One of the more formidable complications, albeit infrequent, that can occur following open heart surgery is postcardiotomy shock (PCS), which is associated with an in-hospital mortality rate of more than 60 percent. In the past decade, venoarterial extracorporeal membrane oxygenation (VA-ECMO) has emerged as a viable method for managing PCS when patients are unable to be weaned from cardiopulmonary bypass or for those needing high-dose vasoactive support with signs of decreasing end-organ perfusion. However, while it is potentially lifesaving for these patients, ECMO can also have severe consequences such as bleeding and thrombotic events.
One of the more formidable complications, albeit infrequent, that can occur following open heart surgery is postcardiotomy shock (PCS), which is associated with an in-hospital mortality rate of more than 60 percent. In the past decade, venoarterial extracorporeal membrane oxygenation (VA-ECMO) has emerged as a viable method for managing PCS when patients are unable to be weaned from cardiopulmonary bypass or for those needing high-dose vasoactive support with signs of decreasing end-organ perfusion. However, while it is potentially lifesaving for these patients, ECMO can also have severe consequences such as bleeding and thrombotic events.
Approximately 15 years ago, NewYork-Presbyterian and Columbia began using VA-ECMO therapy for patients with postcardiotomy shock. “Early on, the decision to use ECMO management in these patients was at the discretion of the surgeon,” says Koji Takeda, MD, PhD, Surgical Director of Heart Transplant and Mechanical Circulatory Support for the Division of Cardiothoracic and Vascular Surgery at NewYork-Presbyterian/
Despite the increased use of ECMO for PCS, guidelines on when to initiate ECMO, cannulation strategy, and management protocols across ECMO centers did not exist and mortality rates remained high. Taking this into account, Dr. Takeda and the team of ECMO specialists at NewYork-Presbyterian/
Dr. Koji Takeda
Evidence for Initiating ECMO Earlier
In a retrospective study of 156 consecutive patients who underwent VA-ECMO for PCS between 2007 and 2018, the Columbia team examined patient characteristics, indications, and management to determine factors affecting outcomes. The team’s findings, published in the March 2021 issue of the Journal of Artificial Organs, demonstrated that initiating ECMO earlier appears to be associated with a survival benefit and fewer complications over time. Specifically, the research revealed:
- In-hospital mortality of 53.8 percent (84 patients)
- Survivors were less likely to have coronary artery disease and trended toward lower preoperative creatinine
- Survivors cannulated at a lower serum lactate and at a lower vasoactive-inotropic score had improved lactate clearance over 12 hours; the observed association of elevated lactate and vasoactive-inotropic score with mortality supports an early approach toward ECMO initiation
- Survival to discharge steadily increased during the study period; of the entire cohort, 40.4 percent (63 patients) were discharged with full myocardial recovery
Understanding the Challenge of Anticoagulation Therapy
A supplementary analysis involving the above patient cohort undertaken by a NewYork-Presbyterian/
Notably, studies have shown that patients who develop postcardiotomy shock are at high risk for both of these complications due to derangements in coagulation associated with cardiac surgery, hemostatic disruptions related to cardiopulmonary bypass, as well as the use of ECMO. For thrombosis, there is evidence that other risk factors may involve obesity, a high transfusion burden, hemodialysis, increased time on ECMO, and a decreased activated partial thromboplastin time (aPTT). At the same time, there is some evidence pointing to a reduced need for anticoagulation therapy for patients who undergo ECMO due to advancements in its technology.
The investigation by the Columbia faculty drew subjects from 152 patients who received ECMO for postcardiotomy shock at NewYork-Presbyterian/
The researchers classified bleeding events using the ELSO definition:
- Bleeding requiring two units of packed red blood cells in 24 hours
- Bleeding requiring intervention
- Bleeding accompanied by a hemoglobin drop of 2 g/dL in 24 hours
They also included intrapericardial hemorrhage, hemothorax, and retroperitoneal bleeding in their analysis.
