Ischemic Heart Disease II Flashcards
Preoperative Assessment for CABG
- When was the patient’s last MI
- EF
- Angiography results
- Labs
When should the arterial line be placed during a CABG?
Preoperatively/Preinduction
What are the components that can be adjusted with an abnormal cerebral oximeter?
- Hgb
- FiO2
- MAP
- ETCO2
What artery will usually be taken first as a graft in a CABG?
Mammary artery
Considerations for a repeated sternotomy?
- Have blood in the room ready
- Have the bypass machine primed and ready
Ventilation considerations when the pericardium is tacked
Decrease Tidal Volume
Recommended SBP during cannulation
Should not exceed 90-100 mmHg
Heparin dose during CABG
300 units/kg
Prefer ACT if CABG is on pump
ACT >400
Prefer ACT if CABG is off pump
ACT > 300-350
What could prevent the ACT from climbing with repeated doses of heparin?
Intervention?
- AT III deficiency
- FFP can help increase the ACT in cases of heparin resistance d/t AT III deficiency.
- FFP contains AT III which heparin needs to function effectively.
How often does the patient undergo cardioplegia infusion?
20-30 minutes
Temperature goal during bypass
32 degrees Celsius
CMRO2 decreases by how many percent each Celsius?
7% decrease / degree Celsius
What joules should the internal paddles be charged to for defibrillation?
20-30 Joules
SBP for decannulation
90-100 mmHg
Protamine dose to reverse heparin
1 mg/ 100 units heparin
What drug may be used for inotropic support after coming off pump?
Levophed
What are the types of cardio bypass pumps?
- Roller
- Centrifugal (adults)
What should the pump be primed with if a patient has renal failure and a Hgb of 7?
Primed with albumin and PRBC
What are pumps typically primed with?
Crystalloid
Can also be primed with albumin, PRBC, lytes, mannitol, and heparin
What is the average prime volume?
1500-2500 mL
Range of Hct on pump
17-25%
What three routes can cardioplegia be administered?
- Antegrade: Aortic Root
- Retrograde: Coronary Sinus
- Bypass graft
Pulmonary complications of cardiopulmonary bypass
- Acute Lung Injury (“Pump Lung”)
- Diffused congestion
- Alveolar and interstitial edema
- Hemorrhagic Atelectasis
CNS complications of cardiopulmonary bypass
- Stroke from emboli
- Hypotension causing confusion (“Pump Head”)
GI complications of cardiopulmonary bypass
- Hypo-perfusion can embolize the mesentery artery, causing a mesenteric infarction.
- HITT
What factors can cause renal complications of cardiopulmonary bypass?
- Duration on pump
- Excessive blood loss
- DM
- Use of pressors
- Advanced age
Preferred urinary output during a CABG
1 ml/kg/hr
MOA of TXA (Cyclokapron)
Anti-fibrinolytic that inhibits the activation of plasminogen
Off pump coronary artery by pass is most successful with a normal ______.
EF (50-70%)
Which vessels are grafted first during OFF pump bypass?
- Aorta first (proximal fist)
- Then distal (will need vasopressor support)
Which vessels are grafted first during ON pump bypass?
- Distal first
- Then proximal
For off pump CAB, ACT is done by anesthesia every _____ minutes and redose heparin prn.
20 minutes
When will cardiac transplantation be indicated?
End-stage cardiomyopathy
Anesthetic issues w/ cardiac transplantation
- Denervated heart (vagus nerve has been cut)
- S/E of immunosuppressive therapy
- can develop CAD
Considerations for Denervated Hearts?
- No sympathetic innervation (No HR change to DL, Pain, HOTN)
- No parasympathetic innervation (Runs ST, cardiac dysrhythmias)
- No sensory ability
Immunosuppressives considerations for cardiac transplantation.
Must be continued during preoperative period
Effects of immunosuppressives on NDMR.
Enhance neuromuscular blockade
Concerns of immunosuppressives and gingival hypertrophy
Can cause bleeding into the airway
Concerns of immunosuppressives with seizures thresholds
- Can decrease seizures threshold
- No Hyperventilation
Hypocapnia raises the neuronal excitability by alkalinizing the extracellular environment, which can provoke or worsen seizures.
Anesthesia considerations for cardiac transplantation.
