Test 1

Question 1

List the three most effective monitors used to detect myocardial ischemia

Answer 1

• ECG
• PAC
• TEE
• Visual

Question 2

List major branches of the right coronary artery

Answer 2

o SA Nodal
o AV nodal Acute Marginal
o Posterior descending artery

Question 3

List major branches of the left coronary artery

Answer 3

1. Left anterior descending -> diagonal, septal perforator, intermediate
2. Circumflex -> obtuse marginal, posterior descending artery

Question 4

List two factors which both decrease myocardial oxygen supply and increase demand

Answer 4

o Heart rate and PCWP

Question 5

Discuss the role of heart rate management in optimizing myocardial oxygen supply and demand

Answer 5

o Along with CPP, most important cause of myocardial ischemia
o LV fills during diastole
o Total time in diastole key in perfusion
o Modest increase in demand major effect on supply
–> Total time in diastole decreases and heart rate increases

Question 6

Identify the hemodynamic variable most commonly associated with myocardial ischemia

Answer 6

o When heart rate increased to 146 bpm; SBP increased to 196 mmHg
 Angina increases 80% in hr and 30% with SBP
 ST depression increase 70% with hr and 20% with SBP
 In Anesthesia if hr <70- less than 30% have ischemia, if hr > or = 110- about 65% may experience ischemia

Question 7

List four factors which may adversely affect ventricular wall tension

Answer 7

(CPP = DBP -LVEDP) 
o	Systolic BP
o	Afterload
o	LV filling volumes
o	Myocardial ischemia

Question 8

Identify the effect of intra-Aortic balloon pump on myocardial oxygen supply

Answer 8

o During diastole, the balloon inflates and augments the diastolic pressures via coronary and systemic perfusion

Question 9

Identify the effect of the intra-aortic balloon pump on myocardial oxygen demand

Answer 9

o During systole, the balloon deflates and it reduces afterload
 DECREASE cardiac workload
 Decrease myocardial oxygen consumption
 Increase cardiac output
 Decrease hemodynamic abnormalities associated with mechanical defects

Question 10

Identify the most commonly associated complication associated with CABG

Answer 10

1. Afib or other rhythm disturbances: 22%
2. MI: 5-10%
3. Post op bleeding: 5%
4. Death: 3-4%
5. Acute renal failure: 2-5%
6. Sternal wound infection: 2-5%
7. Stroke: 1-2%
8. Post-perfusion syndrome: “pumphead”
9. Respiratory failure: “pump lung”

Question 11

List four predictors of morbidity/mortality with CABG

Answer 11

o	Age
o	Previous MI
o	Location of MI
o	Coagulopathy 
o	CHF/Heart failure
o	Dysrhythmias
o	HTN
o	DM
o	Cerebrovascular disease
o	PVD
o	Valvular heart disease
o	Cigarette smoking
o	Lung disease 
o	ECG abnormalities

Question 12

Identify which time period is most associated with morbidity/mortality after an MI

Answer 12

o <1 mo: 35%
o <6 mo: 15%
o >6 mo: 5%

Question 13

List two tests measuring ventricular function in the patient presenting for CABG

Answer 13

o Cath, echo

Question 14

List three commonly used home medications in patients with CAD presenting for CABG

Answer 14

o Beta blockers -> bradycardia, withdrawal HTN/tachy, last dose
o Calcium blockers/Ace Inhibitors -> hypotension, orthostasis
o Diuretics/Thiazides-> hypovolemia, orthostasis, hypokalemia
o Hospital meds -> Heparin, nitrates, insulin

Question 15

List three indications for placement of a pulmonary artery catheter

Answer 15

o LV dysfunction
o Angina within the last 48 hours
o Symptomatic valvular disease
o Severe hypertensive with angina history
o Large operation with anticipation of intravascular volume changes
o Vascular surgery with clamp of major artery

Question 16

Describe four uses of pulmonary artery catheter data during CABG

Answer 16

o Measure CO and optimize perfusion
o Detect, treat and trend myocardial ischemia
o Measure and optimize ventricular preload and volume in surgery with large volume shifts
o Measure and optimize ventricular preload and volume in surgery during aortic cross clamp
o Detect, treat and trend valve dysfunction

