Pulmonary hypertension

Background

  • Mean PA pressure >25 mmHg as assessed by right heart catheterization
    • Since right ventricle is dependent on preload, RV contractility and afterload, severe pulmonary arterial hypertension causes pathological changes to right ventricle

WHO Classification[1]

Etiologies

  • Heritable
  • Idiopathic
  • Chronic hypoxia
  • Chronic thromboembolic disease
  • Vasculitis
  • Autoimmune disease
  • Toxic exposures
  • Vasculitis
  • Chronic renal failure on dialysis
  • Myeloproliferative disorders

Clinical Features

History

Physical exam

  • JVD
  • Hepatomegaly
  • Ascites
  • Edema
  • Stigmata of liver failure

Differential Diagnosis

Acute dyspnea

Emergent

Non-Emergent

Evaluation

Some, all or none of the following findings may be present.

  • BNP: Elevated[2]
  • ECG findings (similar to acute pulmonary embolism):
    • Right axis deviation
    • Evidence of right heart strain on bedside ultrasound or CT
    • S1Q3T3 ECG finding
    • Twave inversions on ECG in inferior and anteroseptal leads
    • Right ventricular hypertrophy
  • Large R waves in precordial leads
  • Tachyarrhythmias (atrial flutter or atrial fibrillation if new portend poorer prognosis)[3]

CXR Abnormalities

    • RA enlargement (obliteration of retrosternal space on lateral CXR)
    • Prominent pulmonary vasculature (congestion)
    • PA dilation

CTA Chest Abnormalities

  • Pulmonary artery > ascending aorta suggests PH
  • Pulmonary artery diameter greater than 30 mm suggest PH
  • Right heart enlargement

Echocardiographic Findings

  • D sign (McConnel's Sign)
  • RV close to LV size (+/- septal flattening/bowing)
  • Tricuspid valve regurgitation
  • Estimate systolic pulmonary artery pressure (SPAP) with echo[4]
    • SPAP = Max TR gradient + Mean RAP
    • Cannot use this method with vent-dependent patients, pulmonic stenosis
    • Max TR gradient as measured by tricuspid regurgitation (TR) jet, which >90% of adults have
    • Use parallel CW Doppler line across TR jet in apical view
    • Obtain dense TR profile below the line with well-defined envelope and measure peak = Max TR gradient
    • Estimate right atrial pressure (RAP) with IVC diameter from subcostal view
Normal Intermediate High
Mean RAP, mmHg 3 8 15
IVC diameter max 2.1 max 2.1 > 2.1
Resp variation >50% <50% <50%

Evaluation

  • Initial diagnosis not typically made in the ED because right-sided heart catheterization needed for definitive diagnosis[2]

Acute Management

PH patients do not tolerate rapid changes in hemodynamics well, all therapies should be instituted with caution. Do NOT rate control tachycardias, best to electrically cardiovert or attempt rhythm control with amiodarone

Optimize Circulation

  1. Optimize (usually reduce) RV preload:
    • Usually euvolemic or hypervolemic, rarely need IV fluids so diuretics can benefit and treat the RV failure[5]
      • Furosemide 20-40mg IV
      • Furosemide drip at 5-20mg/hr
    • If suspect sepsis or hypovolemia, small (250-500cc) NS challenge to assess fluid responsiveness. If not responsive to IVF challenge, start norepinephrine (MAP > 65 mmHg).
  2. Increase cardiac output:
    • Once MAP >65 mmHg, start low dose dobutamine (5-10mcg/kg/min)
    • Improves inotropic support and theoretically decreases pulmonary vascular resistance
  3. Reduce RV afterload:
    • Avoid hypoxia, maintain O2 sat >90% (increases pulmonary vasoconstriction)
    • Avoid hypercapnea (increases pulmonary vascular resistance)
    • Avoid acidosis
  4. Treat arrhythmias:
    • SVT most common although may also become bradycardic (aflutter and afib occur equally)
    • Treatment of aflutter is often more successful than afib
    • Do not tolerate negative inotropy, deteriorate to RV failure
  • May require radiofrequency ablation
  • AVOID calcium channel blockers or β-blockers

Optimize Oxygenation

  • Intubated patients should be optimized to increased O2 delivery and minimize hypercapnea, maintain low tidal volumes and low PEEP as tolerated

Early Consultation[2]

  • May require interventions not readily available in the ED:
    • Pulmonary arterial catheter
    • Inhaled plumonary vasodilators
    • Mechanical support with right ventricular assist device or ECMO

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.

Disposition

  • Low threshold for admission if acute decompensation

See Also

References

  1. Ryan, J. et al. (2012) The WHO classification of pulmonary hypertension: A case-based imaging compendium. Pulmonary Circulation, 2(1).
  2. 2.0 2.1 2.2 2.3 Wilcox et al. "Pulmonary Hypertension and Right Ventricular Failure in Emergency Medicine." Annals of EM. Dec 2015. 66(6):619-631
  3. Geibel A et al. Prognostic value of the ECG on admission in patients with acute major pulmonary embolism. European Respiratory Journal. 2005. 25: 843-848
  4. Critical USG. Echocardiographic assessment of pulmonary artery pressure. 2012. http://www.criticalusg.pl/en/echo/tte/tutorials/echocardiographic-assessment-of-pulmonary-artery-pressures
  5. Ternacle, J et al. Diruetics in Normotensive Patients with Acute Pulmonary Embolism and Right Ventricular Dilation. Circulation Journal. Vol 77(10) 2013. 2612-618.

Authors:

Ross Donaldson