Cardiac I Flashcards

Question 1

Q

Preop eval of cardiac patient

Answer

A

Cardiac:
- Severity of disease/hemodynamic status
- Degree of impairment of contractility
- Development of compensatory mechanisms
- Exercise tolerance
- Hx of CHF, or MI-ST segment changes
- Angina
- Dysrhythmias
- Compensatory increase in sympathetic nervous outflow, ie Hr, anxiety, diaphoresis
- Hx of previous surgery
Pulmonary
- COPD
Renal
PVD-especially carotid disease
Diabetes
Obesity

Question 2

Q

Laboratory data for cardiac patients?

Answer

A

CBC
Electrolytes
Cardiac Enzymes
Serum Creatinine
Coagulation profile
Type and Cross

Must have PRBCs available

Question 3

Q

Lab data for MI?

Answer

A

Peak A, early release of myoglobin or CK-MB isoforms after AMI

Peak B, cardiac troponin after AMI

Peak C, CK-MB after AMI

Peak D, cardiac troponin after unstable angina.

The most recently described and preferred biomarker for myocardial damage is cardiac troponin. (gold standard)
Absolute myocardial tissue specificity
High sensitivity
Thereby reflecting even microscopic zones of myocardial necrosis.
- will see peak even after only angina

Apex-

CKMB
- initial elevation 3-12 hours
- peak 24 hours
- return to baseline 2-3 days
Troponin I
- Initial 3-12 hours
- Peak 24 hours
- return 5-10 days
Troponin T
- initial 3-12 hours
- peak 12-48 hours
- returnto baseline 5-14 days

Question 4

Q

Other cardiac testing you may want to evaluate before cardiac surgery?

Answer

A

Catheterization data
- LVEDP
- EF
- CI
Echocardiography data
- EF
- Wall motion abnormalities
Chest X-Ray
- Cardiomegaly
- Pulmonary vascular congestion, edema, effusion
Angiography
EKG
- Ischemia/infarct

Question 5

Q

What cardiac drugs should be continued DOS?

Answer

A

The following should be continued until the operative day:

*Antiarrhythmics
- •Amiodarone-special concern (1/2life 30d)
*Ca+ Channel blockers
*Β blockers
*Nitrates

Question 6

Q

Premedication/anxiolysis prior to cardiac surgery?

Answer

A

Explain operative course and postop to the patient

Premedication

Narcotics

Anxiolytics

Antibiotics

n

Question 7

Q

Monitors used for cardiac surgery?

Answer

A

Pulse Ox
TEE
EKG
- Leads V5 & II
Temperature
ABP
- Usually radial, sometimes femoral
CVP
- Mandatory for infusion of drugs
PA Catheter
- Pts with severe LV dysfunction
- Pts with profound pulmonary HTN

Question 8

Q

TEE use in cardiac?

Answer

A

Intermittent pulses with a frequency of 2.5-7.5 MHz.
Can determine:
- Preload
- Hypotension
- CO
- LV Filling Pressures
- LV contractility
- LV afterload
- Ischemia, emboli, valvular pathology
- Assessment of surgical repairs

Question 9

Q

Cardiac OR setup?

Answer

A

Usual airway equipment/machine check
Pacemaker
Drips
- Vary b/w institutions
- Most commonly:
  - NTG/NTP
  - Epinephrine/Norepinephrine
  - Phenylephrine/Ephedrine
  - Dopamine/Dobutamine as needed
  - Antiarrhythmics (esmolol, lidocaine, mag, amiodarone)
Heparin-and coag. monitoring capability
Emergency drugs
PRBC available in OR

Question 10

Q

Anesthetic agents for cardiac?

Answer

A

Opiods
- Fentanyl 50-100mg/Kg
- Sufentanil 10-20mg/Kg
Inhalation Agents
- Forane
- N2O
Induction Drugs
- Etomidate
- Benzodiazepines
- NM Blockers
  - Pavulon
  - ED95 dose Vecuronium

Question 11

Q

Preinduction period for cardiac surgery?

