Plan to Prevent or Treat Hemodynamic Instability

Hemodynamic instability may occur during the procedure. Therefore, a plan must be developed to determine how instability will be handled if it occurs.

Ischemic Preconditioning

Ischemic preconditioning is one option available to prevent hemodynamic instability:

  • Occlude the artery.
  • Maintain the occlusion for five minutes. Monitor heart rate, EKG, and hemodynamics.
  • Reperfuse the artery for 2Š3 minutes.
"I use ischemic preconditioning for all arteries. The occlusion is maintained for five minutes as the EKG, hemodynamics, and regional wall motion are monitored, followed by three minutes of reperfusion. The artery is then occluded, opened, and the anastomosis is made. Occasionally, intraluminal occluders are used, but most often back-bleeding is easily controlled with a humidified CO2 misting device."12 - James C. Hart, M.D.

Regardless of whether ischemic preconditioning confers any protective response, a trial occlusion can be performed to assess the initial tolerance to ischemia. If any hemodynamic or rhythm disturbance is noted, appropriate adjustments can be made prior to performing the arteriotomy. Other surgeons have not found trial occlusions or ischemic preconditioning necessary.

Although the use of a shunt has not been proven essential for beating heart CABG, shunting is a technique that should be in every surgeon's arsenal. The dry anastomotic site that shunting provides, along with distal perfusion, are important benefits.

Pacing Wires
The threat of heartblock or asystole is a real concern when occluding the proximal RCA. The RCA can be shunted to prevent potential hemodynamic instability. In the event that instability occurs, having pacing wires available will substantially reduce the threat of deterioration associated with bradycardia and hypotension.


New "First Assistant" Role for the Anesthesiologist

The anesthesiologist is integral to the success of beating heart CABG. In contrast to CABG procedures that use CPB, beating heart CABG requires the anesthesiologist to proactively maintain stable hemodynamics and rhythm in an environment that changes rapidly because of regional ischemia and cardiac manipulation. The anesthesiologist's active role during beating heart CABG requires a new level of communication with the surgeon. The surgeon must communicate to the anesthesiologist when the heart is being displaced, when a coronary artery is occluded, and when a shunt has been inserted or removed. Likewise, the anesthesiologist must keep the surgeon informed about the use of inotropes or vasopressors, ST segment or rhythm disturbances, and the patientÕs general condition. In no other cardiac procedure has it been more important for the anesthesiologist to continually observe and treat the hemodynamic and rhythm responses to cardiac manipulation and regional ischemia.

"Anesthesia is the critical part of the operation. When we occlude the vessel to perform the anastomosis is when hemodynamic instability occurs and not the moment when you go off pump. You have to cooperate very closely with the anesthesiologist in that respect."13 - F.W. Mohr, M.D., Surgeon
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