Question 17

Describe three clinical uses of intraoperative TEE during CABG

Answer 17

o	Ventricular function (EF, wall motion)
o	Wall motion abnormalities 
o	Valve dysfunction 
o	Stenosis or regurgitation 
o	Chamber size may be indicative of dysrhythmias, dysfunction

Question 18

Calculate drug doses for induction using commonly used anesthetic agents
(Phenylephrine)

Answer 18

30-60 mcg/min vs. bolus



Question 19

Calculate drug doses for induction using commonly used anesthetic agents (Midazolam)

Answer 19

3-5 mg

Question 20

Calculate drug doses for induction using commonly used anesthetic agents (Propofol)

Answer 20

20-100 mg

Question 21

 Calculate drug doses for induction using commonly used anesthetic agents (Etomidate )

Answer 21

 10-20 mg

Question 22

 Calculate drug doses for induction using commonly used anesthetic agents (Fentanyl )

Answer 22

3-25 mcg/kg

Question 23

 Calculate drug doses for induction using commonly used anesthetic agents (Sufentanil )

Answer 23

0.5-1.5 mcg/kg

Question 24

4. Muscle Relaxants ( Three)

Answer 24

 Vecuronium, Rocuronium, Succinylcholine

Question 25

Describe the effect of fentanyl on volatile agent requirements

Answer 25

o Fentanyl25mcg/kg: 40% reduction on MAC o 50 mcg/kg: 55% reduction on MAC o 75 mcg/kg: 65% reduction on MAC o 100 mcg/kg: 75% reduction on MAC o Fentanyl increases HR, MAP CI, and MVO2 upon sternotomy o Halothane and Nitrous control HR but decrease MAP, CI, and MVO2 during sternotomy

Question 26

Identify the dose of epinephrine associated with extrasystoles when using isoflurane

Answer 26

o 10 mcg/kg of epinephrine = 100% of patients exhibit ventricular extrasystole o 7 mcg/kg = 50% of patients exhibiting ventricular extrasystole o At 5 mcg/kg = less than 20% exhibit ventricular extra systole

Question 27

List three causes of myocardial ischemia During Anesthesia

Answer 27

``` o Coronary artery occlusion o Tachycardia (>100/min) o High PCWP/CVP (>12-15) o Hypotension o Severe hypertension o Increased workload of heart or high cardiac output (sepsis ```

Question 28

List three signs of myocardial ischemia

Answer 28

``` o St segment abnormality o Dysrhythmias o Conduction abnormality o PA waveform abnormality o Decreased myocardial performance (low CI or BP) o Wall motion abnormality (echo, visual) ```

Question 29

Identify four subgroups of patients requiring higher perfusion pressures (higher MAP)

