AP 3 Test 1 Flashcards
1
Q
Mechanism by which volatile anesthetics depress cardiac contractility
A
Decreases the entry of Ca2+ into cardiac muscle cells during depolarization
2
Q
Mechanism by which nitrous oxide depresses cardiac contractility
A
Dose dependent reduction in availability of intracellular Ca2+ available during contraction
3
Q
Mechanism by which local anesthetics depress cardiac contractility
A
Dose dependent reduction in Ca2+ influx and release
4
Q
Why does acidosis depress cardiac contractility
A
Blocks slow calcium channels
5
Q
Mechanism by which phosphodiesterase inhibitors increase cardiac contractility
A
Prevent breakdown of cAMP which allows for recruitment of open Ca2+ channels
6
Q
Mechanism by which Digitalis increases cardiac contractility
A
Increases intracellular Ca2+ concentration
7
Q
How do hypocalcemia, beta blockers, and calcium channel blockers affect the effects of anesthesia on cardiac function
A
They all potentiate anesthetic-induced cardiac depression
8
Q
Major cardiovascular control center that is the primary regulator of heart rate and BP
A
Medulla
9
Q
Region of the brain that regulates cardiovascular response to changes in temperature
A
Hypothalamus
10
Q
Region of the brain that adjusts cardiac reaction to a variety of emotional states
A
Cerebral cortex
11
Q
Parasympathetic fibers primarily innervate what region of the heart
A
Atria
12
Q
Acetylcholine acts on which receptors in the heart to produce negative effects
A
M2 - negative chronotropy, inotropy, dromotropy (conduction velocity of AV node)
13
Q
What region of the spinal cord contains the cardiac sympathetic fibers
A
T1-T4
14
Q
What is the primary neurotransmitter/receptor pair that has positive chronotropic, dromotropic, and inotropic effects on the heart
A
Norepinephrine acting on beta 1 receptors (sympathetic NS)
15
Q
Location of B2 receptors in the heart
A
Primarily in atria
16
Q
Effect of activating B2 receptors in the heart
A
Increase HR, lesser increase in contractility
17
Q
What causes the increase in heart rate due to inspiration
A
The vagal fibers in the lungs get stretched and activated - this stretch sends an inhibitory signal to the cardioinhibitory center in the medulla and allows for an unopposed sympathetic increase in HR
18
Q
Receptors that mediate baroreceptor reflex
A
Pressoreceptors in the aortic arch and carotid arteries
19
Q
Afferent nerves of baroreceptor reflex
A
- Hering
- Vagus
20
Q
Most important determinant of myocardial blood flow
A
Myocardial oxygen demand
21
Q
Percentage of oxygen requirements dedicated to pressure work
A
64%
22
Q
The myocardium usually extracts __% of oxygen in arterial blood
A
65
23
Q
Most other body tissues other than the myocardium extract __% of oxygen in arterial blood
A
25
24
Q
Why does a fast heart rate cause a decrease in coronary filling?
A
It decreases the time in diastole, which is when coronary filling occurs
25
How does low aortic diastolic pressure affect coronary filling pressure
Decrease
26
How does increased LVEDP affect coronary filling pressure
Decrease
27
Equation for Coronary Perfusion Pressure
Arterial diastolic pressure-LVEDP
28
Main factor that affects CaO2
Hemoglobin concentration
29
Why does aortic stenosis and regurgitation decrease CaO2
They both worsen the blood flow into the coronary arteries
30
What are common causes of decreased coronary vessel diameter and thus decreased oxygen uptake
- Blockage
- Artherosclerotic plaque
- Coronary vasospasm
31
What factors contribute to increased wall tension thus increased oxygen demand
- Increased preload
- Increased BP
- Increased afterload
32
Cardiac index calculation
CI=CO/BSA
33
Normal range for cardiac index
2.5-4.2 L/min/m^2
34
Normal mixed venous oxygen saturation
65-73%
35
Byproduct of anaerobic metabolism used to indirectly assess cardiac output
Lactic acid
36
In the absence of hypoxia or severe anemia, what measurement is the best determination of the adequacy of cardiac output
Mixed venous oxygen saturation
37
What law states the physical relationship between wall tension and internal pressure within a circular structure
Law of LaPlace
38
What is the Frank-Starling Law
The greater the end diastolic volume, the greater the force of muscular contractions thus increasing stroke volume
39
Physiology behind Frank-Starling Law
When there is an increased end diastolic volume, there is increased stretch in the heart wall which increases the affinity of troponin C for calcium - this causes a greater number of cross-bridges to form within the muscle fibers thus increasing contractile force
40
3 primary factors that regulate stroke volume
1) Preload
2) Afterload
3) Contractility
41
Another term for end-diastolic volume
Preload
42
What is preload dependent on
Ventricular filling
43
3 factors that influence preload
1) Venous return
2) Heart rate
3) Heart rhythm
44
Ventricular filling progressively becomes impaired at a heart rate above...
