9. Cardiac Intensive Care Flashcards
1
Q
When is PVR lowest?
A
Functional residual capacity
2
Q
What happens to PVR at lung volumes below functional residual capacity?
A
Increases due to reactive vasoconstriction
*Underinflation of lungs, atelectasis and alveolar hypoxia
3
Q
What happens to PVR at lung volumes above functional residual capacity?
A
Increases due to secondary vasoconstriction from vascular stretch
*Overinflation and increased airway pressure
4
Q
What can cause an elevated SVC pressure without an elevated LA pressure?
A
- Anything that impedes pulmonary blood flow or cases distortion of PA (thombus)
- Elevated PVR
- Pleural effusion
- Atelectasis
- Hyperinflation
- PV stenosis
5
Q
What can cause an elevated SVC pressure + elevated LA pressure?
A
- Pericardial tamponade
- JET
- Ventricular dysfunction
- Severe AVVR
6
Q
What can happen to a Glenn patient with elevated SVC pressures?
A
Systemic desaturation due to opening of vestigial veins that drain venous blood to heart
7
Q
What types of surgeries have a higher incidence of post-operative JET?
A
- ToF repair
- VSD repair
- CAVD repair
8
Q
Management of JET?
A
- Hypothermia
- Diminish catecholamines (sedation)
- Anti-arrhythmic agents with goal of AV synchrony: Amiodarone, procainamide
9
Q
What tachydysrhythmia is more common in patients with asplenia?
A
EAT
10
Q
What anatomy should you think of with DORV, common AV canal, PA, TAPVR?
A
Asplenia
11
Q
What post-op complication would you consider for all these scenarios:
- 2 m/o s/p truncus repair
- 6 m/o s/p TGA/VSD repair
- 5 m/o s/p CAVD repair
- Neoante infracardiac TAPVR repair?
A
Post-op pulmonary HTN
12
Q
Expected CVP & LA pressure following ToF repair?
A
Elevated CVP
Normal LA pressure
*Restrictive RV physiology
13
Q
Expected CVP & LA pressure following TAPVR repair?
A
LA pressure > CVP
*LA/LV noncompliant and borderline hypoplasic… higher filling pressure needed
14
Q
Expected CVP & LA pressure following TGA repair?
A
LA pressure > CVP
*Some degree of LV dysfunction (moreso older patients)
15
Q
Expected CVP & LA pressure following ALCAPA repair?
A
LA pressure > CVP
*LV dilated with significant dysfunction causing elevated filling pressure
16
Q
Expected CVP & LA pressure following CoA + VSD repair?
A
LA pressure > CVP
17
Q
What are the expected changes in CVP and LA pressure in pulmonary HTN?
A
Elevated CVP
Normal or slightly elevated LA pressure
18
Q
What would AP collaterals, residual VSD following repair, LV dysfunction and coronary ischemia due to filling pressures (LA pressure)?
A
Increase
19
Q
Describe the 2 phases to HTN following coarct repair
A
- Surgical stimulation of sympathetic nerve fibers in tissue of aortic isthmus… release of epi/norepi
- After initial 24 hours, increase in renin and elevated diastolic pressure, also assocaited with mesenteric arteritis
20
Q
What can be done in the pre-operative period to manage initial post-op HTN in patients after CoA repair?
A
Propranolol (neutralizes norepi and epi release following surgery)
21
Q
Causes of elevated PA pressure after Fontan with an abnormal transpulmonary gradient (>5)?
A
- Elevated PVR
- PA distortion (thrombus)
- Pulmonary issues (pleural effusion, pneumothorax, atelectasis)
- Pulmonary venous obstruction
22
Q
Causes of elevated PA pressure after Fontan with a normal transpulmonary gradient (but normal LA pressures)?
A
- Ventricular dysfunction
- Diastolic dysfunction (unfavorable mass/volume changes)
- AVVR
- Subaortic stenosis
- AV dyssynchrony
- Pericardial effusion
23
Q
What can cause giant V waves on a CVP tracing?
A
TR
24
Q
A-wave on CVP tracing caused by?
A
Atrial contraction
25
C-wave on CVP tracing caused by?
Ventricular contraction against closed tricuspid valve (valve bulges into RA)
26
V-wave on CVP tracing?
