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In this episode, Dr. Carly Fabrizio (Advanced Heart Failure and Transplant Cardiology Physician at Christiana Care Hospital), CardioNerds Critical Care Series Co-Chair Dr. Mark Belkin (Advanced Heart Failure and Transplant Fellow at University of Chicago) and CardioNerds Co-Founder Dr. Amit Goyal (Cleveland Clinic) join Dr. Gavin Hickey (Director of the AHFTC Fellowship and medical director of the left ventricular assist device program at UPMC) and Dr. David Kaczorowski (Surgical Director for the Advanced Heart Failure center, Department of Cardiothoracic Surgery at UPMC) for a discussion on post-cardiotomy shock. Audio editing by CardioNerds Academy Intern, student doctor, Shivani Reddy.

Post-cardiotomy shock is characterized by heart failure that results in the inability to wean from cardiopulmonary bypass or develops post cardiac surgery. Patients who develop post-cardiotomy shock typically require inotropic support and may ultimately require temporary mechanical circulatory support. Post-cardiotomy shock carries a high mortality rate. However, early recognition and prevention strategies can help mitigate the risk for developing post-cardiotomy shock.

The CardioNerds Cardiac Critical Care Series is a multi-institutional collaboration made possible by contributions of stellar fellow leads and expert faculty from several programs, led by series co-chairs, Dr. Mark Belkin, Dr. Eunice Dugan, Dr. Karan Desai, and Dr. Yoav Karpenshif.

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Pearls • Notes • References • Production Team

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Pearls and Quotes – Post-cardiotomy Shock

• Weaning from cardiopulmonary bypass is an intricate process that includes: rewarming the patient, de-airing the cardiac chambers, ensuring a perfusing heart rhythm, confirming adequate ventilation and oxygenation, removing the intracardiac catheters and cannulas and slowly reducing the blood diverted to the cardiopulmonary circuit and returning it small aliquots to the patient. Much to monitor during the process!

• Assessing the risk for post-cardiotomy shock prior to going to the OR is important. Consider left ventricular, right ventricular, and valvular function, and don’t forget about the value of hemodynamic assessments (pulmonary artery catheter evaluations) to ensure patients are adequately compensated.

• Close peri-operative monitoring of hemodynamics, hemo-metabolic derangements, and acid/base status can help identify patients who are failing therapy and may require upgrade to temporary MCS.

• RV assessment is challenging. Utilizing both imaging and hemodynamic evaluations can help understand which RV’s will require more support.

• Multi-disciplinary discussions with a heart team approach prior to cardiac surgery are valuable in identifying high risk patients for post cardiotomy shock and discussing contingency plans if issues arise.

Show notes – Post-cardiotomy Shock

(drafted by Dr. Carly Fabrizio)

1. How can we diagnose post cardiotomy shock?
   • We can diagnose post cardiotomy shock as patients who are undergoing cardiac surgery that develop hypotension and or tachycardia with hypoperfusion and end organ dysfunction.

• How can assess the risk of developing postcardiotomy shock prior to going to the OR?
  • LV systolic function is not the only evaluation of cardiac function
  • Don’t ignore the RV!
  • Valvular function must be evaluated in conjunction with LV/RV function
  • Hemodynamics can be helpful prior to going to the OR
    • Filling pressures and CO/CI evaluation –> the more normal range – the less risk of post cardiotomy shock
    • If going in more deranged –> more complications are likely to occur
  • Think about what options are available post operatively if issues arise
    • Include a multi-disciplinary discussions and planning prior to going to the OR

• Are there any specific pre-operative or intra-operative risk factors that may predispose someone to developing post cardiotomy shock?
  • Many factors can lead to postcardiotomy shock. Some pre-op factors include:
    • Poor pre-operative cardiac function (RV and /or LV function)
    • Entering the OR in cardiogenic shock (inotropes, temporary MCS)
    • Well compensated patients with chronic ventricular dysfunction
  • Intra-operative factors:
    • Prolonged cross-clamp time
    • Prolonged cardiopulmonary bypass (CPB) times (often seen in complex operations)
    • Inadequate myocardial protection
    • Ventricular distention
    • Technical factors

• What is actually occurring in the OR when weaning from CPB?
  • After the aorta cross clamp is removed- the heart is allowed to re-perfuse
    • Remember that the heart has been ischemic for a considerable amount of time
  • Lungs are re-inflated
  • Temporary atrial and ventricular pacing wires are placed
  • Stable rhythm is achieved and the heart is paced if necessary
  • Acid / base status and electrolytes (potassium) are optimized
  • Once the heart is de-aired, CPB is gradually weaned
    • The flow of the CPB circuit is gradually reduced and more of the patient’s blood volume is gradually allowed to pass through the heart and lungs
  • TEE is performed while weaning bypass
  • Once bypass is completely weaned, the cannulas used to establish CPB are removed
  • Anticoagulation is reversed
  • Assess for hemostasis
  • Chest tubes are placed, and closure occurs

