Heart

How many leaflets/cusps does each valve have?

Mitral: 2

Tricuspid: 3

Pulmonary: 3

Aortic: 3

Which pairs of valves are on the same side of the heart?

Tricuspid/pulmonary

Mitral/aortic

What forms the right border of the heart?

Right atrium

What forms the left border of the heart?

Left ventricle

What forms the inferior border of the heart?

Right ventricle

Describe the walls of the right atrium.

Anterior (inc. atrial appendage/auricle) is trabeculated - pectinate muscle

Posterior is smooth and forms sinus venarum

Separated by crescent-shaped crista terminalis

Where does the right auricle extend?

Around the origin of the aorta

What is found in the walls of the ventricles, excluding outflow tracts?

Trabeculations - muscular ridges known as trabeculae carnae

What connects to the leaflets of the tricuspid valves?

Three sets of papillary muscles via chordae tendinae

What is the purpose of the papillary muscles?

Contract in ventricular systole to prevent valve cusps prolasping into atrium

The right ventricular outflow tract is...

Smooth

At what level is the pulmonary valve?

3rd costal cartilage

What is the pulmonary valve also known as?

Semilunar

What is found on the posterior surface of the heart?

Left atrium

What does the left atrium drain?

Four pulmonary veins

What does the right atrium drain?

Superior and inferior vena cava

Describe the walls of the left atrium.

Mainly smooth-walled. Left atrial appendage/auricle is trabeculated (pectinate muscles).

What forms the apex of the heart?

Left ventricle

At what level is the aortic valve?

3rd intercostal space

The left ventricular outflow tract is...

Non-muscular

What are the two heart sounds called and what do they correspond to?

S1 - high-pitched 'lub'

Closure of mitral/tricuspid valves at the end of diastole.

S2 - lower-pitched 'dub'

Closure of aortic/pulmonary valves at the end of systole.

Where is the apex of the heart?

Mid-clavicular line, 5th intercostal space

Where do the coronary arteries arise?

Right and left aortic sinuses, just above and behind aortic valve cusps

Where does the right coronary artery pass in?

Coronary sulcus - border between atria and ventricles

Where does the left coronary artery pass in?

Atrioventricular groove

Branches of the right coronary artery?

> AV nodal artery

> Right marginal artery

> 60% - SA nodal artery

> 70% - posterior interventricular artery

Branches of the left coronary artery?

> Left anterior descending artery

> Circumflex artery

> Left marginal artery

> 30% - posterior interventricular artery

LMA and PIA are branch of circumflex

Where does the left anterior descending artery pass in?

Anterior interventricular groove

Where does the circumflex artery pass in?

Atrioventricular groove, to posterior heart

Blood supply of the interventricular septum?

Anterior 2/3 - left anterior descending artery (left)

Posterior 1/3 - posterior interventricular artery (70% right)

Describe venous drainage of the heart

Drains to the coronary sinus on the posterior of the heart, from the great, middle and small cardiac veins.

Coronary sinus drains directly into right atrium.

What determines coronary dominance?

Which artery gives rise to the posterior descending/interventricular artery.

What coronary dominance is most common?

Right - 70%

Left - 10%

20% codominance - supplied by both the right coronary artery and the circumflex branch of the left coronary artery

Broadly, where does autonomic innervation of the heart come from?

Cardiac plexus

What nerves give parasympathetic supply to the heart?

Vagus and recurrent laryngeal

What nerves give sympathetic supply to the heart?

Nerves from the cervical & upper thoracic sympathetic ganglia - T1-T5

Where is the SAN located?

Crista terminalis of right atrium

Arterial supply of the SAN?

Atrial branch of right coronary artery

Where is the AVN located?

Base of the atrioventricular septum, left of IVC opening

How are impulses forced through the AVN?

Insulating, fibrous annulus fibrosis separates atria and ventricles otherwise

Where do impulses travel past the AVN?

> Bundle of His

> Left & right bundle branches

> Purkinje fibres across ventricular myocardium

Where is cardiac ischaemic pain referred and why?

Viscerosensory fibres pass along sympathetic nerves & terminate in upper thoracic spinal cord.

Ischaemic pain is therefore referred to T1-T5 dermatomes.

Severe, crushing central chest pain classically radiating to inner left arm, sometimes left neck & naw.

What shunts exist in fetal hearts and what do they connect? What kind of blood do they carry?

Foramen ovale - right to left atrium, highly oxygenated blood (from UVs)

Ductus venosus - umbilical vein to innferior vena cava, highly oxygenated blood

Ductus arteriosus - pulmonary trunk to aortic arch, moderately oxygenated blood

What is the purpose of the ductus arteriosus?

Allows blood to bypass the lungs, protecting the developing lungs from circulatory overload

What happens to the foramen ovale at birth?

Shuts to form the fossa ovalis

Describe the development of the atrial septum.

Thin *septum primum* grows down towards endocardial cushion. Before it fully fuses, foramen known as *foramen primum*.

Programmed apoptosis causes series of perforations at top of this septum - *foramen secundum*

Thick, muscular *septum secundum* grows down to right of septum primum - does not fuse with AV septum, leaving *foramen ovale*

Unidirectional as holes are not aligned, and septum primum can pushed by blood but septum secundum cannot

What happens to the ductus arteriosus at birth?

Constricts when blood PO2 > 50mmHg, as fetus takes first breaths.

Forms ligamentum arteriosum.

What happens to the ductus venosus at birth?

Forms the ligamentum venosum

What happens to the umbilical vein at birth?

Constricts to prevent blood loss via the umbilicus.

Forms the ligamentum teres, the free edge of the falciform ligament of the liver.

What might cause an atrial septal defect?

Patent foramen ovale - failure of adhesion of flap valve of septum primum with septum secundum at birth

Failure of fusion of the septum primum with endocardial cushions

What are the consequences of an atrial septal defect?

Blood shunts back from the left to right atria.

Can cause:

> right-sided overload

> pulmonary hypertension

> atrial arrhythmia

Where in the ventricular septum are defects most commonly found?

Membranous portion of septum

What are the consequences of a ventricular septal defect?

Shunting of blood from left to right ventricle.

Causes:

> increased pulmonary blood flow

> pulmonary hypertension

> reduced cardiac output

What is Tetralogy of Fallot?

Cyanotic heart condition characterised by:

> large ventricular septal defect

> overriding aorta

> right ventricular outflow obstruction

> right ventricular hypertrophy

Requires surgical repair in first year of life.

What artery supplies the left ventricle?

Left anterior descending, left marginal, circumflex, posterior interventricular

What artery supplies the right atrium?

Right coronary artery, maybe a little of the left anterior descending

What artery supplies the right ventricle?

Right coronary, right marginal, posterior interventricular

What artery suplies the left atrium?

Left circumflex

What artery supplies the apex of the heart?

Right marginal

When in the cardiac cycle are coronary arteries perfused?

Diastole

Arterial supply of the AVN?

Atrioventricular nodal artery, branch of the right coronary artery

What is the cardiothoracic ratio in health?

Why might a patient have two apex beats?

Aneurysm of the left ventricle

How can you feel right ventricular dilatation on the surface?

Right ventriclar 'heave' - anterior surface pushed forwards

Names of the aortic leaflets?

According to relationship with coronary arteries

> right coronary cusp

> left coronary cusp

> non-coronary cusp

What is the name of the ball-and-cage valve?

Starr Edwards