- Maintain preload (SVV/vigileo/echo)
- Avoid vasodilation (GA vs SAB/epidural)
- Continue pacemaker
Two most common views of an echocardiogram
- Transverse 4-chamber view
- Transgastric short axis view
Contraindications for TEE
- Esophageal stricture
- Esophageal masses
- Recent bleeding from esophageal varices
- Zenckers diverticulum
- S/p radiation to neck
- Recent gastric bypass surgery/ gastric band
Where in the heart will most of the clot be in a patient with atrial fibrillation?
Left atrial appendage
Types of replacement heart valves
- Bioprosthetic
- Mechanical
- Polymer
What are bioprosthetic valves made out of?
Porcine or bovine
How long do bioprosthetic valves last?
- 10-15 years
- Ideal for older patients (80-85 years)
What is the thrombogenic potential of bioprosthetic valves?
- Low thrombogenic potential
- No need to be on anticoagulants
What are mechanical valves made out of?
Metal or carbon alloy
How long do mechanical valves last?
- 20-30 years
- Ideal for younger patients (30-50 years)
What is the thrombogenic potential of mechanical valves?
- High thrombogenic potential
- Will need to be on routine anticoagulants
Risk factors for Mitral Stenosis.
What is the most common risk factor?
- Rheumatic Fever (most common)
- Female
- RA
- SLE
- Stenosis s/p repair
Patho of Mitral Stenosis
- Diffuse thickening of mitral leaflets
- Calcification of annulus and leaflets
- Occurs very slowly (20-30 years)
What problems are developed from Mitral Stenosis?
- CHF
- Pulmonary HTN
- Right heart failure
Sx of Mitral Stenosis
- Obstruction of LV diastolic filling
- ↑ LA volume and pressure
- ↑ Pulmonary venous pressure
- DOE
- Orthopnea
- Paroxysmal Nocturnal Dyspnea (PND)
What distinct feature can be seen on a CXR for someone with mitral valve stenosis?
Left atrial enlargement on CXR
What distinct feature can be seen on an EKG for someone with mitral valve stenosis?
- Broad notched P-waves (LAE on EKG)
- A-fib common
Desired HR for Mitral Stenosis
Sinus rhythm
Treatment for Mitral Stenosis
- Diuretics to ↓ LAP
- HR control if A-fib develops
- BB, CCB, Dig/combo
- Anticoagulants (7-15% risk/yr for stroke)
- Balloon valvotomy/ commissurotomy/ replacement
Treatment for patient w/ Mitral Stenosis in A-fib RVR.
- Cardioversion
- Amiodarone
- BB/CCB/Digoxin
What factors can increase central volume in mitral valve stenosis?
- Excessive fluid administration
- Tredelenburg position
- Uterine contractions
Avoid these things in mitral valve stenosis.
SVR consideration for mitral valve stenosis
- Avoid ↓ SVR
- Body will respond to ↓SVR w/ tachycardia, which will worsen CO
- Need adequate afterload, consider phenylephrine/ vasopressin
Mitral Stenosis Pre-Op Considerations
- Caution with sedatives, more susceptible to ventilatory depression
- No anticholinergics (Rubinol)
- Continue HR control drugs
Mitral Stenosis Induction/Maintenance Considerations
- Avoid tachycardia (No Ketamine, Pavulon, Histamine releasers)
- Have short-acting BB on hand
- Avoid light anesthesia
- Reverse gently
- Care with excessive fluids
Why would you want to avoid hypoventilation-induced respiratory acidosis in mitral valve stenosis?
- Tachycardia
- ↑ PVR
Causes of Mitral Regurgitation
- Endocarditis
- MV Prolapse
- LVH
- Papillary muscle dysfunction
- SLE
- Rheumatoid arthritis
- Ankylosing spondylitis
- Carcinoid syndrome
Normal size a of mitral valve
4-6 cm2
Mitral valve stenosis size
<1.5 cm2
Patho of Mitral Regurgitation
- Decrease forward LV stroke volume
- Regurgitatant fraction > 0.6 (severe)
- LVH
Regurgitant fraction is dependent on these factors:
- Size of MV orifice
- HR
- Pressure gradient (LV compliance and impedance to LV ejection)
Dx of Mitral Valve Regurgitation
- Holosystolic apical murmur, radiates to axilla
- Cardiomegaly
- LA enlargement and LV hypertrophy on EKG
Treatment of Mitral Valve Regurgitation
- Avoid bradycardia
- Avoid acute afterload increases
- Digoxin
- Vasodilators…ACE inhibitors
- Biventricular pacing
FAST FORWARD FULL
Indicators for early mitral valve replacement for MR.