Answer 29

``` o Acute MI/Ongoing Ischemia o Renal/Cerebral Insufficiency o Left Main/Left Main Equivalent o Aortic Stenosis o Chronic Hypertension ```

Question 30

List four potential sources of conduit for bypass grafts for CABG

Answer 30

1. Mammary Harvest  LIMA: almost always harvested as a graft unless subclavian stenosis or emergency  RIMa: rarely harvested due to distance to heart from right sternum but may be used as “free graft”  IMA: may need to hand ventilate during harvest -> prone to spasm, surgeon will check flow after harvest and attach bulldog +/- papaverine for spasms **Heparin may be given in varying mounts if mammary opened and flow checked 2. Vein Graft Harvest  SVG 30” to 5=10 years  Can be endoscopic vs. open harvest  Heparin 3000 units administered prior to taking vein from leg  Greater saphenous usually taken but if previous CABG or bad vein may go prone for lesser saphenous 3. Radial vein harvest 4. Gastric-epiploic harvest

Question 31

Discuss blood pressure maintenance during aortic cannulation

Answer 31

o Aortic cannulation sutures with tourniquet will be placed in ascending aorta (MAINTAIN SBP <100 mmHg, communication with surgeon)

Question 32

List four sources of rhythm disturbances associated with surgical manipulation immediately prior to cardiopulmonary bypass

Answer 32

o Atrial cannulation/vent stitch (death grip, etc.) o RFG catheter (retrograde cardioplegia) o Pericardiotomy o Lap under heart to explorer distal o Myocardial ischemia o Dissecting out heart for red/pericarditis

Question 33

Discuss heparin dose and target ACTs for on-bypass CABG

Answer 33

o Heparin 300 units/kg at some point | o ACT > 400 seconds at some point after pericardiotomy and prior to aortic cannulation

Question 34

Describe the hemodynamic consequences of “mixing” or “RAPing”

Answer 34

o “Mix/Rap”  Retrograde autologous priming  Drains venous blood from patient to prime CPB circuit  Decreases viscosity and circulating norepinephrine levels (decreases SVR) o Mugging/Leeching by surgeon dealt with by transfusion back from CPB, alpha drug, and communication

Question 35

List four goals or priorities of cardiopulmonary bypass

Answer 35

o Oxygenation of blood and elimination of carbon dioxide (ventilation o Circulation of the blood o Systemic cooling and rewarding o Diversion of blood from the heart to provide a bloodless surgical field (aortic crossclamp, cardioplegia

Question 36

Compare cross-clamp strategies for distal anastomoses and proximal anastomoses

Answer 36

o Distals usually done with cross clamp on o Mammary usually done last (to avoid twisting IMA) o Reward initiated after last distal o Cross-clamp removed, partial clamp of aorta for proximals o Heart defibrillated 10” after clamp off if in VF/VT o At risk for ischemia until proximals competed

Question 37

Discuss protamine dosing after separation from CPB

Answer 37

o Remove venous cannulation and drain venous circuit of heart-lung machine into reservoir (extra volume) o When satisfied with heart performance start protamine after 10 mg test dose o Give 25 mg Protamine every minute o Typical protamine dose is 250 mg o Administer volume from pump to compensate for arterial and venous dilation o Remove aortic cannula when ½ of the protamine dose is in

Question 38

Compare OPCAB to conventional CABG in regards to construction of distal anastomoses

Answer 38

1. OPCAB  Beating heart, absence of CPB  Use of an epicardial stabilizer and displaced heart  Temporary interruption of coronary blood flow during anastomoses and regional ischemia  Bypass of 1-7 vessels  Extubation either on table or very shortly thereafter  Timing of hemodynamic manipulation is optimized by knowing order of grafts, when displacement is to occur  After displacement, silastic tape is placed around vessel to produce proximal coronary occlusion and lift vessel into better place  If tolerate, the epicardial stabilizing device is placed  Stabilization of the target site is accomplished by using one of the many stabilizer, which work by compression and lifting  These stabilizers create an immobile field, but if used as retractors the heart will slip and compression will cause hemodynamic compromise

Question 39

List four potential advantages of OPCAB over conventional CABG

Answer 39

o Less neuropsychological impairment (short-term only, ? Same at 12 months) o Transient periods of regional myocaridal ischemia instead of global myocardial ischemia o Fewer inotropes, fewer dysrhythmias postop o Improved hemostasis o Less need fro transfusion and fluids o Less postoperative renal insufficiency

Question 40

List from subgroups of patients that may benefit from OPCAB

Answer 40

``` o Age > 70 years o Low EF o Reoperative surgery o Patients with significant comorbidities: cerebrovascular disease, peripheral vascular disease, bleeding disorders, COPD, renal dysfunction o Atheromatous or calcified aorta o Patients who refuse blood products ```

Question 41

Describe the role of intracoronary shunts in performing distal anastomoses

Answer 41

o A double limb shunt (proximal and distal ends) is placed after arteriotomy o Bleeding from arteriotomy site during anastomoses is reduced o Coronary blood flow is maintained through reduced o Blood loss results regardless

Question 42

Describe methods used to displace the heart for distal anastomoses

Answer 42

o Octopus stabilization system lifts and immobilizes the anastomotic site o Suction cup or starfish is use that lifts the apex by applying suction o Saline/carbon dioxide irrigation system is used to maintain clear surgical

