Cardiac Flashcards
What are you looking for on an echo?
EF, valve function, wall abnormalities, calcified aorta (think cannulation), atrial thrombus (think CVA)
an intraop MI for a cardiac surgery patient
50 % mortality
what are you looking for on a CXR?
-calcified aorta, cardiomegaly, edema
What are comorbid conditions commonly seen w/cardiac patients?
PVD (carotid?), DM, HTN, COPD, renal (this one increase post-op mortality)
What do you continue until DOS?
antiarrhythmics, CCBs, BB, nitrates
Baseline Labs (4)
PT, PTT, ACT
Platelet # & function (TEG)
Renal + Liver function
T&C (4 units PRBCs)
Four cardiac anesthesia goals
decrease MVO2
maintain oxygen
anticoagulation
BP managment
How do we decrease MVO2?
anesthesia, hypothermia, electrical silence w/cardioplegia, empty cardiac chambers (esp. LV)
how do we Maintain oxygen supply
Maximize oxygen carrying capacity + flow
Hemodilution and acceptable perfusion pressure
Three myocardial protection strategies
cardioplegia
hypothermia
hemodilution - increases flow by decreasing viscosity
Cardioplegia induced asystole
all electrical & mechanical activity ceases
- Potassium given continuously during cross clamping
- May be primed w/blood versus clear prime
- Hyperkalemia is a risk w/renal patients
The effects of hypothermia
- Alters platelet function and reduces fibrin enzyme function
- Inhibits initiation of thrombin formation
- Reduces metabolic demands and increases tolerance to ischemia
Name the CABG order of events
o Monitors, Lines, Induction o Wait (no stimulation) o Incision o Drop Lungs o Sternotomy o Surgical dissection (minimal stimulation) o Cannulation o On-Bypass o Off Bypass o Dry up – Give protamine o Close Chest
What monitors do you need? (4)
pulse ox on ear or nose
pacemaker
TEE
Swanz Ganz
What does TEE do?
o Helps diagnose underlying mechanisms ascribed to multiple scenarios
o Evaluates preload (ventricular filling) do we give volume?
o Estimates CO
o Assess ventricular systolic function + ventricular diastolic function
o Valvular pathology, calcified aorta
o Cardiac tamponade
o Atrial thrombus
o Air in the heart
o Re-examine graft
TEE C/I
esophageal varices, full stomach
Swanz Ganz
Placed in the right IJ via cordis
- Swan has entered PA when DBP increases compared to RV
- 15-30/0-8 (RV)
- 15-30/5 – 15 (PA)
- 10 (wedge)
Complications w/Swan
- Ventricular arrhythmias
- Heart block (esp. if pre-existing LBBB) b/c you don’t want to interfere with the Bundle of His on the right
- Pneumothorax (esp. with subclavian)
- Arterial puncture (most common acute injury)
- Hematoma/thromboemboli
- Vascular injury (localized hematoma, minor, & most common)
- Valve damage (rare – can happen if balloon is not down when pulling)
- PA rupture
- Perforation of thorax leading to hemothorax (BAD)
- Cardiac tamponade (most common life-threatening complication of CV cannulation)
- Blood stream infection
Nitro gtt
- Nitro primed plugged into central line
- (25 mg in 250 mL bottle = 100 mcg/mL) runs at 0.2 – 1.5 mcg/kg/m OR 5 – 200 mcg/m; titrate Q3-5 minutes
- MOA: venous dilator > arterial dilator; relaxes peripheral VSM by donating an NO group. Reduces cardiac oxygen demand by decreasing preload. Dilates CA and improves collateral flow to ischemic regions to help prevent vasospasm.
Epi > NE
- Epinephrine affects alpha, beta1, and beta 2.
