Week 5 Flashcards
(116 cards)
1
Q
cardiogenic embryonic region
A
mesoderm initially located at the anterior rim of the embryonic disc–the cardiac crescent
2
Q
cardiac crescent
A
an epithelial layer of cardiac progenitor cells (myocardium, pericardium, endocardium)
3
Q
first formation of the heart embryologically
A
a linear heart tube–beats, blood flows, chambers are eventually specified (atrium are oddly located on the bottom)
4
Q
secondary heart field
A
large parts of the RV and OT are derived from secondary (non crescent) precursor cells that migrate into the outflow tract and differentiate into muscle
5
Q
parts of heart derived from cardiac crescent
A
LV, RA, LA
6
Q
parts of heart derived from secondary field
A
RV, OFT
7
Q
important specification gene required for cardiac development
A
Nkx2.5 (homeobox gene)–positional identity
8
Q
what makes the embryo’s first blood cells?
A
the endothelium and endocardium
9
Q
gene important in secondary heart field development
A
ISL1
10
Q
cardiac looping
A
linear heart tube bends anteriorly to the R. driven by differential muscle growth rate. septation and trabeculation begin
11
Q
bulbus cordis
A
the superior portion of the linear heart that becomes the RA/outflow tracts (conus cords) and the PA/aorta (truncus arteriosus)
12
Q
septation
A
remodeling of the heart into four chambers-AV canal, inter ventricular, interatrial, outflow tract separation
13
Q
atrial septation
A
- septum primum grows from dorsal wall of atrium towards AV cushions
- inferiorly incomplete (ostium primum)
- as ostium primum closes, ostium segundum opens centrally
- septum segundum browns down to passively close osmium segundum
14
Q
types of ASD
A
- ostium segundum ASD
- ostium primum ASD
- sinus venosum ASD
15
Q
ostium segundum ASD
A
- most common ASD
- center of septum
- due to incomplete formation of septum segundum or closure of osmium segundum
- if very small, called a PFO
16
Q
ostium primum ASD
A
- second most common ASD
- lower portion of septum
- due to incomplete closure of osmium primum
- associated with cleft/slit in anterior leaflet of MV (makes sense since its inferior)
17
Q
sinus venosum ASD
A
- located in the upper septum
- due to defect in formation of septum primum
- often associated with abnormal pulm vein connection (connection to RA)
18
Q
PFO
A
hole in septum segundum never closes so that pressure can still drive flow through the osmium segundum
19
Q
why is the aorta so asymmetric?
A
intially 5 pairs of symmetric aortic arch arteries are present, but the right side regresses due to endodermal and neural crest signals
20
Q
DiGeorge Syndrome
A
- 22q11 deletion, gene mutation of TBX1
- neural crest migration defects=interruption of aortic arch
21
Q
circulatory changes at birth
A
closure of the ductus arteriosus, ductus venosus, foramen ovale
22
Q
dextrocardia
A
L-R switch of the heart
23
Q
heterotaxy
A
discordance between organ deviation of L-R axis.
a problem
24
Q
situs inversus
A
total body L-R inversion–abnormalities of nodal cilia (similar to kartageners syndrome)
25
valve formation
endothelial cells migrate between endothelium and myocardium where they undergo epithelial-mesenchymal transformation=cellular swellings=endocardial cushions=valve leaflets
--governed by Ras pathway
26
vasculogenesis
formation of new blood vessels from endothelial precursors (angioblasts), embryonic activity
27
angiogenesis
formation of new blood vessels from pre-existing blood vessels. governed by VEGF
28
semaphorins
mediate repulsive signals involved in axon guidance and growth cone collapse.
29
overview of CV morphogenesis
crescent--> linear--> looping--> septation
30
define congenital heart disease
structural abnormalities of the heart present, though not necessarily manifest, at birth. 0.8% of live births affected.
31
what causes CHD?