Answer

A

Evaluate need/effectiveness of premed
Preoxygenation
Monitor placement
Large-bore Ivs
Invasive monitors
- •In some institutions preinduction vs post
- •In severe disease –> preinduction

Question 12

Q

Goals of induction and intubation of cardiac patient?

Answer

A

Smooth induction
- Avoid cough, larygospasm, truncal rigidity
- Avoid hypo- or hyper- tension
Deep plane of anesthesia
Short duration laryngoscopy
Tape tube, eyes
Pad pressure points
Check monitors in this busy period

Question 13

Q

Considerations for pre-incision period of cardiac surgery?

Answer

A

Hypotension
- Lack of stimulation
- Systemic pressure support
- Risks involved with vasoconstrictors
- Recall rare at this point, unless severe hypotension occurs in the face of purely opiod technique

Question 14

Q

Considerations for incision to bypass period

Answer

A

Intense surgical stimuli → STERNOTOMY
- Hypertension
  - Deepen the anesthetic
  - Narcotics (PAINFUL)
  - Vasoactive agents
    - NTG/NTP
- Sternotomy
  - Drop lungs
    - Disconnect circuit from ETT/vent (lungs will deflate)
Heart Handling by surgeon
- Communication is of the utmost importance
  - Arrythmias/HoTN common
- Bleeding can be significant
- Identifying and localizing ischemia
- Arterial and Saphenous veins are harvested

Question 15

Q

Considerations around the administration of heparin prior to initiation of bypass?

MOA of heparin? Dose? Peak?

Answer

A

Anti-coagulate the pt with Heparin

MOA:
- Binds to antithrombin 3 (AT3) and potentiates its natural anticoagulant properties
Dose: 200-300units/kg
Peak: 2 mins
- 3 min → Check activated clotting time (ACT)
  - Normal ACT = < 130 seconds (70-110 average)
  - Heparinized ACT = 350-500 seconds acceptable (> 400-450)
    - *Safe to go on bypass
- Administered through CVP or directly into RA

Considerations:

SVR & BP can ↓ by 10-20%
- D/t blood viscosity reduction
  - While blousing → monitor for HoTN and tx
ACT checked after 3-5mins
- (Should be > 300-400 sec)

Question 16

Q

What are some special cirucmstance that would interfere with heparinization?

Answer

A

Special circumstances that interfere with heparinization- Examples: ACT may not increase

Antithrombin III deficiency
Long term heparin therapy
Excessive hemodilution
- min fluids → interferes w/ heparinization
Heparin-induced thrombocytopenia
- Antibody mediated response
NTG long term
- Heparin resistance?
Alternatives to increase ACT:
- FFP
- Thrombate III
  - Scenario: Appropriate heparin dose admin and ACT doesn’t increase appropriately → admin thombate III or FFP, then wait, then give additional dose of heparin and check ACT
  - NEVER go on pump unless appropriate ACT

Question 17

Q

What cannulations are performed to initiate CPB

Answer

A

Bypass:

Aorta (Arterial side) → brings O2 rich blood to systemic circulation
RA (venous side) → brings O2 blood back from systemic circulation

Cannulation

1^st→ Aortic cannulation (Arterial side): must DROP BP!! (esp if calcified)
- Can cause aortic rupture!
- Ex: SBP 90-100
  - Cannulated 1^st bc perfusionist can rapidly admin fluids through arterial line in case BP drops
2^nd → RA cannula (venous side):
- BP might drop &/or arrhythmias can occur while placing
3^rd → Cannulation of the coronary sinus for retrograde cardioplegia to arrest heart
- Anatomy: Coronary sinus is where coronary vessels empty into to get reperfused
- Retrograde cardioplegia- providing poor RV myocardial perfusion, stopping the heart
  - Cannulation → similar effects as RA (severe ↓ BP)
    - Tx: Fluids by perfusionists, vasoactive agents
*Medicate pt w/ extra Midaz and Fentanyl right before going on bypass
- Priming fluid of bypass machine increases Vd → diluting anesthetic agents
  - INCREASE RECALL RISK

Question 18

Q

What are some considerations when initiating bypass?

