ventricular tachycardia or fibrillation ( vt / vf ) in patients with acute myocardial infarction ( ami ) is associated with a poor prognosis.1 ) despite a better prognosis for early vt / vf compared to late vt / vf , early refractory vt / vf is a serious obstacle for the definitive treatment with primary percutaneous coronary intervention ( pci ) . one of the recent advances in the field of critical care is the extracorporeal life support ( ecls ) system , which is portable , readily applicable and easy to maintain . before its advent , patients with ami complicated by refractory vf / vt before commencing primary pci would rarely survive or recover without ischemic brain damage . such patients are among those who can derive the most benefit from ecls at present . in fact , ecls has well demonstrated its efficacy in treating in - hospital cardiopulmonary arrest and is being used for broader indications then before.2 ) the use of ecls after prolonged cardiopulmonary resuscitation ( cpr ) , a traditional contraindication , is particularly challenging . here , we present two cases of emergency ecls after prolonged cpr for in - hospital cardiac arrest caused by refractory vf in patients with ami waiting for primary pci . a 55-year old man visited the emergency room due to acute ch - est pain . his vital signs were stable but his electrocardiogram ( ecg ) showed st - elevation in leads ii , iii and avf as well as q waves in leads v 1 and 2 ( fig . 1 ) . the patient had a history of repeated amis , for which he had received multiple stents in two different hospitals . despite the higher risk of recurrent cardiovascular events , his compliance seemed poor and he was still a heavy smoker . his current medication included triple antiplatelet therapy , a lipid - lowering agent , a beta - blocker , and an angiotensin - converting enzyme inhibitor . the pain - to - door time was about 30 minutes and the pci team was called after diagnosis of an acute inferior wall st - elevation myocardial infarction ( stemi ) . during the stay in the emergency room , the patient suddenly collapsed from vf . cpr was initiated and repeated shocks at maximum energy were administered . throughout about 30 minutes of conventional cpr , , we decided to implement ecls ( capiox ebs , terumo , tokyo , japan ) . the right femoral vessels were accessed guided by anatomical landmarks and ecls was finally implemented , about 2 hours from the initiation of cpr . with full support , we achieved a flow rate of 4.8 l / min and mean arterial pressure of 70 mm hg , but vf persisted . now the patient could be transferred to the catheterization room to undergo primary pci , without the need for chest compressions for his fibrillating heart . in the catheterization room , the left femoral artery accessed also guided by anatomical landmarks and a coronary angiogram ( cag ) was performed . the right cag revealed one stent in the proximal portion that was totally occluded by a thrombus ( fig . the coronary flow was successfully restored after ballooning , about three hours from the onset of chest pain . we implanted a long drug - eluting stent on the previous stent because the residual stenosis after ballooning was more than 80% ( fig . we finished the procedure by installing an intra - aortic balloon pulsation ( iabp ) catheter to assist recovery . the iabp and ecls could be weaned on the third day and the patient was transferred to general ward on the fourth day . he was discharged with chest wall pain , caused by the cpr , and a large hematoma around the ecls cannula insertion site , which had required a transfusion . vital signs were stable but his ecg showed st - elevation in leads v 1 - 4 and isolated vpc . he had hypertension , hypercholesterolemia and acquired immunodeficiency syndrome , for which he received regular medications including anti - viral agents . the pain - to - door time was about 60 minutes and primary pci was promptly arranged after diagnosis of an acute anterior wall stemi . during transfer to the catheterization room , one run of non - sustained vt appeared which could be suppressed with intravenous lidocane . however , during preparation for the procedure in the catheterization room , a sustained vt developed and turned into vf . we immediately called the ecls team and continued cpr . at about 45 minutes of continuous cpr , normal sinus rhythm spontaneously restored with the implementation of ecls ( capiox ebs , terumo , tokyo , japan ) via the right femoral vessels . restoration of sinus rhythm resulted in a stable patient with a flow rate of 2.5 l / min and mean arterial pressure of 80 mm hg . his right cag showed no significant stenosis , however , the left cag revealed a thrombotic occlusion of proximal left anterior descending coronary artery . coronary flow was successfully restored after ballooning , about two and half hours from the onset of chest pain . we implanted a drug - eluting stent in the culprit lesion with no further complications . he regained full consciousness the same day , in the absence of any neurological deficit . the ecls could be weaned the second day and the patient was transferred to general ward on the third day . finally , he was discharged with no complications except for chest wall pain caused by the cpr . a 55-year old man visited the emergency room due to acute ch - est pain . his vital signs were stable but his electrocardiogram ( ecg ) showed st - elevation in leads ii , iii and avf as well as q waves in leads v 1 and 2 ( fig . 