Mod3: MINIMALLY INVASIVE CARDIAC PROCEDURES Flashcards
MINIMALLY INVASIVE CARDIAC PROCEDURES
Minimally invasive cardiac procedures are becoming more and more of a mainstay. They are replacing the traditional sternotomy for which pt population?
Pts that are not candidate for open sternotomy
While minimally invasive cardiac procedures haven’t been fully adopted for use in all pt’s populations, they are becoming more and more favorable
OFF PUMP CABG
Coronary Artery Bypass Grafting (CABG) has traditional been performed with the use of which machine?
The Cardio Pulmonary Bypass (CPB) machine
OFF PUMP CABG
Studies have suggested that the heart function is better preserved if it is managed which way during the operation?
If it is not stopped during the operation
OFF PUMP CABG
Which approach to cardiac surgery is also known as the “beating heart” surgery or OBCAB
OFF PUMP CABG
Technique developed as new revolutionary procedure performed without the use of a cardiopulmonary bypass machine
OFF PUMP CABG
Advantages:
Reduction in risk of stroke,
<em>Although the rate of neuro cognitive dysfunction remains the same</em>
Less systemic anticoagulation needed
Thought to avoid potential morbidities associated with extracorporeal membrane
Faster recovery and reduced procedural costs
Eliminate risk of aortic manipulation for cannulation and cross-clamping
OFF PUMP CABG
Potential morbidities associated with extracorporeal membrane that may be avoided by performing “Off Pump CABG” inlude?
Systemic inflammatory response
Platelet activation
Fibrinolysis
Bleeding
Vasodilatory shock
OFF-PUMP CABG MORBIDITY AND MORTALITY
What are disadvantages of “Off-pump CABG”?
More challenging, requiring additional training
Difficulty performing distal anastomoses on the distal part of the beating heart
Motion of coronary artery hampers accurate anastomotic suturing
<em>The beating heart causes the coronaries to move, which can impede accurate anastomotic suturing</em>
Heart must be manipulated and lifted to reach posterior and lateral targets
<em>And this can cause a significant left to right ventricular hemodynamic deterioration</em>
OFF-PUMP CABG MORBIDITY AND MORTALITY
How does “Off-pump CABG” affect morbidity and mortality at 1 and 3 year marks
At 1 and 3 year marks, OPCAB showed a reduction in morbidity and mortality
Initially, studies that evaluated mortality showed a reduction in death a/w off pump CABGs
OFF-PUMP CABG MORBIDITY AND MORTALITY
Why are higher long term mortality rates (at the At 5 year mark) seen with “Off-pump CABG”?
Reduction in graft patency (Worse graft patency)
Increased risk for repeat revascularization (Less complete revascularization)
OFF-PUMP CABG MORBIDITY AND MORTALITY
What does “Repeat revascularization” means?
….
OPCAB PATIENT SELECTION
What’s the goal for “Off-pump CABG”?
Complete revascularization
Pts are selected with this goal in mind
OPCAB PATIENT SELECTION
T/F: OPCAB has been choosen for low-risk as well as high-risk pts
True
OPCAB PATIENT SELECTION
What’s an example of a low risk pt for whom OP-CABG can be choosen?
Pt with a single of fewer number of diseased vessels
OPCAB PATIENT SELECTION
What’s are examples of a high-risk pt for whom OP-CABG can be choosen?
Patients with contraindications to conventional CABG
Pts who have plaque in the ascending aorta
Pts with extensive aortic atheromatous or calcific changes
Pts who have comorbidities such as stroke, liver cirrhosis and renal or pulmonary dysfunction
History of stroke
OPCAB PATIENT SELECTION
Why is OP-CABG indicated for pts who have plaque in the ascending aorta, or pts who show extensive aortic atheromatous or calcific changes?
Because conventional CABG precludes them from aortic cross-clamping
OPCAB PATIENT SELECTION
Besides low and high risk groups, for which other categories of pts is OP-CABG indicated?
Patients with isolated proximal LAD CAD/fewer number of diseased vessels
Occasionally patients with LAD and proximal RCA CAD
Pts with No prior cardiac surgery history
OPCAB PATIENT SELECTION
Other considerations for OP-CABG include?
Surgeon expertise
Extent of atherosclerosis of ascending aorta
Extent of technically challenging anatomy
MINIMALLY INVASIVE DIRECT CORONARY ARTERY BYPASS
What’s the most popular alternative to sternotomy that utilizes a limited thoracotomy incision?
