The incidence of pulmonary embolism in unexplained sudden cardiac arrest with pulseless electrical activity.

PURPOSE: 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. SUBJECTS AND 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.

Comparison of naive sixth-grade children with trained professionals in the use of an automated external defibrillator.

BACKGROUND: Survival after out-of-hospital cardiac arrest (OHCA) is strongly influenced by time to defibrillation. Wider availability of automated external defibrillators (AEDs) may decrease response times but only with increased lay use. Consequently, this study endeavored to improve our understanding of AED use in naive users by measuring times to shock and appropriateness of pad location. We chose sixth-grade students to simulate an extreme circumstance of unfamiliarity with the problem of OHCA and defibrillation. The children's AED use was then compared with that of professionals. METHODS AND RESULTS: With the use of a mock cardiac arrest scenario, AED use by 15 children was compared with that of 22 emergency medical technicians (EMTs) or paramedics. The primary end point was time from entry onto the cardiac arrest scene to delivery of the shock into simulated ventricular fibrillation. The secondary end point was appropriateness of pad placement. All subject performances were videotaped to assess safety of use and compliance with AED prompts to remain clear of the mannequin during shock delivery. Mean time to defibrillation was 90+/-14 seconds (range, 69 to 111 seconds) for the children and 67+/-10 seconds (range, 50 to 87 seconds) for the EMTs/paramedics (P<0.0001). Electrode pad placement was appropriate for all subjects. All remained clear of the "patient" during shock delivery. CONCLUSIONS: During mock cardiac arrest, the speed of AED use by untrained children is only modestly slower than that of professionals. The difference between the groups is surprisingly small, considering the naïveté of the children as untutored first-time users. These findings suggest that widespread use of AEDs will require only modest training.

Transesophageal echocardiographic assessment of embolic sources: intracardiac and extracardiac masses and aortic degenerative disease.

The increased sensitivity of transesophageal echocardiography (TEE) makes it complementary and, in many cases, superior to transthoracic echocardiography in the detection of various sources of embolism. These sources include intracardiac thrombus, tumors, spontaneous echocardiographic contrast, and others. TEE is also helpful as an adjunctive test for the diagnosis of pulmonary embolisms.

Low yield of clinically significant transesophageal echocardiographic findings in patients with lacunar stroke.

Transesophageal echocardiography (TEE) is a sensitive technique for the detection of cardioembolic sources of stroke in patients with cryptogenic stroke. However, the yield of clinically significant TEE-detected abnormalities in other stroke subtypes such as lacunar stroke is unknown. We prospectively followed 145 consecutive stroke patients, including 26 patients with typical lacunar syndromes, to determine the relative risk of recurrent brain ischemia associated with TEE findings. The yield of TEE in patients with lacunar stroke syndromes was extremely low, except for a very high rate of atrial septal aneurysm (ASA). Although ASA was associated with a high risk of recurrent stroke or transient ischemic attack in patients with nonlacunar stroke, ASA was not associated with stroke recurrence in patients with lacunar stroke (p = 0.02, Cox's proportional hazard regression model). We conclude that TEE is unlikely to provide clinically relevant information in patients with typical lacunar syndromes.

Transesophageal echocardiography and carotid ultrasound in patients with cerebral ischemia: prevalence of findings and recurrent stroke risk.