1 ) . the patient had a history of repeated amis , for which he had received multiple stents in two different hospitals . despite the higher risk of recurrent cardiovascular events , his compliance seemed poor and he was still a heavy smoker . his current medication included triple antiplatelet therapy , a lipid - lowering agent , a beta - blocker , and an angiotensin - converting enzyme inhibitor . the pain - to - door time was about 30 minutes and the pci team was called after diagnosis of an acute inferior wall st - elevation myocardial infarction ( stemi ) . during the stay in the emergency room , the patient suddenly collapsed from vf . cpr was initiated and repeated shocks at maximum energy were administered . throughout about 30 minutes of conventional cpr , , we decided to implement ecls ( capiox ebs , terumo , tokyo , japan ) . the right femoral vessels were accessed guided by anatomical landmarks and ecls was finally implemented , about 2 hours from the initiation of cpr . with full support , we achieved a flow rate of 4.8 l / min and mean arterial pressure of 70 mm hg , but vf persisted . now the patient could be transferred to the catheterization room to undergo primary pci , without the need for chest compressions for his fibrillating heart . in the catheterization room , the left femoral artery accessed also guided by anatomical landmarks and a coronary angiogram ( cag ) was performed . the right cag revealed one stent in the proximal portion that was totally occluded by a thrombus ( fig . the coronary flow was successfully restored after ballooning , about three hours from the onset of chest pain . we implanted a long drug - eluting stent on the previous stent because the residual stenosis after ballooning was more than 80% ( fig . we finished the procedure by installing an intra - aortic balloon pulsation ( iabp ) catheter to assist recovery . the iabp and ecls could be weaned on the third day and the patient was transferred to general ward on the fourth day . he was discharged with chest wall pain , caused by the cpr , and a large hematoma around the ecls cannula insertion site , which had required a transfusion . vital signs were stable but his ecg showed st - elevation in leads v 1 - 4 and isolated vpc . he had hypertension , hypercholesterolemia and acquired immunodeficiency syndrome , for which he received regular medications including anti - viral agents . the pain - to - door time was about 60 minutes and primary pci was promptly arranged after diagnosis of an acute anterior wall stemi . during transfer to the catheterization room , one run of non - sustained vt appeared which could be suppressed with intravenous lidocane . however , during preparation for the procedure in the catheterization room , a sustained vt developed and turned into vf . we immediately called the ecls team and continued cpr . at about 45 minutes of continuous cpr , normal sinus rhythm spontaneously restored with the implementation of ecls ( capiox ebs , terumo , tokyo , japan ) via the right femoral vessels . restoration of sinus rhythm resulted in a stable patient with a flow rate of 2.5 l / min and mean arterial pressure of 80 mm hg . his right cag showed no significant stenosis , however , the left cag revealed a thrombotic occlusion of proximal left anterior descending coronary artery . coronary flow was successfully restored after ballooning , about two and half hours from the onset of chest pain . we implanted a drug - eluting stent in the culprit lesion with no further complications . he regained full consciousness the same day , in the absence of any neurological deficit . the ecls could be weaned the second day and the patient was transferred to general ward on the third day . finally , he was discharged with no complications except for chest wall pain caused by the cpr . prolonged cpr ( > 30 minutes ) or unwitnessed cardiac arrest are poor prognostic markers for the implementation of ecls.3 ) according to rhee et al.4 ) the time to ecls for in - hospital arrest or shock patients was 4323 minutes in failed weaning cases versus 258 minutes in successful weaning cases in korea . with this in mind , although the precise impact of cpr duration on predicting survival or neurologic recovery seems to be unclear , our experiences suggest that well organized cpr can protect the major organs , including the brain , for up to 2 hours in witnessed in - hospital cardiac arrest . with advancements in ecls systems , patients with in - hospital arrest more experience with the use of ecls will help define its most appropriate time of deployment . because primary pci ( the treatment of choice for stemi ) is readily available and highly successful in current practice , patients with refractory cardiac arrest are likely candidates for ecls . however , conclusions from our limited experiences should not be generalized to other causes of cardiac arrest . according to recent epidemiological study , sustained vt / vf occurred in 5.7% of acute stemi patients undergoing primary pci , which mostly happened before the end of cardiac catheterization.1 ) although the frequency of refractory cardiac arrest is not well documented , it is a potential threat in all patients with ami . our experience of the past two years suggests refractory vf / vt accounts for about 2.5% of patients with stemi waiting for primary pci ( unpublished data ) . the importance of chest compression during cpr is increasingly emphasized.5 - 8 ) we think the favorable results of our cases are based on the endeavored cpr , conducted with minimal interruption of chest compression . also , the cpr in both cases was fully directed by the same experienced cardiologist . to improve the outcome of ecls , rapid and accurate cannulation of the ecls system is important . in one of our two cases we spent about 90 minutes on ecls implantation , mostly due to difficulty in cannulation of the pulseless vessel without interrupting chest compression this was further complicated by formation of a large hematoma at the cannulation site , requiring a transfusion . we hope our experiences may contribute to improving the prognosis of patients with cardiac arrest .
extracorporeal life support ( ecls ) has well demonstrated its efficacy in treating in - hospital cardiac arrest and is being used for broader indications . 
 however , ecls after prolonged cardiopulmonary resuscitation ( cpr ) has been traditionally contraindicated and is now challenging . here , we introduce two cases of successful ecls after prolonged cpr , resulting in a immediate and full recovery . both these acute st elevation myocardial infarction patients waiting for primary percutaneous coronary intervention ( pci ) suddenly collapsed due to ventricular fibrillation ( vf ) , which was refractory to conventional treatment . 
 after 2 hours of conventional cpr , the ecls had been implemented and primary pci could be performed . 
 subsequent to successful revascularization , the vf was stopped with a single electric shock . in our second case , 
 normal sinus rhythm was spontaneously restored after ecls implementation , which was completed after 45 minutes of conventional resuscitation . 
 both patients made a full neurological recovery on the day of the event and were discharged with only minor complications .