Embryology Flashcards
List 3 characterisitics of ASD no amenable to Amplatz device closure
ASD with partially anomalous venous drainage (ie., sinus venosus ASD)
Border of ASD with atrial rim < 4mm
ASD larger then 40 mm (largest device 40 mm)
Name collateral inflow in classic coarctation and outflow
Collateral inflow, proximal to obstruction from subclavian internal thoracic artery throcervival trunk vertebral Collateral outflow superior/inferior epigastric intercostal arteries
What is Cardiac septation?
Process that begins after looping morphogenesis has realigned the cardiac segments so that the right ventricular and left ventricular are located beside one another.
How does the atrial septum form
Atrial septum is made up of septum secundum, septum primum, and contributions from the atrioventricular cushions.
Septum secundum is an infolding in the roof of the common primitive atrium. Septum primum develops from the dorsal of the atrium and grows toward the atrioventricular cushions and closes off the ostium primum when it fuses with the atriovenitrcular cushions.
The septum primum develops fenestrations that coalesce into the ostium secundum
How does Ventricular septum form
Complex structure that involves components from the attrioventricular cushions, the muscular ventricular septum, and the conal septum. After looping the muscular septum is a ridge of myocardium corresponding to the furrow of the primary fold on the outer curvature of the heart. this separates the primitive left and right ventricle.
Muscular septum grows concordantly with the ventricles.
What are basic embroloy principles
Cardivascular system is first functional system in embryo
Blood circulation occurs by 3 weeks
Heart develops 3-8 weeks
Critical period for anomalies is 306 weeks
When is heart development
Endocardial tubes fuse to form heart tube (21 days)
Heart beings to beat (22 days)
Heart folding
D –right L (left) loop
Bulboventricular loop—future ventricles
Bulbus cordis—-conus cordis—RVOT
Truncus arteriosus—-great vessels
How does ASD occur
Ostium secundum—excess resorption of septum primum or inadequate development of septum secundum
Ostium primmum—septum primum fails to fuse with endocardial cusion
How does a VSD form
Malalignment
Muscular defect—resorption of septum
Failure of membranous portion to develop from extension of endocardial cushion to fuse with truncocoal septum
What are aortic arch clinical correlates
1, 2, 5, R6 all disapear
3—-carotids
4—mid arch
6–Right Pulmonary artery and ductus arteriosus
What is embrology of Tetralogy of Fallot
Unequal division of conus cordis
Name 3 fetal circulation shunts
Ductus Venosus—becomes the Ligamentum teres, venosum
Foramen Ovale—fossal ovalis
Ductus arteriosus—Ligamentum arteriosus
Shunts close after birth and become ligamentous
How is Foramen Ovale created
Derived from perforation that developed in septum primum as it fused with the endocardial cushions
What is secundum
Septum secundom is a RA ingrowth that is thicker and grows like a flap valve over septum primum in utero (non-obstructive
What type of congenital cardiac pathology causes cyanosis
Right to left shunt
How does a L to R shunt manifest in childhood
Failure to thrive
increased HR
increase RR
Hepatomegaly (1st sign in children)
List acyanotic congenital heart disease with increase pulmonary flow
VSD
PDA
ASD
List acynanotic congenital heart disease with normal pulmonary flow
Pulmonary stenosis
Mitral stenosis
Aortic stenosus
Coarctation of aorta
List cyanotic congenital heart disease with increased pulmonary flow
TGA (transposition of great vessels
TAPVR (total anomalous pulmonary venous return)
List cyanotic congenital heart disease with normal pulmonary flow
Pulmonary stenosis
Tetralogy of Fallot
ASD-Eisenmengers syndrom
What is Eisenmengers syndrome
Shift from a previous left to right shunt that now become a right to left shunt.
This represents a sign of increase pulmonary vascular resistance and pulmonary hypertension that maybe irresversible
What is a squatting action performed by an infant
a strategy to decrease the right to left shunting by increasing the systemic vascular resistance
When do most VSD close
6 months of age
When a VSD is going to cause a problem what is usually the age
usually 4 to 6 months of age
What are signs of heart failure in infants with large VSD
Tachypnea
Heptaomegaly
Poor feeding and failure to thrive
Management of VSD is dependent on what factors
size of defect
type of defect
shunt volume
PVR
What are indications of surgical repair of VSD
Infants with severe CHF, FFT, or respiratory infections in first 3 months
Outlet VSD–risk of developing aortic insufficiency or regurgitation
If closure is not achieved spontaneously by school age
if PVR is > 4 to 6 Woods units
What is a contraindication to surgical repair of VSD
PVR > 8 to 10 Woods units–use a vasodilator to see if it is reversible; if so repair
What are potential surgical complications from closure of VSD
Mortality is 1%
Injury to conduction tissue
Injury to tricuspid or aortic valve
transient or permanent heart block < 1%
When should you fix an ASD
When ratio of pulmonary to system blood flow (Qp/Qs > 2)
signs of CHF, fatigue, SOB, exercise intolerance, recurrent respiratory infections
What are classical findings in pts with ASD
Fixed splitting of the 2nd heart sound
Systolic ejection murmur @ LUSB (due to “relative: pulmonary stenosis = increased flow across a normal pulmonary valve.