Atrial filling
27
X descent on CVP tracing?
Due to tricuspid valve being pulled way from RA during ventricular systole (follows the c-wave)
28
Y descent on CVP tracing?
Blood filling RV
29
What causes cannon a waves on CVP tracing?
1. RA contracting against an obstructed tricuspid valve- TS, RA masses, RA myxoma, complete heart block, AV dyssynchrony
2. Resistance to RV filling- Pulmonary HTN or PS
30
Equation for oxygen excess omega?
Oxygen excess omega = Oxygen delivery/Oxygen consumption
or
Oxygen excess omega = SaO2/(SaO2 – SvO2)
31
Which mediators are decreased in pulmonary HTN?
1. Prostacyclin
2. Matrix metalloproteinases
3. NO
4. Thrombomodulin
32
Which mediators are increased in pulmonary HTN?
1. TGF-B
2. Endothelin
3. Serotonin
4. Thromboxane A2
5. Von Willebrand factor
6. P-selectin
7. Plasminogen activating inhibitor
8. Fibrinopeptide A
9. Tissue plasminogen activator
10. Angiotensin II
11. Epinephrine
12. Insulin-like growth factor
13. Basic fibroblast growth factor
14. Platelet-derived growth factor A
33
What needs to be ruled out prior to initiating management for post-operative pulmonary HTN?
Any residual VSD
*Reducing PVR with a significant residual VSD can exacerbate hemodynamic instability
34
What do class I antiarrhythmics do?
Block fast Na channels (local membrane stabilizing activity)
35
What class antiarrhythmic are quinidine, procainamide, disopyramide?
IA
36
What do the IA antiarrhythmics do?
Moderate phase 0 depression/immediate slowing of conduction/prolongation of repolarization/ prolongation of AP and effective refractory period
37
What class antiarrhythmics are lidocaine, mexiletine, phenytoin?
IB
38
What do the IB antiarrhythmics do?
Minimal phase 0 depression/little slowing of conduction/shortening of repolarization/shortening of AP and effective refractory period
39
What class antiarrhythmics are flacainide, encainide, propafenone?
IC
40
What do the IC antiarrhythmics do?
Marked phase 0 depression/marked slowing of conduction/little effect on repolarization/little effect on AP and effective refractory period
41
What are the class II anti-arrhythmics?
B-blockers
42
Which class of antiarrhythmics prolongs the duration of the cardiac action potential and repolarization, but not conduction (the block K channels)?
Class II
43
Name 3 class III anti-arrhythmics
1. Amiodarone
2. Sotalol
3. Bretylium
44
What class of antiarrhythmics blocks slow Ca channel and increases the effective refractory period of the AV node, slows conduction and rescues automaticity of the sinus/AV nodes?
Class IV
45
What class of antiarrhythmic is verapamil?
Class IV
46
MOA of ASA?
Acetylation of cyclo-oxygenase to inhibit production of thromboxane A2, a platelet aggregator
47
MOA of Heparin?
Mucopolysaccharide that increases the rate at which antithrombin III neutralizes thrombin, factor X and also IX, XI, and XII
48
MOA of Streptokinase?
Interacts with plasminogen to result in plasmin complex
49
MOA of TPA?
Binds to fibrin
50
MOA of Warfarin?
Interferes with posttranslational modification of vitamin K dependent coagulation factors (II, VII, IX, X and proteins C and S
51
Name causes of a low CVP
1. Pressure transducer above level of heart
2. Low intravascular volume
3. Inadequate preload
4. Transducer improperly calibrated
5. Catheter malfunction
52
Causes of reduced O2 saturation in the RA?
1. Increased O2 extraction
2. Catheter tip in CS
3. Anemia
4. Decreased arterial O2 saturation with normal A-V O2 difference
53
What does increased O2 delivery do to O2 saturation in the RA?
Increases it
54
Causes of increased O2 saturation in the RA?
1. Atrial level L-R shunt
2. Anomalous pulmonary vein
3. LV-RA shunt
4. Increased O2 delivery
5. Decreased O2 extraction
6. Increased dissolved O2 content
7. Catheter tip position near renal vein
55
What types of VSD are most likely to result in complete heart block following repair?
1. Canal-type VSD with straddling tricuspid valve
| 2. Perimembranous VSD (bundle of His courses posterior-inferiorly to defect)
56
What type of VSDs have the least likely risk for heart block following repair?
