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Flashcards in Exam 1 Deck (58):
1

Major branches of Left Coronary Artery

LAD (diagonal, septal perforator, intermediate)

Circumflex (OM, PDA in some)

2

Major branches of RCA

SA nodal

AV nodal acute marginal

PDA in most people

3

Most effective monitors used to detect myocardial ischemia

ECG
PAC
TEE
Visual

4

Factors which both decrease myocardial oxygen supply and increase demand

Heart rate

PCWP

5

2 factors affecting coronary perfusion pressure

DBP and PCWP

CPP= DBP - PCWP

6

Role of heart rate management in optimizing myocardial oxygen supply and demand

Total time in diastole decreases as heart rate increases

Total time in diastole is key in perfusion

7

Most important causes of myocardial ischemia

Heart rate

CPP

8

Hemodynamic variable most commonly associated with myocardial ischemia

Heart rate

9

Factors which may adversely affect ventricular wall tension

SBP

Afterload

LV filling volumes

Myocardial ischemia

10

Effect of IABP on myocardial oxygen supply

Augments DBP via coronary and systemic perfusion

Decreases demand, increases supply of oxygen

11

Effect of IABP on myocardial oxygen gemand

Decrease workload

Decrease oxygen consumption

Increases CO

Decreases hemodynamic abnormalities associated with mechanical defects

12

Most commonly associated complication associated with CABG

Afib or rhythm disturbances 22%

MI 5-50%

Bleeding 5%

Death 3-4%

ARF, sternal wound infection 2-5%

Pumphead, pumplung

13

Predictors of M&M with CABG

Age
Prior MI
Location of MI
Coagulopathies
CHF
Dysrhythmia
HTN
DM
CVA
PVD
Valvular disease
Smoking
Lung disease

14

Time period most associated with M&M after an MI

<1 month 35%

<6 months 15%

>6 months 5%

15

2 tests measuring ventricular function in pt presenting for CABG

Echo
LHC

16

Commonly used home meds in patients with CAD presenting for CABG

Beta blockers

Calcium channel blockers/ACE inhibitors

Diuretics/thiazides

17

Indications for placement of PAC

LV dysfunction

Angina w/i 48 hours

Symptomatic valve disease

Severe HTN with angina hx

Large operation- vascular vol changes

Vascular surgery w/ major artery clamp

18

Uses of PAC data during CABG

Measure CO & optimize perfusion

Detect, treat, and trend myocardial ischemia and valve dysfunction

Measure and optimize ventricular preload in sg with lg volume shifts or aortic cross clamp

19

Uses of intraop TEE during CABG

Ventricular function (EF, motion)

Wall motion abnormalities

Valve dysfunction

Stenosis or regurgitation

Chamber side may be indicative of dysrhythmia, dysfunction

20

2 important aspects of pt management during CABG

Avoid hypoxia and hypotension

Support hemodynamics

21

Effect of fentanyl on volatile agent requirements

Higher dose = more reduction in MAC

25 mcg/kg 40%

100mcg/kg 75%

22

Fentanyl and sternotomy

Increase HR, MAP, CI and MVO2

23

Halothane and nitrous during sternotomy

Control HR but decrease MAP, CI, MVO2

24

Dose of epi associated with extrasystoles when using isoflurane

10mcg/kg epi= 100% ventricular exprasystoles

7 mcg/kg = 50%

5mcg/kg = less than 20%

25

Causes of myocardial ischemia during anesthesia

Coronary artery occlusion

Tachycardia

High PCWP/CVP (>12-15)

Hypotension

Severe Hypertension

Increased workload of heart or high CO (sepsis)

26

Signs of myocardial ischemia

ST segment abnormality

Dysrhythmia

Conduction abnormality

PA waveform abnormality

Decreased myocardial performance (low CI or BP)

Wall motion abnormality

27

Nitrates intervention for myocardial ischemia

Greatly decrease LV wall tension and coronary resistance

Slight increase in HR and contractility

No change in aortic pressure

28

Beta blockers as interventions for myocardial ischemia

Greatly decrease contractility and heart rate

Decrease LV wall tension and aortic pressure

No change in coronary resistance

29

Calcium blocking drugs as interventions for myocardial ischemia

Greatly decrease coronary resistance

Decrease LV wall tension and aortic pressure

30

Subgroups of pt requiring higher perfusion pressures (higher MAP)

Acute MI/ongoing ischemia

Renal/cerebral insufficiency

L main/Lmain equivalent

Aortic stenosis

Chronic hypertension

31

4 potential sources of conduit for bypass grafts for CABG

Mammary harvest

Vein graft harvest

Radial vein harvest

Gastric-epiploic harvest

32

Mammary harvest for conduit for CABG

LIMA most common

Prone to spasm (papaverine)

