Chapter 59 - Pulmonary Hypertension

Question 1

Pulmonary artery pressure categorizing severity of pulmonary hypertension ?

Answer 1

Pulmonary hypertension is further categorized based on pulmonary artery pressures (PAP) as :

• mild ( < 50 mmHg),
• moderate (51–75 mmHg),
• severe ( > 75 mmHg)

Question 2

What are the main pulmonary vasodilators?

Answer 2

• Nitric oxide (stimulates formation of cGMP and inhibits calcium release)
• Prostaglandin I2 (stimulates formation of cAMP and decreases intracellular calcium stores)

Question 3

What are the main pulmonary vasoconstrictors?

Answer 3

• Alveolar hypoxia
• Endothelin-1
• Thromboxane
• Serotonin
• mPAP

Question 4

Define the 5 classes of pulmonary hypertension (Evian scheme)

Answer 4

• Class I pulmonary arterial hypertension (HW disease, congenital shunts)
• Class 2 PH due to left-sided heart disease (cardiac valve disease)
• Class 3 PH due to pulmonary disease (tracheal collapse, chronic bronchitis, interstitial fibrosis)
• Class 4 PH due to thromboembolic disease
• Class 5 PH due to unclear or multifactorial mechanisms (chronic IMHA, myeloproliferative disorders, obstructive tumors and granulomatous disease)

Question 5

What is the test used to diagnose Eisenmenger’s syndrome?

Answer 5

A bubble study is often needed to document blood flow from the right side of the heart to the left

Question 6

Give the modified Bernouilli equation used to determine the pulmonary hypertension if a tricuspid regurgitation is present

Answer 6

Pressure gradient (mmHG) = maximum TR velocity (m/s)2 × 4

Question 7

What is the mechanism of action of sildenafil?

Answer 7

Sildenafil is a phosphodiesterase 5 inhibitor. Phosphodiesterase 5 (PDE-5) is highly concentrated in pulmonary vessels, and leads to the breakdown of cGMP. Inhibition of PDE-5 results in higher concentrations of cGMP, therefore decreased calcium release, and improved vasodilation.