120bpm in adults
45
Atrial arrhythmias can reduce ventricular filling by what percentage?
20-30%
46
Atrial arrhythmia that causes an absent atrial kick
A-fib
47
Atrial arrhythmia that causes an ineffective atrial kick
A-flutter
48
Atrial arrhythmia that causes loss of atrial kick due to altered timing of atrial contraction
Junctional rhythm
49
What measurement is useful to monitor TRENDS in preload and volume
CVP
50
Normal range for CVP
2-8mmHg
51
End diastolic pressure in the right atrium is nearly equal to what other measurement
CVP
52
What fraction of estimated blood volume is in the venous system
2/3
53
How does gravity affect CVP
It redistributes ~500cc of blood from the intrathoracic vessels into the veins of the lower limbs, which reduces CVP and stroke volume
54
How does venoconstriction in response to exercise, shock or hemorrhage affect CVP
Increase
55
Under normal conditions, pulmonary capillary wedge pressure is indicative of what other pressure
Left atrial pressure
56
Assuming normal left ventricular compliance, left ventricular end diastolic pressure is equal to what
Left ventricular end diastolic volume
57
Under what condition can LVEDP be used as a measure of preload
Only if the relationship between ventricular volume and pressure (i.e. ventricular compliance) is constant
58
Left ventricular conditions that cause abnormal compliance during early diastole
- Hypertrophy
- Ischemia
- Asynchrony
59
Left ventricular conditions that cause abnormal compliance during late diastole
Fibrosis
60
SVR calculation
80 x [(MAP-CVP)/CO]
61
Normal range for SVR
900-1500 dyne x s/cm^5
62
PVR calculation
80 x [(PAP-LAP)/CO]
63
Normal range for PVR
50-150 dyne x s/cm^5
64
What branch of the nervous system has the most important effect on cardiac contractility
Sympathetic nervous system
65
Most common physiologic states that depress myocardial contractility
1) Anoxia - lack of O2
2) Acidosis - increased H+
3) Low catecholamine stores
4) Loss of functioning muscle mass - due to ischemia or infarction
66
Influence of parasympathetic system on cardiac function
Negative chronotropy (decrease HR)
67
Influences of sympathetic system on cardiac function
- Positive chronotropy
| - Positive inotropy
68
Influence of high arterial pressure on cardiac output
Lowers cardiac output bc it lowers stroke volume
69
Influence of high preload (filling pressure) on cardiac output
Increases cardiac output bc it increases stroke volume via Starling's Law mechanism
70
Why does stenosis of AV valves reduce stroke volume
Because ventricular preload/filling is decreased due to the stenotic valves
71
Why does stenosis of semilunar valves reduce stroke volume
Because ventricular afterload is increased
72
Define angina
Myocardial ischemia which usually manifests as chest pain
73
Most common cause of angina
Coronary Artery Disease
74
Causes of angina
- CAD
- Vasospasm
- Low cardiac output states (anemia, hypotensive, heart failure)
75
Cardiovascular states that increase oxygen demand
1) Tachycardia
2) HTN aka high afterload
3) Increased contractility
76
Cardiovascular states that decrease oxygen supply
1) Anemia
2) Hypoxemia
3) CAD
4) Vasospasm
5) Hypotension
77
What is stable angina
Angina that occurs with exertion because the diseased coronary artery is maximally vasodilated
78
Treatments for stable angina
Rest or vasodilators
79
What is unstable angina
Angina that has increased in frequency, severity, or duration or occurs at rest
80
Which type of angina is considered an acute coronary syndrome?
Unstable angina
81
What is CAD
Atherosclerotic plaque build up in coronary arteries, limiting blood flow to myocardium
82
What is the leading cause of death in the US
CAD
83
Risk factors for CAD
1) Male
2) Hypertension
3) Hypercholesterolemia
4) Diabetes
5) Obesity
6) Family history
7) Tobacco use
84
Treatment options for CAD
- Lifestyle changes i.e. diet
- Medical therapy
- PCI
- CABG
85
Medical therapies available for CAD treatment
- Beta blockers
- Ca2+ channel blockers
- Nitrates
- ACE inhibitors
- ASA/anti-platelets
- Statins
86
How do we assess functional status and physical exams to ensure a patient with CAD is optimized for surgery?
Assess METs
87
What pertinent information should be pulled from history and records of a patient with CAD to ensure they are optimized for surgery
1) Recent PCI/stent placement
2) Dual anti-platelet therapy
3) Prior revascularization
4) Significant comorbidities (HTN, DM, CKD, PAD, hyperlipidemia)
88
A patient with a previous bare metal stent placement is required to be on dual anti-platelet therapy (aspirin + plavix) for how long after placement?
