Pericardium Basics for the Physician Assistant Exam
The pericardium, the outer covering of the heart, can get inflamed and irritated from a variety of conditions. For the Physician Assistant Exam (PANCE) purposes, be familiar with pericarditis, pericardial effusion, and cardiac tamponade.
Pericarditis linked to multiple causes
Pericarditis is simply an inflammation of the pericardium. Causes of pericarditis may be viral (think Coxsackie B virus), autoimmune (think lupus), medication-induced (think cyclosporine, warfarin, and heparin), or malignant (think Kaposi’s sarcoma or metastatic disease from another solid tumor malignancy, most commonly lung carcinoma).
Uremic pericarditis is an effect of untreated, advanced kidney disease. And don’t forget about tuberculosis as a cause of pericarditis — tuberculosis can do just about anything. In case the list isn’t long enough, other possible causes of pericarditis are bacterial, fungal, radiation-induced, and that famous catch-all idiopathic (meaning “we don’t have a clue”).
Here are some key points concerning pericarditis:
The classic pain pattern of pericarditis is often pleuritic. The patient feels relief when sitting up and forward.
You can best hear an audible pericardial friction rub (think of Velcro) with the person sitting up and forward. The sound is often triphasic.
The treatment for pericarditis is initially indomethacin (Indocin), but prednisone and colchicine (Colcrys) can also be used if the condition is refractory to NSAIDs.
The typical ECG findings for acute pericarditis include diffuse ST elevation and PR segment depression.
Pericardial effusion is a buildup of fluid in the pericardial space. If it occurs gradually, there may not be any hemodynamic compromise. It comes in four flavors: transudative, exudative, hemorrhagic, and malignant. The big causes of a pericardial effusion, which are similar to the causes of pericarditis, are connective tissue disorders, malignancies, infections, and medications. Don’t forget tuberculosis as another cause of a pericardial effusion.
Look for chest pain, pressure symptoms, and on radiography, the so-called “water-bottle heart.” Look for Ewart’s sign (dullness to percussion). To make you crazy, we’ll also say that a small effusion may have no symptoms.
Here’s a possible PANCE subtlety: pericardial effusion is also present after a repair of atrial septal defect secundum (ASD).
How to relieve cardiac tamponade
Cardiac tamponade occurs when a pericardial effusion gets really big really, really quickly and in effect cuts off the left ventricle and blocks inflow. Picture the pericardium rapidly filling with fluid. Cardiac tamponade can be a cause of hypotension. Here are some key points about cardiac tamponade:
On physical examination, jugular venous distention (JVD), Kussmaul’s sign, and pulsus paradoxus can be present. Be familiar with these signs. (And please don’t confuse Kussmaul’s sign with Kussmaul respirations. Kussmaul’s respirations are tachypnea seen in the setting of a metabolic acidosis. Kussmaul’s sign is an increase in JVD on inspiration due to the pericardial effusion.) There are also diminished heart sounds.
The ECG shows decreased amplitude and poor R wave progression. Electrical alternans can also be present.
If a person has a Swan-Ganz catheter, you see equalization of pressures in someone with cardiac tamponade. The heart is literally getting squeezed in there. You see the pulmonary artery diastolic (PAD) pressure (an example of right-sided pressures) equal the pulmonary capillary wedge pressure (PCWP) (which is the awesomest way to measure left-sided pressures).
In contrast, in cardiogenic shock, the person usually has a PCWP that’s greater than the PAD pressure (reflecting a left-sided or systolic problem — a pumping problem), although both can be elevated.
You can confirm the diagnosis of cardiac tamponade by bedside echocardiogram. It shows collapse of the right atrium and ventricle. There can also be obstruction of the flow of blood from the left ventricle as the buildup of fluid causes shifting of the interventricular septum to the left. This is not good.
The treatment is a pericardiocentesis using the xiphoid process of the sternum as a guide.