Cardiac Anesthesia VI Off-pump, Mini-Cab, and assorted extras

1. Cardiac Anesthesia VIOff-pump, Mini-Cab, and assorted extras Vincent Conte, MD Clinical Assistant Professor FIU College of Nursing and Health Sciences Anesthesiology Nursing Program

2. Off-Pump CABG Procedures

3. Off-Pump CABG • “Off-Pump” (OPCAB) or “Beating Heart” bypass was a technique that was developed about 7 years ago as a new, revolutionary technique • Initially, the numbers showed an across the board decrease in EVERY complication at the 1 and 3 years marks • HOWEVER, at the 5 year mark, the mortality rate of Off-Pump CABG was significantly higher that of the ON-PUMP group and re-stenosis rates were almost double as well

5. Off-Pump CABG • So much for “new and revolutionary” • The technique is still used so it is important to have a working knowledge of it and its anesthesia implications • The main thing that is missing is the CPB Machine • The heart is exposed and a special retractor/STABILIZING device called an “Octopus” is placed to isolate and stop the movement of the site to be grafted to

11. OPCAB • This is accomplished by the use of small suction cups that raise and stabilize the area of the heart to be grafted • Unfortunately, no matter how carefully the Octopus is placed, it still places extrinsic pressure on the heart and will compromise CO to some degree • To counteract that, the patient is usually fluid loaded prior to the placement of the retractor

12. OPCAB • At Baptist, it was our protocol to infuse 1.5-2L prior to the placement of the Octopus • Once the Octopus was placed, we used either inotropes or NTG (whichever way we needed to go) to keep the BP at 90-100mm Hg while the Octopus was in place • The lower pressure would decrease the degree of contractility of the heart and decrease the degree of overall movement

13. OPCAB • No matter how well the Octopus was placed, there is still some residual movement and if the heart’s contractility can be kept to a minimum, that extra movement can be minimized • There were even times when we would use inhalational agents to depress the myocardium and use a Neosynephrine or Levophed drip to maintain BP at 90-100

14. OPCAB • These patients would also be extubated a lot sooner than the patients who had been placed on CPB • Muscle Relaxants would be titrated to keep 1-2 twitches during the procedure and at the end, reversal would be given prior to transfer, and by the time we would get to the unit, spontaneous ventilation would usually have begun

15. OPCAB • Also, since early extubation is part of the goal, you would go easier on the narcotics and use Fentanyl in the 2-5mcg/kg range so their effect would be minimal when it was time to resume spont. Ventilation and possible early extubation • Usually some Fentanyl would be titrated in at the end once spont. vent. resumed prior to extub using resp. rate as the end point of titration

16. OPCAB • When it first came into favor it was all the rage!!! • Everyone was using it as a selling point and there were PR wars between the hospitals that we did it and THEY did not, etc. • Once the 5 year data came out, it almost stopped overnight!!! BUT NO ADDS THIS TIME!!

17. Minimally Invasive Surgery

18. Minimally Invasive Cardiac Surgery • Standard heart surgery typically requires exposure of the heart and its vessels through a median sternotomy • A Minimally Invasive approach allows access to the heart through SMALL incisions and without instituting CPB in some cases • Minimally Invasive surgery is applicable to the broadest range of complex cardiac cases

22. Minimally Invasive Surgery • Minimally invasive procedures, in properly trained hands, can be used safely to perform up to 2-vessel bypass procedures and to repair or replace diseased heart valves • Today’s current technology’s high degree of flexibility and precision have allowed surgeons to successfully perform difficult cases involving both multi-vessel bypass, mitral valve repair, multi valve operations, and aortic valve replacement

23. Minimally Invasive Surgery • Minimally invasive technology also is used to repair congenital defects (ASD’s, VSD’s) • Additionally, the minimally invasive approach is applicable for aortic valve replacement, especially in elderly patients, and is well suited for patients who have had prior valve procedures

25. MIDCAB • Minimally Invasive Direct Coronary Artery Bypass is a minimally invasive approach to conventional CABG • MIDCAB is beating heart surgery and unlike conventional sternotomy, only requires a 3”-5” incision placed between the ribs • MIDCAB results in a faster recovery, fewer complications, and less pain after surgery

27. MIDCAB • Advantages of the MIDCAB are: • Shorter length of stay (often d/c’ed in 2-3 days postop) • Faster Recovery (reduced risk of complications; can return to normal activity within 2 weeks) • Less Bleeding and Blood trauma (the damage to the blood from the CPB machine is avoided; smaller incision-less blood loss) • Lower Infection rate • Available to more patients (poor candidates for conventional CPB may be candidates for less invasive techniques) • Less Cost (25% less than conventional CABG surgery)

28. MIDCAB • The drawback to the MIDCAB procedure is that it requires a Surgeon with a high amount of expertise in the procedure and is only recommended to be used in CABG’s involving two vessels or less • There is also limited data about long-term re-stenosis rates or mortality like with the Off-pump cases • What most surgeons are doing, is going back to conventional sternotomy and CPB especially for multivessel disease for CABG’s and using the Minimally Invasive procedures for Valve surgery in healthy patients with good to moderate LVF

29. Anesthetic Management • Anesthetic management of minimally invasive procedures varies depending on the procedure • For MIDCAB’s a double lumen tube is placed and the left lung is dropped to provide exposure for the procedure • In minimally invasive valve surgery, a regular ETT can be placed and CPB is instituted via a Fem/Fem connection and the heart is put at rest through the use of CPB

