Situs and Position/hemodynamics Flashcards
Atrial situs refers to the
location /position of the atria and abdominal organs
“Atrial situs solitus” the arrangement is
right sided atrium
right sided trilobed lung
right side liver and gallbladder
left side stomach bubble, spleen, AO
Levocardia apex point to the left
“Atrial situs inverses” the arrangement is
Atria are transposed “mirror image”
left side systemic atrium
left sided trilobed lung and liver
right-sided stomach and Aorta
cardiac apex pointed rightward
“Situs ambiguous” describes
everything in-between
Heterotaxy
Means different arrangement,
maybe right or left isomerism
Situs ambiguous with right isomerism
referred to asplenia or double right-sidedness
bilateral trilobed lungs
bilateral right atria
no spleen
bilateral SVC
absent coronary sinus
TAPVR
intact IVC
midline liver
Situs totalis
refers to situs inversus totallis which means complete mirror image of all major organs in the chest and abdomen
How are the left and right atria best distinguished apart from one another?
by their appendage.
-Right atria appendage is broad base triangle shape
-left atria appendage is narrow and finger like
Situs ambiguous with left isomerism
Bilateral left sidedness
* Bilateral left atrial appendages
* Bilateral bilobed lungs
* polyspleens
* Interruption of the IVC with azygos continuation
* Ipsilateral pulmonary veins
* Persistent LSVC
Absent Sinus node
atrioventricular septal defect
pulmonary outflow obstruction
congenital complete heart block
situs ambiguous with left isomerism is referred as
Polysplenia
situs ambiguous with right isomerism is referred as
asplenia
Azygos Vein
present during interrupted IVC.
-runs parallel to the AO
-takes flow back to the SVC
Right atria with right isomerism
Bilateral right sidedness
* Bilateral RA appendage
* Persistent LSVC
* Hepatic veins drain directly into atria
* Absent (unroofed) coronary sinus
* TAPVR
* Bilateral trilobed lungs
* Usually absent spleen
-Unbalanced AVSD- right dominate (think DORV)
-pulmonary outflow obstruction/ atresia
-ventricle - arterial connection abnormalities (DTGA)
Vertical Vein
connection between pulmonary veins to the innominate vein to SVC
What does septophobi and septophilic mean?
TV is septophilic, likes the septum
MV is septophobic needs to attach to the papillary muscle “phobia of septum”
Scimitar Vein
connects one or both of the right pulmonary veins to the IVC in the presence of PAPVR
Infracardiac PAPVR
What are the 3 types of viscero-atrial situs?
- solitus-normal
- inversus- mirror image
- Ambiguous- often associated with splenic syndromes and cardiac isomerism
look at stomach bubble and liver, visceral(abdominal) situs and atrial situs are nearly always the same
Great vessel relations
name 5 types
- solitus- normal relation
- inverted- mirror image but normally related
- D-malposed- aortic valve lies to the right of PV (D-TGA)
- L-malposed- aortic valve lies to the left of the PV (L-TGA)
- A-malposed- aortic valve is directly anterior to the PV
The four potential relationships between the great arteries (i.e. aorta [AO] and pulmonary artery [PA]). A) Solitus relationship (usual or normal relationship) is present when the aortic valve is posterior and to the right of the pulmonary artery. B) Inversus relationship is where the aortic valve is posterior and to the left of the pulmonary valve (mirror-image of the usual or normal arrangement). C) Complete transposition (d-transposition) is present when the aortic valve is anterior and to the right of the pulmonary valve. D) Congenitally-corrected transposition (l-transposition) is present when the aortic valve is anterior and to the left of the pulmonary valve.
Normal relation heart would be as follows
Abbreviations
S,D,S
Inverted normal heart segment abbreviation is
I,L,I
Cardiac position needs to clarify two points
- Where is the heart located in the chest cavity?
- Which direction does the apex of the heart point?
Levocardia
heart is in the left chest with apex pointed leftward and anteriorly and inferiorly
normal postion
Dextrocardia
the heart is in the right chest with the apex pointing to the right
dextroposition
Heart is in the right chest with the apex pointing leftward
Can cause hypoplastic right lung
mesocardia
midline position of the heart
(apex still slightly pointed to the left but is shifted more midline)
Label the photo below
normal visceral(abdominal) situs
How much of the heart mass lies to the right of the midline of the chest?
1/3
What are the four sections of the mediastinum?