OBJECTIVES: This study was conducted to determine the yield of transesophageal echocardiographic findings in a consecutive series of patients with stroke and transient ischemic attack, with and without carotid stenosis, and to estimate the recurrent stroke risk associated with specific echocardiographic findings. BACKGROUND: Transesophageal echocardiography has a high yield for identification of potential sources of cardiac embolism in patients with cerebral ischemia; however, the clinical significance of the most commonly detected abnormalities is uncertain. METHODS: We evaluated 145 consecutively admitted patients with stroke or transient ischemic attack with both transesophageal echocardiography and carotid ultrasound. Patients were followed up prospectively for a mean duration of 18 months to document the rate of recurrent cerebral ischemia. RESULTS: Transesophageal echocardiography detected at least one potential cardiac source of embolism in 45% of the patients. Atrial septal aneurysm and interatrial shunt were detected more frequently in patients who did not have a significant carotid stenosis that could account for their ischemic event. During follow-up, a higher rate of recurrent stroke or transient ischemic attack occurred in patients with positive transesophageal echocardiographic findings, particularly atrial septal aneurysm, interatrial shunt and left atrial thrombus. CONCLUSIONS: These data support recent studies that suggest that atrial septal aneurysm and interatrial shunts may be a significant source of cardioembolic stroke. Further studies are needed to clarify the optimal management of patients with these abnormalities.

Transesophageal echocardiographic findings in stroke subtypes.

BACKGROUND AND PURPOSE: Transesophageal echocardiography has a high yield for detecting potential cardiac sources of embolism in patients with clinical risk factors for cardioembolism or unexplained stroke. The yield in other stroke subtypes is unknown. METHODS: We classified 145 consecutively admitted patients into stroke subtypes based on clinical findings, brain imaging, and carotid ultrasound. Both transesophageal and transthoracic echocardiography were performed to detect left atrial thrombi, spontaneous echo contrast, atrial septal aneurysm, interatrial shunts, ventricular thrombus or aneurysm, and myxomatous mitral valve. RESULTS: Transesophageal echocardiography documented at least one of these findings in 46% of the patients compared with an 8% yield on the transthoracic study (P = .002). The yield of transesophageal echocardiography was substantial in all stroke subgroups. Patients with clinical risk factors for cardiac embolism had the highest frequency of spontaneous echo contrast (P = .001). Atrial septal aneurysms were most frequent in patients with lacunar syndromes (P = .012), and interatrial shunts were common in all stroke subtypes. CONCLUSIONS: Transesophageal echocardiographic findings vary considerably between stroke subgroups.

Transesophageal echocardiography in the evaluation of stroke.

OBJECTIVE: To review the current role of transesophageal echocardiography in the evaluation of stroke. DATA IDENTIFICATION: Articles examining the role of transesophageal echocardiography for evaluation of patients with stroke were identified using computer and bibliography searches. STUDY SELECTION: All English-language articles that provided full details on patient selection criteria, methods, and study design were reviewed. RESULTS OF DATA ANALYSIS: Cardiogenic embolism is frequently an uncertain diagnosis merely inferred by finding a potential cardiac source. Transthoracic echocardiography has had a low yield in screening unselected patients with stroke. Several series of patients with stroke have been reported comparing transthoracic and transesophageal echocardiography. Potential cardiac sources of embolism were consistently identified in many more patients by transesophageal echocardiography. Many findings are, however, of uncertain significance; these include spontaneous echo contrast, patent foramen ovale, filamentous strands on the mitral valve, and atrial septal aneurysm. CONCLUSIONS: Transesophageal echocardiography is most helpful in patients with stroke who are less than 45 years of age and in those without clinical evidence of heart disease. The indications for its use in the evaluation of stroke remain controversial. Further studies are needed using transesophageal echocardiography in patients with stroke and in control groups, not only to determine the natural history of transesophageal, echocardiographically detected abnormalities but also to evaluate treatment options.

Failure of high-dose heparin to prevent recurrent cardioembolic strokes in a pregnant patient with a mechanical heart valve.

A 27-year-old woman with a mechanical heart valve suffered multiple thromboembolic events while pregnant despite anticoagulation with high-dose heparin. Warfarin, the anti-coagulant of choice for patients with prosthetic heart valves, is teratogenic and can cause hemorrhagic complications at delivery. Heparin reduces thromboembolic complications, but is of uncertain efficacy. We discuss alternatives for the prevention of thromboembolic complications in pregnant women with mechanical heart valves.