CARDIOLOGY/CASE REPORT Systemic Fibrinolysis Through Intraosseous Vascular Access in ST-Segment Elevation Myocardial Infarction Pedro José Ruiz-Hornillos, RN, Fernando Martínez-Cámara, MD, Mercedes Elizondo, RN, José Antonio Jiménez-Fraile, MD, Maria del Mar Alonso-Sánchez, RN, Dolores Galán, RN, Juan Carlos García-Rubira, MD, PhD, Carlos Macaya, MD, PhD, Borja Ibanez, MD, PhD From the Servicio de Asistencia Municipal de Urgencia y Rescate, Madrid, Spain (Ruiz-Hornillos, Martínez-Cámara, Elizondo, Jiménez-Fraile, Alonso-Sánchez, Galán); the Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain (García-Rubira, Macaya, Ibanez); and the Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain (Ibanez). In emergency situations, intraosseous cannulation represents an alternative route of vascular access when peripheral vein insertion is difficult. We present the first documented case of intraosseous systemic fibrinolysis in a patient with ST-segment elevation myocardial infarction. In this case, repetitive episodes of ventricular fibrillation occurred soon after first contact with emergency care providers. Given that the patient had difficult peripheral venous access, an intraosseous catheter was inserted. Fibrinolytics and antiarrhythmic drugs were administered though this line, resulting in resolution of coronary ischemia and electrical instability, without complications. Intraosseous cannulation represents a novel route for administration of systemic fibrinolysis in cases of difficult peripheral venous access in the out-of-hospital setting. [Ann Emerg Med. 2011;57:572-574.] 0196-0644/$-see front matter Copyright © 2010 by the American College of Emergency Physicians. doi:10.1016/j.annemergmed.2010.09.011 INTRODUCTION Pharmacologic reperfusion (fibrinolysis) is an effective intervention for patients experiencing an ST-segment elevation myocardial infarction (STEMI). The benefits of fibrinolytic therapy are maximal when it is initiated early after the onset of coronary occlusion. Primary ventricular fibrillation is common during the initial hours of a STEMI. 1 Even though early defibrillation is usually effective in treating this lethal STEMI- related complication, repetitive episodes of ventricular fibrillation might occur during ongoing ischemia. In such cases, the systemic administration of antiarrhythmic drugs and early coronary reperfusion are the only treatments capable of reducing electrical instability. Here we present the case of a patient with a STEMI and repetitive episodes of ventricular fibrillation, with no peripheral vein access, in which drug administration was conducted by intraosseous access. To the best of our knowledge, this is the first documented report of systemic fibrinolysis administered by intraosseous vascular access in a STEMI patient. CASE REPORT A 64-year-old man with a history of untreated hypertension, diabetes mellitus (diet controlled), and no other cardiovascular disease called the emergency medical system after 30 minutes of chest pain, associated with nausea and dizziness. Five minutes later, health care providers from our emergency medical system (Servicio de Asistencia Municipal de Urgencia y Rescate [SAMUR]) arrived at the patient’s location. The patient’s initial vital signs were as follows: blood pressure 170/100 mm Hg, pulse rate 80 beats/min, oxygen saturation 98%. The 12-lead ECG (Figure, A) showed sinus rhythm, right bundle branch block, ST-segment elevation in the inferior leads and in V1 through V6, and ST-segment depression in I and aVL. Peripheral vein access was not obtained after several attempts during patient transfer to the hospital. Continuous ECG monitoring then showed ventricular fibrillation, followed by loss of consciousness. A biphasic shock (150 J) was delivered, resulting in restoration of sinus rhythm with persistent ST-segment elevation. During the following minutes, several episodes of ventricular fibrillation were documented, all of which were reversed by biphasic shock therapy. Given the life-threatening situation, and following clinical guidelines, 2 SAMUR health care providers decided to place an adult-sized intraosseous line (EZ-IO; Vidacare, San Antonio, TX) for drug delivery in the proximal tibia. The access was achieved in less than a minute (Figure, B). A blood sample was collected, and weight-adjusted fibrinolytic therapy was immediately delivered through the intraosseous line (6,000 IU of tenecteplase as a bolus), followed by 3,000 IU of unfractionated heparin as a bolus. Subsequently, an infusion of amiodarone (300 mg in a 100-mL 5% dextrose minibag, during 20 minutes) was administered through this vascular route for shock-refractory ventricular fibrillation. Electrical instability was reduced, with a few ventricular couple complexes and a single run of nonsustained ventricular tachycardia documented thereafter. Oral aspirin was administered at this time. Thirty minutes after fibrinolytic administration, reperfusion dysrhythmias were documented, with normalization of 572 Annals of Emergency Medicine Volume , .  : June 