Normal Cardiac Anatomy
Normal Cardiac Anatomy
Anderson Chapter 2 Notes
Heart Within the Chest
-at middle mediastinum, with 2/3 of heart to L of midline
-the base of the heart is the top of the ventricles, apex is the point of the LV
Valve Relationships
-When viewed fr the front, the Pulm Vavle is Sup & Left. The Ao Vlv, MV, TV are more inferior. Ao more R of PA vlv.
-Ao is in the center of the heart, adjacent to the MV & TV, with PA separate, when viewed fr short axis
Pericardium
-Fibrous Pericardium- tough external layer
-Serous Pericardium- a bag within the fibrous pericardium, reflected along the heart wall to form the epicardium
-2 sinuses- Transverse sinus between the GAs and the Oblique sinus surrounding the heart
Mediastinal Nerves
-Vagus & Phrenic nerves course through the fibrous pericardium, on each side
-Phrenic is anterior to lung hilum
-Vagus is posterior to lung hilum
-Recurrent laryngeal nerves - pass around the brachiocephalic trunk on the R side and around the PDA/LA on the L side
Thymus
-anterior/lateral aspect of pericardial sac, at the GA trunks
Cardiac Chambers
-Note that the RA/LA and RV/LV are NOT truly in a R to L relationship. Rather, they are in an ant-post relationship, with RA & RV being anterior to LA and LV.
-only the LAA protrudes to the anterior
-Note that the Ao and MV valves are adjacent to each other at the base of the LV
-PA is separated from the tricuspid valve by a ring of tissue- the crista supraventricularis (aka supraventricular crest)
-this c.s. is adjacent on its posterior aspect to the Ao valve/root
-[ ] ??aka the conus, the ring of tissue below the Pulm Vlv...
-The diaphragmatic surface is made of the RV
-acute margin = sharp angle bn the sternocostal and inferior surface
-obtuse margin = Left border is by the LV- more gentle curve
-makes sense bc LV is a torpedo shape, RV a crescent shape
-Grooves
-AV Groove = Coronary Groove - bn atria and ventricles
-Interventricular Groove
-Cardiac Crux - on inferior (diaph) surface- where the interventric groove joins the AV groove
RIGHT ATRIUM
-Veinous component (Sinus venosus in non-Andersonian speak) - receives the systemic venous return- IVC, SVC, and CS
-Has a "vestibule" = smooth walled area that inserts into the TV
-Septal surface with fossa ovalis
-RA Appendage with extensive trabeculations, extending out from the RAA
-RAA is broad, triangular shaped (Snoopy ear)
-border of RAA and venous part of the RA is marked by the terminal groove externally, and a terminal crest internally
-The pectinate muscles that extend fr the RA extend into a diverticulum, around the AV junction, inferior to the CS orifice
-By Dr. Anderson, the pectinate muscles (trabeculations) are the most constant feature and this the identifying feature for a RA. (**Note that previously he stated the RA Appendage shape itself was the key feature.)
-Eustachian Valve- flap like muscular/fibrous valve extending from the terminal crest (RAA-RA jct) over the IVC
-Thebesian Valve- flap like muscular/fibrous valve extending from the terminal crest (RAA-RA jct) over the CS
-Tendon of Todaro- a continuation of the Eustachian valve, running through the wall between the CS and the FO, to insert into the Ao root. --> border of Koch triangle
Septal Surface
-While the septal wall looks big, really only the floore of the FO and its antero-inferior rim actually divides the two atria.
-The secondary septum (septum secundum) is mainly made because of an infolding of the walls of the atria (most prominantly at the superior aspect) --> folding bn the SVC and the RUPV/RLPV
-The rest of the septum- the antero-inferior part- is made of muscularisation of the atrial or vestibular spine- aka the dorsal mesenchymal protrusion (see ch 3 embryology) [it is a separate protrusion that joins the atrial septum with the ventricular septum at the crux of the heart... per Anderson...
-The TV is usually displaced more apically than the MV, so there is an atrio-ventricular septum between the MV level and the TV level. Here, the inferior AV groove extends to separate the overlapping segments of the atrial and ventricular muscle. aka sinus septum- bc separates the orifice of the CS and the IVC. It is just the adjacent walls of the 2 ventricles (!)
