Test 1 Flashcards
List the three most effective monitors used to detect myocardial ischemia
- ECG
- PAC
- TEE
- Visual
List major branches of the right coronary artery
o SA Nodal
o AV nodal Acute Marginal
o Posterior descending artery
List major branches of the left coronary artery
- Left anterior descending -> diagonal, septal perforator, intermediate
- Circumflex -> obtuse marginal, posterior descending artery
List two factors which both decrease myocardial oxygen supply and increase demand
o Heart rate and PCWP
Discuss the role of heart rate management in optimizing myocardial oxygen supply and demand
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
Identify the hemodynamic variable most commonly associated with myocardial ischemia
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
List four factors which may adversely affect ventricular wall tension
(CPP = DBP -LVEDP) o Systolic BP o Afterload o LV filling volumes o Myocardial ischemia
Identify the effect of intra-Aortic balloon pump on myocardial oxygen supply
o During diastole, the balloon inflates and augments the diastolic pressures via coronary and systemic perfusion
Identify the effect of the intra-aortic balloon pump on myocardial oxygen demand
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
Identify the most commonly associated complication associated with CABG
- Afib or other rhythm disturbances: 22%
- MI: 5-10%
- Post op bleeding: 5%
- Death: 3-4%
- Acute renal failure: 2-5%
- Sternal wound infection: 2-5%
- Stroke: 1-2%
- Post-perfusion syndrome: “pumphead”
- Respiratory failure: “pump lung”
List four predictors of morbidity/mortality with CABG
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
Identify which time period is most associated with morbidity/mortality after an MI
o <1 mo: 35%
o <6 mo: 15%
o >6 mo: 5%
List two tests measuring ventricular function in the patient presenting for CABG
o Cath, echo
List three commonly used home medications in patients with CAD presenting for CABG
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
List three indications for placement of a pulmonary artery catheter
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
Describe four uses of pulmonary artery catheter data during CABG
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
Describe three clinical uses of intraoperative TEE during CABG
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
Calculate drug doses for induction using commonly used anesthetic agents
(Phenylephrine)
30-60 mcg/min vs. bolus
Calculate drug doses for induction using commonly used anesthetic agents (Midazolam)
3-5 mg
Calculate drug doses for induction using commonly used anesthetic agents (Propofol)
20-100 mg
Calculate drug doses for induction using commonly used anesthetic agents (Etomidate )
10-20 mg
Calculate drug doses for induction using commonly used anesthetic agents (Fentanyl )
3-25 mcg/kg
Calculate drug doses for induction using commonly used anesthetic agents (Sufentanil )
0.5-1.5 mcg/kg
- Muscle Relaxants ( Three)
Vecuronium, Rocuronium, Succinylcholine
Describe the effect of fentanyl on volatile agent requirements
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
Identify the dose of epinephrine associated with extrasystoles when using isoflurane
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
List three causes of myocardial ischemia During Anesthesia
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
List three signs of myocardial ischemia
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)
Identify four subgroups of patients requiring higher perfusion pressures (higher MAP)
o Acute MI/Ongoing Ischemia o Renal/Cerebral Insufficiency o Left Main/Left Main Equivalent o Aortic Stenosis o Chronic Hypertension
List four potential sources of conduit for bypass grafts for CABG
- 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 - 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 - Radial vein harvest
- Gastric-epiploic harvest
Discuss blood pressure maintenance during aortic cannulation
o Aortic cannulation sutures with tourniquet will be placed in ascending aorta (MAINTAIN SBP <100 mmHg, communication with surgeon)
List four sources of rhythm disturbances associated with surgical manipulation immediately prior to cardiopulmonary bypass
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
Discuss heparin dose and target ACTs for on-bypass CABG
o Heparin 300 units/kg at some point
o ACT > 400 seconds at some point after pericardiotomy and prior to aortic cannulation
Describe the hemodynamic consequences of “mixing” or “RAPing”
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
List four goals or priorities of cardiopulmonary bypass
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
Compare cross-clamp strategies for distal anastomoses and proximal anastomoses
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
Discuss protamine dosing after separation from CPB
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
Compare OPCAB to conventional CABG in regards to construction of distal anastomoses
- 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
List four potential advantages of OPCAB over conventional CABG
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
List from subgroups of patients that may benefit from OPCAB
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
Describe the role of intracoronary shunts in performing distal anastomoses
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
Describe methods used to displace the heart for distal anastomoses
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
Describe the effect of cardiac displacement on CI, left/right ventricular filling, myocardial oxygen supply and demand and heart rhythm
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
Identify the target vessel positioning most associated with decrease in SV and increase in CVP
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
List four strageties used to manage heart rhythm disturbances during OPCAB
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
Discuss heparinization and target ACTs for OPCAB
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
Compare PAC use to TEE for monitoring of cardiac performance and ischemia during cardiac displacement
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
List four surgical maneuvers which may limit hemodynamic compromise during cardiac displacement
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
Describe management of heart rate, vascular tone and LV filling immediately prior to cardiac displacement
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
Describes uses and limitations of NTG during OPCAB
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
Compare protamine reversal of heparin with OPCAB
o Reversal dose is 1 mg protamine for every 1/3 mg active heparin (usually 100 mg protamine, dose variable sometimes only 50 mg)
