic anemia Congenital heart disease Connective tissue disease Human immunodeficiency virus infection Portal hypertension Schistosomiasis Persisten pulmonary hypertension of the newborn
Prostacyclin Drug target
- vasodilator
- inhibits platelet activation
- antiproliferative properties
- by product of arachidonic pathway
Thromboxane A2 Drug target
- vasoconstrictor
- platelet agonist
Endothelin-1 drug target
= potent vasoconstrictor
- stimulates proliferation of smooth muscle cells
- plasma levels increased in PHT
- level inversely proportional to pulmonary blood flow & CO
- ETa= vascular smooth muscle
- ETb= on endothelium
NO & Serotonin drug target
NO: vasodilator & inhibitor of platelet activation & vascular SM proliferation. NO–>cGMP–> decrease Ca–> smooth muscle relaxation of smooth muscle cells
Serotonin: vasoconstrictor promoting SM hyperplasia & hypertrophy
Non-selective ETa/ETb endothelin receptor antagonist
Bosentan (Tracleer)
Macitentan (Opsumit)
MOA: block endothelin-1 and endothelin-2 receptors in the vascular smooth muscle
Selective ETa endothelin receptor antagonist
Ambrisentan (Letairis)
- at extremely high doses it becomes non-selective
MOA: block/selectively block endothelin-1 receptors in the vascular smooth muscle.
–> improve pulmonary hemodynamics, exercise capacity, functional status, & clinical outsomes
Adverse Effects of Endothelin receptor antagonist
Most common: peripheral edema, nasal congestion, sinusitis, flushing (all have to deal w/some type of vasoconstriction)
Additional side effects: elevated liver enzymes (upset stomach, vomiting, fever, stomach pain)
BLACK BOX WARNING: Pregnancy category X
Prostanoids
Epoprostenol (Flolan)
Ilopost (Ventavis)
Treprostinil- synthetic analog of prostacyclin
IV or SC: Remodulin
Inhaled: Tyvasco
PO: Orentitram
MOA: agonist at the prostacyclin EP receptor producing potent vasodilatory activity and inhibition of platelet aggregation
Side effects of Prostanoids
flushing, headache, chest pain, skeletal pain, diarrhea, abrupt interruption of treatment can lead to worsening in PAH
Nitric Oxide
MOA: stimulates soluble guanylyl cyclase, resulting in increased levels of cyclic GMP in lung smooth muscle cells producing vasodilation
Adverse effects of Nitric oxide
Headache, hypotension
Phosphodiesterase Inhibitors
Sildenafil (Revatio)
Tadalafil (Adcirca)
MOA: inhibition of PDE5, the predominant PDE isoform in the lung that metabolizes cGMP
Phosphodiesterase inhibitors cross reactivity
PDE6 activity (retinal enzyme)--> vision abberations PDE1 activity (vascular/cardiac enzyme)--> flushing, tachycardia, vasodilation PDE11 activity (skeletal muscle)
Adverse Drug reactions of PDE inhibitors
Sildenafil Tadalafil
HA 4% 11%
Flushing 1% 6%
Dyspepsia 2% 4%
Nasal Cong 2% 4%
Other (blue hue) (back pain,
myalgia,
pain limbs & caution
w/hepatic dysfunction)
PDE-5 Inhibitor & NAION
- loss of eyesight following dosing
–> Non-arteritic Anterior Ischemic Optic Neuropathy
Patients at risk are: heart disease, HTN, > 50 yo, High cholesterol, DM, smokers, & eye problems
Soluble Guanylyl Cyclase
Riociguat (Adempas)
MOA: increases sensitivity of soluble guanylyl cyclase to NO and independently activates soluble guanylyl cyclase. Produces ant-platelet and vasodilatory effects.
Adverse side effects of Soluble Guanylyl Cyclase
Headache, GI effects, hypotension, confusion, bleeding, fatigue
