What are the other Names for this Condition? (Also known as/Synonyms)

• Segmental PH

What is Segmental Pulmonary Hypertension? (Definition/Background Information)

• Pulmonary hypertension (PH) is a disorder characterized by very high blood pressure (above normal) in the lungs due to a variety of causes. It should not be confused with systemic hypertension, otherwise known as ‘high blood pressure’
• The pulmonary blood vessels (arteries and veins) are usually a “low pressure” system, which means the blood pressure within the lung blood vessels is much lower than the rest of the body
• This elevated pulmonary blood pressure causes the right side of the heart to work harder, placing an increased burden on the heart. It is often caused by various lung and heart disease but can be associated with many other conditions too
• The World Health Organization (WHO) has clinically classified pulmonary hypertension according to certain groups. Segmental Pulmonary Hypertension forms part of WHO group 5 (sub group 5.4. Other disorders)
• Segmental Pulmonary Hypertension indicates that pulmonary hypertension is present in parts or segments of the lung but not in the entire lung; parts of the lung exhibit varying degrees of hypertension. It is a recently described classification, and experts have defined Segmental Pulmonary Hypertension in the following manner:
  • “Pulmonary hypertension in one or more lobes of one or both lungs”, per Nice World Pulmonary Hypertension Symposium 2013
  • “Pulmonary hypertension observed in discrete lung areas perfused by aortopulmonary collaterals in congenital heart diseases such as pulmonary or tricuspid atresia”, per International 2015 guidelines
• The chief risk factor for Segmental Pulmonary Hypertension is congenital heart diseases, particularly congenital pulmonary artery stenosis, complex pulmonary atresia, and abnormal origin of the right pulmonary artery. The cause of development of Segmental PH is not well-established
• The signs and symptoms of Segmental Pulmonary Hypertension may include shortness of breath, chest pain, fatigue, and dizziness. Following a diagnosis of the condition, the treatment measures may involve the use of medications, such as calcium channel blockers, and bringing about certain lifestyle modifications, among others
• The prognosis of Segmental Pulmonary Hypertension may be improved if the condition is diagnosed promptly and treated appropriately. However, the overall prognosis depends on several factors including on the severity of the condition; it may vary from one individual to another

Who gets Segmental Pulmonary Hypertension? (Age and Sex Distribution)

• Segmental Pulmonary Hypertension is mostly observed in children with certain specific congenital heart diseases

• Both males and females are affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Segmental Pulmonary Hypertension? (Predisposing Factors)

The risk factors for Segmental Pulmonary Hypertension may include the following heart and/or lung conditions:

• Absence of a single pulmonary artery
• Aortopulmonary window
• Atrioventricular septal defect (AVSD)
• Complex pulmonary atresia
• Hemitruncus arteriosus
• Patent ductus arteriosus
• Systemic arterial supply to the lungs
• Truncus arteriosus

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Segmental Pulmonary Hypertension? (Etiology)

Pulmonary hypertension is caused by an increased blood pressure within the blood vessels of the lung.

According to medical literature, Segmental Pulmonary Hypertension is defined in the following manner:

• at least 1 segment of the pulmonary vasculature is nonhypertensive,
• each hypertensive area may present with different severity, and
• symptoms depend on ventilation-to-perfusion mismatch.

Reference: Dimopoulos K, Diller G, Opotowsky A, et al. Definition and management of segmental pulmonary hypertension [published July 4, 2018]. J Am Heart Assoc. doi:10.1161/JAHA.118.008587

What are the Signs and Symptoms of Segmental Pulmonary Hypertension?

The signs and symptoms of Segmental Pulmonary Hypertension depends on a set of several factors that include age of the individual, overall health of the individual, and associated health conditions.

The common signs and symptoms of pulmonary hypertension include:

• Progressive shortness of breath (especially while exercising), is the most common symptom
• Fatigue (frequent tiredness)
• Chest pain
• Dizziness and fainting
• Swelling of the ankles/legs
• Palpitations
• Bluish lips and skin, observed during the later stages
• Irregular heartbeat (arrhythmias)
• Fluid in the abdomen (ascites)

Additionally, the signs and symptoms of any underlying or associated heart/lung condition may be noted.

How is Segmental Pulmonary Hypertension Diagnosed?

The diagnosis of Segmental Pulmonary Hypertension may often be challenging. The preliminary procedures may include:

• A complete physical examination of the patient 
• A thorough checking of the patient’s medical history and a detailed checking of the family history of the patient
• Blood tests:
  • Blood tests help rule out other diseases
  • They also help in checking the blood oxygen levels
  • The measurement of brain natriuretic peptide (BNP) can be used to assess the strain on one’s heart
• Chest X-ray: Chest X-rays can reveal structural signs of pulmonary hypertension by identifying changes in the pulmonary arteries or enlargement of the right side of the heart
• Electrocardiogram (ECG): An electrocardiogram checks the electrical impulses of the heart. There are certain identifiable patterns on an ECG that may indicate pulmonary hypertension. However, ECG is not specific enough to diagnose the condition by itself, so a combination of tests may be recommended by the healthcare provider
• Echocardiogram: In this procedure, a sonogram of the heart is taken and used to measure overall functioning as well as measure the pressure within the chambers of the right heart. An echocardiogram is also often times used to monitor a patient’s condition after diagnosis and during treatment
• Pulmonary function tests: These tests help measure the quality of breathing and check the functioning of the lungs (such as how much air is breathed in and out, as well as the quality of oxygen exchange)
• Exercise tolerance test (six-minute walk test): This helps to measure the patient’s ability to exercise
• Nuclear scan (ventilation/perfusion scan or V/Q scan): This tool helps identify any new or chronic blood clots in the vessels of the lungs that could be causing pulmonary hypertension
• Tests and exams related to the underlying/associated conditions, as necessary, may be undertaken

