Anesthesia for Cardiothoracic Procedures Flashcards
Surgical approaches in cardiac surgery
- Open heart surgery (sternotomy or thoracotomy)
- Davinci robotic
- Endovascular (valve repair/aortic repair)
Invasive technique
Open sternotomy technique
Cardiac surgery technique with most possible complications
Invasive
Best exposure for cardiac surgery techniques
Invasive
Minimally invasive techniques
- Thoracotomy approach
- Davinci Robotic approach
- Endovascular
Less common cardiac surgery techniques
Minimally invasive
Implications of minimally invasive surgeries
- One lung may need deflated, so a double lumen tube is needed
- Can be performed off pump, or use bypass through femoral vessels
Common aortic repair surgery
Endovascular
Surgical options for CABG
- Full bypass with arrested or beating heart
- Partial bypass with a beating heart
- Off pump
- Sternotomy
- Thoracotomy
- Davinci
How is a MICS CABG done?
- Small thoracotomy incision
2. Most commonly performed off pump
What is MICS CABG reserved for?
1 or 2 vessel disease since exposure is limited to the anterior vessels
What is the Davinci used for in CABG?
To harvest LIMA
How is the graft sewn in Davinci CABG?
Through a small, anterior thoracotomy incision
What is hybrid coronary revascularization?
Anterior vessels are bypassed with MICS/thoracotomy approach by cardio and more difficult to expose vessels are stented by IR without sternotomy
What are hybrid rooms used for?
- Hybrid coronary revasularization
2. Transcatheter aortic valve replacement (TAVR)/Transcatheter aortic valve implantation (TAVI)
What was shown to be superior to intravascular stent placement?
LIMA to LAD graft without sternotomy
Premedication for CABG
Avoid anxiety and tachycardia for CAD, heavier medication than valve replacement
Surgical options for valve repair/replacement
- Full bypass with an arrested or beating heart
- Right Heart bypass
- Endovascular or transapical valve replacement (both off pump)
- Sternotomy
- Thoracotomy
- Davinci
How are stenotic heart valves fixed?
- Most commonly replaced for better outcomes
2. Can remove calcifications
How are regurgitant valves fixed?
Repaired or replaced
Premedication for valve repair/replacement
Causes hypotension and vasodilation, which reduces preload and afterload. Need to maintain preload and afterload, so try to avoid premedication
Is valve repair/replacement with MICS commonly performed on or off pump?
On pump with bypass cannulation in the femoral vessels
When is endovascular valve repair an option?
For patients who may not qualify for open heart surgery
When are patients considered at too high of a risk for heart surgery?
30-40% of patients with aortic stenosis
Other names for endovascular aortic valve replacement
TAVR or TAVI
Possible catheter/stent pathways for TAVR/TAVI
- Femoral artery to aortic valve (most common)
2. Axillary artery to aortic valve
Catheter/stent pathway for mitral valve repair
Femoral vein to intra-atrial septum to mitral valve
Catheter/stent pathway for tricuspid and pulmonary valves
Femoral vein and passing through R side of the heart
Valve replacement being performed “off pump” with an “open” approach
Transapical valve replacement
Risks associated with endovascular TAVR
- Stroke & TIA
- Perivalvular leak
- Vascular complications (perforation, dissection and/or rupture)
- AKI (due to contrast used)
- Cardiac conduction abnormalities (LBBB)
- Postop bleeding and afib
Does TAVR or surgical replacement have a higher risk of stroke?
TAVR
Which valve has a higher risk of a leak after repair/replacement?
Aortic regurg
Most frequent adverse outcome associated with TAVR
Vascular complications
How can vascular complications be limited with TAVR?
By using transapical thoracotomy
Anesthetic management for endovascular TAVR (10)
- Renal protection
- Stroke prevention
- Lower dose of heparin
- Placement of transvenous pacing leads
- Attaching of external defibrillator pads
- TEE
- No Amicar
- Keep heart still
- Hemodynamic goals
- Continuous post op EKG for 48 hrs
Renal protection for endovascular TAVR
- Adequate perioperative volume loading
2. Administration of N-acetylcysteine prior to surgery
Stroke prevention for TAVR
Dual antiplatelet therapy started before the procedure and continued for 6 months (loading dose of 300mg-325mg ASA and 300 mg Plavix prior to procedure)
Goal ACT for endovascular TAVR
> 250s
How do you keep the heart still during valve deployment for TAVR?
- RVP (rapid ventricular pacing) with rate of 180-220 bpm
2. Virtually stopping heart with adenosine
Should you be concerned with hypotension when keeping the heart still during TAVR?
No, valve deployment is quick and rebound hypertension can exacerbate valvular regurge
Hemodynamic goals for patients with aortic stenosis
- Preload augmentation (inc)
- Low HR (50-70 bpm)
- Maintain sinus rhythm
When is a temporary pacemaker left after TAVR?