- mostly multifactorial polygenic predisposition with environmental factors
- some due to single gene or chromosome abnormality
- few due to toxic or metabolic factors
32
volume overload on chambers
- dilation--which can cause arrhythmias
- hypertropy (eccentric)
- ventricular failure (usually biventricular)
33
pressure load on chambers
- hypertrophy
- ventricular compliance changes (decreased)
- ventricular failure
- arrhythmia
34
presentation of ventricular failure in infants
- exercise intolerance (slow feeding, decreased POs)
- growth failure
- venous pressure elevation (interstitial pulmonary edema, hepatomegaly)
35
pulmonary edema in infants vs older kids/adults
infants=interstitial, no rales
| older=alveolar, with rales
36
increased pulmonary flow
- dilates pulmonary arteries (increased susceptibility to pneumonia)- decreased PVR
- pulmonary vascular disease (eisenmenger)
37
eisenmenger syndrome
- chronically increased pulmonary flow or pressure causes pulm. HTN and cyanosis
- decrease in PVR due to arteriolar contraction from VSCM hypertrophy and scarring
- leads to reverse of L to R shunt (R to L now)
38
cyanosis
- decreased O2 delivery per RBC=metabolic acidosis
- can lead to compensatory polycythemia (hyper viscosity, iron deficiency)
- patients look blue
39
categories of acyanotic CHD
- septal defects (L to R shunts): VSD, ASD, PDA
| - obstructive lesions: aortic stenosis, aortic coarctation, hypoplastic left heart
40
what direction do most CHD septal defects flow?
L to R shunts
41
what is important to remember about the systemic circulation when thinking about CHD?
it will always meet its demands through regulatory mechanisms (the pulmonary system can't do this and reacts passively to the systemic needs)
42
L to R shunts
- the systemic system sees the same amount of flow and degree of oxygenation
- the pulmonary system sees more flow and increased oxygenation since blood from RV (that it literally just oxygenated) is being shunted right back through PA with systemic deoxygenated blood
43
small VSD
-generates a large pressure difference between the two ventricles so that there is a loud holosystolic murmur
44
large VSD
- size comparable to aortic valve size
| - the ventricles are pretty much equalized in pressure so that there is no septal murmur.
45
what drives flow in a small VSD?
pressure gradient
46
what drives flow in a large VSD?
because there is no pressure gradient, vascular resistance is the driving force (PVR)
47
ohms law
P=flow x resistance
48
normal development of PVR
PVR decreases after birth with first breath
49
large VSD at birth
PVR drops with first breath, lungs are rapidly filled with blood (increased flow). bc PVR & SVR are equally high, no blood moves through shunt=normal flow--no murmur
50
large VSD month or so after birth
- P is still high but PVR drops so flow increases (murmur).
- because PVR
51
murmurs of large VSD month after birth
holosystolic septal murmur & diastolic murmur of relative mitral stenosis from increased blood flow
52
large VSD years after birth
- high flow and high pressure in pulmonary system eventually leads to pulmonary vascular disease (eisenmenger)--permanent changes that increase resistance
- PVR>SVR so blood travels from RV to LV--causes cyanosis
- RV does more volume work-RVH only
- normal flow=murmur disappears
53
how can one tell the difference between a kid who has gone into eisenmenger syndrome vs one whose VSD has closed?
- closed: S2 splitting
| - eisenmenger: VSD is still open so no S2 splitting occurs
54
ASD
-with normal decrease in PVR, the PAP and RVP also decrease= RV loses its intrauterine hypertrophy=more compliant--more flow towards RV=RVH/RAH via volume overload
55
why are both ventricles hypertrophied in utero?
