title: The incidence of pulmonary embolism in unexplained sudden cardiac arrest with pulseless electrical activity.
abstract: OBJECTIVE
  The cause of many cases of sudden cardiac arrest from pulseless electrical activity is unknown. We hypothesized that pulmonary embolism was responsible for a substantial proportion of these cases and used transesophageal echocardiography to identify pulmonary embolism among patients with sudden cardiac arrest.
  
  
  METHODS
  We performed a prospective study at a tertiary care, university-operated county hospital, with a level 1 trauma center. Consecutive patients (n = 36) who were admitted with (n = 20) or unexpectedly developed (n = 16) sudden cardiac arrest of unknown cause were studied with transesophageal echocardiography during cardiopulmonary resuscitation. We determined the presence of central pulmonary embolism, right ventricular enlargement, and other causes of sudden cardiac arrest (such as myocardial infarction and aortic dissection) using prospectively defined criteria.
  
  
  RESULTS
  Of the 25 patients with pulseless electrical activity as the initial event, 9 (36%) had pulmonary emboli (8 seen with transesophageal echocardiography and 1 diagnosed at autopsy) compared with none of the 11 patients with other rhythms, such as asystole or ventricular tachycardia or fibrillation (P = 0.02). Of the 8 patients who had pulmonary embolism diagnosed by transesophageal echocardiography, 2 survived to hospital discharge.
  
  
  CONCLUSIONS
  Mortality from massive pulmonary embolism is high, particularly if patients present with sudden cardiac arrest. Earlier diagnosis of pulmonary embolus may permit wider use of thrombolytic agents or other interventions and may potentially increase survival.
authors.affiliation: Department of Internal Medicine/Cardiology Division, Harborview Medical Center and University of Washington, Seattle, Washington, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Comess
authors.forename: F A
authors.initials: FA
authors.lastname: DeRook
authors.forename: M L
authors.initials: ML
authors.lastname: Russell
authors.forename: T A
authors.initials: TA
authors.lastname: Tognazzi-Evans
authors.forename: K W
authors.initials: KW
authors.lastname: Beach
mesh_terms: D000368:Aged; D016887:Cardiopulmonary Resuscitation; D003937:Diagnosis, Differential; D017548:Echocardiography, Transesophageal; D004562:Electrocardiography; D005260:Female; D006323:Heart Arrest / Q000000981:diagnostic imaging* / Q000209:etiology* / Q000628:therapy; D006785:Hospitals, University; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015205:Northwestern United States / Q000453:epidemiology; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000150:complications* / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000401:mortality; D011674:Pulse