4-6 weeks
89
A patient with a previous drug alluding stent placement is required to be on dual anti-platelet therapy (aspirin + plavix) for how long after placement?
12 months
90
What is the goal for anesthetic management of a patient with CAD?
Maximize favorable oxygen supply and demand relationship
91
How will cardiac enzyme levels be affected if a patient has a myocardial infarction?
The injured myocardium will release enzymes (i.e. troponin) into the bloodstream so these levels will be elevated after an MI
92
What comorbidity alters the clearance of cardiac enzymes, thus can falsely indicate an MI?
ESRD
93
Which type of MI is marked by ST elevation?
Transmural MI - affects the epicardium, myocardium, and endocardium
94
A transmural MI is usually secondary to what occurrence?
An obstruction in a major coronary artery
95
Which type of MI is marked by ST depression?
Subendocardial MI
96
What test is used perioperatively to assess for wall motion abnormality?
TEE
97
What is the basic definition of heart failure?
Inability of the heart to provide adequate cardiac output to maintain the needs of the body
98
Normal values for cardiac index
2-2.5
99
Most frequent etiology of heart failure
Ischemic (prior MIs, prior CABG, etc)
100
What valvular heart disorders most often cause heart failure?
- Aortic and mitral regurgitation
| - Aortic and mitral stenosis
101
Which etiology of heart failure are patients normally born with?
Non-compaction
102
Which type of heart failure is most common - systolic or diastolic?
Systolic
103
A patient is considered as having a severely low ejection fraction if it is below --%
25
104
Patients with what comorbidity most commonly have diastolic heart failure?
Hypertensive patients due to the impaired relaxation leading to impaired filling
105
Class I Heart Failure
Symptoms of heart failure only at activity levels that would limit normal individuals
106
Class II Heart Failure
Symptoms with ordinary exertion
107
Class III Heart Failure
Symptoms with less than ordinary exertion
108
Class IV Heart Failure
Symptoms at rest
109
Are most LVADs currently implanted pulsatile or continuous flow?
Continuous flow
110
Should inotrope dependent patients with heart failure continue or discontinue these meds perioperatively?
Continue
111
Heart failure patients that are on maximal pharmacologic therapy and still need extra assistance often have what device implanted?
Intra-aortic balloon pump (IABP)
112
How can you monitor BP in a patient with an LVAD?
A-line
113
What are the 2 major functions of an IABP?
- Increase perfusion pressure thus coronary blood flow
| - Decrease afterload
114
IABPs are "counterpulsatile" - what does this mean?
They deflate in systole and inflate in diastole to augment diastole and force blood into the coronary arteries
115
Patients with complete heart block, AV block, or symptomatic bradycardia most likely have which cardiac device?
Pacemaker
116
Category in position I of pacemaker description
Chambers PACED
117
Category in position II of pacemaker description
Chambers SENSED
118
Category in position III of pacemaker description
Response to sensing
119
Category in position IV of pacemaker description
Rate modulation
120
A patient with which type of pacemaker is completely pacemaker dependent?
DOO
121
An automatic implantable cardioverter defibrillator (AICD) has what capabilities?
- Pacing
- Anti-tachycardia pacing
- Defibrillating
122
For which patients is an AICD indicated?
Patients with certain cardiomyopathies, low EF, history of malignant arrhythmia
123
Cardiac resynchronization therapy-dual chamber (CRT-D) is indicated for which patients?
Patients with a significant conduction delay and ineffective systole due to one or both ventricles pumping out of sync with the rest of the heart
124
If a patient has an AAIR pacemaker, what setting might we want to discontinue during surgery?
Rate modulation
125
Monopolar electrocautery during surgery can lead to what phenomena in a patient with a pacemaker
Oversensing - the pacemaker will sense the electrocautery as a native rhythm so it won't pace the patient's heart when it actually needs it
126
What is the most common class of medications that patients with cardiac issues are on?
Beta blockers
127
Cardiac effects from calcium channel blockers
- Decreases SVR
| - Vasodilation
128
Calcium channel blockers can cause what reflex?
Reflex tachycardia - not good for patients with compromised oxygen flow
129
An ultra-short acting IV calcium channel blocker that acts to decrease SVR
Clevidipine
130
Calcium channel blocker used in patients with subarachnoid hemorrhage to prevent cerebral vasospasm
Nimodipine
131
Cardiac effects of nitrates
Causes smooth muscle relaxation which decreases preload and afterload and dilates coronary arteries
132
What is the caution for extended use of nitrates
Tachyphylaxis
133
Cardiac effects of ACE inhibitors
Decreases afterload
134
Contraindications to ACE inhibitors
Angioedema
135
MOA of aspirin (ASA)
Inhibits thromboxane and exerts an anti-platelet effect
136
How soon before surgery should Plavix (clopidogrel) be discontinued?