LEFT ATRIUM
-LA Appendage- long and tubular, with several constrictions along its length
-restricted opening to the LA
-pectinate muscles limited to LAA mainly, not by the AV valve (not in the vestibule)
-Vestibule at posterior part of the AV valve is smooth, without trabeculations
-CS is within the AV groove just above the AV valve level
-PVns open into the corners of the smooth walled venous part
-Septal surface is formed by the flap of the oval fossa (foramen ovalis) valve-
RIGHT VENTRICLE
-Inlet, Apical trabecular, and Outlet parts
-Inlet- contains/supports TV leaflets, and extends to the attchmts of the valve's tension apparatus
-TV Leaflets- Septal, Inferior (mural), and Anterosuperior
-Septal leaflet has attchmts to the interventric septum
-Inf leaflet -runs along the diaphragmatic surface of the RV
-Ant-sup leaflet- most extensive leaflet, extends fr the zone of apposition with hte septal leaflet to the acute margin of the ventricle
-Outlet
-relatively smooth walled
-forms a free-standing sleeve of muscle that supports the Pulm vlv = infundibular sleeve aka infundibulum aka conus
-Pulm vlv leaflets are attached in smeilunar fashion within the sleeve - crossing a circular jct bn the ventricular muscle and the fibroelastic wall of the pulm trunk (no clear annulus...)
---> 3 crescents of ventric muscle are incorporated within the bases of the sinuses of the pulm trunk, and three triangular areas of pulm trunk are incorporated within the ventricular outflow tract beneath the tips of the valve leaflets..., --> no true fibrous ring/annulus at the valve leaflets
-the part of the infundibulum that is in between the TV and the pulm vlv is the supraventricular crest (think of it as the internal aspect of the infundibulum that lies bn the 2 valves).
-Anderson stresses that while this part of the infundibulum is often referred to as a septal structure, it really is not. Instead, it is made because of a folding in the RV muscle wall, so he labels this part as the ventriculo-infundibular fold. This is simply the external aspect of the conus in the region between the TV and PV (with supraventric crest being the internal aspect of this part).
-He states that while there is a small part of the septomarginal treabeculation that is a septum bn the RV and LV, it is not a true muscular outlet septum (this is the part immediately within the notch of the Y formed by the septal band.)
LEFT VENTRICLE
-Inlet
-surrounds & supports MV leaflet
-paired pap muscles
-MV
-when the valve is closed, see one line of apposition (unlike TV) --> thus should say MV has 1 commissure
-Mural = posterior leaflet is lengthy, gaurding 2/3 of the valve orifice
-Anterior = Aortic leaflet -has fibrous continuity with the left and non coronary artery leaflets of the Ao vlv, guards only 1/3 of the MV orifice, but is much deeper than the shallow post valve leaflet
-the cords insert into the anterolateral posteriomedial papillary muscles
-no septal insertion of the cords (septophobic), leaving the septal wall of the LVOT open...
-Trabcular portion
-finer and criss-cross treabeculations, often cross the LV cavity , espec fr the paps
-Outlet
-much shorter compared to the RVOT
-Ao vlv leaflets are supported only around the anerior quadrants of the outflow
-postly, 2 of the leaflets of teh Ao vlv are in fibrous cont w the anterior (aortic) MV leaflet (non & L cor artery)
-like w PVlv, the seminlunar atcchmts are invorporated crescents of ventricle.. w three triangles of arterial wall incorped into the LV..., no true annulus
-Anderson prefers to call the non-coronary sinus the non-facing sinus bc rarely one can have a cor artery fr it; he also calls teh other sinuses L and R facing sinuses
-the fibrous triangle bn the L cor leaflet and the Non cor leaflet of the Ao vlv separates the LVOT fr the transversesinus of the pericardium--> forms the wall bn the back of the Ao and the anterior interatrial groove
-the fibrous trangle bn the R cor art leaflet and the non-cor art leaflet is continuous with the membranous septum. If it was removed, it would cause a communication bn the LVOT and the transverse sinus above the inner curvature of the RV, with the pericardial space that is above the supraventricular crest
-the fibrous triangle bn the 2 cor leaflets of Ao vlv separates the LV cavity fr the tissue interposing bn the ant surface of the Ao and the post surface of the freestanding subpulm infundibulum.