Answer

A

Pt placed on bypass, adequate perfusion flow and pressure, pt cooling starts (arterial side)
1. Cease ventilation (dc circuit)
2. IV fluids shut off
3. Volatile anesthetic turned off
4. Make sure perfusionist has instituted anesthetic
5. Pull back Swan catheter – tends to float in further
6. Give NMB to prevent shivering, along with fentanyl/versed

Question 19

Q

What do the clamps create during CPB?

Answer

A

Clamp separates two sections.

Aortic cannulation allows blood to go to systemic circulation
Cardioplegia solution- contains high K+ & cold

Clamp prevents cold/K+ soln going to arterial side since right next to each other

Question 20

Q

Purpose of cardioplegia solution? Contents?

Answer

A

Heart stops

Cold- 4°C
- Reduces metabolism of heart (protection)
- V-fib occurs at 25-30°C
Contains K⁺(high dose)
- Depolarization of heart

Question 21

Q

What happens with the intiation of bypas?

Answer

A

Significant drop in BP

Causes:
- Hemodilution → ↓ viscosity
  - From priming fluids (perfusionist)
- Rapid dilution of catecholamines
- Rapid cooling
  - for brain, heart, liver
- Aortic cross-clamp-to prevent systemic extravasation of antegrade cardioplegic solution

Question 22

Q

What is the pump primed with?

Answer

A

Primed with 2000 cc of crystalloids (rich in…)

Heparin
Mannitol
NaHCO₃^-
Albumin
Corticosteroids
Antifibrinolytics (aminocaproic acid/Amicar) to protect blood vessels

Question 23

Q

What hemodynamic changes occur with the initiation of bypass?

Answer

A

Once the heart has been arrested (heart goes into fibrillation d/t cardioplegia soln)
- Revascularization/valve replacement is instituted
Flow is no longer pulsatile (no BP, just flow from bypass machine)
- only have MAP
Flow rate (BP is one number, reflective of flow)
- Flow rate usually 50-60 ml/kg (bypass lecture 2.4L/min/m2
- BP maintained at 50-60 mmHg
  - Considerations;
    - Lower BP (flow)
      - beneficial for hematology
        (saving blood cells and preventing blood cell breakdown)
      - Possibly issues perfusing brain/kidneys during non-pulsatile flow
    - Higher BP (flow)
      - beneficial for stroke pts/carotid dz (need extra cerebral perfusion) or kidneys
- CVP is 0mmHg
  - if higher → may have kink

Question 24

Q

What are some hematological effects of CPB?

Answer

A

Effects both extrinsic and intrinsic coagulation pathways
- Factor XII conversion to Factor XIIa on various surfaces of CPB circuit
Directly impairs platelet function
- Rapid adhesion and conformational alteration of plasma proteins
  - i.e., von Willebrand factor (vWF) and fibrinogen (Fib)
- Platelet aggregation, and detachment due to shear forces
Monocyte and endothelial activation with TF and tissue/vessel injury
Tissue (vessel) injury → Extrinsic pathway → release of TF → causes both initiation of intrinsic pathway and common pathway
- Intrinsic pathway (via IX)
- Common pathway (via X)
Understand adhesion and damage to cell from pt being on bypass

Question 25

Q

How do we provide prophylaxis for bleeding?

Answer

A

Prophylactic use of antifibrinolytic drugs before CPB
- reduces bleeding and transfusion
Drugs include:
- Synthetic lysine analogues
  - ε-aminocaproic acid (EACA) – Amicar
  - Transexamic acid (TXA)
- Serine protease inhibitor = Aprotinin
  - Taken off the market dt significant tissue organ damage
  - Being researched again in Canada
    - Amicar bolus and infusion PRE pump to reduce bleeding and need for transfusion

Question 26

Q

What are some CNS risks while on pump? People at risk?

