Chapter 38
Anesthesia for Cardiac Surgery

Cardiac anesthesia is a complex but well-established subspecialty. Coronary artery bypass grafting (CABG) remains one of the most commonly performed surgeries in the United States and serves as a cornerstone of this field. While you may become comfortable managing elective CABG and valve procedures by the end of your rotation, this specialty also spans into far more complex territory: you may get to see heart transplants, pulmonary thromboendarterectomy, and lung transplants for conditions such as cystic fibrosis or patients with WHO Class I pulmonary hypertension. You may also have the opportunity to take care of patients on central or peripheral ECMO.

During this rotation, you will sharpen your skills in procedures, infusion management, large-volume transfusions, and hemodynamic monitoring. You’ll also gain exposure to the perioperative management of patients with implantable cardiac assist devices (e.g., LVADs) and extracorporeal life support (e.g., ECMO). It’s a rotation that will challenge your clinical judgment and attention to detail in life-threatening situations. It will ultimately push you to become a more capable and confident provider.

Getting Started

The night before my first cardiac anesthesia rotation, I read Cardiac Anesthesia Made Ridiculously Simple by Dr. Art Wallace (UCSF). It’s a concise, high-yield guide that offers a no-frills introduction to the specialty and remains relevant to this day. You can find it at www.cardiacengineering.com/cardiaca.htm [13].

It’s natural to feel hesitant on day 1, but your role genuinely matters. Even as the most junior team member, you contribute directly to the workflow and safety of the case. For those not pursuing cardiac anesthesia, this rotation is still an excellent opportunity to build confidence in managing hemodynamic instability. By reviewing the chart thoroughly, understanding the patient’s comorbidities and medications, and reading about the planned surgical approach, you’ll quickly move beyond the basics and add real value to the team.

Your Role on the Team

The night before my first cardiac anesthesia rotation, I read Cardiac Anesthesia Made Ridiculously Simple by Dr. Art Wallace (UCSF)—a concise, high-yield introduction to the field that remains relevant today (www.cardiacengineering.com/cardiaca.htm). It’s normal to feel hesitant on day 1, but your role matters: even as a junior trainee, you contribute directly to the safety and flow of the case. Cardiac anesthesia is an excellent opportunity to build confidence with hemodynamic management, and by reviewing the chart, understanding the patient’s comorbidities, and reading about the surgical approach, you’ll quickly rise above the baseline and add real value.

As the trainee, your job is to stay aware of everything happening in the room. When the fellow and attending are focused on TEE, you become the eyes and ears: monitoring hemodynamics, watching the field, and catching changes in the patient or equipment. This rotation also teaches true systems-based practice, highlighting coordination between anesthesia, surgery, perfusion, nursing, and the ICU. The skills you develop here—understanding inotropes, perfusion indices, and the hemodynamic consequences of your interventions—will serve you in any high-acuity setting long after you leave the cardiac OR.

Phase 1: Pre-bypass

In the pre-bypass phase, the heart is surgically exposed and prepared. This period is often smooth and controlled unless the patient is undergoing a re-operation, where adhesions from prior surgery can result in significant bleeding during re-entry. Be prepared to respond quickly with volume and pressors.

In CABG procedures, the internal mammary artery (IMA) is typically dissected from the chest wall. This is a meticulous and time-consuming process. To assist the surgeon, you may be asked to lower tidal volumes to improve access. In valve surgeries, the dissection tends to be faster and the exposure less technically complex.

During sternal sawing, ensure that ventilation is paused and that the APL (pop-off) valve is set to zero to prevent inadvertent lung inflation and injury.

Phase 2: Cannulation and Cardiopulmonary Bypass

This is one of the most critical phases of the case. The surgeon will cannulate the major vessels, usually the aorta and right atrium, which carries a risk of vascular injury or dissection. To mitigate this, systemic blood pressure should be reduced during cannulation. Maintaining neuromuscular blockade is another important responsibility at this stage.

Before bypass can begin, the patient must be fully heparinized, typically 300–400 U/kg. Heparin may cause mild vasodilation, so be prepared to adjust support. You and the perfusionist are jointly responsible for maintaining anticoagulation by monitoring activated clotting time (ACT).

Once on bypass, the perfusionist takes over circulation, ventilation, and anesthetic delivery. They will administer volatile agents and draw labs through their circuit. In this scenario, you are tracking one vital sign: MAP. Although your anesthesia team may step out, you have to maintain vigilance and be ready to call them back. Drops in MAP may require supplementing vasopressors, surgeons may ask for TEE visualization, and bleeding can occur.

Phase 3: Coming Off Bypass

The transition off bypass is a highly coordinated moment of the case in which you have to restore natural perfusion using a heart that has been cold and hyperkalemic for a long period of time. Once the surgeon announces the start of rewarming, this signals that bypass is nearing completion. Notify your attending at this point so they can begin preparing for separation from bypass. Ensure the patient is once again deeply paralyzed and resume pulse oximetry monitoring.

The heart will be slowly filled and de-aired, sometimes with assistance from Trendelenburg positioning. Residual air is evaluated via TEE.

As pulsatile flow is restored and the patient begins transitioning back to native circulation, you must resume ventilation and reactivate pulse oximetry since blood is now flowing through the lungs again and can no longer be extracorporeally oxygenated. Resuming ventilation during resumption of pulsatile flow is critical to avoid anoxic injury.

The heart may resume function slowly and often develop arrhythmias. These may be managed with inotropes or cardioversion, depending on the situation. Your choice of vasopressors and inotropes will depend on CVP, PA pressures, and TEE findings. Right ventricular function is especially important to monitor closely during this phase.

When the team confirms that the patient is fully off bypass, the surgeon will instruct you to administer protamine, which irreversibly binds heparin. This drug should be kept hidden away during bypass, as accidental administration while still on the pump can cause catastrophic clotting in the bypass circuit.

If the bypass run was long or the patient has preexisting heart failure, separating from bypass may be especially difficult. The right ventricle, in particular, is vulnerable. It is sensitive to ischemia, poorly protected during bypass (sitting anteriorly and less insulated by the ice bath), and weaker than the LV.

As the surgeon begins to achieve hemostasis and close the chest, shift your focus toward postoperative planning: optimize the blood gas, titrate and organize drips for ICU transport, and prepare a transport medication pack. Ensure lines, monitors, and documentation are in order.