Pulmonary embolus (PE) is a relatively common finding in the emergency room setting. Following heart attack and stroke, PE holds steady to the number three spot for cardiovascular disease-related deaths (Abaca, Baddi & Manrique, 2014) A PE occurs when an occlusion of the pulmonary vasculature obstructs or altars pulmonary blood flow. A person with a PE may be asymptomatic entirely. While, conversely, the first symptom may even be death (Konstantinides et al., 2014). According to Co, Eilbert, & Chiganos (2017), PE occurs in 600,000 people in the US each year with an acute fatality rate ranging from 7%-11%. Cygan, Weizberg, & Hahn (2016) state that of the 200,000 annual new cases of venous thromboembolism (referring to an emboli in a vein outside the lung) there is a 6% 30-day fatality rate from PE.
Diagnosis of PE occurs after several non-invasive diagnostic tests are performed. These include blood tests, CT Angiography (CTA), Ventilation/Perfusion scan (VQ Scan), and pulmonary artery angiography. Combined with a thorough history, the patient’s clinical orientation, oxygen saturation, respiratory rate, cardiac rate and rhythm, diagnosis can most often be ascertained with a great deal of accuracy. However, despite all the technological advances in imaging modalities, Co et al. (2017) contend that a small percentage of PE’s slip through the cracks and are not even discovered until autopsy (upwards of 30%).
Its my goal here to strengthen the case for the implementation and use of electrocardiogram (ECG) as an added diagnostic tool when assessing for PE. In my experience in the emergency department, it has been that ECG is the least considered diagnostic tool in regard to aiding in diagnosing PE. Obviously, in all major cities in the US (and even some smaller towns) there are more complex equipment with higher specificity and sensitivity than ECG. However, Quaddoura et al. (2017) argues ECG is one of the very first diagnostic tests performed in the ER and is non-invasive, rapidly interpretable, financially cost-effective, and in most cases available in remote regions of the country where other diagnostic tools may be limited in availability. Because cardiovascular collapse can occur quickly, rapid diagnosis and treatment can prevent or reduce often times critical sequela (Cyan et al., 2015). ECG can be the tool to bridge that gap.
McGinn and White first discovered and reported in the Journal of American Medical Association (1935) ECG patterns that correlate with those diagnosed with PE. The most “famous” of these phenomena, the S1Q3T3 pattern, has been dubbed the McGinn-White sign (Rawal, Yadav, Kumar, & Sujana, 2017). This refers to the presence of an S-wave in Lead I, a Q-wave in Lead III and an inverted T-wave in Lead III. And although this particular pattern may be the most “famous”, Rawal et al. (2017) claim its frequency of presence in those presenting with acute pulmonary embolus (APE) is approximately only 20%. Co et al. (2017) found in their study that a very low 3.7% of those diagnosed with PE demonstrated this finding on ECG, while a study published in 2011 by Raqhav, Makkuni, & Figueredo (2011) claimed this finding to occur in upwards of 30% of all PE sufferers they studied. Since 1935 more than 20 different ECG changes have been reported.
Cadourra et al. (2017) meta-analysis and systematic review found there to be very specific ECG patterns associated with increased risk of death from APE in the hospital setting. These patterns include S1Q3T3, Complete RBBB, TWI, ST-segment depression in V4-V6, STE-V1, STE-III, Qr-V1, RAD, AF, and RV transmural ischemic pattern. Although an older study, Ferrari et al. (1997), found that the most clinically significant ECG pattern in massive PE was TWI in precordial leads, which has even occurred earlier in onset in some of the most severe cases. These ECG patterns reflect the great deal of right ventricular strain (RV strain) that occurs with congestion or altered blood flow within the pulmonary vasculature with PE (Abarca et al., 2014).
In 2001 the “Daniel Score” was created by Daniel et al. in order to ascertain the presence and severity of pulmonary hypertension from Acute Pulmonary Embolus (APE). This score included many other patterns noticed on ECG including tachycardia, right bundle branch block (RBBB), and T-wave inversion (TWI). The score ranged from 0-21, with a higher score indicating increased severity. Other scoring techniques have emerged since the Daniel score. Notably, the TwiST score developed by Hariharen et al. in 2015, was found to be slightly higher in sensitivity than the Daniel Score in predicting a worse outcome. Scoring systems such as these have highlighted and demonstrated the ECG as a valuable tool for PE identification and prognostication.
In summation, because of its ease of use, its rapid interpretation and availability in almost any hospital or clinical setting, ECG has proven to be an effective and useful diagnostic tool in assessing for the potential presence of and severity of PE. It does not take a whole lot of additional training to learn those common 20+ ECG patterns that have been known to occur with PE. I would encourage nurses, ECG techs, as well as others that perform frequent ECGs to learn those phenomena in order to assist in recognizing a potential PE when they occur.
Thanks for taking the time to read this blog! I hope you gained some great insight from this piece. I know I did! Remember friends, we don’t learn information just to pass tests. We learn this useful information because one day we may be the only person standing between life and death for a patient. Please feel free to share with someone you think may benefit from reading.
Abarca, E., Baddi, A., & Manrique, R. (2014). ECG manifestations in submassive and massive pulmonary embolism. Report of 4 cases and review of literature. Journal of electrocardiology, 47(1), 75-79.
Co, I., Eilbert, W., & Chiganos, T. (2017). New Electrocardiographic Changes in Patients Diagnosed with Pulmonary Embolism. Journal of Emergency Medicine, 52(3), 280-285
Cygan, L. D., Weizberg, M., & Hahn, B. (2016). Spontaneous, resolving S1Q3T3 in pulmonary embolism: A case report and literature review on prognostic value of electrocardiography score for pulmonary embolism. International emergency nursing, 28, 46.
Konstantinides, S. V., Torbicki, A., Agnelli, G., Danchin, N., Fitzmaurice, D., ... & Kucher, N. (2014). 2014 ESC Guidelines on the diagnosis and management of acute pulmonary embolism: The Task Force for the Diagnosis and Management of Acute Pulmonary Embolism of the European Society of Cardiology (ESC) Endorsed by the European Respiratory Society (ERS). European heart journal, 35(43), 3033-3073.
Qaddoura, A., Digby, G. C., Kabali, C., Kukla, P., Zhan, Z. Q., & Baranchuk, A. M. (2017). The value of electrocardiography in prognosticating clinical deterioration and mortality in acute pulmonary embolism: A systematic review and meta‐analysis. Clinical cardiology.
Raghav, K. P., Makkuni, P., & Figueredo, V. M. (2011). A review of electrocardiography in pulmonary embolism: recognizing pulmonary embolus masquerading as ST-elevation myocardial infarction. Rev Cardiovasc Med, 12(3), 157-163.
Rawal, G., Yadav, S., Kumar, R., & Sujana, R. (2017). ECG as diagnostic tool for pulmonary embolism: A case report. Indian Journal of Immunology and Respiratory Medicine, 2(4), 111-112.
Zhan, Z. Q., Wang, C. Q., Nikus, K. C., He, C. R., Wang, J., Mao, S., & Dong, X. J. (2014). Electrocardiogram patterns during hemodynamic instability in patients with acute pulmonary embolism. Annals of noninvasive electrocardiology, 19(6), 543-551.