Pulmonary Hypertension: Pathogenesis and Clinical Findings
Left heart disease (heart failure, myocardial infarction)
↓ contractility and/or diastolic relaxation
↓ left ventricle cardiac output Backup of blood in left ventricle and atrium Backup of blood in pulmonary vasculature
↑ pulmonary capillary wedge pressure– estimate of blood pressure in left atrium
Chronic Anemia
↓ plasma hemoglobin content
↓ oxygen carrying capacity per unit blood
Compensatory ↑ in heart rate to maintain tissue oxygen supply
↑ cardiac output
Lung disease (chronic obstructive pulmonary disease)
Tissue breakdown and ↓ lung elasticity
Chronic thromboembolism
Pulmonary vessel disease (pulmonary arterial hypertension, scleroderma)
Vascular obstruction/fibrosis
↓ lungs’ ventilation ability
↓ surface areaà↓ gas exchange
Lung vasculature undergo reflexive, localized vaso- constriction, to shunt blood to better ventilated areas
Chronic hypoxemia
↓ local alveolar partial pressure of oxygen
↓ blood vessel compliance
↑ Pulmonary vascular resistance (PVR)
Impaired gas exchange across thickened vessel walls
↓ blood partial pressure of O2 and ↑ partial pressure of CO2
Insufficient O2 provision & CO2 removal from tissues
Reflexive mechanisms trigger harder & faster breathing to compensate
Vascular fibrosis due to chronically increased pressures
↓ circulation of blood to left heart and ↓ filling of left ventricle
↓ left ventricle cardiac output
Elevated blood pressure in the lung arteries Pulmonary Hypertension
↑ right-ventricle afterload (pressure against which the heart contracts to eject blood)
↓ right ventricle cardiac output
↑ residual volume in right heart after cardiac contraction
Backup of blood in systemic circulation ↑ blood volume in venous system
Myocardial hypertrophy develops over time (eccentric & concentric)
↑ tissue volume
↑ myocardial oxygen demand
Myocardial ischemia (supply/demand mismatch)
↑ risk of chest pain in times of ↑ oxygen demand
Peripheral edema
Formation of aberrant conduction pathways and ectopic electrical foci
Dysrhythmias
Palpitations
↓ tissue perfusion
Fatigue
Dyspnea
↓ brain perfusion
Syncope
Authors: Grant E. MacKinnon Davis Maclean Hannah Yaphe Reviewers: Yan Yu* Jason Weatherald* * MD at time of publication
↑ volume and blood pressure in capillaries Fluid pushed from vessels into interstitial space of tissues
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published September 8, 2020 on www.thecalgaryguide.com