7 days
137
MOA of Statins
Inhibits HMG-CoA reductase and blocks production of cholesterol in the liver
138
Risk of statins
Myalgias
139
Pacemakers can be classified based on...
location of the leads
140
Where are the leads in a dual chamber pacemaker
Right atrium and right ventricle
141
Where are the leads in a biventricular or CRT pacemaker
Right and left ventricle (and right atrium)
142
Most pacemaker leads are placed __________. What are the other alternatives to this?
Most are placed transvenously. They can also be placed epicardial, transcutaneous, or transesophageal
143
Indications for permanent pacemaker therapy (5)
1) Symptomatic disease of SA node
2) Symptomatic disease of AV node
3) Long QT syndrome
4) Hypertrophic obstructive cardiomyopathy
5) Dilated cardiomyopathy
144
Temporary pacemakers are often placed for...(2)
1) Hemodynamic instability from electrophysiologic source
| 2) Post cardiac surgery
145
Most commonly encountered pacemaker mode
DDD (dual pacing, dual sensing, dual response to sensed beat)
146
What is a "dual" response to a sensed beat?
The pacemaker will be inhibited (I) when a native beat is sensed, and will trigger (T) a beat when needed
147
If a pacemaker is asynchronously pacing, what mode is it in?
DOO (dual pacing of atria and ventricle, no sensing)
148
What pacemaker mode is often used during electrocautery to prevent the bovie from causing asystole?
DOO
149
What is the main reason we should use caution when a patient has a pacemaker in DOO mode?
They are at risk for R on T phenomena which can lead to v-tach or Torsades
150
What is "pacemaker threshold"
The ability of the myocardium to respond to the pacemaker
151
What factors raise pacemaker threshold and make it more difficult to pace?
- Hypokalemia
- Hypocarbia
- Hypoxia
- Hyperglycemia
- Beta blockers
- Rest/sleep
152
What factors lower pacemaker threshold and make it easier to pace?
- Hyperkalemia
- Hypercarbia
- Hyperoxia
- Stress (increased levels of catecholamines)
153
What leads are involved in a biventricular pacemaker?
Right atria, right ventricle, left ventricle
154
What is another name for a biventricular pacemaker
Cardiac resynchronization therapy (CRT)
155
What is the benefit of CRT
Allows for the pacing of both ventricles simultaneously to improve cardiac output
156
What is often seen on an EKG of a patient with a biventricular pacemaker
2 spikes immediately preceding QRS complex
157
What is CRT-P
CRT with only pacing capabilities
158
What is CRT-D
CRT with defibrillation capabilities
159
Are patients with biventricular pacemakers pacemaker dependent?
No
160
What patients are approved for CRT
Patients with...
1) Class I-Class IV heart failure
2) EF less than 50%
3) QRS greater than 130ms
4) AV block that requires pacing
161
What is Micra? What patients could benefit from Micra?
```
Leadless RV pacer that is MRI compatible.
Used for patients with...
1) Permanent a-fib
2) High grade block
3) Symptomatic AV block
```
162
Where are the lead placed in an Internal Cardioverter Defibrillator (ICD)
Right ventricle and/or right atrium
163
What electrical activity does an ICD measure?
The R-R interval and categorizes the rate as too slow, too fast, or normal
164
If an ICD detects a high number of short R-R intervals within a set time, what will it do?
It will initiate an anti-tachycardic event (rapid pacing or a shock)
165
If an ICD detects a high number of long R-R intervals within a set time, what will it do?
Trigger antibradycardic therapy
166
How can you differentiate an ICD from a pacemaker using an X-ray?
An ICD has a thick coil used for defibrillation in the right ventricle
167
Indications for ICD placement (6)
1) Significant v-tach or v-fib
2) EF less than 35%
3) Post-MI EF less than 30%
4) Hypertrophic cardiomyopathy
5) Brugada syndrome
6) Long QT syndrome
168
How do subcutaneous ICDs respond to v-tach
Terminates v-tach only via defibrillation, no rapid pacing capabilities
169
Subcutaneous ICDs are not suitable for which patients? (3)
1) Patients with primary v tach
2) Patients who need CRT
3) Patients who respond to rapid pacing
170
Advantages of subcutaneous ICD
Avoid the vascular system thus avoid...
- Vein thrombosis/stenosis
- Lead failure
- Infection
171
Disadvantages of subcutaneous ICD
- Larger
- Shorter battery life
- Limited long term evaluation
172
How do subcutaneous ICDs respond to magnets?
Temporarily disabled
173
Source of 99% of OR EMI
Bovie
174
Which bovies produce EMI?
Unipolar
175
Sources other than bovies that cause EMI
- Therapeutic radiation
- Lithotripsy
- RF ablation
- TENS unit
- ECT
176
Effects of EMI on an ICD
It can trigger the ICD to deliver antitachycardic therapy inappropriately
177
Effects of EMI on pacemakers
- Can lead to oversensing which can cause a period of asystole
- Increased rate modulation
178
What is noise reversion?
