1. clinical data
Case 1: a 45-year-old male experienced retrosternal compression pain with radiation to the back, and then lost consciousness. Immediately, the patient was performed chest compressions and transported to our emergency room by ambulance. The patient had any conventional cardiovascular risk factor (smoking, high cholesterol and obese). A physical exam showed an unconsciousness, disappearance of aortic fluctuations and unresponsive dilated pupils, and then advanced cardiovascular life support continued. Electrocardiogram showed ST-segment over the extensive frontal wall (V1-V5); And biochemical indices (CK-MB, TnI) was in accordance with acute myocardial infarction. After 45 min of cardiac massage, return of spontaneous circulation (ROSC) occurred. The patient needed vasoactive therapy and expansive fluid volume substitution in post cardiac arrest syndrome after transfer to our department. After evaluation, he was connected to VA-ECMO (Femoro-femoral) within 45 min in the ward upon arrival. Furthermore, mild therapeutic hypothermia (34–36℃) was applied to the patient. Within the first day, the clinic status of patient ameliorated significantly with improvement of blood pressure. And then the blood lactate level gradually decreased. VA-ECMO was successfully weaned on hospital day 3. The patient’s cardiovascular status remained stable and he was pain-free. On hospital 10 days, he was transferred to department of cardiology and discharged after 15 days in hospital.
Case 2: a 58-year-old woman, admitted to hospital with a chief complaint of " Palpitation, syncope ". she had a medical history of diabetes mellitus, hypertension, and documented implant of drug stent in the right coronary artery. In addition, ICD was implanted due to reduced left ventricular function (LVEF 35%). Vital signs and lung examination was normal. Heart auscultation revealed a regular cardiac rhythm with murmurs. ECG showed sinus tachycardia accompanied occasional premature ventricular beats. During hospitalization, she had a recurrent ventricular arrhythmic (ventricular arrhythmia storms) and required electrical defibrillations, even injected anti-arrhythmic drugs ( amiodarone, propatonone, and lidocaine). In addition, her blood pressure needed to be maintained by norepinephrine intravenously. Thus, she underwent intubation. At present, with hypotensive, ventricular arrhythmia, and hypoxic, it was necessary to perform coronary angiography. As a bridge-therapy, VA-ECMO support was implanted, and then she was taken to the cardiac catheterization laboratory and implanted a drug-eluting stent in the right coronary artery due to totally occlusion of proximal right coronary artery. Continuous renal replacement therapy (CRRT) was attributed to acute renal failure. Accompanied with normalization of conduction and improvement of blood pressure, the clinic status ameliorated. After evaluation, VA-ECMO was weaned successfully on hospital day 5. On day 16, the patient was transferred to the Department of Cardiology and discharged after 30 days in hospital.
2. ECMO Management
(1) The use of VA-ECMO was based on the following criteria: refractory cardiogenic shock in the setting of maximum inotropic support (dobutamine > 15 mg/kg/min with norepinephrine > 0.2 mg/kg/min); recurrent of witnessed cardiac arrest with successful cardiopulmonary resuscitation; (2) Before cannulation, a prophylactically 6-Fr catheter (TERUMO 6Fr, Radifocus, Inc., Japan) were implanted to ensure the anterograde perfusion of lower extremities and the cannulas were strengthened with reinforced purse-string sutures; (3) A continuously intravenous heparin was administrated to achieve an activated partial thromboplastin time (50-70s); (4) During VA-ECMO support, a protective lung ventilation strategy established with a plateau pressure of less than 25cmH2O and/or a maximum PEEP of 12 cmH2O [2]; (5) Bedside transthoracic ultrasound was performed daily to evaluate aortic valve opening, biventricular function, right ventricular unloading and left ventricular distension, and inferior vena cava; (6) The weaning criteria include: LVEF ≥ 35% with an aortic time–velocity integral > 10 cm, absence of left heart distension, ScvO2 ≥ 70%, blood lactate levels < 1.5 mmol/L, and urine output ≥ 0.5ml/kg/h.