Minimally invasive Direct Coronary Artery Bypass
Also known as a MIDCAB
MIDCAB is a minimally invasive approach to conventional CABG
MINIMALLY INVASIVE DIRECT CORONARY ARTERY BYPASS
MIDCAB can be performed two ways
Can be performed with
Elimination of CBP and cardioplegia, or
Elimination of cardioplegia only
For the purpose of this lecture, we will focus on the option that involves Elimination of CBP and cardioplegia
So the MICAB will be very similar to “off-pump CABG”
MINIMALLY INVASIVE DIRECT CORONARY ARTERY BYPASS
Why is the A left anterior thoracotomy is used for the MIDCAB procedure?
It allows for direct access to the IMA for harvesting and grafting to the LAD
MINIMALLY INVASIVE DIRECT CORONARY ARTERY BYPASS
The MIDCABs can be categorized into three groups; that are?
Direct access MIDCAB
Thoracoscopic MIDCAB
Robotic MIDCAB
MINIMALLY INVASIVE DIRECT CORONARY ARTERY BYPASS
Why are Thoracoscopic MIDCABs and Robotic MIDCAB also known as endoscopic MIDCABs?
Because they use a video-assisted device
Many facilities that perform MIDCABs use the Thoracoscopic or Robotic approaches
MINIMALLY INVASIVE DIRECT CORONARY ARTERY BYPASS
The standard approach MIDCAB that uses an anterior thoracotomy is also known as
Direct access MIDCAB
MINIMALLY INVASIVE DIRECT CORONARY ARTERY BYPASS
Why are many Centers shying away from Direct access MIDCAB?
Visualization of the LIMA is difficult and
The rib-spreading required for visualization is associated with postoperative thoracotomy pain
<em>Many facilities that perform MIDCABs use the Thoracoscopic or Robotic approaches</em>
MINIMALLY INVASIVE DIRECT CORONARY ARTERY BYPASS
Which MIDCAB approach uses small thoracoscopic ports for incision sites
Thoracoscopic MIDCAB
It uses the Non-rib-spreading technique
MINIMALLY INVASIVE DIRECT CORONARY ARTERY BYPASS
What are benefits of the Non-rib-spreading technique used in Thoracoscopic MIDCABs?
Non-rib-spreading technique is associated with
Very good flow down the LIMA, and
High LIMA-LAD graft patency
MINIMALLY INVASIVE DIRECT CORONARY ARTERY BYPASS
Which MIDCAB approach uses thoracoscopic ports, but also utilizes a robot to harvest the LIMA
Robotic MIDCAB
MINIMALLY INVASIVE DIRECT CORONARY ARTERY BYPASS
What are benefits of Robotic MIDCAB
Excellent visualization and maneuverability of instruments inside the thoracic cavity
Good quality of harvested LIMA
Good LIMA to LAD anastamosis
MINIMALLY INVASIVE DIRECT CORONARY ARTERY BYPASS
Which MICAB approach requires deflation of the lung on the operative side?
Robotic MIDCAB
MIDCAB ADVANTAGES
What are advantges of MIDCAB’s small thoracic incisions, especially the non-rib-spreading ones
Eliminate the potential morbidity a/w CABG and the median sternotomy
Results in potential for more rapid and complete recovery
MIDCAB ADVANTAGES
For which cardiovascular procedures do utilizing MIDCABs offers advantages?
Repair congenital defects like ASDs and VSDs
Aortic valve replacements
MV repairs
Multivalves procedures
MIDCAB ADVANTAGES
Overall, what are advantages of MIDCAB procedures?
Lower Infection rate
Less Cost (25% less than conventional CABG surgery)
Shorter length of stay
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)
Available to more patients (poor candidates for conventional CPB may be candidates for less invasive techniques)
Applicable to a broad range of complex cardiac procedures
PLACEMENT OF INCISION DURING MINIMALLY INVASIVE HEART VALVE SURGERY
Where is the incision placed for minimally invasive aortic valve surgery?
Below the right clavicle, and
Above the right nipple
PLACEMENT OF INCISION DURING MINIMALLY INVASIVE HEART VALVE SURGERY
Where is the incision placed for minimally invasive mitral and intracupsid valve surgery?
Below the right nipple
MIDCAB DISADVANTAGES
What percent reduction in mortality rates was oberved when MIDCABs were performed by more experienced surgeons?
