Cardiac catheterization is still the gold standard for diagnosing, assessing the severity, and determining the prognosis and response to therapy in pulmonary hypertension. In the cardiac catheterization laboratory, inhaled nitric oxide is administered to determine if the pulmonary vasculature is still reactive or if the obstruction is fixed. It is dangerous to give nifedipine IV as a test because it could lead to a dangerous episode of hypotension. This procedure has been shown to be safe, with no deaths reported in the NIH registry study. In addition, a recent study reported a procedure-related mortality of 0.055%.

• Right heart catheterization allows the determination of:^{[1][2][3][4][5][6]}
  • Presence or absence of pulmonary hypertension, the underlying etiology, and the prognosis.
  • Prognostic markers such as right atrial pressure, cardiac output, and mean pulmonary artery pressure.
  • Pulmonary venous pressures by measuring pulmonary capillary wedge pressure (PCWP).
• Fick’s method is reliable in patients with PAH for the measurement of cardiac output:

• Since end-expiratory intrathoracic pressure most closely correlates with atmospheric pressure, it is important that all right ventricular, pulmonary artery, pulmonary wedge, and left ventricular pressures be measured at end-expiration.

• The causes of pulmonary hypertension can be classified into three categories which are each characterized by different ranges of values recorded by right heart catheterization.
  • Pre-capillary pulmonary Hypertension (involving the pulmonary artery and arterioles)
    • PAH
    • Congenital heart diseases with Eisenmenger syndrome
    • Thromboembolism
  • Capillary pulmonary hypertension
    • Parenchymal lung diseases
  • Post capillary pulmonary hypertension (passive congestion that leads to elevated capillary wedge pressure)
    • Left heart failure
    • Mitral valve diseases
    • Pulmonary veno-occlusive diseases

• Accordingly, the expected results by right heart catheterization are:
  • Precapillary pulmonary hypertension
    • Mean pulmonary artery pressure > 25 mm Hg. In primary pulmonary hypertension the pulmonary artery diastolic pressure is much higher than the pulmonary capillary wedge pressure.
    • Capillary wedge pressure < 15 mm Hg (knowing that the normal PCWP or left ventricular end diastolic pressure (LVEDP) is less than 8 mmHg)
    • Cardiac output: normal
  • Postcapillary pulmonary hypertension
    • Mean Pulmonary artery pressure > 25 mm Hg
    • Capillary wedge pressure > 15 mm Hg. If the pulmonary hypertension is due to left-sided heart failure, and the pulmonary artery diastolic pressure in the pulmonary capillary wedge pressure will be both similarly elevated.
    • Cardiac output: normal or low

<figure-inline><figure-inline></figure-inline></figure-inline> <figure-inline><figure-inline></figure-inline></figure-inline>

Template:WikiDoc Sources