In all patients with AV block
Management for endovascular aorta surgery
- No sternotomy/bypass
- Less heparin
- No Amicar
Techniques for aortic root replacement
Traditional bypass with arrested heart bc clamp can be placed on ascending aorta
Surgical techniques for open ascending aorta repair
- Traditional bypass w/o circ arrest if clamp can be placed on ascending aorta
- DHCA or normothermic antegrade cerebral perfusion if aneurysm extends into aortic arch
Problem with open descending aorta repair
Not possible to perfuse both head and lower extremities with one arterial cannula
Open ascending aorta repair options
- Partial cardiopulmonary bypass
- Left heart partial bypass
- Circ arrest
Increases the chance of paralysis from inadequate spinal cord perfusion
Clamps on descending aorta
Oxygenator must be used with this technique
Descending aorta repair with partial CPB
Anesthetic considerations for left heart bypass
- Requires intensive vigilance to hemodynamics by both the anesthesiologist and the perfusionist
- Arterial pressure should be measured in the R radial artery and femoral artery to assess pressure distal to the clamp
- CVP should be compared to PA diastolic or wedge pressure to assess filling of the two ventricles
What happens if pressure is too high proximally and low low distally in L heart bypass?
Flow is increased through the circuit
What happens if both pressures are too low in L heart bypass?
Fluids or vasoconstrictors should be considered
What happens if both pressures are too high in L heart bypass?
A vasodilator should be considered
Anesthetic management for open descending aorta repair
- Place A-line in R arm
- Insert double lumen tube
- Prepare standard cardiac drugs
- Consider techniques for spinal cord protection
Why is the A-line placed in the R arm for open descending aorta repair?
Clamping proximal to L subclavian artery may be necessary
Why insert a double lumen tube for open descending aorta repair?
A thoracotomy approach will most likely be used
Possible spinal cord protection techniques for open descending aorta repair
- SSEP/MEP monitoring
- Lumbar drain (inc spinal cord perfusion pressure)
- Steroids (dec swelling)
- Mannitol (inc spinal cord perfusion through dec CSF production and improves renal perfusion)
Spinal cord perfusion pressure equation
Spinal cord PP = MAP-CSF pressure
Open chest procedure to treat aortic aneurysm
Aortic wrapping procedure
Heart transplant classifications
- Orthotopic
2. Heterotopic
What is an orthotopic heart transplant?
- Replacing the recipient heart with the donor heart
2. Biatrial, bicaval, total heart transplant
What is a heterotopic heart transplant?
The donor heart is placed in the R chest alongside the recipient organ and anastomosed to allow blood to pass through either or both hearts
What is biatrial heart transplant?
- Only the ventricles are removed
2. Donor heart attaches to original at the midatrial level
How many anastomosis’ does a biatrial transplant require?
4
- Aorta
- Pulmonary artery
- Left atrium
- R atrium
What is a bicaval heart transplant?
- The entire R atrium is removed
2. Anastomosis’ at SVC and IVC instead of atrial level
Number of anastomosis with bicaval heart transplant
5
- Aorta
- Pulmonary artery
- L atrium
- SVC
- IVC
What is a total heart transplant?
Removal of all heart, including L atrium
How many anastomosis does the total heart transplant require?
6
- Aorta
- Pulmonary artery
- Pulmonary veins x2
- SVC
- IVC
Advantages of the biatrial technique
- Shorter operation times
2. Less anastomotic complications
Risk of biatrial technique
- Post op atrial arrhythmias
- Atrial enlargement
- Atrial thrombi
- Tricuspid valve regurge
The more heart you remove, the (better/worse) post op function, but the operation times will be (shorter/longer)
Better post op function, longer operation times
Releases Ach to bind to muscarinic receptors on the SA node
Presynaptic vagus nerve
Can atropine and robinul increase HR in patients that have had a heart transplant?
Only after Neostigmine is given due to the increased release of Ach
What patients have a stronger right ventricle?
Patients with pulmonary hypertension
Patients with heart failure are more likely to develop:
pulmonary hypertension and R ventricular hypertrophy
What is the problem with pulmonary hypertension and heart transplants?
The pt still has high pulmonary vascular resistance, but now has a normal sized R ventricle that cannot pump against the high PVR, causing post-transplant R heart failure
What is a transplant option for patients with severe pulmonary hypertension or CHF?
Heterotopic heart transplant
- old heart pumps blood to lungs (R vent)
- new heart pumps blood to body (L vent)
- Over time, pulmonary HTN will resolve
Implications of denervation
- Resting HR is usually faster (>90bpm)
- Atropine and Robinul (alone) have little to no effect on HR
- Neostigmine causes bradycardia, which can be treated with anticholinergics
- Bradycardia must be treated with pacing or with beta 1 agonists
- Pt cannot experience angina
- Baroreceptor reflex doesn’t work, so HR may not respond to changes in BP
- Sympathetic “reinnveration” can occur within 12 mos of operation
- Inc of CO following exertion is primarily due to an increase in SV
- If biatrial technique is used, the SA node of the donor controls HR and 2 P waves will be produced
Anesthetic management for heart transplant procedure
- PA pressure should be kept low to prevent R heart failure
- Inotropic support is more likely to be needed than for other cardiac operations
- Immunosuppressive therapy should be implemented
- Beware of hyperkalemia post transplant
Strategies to reduce pulmonary artery pressure
- Hyperventilation
- Higher FiO2
- Pulm vasodilators (nitrates, prostaglandin, NO)
- Avoidance of acidosis
Where are venous cannulas placed for heart transplants?