• What are the clinical and laboratory parameters which help determine whether vasoactive support alone will be enough vs. when temporary MCS may be needed?
  • Assess perfusion first
    • BP
    • Urine output
    • Lactic acid
  • PA catheter data /  hemodynamic data
    • Cardiac output/index (CO/CI)
    • Pulmonary artery pressures (PAP)
    • Central venous pressures (CVP)
    • Mixed venous oxygen saturation
    • Cardiac power output (CPO) and cardiac power index (CPI)
      • CPO < 0.6 or CPI < 0.32 are considered low
  • Serial blood gas
    • Focus on pH and bicarbonate (acid/base status)
  • Optimize inotropic support accordingly
    • Favor epinephrine in safe dosing limits and minimizing drugs that increase afterload whenever possible
    • Consider Milrinone if the blood pressure is adequate
  • If pulmonary hypertension
    • Inhaled nitric oxide or inhaled prostacyclin
  • If worsening despite these measures –> consider escalation to temporary MCS

• Left ventricular assist devices (LVAD) do not support the right ventricle. How can we identify RV failure in these patients and when should you upgrade to RV mechanical circulatory support?
  • Most patient that require left-sided support by nature often have underlying right-sided dysfunction as well
  • Pre-operative – assessment of the RV is important:
    • CVP
    • PAPi (PA systolic pressure- PA diastolic pressure / CVP)
    • CVP: PCWP ratio
  • RV failure can occur in any patient
    • No great, reliable, and reproducible data on when or how to support the RV following LVAD implantation, or cardiogenic shock in general. More studies are needed.

• What’s different about how you assess the RV dysfunction in the OR compared to someone who is in the ICU? When do you consider using RV mechanical support upfront in the OR?
  • Intra-operative TEE and direct visualization are both used in the OR to assess RV function
  • Try to avoid upfront RV mechanical support in the OR
    • Optimize with invasive hemodynamic monitoring prior to OR
      • Temporary MCS can be used to optimize patient and help with diuresis pre-operatively
  • Continue to optimize the RV while in the OR
    • Remove volume through hemoconcentration while on CPB circuit to optimize volume status
  • Consider temporary MCS for the RV when medical therapy is maximized, and the patient still remains marginal as measured by:
    • LVAD flows, cardiac output/index, mixed venous gases and metabolic parameters

• Are there any surgical consideration to influence the type of temporary MCS for postcardiotomy shock?
  • Strategize first by asking:
    • What is failing? LV, RV, lungs, or a combination
    • What access is available?
  • Ex: Bi-ventricular failure with hypoxemia and peripheral arterial disease: consider central VA ECMO
  • Ex: Pure LV failure but RV and lungs OK –> temporary LV assist device

• How can we prevent, or decrease the risk, of post-cardiotomy shock ?
  • Optimized hemodynamics going into the OR using a PA catheter
  • Multi-disciplinary discussion with cardiac anesthesia, critical care team, etc. for high-risk cases
  • Ensure adequate end-organ perfusion
  • Avoid pre-operative medications that worsen peri-operative vasoplegia
    • ACE-i/ARB/ARNI, milrinone etc.

1. What is role of advanced therapy evaluations when assessing high risk patients going to the OR?
   • Important to think about options pre-operatively
     • Selection committee discussions to weigh-in on candidacy for LVAD or cardiac transplant and if that may be more beneficial than other cardiac surgical interventions

1. How does team-based care help with decision making?
   • Optimize patients pre procedure and support them peri-procedure
   • Involving palliative care team and establishing patient goals prior to surgery

References – Post-cardiotomy Shock

1. Lorusso, Raffa, Alenizy, et al. “Structured review of post-cardiotomy extracorporeal membrane oxygenation: part 1—Adult patients.” JHLT. 38(11): 1125-1143. 2019.https://www.sciencedirect.com/science/article/pii/S1053249819316328
   
2. Fukuhara, Takea, Garan, et al. “Contemporary mechanical circulatory support therapy for postcardiotomy shock.” Curr Topics Review Article. 64:183-191. 2016. https://link.springer.com/content/pdf/10.1007/s11748-016-0625-4.pdf

CardioNerds Cardiac Critical Care Production Team