Tension pneumothorax presenting as ST segment elevation: Look,Listen,Act!

Abstract

We present a unique case of a patient with a tension pneumothorax that presented with electrocardiogram (ECG) characteristics typical for ST segment elevation myocardial infarction. The clinical diagnosis was clinched by focused physical examination. Treatment of the pneumothorax lead to resolution of the electrocardiographic abnormalities. Our experience from this unique case is useful for cardiologists and critical care physicians who encounter these patients routinely.

Case

A 64-year-old man with past medical history only notable for chronic obstructive pulmonary disease presented to the emergency room with progressively worsening shortness of breath and productive cough over 2 days. On examination, he was found to have diffuse wheezes bilaterally over the chest. Laboratory work revealed leukocytosis with a left lower lobe pneumonia on the chest radiograph. He was initiated on bi-level positive airway pressure for respiratory acidosis. Soon after, he developed an alteration in mental status and a decision was made to initiate invasive mechanical ventilation. He was preoxygenated with bag-mask ventilation and intubated via direct laryngoscopy. Within minutes of intubation, he started becoming hypotensive to 80/60 mmHg, and hypoxemic with an oxygen saturation of 86%. On telemetry leads, he was found to have an acute change, with presence of ST elevations. Electrocardiogram (ECG) confirmed ST segment elevations with a right bundle branch in V1, V2, V3; concerning for an acute myocardial injury (Figure 1). Lung auscultation at the same time revealed decreased breath sounds on the right, concerning for pneumothorax. This was confirmed by an urgent portable chest radiograph (Figure 2). The patient underwent stat needle decompression in second intercostal space followed by tube thoracostomy with an 18F chest tube. Interestingly, all his ECG changes reverted back to baseline with the placement of the chest tube, which resulted in resolution of his pneumothorax (Figure 3). Serial cardiac enzymes were negative. He continued to improve through his hospital stay and was discharged home on day 10.

Figure 1.

Electrocardiogram showing ST segment elevation in leads V1–V3 with reciprocal ST depressions in inferior and lateral leads.

Figure 2.

Chest radiography showing a large right pneumothorax (arrows point to lung margins).

Figure 3.

Electrocardiogram obtained after resolution of pneumothorax showing resolution of ischemic changes.

Discussion

Few case reports in literature have described ECG changes in pneumothorax. Possible mechanisms for these ECG changes include cardiac rotation, acute right ventricular dilatation from hypoxia, decrease in preload due to increased intrathoracic pressure, and decreased coronary flow reserve. ¹ Previous case reports of ECG changes in tension pneumothorax described ST changes in the inferior and lateral leads. In the current case, we observed ST elevation in leads V1–V3, with reciprocal ST depressions in the inferior leads. These findings most likely represent a pattern of right ventricular strain. Previously, externally applied pressure overload has been shown to induce ST segment elevation in an experimental right ventricular wedge preparation. ² The possible underlying mechanisms in our patient with tension pneumothorax could include hypotension induced subendocardial ischemia, compression of the right ventricle by the air accumulated in the right pleural cavity and increased pulmonary artery pressure with right ventricular strain. This case highlights the importance of being aware of tension pneumothorax induced ECG changes as well as the paramount role bedside physical examination plays in emergent management.