In SVC and IVC
What does Transmyocardial Revascularization (TMR) do?
-Laser creates holes in the myocardium to relieve angina in patients not eligible for bypass or angioplasty
Why would a patient not be eligible for bypass or angioplasty?
Small vessel CAD or no available grafts
2 theories for TMR’s efficacy
- Stimulates angiogenesis (new channels for blood flow)
2. Destroys nerve endings
Anesthetic considerations for TMR
- Has been used in combo with CABG
- Use of a double lumen tube and L lung isolation is required when performed by itself due to L anterior thoracotomy
- Arrhythmias and decrease in CO can be expected, antiarrhythmic prophylaxis should be considered and vasopressors & inotropes should be available
-Fluid around the heart or fluid accumulation in the pericardial cavity
Pericardial effusion
When a pericardial effusion gets large enough to adversely effect heart function (low EF)
Cardiac tamponade
At induction of anesthesia, cardiac tamponade patients are at risk for ____
Severe hypotension and cardiac arrest
Hemodynamic effects of cardiac tamponade
- Decreased CO (dec SV)
- Beck’s triad: hypotension, JVD, muffled heart tones
- Pulsus paradoxus
Treatments for cardiac tamponade
- Pericardiocentesis
2. Pericardial window
GETA is more likely with (pericardiocentesis or pericardial window)
Pericardial window, more invasive
Anesthetic management for pericardial window
- General vs MAC
- Impending tamponade? Is this an emergency?
- Induction in unstable patients: head of bed elevated 45 degrees, use ketamine or etomidate, wait for surgeon to be ready prior to induction
- Avoid bradycardia
- Maintain spontaneous ventilation
If the patient is stable, which approach to pericardial window can be used?
Thoracotomy
If an emergency, which approach to pericardial window is used?
Subxiphoid (can be done under local and sedation)
How do you induce anesthesia for unstable pericardial windows?
- Elevate head of bed 45 degrees to decrease dyspnea
- Avoid propofol, use ketamine or etomidate
- Surgeon scrubbed and dressed prior to induction
When is CO more dependent on HR?
In pediatric patients and cardiac tamponade patients
Why should spontaneous ventilation be maintained during pericardial window?
Positive pressure ventilation decreases venous return and CO
What is a mediastinoscopy done for?
-Obtaining a biopsy to rule out types of cancer
What can happen during mediastinoscopy?
The scope can compress the innominate (brachiocephalic) artery
What does the innominate artery supply?
R arm and R carotid artery
Why is it concerning for innominate artery compression?
If a pt has L carotid stenosis, they are at risk for cerebral ischemia
Anesthetic management for mediastinoscopy
- Single lumen ETT
- A-line in R arm
- SpO2 on R
Primary concern with a mediastinal mass?
Compression of the heart, central blood vessels, trachea and bronchi
Symptoms of compression of heart, central vessels or venous return from SVC
- Decreased CO and potential CV collapse
- Airway edema and potential difficult airway management
- increased ICP
Most common cause of SVC syndrome
Malignancy
What is SVC syndrome?
When a patient shows signs of SVC obstruction from a mediastinal mass
-airway and facial edema, decreased CO, increased ICP
What is Pemberton’s sign?
- Facial congestion, cyanosis and possibly respiratory distress after raising both arms in the air for approximately one minute
- Caused by venous obstruction from goiters or mediastinal masses
True/false: Spontaneous ventilation is better for maintaining airway patency than control ventilation
True
Where should you aim to intubate with a tracheobronchial obstruction?
Distal to the obstruction
What is necessary if you cannot intubate distal to the tracheobronchial obstruction?
-Surgical intervention of tracheal or bronchial stenting with the aid of bronchoscopy and/or jet ventilation
Uses high pressure, provides way for pt to be ventilated through a small catheter
Jet ventilation
Anesthetic management for mediastinal mass (10)
- Order and review diagnostic tests (CT, CXR, ECHO, PFTs)
- Maintain spontaneous ventilation if possible
- Perform an awake fiberoptic intubation in the sitting position if possible if pt is symptomatic
- Consider using an “armored” ETT
- Avoid hypotension and CV collapse if not doing an awake intubation by doing inhalational induction or routine induction
- Have plan for ventilation based on where the obstruction is and how significant it is
- Use semi-upright position for induction and maintenance
- Avoid hypotension to maintain cerebral perfusion pressure
- Place IVs in lower extremities if evidence of SVC syndrome, consider preload augmentations
- Consider need for immediate surgical intervention in case of sudden airway or CV collapse
Associated with significant risks of complications from GA in mediastinal masses
2 or more significant abnormal findings in CT, spirometry or ECHO
What is laser lead extraction used for?
If pacing leads get infected and need to be removed, they are guided over wires to remove tissue surrounding the leads
What can happen during laser lead extraction?
Abrupt, severe onset of hypotension and hemorrhage
