19. Pulmonary - embolism, infarction and hypertension - Cox

• Pulmonary embolism (PE) is due to blood clot that hits pulmonary arteries

  • will obstruct lung blood flow
• PE arises from thrombus that originates from DVT
• How does thrombi goes to PE?

  1. inferior vena cava
  2. R atrium
  3. R ventricle
  4. pulmonary artery
• Massive acute pulmonary embolism - large embolus will saddle R and L pulmonary artery at bifurcation

  • leading to obstructive shock and sudden death
• Massive acute pulmonary embolism is associated with PEA
• PE - antemortem clots display erythrocyte and fibrin layering called lines of Zahn
• PE pathophysiology

  • increased alveolar dead space causing V/Q mismatch
  • there is vascular obstruction so decrease perfusion (Q)
  • hypoxemia will develop due to decrease gas exchange
• PE will lead to SOB with compensatory hyperventilation
• PE occasion can reduce pulmonary vascular bed cross sectional area

  • result in increase pulmonary vascular resistance (parallel resistors)
  • cause increase R ventricular afterload --> right heart strain
  • will lead to lack of blood to LV - which will defect filling
  • reducing CO ---> hypotension
• PE classic presentation

  • pleuritic chest pain (pain with breathing)
  • dyspnea
  • hypoxemia
  • hemoptysis
• PE diagnosis

  • increase d-dimer
  • gold standard - CT pulmonary angiography
• PE - wells criteria

  • HR > 100
  • immobile
  • hemoptysis
• Chronic thromboembolic pulmonary HTN - there will be a persisting clot due to fibrinolysis failure
• Chronic thromboembolic pulmonary HTN - characterized by intraluminal thrombus organization

  • causing fibrous stenosis or complete obliteration of pulmonary arteries
• Chronic thromboembolic pulmonary HTN may result in?

  • elevated pulmonary artery pressure
  • inducing vascular remodeling --> cor pulmonale
• Pulmonary Infarction is due to PE resulting in tissue necrosis
• Pulmonary infarction is not common because?

  there is 2 vascular system - pulmonary and bronchial system
• Pulmonary Infarction - embolus will obstruct pulmonary system leading to bronchial arteries becoming primary perfusion source

  • leading to
  • increase bronchial arterial pressure
  • locally increase vascular permeability
  • capillary injury
• Pulmonary Infarction will lead to local pulmonary capillary hemorrhage die to increase bronchial arterial pressure
• Pulmonary Infarct occurs in certain circumstances:

  • decrease bronchial artery flow
  • increase pulmonary venous pressure
• pulmonary infarction

  • initial presentation
  • hemorrhagic due to bronchial artery extravasation
  • Progressive
  • failure to re-establish perfusion within 48 hrs will lead to true infarction
  • leading to necrosis
• Pulmonary Arterial Hypertension (PAH) defined as

  • mean pulmonary arterial pressure
  • (at rest) - > 25 mmHg
  • (exercise) - > 30 mmHg
• Pulmonary Arterial Hypertension (PAH) characterized by sustained and progressive pulmonary vascular resistance
• the most common cause of pulmonary hypertension?

  group 2 - due to left sided heart disease
• Pulmonary hypertension involve

  • vasoconstriction
  • remodeling
  • thrombosis
• 4 main remodeling components of hypertension

  • muscular hypertrophy
  • intimal thickening
  • adventitial thickening
  • plexiform lesion