- Use 1: 1,000 (1 mg/mL) in 1 mL ampule and add 1 – 4 ampules into a 250 mL bag of NS. (4 mcg – 16 mcg/mL)
- Dosing: 1 – 16 mcg/min
Phenylephrine
Neo gtt primed 10 mg/250 mL NS = 40 mcg/mL plugged into central line
Dopamine
1 - 20 mcg/kg/m
Renal 1-5 * Cardiac 2 – 10 * VC 10 – 20
gtt primed (esp. if EF < 40%) use for coming off pump
Dobutamine
2.5 – 20 mcg/kg/m
Antiarrhythmics
esmolol, lidocaine, magnesium, amiodarone
esmolol + mg dosing
Esmolol – SVT (0.5 – 1 mg/kg over 1 minute); 50 – 250 mcg/kg/m
Magnesium 2 – 4 grams (give after aortic clamp, good membrane stabilizer)
Heparin
30 – 50 K units in a 60 cc syringe (1,000U/mL or 10 mg/cc) (dose = 300 units/kg)
DOA: 150 minutes
protamine
(10 mg/mL) in a 30 cc syringe (10 mg of protamine for every 1,000 units of heparin)
Why do we give TXA?
We use the TEG to monitor fibrinolysis b/c large amounts of circulating tPA are found during CPB leading to increased post-op bleeding. This is due to inappropriate fibrinolysis. Drugs exist to inhibit the binding of plasminogen to fibrin (a step in the fibrinolytic pathway). To be effective must be started prior to going on CPB.
Calcium Chloride
(100 mg/mL) in a 10 cc syringe
500 mg dose for hyperkalemia
Pre-Induction Patient Prep
NC \+/- mild sedation (fent.) PIV x2 A-Line Baselinee: ABG, ACT, T&C Defibb pads
Propofol
safe in patients with ischemic and valvular heart disease; biggest challenge is hypotension
o 50 mg increments at a time; note there will be a slow circ time
what IA do you avoid
nitrous
post-induction (4 actions)
central line
OG
TEE
tuck arms
VA
produce dose dependent global cardiac depression. Alters the intracellular calcium and sensitizes the myocardium to the effects of epinephrine
o Prevent or facilitate atrial or ventricular arrhythmias during myocardial ischemia or infarction
o Produce weak coronary artery dilation and depresses baroreceptor reflex control of arterial pressure
o Usually, isoflurane is used by the perfusionist, no desflurane b/c tachycardia
Pre-Incision
- Hypotension d/t lack of stimulation. There are risks involved if you use vasoconstrictions.
- Recall is rare at this point unless severe hypotension occurs in the face of purely opioid technique
Incision
- Intense surgical stimulation = HTN
o Deepen anesthetic, NTG/NTP - Handling of the heart by the surgeon to identify and localize ischemia (arrhythmias + hypotension common)
- Significant bleeding
- Drop lungs for sternotomy (actually d/c from the circuit)
- Arterial & saphenous veins are harvested
- Once the chest is open, you will see RV on the screen. The LV is behind the heart (unable to see)
Pre-Bypass HD
keep the blood pressure +/- 20% of baseline pressure. HR 40 – 80
Heparin MOA
Pre-Bypass
MOA: binds to antithrombin III and potentiates its natural anticoagulant properties (1000x)
Heparin dosing + onset
300 – 400 units/kg
– wait 3-5 minutes for activated clotting time (ACT)
ACT & Heparin
Normal ACT = < 130 (80 – 120)
CPB ACT > 400 – 450
Heparin ADR
- SVR & BP can drop by 20%
- AT III deficiency patient unresponsive to heparin, give FFP or thrombate III
- HIT – antiplatelet antibodies which leads to platelet aggregation and potentially life-threatening thromboembolic events (platelet < 100,000). This is r/t being exposed to heparin before**
Name a few things you need to do BEFORE cannulas in
- Heparin must be given
- Medicate w/midazolam + fentanyl.
- Dump foley for fresh UO
- The patient is passively cooling in the OR, be sure to avoid atrial fibrillation w/cooling because of LV swelling
Name some frequently encountered problems pre-bypass
- Arrhythmias r/t cardiac manipulation and cannulation. This may be the first sign of MI (watch your ST segments)
- HTN: especially during aortic cannulation
- HoTN: volume or pressors through aortic line
- Heart failure
- Bleeding: sternotomy lacerates RV or aorta
Arterial cannulation
- aorta
- Drop the BP for aortic cannulation (SBP < 90) to avoid dissection. This is done first so the perfusionist can give volume if needed.