Muscular/subpulmonary
57
Following repair of what defect would you expect tachycardia and elevated LA pressures?
TAPVR
Left sided strictures are borderline hypoplastic and non-compliant
58
What is neosynephrine?
Pure alpha agonist
59
When is neosynephrine useful?
Decreased pulmonary blood flow in the presence of an unrestrictive VSD or single ventricle (increases SVR and results in increased pulmonary blood flow)
60
What should be done for an infant with ToF absent PV in respiratory distress?
Prone- Can decrease proximal airway obstruction
61
Why do infants with ToF absent PV have significant respiratory distress?
- Enlarged main and branch PAs compress the proximal airways
| - Distal airway disease due to serpiginous pulmonary arterioles encircling the distal bornchioles
62
Angiotensin II, leukotrienes C4, D4, E4, prostaglandin F2alpha, thromboxane A2, and serotonin all do what to the pulmonary vasculatures?
Vasoconstrict
63
Acetylcholine, bradykinin, prostaglandins E1, E2 and I2, and NO all do what to the pulmonary vasculature?
Vasodilate
64
True or False: Epinephrine, norepinephrine, endothelins, histamine and prostaglandin D2 can have variable effect on the pulmonary circulation?
True
65
What should be done first in a Fontan with elevated PA pressures and tolerable hemodynamics?
Echo- Assess for pericardial tamponade and function
* CXR to assess pulmonary parenchyma
* If echo/CXR normal, can do cath to rule out thrombosis and stenosis of PAs
66
Why is milrinone risky in a baby with complete mixing physiology and a BP of 68/22?
-Reduced CPP
* BP shows wide pulse pressure/low diastolic pressure suggesting excessive PBF
* IV milrinone will cause afterload reduction and lower diastolic even more, which will decrease CPP
67
What would you consider for an infant with complete mixing physiology and a BP of 68/22?
- IV dopamine
- pRBCs
- Volume
- Decreasing sedation
68
What are potential findings after a Ross-Konno?
- Residual VSD or RVOT narrowing: LVOT enlarged using a patch
- Poor LV function: Concentric hypertrophy due to AS, suboptimal myocardial protection during bypass
- Coronary ischemia: Coronary implantation
- Neo-AI
69
True or False: Pulmonary HTN following Ross-Konno is uncommon and unexpected?
True
70
What are 4 potential causes of elevated LA pressure and tachycardia in a 4 week old after ASO/VSD closure?
- Pericardial tamponade: Elevated RA/LA pressures + Tachycardia
- JET: Elevated filling pressures due to AV dyssynchrony
- LV may be unprepared at 4 weeks with higher filling prsesures
- Myocardial depression from bypass or coronary transfer
71
True or False: AP collaterals can result in elevated LA pressure in a TGA patients?
False- May have AP collaterals that result in some LV volume loading, but unlikely to cause an elevated LA pressure
72
JET is more common in infants with corrective surgeries involving what?
VSD closure
73
Infants with asplenia or repair of TAPVR have an increased likelihood of what arrhythmia?
EAT
74
What factors suggest post-operative re-entrant SVT?
- Sudden onset
| - Response to adenosine
75
V-tach in the post-operative period is usually associated with what?
Myocardial ischemia
76
What types of CHD have increased association with ischemic bowel syndrome?
- Left-sided obstructive lesions: HLHS, CoA, AS
- Truncus: Runoff to PAs and truncal regurgitation result in low diastolic pressure and suboptimal perfusion to mesenteric tract
77
True or False: ToF is unlikely to be associated with ischemic bowel syndrome?
True
*Especially in absence of excessive pulmonary blood flow from AP collaterals
78
What inotrope increases myocardial oxygen consumption the least?
Milrinone
*Doesn't usually increase HR or BP (which are components of rate pressure index)
79
What is an indirect determinant of myocardial oxygen consumption?
Rate pressure index
80
What are 2 components of rate pressure index?
HR
| BP
81
What are the 3 assumptions used when calculating Qp:Qs in single ventricle physiology patients?
1. a-v O2 difference between aorta and mixed venous source is 25%
2. No significant pulmonary venous desaturation (PV sat is 95-100%)
3. Aortic and PA saturations are equal (aortic by pulse ox)
82
What is the equation for Qp:Qs?