5% reduction in mortality rates
A meta-analysis documented a significant surgeon volume relationship with a 5% reduction in mortality rates in surgeons who perform high volumes of these procedures
MIDCABs Require experienced surgeon for best outcomes
MIDCAB DISADVANTAGES
What’s a disadvantage of the small MIDCAB incisions?
Limited access to specific regions of the heart
Poor access to distal RCA and PDA
Make complete re vascularization difficult, especially when it comes to identifying and bypassing smaller myocardial vessels
MIDCAB DISADVANTAGES
Why is constructing inflows to secondary grafts with MIDCABs procedures?
Proximal anastomosis to the ascending aorta more challenging
MIDCAB DISADVANTAGES
What would will make Robotic surgery procedures technically difficult?
Any anatomical issues that hinder port placement or limit robotic arm movement
Prior thoracic surgery
Chest radiation
Thoracic trauma
MIDCAB DISADVANTAGES
T/F: Higher blood transfusion rates associated with robotic cardiac surgery than with other robotic procedures
True
MIDCAB PATIENT SELECTION
Why is appropriate patient selection is important?
To reduce the risk of perioperative complications
MIDCAB PATIENT SELECTION
Robotic or Thoracoscopic (Endoscopic) approaches may not suitable for smaller pts; why?
Insufficient intrathoracic space for CO2 insufflation
MIDCAB PATIENT SELECTION
T/F: Except for difficulty with smaller pts and endoscopic procedures, the pt selection for MIDCAB is Similar to the patient selection for Off pump CABG
True
MIDCAB PATIENT SELECTION
Except for difficulty with smaller pts and endoscopic procedures, the pt selection for MIDCAB is Similar to the patient selection for Off pump CABG and include?
Patients who are considered low risk with anterior lesions specifically of the LAD
Those with fewer number of diseased vessels
High risk patients or patients with contraindications for bypass surgery
Or if they are scheduled to have a sternotomy for another cardiac procedure
MIDCAB PATIENT SELECTION
High risk patients or patients with contraindications for bypass surgery include
Extensive ascending aorta atheromatous or calcific changes
Patients who require reoperation, but in whom a sternotomy or CPB is contraindicated/higher risk
Future sternotomy for other cardiac procedure
MIDCAB PATIENT SELECTION
Patients who require reoperation, but in whom a sternotomy or CPB is contraindicated/higher risk include:
Patients who require redo-sternotomy, but have cardiac sutures adhering to the posterior sternum
Previous sternal infection
Mediastinal radiation
OPCAB and MIDCAB SURGICAL CONSIDERATIONS
Describe vessel harvesting, incision and anastamosis with the MIDCAB procedure (Anterior thoracotomy approach)
an anterior thoracotomy is made and
the internal mammary artery (Left or Right) is harvested from the thoracic wall
For anastamosis to the LAD
OPCAB and MIDCAB SURGICAL CONSIDERATIONS
Describe vessel harvesting, incision and anastamosis with the OPCAB procedure
The conduit vessels, either the saphenous vein, or radial arteries, are harvested in the same fashion that they would be for a traditional CABG
A sternal incision is then made
The pericardium is opened and tacked to the edges of the mediastinum
<em>This raises the heart out of the chest wall</em>
Sternal retractors placed
<em>Allow for the placement of surface pressure devices on the myocardium called stabilizers</em>
OPCAB and MIDCAB SURGICAL CONSIDERATIONS
What results when the pericardium is opened and tacked to the edges of the mediastinum?
This raises the heart out of the chest wall
OPCAB and MIDCAB SURGICAL CONSIDERATIONS
For OP-CAB what’s another name for the surface pressure devices on that are placed on the myocardium after Sternal retractors are placed?
Stabilizers
OPCAB and MIDCAB SURGICAL CONSIDERATIONS
Where are Stabilizers placed? What’s their function?
Placed on epicardium over planned site of arteriotomy
Stabilize the myocardium to reduce movement of the site of anastamosis
Example of stabilizer: Octopus Stabilizer
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
For both OPCAB and MIDCAB, why must the cardiopulmonary bypass machine is on standby?
In the event that emergency bypass is needed
A perfusionist must be in attendance
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
T/F: Double lumen tube, bronchial blocker, or endobronchial tube will be inserted for MIDCAB procedures
True
Why?…
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
Why should External defibrillator pads should be placed for both procedures; especially for MIDCAB procedures?