- NTG or nipride to drop the BP
- Be looking at TEE for calcium or plaques b/c you need to notify surgeon of this
Venous cannulation
BP will drop &/or arrhythmias will occur when placing
Coronary sinus cannulation
Will see a drop in BP. This is for retrograde cardioplegia
what is an LV vent for
to drain the thebesian and bronchial veins so the heart does not swell.
Where is anterograde catheter?
proximal to cross clamp
also place a retrograde one (in coronary sinus) if anterograde is not enough!
Surgeon says… go on bypass.. then what? (6)
The perfusionist will open the venous clamp and blood drains passively into venous reservoir
- cool patient
- Arterial tracing goes flat – but EKG still present
- Pull back PAC 2 – 3 cm so it is not in PA (don’t want it to lodge, obstruct, or puncture).
- Look at head to ensure there is no swelling (this would indicate venous catheter is improperly placed).
- Check pupils & BIS
Heart is empty - now what?
stop the ventilator. They may say ‘we are at full flow, stop the ventilator’
- Stop the fluids.
- Stop IA.
*Perfusionist runs IA, phenylephrine, nitroglycerin
What is full flow
*Full flow = 2.5 – 3 L/m or 50 – 60 mL/kg
Goals during CPB
- CVP 0 – 5 or (-)
- MAP 65 – 70 (unless it’s a valvular case, then 50 – 60 is ok)
- SVO2 70 – 80% (if there is a major decrease, give more paralytic)… Ensure no shivering
- Provide amnesia with versed
- Cerebral Oximetry will decrease once on CPB, but a major drop (i.e., 80 - 20) is concerning as it may indicate cannula malposition
CPB priming
1500 – 2500 mL of balanced electrolyte solution.
-Albumin, heparin, mannitol (diuresis & free radical scavenging), and bicarbonate is added to increase osmolality, reduce edema, and promote diuresis
+/- corticosteroid and blood products
- Once venous is cannulated, aspirate blood, prime w/blood + solution
- Dilution of catecholamines will occur with priming
Ideal Hct
20%
- Hemodilution is associated w/decreased viscosity, decreased SVR, and promotion of blood flow to tissues
- A decrease in viscosity = increase in flow (be mindful there is already an increase in viscosity d/t cooling)
how often is abg/act drawn?
q30m by perfusionist
cardioplegia solution
*4 degrees C (reduces metabolism of the heart, V-Fibb occurs at 25 – 30 degrees C)
-Contains K+ to depolarize the heart (26 mEq/L)
o Glucose 43.9 gm/L
o Mannitol 12.5 gm/L
o Sodium bicarbonate 2.67 mEq/L
o Solu-Medrol (methylprednisolone sodium succinate) 1 g/L
o Normosol-R
pH 7.6
mOsm = 480
how do we ensure cardioplegia solution does not leak into circulation?
Once the patient arrests, the perfusionist drops the flow, the surgeon cross-clamps the aorta.
Complications r/t CPB
o Hypotension r/t decreased SVR and heart handling
o Renal ischemia from hypo-perfusion and hemodilution (A decrease in UO is not indicative of renal injury postop)
o CVA from thrombus in CPB system, air emboli
o Thrombocytopenia
o Increased inflammatory response (Extrinsic and intrinsic coagulation pathways are activated)
o Pump-head
risks for postop renal damage
CBP > 1 hour, pre-existing renal disease, increased age
ways to protect brain during CPB
hypothermia, blood gas management, adequate BP, cerebral oximetry, BIS.