Answer

A

Risks:

Embolization
Hypoperfusion
- Bypass machine at low pressures/flow
Inflammation from pulsatile to flow BP

Influencing Factors/predisposition: (people at risk)

Aortic atheromatous plaque (atherosclerosis in aorta)
Cerebrovascular disease
Altered cerebral autoregulation (elderly)
HoTN
Intracardiac debris
- Plagues
Air
Cerebral venous obstruction on bypass
Cardiopulmonary bypass circuit surface and damaged blood cells
Reinfusion of unprocessed shed blood (cell saver)
Cerebral hyperthermia (rewarmed too quickly)
Hypoxia (serial ABGs)

Question 27

Q

How can we provide cerebral protection while on bypass?

Answer

A

Emboli are biggest culprits
PROTECTION:
- Hypothermia → decrease CMRO2
- Barbiturate therapy?
  - Used to give TPL/Methohexital decrease BF to brain
- CCBs
  - increase perfusion to brain
- Blood gas management
  - Draw from aline
- Adequate BP (run machine at good flows)
  - blood cell damage vs. CPP? Individualized
    - (look at risk list above and those prob need higher pressures)
- Cerebral oximetry

Question 28

Q

Fluid managmeent considerations while on bypass?

Answer

A

Minimize crystalloids – hemodilutes pt
- 1-1.5 L acceptable for crystalloids
Replace blood w/:
- Colloids
- Cell saver
- PRBCs

Question 29

Q

Rewarming considerations?

Answer

A

Begins at different times: (Surgeon can ask for rewarming of pt)
- 1. Begins prior to aortic cross-clamp removal (or)
- 2. Begins with the last distal anastomosis in angioplasty procedure (or)
- 3. Begins when all the valve sutures are in and knots are being tied down
Considerations:
- 1° C per 3-5 mins (slowly)
  - Usually takes ~ 30-40 mins
- Turn on heating blanket
- Temp gradient bt arterial and venous blood should remain < 5-10°C
  - if gradient higher → higher risk of air emboli
- Amnestic and NMB agents should be given (recall)
- SVR drops d/t vasodilation
  - Monitor pressure*
  - Phenylephrine can be given to perfusionist since they have more direct access

Question 30

Q

What must occur prior to the discontinuation of bypass?

Answer

A

Pt must be warmed
Surgical field should be _dry (_no bleeding)
Lab values checked
- Admin Ca & Mag to decrease effects of cardioplegic soln (high K)
Pulmonary compliance evaluated
- Begin ventilating lungs slowly (attach circuit)
  - Manually bag pt to see compliance → watch lungs
  - Then switch to ventilator
Regulate cardiac rhythm by pacing, defibrillating or pharmacologically
- Ca, Mg
Transfuse pt with pump volume (~50-100cc by perfusionist)
- Look at:
  - PA Diastolic pressure
  - TEE*
  - Actual heart over drapes (floppy?)
  - VS

Question 31

Q

Pneumonic to help remember preparation to wean from bypass?

Answer

A

“CVP”
- Cells- PRBCs
- Vaporizers- turn on gas since perfusionist turns off theirs
- Volume expanders- for HoTN
- Predictors:
  - Based off preop assessment
    - Arrythmias beforehand?
- Potassium/Mag/Calcium balance
- Protamine- AFTER everything else looks good (last thing)

Question 32

Q

Considerations during discontinuation of bypass?

Answer

A

Use the ratio of systemic BP to pulm BP
EXAMPLES:
- If pulm pressure ↑, but BP ↓ = ventricular failure (inotropic agent)
  - PA pressure high → diastolic fx not working properly and BP low → SV or stroke pressure poor → ventricle not fx properly
    - Tx: Inotropic agent→ increase force of contraction
- If CO is low, but BP is adequate = SVR high (overly vasoconstricted)
  - BP good but heart cant pump against heavy constriction
    - Tx: vasodilation
- If BP is low:
  - Inotropes
  - volume (cell saver, PRBC, whole blood)
Diagnose THEN treat
- Look at BP and PA pressures
Once the pt is stable, bypass is completely d/c’d

Question 33

Q

How do we support ventricular function during bypass weaning?

