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A Common Strain of Dyspnea

Cassie Davenport, ACNP
Intermountain Medical Center
Murray, UT


A 42 year old male presents to the emergency department with progressive dyspnea x 4 days. He is tachycardic and tachypneic. Labs demonstrated moderate leukocytosis, positive troponin, and elevated BNP.


Common Strain of Dyspnea



What does this EKG demonstrate?


S1 Q3 T3 pattern

Though EKG changes arenonspecific and with limited value diagnostically, they are associated with a poorer prognosis (i.e. new right bundle-branch block, atrial arrhythmias, inferior Q waves, right axis deviation ST changes or T wave inversions, s1q3t3 pattern). They are seen in less than 10 percent of pulmonary embolism patients, and only half of patients with massive pulmonary embolism. This finding is not sensitive (54%) nor specific (62%). Causes of acute right heart strain other than pulmonary embolism can also this pattern.

Acute RV strain can cause slow R wave progression and precordial T wave inversions. It may also be associated with a QR complex in V1/V2 in which the precise mechanism has not been determined. Acute PE can also cause ST elevation in right chest leads (rare) and is most likely related to RV ischemia.

The patient above also had right axis deviation and poor R-wave progression, and an incomplete right bundle branch block.  Additional testing confirmed a saddle pulmonary embolism. Patient was treated with unfractionated heparin.


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