Biggest culprit = emboli!!
how to help w/SIRS
Stress response is evident w/increased catecholamines, AT II, and free radicals
Statins may help
Re-warming
HIGH RECALL RISK d/t vasodilation and hypotension
when do you start warming?
the surgeon is sewing the last distal graft OR PRIOR TO AORTIC CROSS-CLAMP REMOVAL OR WHEN KNOTS ARE BEING TIED DOWN
how long to re-warm
30 – 40 minutes to rewarm b/c damage may occur if it is done too quickly.
o 1 degree Celsius Q3-5 minutes
Preparation for Coming off Bypass
Core temperature > 35C (target = 37C) Correct labs (ABG, K+, Acid-Base, Hct) o High K+ = 500 mg CaCl o Magnesium = 2 – 4 g (prevent a-fibb) o Hct = 20 – 25% goal o Cell Saver o Blood sugar < 200 - Inflate lungs (de-airing maneuvers) o Position changes o Manual ventilation - Removal of cross clamp and hot shot given (warm cardioplegia – K+ to restart the heart) - Defibrillation if heart does not res-start at 10 – 30J with sterile pads - Heart rate: pace at 80 – 90 o Usually v-paced b/c atrial wires are harder to remove
what is termed off-bypass
When the pump comes off and the venous cannula is clamped
off-bypass.. now what?
- Measure CO, watch TEE, PA, A-Line
- Monitor SVO2: increased demand? Decreased delivery?
- Shivering? Paralyze
- Turn on the ventilation, manually recruit? Just be careful b/c internal mammary graft (aka internal thoracic graft) will rupture… thus keep PIP < 30 mmHg
- IVF + VA
CPB ADRs
- Prolonged cross-clamp time significantly correlates w/major postoperative morbidity
- When the cross clamp comes off, reperfusion may paradoxically cause myocardial damage and limit the extent of recovery.
- Complications include hemorrhage at CPB, dislodgement of clots, and aortic dissection
- ST elevation may be indicative of air in the heart. Notify surgeon. Examine TEE.
post CBP assessment
o Contractility: look at the heart, how is it filling? How is it beating? We need adequate contractility to come off bypass.
o Inspect for bleeding
o Systemic pressure in relation to PA pressure
when can you give protamine?
- WHEN ALL CATHETERS OUT + PATIENT IS STABLE + SURGEON SAYS ITS OKAY … you can give protamine SLOWLY through PIV
protamine dosing
1mg/100U of heparin or 2 – 4 mg/kg
if ACT > 150 give
protamine half life
30 - 60 m (shorter than heparin BTW)
what is protamine
composed of multiple low molecular weight proteins that are derived from salmon sperm. It is able to neutralize and reverse effects of heparin, so heparin cannot form a complex with AT III.
-Has anticoagulant effects at levels 2 – 3 x normal reversal dose (weak anticoagulant at normal levels)
protamine ADR
Type I reaction = histamine release resulting in hypotension (just give volume & VP)
Type II reaction = IgE (anaphylactoid)
Type III reaction = lodging in pulmonary circulation resulting in pulmonary HTN
chest closed..
- When the chest is closed, the heart is squished and hypotension ensues. The team may have to open back up if patient does not tolerate it.
o Low CO and high BP – maybe inotrope? Milrinone?
Post CPB Challenges
- Recall + neurocognitive changes (emboli?)
- Bleeding d/t loss of clotting factors, fibrinolysis, thrombocytopenia, surgical blood loss, vessel trauma, metabolic byproducts
- Organ hypo-perfusion
- Non-pulsatile blood flow, emboli, thrombi
- Systemic inflammation response
- Residual hypothermia
- Remember, extended CPB and cross-clamp time makes it hard to wean off CPB
Reperfusion interventions
- Spend time paying back by re-perfusing the empty heart at adequate perfusion pressure (20 – 30 minutes). This allows the heart time to recover by washing out metabolic products.
- Consider IABP if long clamp time.
