CARDIAC Flashcards
EMBRIOLOGY
Heart Tub: formation
- week 3
- splanchnic mesoderm (cardiogenic area) + neural crest cells = cardiogenic cells
- cardiogenic cells → pair of primordial heart tubes → heart tube (single)
EMBRIOLOGY
Heart Tub: development
dextral looping + rotation
- truncus arteriosus grows more → down + ventral movimentation to the right
- atria + sinus venosus → up + dorsal movimentation to the left
EMBRIOLOGY
Heart Tub: dilatations
EMBRIOLOGY
Fetal Circulation: 3 major venous systems
- Vitelline
- deoxygenated blood
- from yolk sac
- will form veins of the liver and part of inferior vena cava
- Umbilical
- oxygenated blood
- from placenta
- Cardinal
- deoxygenated blood
- from fetal body
- will form some of the major veins (cavas, azygo etc)
EMBRIOLOGY
Fetal Circulation: 3 shunts
umbilical vein → bypass lung and liver (shunts)
- Ductus Venous - bypass sinusoids of the liver
- Foramen Ovale bypass pulmonary circulation (right atrium to left atrium into systemic circulation)
- Ductus Arteriosus bypass pulmonary circulation (deoxygenated blood from pulmonary trunk to aorta)
EMBRIOLOGY
The shunting of blood through foramen ovale and ductus arteriosus occurs because of right-to-left pressure gradient.
TRUE OR FALSE
TRUE
EMBRIOLOGY
Pressure Gradients: Fetal vs Postnatal
Postnatal changes
- umbilical vein closes
- less pressure to right atrium
- lungs expansion
- increase venous return to left atrium
- increase flow to pulmonary circulation
EMBRIOLOGY
Fetal Circulation: Closure of the shunts
Foramen Ovale
(left atrium >> right atrium)
Ductus Venous
(increase oxygen tensios + smooth muscles contration + after several hours)
Ductus Arteriosus
(same as ductus venous + bradykinin release + immediated drop of prostaglandin E)
EMBRIOLOGY
Fetal Circulation: Adult Vestiges
EMBRIOLOGY
Heart Tub: Septation
commom chamber
→
right and left horns
(ventricular, atrial and truncus venous - except sinus venous)
→
septation
(week 4 - week 8)
EMBRIOLOGY
Atrial Septation
2 septa
(septum primum and secundum)
+
2 foramina
(foramen primum and secundum)
EMBRIOLOGY
Atrial Septation: Septum Primum + Foramen Primum
- Septum Primum
- grows inferiorly (from the roof)
- doesn’t fuse with endocardial cushions
- Foramen Primum
- betweem septum primum and endocardial cushions
- closed when septum primum later fuses with endocardial cushions
EMBRIOLOGY
Atrial Septation: Septum Secundum and Foramen Secundum
- Septum Secundum
- after foramen primum closes
- from the roof
- right of the septum secundum
- Foramen Secundum
- from the upper part of septum primum
- after foramen primum closes
EMBRIOLOGY
Foramen Ovale is the opening between septum secundum and septum primum
TRUE
EMBRIOLOGY
Endocardial Cushions receives the migrate cells from neural crest in order to form …
atrioventricular valves
+
membranous part of the intervertricular septum
+
aorticopulmonary septum
EMBRIOLOGY
Clinical Correlate: postnatal shunts
right-to-left shunts = cyanotic
left-to-right shuts = non-cyanotic
EMBRIOLOGY
Clinical Correlate: Atrial Septal Defect
female >> male
left-to-right shunt = non-cyanotic
primum vs secundum
EMBRIOLOGY
Clinical Correlate: Secundum Atrial Septal Defect
most commom ASD
excessive resorption of septum primum + underdevelopment of septum secundum
central part of septum
small
symptons at 30
EMBRIOLOGY
Clinical Correlate: Primum Atrial Septal Defect
less commom ASD
failure fusion between septum primum and endocardial cushion
lower atrial septum
