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See all posts in the network tagged with s1q3t3 56 year old female CC: Short of Breath – Conclusion No comments This is the conclusion to 56 year old female CC: Short of Breath. Be sure to check out the first post for the full story! When we left our crew they were just getting […]
This is the conclusion to 56 year old female CC: Short of Breath. Be sure to check out the first post for the full story!
When we left our crew they were just getting ready to leave the parking garage with a 56 year old female who was short of breath and dizzy after mild exertion. They had obtained IV access, a 3-Lead, and a 12-Lead ECG.
Let’s review our patient’s 3-Lead:
This is a regular, narrow complex tachycardia at 120 bpm with what appear to be sinus P-waves best appreciated in leads II and aVF. Given our patient’s tachypnea and dizziness, her tachycardia is likely a compensatory mechanism.
It is important that we find out what her body is compensating for!
Perhaps her 12-Lead can clue us in on her malady?
Her 12-Lead shows a sinus tachycardia with an incomplete right bundle branch block (the QRS duration is 100ms) and some diffuse ST/T-wave changes including some T-wave inversion and ST-depression.
These changes, when taken in the context of our patient’s breathlessness strongly suggest the patient is suffering from a pulmonary embolism! Given her chest pain, we should also consider acute coronary syndrome as her problems as well.
However, as Dr. Smith notes, T-wave inversions in Lead III and the anterior precordials are far more common in PE than in acute coronary syndrome.
I’ve marked up the 12-Lead to highlight some of the key features, including the S1Q3T3 pattern, incomplete right bundle branch block, and anterior T-wave inversions:
The patient’s condition remained stable throughout the transport and the crew elected to continue oxygen therapy and administer a fluid bolus.
While the surface ECG is not sensitive nor specific for pulmonary embolism, it often times can provide clues as to the diagnosis. Here is a list of changes seen in Pulmonary Embolism on the ECG adapted from Chou’s Electrocardiography in Clinical Practice ordered by their prevalence:
- 1. Sinus tachycardia (73%)
- 2. Prominent S-wave in Lead I (73%)
- 3. “Clockwise rotation” / late precordial transition (56%)
- 4. T-wave inversion in 2+ precordials (50%)
- 5. Incomplete or complete RBBB (20-68%)
- 6. P-pulmonale (28-33%)
- 7. Right axis deviation (23-30%)
- 8. No significant findings (20-24%)
- 9. S1Q3T3 (12-25%)
- 10. Supraventricular arrhythmias (12%)
During her stay in the emergency department it was confirmed that she was experiencing multiple small pulmonary emboli, and given their size they elected to start her on low molecular weight heparin and observe the patient overnight.
Moderate to severe pulmonary embolism may result in several ECG changes. The following ECG findings reflect right ventricular strain and are not specific for acute pulmonary embolism.
They may be useful when combined wih other clinical and laboratory findings.
T wave inversions in precordial leads V1-V4 with or without accompanying ST segment changes.
Complete or incomplete right bundle branch block (RBBB).
QR or qR pattern in lead V1.
S1Q3T3 pattern: S wave in lead I; new or increased Q wave in lead III; T wave inversion in lead III.
S1Q3T3 pattern is seen in approximately 10% of patients with acute pulmonary embolism.
Arrhythmias: most commonly atrial fibrillation.
Right axis deviation.
European Heart Journal 2008,29:2276-2315.
Am J Cardiol 1994;73:298-303.
Am J Cardiol 2007;99:817-821.
ECG 1a. ECG in acute pulmonary embolus. The patient had an acute onset chest pain. D-dimer level was 2 mcg/mL.
Even though it is not specific, T wave negativity in C1, C2 and C3 is the most common ECG sign of acute pulmonary embolism.
S wave is present in lead I (S1) and the T wave is negative in lead III (T3) but there is no Q wave in lead III (Q3).
S1Q3T3 is NOT frequently observed in acute pulmonary embolism. There is also right axis deviation: QRS complex is
biphasic in aVR, positive in III and negative in aVL. This ECG was recorded before the onset of thrombolytic therapy.
ECG 1b. The same patient’s ECG just after the completion of thrombolytic therapy with tPA.
Figure 1a. The same patient’s telecardiography shows prominent right pulmonary artery.
Figure 1b. Thorax CT showed enlarged right pulmonary artery and thrombus inside.
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