A nurse is reviewing a client's cardiac monitor. Which of the following findings should the nurse identify as an indication for synchronized cardioversion?

• Myocardial infarction: The rising troponin levels (Troponin T increasing from 0.08 ng/mL to 0.2 ng/mL and Troponin I rising from 0.01 ng/mL to 0.1 ng/mL) indicate myocardial injury. Persistent chest tightness, shortness of breath, diaphoresis, and anxiety suggest ongoing ischemia. The lack of complete pain relief after nitroglycerin further supports myocardial infarction rather than stable angina.
• Pulmonary embolism: Shortness of breath is a symptom of pulmonary embolism, but the absence of acute hypoxia, pleuritic chest pain, or significant coagulation abnormalities makes this less likely. The client's symptoms and laboratory findings more strongly support a cardiac etiology.
• Bleeding: While thrombolytic therapy increases bleeding risk, the aPTT (32 seconds) and platelet count (350,000/mm³) are within normal limits. There are no reported signs of active bleeding, such as hypotension, bruising, or hematuria, making this a less relevant immediate concern.
• Shortness of breath: Often present in myocardial infarction due to decreased cardiac output and pulmonary congestion. The combination of chest pain, diaphoresis, and dyspnea suggests worsening ischemia rather than a primary pulmonary process. However, it is a nonspecific symptom that can also indicate pulmonary embolism or respiratory distress.
• aPTT levels: Normal at 32 seconds (reference: 30–40 seconds), which suggests no immediate risk of abnormal clotting or excessive anticoagulation. This finding does not directly indicate myocardial infarction but is important in monitoring bleeding risk with thrombolytic therapy. A significantly elevated aPTT could raise concern for hemorrhagic complications.
• Elevated troponin levels: A highly specific marker for myocardial injury. The rise in Troponin T and Troponin I over time confirms myocardial damage, distinguishing acute coronary syndrome from stable angina. This trend is critical in diagnosing myocardial infarction, as troponin elevation correlates with the extent of cardiac muscle injury.

A. 1:1 ratio of P to QRS waves: Atrial fibrillation is characterized by chaotic atrial electrical activity, leading to the absence of distinct P waves. A 1:1 ratio of P to QRS waves is seen in normal sinus rhythm, not atrial fibrillation.

B. Absence of P waves: Atrial fibrillation causes rapid, disorganized atrial depolarization, resulting in the loss of identifiable P waves on ECG. Instead, fibrillatory waves are seen, and the ventricular response is irregularly irregular.

C. Prolonged PR interval: The PR interval represents the time between atrial and ventricular depolarization. In atrial fibrillation, there is no coordinated atrial depolarization, making the PR interval unmeasurable rather than prolonged.

D. Prolonged QT interval: A prolonged QT interval is associated with conditions like electrolyte imbalances, certain medications, and congenital syndromes, but it is not a typical feature of atrial fibrillation.