What are indications for ASD repair
Large or symptomatic defects
Asymptomatic with Qp/QS > 1.5
If closure not achieved by school age
All ostium primum AVSD need repair
What is medical management of TOF
oxygen narcotics correction of acidosis transfusion (for anemic infants) alpha-agonists (increase SVR0 beta-blockers (to suppress the incidence of spells
What are the treatment options for hypoplastic left heart syndrom
Heart transplant Norwood procedure Atrial septectomy Anastomosis of proximal PA to the aorta with homograft augmentation of the aortic arch Aortopulmonary shunt or RV to PA conduit
For the Fontane procedure to be successful what criteria must be met
Normal PA pressure (< 20 mmHg) Normal PVR (< 2 woods units)
What was Fontan procedure intially designed for
Tricuspid atresia
What was initial Fontan procedure
It was called an Atriopulmonary connection (AP)
This consisted of the right atrial chamber being isolated by the closure of the ASD and the hypoplastic tricuspid valve.
Then the right atrial appendage was anastomosed to the right pulmonary artery.
What two modifications to the fontan procedure have occured
Lateral Tunnel technique–whereby the right atrium was baffled with an intraatrial patch and the superior vena cava was sutured directly to the right pulmonary artery
Exatra-cardiac shunt from the inferior vencava to the right pulmonary artery
Describe development of heart
“The heart develops from the splanchnopleuric mesoderm lying immediately cranial to the prochordal plate (also called the “cardiogenic” area). The two cardiogenic areas on either side of the primitive streak have intrinsic differential growth characteristics and are the determinants of sidedness, which is the first fundamental choice the primitive heart makes (situs solitus or situs inversus).”
Excerpt From: Carlos M. Mery & Joseph W. Turek. “TSRA Review of Cardiothoracic Surgery.” Feedbooks, 2011. iBooks.
This material may be protected by copyright.
What is development of outflow tract
“The distal part of the bulbus cordis (called the truncus arteriosus) gives rise to the great arteries.”
Excerpt From: Carlos M. Mery & Joseph W. Turek. “TSRA Review of Cardiothoracic Surgery.” Feedbooks, 2011. iBooks.
This material may be protected by copyright.
Describe pulmonary vascular resistnace development
“At birth, the pulmonary resistance is 8 Wood units/m2, drops to the normal level of 2 Wood units/m2 at about 8 weeks. A pulmonary/systemic vascular resistance ratio of less than 0.2:1 is considered normal. With the expansion of the lungs at birth, the dilation of the existing pulmonary arteries along with the development of new arteries/arterioles follows, contributing to the drop in PVR”
Excerpt From: Carlos M. Mery & Joseph W. Turek. “TSRA Review of Cardiothoracic Surgery.” Feedbooks, 2011. iBooks.
This material may be protected by copyright.
What are indications for pa banding
“Swiss-cheese” muscular ventricular septal defects
Single ventricle physiology with increased pulmonary blood flow in preparation for future Fontan procedure (i.e., tricuspid atresia type IIc)
To prepare and retrain the ventricle in patients with transposition of the great arteries for future arterial switch procedure”
Excerpt From: Carlos M. Mery & Joseph W. Turek. “TSRA Review of Cardiothoracic Surgery.” Feedbooks, 2011. iBooks.
This material may be protected by copyright.
How do you calculate size of band to,place around PA
“Trusler’s rule can be used to guide the initial circumference of the band. For simple defects (VSD, tetralogy of Fallot), use the following rule: 20 mm + 1 mm for each kg body weight. For mixing defects (single ventricle, transposition), use the following rule: 24 mm + 1 mm for each kg body weight.”
Excerpt From: Carlos M. Mery & Joseph W. Turek. “TSRA Review of Cardiothoracic Surgery.” Feedbooks, 2011. iBooks.
This material may be protected by copyright.
Define lesions of complete av canal defect
“A complete AV canal defect (CAVC) consists of a primum ASD, an unrestrictive inlet VSD, and a common AVV. There are three types of CAVC”
Excerpt From: Carlos M. Mery & Joseph W. Turek. “TSRA Review of Cardiothoracic Surgery.” Feedbooks, 2011. iBooks.