they are both systemic
56
murmur of ASD
- will hear murmur of relative pulmonary stenosis and relative tricuspid stenosis
- splitting of S2 accentuated
57
PDA
- connection between aorta and PA so pressure is equalized so flow is determined by resistance
- when PVR normally falls, increased flow will occur through pulmonary system
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main difference between PDA and VSD
- VSD flow primarily occurs during systole (holosystolic murmur)
- PDA flow occurs throughout cardiac cycle bc its always open
59
murmur associated with PDA
-continuous murmur--throughout systole and part of diastole (not enough turbulence towards end to make it through entirety of diastole)
60
disease manifestations of L to R shunt disease
- volume overload=increased pulm flow=increased PAP
| - RVP increase=RVH
61
complications of L to R shunt disease
- CHF from P/V or just V overload
- pulm vasc disease
- growth failure
- pneumonia susceptibility
- endocarditis
62
why are kids with shunt defects susceptible to pneumonia
dilated pulmonary arteries compress the bronchioles=reduced clearance of secretions=more prone to infection
63
isthmus of aorta
- area connecting aorta to ductus arteriosus
| - not much blood flow (flow proximal travels up arch branches and flow from DA goes distal)
64
fetal coarctation
- obstruction to aortic outflow (aortic stenosis/bicuspid valve) in late fetal life=decreased anterograde flow through ascending aorta=unhappy brain
- brain "steals" blood from ductus, so that flow goes both antero and retrograde through isthmus
- branch point creates ridge of tissue=coarctation
65
fetal coarctation after birth
PDA closes and narrowed aorta causes decreased blood flow to kidneys=they suspect shock and secrete renin=increased BP to point of HTN
66
why isn't fetal coarctation a huge problem after birth?
- the ductus closes slowly
| - collaterals are able to form that are able to circumvent the block
67
fetal hypoplastic arch
- a much earlier lesion during cardiogenesis leads to decreased flow through the ascending aorta so that the arch is absent or super small
- brain can't steal well because isthmus is too narrowed
68
fetal hypoplastic arch after birth
-with closure of ductus, there hasn't been enough time for collaterals to form=emergency
69
how do we keep a kid with fetal hypo plastic arch alive until surgery to fix it?
prostaglandin E1s prevent the duct from closing
70
cyanotic CHD
1. PBF dependent: tetralogy of fallot
2. PBF independent: great vessel transposition
PBF=pulmonary blood flow
71
PBF dependent cyanotic CHD
- systemic and pulmonary venous return mix a lot
- cyanosis is inversely proportional to PBF
- PBF is proportional to resistance (pulmonary stenosis, increased PVR, pulm venous obstruction, decreased SVR)
- decreased PBF
72
tetralogy of fallot
1. VSD
2. pulmonary stenosis (increased PVR)
3. overriding of the aorta (sits on top of both ventricles near VSD)
4. RVH
73
shunting in tetralogy of fallot
total pulmonary resistance increases due to outflow obstruction=R to L shunt through VS=cyanosis
74
cyanosis in tetralogy of fallot is totally dependent on...
total pulmonary blood flow
75
PBF independent cyanotic CHD
- abnormal connection leading to two separate circulations (MUST BE CONNECTED VIA PFO)
- limited mixing
- cyanosis not proportional to PBF
- usually increased PBF
76
transposition cyanosis is dependent on...
amount of mixing
77
what determines mixing in transposition cyanosis CHD?
1. size of the septal defect--why we create a larger PFO
| 2. ventricular compliances--LV is more compliant bc it is the pulmonary ventricle--the more compliant=more mixing
78
mustard operation
switch the circulation of a transposition at the atrial level
-complications include 1. sewing causes arrhythmias and 2. RV not good for systemic flow
79
lecompte operation
switch the great vessels of a transposition and move coronaries afterwards to prevent kinking
80
cardiomyopathy
primary myocardial disease. a chronic disease of insidious onset with progressive CHF and/or dysrhythmias, often lethal and treatable only via transplantation
81
three types of cardiomyopathy
dilated, hypertrophic, restrictive
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dilated cardiomyopathy
dilation of the heart (all chambers) with systolic dysfunction of the myocardium
83
hypertrophic cardiomyopathy
hypertrophy of the cardiac muscle to the point that the left ventricular wall becomes so stiff that it cannot properly fill during diastole. LV cavity is normal or smaller than normal, while the LA may be dilated
84
restrictive cardiomyopathy
stiffening of the myocardium, usually all of the chambers, due to infiltration and/or replacement of the myocardium by deposition of intracellular or extracellular material or other cell types (cancer).