30. Anesthetic Management • Like with the Off-pump, the MIDCAB usually requires volume loading to compensate for the pressure placed on the heart by extrinsic retractors • The L Lung is usually dropped to aid in the procedure and give better exposure to the surgeon

31. Anesthetic Management • INDUCTION: This can be achieved with a combo of Propofol (Etomidate), Vec (Zem), and Fentanyl @ 7.5-10mcg/kg • MAINTENANCE: Continuous Propofol infusions can be used, as well as Inhalational agents, O2 and N2O (no CPB), Fentanyl, and Vec (Zem) • EMERGENCE: Reversal can be done with normal agents (Neostig and Robinul)

32. AHA Statement • The American Heart Association has been carefully monitoring minimally invasive procedures and their outcomes • While all the surgeries appear promising, the conclusion of the AHA is that they need much more study before they are recommended over conventional methods

33. AHA Statement • Information is being gathered and scrutinized at many medical centers across the country • If these surgeries can be refined to the point where they are no more invasive than angioplasty, they will end up having a distinct advantage over angioplasty • However at this point they are more invasive than angioplasty and require GA instead of MAC

34. AHA Statement • Based on the preceding, at this point in time, minimally invasive surgeries are considered experimental and are NOT recommended over more conventional, time tested techniques • This may change as more data is collected, but at this time no recommendation can be made for or against them

35. Pacemakers

36. Pacemakers • Definitions of common terms: • Pacemaker: The mechanical system which achieves pacing • Electrode: Part of the pacemaker that is in contact with the myocardium • Bipolar: An electrode system in which BOTH electrodes are in touch with the myocardium • Unipolar: An electrode system in which one electrode is in the heart and the other is NOT in the heart (usually the pacer itself is the OTHER lead)

37. Pacemakers • General types of pacing: • ASYNCHRONOUS: This type of Pacer has NO sensing capability to detect R waves. This form of pacing is in competition with the heart’s own beat and has been known to cause V-fib at times (R on T) • SYNCHRONOUS: This Pacer has the appropriate circuit to detect intrinsic R waves

38. Pacemakers 3) SEQUENTIAL: Also called A-V sequential, it paces the atrium first then paces the ventricle after a set time period (A-V interval; usually set in milliseconds)

39. Pacemakers • Three-letter system: • First Letter: Indicates the chamber that is paced (A,V,D) • Second Letter: Indicates the chamber that is sensed (A,V,D,O) • Third letter: Indicates the mode of action (O, I, T, B, D)

40. Pacemakers • Definition of letters: • O = Asynchronous or no programming • A = Atrium • V = Ventricle • D = Dual (both Atria and Ventricle) • I = Inhibited • T = Triggered • B = Burst (rarely seen)

41. Pacemakers • Examples: VOO (AOO): A simple Ventricular or Atrial Asynchronous non-sensing pacemaker VVI: Paces the ventricle; senses the ventricle and is inhibited by a rate set above its rate DVI: Paces both Atria and Ventricle; the ventricle is sensed and it is inhibited if the rate is higher than its set rate DDI: Both are Paced; Both are sensed and it is inhibited

42. Anesthetic Management • The first step in Anesthetic management is to know WHY they have the Pacemaker (Complete heart block, Sick Sinus Syndrome, Bradycardia, etc.) • If they have a condition that requires a Pacer, then keep the pacer as is and keep a magnet at hand to use if necessary • Bovey activity may interfere with the pacer so if that happens, you may need to place the magnet on the pacer to put it into the VOO mode

43. Anesthetic Management • If they have a condition that they DO NOT need the pacer to live, then the pacer is usually placed in an asynchronous mode • Still keep the magnet handy in case there is interference and you need to put it into its VOO mode • If the patient has an AICD, this needs to be DEACTIVATED prior to surgery AT ALL TIMES

44. Anesthetic Management • One should apply the following measures to decrease the possibility of adverse effects due to electrocautery: • Bipolar cautery should be used if available • If unipolar cautery is used, place the grounding pad as far away from the pacer as possible • Electrocautery should NOT be used within 15cm of the Pacer

45. Anesthetic Management 4) Pacemakers should be programmed to asynchronous in the preop suite by the pacer tech or be done with a magnet in the OR if needed 5) Provisions for alternative temp. pacing should be readily available (pads for transcutaneous, crash cart in room)

46. Break Time!!!

47. Valve Replacement Surgery • The only additional step for Valve replacement surgery that changes it from CABG management techniques is the DE-AIRING step after the valve has been repaired/replaced • The patient is placed in a head down position and using the TEE usually as a guide, the heart is allowed to fill up by the pump tech just partly clamping the venous return line and the cross clamp being slowly released

48. Valve Surgery • The surgeon will usually massage the heart and shake it a little to dislodge any air that may be trapped on the walls or in the muscle • You can see the air on the TEE as a shower of little white specks and they will gradually decrease as they are circulated and withdrawn by the pump and filtered out

49. Valve Replacement • The surgeon will also usually put another vent or drain and put it to suction below the cross clamp to suck out as much of the air as possible prior to release of the aortic cross clamp • This is just another step to prevent any air embolizing to the brain

50. Valve Replacement • I have found through personal experience that Inotropes are needed about 50% more often with valve surgeries than in CABG surgery • I think since the heart is actually being opened and the tissue is being cut and sewn, that there is a much higher degree of direct myocardial damage so even with short pump runs, the heart needs more help to get really going again after bypass