This material may be protected by copyright.
Define each of the 3 types of av canal defects
“Rastelli A (75%). Defined by a complete division of the superior common leaflet over the septal crest with chords attaching the right and left portions of this leaflet to the appropriate side of the septum. In this type, the VSD is often small.”
Excerpt From: Carlos M. Mery & Joseph W. Turek. “TSRA Review of Cardiothoracic Surgery.” Feedbooks, 2011. iBooks.
This material may be protected by copyright.
Describe other type
“Rastelli B. Rare and almost never seen with balanced ventricles. Straddling chords extend from the TV component into the LV (usually in cases of LV dominance) or from the MV component into the RV (usually in cases of RV dominance). Rastelli C (25%). undivided superior common leaflet, usually without any chordal attachment of the central part of the leaflet to the septum. most often associated with tetralogy of Fallot.”
List types of tricuspid atresia
“Type I. Normal anatomy (approximately 70%)
A: pulmonary atresia with almost nonexistent RV
B: pulmonary stenosis with small VSD
C: large VSD, pulmonary stenosis
Type II. d-transposition of great arteries (TGA) (approximately 30%)
A: pulmonary atresia
B: pulmonary/subpulmonary stenosis
C: normal/enlarged pulmonary valve and artery with no stenosis
Type III. l-TGA
What physiological problem of tricuspid atresia
“no communication between the RA and RV. As such, a right-to-left shunt exists for the circulation of blood. The degree of obstruction to pulmonary blood flow, the relationship of the great arteries, and the restrictiveness of the VSD determine the exact pathophysiology and clinical sequelae of tricuspid atresia.”
Excerpt From: Carlos M. Mery & Joseph W. Turek. “TSRA Review of Cardiothoracic Surgery.” Feedbooks, 2011. iBooks.
This material may be protected by copyright.
What’s surgery for tricuspid atresia
“staged procedures culminating in a final single ventricle physiology:
Systemic to pulmonary shunt: classic Blalock-Taussig shunt (subclavian to PA) or modified Blalock-Taussig shunt (graft from innominate artery to PA).
Cavopulmonary anastomosis (Glenn shunt vs. hemi-Fontan shunt).
Fontan procedure for complete separation of systemic and pulmonary blood circulation (lateral tunnel vs. extracardiac conduit).”
Excerpt From: Carlos M. Mery & Joseph W. Turek. “TSRA Review of Cardiothoracic Surgery.” Feedbooks, 2011. iBooks.
This material may be protected by copyright.
What is classification of Ebsteins anomaly
“Type A: Adequate-sized RV
Type B: Large atrialized RV but with free movement of the anterior leaflet
Type C: Large atrialized RV and severely restricted movement of the anterior leaflet which may cause significant RVOT obstruction
Type D: Almost complete atrialization of the RV with the only communication between the atrialized ventricle and the infundibulum (functional RV) being through the anteroseptal commissure of the valve”
What is noncomitted DORV
“Non-committed
VSD is positioned remote from the conal septum or aortic valve
Also includes midmuscular and apical muscular VSDs”
Excerpt From: Carlos M. Mery & Joseph W. Turek. “TSRA Review of Cardiothoracic Surgery.” Feedbooks, 2011. iBooks.
This material may be protected by copyright.
Describe subaortic vsd
“Subaortic
The VSD is positioned below the aortic valve
No subaortic conus
Superior margin of VSD is the aortic annulus
Blood from the LV flows through the VSD to the aorta and blood from the RV flows mainly to the PA”
What is subpulmonary DORV
“Doubly-committed
VSD is positioned nearly equally below the aortic and pulmonary valves
Blood from both ventricles is substantially mixed in the RV, yielding physiology that resembles a large VSD”
How do hypoplastic left hearts survive
“Left-to-right shunting at the atrial level allows pulmonary venous return to enter the RA, and right-to-left shunting through an enlarged PDA allows for systemic perfusion. Retrograde flow to the arch and ascending aorta provides cerebral and coronary blood flow.”
“Four morphologic subtypes of HLHS can be defined based on the status of the left-sided heart valves:”
“Aortic and mitral atresia (AA/MA)”
“Aortic atresia and mitral stenosis (AA/MS)
Aortic stenosis and mitral atresia (AS/MA)
Aortic and mitral stenosis (AS/MS)
AA/MA is the most common, AS/MA is the least common, and AA/MS is the highest-risk subtype.”