may be associated with defects of endocardial cushion (valves)
EMBRIOLOGY
Ventricular Septation
- week 4 - week 7 (usually completed)
- close completely - without shunting
- muscular component
- large + most of the septum
- from the floor of the ventricule (ascends)
- leaving the IV foramen
- membranous component
- thin + superior part of the septum
- closes the IV foramen
- from the fusion of right and left conotruncal rigdes + endocardial cushions
EMBRIOLOGY
Clinical Correlate: Ventricular Septum Defect
MOST COMMON CONGENITAL HEART DEFECT]
- membranous VSD is the most commom
- neural crest cells migration failure
- IV foramen = left-to-right shunt = non-cyanotic
- excessive fatigue upon exercise
- pulmonary hypertension
- ultimately: pulmonary resistence is higher than systemic resistence (Eisenmenger Complex)
- shunt becomes right-to-left = cyanotic
EMBRIOLOGY
Septation of the Truncus Arteriosus
- week 8
- neural crest cells migration
- fusion of conotruncal and bulbar ridges
- spiral fashion
- formation of aorticopulmonary septum
EMBRIOLOGY
Clinical Correlate: Patent Ductus Arteriosus
- left-to-right shunt
- aorta >> pulmonary trunk
- non-cyanotic
- machine-like murmur
- ductus arteriosus fails to close after birth
- low oxygen tension
- prostaglandin E
- premature infants + maternal rubella infection
- prostaglandin can be used to keep the patency in transposition of great vessels
- treatment
- indomethacin (and others prostaglandin E inhibitors)
- acetylcholine
- histamine
- catecholamine
EMBRIOLOGY
Clinical Correlate: non-cyanotic congenital defects
left-to-right shunting
- ASD
- VSD
- Patent Ductus Arteriosus
EMBRIOLOGY
Clinical Correlate: cyanotic congenital heart defects
right-to-left shunting
- Tetralogy of Fallot
- Transposition of Great Vessels
- Persistent Truncus Arteriosus
EMBRIOLOGY
Clinical Correlate: Tetralogy of Fallot (4 major defects)
pulmonary stenosis (most important)
+
membranous IV septal defect
+
right ventricle hypertrophy (secundary)
+
overriding aorta (receives blood from both ventricles)
EMBRIOLOGY
Clinical Correlate: Tetralogy of Fallot (clinical informations)
- most commom cyanotic congenital heart defect
- aorticopulmonary septum fails to close
- right-to-left shunting = cyanotic
- boot-shaped heart = enlarged right ventricle
EMBRIOLOGY
Clinical Correlate: Transposition of the Great Vessels
- failure of the spiral fashion (aorticopulmonary septum)
- right-to-left shunt = cyanotic
- the most common cause of severe cyanosis immediately after birth
- results in 2 closed circulation loops → usually associated with other defects (mixed blood) in order to survive
EMBRIOLOGY
Clinical Correlate: Persistent Truncus Arteriosus
- partial development of the aorticopulmonary septum
- right-to-left shunt
- cyanotic
- truncus arteriosus receives blood from both ventricles
- Always accompanied by membranous VSD
HISTOLOGY
Cardiac Muscle Cells
striated in the same manner as skeletal muscle cells, except…
smaller cells (fibers)
only 1 or 2 nuclei per fiber
nuclei → centrally
less well developt T-tubule system
HISTOLOGY
Layers of the Heart Wall
Epicardium
(outer)
Myocardium
(middle)
Endocardium
(inner)
HISTOLOGY
Composition the Epicardium
- Pericardium
- visceral layer of the serous pericardium
- simple squamous epithelium (mesothelium)
- Connective Tissue
- fat cells
- coronary vessels
HISTOLOGY
Composition of the Myocardium
muscular wall
+
cardiac muscle cells
HISTOLOGY
Endothelium
(simple squamous epithelium)
+
Connective Tissue
HISTOLOGY