- Anterior mediastinum
- Posterior mediastinum
- middle mediastinum
- Superior mediastinum
What is the anterior mediastinum
- Borders sternum and ribs
- Includes fascia, lymph nodes, and vessels
What is the Posterior mediastinum
- Border vertebral column
- Contains the thoracic DAO, trachea, and esophagus
What is the middle mediastinum
contains the heart, pericardium, and proximal origins of great vessels
What is the superior mediastinum
Bordered by the 1st ribs
contains aortic arch
Atrial contractions contributes to __ % of ventricle filling?
20%
atrial contraction correlates with ___ wave on the EKG
P wave
atrial depolarization
IVRT time begins with the ___ of the semilunar valves?
closure
proceeds ventricle “relaxation”
IVRT time is affected by?
preload (left atrial pressure)
Age (increases with age)
IVCT time begins with the ___ of the atrioventricular valves?
closure of mitral and tricuspid valve
proceeds Ventricle “contraction”
IVCT time is affected by?
afterload dependent
Afterload
refers to the pressure that the heart must work against to eject blood during ventricular contraction, essentially the resistance the heart faces when trying to pump blood out
Preload
refers to the amount of stretch placed on the cardiac muscle fibers just before contraction, essentially representing the volume of blood filling the ventricle at the end of diastole
Heart defects that significantly affect preload include
MS
MR
AI
Heart defects that significantly affect afterload include
AS
Starlings law
what enters the heart must leave the heart
Ohm’s law
flow is dependent upon pressure and resistance
What is normal pulmonary venous pressure?
mean of 2mmHg
Only veins in the body to carry O2 blood are
Pulmonary veins
Of the branch pulmonary arteries which is longer and what is it course
RIGHT
travels below the aortic arch, posterior to SVC, across the roof of the LA to the lungs
Normal pulmonary artery pressure is
25/10mmHg
mean of 15
The only arteries to carry deoxygenated blood in the body are
pulmonary arteries
Systemic blood can be divided into
low-pressure venous return
and high-pressure arterial output
Systemic venous return refers to
IVC and SVC
coronary sinus
How is the SVC formed
right and left innominate veins
innominate veins are formed by same side subclavian vein and jugular vein
left side longer
azygous vein receives blood from the___
What does it drain into and what appearance does it give?
thoracic and abdominal walls and drains into the SVC
give the appearance of a “shepherds crook”
Systemic venous pressure is normally
SVC/IVC, think what RA chamber pressures are
6mmHg
mean of 6mmHg
Systemic arterial pressures are
think of normal BP and AO pressures
120/80mmHg
LA pressure is
10mmHg
LV pressure
and Ao pressures are?
LV- 120/70mmHg
AO- 120/80mmHg
RA pressures
5mmHg
RV pressures
and PA pressures are
RV 25/5mmHg
PA 25/10mmHg
Oxygen saturation in the left heart is?
Oxygen saturation in the right heart is?
Left- 95%
right- 75%
MS and TS can result in ___ preload due to ___
decrease preload and cardiac output due to reduced ventricle filling during diastole
MS- not as much flow getting to the LV
semilunar valve stenosis will result in ___ afterload
increased afterload
Flow can’t get out so therefore at the end of contraction there is more vol remaining in the LV
TR and MR causes the afterload to ___
decrease
at the end of contraction there is less vol in the LV/RV because TR/MR happens during systole and will reduce the afterload at the end of contraction
AI and PI cause the preload to ___
increase
Moderate VSD will affect what chamber
Left sided volume overload (LVE)
Large VSD blood flow direction will be ___ during early systole and ___ during end systole.
Left to right
right to left
Large PDA’s will have an affect on the ___ side of the heart
left side
there will be an increase in pulmonary venous return to the left side
The ability of the heart to alter force of the ventricular contraction in response to increased ventricle volume is?
Frank-Starling relationship
Fractional area
change in LV area during systole
obtained in PSAX
naormal value 64%
+or- 16%
Definition of fractional shortening
Normal values?
% of change in LV cavity dimensions from systole to diastole
nml= 25-46%
stroke volume
amount of blood pumped in a single cycle
30-60mL
Cardiac output
amount of blood pumped per minute
4-8 L/min
Normal values for delta pressure/delta time
dP/dt
1000mmHg
Normal values for IVRT
60-80msec
diastolic measurement
end systolic measurements occur at the
end diastolic measurements occur at the
Systolic: T-wave
Diastolic: onset of the QRS
Continuity equation
AVA=(0.785xLVOT^2)(VTI LVOT)
________
(VTI AV)
CSA= 0.785 x d^2
stroke volume
Normal QP/QS
ratio of 1
abnormal >1.5
Bernoulli equation
4V^2
determine preassure gradient across valves and shunts