Ao-MV saturation/PV-PA saturation
83
After a bidirectional Glenn, what can cause increased SVC pressure with a large transpulmonary gradient?
- Elevated PVR
- Pulmonary venous obstruction
- Pulmonary issues: Pleural effusion, pneumothorax, thrombosis within cavopulmonary circuit
84
Poor ventricular compliance could raise SVC pressure, but what other pressure would also be increased?
LA
85
What are the 3 most common risk factors for irreversible pulmonary HTN?
- Increased pulmonary blood flow
- Increased PA pressure
- Cyanosis
*Others include pulmonary hypoplasia and pulmonary venous hypertension
86
What are some forms of CHD that have the 3 most common risk factors for pulmonary HTN to persist after surgery (increased pulmonary blood flow, increased PA pressure, cyanosis)?
- Older TGA
- CAVC
- Truncus
87
What change in SVR can lead to a hypercyanotic spell in ToF?
Decreased SVR
*Leads to increased R-L shunting and cyanosis
88
What are some options for management of a hypercyanotic spell?
1. B-Blocker: Decrease HR/RVOT narrowing
2. Neosynephrine (alpha agonist): Increase SVR and force more flow to pulmonary circulation
3. O2: Helps if any issues from pulmonary dsiease
4. Fluids/pRBCs: Increase flow out narrowed RVOT and improve oxygenation
89
What would happen if isoproterenol was used during a hypercyanotic spell?
Could exacerbate cyanosis
* Vasodilator: Decreased SVR
* Tachycardia
90
What are etiologies for elevated LA pressures?
1. LA outlet obstruction (mitral stenosis)
2. LV dysfunction (systolic or diastolic)
3. Hypoplasia of LV
4. Pericardial tamponade
5. AV dyssynchrony
91
What type of RV pathophysiology is seen after ToF repair?
Restrictive
*RV is noncompliant and has significant diastolic dysfunction
92
What is the relationship between pericardial volume and pressure?
Curvilinear
*Pericardial pressure doesn't increase with volume until a certain volume threshold is reached, then the pressure rapidly increases with further increase in volume
93
What causes HTN after a CoA repair?
Excess catecholamines
94
What is often used to treat HTN after CoA repair?
B-blockers: Esmolol
-Vasodilators like nitroprusside or hydralazine can also be used
95
What should be considered as a cause for desaturation in a child with Glenn physiology?
Decompressing venous collaterals
*Any increase in PVR can open these
96
How does a low paCO2 result in desaturation in a Glenn patient?
- Low PaCO2 will reduce cerebral blood flow
| - This then indirectly reduces pulmonary flow which reduces saturation
97
What pharmacologic agents have an efficacy for JET?
1. Amiodarone
2. Procainamide
3. Digoxin
*Adenosine may help diagnose, but won't treat
98
What non-pharmacologic interventions help with JET?
1. Hypothermia
| 2. Sedation
99
If you plot lung volumes on the X axis and PVR on the Y axis, what shape is the curve?
U
100
True or False: An infant with moderate TR can have a dilated RA without significantly elevated RA pressure?
True
*Relatively compliant RA
101
What happens to the atrial pressures in restrictive cardiomyopathy?
Elevated
102
True or False: A large pericardial effusion will have low RA pressures?
False- Elevated
103
In chronic dilated cardiomyopathy, what happens to the atrial pressures?
Elevated
104
What needs done after TAPVR repair with an elevated PASP and normal LA pressure?
Echo or cath to rule out any residual PV obstruction
*Pulmonary HTN occurs often, but gradient needs evaluated
105
What must be done prior to starting therapy for pulmonary HTN (iNO, milrinone, sildenafil, etc) after TAPVR repair?
Ensure there is no residual PV obstruction
106
What can be used in the setting of catecholamine-resistant shock after CPB?
- Vasopressin
- Steroids
- Thyroxine
- ECMO
107
What is commonly seen on ECG following ToF and Truncus repair?
RBBB
-Significant incisions into RV muscle
108
What is commonly seen on ECG following subaortic muscle resection?
LBBB
109
Q waves in I and aVL?
ALCAPA
110
True or False: It is normal to see Q waves on ECG following ASO?