ARTERIAL TRUNKS
-MPA spirals around the centrally located Ao and then bifurcates
-Root- cloverleaf shape
-truncal sinuses interdigitate with the supporting ventric structures
-sinotubular junction- just after the sinus, at jct w the tubular trunk of the GA
-Ao runs superiorly, then horizontally to become the transverse arch --> Brachiocephalic, L common carotid, and LSCA arteries
-isthmus = area of Ao bn the LSCA and the PDA/LA
-Thoracic Ao = beyond PDA/LA
-PDA/LA runs fr underside of Ao arch to the upper surface of the LPA
-L recurrent laryngeal nerve turns back into the midastinum around the PDA/LA
HEART VALVES
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Triangle of Koch
-apex - fibrous tissue of the posterior part of the Ao root
-contains the fibrous part of the atrioventricular septum (part of the membranous septum)
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FIBROUS SKELETON
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CONDUCTION TISSUES
-SA nd- comma shaped structure, at the terminal groove- inferior to the crest of the atrial appendage. in 10% ppl, it extends across teh appendage to sit like a horseshoe
-arterial supply- Nodal Artery- fr the R or circumflex cor artery, then runs thru interatrial grove, enters terminal groove across or behind the SVC-RA jct
-in some ppl, it comes fr the lateral part of the RCA or fr the distal course of the circ artery
-then it runsa cross the lateral margin of RAA or across the dome of the LA --> risk at surgery
-Interatrial tracts- narrow, insulated tracts of cells joining the SA nd to the AV nd
-AV Nd - surrounded on most sides by short zones of transitional cells
-within Triangle of Koch
-tendon of Todaro, septal leaflet attchmt of TV, and CS orifice
-arterial supply- courses thru the triangle of Koch in a space bn the atrial musculature and the crest of the interventric septum. It originates fr the dominant cor artery
-SHort segment, then penetrate the central fibrous body as teh bundle of His
-then at the crest of the mscular septum, beneath the non-facing leaflet of the ao vlv (non coronary leaflet), it branches
-LBB- runs down smooth LV septal surfaces and fans out twd apex
-RBB- crosses the septum to emerge beneth the medial pap muscle, then extends within the septomarginal trabeculation, and then divides by the apex. A prominent branch usually passes to the parietal wall via the moderator band
CORONARY VESSELS
-usually one cor art fr two of the 3 sinuses of Valsalva of the Ao. Nearly always these are the ones "facing" (closest to/adjacent to) the PA
-Andersonian approach:
-pretend to stand in the non cor sinus and face the PA.
-at your right hand is the sinus that usually gives rise to the RCA, at the left hand is the sinus that usually gives rise to the LCA. By convention, the R sided one is sinus 1 and the left sided one is sinus 2. =Leiden Convention, works even with malposed GAs...
-RCA arises fr the R hand facing sinus, usually beneath the ST junction, and often w eccentriccally positioned within the sinus
-passes directly into the R AV groove, lying in the curve of the ventricoluinfundibular fold, above the supraventricular crest
-then, give rise to the infundibular and atrial branches.
-then, turn round the acute margin of the RV, and give rise to the acute marginal branch
-the main stem of the RCA continues along the diaph surface of the R AV jct, and gives off more atrial and ventricular branches, until (in 90% of ppl) it gives rise to the inferior interventricular artery (aka posterior artery)
-and then continues to some degree as teh RCA to some part of the diaph surface of the LV
-this is in a R cor artery dominant heart, the most common form
-LCA main stem takes origin fr the L hand facing sinus, and passes to the L AV groove, benath the LAA orifice
-then, branhces into the anterior interventricular (LAD) and the circumflex arteries; may (in 33% ppl) --. an intermediate artery to supply the obtuse marginal surface of the LV
-the anterior interventricular artery - aka anterior descendinga rtery- runds down the anterior interventric groove & --> diagonal branches to the surfaces of the RV and LV, along with perforating arteries that go perpendicular, directly into the ventric septum
-the first septal perforating branch is signif, bc it is just posterior to the subpulmonary infundibulum
-the circumflex artery extent depends on whether RCA is dominant. If RCA is dominant, then the circ stops abruptly after giving off the obtuse marginal branches. In 1/10 of ppl , when the pt is LCA dominant, then the circ runs all the way around the LV jct to continue at the crux to supply the diaph surface of the heart as the inferior (posterior) interventric artery, and also to supply the artery to the AV nd.
Coronary Veins
-major veins run alongside the major arteries
-larges vein = the great cardiac vein- accompanies the anterior interventric artery, turns beneath the LAA to join the coronary sinus
-jct bn the vn and the sinus is the pt of entrance of the oblique vein of the LA = vein of Marshall- which corresponds w the prominent venous valve = the valve of Vieussens
-Coronary Sinus - then runs in L AV groove to the RA. As it enters RA, it collects the middle cardiac vein, which accompanied the inferior/posterior interventric art, adn the small cardiac vn which was in the R AV groove.
-if there is a persistent LSVC, it usually drains to the CS thru a route normally occupied by the oblique vein.
-Thebesian veins- minimal cardiac veins that drain blood fr the walls of the RA and LA, opening directly into the atria.
