In the United States, 350,000 people suffer an out-of-hospital cardiac arrest (OHCA) and 290,000 people suffer from an in-hospital-cardiac arrest (IHCA) each year. Even with our most advanced care, approximately 90% of people who suffer OHCA die, 80% of people who suffer IHCA die, and many of those who do survive have long -term disability [1]. The direct cost of care for patients who have suffered a cardiac arrest is high as $33B [2]. These costs have consistently increased over the last 15 years, while patient outcomes have only improved marginally.
Current cardiac arrest treatment
Although advanced cardiac life support (ACLS) care is a core component in resuscitation from cardiac arrest, treatment options have remained limited over the last 10 years. Current ACLS algorithms focus on high quality chest compressions, epinephrine, early shocks, and amiodarone for specific arrhythmias. However, recent clinical studies have questioned whether the recommendation for epinephrine should be removed, as it may not improve good neurologic outcomes but only overall survival [3].
For some patients, advanced endovascular techniques can be applied if their cardiac arrest is refractory to standard ACLS treatments. Extracorporeal membrane oxygenation (ECMO) has proven to significantly improve survival with good neurologic outcome in patients presenting with a shockable rhythm [4,5]. Unfortunately, this therapy is limited for those few patients who fall victim to cardiac arrest in close proximity to the handful of centers that are capable of putting patients on ECMO.
Future cardiac arrest treatment with advanced endovascular adjuncts
The concept of resuscitative endovascular balloon occlusion of the aorta (REBOA) as an adjunct to cardiopulmonary resuscitation (CPR) has been studied in animal models for over 20 years [1]. Complete occlusion of the descending thoracic aorta with a balloon catheter rapidly increases blood pressure above the point of occlusion with subsequent increases in the coronary artery perfusion pressure (CaPP) and perfusion to the brain. Any intervention that increases blood flow to the myocardium and brain during CPR will improve the chances of return of spontaneous circulation (ROSC) and neurologic recovery. From a physiology perspective, the REBOA concept is well-grounded. However, it has only recently been employed clinically.
A Norwegian series of 10 OHCA patients treated with REBOA in the prehospital setting demonstrated a high rate (60%) of ROSC despite prolonged downtimes (dispatch to REBOA: 45 minutes) before the REBOA was placed [2]. Yet, while REBOA may help achieve ROSC in the face of incredibly slim odds, this adjunct quickly becomes a liability when ROSC occurs as tissue ischemia below the balloon accumulates and the injured heart must pump against increasing levels of aortic afterload.
This situation is further complicated by the abrupt drops in systemic pressure and electrolyte disturbances that accompany REBOA deflation and restoration of systemic aortic blood flow. The problem of REBOA deflation is highlighted by the two-thirds of the Norwegian patients who achieved ROSC and then subsequently rearrested upon balloon deflation. All patients who rearrested died.
An ongoing clinical study in the United States has noted the same phenomenon of rapid rearrest upon REBOA deflation [3]. Taken together, this translational and clinical data suggests that this cardiac arrest resuscitation technique has promise but must be refined. Despite these limitations in the current technology, additional trials in Europe are underway.
Innovative methods of intra-aortic balloon control to maximize the benefits of aortic occlusion while limiting its downsides are being developed to address a critical gap in ACLS care. Endovascular devices capable of increasing coronary artery perfusion pressure (CaPP) during CPR, improving the chances of ROSC, will be able to transition to dynamic and adaptive partial aortic occlusion to facilitate tenuous weaning from complete occlusion and provide follow-on hemodynamic support in the post-ROSC period of cardiac resuscitation.
References
1. Daley K, Morrison JJ, Sather, J, Hile L. The role of resuscitative endovascular balloon occlusion of the aorta (REBOA) as an adjunct to ACLS in non-traumatic cardiac arrest. Am. J. Emerg. Med. 2017 May;35(5):731-736.
2. Brede JR, Lafrenz T, Klepstad P, Skjaerseth EA, Nordseth T, Sovik E, Kruger AJ. Feasibility of Pre-Hospital Resuscitative Endovascular Balloon Occlusion of the Aorta in Non-Traumatic Out-of-Hospital Cardiac Arrest. J. Am. Heart Assoc. 2019 Nov;8(e0140394).