When a pacemaker triggers asynchronous pacing in response to repetitive sensing at a high rate
179
Procedures at high risk for EMI
- Major surgeries above umbilicus with bovie use
- Radiofrequency ablation
- Lithotripsy
- TURP/hysteroscopy
- MRI
180
Which procedure at risk for EMI poses the greatest risk to pacemaker devices?
Therapeutic radiation
181
Methods to minimize EMI
- Place bovie grounding pad 15-25cm away from device
- Ensure bovie path does not cross the pulse generator or leads
- Try to avoid unipolar bovie
- Use bovie in short bursts less than 5 seconds
182
Risks of placing a magnet on pacemakers
- R on T phenomenon
- V-tach/v-fib
- Decreased cardiac output
183
What capabilities of an ICD is turned off with magnet placement?
Antitachycardic detection/therapy
184
If a patients ICD is turned off with a magnet, what are the protocols until the ICD is turned back on?
Patient must have continuous EKG monitoring and defibrillation equipment readily available
185
If defibrillation is necessary in a patient with an ICD, how should the pads be oriented?
In an anterior-posterior direction to avoid direct current to the device
186
What function of the ICD is not affected by magnet placement?
Antibradycardic
187
What does it mean if no tones are heard when a magnet is placed on a Boston Scientific ICD
Either the magnet is not correctly placed or the magnet mode is not enabled - the ICD is still functional
188
What does it mean if a Boston Scientific ICD produces a tone that is synchronous with the patients QRS when a magnet is in place?
The ICD is temporarily disabled but will resume normal therapy with magnet removal
189
What tone is heard when a magnet is placed properly on a Medtronic ICD?
A constant tone for 10-30 seconds
190
What does it mean if a pulsing or alternating high/low tone is coming from a Medtronic ICD?
Device malfunction
191
What happens when a magnet is placed on a combined ICD/Pacemaker
- Antitachycardic function is disabled on ICD
| - NO effect on pacemaker
192
All ICDs should be interrogated within __ months of an elective surgical procedure
6
193
All pacemakers should be interrogated within __ months of an elective surgical procedure
12
194
Guidelines for a patient with a pacemaker having a low EMI risk surgery
Prophylactic placement not necessary
195
Guidelines for a patient with an ICD having a low EMI risk surgery
Consider prophylactic magnet placement
196
Guidelines for a patient with a pacer/ICD combo having a low EMI risk surgery
Consider prophylactic magnet placement
197
Guidelines for a pacer-dependent patient having a high EMI risk surgery
- Consider magnet placement if rapid asynchronous pacing is available
- Limit bovie to short bursts
198
Risks of a pacer-dependent patient having a high EMI risk surgery
Oversensing and asystole
199
Guidelines for a non-pacemaker dependent patient with a pacemaker having a high EMI risk surgery
Prophylactic magnet placement not necessary
200
Guidelines for a patient with an ICD having a high EMI risk surgery
Place magnet and have continuous access to defibrillator
201
Guidelines for a patient with an ICD/pacemaker combo having a high EMI risk surgery
- Magnet can be placed to disable ICD
- Use bovie in short bursts
- Place pacemaker in asynchronous mode if necessary
202
Which patients should be evaluated by the Electrophysiology Service immediately postoperatively before leaving a cardiac monitored unit (4)
1) Any device that was programmed off
2) Any patient that required external defibrillation or CPR
3) Any patient having cardiothoracic or major vascular surgery
4) Any emergency surgery with EMI above umbilicus
203
Any patient exposed to monopolar electrocautery should be evaluated within __ month(s) of the procedure
1
204
What are the recommendations when surgery must proceed but an implantable cardiac device is not known?
- Obtain EKG to determine if the patient is pacemaker dependent
- Stat chest X ray to determine if there is an ICD coil or to identify the device
205
Incidence of Congenital Heart Disease
8 in 1,000 live births
206
What percentages of CHD patients survive into adulthood
85%
207
Most frequent Congenital Heart Disease
Ventricular septal defect
208
The majority of congenital cardiac shunts are...
Left to right
209
How do left to right shunts affect pulmonary blood flow?
Increase
210
Patients with left to right shunts are at risk of developing...
CHF because of a VOLUME overloaded ventricle
211
What Congenital Heart Disease is a right to left shunt
Tetralogy of Fallot
212
How does Tetralogy of Fallot (right to left shunt) affect pulmonary blood flow
Decrease
213
Patients with a right to left shunt have a ______ overloaded ventricle
Pressure
214
Large ventricular septal defects cause early...
CHF
215
Manifestations of CHF as a result of ventricular septal defect
- Poor growth
- Tachypnea
- Sweating with feeding
216
Delayed treatment of ventricular septal defect results in increasing...
