Cardiac Anatomy And Physiology Flashcards
AV Annulus
Where valve cusps attach to aortic root
Commissures
Where adjacent cusps meet
Lambl’s Excrescences
Small mobile filaments arising from edge of ventricular surface of cusp of AV
No clinical significance–do NOT confuse with vegetation or papillary fibroelastoma
Nodule of Arantius
Small nodule at centre of cusp of AV - more prominent in older patients
Coronary Sinuses
RCC = RCA
LCC = LCA
NCC
MV Leaflets
Anterior and Posterior Leaflets
A1-A3 and P1-P3 (Antero lateral Commissure A\P 1 - Posteromedial Commissure A\P3)
Anterior leaflet almost touches IVS
Function of Chordae Tendinae
chordae keep the mitral leaflets under tension during systole, preventing prolapse of the leaflets back into the LA.
2 Papillary Muscles
anterolateral and posteromedial (after the location of their attachment to the LV), and which are attached to the mitral leaflets via the chordae tendineae.
Each supply all Chordae
3 Groups of Chordae Tendinae
they are categorized into three groups:
first order or marginal chordae, which attach to the free edges of the mitral leaflets
second order or strut chordae, which attach to the ventricular surface of the leaflets (away from the free edges)
third order or basal chordae, which run directly from the ventricular wall (rather than the papillary muscles) to the ventricular surface of the posterior leaflet, usually near the annulus.
Coaptation and Apposition
Coaptation: closing of Leaflets
Apposition: overlap of leaflet tips
First Order Chordae
first order or marginal chordae, which attach to the free edges of the mitral leaflets
Second Order Chordae
second order or strut chordae, which attach to the ventricular surface of the leaflets (away from the free edges)
Third Order Chordae
third order or basal chordae, which run directly from the ventricular wall (rather than the papillary muscles) to the ventricular surface of the posterior leaflet, usually near the annulus.
LA Anatomical location
Back of heart, anterior to oesophagus
Focus for thrombus formation
LAA
Eustachian Valve
embryological remnant, may be seen in the rA near the junction with the inferior vena cava
Tricuspid valve cusps
three cusps –in order of decreasing size, these are called the anterior, posterior and septal cusps.
PV Cusps
valve itself is structurally similar to the aortic valve, having three cusps (called anterior, left and right).
LA Contraction
LA is not just a passive conduit between the pulmonary veins and the LV, but contracts during atrial systole (immediately after the onset of the P wave) to provide additional diastolic filling of the LV (the ‘atrial kick’).
Ventricular filling phase
begins as the mitral valve opens and blood flows into the LV from the LA.
this phase ends when the mitral valve closes at the start of ventricular systole.
towards the end of the ventricular filling phase, atrial systole (contraction) occurs, coinciding with the P wave on the ECG, and this augments ventricular filling.
Layers of Pericardium
there is an outer fibrous layer –the fibrous pericardium –which blends with the diaphragm inferiorly, and an inner layer –the serous pericardium –which itself has two layers (the parietal pericardium, continuous with the fibrous outer layer, and the visceral pericardium, which is the epicardium of the heart).
Isovolumic Relaxation phase
commences with AV closure
Pressure within the LV falls during this phase (but volume remains constant), until the LV pressure falls below LA pressure.
At this point, the pressure difference between LA and LV causes the mitral valve to open and isovolumic relaxation ends.
Gaps in Pericardium
pericardium contains ‘gaps’ where vessels enter and leave the heart, and the pericardium forms a small sleeve around these vessels. As a result, there is a small pocket of pericardium around the aorta/pulmonary artery (transverse sinus) and between the four pulmonary veins (oblique sinus).
Moderator Band
stretches between the free wall and the septum in RV
4 Phases of Cardiac Cycle
- Isovolumic contraction
- Ventricular Ejection
- Isovolumic relaxation
- Ventricular filling
Phases of Cardiac Cycle in Systole and Diastole
Systole: phases 1 + 2
Diastole: Phases 3 + 4
Isovolumic Contraction phase
MV closes
Increase ventricular pressure at start of systole as walls contract
Constant volume until AV opens
Ventricular Ejection phase
AV Opens
Blood is ejected from LV to Aorta
LV Volume falls
Pressure rises until it peaks and then declines
Eventually pressure drops low enough and AV closes
Normal RA Pressure (mmHg)
Mean 0-5mmHg
Normal RV Pressure (SBP and DBP in mmHg)
Systolic 15-25mmHg
Diastolic 0-5mmHg
Pulmonary Artery Pressure
SBP and DBP
Systolic 15-25 mmHg
Diastolic 5-12 mmHg
LA Pressure (mmHg)
Mean 5-12 mmHg
LV Pressure
SBP 100-140 mmHg
DBP 5-12 mmHg
Normal Aortic Pressure
SBP: 100-140 mmHg
DBP: 60-90 mmHg
S1
Closure of Mitral and Tricuspid Valves
S2
Closure of aortic and pulmonary valve
Physiologically Split S2
During expiration S 2 occurs as a single sound, but during inspiration the return of venous blood to the right heart makes the pulmonary valve close slightly later than the aortic valve, causing normal physiological splitting of S 2 with the pulmonary component (P2 ) occurring just after the aortic component (A2 ).
Fixed Splitting S2
the presence of an ASD removes this respiratory variation in S 2 , so that the slight gap between A2 and P2 is there all the time (‘fixed splitting’).