33

Vein graft harvest for conduit for CABG

Saphenous most common (5-10 years)

Hearing 3000 units prior to removal

34

Blood pressure maintenance during aortic cannulation

Maintain SBP <100mmHg

35

Sources of rhythm disturbances associated with surgical manipulation immediately prior to CPB

Atrial cannulation

RFG catheter (retrograde cardioplegia)

Pericardiotomy

Lap under heart to explore distal

Ischemia

Dissection out heart for pericarditis

36

Heparin dose and target ACT for on pump CABG

300 units/kg

ACT >400 seconds after pericardiotomy and prior to aortic cannulation

37

Hemodynamic consequences of “mixing” or “RAPing”

Decreases viscosity and circulating NE levels

Decreased SVR

38

What is “mixing” “RAPing”

Draining venous blood to prime CPB circuit

39

4 goals of priorities of CPB

Oxygenation of blood and removal of CO2 (ventilation)

Circulation of the blood

Systemic cooling and rewarming

Diversion of blood from heart to provide bloodless field

40

Order and cross clamping strategies for anastomoses

Distal done with cross clamp on

Mammary done last

Partial clamp on for proximal

Hear defibrillated 10 min after clamp off if in VF/VT

At risk for ischemia until proximal completed

41

Protamine dose after separation from CPB

10mg test dose after venous circuit of machine empties into reservoir

25 mg every minute

Remove aortic cannulation when 1/2 total dose given

Total dose 250mg

Then return volume from reservoir

42

Potential advantages of off pump CABG over on pump CABG

Less neuro impairment

Transient periods of ischemia instead of global ischemia

Fewer inotrope

Improved hemostasis

Less transfusions and fluid needs

Less postop renal insufficiency

43

Subgroups of pt that may benefit from OPCAB

>70 yrs old

Low EF

Reoperative surgery

Calcified or plaque in aorta

Pt refusing blood products

Significant comorbidities (PAD, CVA, COPD, coagulopathies, renal dysfunction)

44

Role of intracoronary shunts during distal anastamosis

Reduces bleeding

Reduced but maintains blood flow

45

Methods used to displace the heart for distal anastamoses

Octopus stabilization lifts and immobilizes site

Suction cup or starfish lifts apex with suction

Saline/CO2 irrigation to maintain clear surgical field

46

Effect of cardiac displacement on CI, LV/RV filling, myocardial oxygen supply and demand, heart rate

Decreased RV filling but increased pressures (compression)

Decreased RV output = under filled LV = low SV/CO

Hypotension

Valve dysfunction

MI

Dysrhythmia

47

Target vessel positioning most associated with decrease in SV and increased CVP

Vertical position

Distorts MV and TV = significant regurgitation

48

Strategies to manage heart rhythm disturbances during OPCAB

Due to ischemia or mechanical issues

Lidocaine infusion esp for RCA

Mag 2 gm

Maintain K+ >4.0

NTG for distal anastamoses spasm

Pacer always available

49

Heparinization and target ACTS for OPCAB

1.5-2mg/kg

Goal ACT >250 during anastamoses

Usually dose 10,000-15,000 units (1/2 full CPB dose)

ACT q30minutes

50

Best monitors for evaluating cardiac performance and ischemia during cardiac displacement

Arterial line and operative field

51

PAC and TEE use for monitoring cardiac performance and ischemia during cardiac displacement

CI superior to TEE with displacement

TEE useful for RWMA

52

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

Maintain reasonable HR

Levo infusion 2-6mcg/min background

Use gtt instead of bolus

Epi blouses 10-20mcg if CI < 1.5

Volume load immediately prior to verticalization and stabilization

53

Uses and limitations of NTG during OPCAB

Decreases PCWP so optimizes coronary perfusion

Decreases wall tension and MVO2

Decrease MR and PAP

(Decreased preload can be detrimental bc higher filling pressures are needed to ensure optimal ventricular filling)

54

Protamine reversal of heparin with OPCAB

1mg protamine for every 1.3mg heparin

Usually 100mg protamine

55

Grafting order for OPCAB

Collateralized

LAD with LIMA

Proximal before distal

Diagonal

RCA

PDA

Circ, 2nd and 3rd OM

Posterior lateral

Ramus

56

Ventilation and acid base balance during OPCAB

Hand ventilation and low tidal volumes during distal

Treat metabolic acidosis with NaHCO3 to keep pH >7.3

Compliance and FRC reduced

57

Proximal anastamoses during OPCAB BP

Partial cross clamp applied

SBP 100

58

To eligible for extubation in OR pt must

Awake

Normothermia

Non-acidotic

Adequately ventilating