PVR
217
Consequence of late or no repair of ventricular septal defect
Eisenmenger's with cyanosis and polycythemia. basically, the increasing pulmonary vascular resistance from untreated VSD turns into pulmonary hypertension, which turns the previously left-to-right shunt into a right-to-left shunt which shunts deoxygenated blood over to the left heart to be pumped throughout the body and causes cyanosis
218
How does pulmonary vascular resistance change as we age?
It starts out very high in the womb and steadily decreases as we age due to arborization
219
What is atrioventricular canal defect?
When the heart contains 1 large, elongated valve instead of 4 separated chambers. This causes mixing of blood at atrial and ventricular levels
220
AV canal defect is commonly associated with what genetic disorder
Trisomy 21 (Down syndrome)
221
What is involved in the repair of AV canal defect
Closing the atrial and ventricular septal defects and making 2 AV valves from the one large one
222
What can occur with late or inadequate repair of AV canal defect
Elevated PVR
223
What four issues are involved in Tetralogy of Fallot?
1) Ventricular septal defect
2) Pulmonary stenosis
3) Overriding aorta
4) Right ventricular hypertrophy
224
What does the repair of Tetralogy of Fallot involve?
Closing the ventricular septal defect and relieving the pulmonary stenosis
225
Pulmonary stenosis in Tetralogy of Fallot can occur at what 3 levels?
- Infundibular (muscular)
- Valve
- Supravalvar
226
What can be caused by a transannular patch in patients with Tetralogy of Fallot?
It will cause free pulmonary insufficiency which can lead to right ventricular dilation, tricuspid regurgitation, and right heart failure
227
Why is phenylephrine a great drug to use for kids with Tetralogy of Fallot?
Dropping their SVR causes more blood to bypass the lungs, so phenylephrine helps by increasing SVR and allowing as much blood as possible to get to the lungs and improve O2 saturation
228
What is Transposition of Great Arteries?
Pulmonary artery and aorta are switched in location, so there are 2 separate circulations and deoxygenated blood gets pumped throughout the body
229
What surgical placement may be required to treat Transposition of Great Arteries?
Balloon septostomy
230
What surgery is being used to treat Transposition of Great Arteries in the recent era?
Arterial switch
231
What late problems can occur after an atrial switch (early era surgery) to treat Transposition of Great Arteries?
- CHF if right ventricle can't sustain systemic afterload
| - SVT, a-fib/flutter due to extensive atrial suture lines
232
What is the "Achilles heel" of the arterial switch procedure to treat Transposition of Great Arteries?
Coronary artery transfer
233
Late problems from an arterial switch procedure to treat Transposition of Great Arteries
- Supravalve stenosis of aorta or PA
- Aortic valve insufficiency
- Coronary ostial stenosis
234
What is the 1st procedure done to treat a right sided single ventricle lesion?
Blalock-Taussing shunt. This redirects blood from the subclavian or carotid artery to the pulmonary artery to help increase blood flow to the lungs
235
What is the 1st procedure done to treat a left sided single ventricle lesion?
Norwood series - a 3 stage procedure to create a new functional systemic circuit
236
What is the 2nd stage of treatment used for both right and left side single ventricle lesions?
Glenn anastamos - a connection between the superior vena cava and the right main pulmonary artery to increase pulmonary blood flow
237
What is the ultimate result of treatment for single ventricle lesions?
Fontan - diverts the blood from the right atrium to the pulmonary arteries without passing through a right ventricle
238
What is necessary for a successful Fontan?
- Good ventricular function since blood is pushed through both circulations by only one ventricle
- Low PVR
239
Calculation for transpulmonary gradient
Pulmonary artery pressure - Left atrial pressure
240
Causes for failure of a Fontan procedure
Reduction of ventricular function --> expansion of vascular volume --> increased LVEDP --> increased LA pressure --> increased PA pressure --> increased CVP --> edema, hepatic congestion, protein losing enteropathy
241
Symptoms of Fontan failure
- Fatigue
- Headache
- Swelling
242
What should be avoided during inhaled induction of a patient with a CHD?
Avoid overdose because that will decrease blood pressure thus pulmonary blood flow
243
Monitors other than standard ASA that are often used for a patient with a CHD
- Arterial line
| - BIS
244
The lowest PVR exists at what lung volume?
Functional residual capacity
245
Are most cases of SBE attributable to invasive procedures?
No
246
Cardiac conditions requiring prophylaxis for SBE
1) Prosthetic cardiac valve
2) Previous SBE infection
3) Congenital Heart Disease (unrepaired, repaired within last 6 months, or repaired with residual defects)
4) Cardiac transplantation with valvulopathy
247
What dental procedures should SBE prophylaxis be used for?
