Physician Assistant Exam: Pulmonary Embolism and Hypertension
Pulmonary embolism and pulmonary hypertension are two pulmonary circulation conditions that are high-yield for the Physician Assistant Exam (PANCE). And for good reason, too — you see these conditions clinically time and time again.
Blood clots: The pulmonary embolism
As the name suggests, a pulmonary embolism (PE) is an obstruction of the pulmonary artery or one of its many branches due to embolus. A pulmonary embolism is commonly due to a deep venous thrombosis (DVT).
Common presenting symptoms include sudden onset pleuritic chest pain, sweating, and tachycardia. Physical examination can reveal tachycardia, low blood pressure, and/or hypoxemia, depending on the extent of the clot.
ABG can show hypoxemia as well as a respiratory alkalosis secondary to tachypnea. The most common ECG finding is sinus tachycardia. You may also see right axis deviation and T wave inversion in the anterior leads. In addition, there can be poor R wave progression. The S1Q3T3 pattern is present less than 10 percent of the time.
You can order various imaging studies to evaluate for a pulmonary embolism: ECG, chest radiograph, and ventilation/perfusion (V/Q) scan. As with the ECG, the chest radiograph is usually normal. The V/Q scan looks for ventilation/perfusion mismatching. You can interpret V/Q scans as low, intermediate, or high probability. High probability is diagnostic for a pulmonary embolism. However, if a person has underlying lung disease, the V/Q scan isn’t a reliable test.
The gold standard for evaluating the pulmonary vasculature is the angiogram. However, given advances in radiologic imaging, the CT angiogram has become a popular method (and perhaps the preferred choice) for identifying a pulmonary embolism.
Remember that the diagnosis of a pulmonary embolism is based on clinical suspicion. If someone has risk factors that would increase the risk of developing deep venous thrombosis and/or pulmonary embolism, act on it. Even if someone has a low probability V/Q scan, it doesn’t rule out a pulmonary embolism. Virchow’s triad is a way of examining for possible risk factors for deep venous thrombosis and/or pulmonary embolism.
If you have a high clinical suspicion that a person has a pulmonary embolism, start anticoagulation therapy with intravenous heparin. Thrombolytics are used for people with major pulmonary embolism such as a saddle embolus, which can be fatal if not treated super aggressively.
Which one of the following is associated with the presence of a pulmonary embolus?
(A) Sinus bradycardia
(B) Right ventricular hypokinesis on echocardiogram
(C) Diffuse ST segment elevation
(D) Kerley B lines
(E) ST elevation in the anterior leads
The correct answer is Choice (B). With a significant pulmonary embolism, you see right ventricular hypokinesis, given the acute high pressures in the pulmonary artery secondary to the pulmonary embolism. Concerning Choice (E), ST elevation in two contiguous leads is the definition of a myocardial infarction.
Diffuse ST segment elevation, Choice (C), is associated with acute pericarditis. PR segment depression is also a common ECG finding with pericarditis. You’d expect to see sinus tachycardia, not sinus bradycardia, Choice (A), with pulmonary embolism. An inferior wall myocardial infarction can present with sinus bradycardia. Choice (D) is seen on a radiograph of someone with congestive heart failure.
Take the pressure off pulmonary hypertension
Pulmonary hypertension is an increase in blood pressure in the pulmonary artery, pulmonary vein, or pulmonary capillaries. A cardiac echocardiogram can suggest elevated pulmonary pressures; however, the definitive test is a right heart catheterization.
Pulmonary hypertension comes in two types, and they have simple names — primary and secondary:
Primary: Primary pulmonary hypertension is an uncommon form of pulmonary hypertension that mainly affects women in their late 20s and early 30s. Treatment consists of long-term anticoagulation with warfarin and intravenous prostaglandins like epoprostenol. Calcium channel blockers can be used in treating primary pulmonary hypertension, but they need to be controlled. Not everyone responds to calcium channel blockers, so pulmonary pressures need to be monitored by pulmonary artery catheterization.
Other medications used in the treatment of primary pulmonary hypertension can include sildenafil (Viagra or Revatio) and bosentan (Tracleer). Sildenafil is an example of a phosphodiesterase inhibitor, which helps improve pulmonary blood flow. Bosentan is an example of an endotheial receptor antagonist that’s used to improve blood flow and vasodilate the pulmonary artery. Endothelin is a potent vasoconstrictor. Side effects of this medication include hypotension and elevated liver function levels.
Secondary: Secondary pulmonary hypertension has many etiologies. The most common cause of right heart problems is left heart problems. Left ventricular systolic dysfunction, diastolic dysfunction, and valvular problems (for example, mitral regurgitation) can all cause secondary pulmonary hypertension.
Many of the pulmonary problems can cause secondary pulmonary hypertension. For example, as COPD advances, it can cause right heart failure, termed cor pulmonale. Treatment, which can be difficult, can involve the use of diuretics and management of the underlying condition. Medications to try to lower pulmonary pressures can also be used, depending on the cause of the cor pulmonale (that is, primary versus secondary pulmonary hypertension).
Connective tissue disorders, such as scleroderma and mixed connective tissue disease (MCTD), can cause secondary pulmonary hypertension as well.