normal size ventricles and dilated atria
85
which of the cardiomyopathies has decreased LVEF?
dilated
86
which of the cardiomyopathies is associated with HF due to diastolic dysfunction?
hypertrophic & restrictive
87
primary cardiomyopathy
- solely or predominantly a myocardial disorder (main disease target)
- genetic, acquired, both
88
secondary cardiomyopathy
a myocardial disorder associated with a systemic disease
89
DCM genes affected
cytoskeletal elements, sarcomeric elements
90
HCM genes involved
sarcomeric elements
91
arrhythmogenic RV cardiomyopathy
- defect in desmosome protein plakoglobin (defective cellular adhesion)
- RHF with dysrhythmias
- thinned RV-myocytes replaced with fat
92
DCM- gross
basketball dilation of all four chambers, hypertrophy with increased weight, flabby chamber walls, endocardial thrombi,
93
DCM- microscopically
- combo of hypertrophied and stretched myocytes
| - interstitial fibrosis
94
DCM and toxin exposure
ethanol and some chemotherapeutics
95
pregnancy associated DCM
- occurs in last month of pregnancy or several mos after delivery
- might be related to the increased CO or immunologic factors
- at risk for next pregnancy
96
hemochromatosis associated DCM
- excess iron absorption=cardiac deposition of Fe interferes with oxphos
- seen via hemosiderin deposits
97
complications of DCM
HFrEF, dysrhythmias, MR, embolization from mural thrombi
98
LV noncompaction
- unclassified cardiomyopathy but presents with DCM
- postnatal persistence of embryonic pattern of myoarchitecture (very trabeculated)
- mutation in tafazzin protein
99
takotsubo cardiomyopathy
- "broken heart syndrome"
- catecholamine induced due to emotional stress
- reversible LV apical ballooning
- mimics ACS (looks like a NSTEMI on ECG)
100
what does HCM do to the LVOT?
obstructs it (1/3 of the time)
101
ASH
- asymmetric septal hypertrophy-IV septum disproportionately affected (90% of cases)
- banana shaped ventricular cavity
- fibrous mitral valve scar
102
what obstructs the LVOT in HCM ASH?
- bulging of the IV septum into the tract beneath the aorta
- abnormal movement of the MV leaflet into the tract
-associated with cresecnedo/descrescendo systolic murmur
103
HCM microscopically
disarray of intracellular myofibrils, disarray of myocytes with branching pattern
104
which cardiomyopathy is associated with sudden death in young athletes?
HCM--component of ischemia due to thickened intramyocardial arteries (narrowed)
105
cause of HCM?
100% genetic--sarcomeres
106
treatment for HCM
- myomyectomy
- dual chamber pacemaking
- ETOH septal ablation (literally inducing an MI so cells shrink away after dying--craziness)
107
how can we distinguish HCM from AS quickly? (they both present with the same murmur)
- valsalva and standing will decrease the preload, which in HCM will increase the murmur but decrease it in AS
- squatting will increase the preload, which in HCM will decrease the murmur but increase it in AS
108
RCM-gross
- normal ventricular size, dilated atria
| - very stiff
109
RCM- microscopically
interstitial fibrosis, amyloid deposition
110
types of amyloidosis associated with RCM
Ig light chain derived, soluble amyloid associated protein (from chronic inflammation), transthyretin (elderly)
111
recognize amyloids on imaging
apple green birefringence
112
RCM-doppler
very large v waves, little to no a waves
113
myocarditis
inflammation in the myocardium which initiates myocardial damage due to immune rxns, infections, etc
-usually viral or drug hypersensitivity
114
myocarditis- microscopically
eosinophila, lymphocytes/PMN infiltration
115
myocarditis-gross
dilated, flabby hearts (not hard) that don't weigh much (no extra muscle since it is usually such an acute process)
116
giant cell myocarditis
only affects the heart, with large necrotizing granulomas