Any dental procedures with bleeding potential (i.e. gums, mucosa)
248
What surgical procedures is SBE prophylaxis REQUIRED for?
1) Tonsillectomy/adenoidectomy
2) Any involving respiratory mucosa (sinus)
3) Rigid bronchoscopy
4) Infected skin or tissue
249
Oral antibiotic order for SBE prophylaxis
Amoxicillin one hour before surgery
250
IV antibiotic order for SBE prophylaxis
Ampicillin 30 minutes before
251
Oral antibiotics available for penicillin allergic patients for SBE prophylaxis
-Clindamycin
-Cephalexin
-Azithromycin
-Clarithromycin
Take 1 hour before
252
IV antibiotics available for penicillin allergic patients for SBE prophylaxis
-Clindamycin
-Cefazolin
-Ceftriaxone
Take 30 min before
253
Is SBE prophylaxis required for a 2 year old s/p BT shunt for BMT and adenoidectomy?
Yes - at risk patient and at risk procedure
254
Is SBE prophylaxis required for a 10 year old for cysto and ureteral reimplantation?
No - neither patient nor surgery is high risk for SBE
255
Is SBE prophylaxis required for a 4 year old with a small VSD and murmur having a dilation of esophageal stricture s/p TEF repair?
No - neither patient nor surgery is high risk for SBE
256
Why should NM blockade reversal with neostigmine/glycopyrrolate be avoided in a cardiac transplant?
It can cause asystole due to increased levels of Ach
257
You are on CPB and the Hgb is 7. Which of these would lead you to transfuse?
A. Temp 32C
B. MVO2 80
C. Reservoir volume 200ml
D. MAP 65
C Reservoir volume 200ml
258
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Which monitor is the most important for CPB?
A. ECG
B. A line
C. Temp
D. BIS
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B. A line
259
How does venous blood flow into a CPB reservoir?
Gravity drainage
260
When should the heat exchanger cool the patient?
While they are on CPB
261
When should the heat exchanger warm the patient?
As the surgeons are finishing the operation and the patient is about to come off CPB
262
What surgeries is left heart bypass used for?
Descending aortic surgeries
263
Where does blood flow out of during left heart bypass?
Left atrium
264
Where is blood reinfused during left heart bypass?
Femoral artery
265
What functions of CPB are not available during left heart bypass?
Oxygenator, some have heater/cooler
266
What monitor would not be useful if the patient was on left heart bypass with the subclavian included?
Left radial arterial line
267
Alternatives to left heart bypass
- Clamp and sew
| - DHCA (deep hypothermic cardiac arrest)
268
Patients in respiratory failure would be on what type of ECMO?
VV
269
Patients in heart failure would be on what type of ECMO?
VA
270
What additional care is needed for ECMO?
- Systemic heparinization
| - Significant ICU care
271
If you are using a right axillary cannula for CPB, where must you put your aline to ensure adequate perfusion?
Left radial or femoral
272
Why should you rewarm patients slowly when coming off CPB?
For brain protection - evidence shows that if you over -warm the brain the risk of stroke doubles
273
A vent may be used for a patient with what valvular disorder?
Aortic regurgitation to drain the heart if it is getting too full
274
What are the functions of a tack?
Inserts into the aorta and allows cardioplegia and de-airing at the end of the procedure
275
Functions of ECG monitoring during CPB
Allows assessment of ischemia and asystole
276
Why is hypothermia used during CPB?
To improve tolerance of prolonged non-pulsatile blood flow and decrease ischemic injury to brain, heart, and kidneys
277
The target hypothermic temperature used for CPB is related to what?
Expected duration of procedure
278
Temperature goal when mild/tepid hypothermia is used
34-36C
279
Temperature goal when moderate hypothermia is used
30-34C
280
Temperature goal when DHCA is used
18C
281
What part of the body is most sensitive to ischemic insult?
Central nervous system
282
What does the cerebral oximeter give us an indication of?
The oxygenation in the frontal lobe of the brain
283
Why do we monitor PA pressures on CPB?
To assess how full the heart is getting. For ex, if the PA mean is above 10 on CPB, it is either wedged or there is too much volume in the heart and it needs to be drained
284
What is the perfusionist administering in their fluids that would cause us to expect reasonable diuresis in patients on CPB?
Mannitol
285
How often are labs and ACTs checked while the patient is on CPB?
Every 30 minutes
286
Important labs to assess while on CPB
- Lactate
- Glucose
- Acid-base status
- Potassium
287
Which lab, important during CPB, is a global indicator of perfusion
Lactate
288
Why is insulin a standard drip for cardiac operations?
The glucose tends to be very high in these patients because the operations are so stressful on the body
289
What is the best intravascular volume estimator that we have during CPB?
Volume in the CPB reservoir
290
MOA of Heparin
Inhibits thrombin via antithrombin III
291
If a patient with HIT must have surgery, what are some heparin alternatives?