Because the surgeon will not have direct access to the heart to place internal pads in the event of V-fib
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
What monitors must be available for both OP-CAB and MIDCAB procedures?
All the traditional monitors for traditional cardiac surgery:
5-lead EKG - Pulse oximetry
Temperature monitoring - Radial arterial line
Central venous catheter/ PAC ?
Foley Catheter - TEE
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
What are the anesthetic goal for off pump cases?
Ensure that there is maximum cardiac protection
Stable hemodynamics and cardiac rhythm
Promote fast-track anesthesia
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
What does fast-track anesthesia means? What’s required to achieve it?
Extubation within 0-6 hours after ICU admission
Adequate postoperative analgesia is required to achieve fast-track anesthesia
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
How can anesthesia be delivered for OPCAB and MIDCAB?
General anesthesia (GA) with opioids and inhalational agents or TIVA
Combined GA with controlled ventilation and neuroaxial blockade using high thoracic epidural
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
General anesthesia with the use of opioids and inhalational agents offer the advantage of
Anesthetic ischemic preconditioning
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
Why must careful consideration be taken with the use of neuromuscular blocking agents during General anesthesia
May interfere with the goal is fast-tracking
Roc and Nimbex are recommended
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
Remifentanil a good option for General anesthesia (GA) with opioids and inhalational agents or TIVA, but
must ensure adequate analgesia prior to discontinuation
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
What are the benefits of combined GA with controlled ventilation and neuroaxial blockade using high thoracic epidurals?
Improved analgesia, pulmonary outcomes, and reduction in M&M
They ensure hemodynamic stability and decrease myocardial O2 demands by attenuating the neuro hormonal response
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
When must thoracic epidural be inserted to reduce the risk of developing epidural hematomas?
The day before surgery or
1 hour prior to Heparin administration (minimally)
Important to assess patient’s preoperative anticoagulation status
OP-CAB HEMODYNAMIC CONSIDERATIONS
Hemodynamic instability during off pump cabgs due to
Myocardial ischemia
Mobilization and stabilization of heart for OPCAB
Pushing and tilting the heart for exposure of anastomosis sites
OP-CAB HEMODYNAMIC CONSIDERATIONS
Mobilization and stabilization of heart for OPCAB necessitates pushing and tilting the heart for exposure of anastomosis sites. What are the negative consequences of this?
Reduces stroke volume and ABP
Increases CVP and RVEDP
which leads to decreased RVOT flow
Distortion of mitral and tricuspid annuli
which can either cause or worsen regurgitation through those valves
OP-CAB HEMODYNAMIC CONSIDERATIONS
Mobilization and stabilization of heart for OPCAB necessitates pushing and tilting the heart for exposure of anastomosis sites. What’s the treatment for the negative effects associated with this?
Inotropes and vasopressors
Adequate, but cautious fluid management
Fluid loading prior to stabilizing device being placed
Trendelenburg
OP-CAB HEMODYNAMIC CONSIDERATIONS
Mobilization and stabilization of heart for OPCAB necessitates pushing and tilting the heart for exposure of anastomosis sites. This is could have negative effects including hypotension. What should you do If hypotension persists despite the treatment?
Myocardial ischemia should be suspected and evaluated by monitoring the EKG and the TEE
Consider conversion to cardiopulmonary bypass if hypotension unresponsive
OP-CAB HEMODYNAMIC CONSIDERATIONS
Mobilization and stabilization of heart for OPCAB necessitates pushing and tilting the heart for exposure of anastomosis sites. This could have negative effects that are typically not seen with MIDCAB. Why not?
Not much cardiac manipulation
MIDCAB HEMODYNAMIC CONSIDERATIONS
Hemodynamic instability less likely - why?
Reserved for single vessel disease of the LAD
Procedure done on anterior side of the heart
Not much heart manipulation
MIDCAB HEMODYNAMIC CONSIDERATIONS
Why is there a potential for ventilation/perfusion issues in endoscopic MIDCAB procedures that utilize a robot?
One lung ventilation required with double lumen ETT or bronchial blocker
May result in oxygen desaturations
MIDCAB HEMODYNAMIC CONSIDERATIONS
Why do endoscopic MIDCAB procedures that utilize a robot result in oxygen desaturations from One-lung ventilation?