Question 43

Describe the effect of cardiac displacement on CI, left/right ventricular filling, myocardial oxygen supply and demand and heart rhythm

Answer 43

o Thin right atrium is compressed by positioning, resulting in decreased RV filling but elevated filling pressures o Decreased RV output results in an under-filled left ventricle and low stroke volume/cardiac output o Decreased CO results in decreased BP ``` o Marked decrease in cardiac output and SV o Profound hypotension o Increased filling pressures o Valve dysfunction o MI o Dysrythmias ```

Question 44

Identify the target vessel positioning most associated with decrease in SV and increase in CVP

Answer 44

o The vertical position of the heart produces distortion of the mitral and tricuspid annuli and significant regurgitation may occur o Large “v” waves on the pulmonary artery tracing without LV failure are diagnostic o Abnormal valves become more distorted by positioning

Question 45

List four strageties used to manage heart rhythm disturbances during OPCAB

Answer 45

o Rhythm disturbances from ischemia or mechanical issues o Consider lidocaine infusion, especially for RCA o Mag 2 grams, maintain K at 4.0 o NTG often administered during distal anastomoses for spasm o Pacemaker always ready available due to need for higher HR

Question 46

Discuss heparinization and target ACTs for OPCAB

Answer 46

o Heparin dose should be 1.5-2 mg/kg, aiming to keep the ACT > 250 seconds during vessels anastomoses o Dose usually 10,000-15,000 units (1/2 full CPB dose) o Heparin 3000 units if vein taken prior to bolus for revascularization o ACT should be repeated every 30 min

Question 47

Compare PAC use to TEE for monitoring of cardiac performance and ischemia during cardiac displacement

Answer 47

o ECG position dependent o PCWP affected by displacement and ischemic o Arterial line, operative field are best monitors o CI superior to TEE with displacement o TEE is useful for RWMA

Question 48

List four surgical maneuvers which may limit hemodynamic compromise during cardiac displacement

Answer 48

o Order of grafts based on hemodynamic consequences (LAD-PDA-Circ) o OR graft most diseased vessel first o Close communication with anesthesia with modification of position as needed o DPS to bring great vessels and chambers into same plane o Open right pleura for lateral walls grafts to allow heart to rotate and avoid compression o Open right pericardium to allow heart to drop into right chest cavity o Lift right sternum to make more space for the heart (towel under right side of sternal retractor) o Remove pleurocardial fat pad to make more room for heart o Suture musculofascial tissue on the posterior part of mediastinum to allow heart to drop posteriorly o Moderate right lateral decubitis positioning at 30-45 degrees to allow gravity-assisted rotation of the heart rightward and preserve hemodynamics

Question 49

Describe management of heart rate, vascular tone and LV filling immediately prior to cardiac displacement

Answer 49

o Maintenance of reasonable heart rate o Background infusion of norepinephrine (2-6 mcg/min) may be utilized to maintain BP and CO o Infusion should be utilized instead of bolus, port closest to circulation o Volume loading (500 ml Albumin vs 2000 ml crystalloids) immediately prior to verticalization and stabilization o If CI remains less than 1.5, bolus doses of epi (10-20 mcg) are administered o Proactive treatment of ischemia-induced ventricular function is essential o Right ventricular compression especially with verticalization requires increase preload to maintain left ventricular filling o Anticipation of distals and effect on BP/CI essential, hespan/trendelenberg key

Question 50

Describes uses and limitations of NTG during OPCAB

Answer 50

o Useful in optimizing coronary perfusion pressure by decreasing PCWP o Decreases wall tension and MVO2 o Decrease mitral regurgitation and pulmonary artery pressures o Double edge sword as decrease in preload can be detrimental, as higher filling pressures are needed to ensure optimal ventricular filling

Question 51

Compare protamine reversal of heparin with OPCAB

Answer 51

o Reversal dose is 1 mg protamine for every 1/3 mg active heparin (usually 100 mg protamine, dose variable sometimes only 50 mg)