**7. Investigations**

Diagnostic approach is summarized in Figure 1.[25]

**7.2. Chest radiography**

pulmonary arteries. [26]

**7.4. Echocardiography**

4 x (TRV)<sup>2</sup>

VSD and PDA).

valvular disease. [1],[24],[31], [32]

on the simplified Bernoulli's equation:

+ RA pressure

**7.5. Right heart catheterization**

and severe when PVR > or =5.0 Wood units. [34]

**7.3. Computed tomography and lung scanning**

"pruning" of the distal pulmonary vessels.

Radiographic signs of pulmonary hypertension include cardiomegaly or prominent central

Pulmonary Arterial Hypertension: An Overview

http://dx.doi.org/10.5772/56055

7

High-resolution chest CT scanning and ventilation-perfusion (V/Q) lung scanning are fre‐ quently obtained to help exclude interstitial lung disease and thromboembolic disease.

Radiographically, PH is said to be more likely when the main pulmonary artery diameter (MPAD) is > 29 mm (sensitivity 69%, specificity 100%) [27], [28] and/or the ratio of the main pulmonary artery to ascending aorta diameter is >1 [29]. The most specific CT findings for the presence of PH were both a MPAD > 29 mm and segmental artery-to-bronchus ratio of >1:1 in three or four lobes (specificity 100%) [30]. An additional feature of PH is rapid tapering or

Echocardiography is extremely useful for assessing right and left ventricular function, estimating pulmonary systolic arterial pressure, and evaluating for congenital anomalies and

Systolic pulmonary artery pressure is estimated using tricuspid insufficiency jet velocity based

Normal velocity is 2.0 – 2.5 m/s and a higher velocity indicates pulmonary hypertension,

Right heart catheterization measures right atrial pressure, mean pulmonary artery pressure (mean PAP), pulmonary artery occlusion pressure (PAOP), cardiac output (CO) by thermo‐ dilution / indirect Fick and mixed venous oxygen saturation. Right heart catheterization provides data to calculate the pulmonary vascular resistance (mPAP-PAOP)/CO and trans‐ pulmonary gradient (mPAP-PAOP). In addition right heart catheterization evaluates pulmo‐ nary vasoreactivity and helps in the diagnosis of left-to-right intracardiac shunts (e.g. ASD,

The normal resting mean PAP is 14 ± 3 mm Hg. The normal PAOP is from 6-12 mmHg. The normal pulmonary vascular resistance is 0.3-1.6 Wood Units. Transpulmonary gradient is normally ≤ 12 mmHg. Pulmonary hypertension (PH) is present when mean pulmonary artery pressure (PAP) is greater than 25 mm Hg. The severity of PH is further classified on the basis of mean pulmonary artery pressure as mild (25 to 40 mm Hg), moderate (41 to 55 mm Hg), or severe (> 55 mm Hg) [33] or mild to moderate when PVR is between 2.5 and 4.9 Wood units;

especially if there is associated dilation or dysfunction of the right ventricle.

Adapted with permission from ELSEVIER.(ref 25)

**Figure 1. Diagnostic Approach to Pulmonary hypertension.** 6 MWD indicates 6-minute walk test; ABGs, arterial blood gases; ANA, antinuclear antibody serology; CHD, congenital heart disease; CPET, cardiopulmonary exercise test; CT, computerized tomography; CTD, connective tissue disease; CXR, chest X-ray; ECG, electrocardiogram; HIV, human immunodeficiency virus screening; Htn, hypertension; LFT, liver function test; PE, pulmonary embolism; PFT, pulmona‐ ry function test; PH, pulmonary hypertension; RA, rheumatoid arthritis; RAE, right atrial enlargement; RH Cath, right heart catheterization; RVE, right ventricular enlargement; RVSP, right ventricular systolic pressure; SLE, systemic lupus erythematosus; TEE, transesophageal echocardiography; VHD, valvular heart disease; and VQ Scan, ventilation-perfu‐ sion scintigram.

#### **7.1. Electrocardiography**

ECG results are often abnormal in patients with PAH, revealing right atrial enlargement, right axis deviation, right ventricular hypertrophy, or large P wave and characteristic ST depression and T-wave inversions in the anterior leads. [26] However, a normal ECG does not exclude a diagnosis of PAH.

### **7.2. Chest radiography**

Radiographic signs of pulmonary hypertension include cardiomegaly or prominent central pulmonary arteries. [26]

#### **7.3. Computed tomography and lung scanning**

High-resolution chest CT scanning and ventilation-perfusion (V/Q) lung scanning are fre‐ quently obtained to help exclude interstitial lung disease and thromboembolic disease.

Radiographically, PH is said to be more likely when the main pulmonary artery diameter (MPAD) is > 29 mm (sensitivity 69%, specificity 100%) [27], [28] and/or the ratio of the main pulmonary artery to ascending aorta diameter is >1 [29]. The most specific CT findings for the presence of PH were both a MPAD > 29 mm and segmental artery-to-bronchus ratio of >1:1 in three or four lobes (specificity 100%) [30]. An additional feature of PH is rapid tapering or "pruning" of the distal pulmonary vessels.