What is stage 1 Norwood
“Stage I reconstruction is performed shortly after birth via median sternotomy and deep hypothermic circulatory arrest (DHCA)”
- atrial septectomy
- Construction of a neoaorta from the pulmonary valve by division of the PA at the bifurcation and anastomosis of the aorta to the proximal PA
- Placement of a systemic-to-pulmonary modified Blalock-Taussig shunt (mBTS) or RV to PA conduit
What is stage II Norwood
The second stage procedure (hemi-Fontan or bidirectional Glenn) is performed between 2 and 6 months of age and aims to reduce the volume load on the RV once PVR has fallen sufficiently to accommodate passive venous return into the pulmonary circulation. The systemic and pulmonary circulations are partially divided by performing a bidirectional cavopulmonary anastomosis. The SVC is divided and anastomosed end-to-side to the right PA.”
What is stage III Norwood
“The Fontan operation is performed at 2 to 4 years of age and entails redirecting IVC flow to the PA/SVC confluence to complete the division of the pulmonary and systemic circulations. The RV is relieved of systemic venous return allowing for pressure and volume offloading of the ventricle and improved oxygenation from abolishment of right-to-left shunting. The two common techniques for Fontan construction are the lateral atrial tunnel or the extracardiac interposition graft.”
What is stage III Norwood
“The Fontan operation is performed at 2 to 4 years of age and entails redirecting IVC flow to the PA/SVC confluence to complete the division of the pulmonary and systemic circulations. The RV is relieved of systemic venous return allowing for pressure and volume offloading of the ventricle and improved oxygenation from abolishment of right-to-left shunting. The two common techniques for Fontan construction are the lateral atrial tunnel or the extracardiac interposition graft.”
What is Embrological development of arch
“The third arches form the carotid arteries. The left fourth arch normally forms the distal aortic arch and aortic isthmus from the origin of the left common carotid (LCC) to the descending TA”
Excerpt From: Carlos M. Mery & Joseph W. Turek. “TSRA Review of Cardiothoracic Surgery.” Feedbooks, 2011. iBooks.
This material may be protected by copyright.
What is a PA sling
“A PA sling is the name for a vascular ring formed around the trachea when the left PA passes over it from an anomalous origin off the right PA, associated with respiratory symptoms.”
Excerpt From: Carlos M. Mery & Joseph W. Turek. “TSRA Review of Cardiothoracic Surgery.” Feedbooks, 2011. iBooks.
This material may be protected by copyright.
What is treatment for vascular rings
“For vascular rings, surgical division is indicated when symptomatic and may be deferred in asymptomatic patients. Good nutritional status and respiratory care should be ensured preoperatively. Unless there is a patent segment of a double arch that is more than 2 to 3 cm in diameter, the procedure of choice is thoracoscopic ring division. Open, it is performed via a fourth interspace thoracotomy”
Excerpt From: Carlos M. Mery & Joseph W. Turek. “TSRA Review of Cardiothoracic Surgery.” Feedbooks, 2011. iBooks.
This material may be protected by copyright.
What is development of vascular rings
“The great majority (approximately 95%) of rings have a dominant (larger) right aortic arch (RAA) with ring formation on the left. Therefore surgical division of rings is nearly always performed through a left thoracotomy.”
Excerpt From: Carlos M. Mery & Joseph W. Turek. “TSRA Review of Cardiothoracic Surgery.” Feedbooks, 2011. iBooks.
This material may be protected by copyright.
What is dks procedure
Damus-Kaye-Stansel procedure, entails anastomosis of the proximal end of the transected main pulmonary artery to the ascending aorta and a shunt to establish pulmonary blood flow.
What are classic features of ARDS
the definition for ARDS by having the characteristic triad of radiographic changes, hypoxemia, and decreased lung compliance.
What is pulsus paradox
pulsus paradoxus, an exaggerated decrease of the systolic blood pressure with inspiration. Ordinarily, blood pressure decreases up to 10mmHg with inspiration in a spontaneously breathing patient. In pulsus paradoxus, this decrease in systolic blood pressure is >20 mmHg without a corresponding decrease in diastolic blood pressure (see figure).
Explain how the heart is formed
The heart tube forms from fusion of the two ventral aorta which orginate from the mesodermal layer of the yolk sac.
Following longitudinal growth and rotation of the heart tube, it divides into 3 regions
1) Conus truncus 2) Sinus venosus 3) Bulbis cordis
Endocardial cushions from the partition between atrai and ventricles within the heart tube to create atrioventricular canals and eventually the mitral and tricuspid valve.
The atrial septum forms from the septum primum and septim secundum, leaving a small opening, the foremen ovale.
The muscular part of the interventricular septum forms the ventricular myocardium of both ventricles, whereas the membranous part originates from fusionof the endocardial cushions and the desecending truncal cushions.
