Cardiac Anesthesia VI Offpump, MiniCab, and assorted extras

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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

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• Off-Pump
• CABG
• Procedures

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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

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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

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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

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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

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OPCAB

• No matter how well the Octopus was placed, there
  is still some residual movement and if the
  hearts 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

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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

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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

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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!!

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• Minimally
• Invasive
• Surgery

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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

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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
• Todays current technologys 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

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Minimally Invasive Surgery

• Minimally invasive technology also is used to
  repair congenital defects (ASDs, VSDs)
• 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

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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

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MIDCAB

• Advantages of the MIDCAB are
• Shorter length of stay (often d/ced 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)

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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 CABGs 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 CABGs and using the
  Minimally Invasive procedures for Valve surgery
  in healthy patients with good to moderate LVF

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Anesthetic Management

• Anesthetic management of minimally invasive
  procedures varies depending on the procedure
• For MIDCABs 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

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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

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Anesthetic Management

• INDUCTION This can be achieved with a combo of
  Propofol (Etomidate), Vec (Zem), and Fentanyl _at_
  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)

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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

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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

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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

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• Pacemakers

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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)

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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 hearts 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

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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)

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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)

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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)

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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

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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

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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

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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

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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)

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• Break
• Time!!!

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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

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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

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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

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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

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• TEE
• Transesophageal
• Echocardiography

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TEE

• The first use of TEE was in 1975 and had a very
  limited range and very little ability to change
  the angle of the view
• In modern equipment with provision of multiple
  planes of view, multiple frequency of probes,
  color flow mapping, pulse and continuous wave
  doppler and digital image processing, the quality
  and utility of todays TEEs have expanded its
  use 100 fold

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TEE

• The common indications for TEE are
• Assessment of valvular function both intra and
  postop
• Evaluation of Mitral valve repair and prosthetic
  valve surgery
• Assessment of Global LVF and regional wall motion
  abnormalities (RWMA)
• Assessment of the aorta for arteriosclerosis,
  calcification and dissections

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TEE

• 5) Detection of intracardiac defects, masses, and
  vegetations
• 6) To see optimal deairing after open heart
  surgery
• 7) For quick evaluation of severe hypotension
  intra and postop by ruling out conditions like
  cardiac tamponade, poor LV volume status, RWMA,
  malfunction of prosthetic valves, or aortic
  dissection
• 8) Inadequate or impossible transthoracic
  echocardiography

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TEE

• Although TEE is a fast and relatively
  non-invasive technique, its routine use for
  NON-cardiac surgery is yet to be established
• Many studies have revealed that TEE is more
  sensitive than EKG for EARLY detection of
  ischemia
• Studies showing the routine use, though, of TEE
  in non-cardiac surgeries as a benefit are limited
  in number and equivocal in outcome

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TEE

• With its use in Open Heart surgery, it is usually
  placed once GA is induced
• The tip is covered with Xylocaine 2 Jelly and
  you can pass the probe blind but guide it down
  with your finger like an LMA or use your
  laryngoscope and pass it under direct vision
• Most people pass it blind with a finger as a guide

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TEE

• It should always be fitted with a Bite Block in
  patients with teeth and the bite block needs to
  be placed BEFORE insertion
• The appropriate depth is where you get the best
  picture but it should end up between 25-30cm
  depth from the teeth
• Usually at this depth you will see the classic
  4-chamber view easily

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TEE

• One of the views that you will need to see for a
  complete exam requires insertion to about 40cm
• This is a cross-sectional view of the heart and
  is the classic Doughnut view or Transgastric
  view
• This view is very useful for monitoring LVF,
  studying RWMA, ischemic changes, LV aneurysm and
  preload of the LV

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Common Clinical Applications of TEE

• Left Ventricular function Assessment
• Detection of Myocardial ischemia through RWMAs
• Assessment of the Mitral valve and its repair
• Assessment of Septal closures and repairs of
  Congenital Heart Diseases
• Assessment of Air removal after Open Heart
  Surgery
• Assessment of proper placement and function of
  Prosthetic valves
• Evaluation for hypotension

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Clinical Applications

• 8) Evaluation of the Aorta for Cannulations and
  Dissections
• 9) Detection of Intracardiac masses, thrombus, or
  valve vegetations
• 10) Measurement of the Cardiac Output

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Complications of the TEE

• TEE is very safe and atraumatic if placed
  correctly
• There are some reported cases of Esophageal tears
  or perforations and burns
• To avoid such complications the probe should be
  introduced with gentleness and care and if ANY
  resistance is encountered, the probe should be
  withdrawn and re-lubed and then another attempt
  can be made to place it

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Absolute Contraindications

• Absolute contraindications to TEE placement are
• Presence of an Esophageal Stricture
• Esophageal tumor
• Recent suture lines as in gastric bypass
• Diverticular disease of the esophagus

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Relative Contraindications

• Relative contraindications include
• Hiatal Hernia
• Esophageal varices
• Esophagitis
• Unexplained Upper GI bleeding

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TEE

• http//www.ucsf.edu/teeecho/content_pages/page6.ht
  m

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References

• http//www.ispub.com/ostia/index.php?xmlFilePathj
  ournals/ijpf/vol1n1/opcab.xml
• http//www.cardiacengineering.com/cardiaca.htm
• http//www.cardiacengineering.com/Midcabg.htm
• http//www.cardiacengineering.com/bbac/PCRRT.pdf

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Scenario 1

• 49 yo w/ chest pain and cath proven Three vessel
  disease for a bypass.
• What questions do you want answered?
• How will you proceed?
• What lines and monitors will you use?
• What will be your Anesthetic plan?

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Scenario 2

• 68 yo male w an acute MI and markedly reduced LVF
  with a Left Main Lesion on Cath.
• What info do you want to know?
• How will you proceed?
• What is your anesthetic plan?

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Scenario 3

• 74 yo female with severe AS and a gradient of 70
  across her valve for an Aortic Valve replacement
• What info do you want to know?
• What is your anesthetic plan?
• What lines and monitoring would you place in her?
• How would you do your induction?

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Scenario 4

• 69 yo m with AR for a cysto for removal of an
  obstructing stone
• What info do you want to know?
• What hemodynamic parameters do you need to follow
  and what changes can you allow?
• What is your anesthetic plan?