Thrombotic events included:
- Limb ischemia
- Intracardiac thrombosis
- Deep vein thrombosis
- Pulmonary embolism
- Circuit thrombosis
- Ischemic stroke
- Other arterial system thrombosis
Their objective was to determine the effect of and provide insight on how to best manage anticoagulation therapy in these patients. The study’s findings, published in the January 2022 issue of The Annals of Thoracic Surgery, showed:
- 40 thrombotic events occurred in 33 patients (23 percent), including intracardiac thrombosis (35 percent of cases) and circuit clots (23 percent of cases)
- In 9 patients who had prosthetic valve thrombosis, 6 received anticoagulation therapy, 2 had valve replacements, and 1 had a thrombectomy
- 64 patients (45 percent) had 86 bleeding events, most commonly postoperative bleeding (36 percent of bleeding events)
The authors note that the study provides further evidence that patients with postcardiotomy shock are at increased risk of bleeding. They further state, “the use of anticoagulation therapy is beneficial for thrombosis prophylaxis in PCS patients on ECMO, although at aPTTs greater than 60 seconds the increased bleeding risk may outweigh this benefit.”
“To overcome these historical challenges, we created institutional protocols and a specialized team-based approach to optimize the use of ECMO in the management of PCS,” says Dr. Takeda.
Standardizing ECMO Management
To determine the influence of their formalized protocol and dedicated multispecialty team, the Columbia faculty then undertook a study to determine if standardizing ECMO management influences patient outcomes.
Our study proved that implementing a standardized protocol and dedicated multidisciplinary team improved outcomes for PCS patients on ECMO, with the rate of patients surviving to hospital discharge approaching 70 percent following ECMO treatment for postoperative cardiotomy shock.
— Dr. Koji Takeda
The Columbia protocol for PCS patients during the study period included:
- Use of dobutamine, milrinone, epinephrine, norepinephrine, and vasopressin for hemodynamic support
- Requirement of 2 high-dose inotropes and/or 2 high-dose vasopressors to trigger initiation of ECMO
- Preference for femoral access to allow for early chest closure, to more readily permit extubation, and to facilitate decannulation without chest reopening
- Selection of central cannulation, which is associated with increased morbidity and mortality, if patients develop severe hypoxia due to acute lung injury, require open chest due to significant bleeding, have severe peripheral vasculopathy, or require significant hemodynamic support that would not be possible with a partial flow strategy
- Potential application of partial flow strategy (60 to 80 percent of total cardiac output) to facilitate aortic valve opening, particularly important in patients with prosthetic valves to prevent prosthetic valve thrombosis
- Fully reversing heparin intraoperatively with administration of protamine and rarely starting anticoagulation within 24 hours postoperatively
- Generally limiting ECMO support to 7 days based on anecdotal experience of increasing risk of complications with prolonged support
The NewYork-Presbyterian/
The team also advocated for early institution of ECMO before signs of irreversible organ failure. Contraindications to ECMO support included acute postoperative stroke or existing multiorgan failure.
Specifically, the Columbia team evaluated in-hospital mortality as the primary outcome and ECMO-related complications as the secondary outcome. Eighty percent of patients received peripheral ECMO, and 20 percent were centrally cannulated. The findings of their observational study, published in the October 1, 2021, issue of the ASAIO Journal, showed:
- In-hospital mortality and 30 day mortality were 33.3 percent and 22 percent, respectively
- Overall, 40 patients (67 percent) survived to hospital discharge
- Median duration of ECMO support was 5 days
- Major adverse events included chest re-exploration (15 percent), stroke (6.7 percent), renal replacement therapy (22 percent), and limb ischemia (5 percent)
- 50 patients (83 percent) were successfully weaned from ECMO support
- Outcomes were similar regardless of whether cannulation was in the operating room or intensive care unit
The Columbia team also reviewed data from PCS patients at NewYork-Presbyterian/
The study authors conclude, “The institution of a standardized team-based approach led to favorable outcomes in patients with PCS requiring veno-arterial ECMO. Our approach emphasizes early institution of ECMO, peripheral cannulation, partial ECMO blood flow, pulmonary artery catheter-guided postoperative management, and conservative use of intravenous unfractionated heparin.”
Recognized for Excellence in ECMO
NewYork-Presbyterian/
Over the years, NewYork-Presbyterian’s ECMO programs have generated important contributions to the application of ECMO for the treatment of patients with severe respiratory failure, cardiogenic shock, and those awaiting heart or lung transplant.