Answer

A

Assess function

LV support =

Inotropes
PRBC
Preload
afterload

RV support = (need to ↓ pulm vasoconstriction)

Nitric oxide-based vasodilators
β₂ agonists
prostaglandin E₁
- RV failing unrelated to pulm vasoconstriction:
  - cyclic adenosine monophosphate-specific phosphodiesterase inhibitors
    - (Phosphodiesterase inhibitors are a class of medications that promote blood vessel dilation (vasodilation) and smooth muscle relaxation in certain parts of the body, such as the heart, lungs, and genitals)
- If not working:
  - IABP (intra-arterial balloon pump)
  - Ventricular Assist Devices

Question 34

Q

“Steps” for bypass weaning?

Answer

A

Step 1:

HR < 70 (conduction block)

Pace
Atropine
Isopril

HR > 100

Balance Mg/K
Cardiovert
Amiodarone

Preload optimization →

High Preload:

stop filling
head up tilt (reduce blood coming back to heart)
diuretics

MAP > 90

vasodilators (NTG, NPS)

Once all criteria met → then can successfully come off bypass and remove arterial cannula and TE

THEN give protamine. (ACT come back to normal)

Step 2: (if not able to wean)

Ventricular failure
- Tx: inotropes, blood back from pump, inhaled NO, etc
If successful, ok to come off arterial cannula and TEE→ then give protamine and ACT check

If not successful → balloon pump or VAD to leave

Question 35

Q

Parameters used to determine treatment for TEE?

Answer

A

Example:

BP and VFP high
CO low
- Dx: high vasoconstriction (or)
- Low contractility
  - Tx: Inotrope or vasodilation

Example:

BP down
Filling pressures down
SV up
- Dx: DECREASE SVR
- Tx: Vasoconstrictor

Question 36

Q

What is protamine? Dosage?

Answer

A

Derived from salmon sperm
- Pts w/ vasectomies (develop AB against sperm) → Allergic Rx to protamine
Dose:
- 2-4 mg/kg
- 1-1.3 mg per 100units of Heparin given
  - Administration considerations:
    - SLOWLY push (over 5-10 min)
      - *Massive vasodilation/drop in BP*
    - CVP line (draw back and ensure good line)
    - Check ACT and give more accordingly
      - ~ < 100

Question 37

Q

Considerations for anaphylaxis with protamine?

Answer

A

Anaphylaxis can occur: Admin w/ premedication or alternatives to heparin
- Pts with previous exposure
- Pts with vasectomy
- Pts on NPH (Neutral Protamine Hagedorn) (prior exposure technically)
  - Can cause vasodilation, give slowly over >5mins.
Pts with documented adverse events related to protamine → do not rechallenge with protamine
Pharmacologic alternatives to protamine:
- Do not reverse heparin
- Non–heparin-based CPB
- Performing off-pump coronary artery bypass (OPCAB) with an alternative to heparin
  - Surgeon dependent (variable)
Non-protamine heparin reversal drugs: (if heparin used)
- PF4
- Heparinase
  - MOA: deactivates heparin (not technically reversing it)
- Simply waiting for heparin’s effects to dissipate

Question 38

Q

Post bypass and postop considerations after cardiac surgery?

Answer

A

Post Bypass

Transfusion
Coagulation
Stability of VS
Drop in BP with chest closure *
Maintain inotropes, NTG, NTP, etc.
Continue vigilant watch

Post op

Travel to ICU/CCU with monitors & + O₂
Bring backs
- 4-10%
  - usually d/t bleeding → less common now w/ TEE
- Cardiac tamponade
Post op pain control
- Sternotomy very painful!
  - Ex: Fentanyl drip, morphine, dilaudid, etc

Question 39

Q

Considerations around minimally invasive cardiac surgery?

Answer

A

Numerous approaches
Techniques vary amongst sites and surgeons
Good practice:
- ↓ HR and ↑ preload
  - Surgeon handling heart → good way to maintain BP
- Avoid and tx arrhythmias
  - Handing might cause arrythmias
- Adjust ventilator settings
  - Ex: small TV, higher RR, add PEEP
- Heparin available in case pt has to go on bypass
- Reversal of heparin depends on the institution