Pulmonary hypertension: Clinical sciences

Pulmonary hypertension, or PH for short, refers to an abnormally high pressure in the pulmonary circulation, which is divided into five main groups based on etiology. Group I refers to pulmonary arterial hypertension; Group II is PH due to left heart disease; Group III PH is associated with chronic lung disease or hypoxia; Group IV PH is due to pulmonary artery obstruction; and finally, Group V is PH with unclear or multifactorial mechanisms.

Now, if your patient presents with a chief concern suggesting PH, perform an ABCDE assessment to determine if they are unstable or stable. If unstable, stabilize their airway, breathing, and circulation, which might require endotracheal intubation and mechanical ventilation. Next, obtain IV access and put them on continuous vital sign monitoring, as well as cardiac telemetry; and if needed, don’t forget to provide supplemental oxygen. Finally, in some cases, you might need to place an indwelling pulmonary artery catheter, also known as a Swan-Ganz catheter.

Next, obtain a focused H&P. Your patient will typically report shortness of breath and chest discomfort, while their physical exam will usually reveal hypotension and tachycardia. You might also notice signs of right-sided heart failure, such as a right ventricular heave; jugular venous distention, with hepatojugular reflux; lower extremity edema; and cool extremities. On auscultation you might notice a loud P2 or a holosystolic murmur from tricuspid regurgitation.

At this point, suspect cardiogenic shock. Then order labs, including BNP; as well as a 12-lead ECG, chest X-ray, and echocardiogram. Labs will show an elevated BNP. ECG will likely reveal right axis deviation; peaked P-waves on lead v2, indicating right atrial enlargement; and R-waves greater than 7mm in lead v1, consistent with right ventricular hypertrophy. The chest X-ray often reveals cardiomegaly. Finally, echocardiogram usually shows elevated estimated pulmonary artery pressure and right ventricular strain with hypertrophy or dilation. At this point, diagnose cardiogenic shock due to PH!

Once you diagnose cardiogenic shock due to PH, proceed with management. This primarily relies on decreasing right ventricular preload with loop diuretics, such as furosemide, along with sodium and fluid restriction. If diuretics are ineffective, you may also consider ultrafiltration. Next, decrease PA afterload using short-acting inhaled vasodilators, such as nitric oxide.

Next, try to increase heart contractility using inotropes, like dobutamine and milrinone; and vasopressors, like norepinephrine. In severe cases, you might need advanced interventions, like mechanical circulatory support and extracorporeal membrane oxygenation.

Okay, now let’s go back to the ABCDE assessment and discuss stable patients. First, obtain a focused history and physical exam. Your patient is likely to report dyspnea at rest and with exertion, fatigue, chest discomfort, and sometimes even syncope. The physical exam will show signs of right-sided heart failure, such as jugular venous distention, possibly with hepatojugular reflux, and lower extremity edema. Additional physical exam findings might include right ventricular heave. On auscultation you may hear a loud P2, right-sided S3, and holosystolic murmur.

With these findings, suspect PH, and obtain a 12-lead ECG, chest X-ray, and echocardiogram. On ECG, you’re likely to see right axis deviation, right atrial enlargement, and right ventricular hypertrophy; while the chest X-ray commonly shows cardiomegaly. Finally, the echocardiogram typically reveals an elevated estimated pulmonary artery systolic pressure; right ventricular strain; tricuspid regurgitation; as well as right atrial and right ventricular enlargement. With these findings, diagnose pulmonary hypertension.

Next, assess the underlying cause and categorize your patient’s pulmonary hypertension by etiologic group using the World Health Organization classification. To do this, order a chest CT scan, CT pulmonary angiogram, pulmonary function tests, sleep study, and a ventilation-perfusion scan. In some cases, you may also need a right- or left-heart catheterization.

First, let’s start with Group I, which refers to pulmonary arterial hypertension, or PAH for short! These patients have thick and narrow arteries, which can be idiopathic or due to various conditions. For example, a mutation of the BMPR2 gene, which provides instructions for growth and differentiation of cells, including those in the walls of the small arteries of the lungs; connective tissue conditions like scleroderma; HIV; liver disease; and even certain medications and toxins, including stimulants like amphetamines and tyrosine kinase inhibitors like dasatinib.

To diagnose Group I pulmonary hypertension, your patient should have no evidence of left heart disease, chronic lung disease, hypoxia, and chronic thromboembolic disease. Okay, to confirm the diagnosis, the right heart catheterization must demonstrate: elevated mean pulmonary artery pressure, typically 20 mmHg or more; a pulmonary vascular resistance of 2 Wood units or more; and a normal pulmonary capillary wedge pressure, typically less than 15 mmHg. With these findings, diagnose PAH!

Okay, moving on to management. Initiate treatment with supplemental oxygen, loop diuretics like furosemide, and a pulmonary rehabilitation program. Additionally, administer vasoactive agents, beginning with calcium channel blockers, like nifedipine. If calcium channel blockers are not effective, consider PDE5-inhibitors, like sildenafil; endothelin receptor antagonists, like bosentan; prostacyclins, like treprostinil; and soluble guanylate cyclase stimulators, like riociguat.