False
111
What is the equation for transpulmonary gradient?
PA pressure - LA pressure
112
What does it tell you if a simultaneous PA wedge and ventricular end-diastolic pressure have no gradient?
No stenosis of AV valve or pulmonary venous anatomy
113
True or False: If the transpulmonary gradient is elevated, the PVR is likely elevated?
True
114
Improvement in diastolic function or lusitropy will have what effect on stroke volume?
Increase it
115
Abnormal diastolic function and very dilated atria with intact systolic function should make you think of what?
Restrictive cardiomyopathy
*Atrial pressures are elevated and affect the PA pressures often resulting in pulmonary HTN
116
What are some morbidities associated with restrictive cardiomyopathy?
- CVA
- Atrial tachydysrhythmias
- Sudden death
117
What are vasoconstrictors that are part of the group of mediators that compromise the neurohumoral response in heart failure?
1. Angiotensin II
2. Arginine vasopressin
3. Endothelin
* Vasoconstrictors that result in cardiac stimulation and fluid retention
* Norepinephrine also stimulates the heart as part of this response
118
What 2 effects do BNP have?
1. Vasodilation
| 2. Natriuresis
119
ECG with diminished voltages, T-wave flattening and T-wave inversions following cardiovascular collapse should make you think of what?
Myocarditis
120
ALCAPA ECG?
Q waves in I and aVL
121
What is the main clue to EAT?
Abnormal P-wave axis
*But could be in sinus region mimicking sinus tachycardia
122
What are 3 properties of milrinone?
1. Afterload reduction
2. Inotropy
3. Lusitropy
123
What is an explanation for desaturation and cyanosis after surgical ASD closure?
IVC baffle: Inadvertent closure of ASD by sewing patch to Eustachian valve
*In an IVC-confluent secundum ASD, the posterior rim of the septum primum is often absent and the defect may be contiguous with the IVC
124
What is seen during cath if during ASD closure, a patch is sewn to the Eustachian valve accidentally?
Catheter from femoral vein will enter LA, but not SVC or right heart
125
What echo finding is most specific for cardiac tamponade?
Diastolic collapse of RA/RV
*RA/RV are compliant, so increased intrapericardial pressure leads to collapse when the intracavitary pressures are only slightly higher than those in the pericardium
126
What causes RA collapse in diastole during tamponade?
- At end-diastole (atrial relaxation), the RA volume is minimal, but pericardial pressure maximal
- This causes the RA to buckle
127
When does RV collapse occur in tamponade physiology?
Early diastole
*When RV volume is still low
128
True or False: RV collapse is more specific than RA collapse in tamponade physiology?
True
129
What circumstances might you not see RV collapse in tamponade physiology?
- RV is hypertrophied
| - RV diastolic pressure greatly elevated
130
LA collapse occurs in what % of patients with hemodynamic compromise due to tamponade?
25%
131
When can LV collapse be seen in tamponade physiology?
Cases of regional cardiac tamponade
*Overall less common since LV wall more muscular
132
What is IVC plethora and what does it reflect?
- Dilation and <50% reduction in diameter during inspiration
| - Marked elevation in CVP
133
What change in the IVC can be seen in patients with cardiac tamponade?
IVC plethora- Dilation and <50% reduction in diameter during inspiration
134
Qp:Qs equation?
SaO2-SvO2 – SpvO2-SpaO2
135
For Qp:Qs calculation in complete mixing physiology, what assumptions are made?
- SaO2 = SpaO2
| - SpvO2 = 100%
136
What would expect in a patient with complete mixing physiology and low SVR?
Cyanosis
-Poor pulmonary blood flow
137
How do you manage cyanosis in a patient with complete mixing physiology?
- Increase afterload (alpha-agonist)
| - Lower PVR (iNO)
138
How do you manage inappropriately high saturations in a patient with complete mixing physiology?
-Decrease afterload
139
What are the most common infusion reactions to IVIG?
- Fever
- Chills
- Rash
- Hypotension
140
What can worsen hypotension after IVIG is given for myocarditis?
The use of other afterload reducing heart failure medications
141
Hypotension following IVIG infusion can develop in what time-frame?
1-6 hours from onset of infusion
142
Why are antiplatelets/anticoagulation used in severe heart failure?