The gold standard for pulmonary hypertension diagnosis and management is right-heart catheterization and acute vasodilator challenge.

• Right-heart catheterization:
  • If pulmonary hypertension is suspected based off preliminary tests and procedures, a right-heart catheterization test is ordered to help confirm the diagnosis
  • This test can accurately quantify right-heart pressures (measure the pressure within the chambers of the right heart), especially the pressure inside the pulmonary arteries
  • During this procedure, a very small catheter is inserted into a large vein (either within the patient’s groin or neck) and passed into the patient’s heart and vasculature to measure the internal blood pressures 
• Vasodilator study (acute vasodilator challenge):
  • While this test is not used to necessarily “diagnose” pulmonary hypertension, it is used to evaluate the patient for possible therapeutic management
  • Like right-heart catheterization, a catheter is placed within the pulmonary artery to test for vasodilation (or relaxation) in response to a class of medications called calcium channel blockers (CCBs)
  • The response and dosing of CCBs can be evaluated with this procedure

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Segmental Pulmonary Hypertension?

The complications of Segmental Pulmonary Hypertension depends on a set of several factors that include the age of the individual, overall health of the individual, underlying conditions, and promptness of diagnosis. 

Following are the possible complications that may arise due to the condition:

• Right-sided heart failure with hepatic congestion (due to deposition of stones in the liver)
• Pedal edema: Swelling of the leg or ankle
• Pleural effusions: Building-up of excess fluid around the lungs
• Worsening dyspnea (shortness of breath) upon exertion

Complications due to associated heart and/or lung conditions may be additionally noted

How is Segmental Pulmonary Hypertension Treated?

The treatment of Segmental Pulmonary Hypertension depends on a set of several factors that include the severity of the signs and symptoms, age of the individual, and overall health of the individual. A treatment of the associated heart/lung condition is essential.

Segmental Pulmonary Hypertension is best treated at a medical center with appropriate expertise. Several medical treatments are highlighted below:

• Conventional medical therapies:
  • Calcium channel blockers (CCBs): These are a group of medications that help vasodilate (or relax) the arteries. However, CCBs are only appropriate for patients demonstrating a favorable response to the vasodilator study
  • Inotropic agents: These are medications that assist in the pumping of the heart 
  • Diuretics, salt limitation, and weight monitoring may be recommended, to limit excess strain on the heart
  • Supplemental oxygen may help an individual meet the ‘oxygen needs’ for normal daily activities
  • Blood thinners: These medications help prevent blood clots, especially in the lung blood vessels
  • Treating underlying diseases or conditions
• Oral, inhaled, subcutaneous, or intravenous treatment options:
  • Endothelin receptor antagonists (ERAs) help in preventing pulmonary blood vessels from narrowing which helps keep the pressures towards normal levels
  • Phosphodiesterase inhibitors (PDE 5 Inhibitors), prostacyclin analogues, and soluble guanylate cyclase (sGC) stimulators, all aid in allowing vessels of the lungs to vasodilate (or relax)
• Additional treatment options may include:
  • Lifestyle modifications, such as nutrition, exercise, avoiding tobacco, and limiting alcohol consumption, are beneficial
  • Judicious exercising may be effective in limiting deconditioning (by building stamina), improving the quality of life, and exercising capacities. Isometric exercises, such as heavy weightlifting, should be avoided
  • Other treatments, depending on the etiology (cause) of pulmonary hypertension, may include various cardiothoracic procedures
  • Lung transplantation may be required with advanced forms of the disorder

How can Segmental Pulmonary Hypertension be Prevented?

The preventative measures for Segmental Pulmonary Hypertension are related to the cause of the condition. In a majority of cases, it may not be able to prevent congenital heart diseases that are associated with Segmental PH.

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis Segmental Pulmonary Hypertension? (Outcomes/Resolutions)

• The prognosis of Segmental Pulmonary Hypertension differs from one individual to another, depending on its severity and on the extent of underlying or associated heart/lung condition

• Individuals with mild conditions have better prognosis than those with severe symptoms and complications. Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Segmental Pulmonary Hypertension:

The following DoveMed website links are useful resources for additional information:

https://www.dovemed.com/diseases-conditions/patent-ductus-arteriosus-pda/

https://www.dovemed.com/diseases-conditions/pulmonary-valve-atresia/

https://www.dovemed.com/diseases-conditions/unilateral-absence-pulmonary-artery/