What Are Pericarditis and EKGs?
Pericarditis is a medical condition characterized by inflammation of the pericardium, which is the thin, two-layered sac surrounding the heart. This sac contains a small amount of fluid that helps reduce friction as the heart beats. When the pericardium becomes inflamed, these layers can rub against each other, causing discomfort and affecting the heart’s function. The most common causes are viral infections or often remain unknown.
An electrocardiogram, commonly known as an EKG or ECG, is a simple and non-invasive test that records the electrical activity of the heart. Electrodes placed on the skin detect the tiny electrical signals generated by the heart muscle as it contracts and relaxes. These signals are then displayed as waves on a monitor or printed on paper. An EKG helps doctors assess the heart’s rhythm, rate, and the overall health of its electrical pathways.
How Pericarditis Appears on an EKG
Pericarditis frequently presents with distinct changes on an EKG, which are often a significant clue for diagnosis. A common finding is widespread ST-segment elevation, meaning an upward shift in a specific part of the EKG waveform. This elevation is typically described as “concave upward” or “saddle-shaped,” resembling a gentle upward curve. Unlike some other heart conditions, these ST-segment elevations are usually diffuse, appearing in many leads across the EKG rather than being confined to a specific area.
Another characteristic EKG change in pericarditis is PR-segment depression, a downward shift before the QRS complex. This is common in early stages. While not every patient shows all changes, widespread ST-segment elevation and PR-segment depression are common EKG criteria for diagnosing acute pericarditis. These alterations reflect inflammation of the pericardial sac and sometimes the underlying epicardium.
The Changing EKG Over Time
The EKG changes associated with pericarditis are not static; they evolve through stages as the condition progresses. This dynamic nature of the EKG is a hallmark of the disease. The first stage, which can last for days to weeks, is characterized by widespread ST-segment elevation and PR-segment depression. This is the acute phase where inflammation is most active.
In the second stage, the ST and PR segments begin to normalize, returning closer to the baseline, and T-waves may flatten. The third stage involves T-wave inversion, appearing as downward deflections on the EKG after ST segments normalize. Finally, the fourth stage is marked by complete EKG normalization, with T-waves returning to their upright position. Not all patients progress through all four stages, and the timeline for changes can vary.
Other Ways to Diagnose Pericarditis
While EKG changes are important, diagnosing pericarditis relies on a combination of factors. Patient symptoms are primary, with typical chest pain a key indicator. This pain is often sharp, located in the center or left chest, and may worsen when lying down or taking deep breaths, often finding relief by leaning forward. A physical examination may reveal a pericardial friction rub, an audible grating sound heard with a stethoscope as inflamed layers rub.
Blood tests can show elevated inflammatory markers, such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). Imaging studies like an echocardiogram, which uses sound waves to image the heart, can detect fluid accumulation around the heart, known as a pericardial effusion. The presence of an effusion can further support the diagnosis of pericarditis.
Similarities to Other Heart Conditions
The EKG changes in pericarditis can be confused with other heart conditions, particularly a heart attack (myocardial infarction). Differentiating between these conditions is important for appropriate treatment. In pericarditis, the ST-segment elevation is widespread across many EKG leads and has a concave-upward shape. This suggests generalized inflammation.
Conversely, a heart attack causes ST-segment elevation localized to specific heart areas, corresponding to the affected coronary artery, and often has a convex-upward or “dome-shaped” appearance. Heart attacks may also present with reciprocal ST-segment depression in leads opposite to the area of elevation, a finding less common in pericarditis. Understanding these EKG differences helps medical professionals accurately diagnose and manage these distinct cardiac issues.