- Lepirudin
- Argatroban
- LMWH
- Danaparoid
- Ancrod
292
If a patient on CPB is coagulopathic, how do we redose heparin?
On a time basis
293
Normal ACT values
100-140
294
ACT values adequate to go on CPB
380-480
295
ACT is affected by what components?
- Temperature
- Platelet function
- Hemodilution
296
Where is the most common placement of an arterial cannula used for CPB?
Ascending aorta, distal to the PA
297
What location of arterial cannulation for CPB poses an increased risk of stroke?
Femoral artery
298
Where can venous cannulas used for CPB be placed?
In any large vein that will allow gravity drainage of blood to the reservoir
299
What is bicaval cannulation?
2 separate cannulas in the SVC and IVC used when maximal drainage of the heart is needed
300
Common placement of venous cannulas for minimally invasive procedures or repeat sternotomies
SVC via RIJ or femoral
301
Where is a vent typically placed
In the right upper pulmonary vein and down into the left atrium
302
Function of a vent during CPG
Removes blood that accumulates in the heart to prevent distention injury
303
Flow of antegrade cardioplegia
Normal direction - ascending aorta --> coronary arteries
304
Flow of retrograde cardioplegia
Coronary sinus --> coronary veins --> aorta
305
What determines the choice of antegrade vs retrograde cardioplegia
- Surgical procedure
| - Patient ventricular function status
306
Why is infusion pressure measured during retrograde cardioplegia?
To prevent overinflation and injury to the coronary sinus
307
How is infusion pressure of retrograde cardioplegia measured
With the CVP transducer monitor
308
Where is temperature measured during CPB?
- Nasopharyngeal
- Bladder
- PA
- Arterial inflow
- Venous return
309
Why is temperature measured in so many places during CPB?
To ensure temperature change is equally distributed and to monitor speed of temp changes
310
What pressors are used to maintain MAP during CPB? Why?
Phenylephrine and vasopressin because they don't have beta effects
311
The hemoglobin trends as low as __ during most procedures with CPB
7
312
What procedures use axillary cannulation for CPB?
Major aortic surgeries such as...
- Aortic dissections
- Aneurysms
- Arch procedures
313
When weaning from CPB, what component of the CPB circuit decreases as the patient's blood pressure increases
Arterial inflow rate
314
What is the first line alpha agent used to increase SVR when weaning from CPB?
Norepinephrine
315
Why is phenylephrine usually not used when weaning a patient off CPB?
Because we don't want strictly unopposed alpha agonism and too large of an increase in SVR
316
What are the indications for using phenylephrine when weaning a patient off CPB?
- Dilated cardiomyopathy
| - Systolic anterior motion of mitral valve
317
What inotrope do we use when weaning patients off CPB if we also need chronotropy?
Epinephrine
318
What inotrope would we use to wean patients off CPB if they had a high SVR and poor heart function?
Milrinone
319
What patients would need inhaled Flonan/NO when weaning off CPB?
Patients with pulmonary hypertension and right heart failure
320
Functions of an intra-aortic balloon pump
- Augment myocardial perfusion
- Increase coronary blood flow during diastole
- Unload left ventricle during systole
- Improve systemic perfusion
321
Effects of intra-aortic balloon pump during inflation
- Increase diastolic pressure
- Increase O2 supply
- Increase systemic perfusion pressure
- Increase baroreceptor response
- Decrease sympathetic stimulation
322
Effects of intra-aortic balloon pump during deflation
- Reduce aortic systolic pressure
- Reduce duration of isovolemic contraction
- Increases SV/EF
323
Effect of intra-aortic balloon pump on lactate use
Increase
324
Effect of intra-aortic balloon pump on arterial distensibility
Increase
325
Indications for intra-aortic balloon pump
- Cardiogenic shock
- Failure to wean from CPB
- Pre-op stabilization
- Cardiac support during coronary angiography
- Bridge to transplant
326
Contraindications to an intra-aortic balloon pump
- Aortic insufficiency
- Dissecting descending aortic aneurysm
- Severe atherosclerosis
- AAA
- Trauma
327
How does protamine reverse heparin
Via acid/base mechanism
328
Hallmarks of protamine reaction
- Pulmonary HTN
| - Systemic hypotension
329
What are the only blood products that can be given during CPB?
- RBC
| - FFP
330
What lab studies are beneficial when managing coagulation? (5)
- Antithrombin III level
- Platelet count
- Fibrinogen
- INR
- TEG
331
Most common valve repair done without CPB
Aortic valve repair
332
Example of an aortic surgery that can be done without CPB
TEVAR (Thoracic Endovascular Aortic Repair)
333
What blood product can be used as a source of antithrombin III
FFP
334
What is the most important component used to predict failure of weaning from CPB
Type of surgical procedure
