Pulmonary hypertension

Background

*Pulmonary Hypertension (PH) = mean PA pressure >25mmHg assessed by right heart cath

• PH divided into 5 groups:
  • Group 1 PAH: Idiopathic pulmonary arterial hypertension, formerly called primary PH
  • Group 2 PH: PH due to left heart disease (systolic/diastolic dysfunction and valvular heart dz)
  • Group 3 PH: PH due to lung diseases or various causes of hypoxemia, such as COPD, ILD, or sleep-disordered breathing
  • Group 4 PH: PH due to chronic thromboembolic disease
  • Group 5 PH: PH of unclear multifactorial mechanisms (myeloproliferative dz, sarcoidosis, glycogen storage dz, etc)

Etiology

• PAH can be heritable, idiopathic, or associated with connective tissue disease, HIV, portal HTN, congenital heart dz, schistosomiasis, chronic hemolytic anemia
• PH can be due to lung disease, left heart disease, chronic exposure to high altitudes, chronic thromboembolic disease, myeloproliferative disorders, sarcoidosis, vasculitis, glycogen storage disease, Gaucher disease, chronic renal failure on dialysis

Diagnosis

• Physical exam:
  • Consider in undifferentiated patients with dyspnea, fatigue, syncope (late PH finding), chest pain, palpitations, LE edema
  • Look for JVD, hepatomegaly, ascites, edema, stigmata of liver failure
• ECG findings (similar to acute pulmonary embolism):
  • Right axis deviation
  • Evidence of right heart strain
  • S1Q3T3
  • Right ventricular hypertrophy
    • Large R waves in precordial leads
  • Tachyarrhythmias (aflutter or afib)
• Radiologic findings:
  • CXR:
    • RA enlargement (obliteration of retrosternal space on lateral CXR)
    • Prominent pulmonary vasculature (congestion)
    • PA dilation
  • CT Chest:
    • Pulmonary artery > ascending aorta suggests PH
    • Pulmonary artery diameter greater than 30 mm suggest PH
    • Right heart enlargement
  • Echocardiogram:
    • RV close to LV size (+/- septal bowing)
    • RVH

Chronic Therapies

Prostacyclins

Mechanisms of action: vasodilatation, inhibit platelet aggregation

• Epoprostenol, Iloprost, Treprostinil, Beraprost
  • Complications include acute decompensation if stopped abruptly, diarrhea, edema, headache

Phosphodiesterase Type 5 (PDE5) Inhibitors

Mechanism of Action: vasodilation, increases RV contractility

• Sildenafil
• Complications include hypotension with administration of nitrates, flushing, epistaxis, headache

Endothelin receptor antagonists

Mechanism of Action: vasodilation via vascular modulation modulation

• Bosentan, Ambrisentan
  • Complications include liver failure, supratherapeutic INR,
• Patients also usually taking digoxin, coumadin, diuretics, home O2. RARELY are they on CCB only if responsive during cath. Consider line infections as complication to chronic infusions.

Acute Treatment for PAH crisis

1. Decrease preload - no fluids, consider diuretics
2. O2
3. Optimize myocardial contractility
   1. Treat relative bradycardia
      1. atropine, pace, low dose dobutamine <5mcg/kg/min to increase contractility
      2. Consider norepinephrine prior to dobutamine if hypotensive
   2. Rhythm control for tachycardias - NO CCB or BB for rate control
      1. Electrical cardioversion or amiodarone
4. Decrease afterload - pulmonary vasodilation
   1. sildenafil, bostantan, epoprostenol (2ng/kg/min), inhaled NO if intubated
5. Check INR, dig level and correct
6. Empiric abx
7. If intubated, low PEEP, low tidal volumes

Source

• 4/07 DONALDSON (adapted from Sarver)
• Critical Decisions in Emergency Medicine, May 2013; 27(5)