Heart and Mediastinum Flashcards
Which part of the mediastinum contains the thymus?
Anterior mediastinum
Until what vertebrae does the posterior mediastinum continue until?
12th thoracic vertebrae
What is held in the superior mediastinum?
Arch of aorta, great vessels, trachea, oesophagus, thoracic duct, phrenic and vagus nerves
How do the phrenic and vagus n pass through the mediastinum compared to the hilum of the lungs?
Phrenic - anterior
Vagus - posterior to subclavian vessels
What is held in the anterior mediastinum?
Internal thoracic vessels, fat, connective tissue, maybe some thymus
What arteries can be used for CABG?
Internal thoracic arteries
In child x-rays, what is the sign to recognise the thymus gland?
‘Sail’ sign - normal - shrinks in adults
What is held in the posterior mediastinum?
Oesophagus and plexus, descending aorta, thoracic duct, sympathetic chain and azygous system
What is held in the middle mediastinum?
Heart, pericardium, origins of the great vessels and phrenic nerves
What is the pericardium composed of?
Fibrous pericardium - tough outer connective tissue
Serous pericardium - visceral and parietal layers
What forms the pericardial cavity and what does it contain?
Between the parietal and visceral layers - lubricating pericardial serous fluid
What can be used in surgery to clamp arterial flow of the heart?
Transverse pericardial sinus (separates arteries from veins)
How do papillary muscles help valves?
Papillary muscles are extensions of ventricular wall, CONTRACT - prevent blood to black flow into atria during ventricular systole (Unidirectional flow)
What are the main functions of the fibrous cardiac skeleton?
Mechanical stability Electrical insulation (stop conduction from atria to ven) Anchor point for cardiac muscle and valve cusps AV node is only route for signal conduction
How many cusps do the aortic and pulmonary valves have?
3 cusps - semi-lunar
How do the cusps help the aortic and pulmonary valves?
Ventricular diastole - reverse flow blood catches in the pockets - closes valve
Ventricular systole - valve cusps pushed toward vessel walls and OPEN
What are the two main defects the disturb pumping efficiency of the heart?
Stenosis - valve does not open fully
Insufficiency - regurg or failure of valve to close - backflow
Which valves are most affected by heart disease and how?
Mitral and aortic
inc turbulence
What happens if the mitral valve prolapses?
one or both leaflets are enlarged, redundant or FLOPPY
Blood regurgitates into LA, when LV contracts -> Late systolic murmur
What happens if there is aortic stenosis?
often the result of degenerative calcification
Results in LV hypertrophy
What happens if the tricuspid or pulmonary valve is affected? What are the clinical presentations?
Often the result of infection, rheumatic fever or infective endocarditis (inflammation of heart lining)
Splinter hemorrhages
Where do coronary arteries arise from?
the coronary sinus above the cusps of aortic valve
Main inflow = dyastole
Which coronary artery is dominant in 60% of patients?
RCA -> gives rise to PIVA
LCA - 40% of patients gives rise to PIVA
What does the RCA usually supply?
Right atrium & ventricle
SA node
AV node
Posterior IV Septum (minority of septum)
What does the LCA supply?
Left Atrium & Ventricle
AV bundle
Right & Left bundle branches
Anterior IV septum (majority of septum)
What is the LAD artery supply? What is another name for it?
Anterior interventricular artery
(aka Left Anterior Descending (LAD))
R & L ventricles
Anterior 2/3rds of septum
Where does blood from the coronary veins drain into?
Right atrium via coronary sinus
What are the surface anatomy points for the 4 edges of the heart?
2nd L CC - 1cm lateral to sternum
5th L ICS - Just medial to MCL
3rd R CC - 1cm lateral to sternum
6th R CC - 1cm lateral to sternum
What sympathetic chain nerves cause increase in heart rate and contractility?
T1-4 nerves
What are the branches of the RCA?
- Sinoatrial node artery (supplies SAN node and both atria)
- Anterior ventricular arteries
- Marginal artery (reaches apex)
- PIVA in RCA dominant people (supplies posterior 1/3 of septum, supplies AV node)
What are the branches of the LCA?
- Sinoatrial node artery (supplies both atria)
- Circumflex artery (supplies left atrium & ventricle, continues as PIVA in 40%)
- Anterior interventricular artery aka LAD (supplies R+L ventricles, anterior 2/3 of septum)
- Marginal artery (left ventricle to apex)
- PIVA in LCA dominant (supplies posterior 1/3 of septum, supplies AV node)