The non ventilated lung continues to be perfused despite it not taking part in gas exchange
Subsequently, these pts develop a “right to left intrapulmonary shunt”
Deoxygenated blood from non-inflated lung mixing with oxygenated blood from ventilated lung
Hypoxic Pulmonary Vasoconstriction (HPV) attempts to correct by reducing blood flow to non-ventilated lung
However we do know that HPV can be attenuated by anesthetic gasses a vasopressors
There is also a risk for barotrauma!!!
MIDCAB HEMODYNAMIC CONSIDERATIONS
Which gas is used for insufflation of the thoracic cavity (left hemithorax)? Why?
CO2
This allows for exposure of the heart and great vessels as well as preventing smoke formation during cautery usage
MIDCAB HEMODYNAMIC CONSIDERATIONS
Which CO2 levels are adequate to visualize cardiac structures?
5-10 mmHg
MIDCAB HEMODYNAMIC CONSIDERATIONS
What’s a possible negative effect of CO2 levels of 5-10 mmHg
Increased intrathoracic pressure
Decreased venous return
Which can impair systemic BP and worsen hypoxia
MIDCAB HEMODYNAMIC CONSIDERATIONS
Negative effects () of 5-10 mmHg of CO2 used to insufflation thoracic cavity will be more pronounced in patients with
Reduced ventricular function
Increased risk for hypercapnia
MIDCAB HEMODYNAMIC CONSIDERATIONS
Patient positioning; why?
Supine position with roll underneath left scapula
- Facilates surgical exposure*
- Provides adequate room for the robot and the robotic arm to move freely*
MIDCAB HEMODYNAMIC CONSIDERATIONS
Why is it important to note the position of the left arm?
The left arm must be positionned posteriorly at the pt side for adequate exposure
However, caution must also be used to watch for brachial plexus injuries
This becomes especially important in longer procedures where the pt is in this position for a long period of time
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
Which technique is used by many surgeons to create the anastomosis in a blood-less field?
Temporary occlusion of the target coronary artery
Surgeons will temporarily occlude the target coronary artery to create a blood-less field for anastomosis of the grafts
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
Heparin should be administered prior to the occlusion of the target coronary artery. At which dose and for ACT target?
150-200 units/kg, target ACT >300 s
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
During Temporary occlusion of the target coronary artery, maintain HR and MAP of:
HR 70-80 bpm, MAP >70 mmHg
This is to allow for adequate coronary perfusion
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
The patient’s response to occlusion depends on
Degree of collateral circulation
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
Why is Temporary occlusion of the target coronary artery tolerated poorly in Moderate stenosis?
Poor collateral circulation
The stenotic lesion has not been present for long enough to develop adequate collateral circulation
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
Why is Temporary occlusion of the target coronary artery tolerated better in severe stenosis?
More well developed collateral circulation
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
Prior to occlusion, the surgeon may temporarily occlude the coronary artery and then re-perfuses it prior to making the anastomosis. What is this technique called?
Ischemic preconditioning
The surgeon may do this a couple of times to preconditionne the heart to be able to tolerate longer period of ischemia that would be required to make the final anatamosis
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
What’s the purpose of Ischemic preconditioning?
To enhance myocardial performance to decrease ischemic damage during a subsequent prolonged period of ischemia
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
Which drugs can also be increased for preconditioning?
Inhalational agents
Use of inhalational agents => anesthetic preconditioning
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
When do ischemic changes that occur on the EKG tend to disappear?
After reperfusion
Ischemic changes disappear after coronary re-perfused
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
The ischemic changes that occur on the EKG tend to disappear after reperfusion. So why would the EKG sometimes show T-wave inversion, or the TEE may show regional wall abnormality?
This is Secondary to myocardial stunning and reperfusion injury
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
Which Eeectrolytes should be closely monitored postop? why?
Potassium or Magnesium
To prevent reperfusion arrythmias
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
How should arrythmias be treated?
Arrythmias should be treated promptly
Use of a pacemaker should be employed if necessary
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
Neuromuscular blockade reversal will depend on
Stability of the patient and
How soon extubation is anticipated
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
What’s required for extubation to take place?
Hemodynamic stability and
Warm normovolemic patient who is alert and pain free
OPCAB and MIDCAB ANESTHETIC CONSIDERATIONS
What’s the special consideration for using Protamine for heparin reversal?
Consider on a patient by patient basis
Full versus partial reversal