#### **7.4. Echocardiography**

Echocardiography is extremely useful for assessing right and left ventricular function, estimating pulmonary systolic arterial pressure, and evaluating for congenital anomalies and valvular disease. [1],[24],[31], [32]

Systolic pulmonary artery pressure is estimated using tricuspid insufficiency jet velocity based on the simplified Bernoulli's equation:

#### 4 x (TRV)<sup>2</sup> + RA pressure

Normal velocity is 2.0 – 2.5 m/s and a higher velocity indicates pulmonary hypertension, especially if there is associated dilation or dysfunction of the right ventricle.

#### **7.5. Right heart catheterization**

Adapted with permission from ELSEVIER.(ref 25)

sion scintigram.

6 Pulmonary Hypertension

**7.1. Electrocardiography**

diagnosis of PAH.

**Figure 1. Diagnostic Approach to Pulmonary hypertension.** 6 MWD indicates 6-minute walk test; ABGs, arterial blood gases; ANA, antinuclear antibody serology; CHD, congenital heart disease; CPET, cardiopulmonary exercise test; CT, computerized tomography; CTD, connective tissue disease; CXR, chest X-ray; ECG, electrocardiogram; HIV, human immunodeficiency virus screening; Htn, hypertension; LFT, liver function test; PE, pulmonary embolism; PFT, pulmona‐ ry function test; PH, pulmonary hypertension; RA, rheumatoid arthritis; RAE, right atrial enlargement; RH Cath, right heart catheterization; RVE, right ventricular enlargement; RVSP, right ventricular systolic pressure; SLE, systemic lupus erythematosus; TEE, transesophageal echocardiography; VHD, valvular heart disease; and VQ Scan, ventilation-perfu‐

ECG results are often abnormal in patients with PAH, revealing right atrial enlargement, right axis deviation, right ventricular hypertrophy, or large P wave and characteristic ST depression and T-wave inversions in the anterior leads. [26] However, a normal ECG does not exclude a Right heart catheterization measures right atrial pressure, mean pulmonary artery pressure (mean PAP), pulmonary artery occlusion pressure (PAOP), cardiac output (CO) by thermo‐ dilution / indirect Fick and mixed venous oxygen saturation. Right heart catheterization provides data to calculate the pulmonary vascular resistance (mPAP-PAOP)/CO and trans‐ pulmonary gradient (mPAP-PAOP). In addition right heart catheterization evaluates pulmo‐ nary vasoreactivity and helps in the diagnosis of left-to-right intracardiac shunts (e.g. ASD, VSD and PDA).

The normal resting mean PAP is 14 ± 3 mm Hg. The normal PAOP is from 6-12 mmHg. The normal pulmonary vascular resistance is 0.3-1.6 Wood Units. Transpulmonary gradient is normally ≤ 12 mmHg. Pulmonary hypertension (PH) is present when mean pulmonary artery pressure (PAP) is greater than 25 mm Hg. The severity of PH is further classified on the basis of mean pulmonary artery pressure as mild (25 to 40 mm Hg), moderate (41 to 55 mm Hg), or severe (> 55 mm Hg) [33] or mild to moderate when PVR is between 2.5 and 4.9 Wood units; and severe when PVR > or =5.0 Wood units. [34]

### **7.6. Exercise testing**

This is very helpful to assess the efficacy of therapy. Severe exercise-induced hypoxemia should cause consideration of a right-to-left shunt. Cardiopulmonary exercise assessment with a widely available 6-minute walk test is commonly used to assess and track functional capacity. [1],[10], [24],[35],[36] However, it lacks specificity in that it cannot be used to discern between several causes of an impaired ability to walk.[10]

Additional Workup: includes:


Adapted with permission from ELSEVIER (ref 33)

unless there is a contraindication. [26]

Suppl):S78-84.

World Health Organization.

**8.1. Medical treatment**

*8.1.1. General measures*

Barst RJ, Gibbs JS, Ghofrani HA, Hoeper MM, McLaughlin VV, Rubin LJ, Sitbon O, Tapson VF, Galiè N. Updated evi‐ dence-based treatment algorithm in pulmonary arterial hypertension. J Am Coll Cardiol. 2009 Jun 30;54(1

Pulmonary Arterial Hypertension: An Overview

http://dx.doi.org/10.5772/56055

9

**Figure 2. Evidence-Based Treatment Algorithm.** (Drugs within the same grade of evidence are listed in alphabetical order and not order of preference). APAH = associated pulmonary arterial hypertension; ERA = endothelin receptor antagonist; HPAH = heritable pulmonary arterial hypertension; IPAH = idiopathic pulmonary arterial hypertension; IV = intravenous; PAH = pulmonary arterial hypertension; PDE-5 = phosphodiesterase type 5; SC = subcutaneous; WHO =

**•** Oral anticoagulation improves survival in IPAH and is recommended in all these patients

**•** Supplemental oxygen should be used to maintain oxygen saturation greater than 90%, especially because hypoxemia is a major cause of pulmonary vasoconstriction. Consider supplemental oxygen for PAH patients who are planning air travel, as mild hypobaric hypoxia can start at altitudes between 1500 and 2000 m, and commercial airliners are pressurized to the equivalent of an altitude between 1600 and 2500 m.[31]. Results suggest