Intercalated Disc
special junctions complex between myocardial cells
- gap junctions + adhering junctions
- gap ⇒ eletrical
- adhering ⇒ mechanical
- dark and transverse lines
HISTOLOGY
Purkinje Cells
- modified cardiac muscle cells
- fewer contratile filaments
- large content of glycogen
- eletrical impulse conduction
- run along → cardiac conduction system + endothelial surface
ANATOMY
Heart: External Features
obliquely in the middle mediatinum
+
posteriorly to sternum
+
3 main sulci
(coronary + anterior and posterior interventricular)
ANATOMY
Borders of the Heart
- Right Border → right atrium
- Left Border → left ventricle
- Superior Border → auricules (right and left) + conus arteriosus (right ventricle)
- Inferior Border → right ventricle + apex (left ventricle)
ANATOMY
Surfaces of the Heart
- Anterior (sternocostal) → right ventricle
- Posterior → left atrium
- Diaphragmatic → left ventricle
ANATOMY
Heart: Projections
ANATOMY
Heart: right atrium
- auricle → fetal atrium (pectinate muscles)
- sinus venarum → from sinus venosus (smooth)
- crista terminales → vertical ridge (separation of smooth and rough) + SA node (upper part)
- fossa ovalis → from foramen ovale closure
- tricuspide valve
ANATOMY
Heart: left atrium
- 4 openings
- bicuspid valve (mitral)
ANATOMY
Heart: right ventricle
- trabeculae carneae → myocardium rigdes
- papillary muscle + chordae tendineae
- infundibulum → pulmonary trunk (smooth part)
- septomarginal trabecula (moderator band)
ANATOMY
Heart: left ventricle
- trabecula carneae
- papillary muscles (2) + chordael tendineae
- aortic vestibule
ANATOMY
Heart: Auscultation
ANATOMY
Clinical Correlate: Heart Murmurs
stenosis - orthograde direction
insufficiency - retrograde direction
+
aortic and mitral valves are more commonly involved with heart diseases
ANATOMY
Arterial Supply of the Heart
blood flow enters coronary ateries during diastole
- Right Coronary →
- SA nodal artery (first branch)
- AV nodal artery (distal end)
- marginal artery
- posterior interventricular artery
- Left Coronary
- anterior interventricular or left anterior descending (diagonal artery)
- circumflex artery (marginal branch)
ANATOMY
Interventricular Arteries: posterior vs anterior
Posterior Interventricular Artery
(right and left ventricles + posterior third of interventricular septum)
Anterior Interventricular Artery
(anterior 2/3 of interventricular septum + left ventricle + bundle of His + Apex)
ANATOMY
Clinical Correlate: Obstruction in Myocardial Infarction
Left Anterior Descending - 50%
Right Coronary - 30%
Circumflex Artery - 20%
ANATOMY
Venous Drainage of the Heart
- Coronary Sinus → from left sinus venosus (fetal) + lies in the posterior coronary sulcus + opening in the right atrium
- Great Cardiac Vein → main tributary of the coronary sinus + lies in the anterior interventricular sulcus
- Middle Cardiac Vein → lies in the posterior interventricular sulcus
- Small Cardiac Vein → lies in the coronary sulcus (right)
- Venae Cordis Minimae (thebesiam veins) + Anterior Cardiac Veins → opening directly to the chambers
ANATOMY
Cardiac Conduction System
- SA node
- pacemaker
- crista terminalis (upper part)
- arterial supply - right coronary
- AV node
- interatrial septum (near to the opening of coronary sinus)
- arterial supply - right coronary
- Bundle of HIS
- LAD artery supplies
- right ventricle - moderator band
ANATOMY
Cardiac Innervation
SANS
increase heart rate + pain in ischemia (T1-T5)
PANS
decrease heart rate + cardiac reflexes