- EF < 30%
- Regurgitant SV > 65 mL
Why is MV repair preferred over replacement for Mitral Valve Regurgitation?
Maintain normal LV ejection anatomy
Anesthesia goals for MR
- Prevent and treat ↓CO
- Improve forward LV SV with afterload reduction
- Maintain normal to slightly high HR
- Foward, Fast, Full
Mitral Regurgitation Induction/Maintenance Considerations
- Avoid excessive narcotic-induced bradycardia
- Use etomidate (min myocardial depression/ min SNS activity)
- VA to ↓ SVR
- Maintain adequate volume
- Neuraxial technique to decrease afterload
Patho of aortic stenosis
- Disease of age
- Caused by degeneration and calcification of leaflets
- Associated with hypertension and hypercholesterolemia
- Obstruction to ejection from LV into aorta
- LV Pressure increases/ workload increases
- Myocardial O2 delivery decreases
When will aortic stenosis occur if a patient has congenital bicuspid aortic valves?
Earlier in life (30-50 years)
Normal size of aortic valve
2.5-3.5 cm2
Size of severe aortic valve stenosis
<0.8 cm2
Sx of aortic stenosis
- Angina
- Syncope
- DOE
- Systolic murmur that radiates to neck (mimics carotid bruit)
- LVH on EKG
Aortic Stenosis mortality rate within 3 years
75%
Treatment of Aortic Stenosis
- May delay replacement until symptomatic
- Balloon valvotomy useful in young adults
Anesthesia goals for aortic stenosis
- Similar to Mitral Stenosis
- Maintain normal HR
- Maintain normal volume and afterload
- Cardiac arrest victims very difficult to resuscitate with severe AS
Aortic Stenosis Induction/Maintenance Considerations
- Do not decease SVR
- Avoid tachycardia (no ketamine)
- Treat HOTN with alpha agonist (phenylephrine)
- Treat Bradycardia (glyco, atropine, ephedrine)
- Treat Tachy dysrhythmias
What device can help distinguish hypovolemia from heart failure in aortic stenosis?
Pulmonary artery catheters
Causes of Aortic Regurgitation
- Endocarditis
- Rheumatic fever
- Bicuspid aortic valve
- Aortic dissection
- Marfan’s syndrome
- Anorexigenic drugs (drugs that reduce food intake)
Pathophysiology of AR
- Decrease in CO
- Pressure and volume overload of LV
- LV typically compensates for increased volume
The amount of Regurgitant in AR is dependent on these two factors
- HR
- SVR
Dx of AR
- Diastolic murmur radiates to the right sternal border
- Widened pulse pressure
- LV dysfunction…fatigue, dyspnea, coronary ischemia
- LVH on EKG
- Abnormal echo
Asymptomatic mortality of AR
0.2%
Symptomatic mortality of AR
10%
Anesthetic goals for AR
- Maintain Forward, LV SV
- HR around 80
- Prevent abrupt increase in SVR
- Maintain contractility
- FAST, FORWARD, FULL
Aortic Regurgitation Induction/Maintenance Considerations
- Prevent extreme bradycardia
- Volatile anesthetics awesome at ↓ SVR
- Maintain fluid volume to support preload.
- FAST, FORWARD, FULL
Should anticoagulants be continued for minor surgery if the patient has a mechanical valve?
Yes
Coumadin/ Direct thrombin inhibitors should be discontinued how many days before preop?
- 3-5 days
- Lovenox instituted for major surgery
What will be given post-op to patients w/ mechanical valves until oral anticoagulation is adequate?
Heparin
Preop abx should be given to patients with mechanical valves to prevent _________-
Bacterial endocarditis
What is A?
Normal heart sound
What is B?
Aortic Stenosis
Systolic murmur that radiates to neck, excess vibrations d/t narrowed valve that increases blood velocity, small diameter, loudest heart sound, more turbulence
What is C?
Mitral Regurgitation
Blood will move in the wrong direction during systole, resulting in a holosystolic apical murmur radiating to axilla
What is D?
Aortic Regurgitation
When there is high pressure in the aorta and low pressure and volume in the ventricle, blood will flow back to the LV during diastole. Causing a diastolic murmur radiating to the right sternal border.
What is E?
Mitral Stenosis
Diastolic murmur, due to blood flow through the narrowed valve, filling issue. The diastolic murmur is louder towards the end d/t atrial contraction
What is F?
Patent Ductus Arteriosus
Diastolic and systolic murmur present, there is blood flow going from the aorta (100 mmHg) to the pulmonary artery (16 mmHg)