- Correct metabolic abnormalities.
what do you need for transport
- Ambu bag, oxygen tank
- EKG, a-line
- Emergency drugs = epinephrine, paralytic, propofol, dex drip
- Once you move the patient to the other bed, check breath sounds
- The surgical table is sterile until we leave the room
- Once in ICU, attach to ventilator and re-check breath sounds
- Oxygen stays at 100% until first ABG
HD for Aortic & Mitral Stenosis
maintain preload + SVR; HR 50 – 80 (lower = better)
HD Aortic & Mitral Regurgitation
maintain preload; drop SVR; HR 50 – 80 (higher = better)
Highest rates of recall
- Graft harvest
- Sternotomy
- Re-warming
Heart transplant recipient considerations
Priority status, ABO, Body size match, Distance from donor site (b/c only lasts 4 – 6 hours)
selection for recipients
o Typical recipient = NYHA Class IV with a predicted life expectancy < 12 months, EF < 25%
o Usually has a VAD
o Most common indication: idiopathic cardiomyopathy
Contraindications for the recipient for heart transplant
o > 70 years old
o Chronic renal dysfunction
o Obesity
heart transplant patient induction
RSI b/c full stomach
- Lines prior to induction.
- smooth, rapid control of airway
- Slow administration of medications
- Maintain HR and intravascular volume
- Avoid a drop in SVR
intraop heart transplant
adhere to immunosuppression protocol; high dose steroid & immunosuppressant drug
- Gtts: DIRECT ACTING AGENTS!! (Isoproterenol, epinephrine, phosphodiesterase inhibitors (milrinone), nitric oxide, inhaled prostaglandins)
- Vasopressin preserves SVR w/o effecting PVR
Inability to wean from CPB for heart tx sx
(likely right heart failure)
Post Heart Transplant
Denervation of donor heart during retrieval
(why we need direct acting agents on myocardial adrenergic receptors)
o Loss of PSNS = faster resting HR
(Still reverse w/neo & glyco)
o Direct acting vasoactive agents (inotropes and vasoconstrictors)
o Volume dependent (preload dependent); Frank Starling mechanism still functions
o Accelerated atherosclerotic disease = no angina s/s (arrhythmia is indicative of ischemia)
how is an off pump CABG done?
- Immobilization of the heart by compression &/or suction
- a sternotomy is still done
- The bypass is on standby in the room
- If the suction is placed on the RV, be mindful the RV is very thin walled and can compress the native coronary flow.
- TEE & heparin are still used
how to prevent hypotension and reduced coronary artery perfusion during off pump cabg
o Volume load
o Head down
o Vasopressors
Minimally Invasive Direct Coronary Artery Bypass
- Grafting of a single vessel; LIMA to LAD
- Robotic off pump case with bypass on standby
- Left anterior thoracotomy incision
- OLV
-heparin oh ya
!!Defibb pads prior to draping!!
Other techniques for Minimally Invasive Direct Coronary Artery Bypass
right thoracotomy, parasternal, CBP through femoral artery + veins
HD for minimally invasive direct coronary artery bypass
o Keep HR low to keep MVO2 low
o Increase preload
o Drop TV if not isolating one lung
Mini AVR & MVR Procedures
- DLT for lung isolation
- Femoral cannulation
- Transvenous pacing – placed & tested
- Pads on
- Central venous access
TAVR/TAVI
- Femoral artery or transapical (apex of left ventricle)
TAVR technique
- Anesthetic Technique: IVA or GETA
o Large bore IV
o A-Line
o Central access
TAVR monitors
o TEE (GA) or TTE (transthoracic echo)
o External defibrillator pads (R2 pads)
o Fluro for lines
o Pump on standby
TAVR risks
stroke, RF, cardiac rupture, tamponade
what are blood conservation strategies for cardiac surgery
o Antifibrinolytic drugs
o Cell saver, POC testing to support transfusion
o Minimize hemodilution (normovolemic hemodilution)
o Retrograde priming of pump w/autologous blood
Platelet function is lost/altered by:
Hemodilution, hypothermia, contact w/CPB circuit
why does RV dysfunction or failure occur post CPB
because of inadequate myocardial protection or inadequate revascularization w/resultant right ventricular ischemia
How to reduce the inflammatory response w/cardiac surgery
o Modification of surgical and perfusion techniques
o Circuit components
o Pharmacological strategies
causes of CNS insults
micro emboli, hypoperfusion, and SIRS
but < 2% now yay
post op renal dysfunction risks
o T1DM
o Renal insufficiency
o Vascular pathology
o Nephrotoxic agents
ADR of sternotomy
a significant reduction in TLC, VS, and FEV
