Complex Electrocardiographic Interpretation in an Acutely Ill Patient With Hemodynamic Compromise

Scenario: A 68-year-old man with a history of hypertension and chronic kidney disease came to the emergency department (ED) with acute respiratory distress. He had experienced intermittent labored breathing starting 3 days earlier that had become persistent the preceding night, so he came to the ED that morning. At presentation, he was febrile (39.2 °C), tachypneic (28/min), tachycardic (110-150/min), hypotensive (88/54 mm Hg), and restless. Oxygen was administered at 4 L/min via nasal cannula (oxygen saturation via pulse oximetry, 92%). Point-of-care lactate level was 3.9 mmol/L (normal, 0.5-2.0 mmol/L), sodium 140 mEq/L (normal, 135-145 mEq/L), and potassium 3.3 mEq/L (normal, 3.5-5.2 mEq/L). High-sensitivity troponin was 15 ng/L (normal, <14 ng/L). The nurse promptly recorded a 12-lead electrocardiogram (ECG, below) and activated the sepsis protocol given the patient’s signs and symptoms.Atrial fibrillation (AF) with rapid ventricular response at a heart rate of 150/min, right bundle branch block (RBBB), right-axis deviation, and possible myocardial ischemia with right ventricular (RV) involvement.Although AF is not uncommon in sepsis, due to systemic inflammation, in this case, the presence of RBBB, right-axis deviation, and T-wave inversion in leads V1 through V4 indicates that RV strain is present, suggesting that there is a pulmonary component. Reciprocal depression in leads I and aVL, in the context of a tachyarrhythmia (AF in this case) and respiratory distress also supports RV strain or acute cor pulmonale. Possible causes include severe pulmonary hypertension from sepsis-associated pneumonia or pulmonary embolism; both require rapid evaluation to confirm or rule out. Also noteworthy is the presence of ST-segment elevation, isolated in lead III, but not the other inferior leads (II and aVF), which raises suspicion of inferior wall myocardial ischemia (ie, RV infarct). The initial troponin level was slightly elevated, so serial troponin levels should be obtained. A B-type natriuretic peptide blood test might also be useful to diagnose heart strain and fluid overload, indicating heart failure versus ischemia. The patient’s signs and symptoms and the presence of AF with rapid ventricular response, RBBB, and right-axis deviation support the overall impression of RV strain as opposed to coronary occlusion.An acute increase in pulmonary vascular resistance (cor pulmonale) produces sudden and increased afterload in the right ventricle. Ventricular dilation and wall stress that follows can disrupt conduction down the right bundle branch, resulting in RBBB. Additionally, extreme increases in RV pressure can lead to subendocardial ischemia from reduced perfusion due to mechanical stretch (rather than primary coronary occlusion), which manifests as T-wave inversions in the anterior leads and reciprocal ST-segment depression in leads I and aVL. Regardless, the forward blood flow into the lungs and subsequently the left ventricle can be compromised and result in reduced cardiac output (cardiogenic shock).Immediate primary goals are to stabilize oxygenation with close monitoring of respiratory status, slow the heart rate and control rhythm, and maintain hemodynamics. Anticipate and prepare for bedside echocardiography, computed tomography pulmonary angiography, anticoagulation therapy (if RV strain is identified), and antiarrhythmic drugs (eg, amiodarone) for AF rate control in hypotensive patients. As noted above, a B-type natriuretic peptide blood test may be useful.In this scenario, the patient had pneumonia that led to sepsis. A review of the previous 12-lead ECGs showed that the patient had no history of AF. The patient was transferred to the intensive care unit and underwent extensive evaluation and diagnostic testing. Pulmonary embolism and RV infarction were ruled out, and his electrolyte levels were closely monitored and corrected because of his chronic kidney disease and to prevent potential arrhythmias. The patient remained in the intensive care unit for 6 days and his status improved, including return of sinus rhythm, following the treatment of his pneumonia and sepsis. He was later discharged home following a 3-day stay in the step-down unit.