Can get embolic events from apical or LA thrombus
143
Describe persistent pulmonary HTN of the newborn?
- Elevated PVR due to lung disease (prematurity, meconium aspiration, etc)
- Leads to R-L shunting via PDA due to elevated PVR and persistent fetal circulation
144
What measures help with PPHN?
- Mechanical ventilation
- Antibiotics
- iNO
- ECMO
145
What should ventricular dysfunction and ventricular ectopy in a neonate post-ASO make you think of?
Coronary ischemia
146
How is echo helpful in assessing for coronary ischemia post-ASO
- Rule out other issues like tamponade
- Assess for ventricular dysfunction
- Assess for new valvular regurgitation (due to papillary muscle ischemia)
*Coronary origins very hard to see after reimplantation
147
What would you expect on ECG for a neonate with coronary ischemia following ASO?
Regional ischemic pattern (ST-T changes)
148
How is definitive diagnosis of coronary ischemia following ASO made?
Cath or CTA
149
What is the recommended management of infracardiac TAPVR?
Surgery
*Septostomy not recommended b/c only palliative and delays surgery
150
How might TAPVR present?
RDS
| PNA
151
What should you always confirm on Echo prior to cannulating an infant to ECMO if able?
Pulmonary veins
*Veins become very hard to see once on ECMO
152
What is the role of PGE in TAPVR?
Can be harmful- increases PBF and reduces PVR which can exacerbate pulmonary venous congestion
153
Transient AV block following cardiac surgery is seen in what % of patients?
2
154
What proportion of patients will have return of AV conduction and in what time frame following transient AV block after surgery?
- Half
| - Around 3 days
155
The incidence of permanent complete AV block is highest with repair of what?
- Lesions near AV node
- Membranous and inlet VSDs
- L-TGA
- AVCD
- ToF
156
If sinus rhythm doesn't return after how many days will it most likely not return following post-operative AV block?
7 days
*Recommend pacemaker implantation for post-op AV block that persists for at least 7 days following surgery
157
What is a rare complication of surgical closure of a PDA what would result in left lung oligemia?
Ligation of the LPA
* CT chest would show a poorly vascularized left lung, residual PDA and ligated LPA
* Angio would have minimal flow to left lung
158
What should raise your suspicion of inadvertent ligation of the LPA during surgical closure of the PDA?
Asymmetric pulmonary blood flow
159
What physiological changes happen with sternal closure?
- Decreased SV
- Decreased CO
- Decreased mean BP
- Decreased cerebral oxygenation
- Increased intrathoracic pressure
- Decreased total lung compliance
160
What does an open chest help with?
- Decompression of the heart
| - Minimizes tamponade physiology
161
How fast and how long do you atrial overdrive pace to convert atrial flutter?
70% atrial cycle length
3-4 seconds
*If you don't have pacing wires, can use esophageal pacing
162
Why is a burst rate of 70% the atrial cycle length used to convert atrial flutter?
To avoid risk of deterioration into atrial fibrillation
163
What is the initial maximal dose of iNO to achieve therapeutic pulmonary vasodilatory effect?
20ppm
*Higher doses associated with increased risk of side effects and no improvement in outcomes
164
What are side effects of iNO?
- Systemic hypotension
- Methemoglobinemia
- Rebound pulmonary HTN upon weaning
- Elevated nitrous oxide
165
How does systemic HTN and decreased stroke volume change pressure-volume loops?
-Taller and narrower
* Systemic HTN (increased aortic pressure) will increase afterload… this increases LV pressure required to open aortic valve
* Aortic valve closes at a higher end-systolic pressure which (without change in inotropic state) yields reduced stroke volume (decreased width of pressure-volume loop)
* End-systolic pressure-volume relationship (contractility slope) remains unchanged
166
What medication can be used in the case of systemic HTN and decreased stroke volume to improve hemodynamics?
Sodium nitroprusside
167
What are agents that increase SVR/afterload and decrease stroke volume?
- Phenylephrine
- Vasopressin
- Epinephrine
168
What effects does sodium nitroprusside have?
Decrease afterload
Improve stroke volume
Improve cardiac output
169
What effect do B-blockers have?
- Slow HR
- Improved diastolic ventricular filling
- Improved coronary artery flow
170
Equation for EF?
SV/EDV
