CVS Flashcards
Cardiovascular risk assessment
QRISK
risk of having a cardiac event in the next 10 years
Used for those up to 84 years old
Shouldn’t be used in those with CVD already or those over 85 or high risk of developing CVD
repeat every 5 years
which details are needed for QRISK assessment?
age sex ethnicity postcode clinical info - smoking status, medical and family history, systolic BP, height, weight and total cholesterol/ HDL-cholesterol ratio
what are cardiac enzymes?
released into the circulation when myocardial necrosis occurs - e.g. MI
what are the cardiac enzymes?
myoglobin
troponin
creatine kinase
myoglobin
non-specific because come from skeletal muscles
troponin
important in the contractile apparatus of cardiac myocytes
released between 3-4 hours after MI
other non-related causes of raised troponin
remains in blood for 10 days
creatine kinase
muscle enzyme that exists as isoenzymes
specific to myocardial cells
better for detection of re-infarction as remains in blood for 3-4 days but released 3-4 hours after event
regulation of BP
short term and long term
long-term regulation of BP
renin-angiotensin-aldosterone
ADH
Natriuretic peptides
prostaglandins
renin
peptide hormone released by granular cells in juxtaglomerular apparatus in kidney
what is renin released in response?
sympathetic stimulation
reduced sodium-chloride delivery to DCT
decreased blood flow to kidney
what does renin do?
converts angiotensinogen to angiotensin I which is converted to angiotensin II using angiotensin-converting enzyme -ACE.
what does angiotensin II do?
a potent vasoconstrictor that acts directly on the kidney to increase sodium reabsorption in PCT. Sodium is reabsorbed via a sodium-hydrogen exchanger
promotes the release of aldosterone
what does ACE do?
converts angiotensin I to II
breaks down bradykinin which is a potent vasodilator - potentiates constricting effects
what does aldosterone do?
promotes salt and water retention by acting at DCT to increase expression of epithelial sodium channels
increases activity of basolateral sodium-potassium ATP-ase, increasing the electrochemical gradient for movement of sodium ions
more sodium collects in kidney tissue and water follows by osmosis cause decreased water excretion and increase blood volume and BP
where is ADH released?
organum vasculosum of lamina terminalis
why is ADH released?
in response to thirst or increased plasma osmolarity
what does ADH do?
increases permeability of collecting duct to water by inserting aquaporin channels into apical membrane
stimulates sodium reabsorption from thick ascending limb of loop of Henley which increases water reabsorption which increases plasma volume and decreases osmolarity
what is another control of BP?
natriuretic peptides
Natriuretic peptides
atrial natriuretic peptide
Atrial natriuretic peptide
synthesised and stored in cardiac myocytes
released when atria are stretched which indicates a high BP
secretion is low when BP is low
what does Atrial natriuretic peptide do?
promotes sodium excretion
dilates afferent arteriole of glomerulus increasing blood flow
inhibits sodium reabsorption along nephron
Prostaglandins
act as local vasodilators to increase glomerular flow rate and reduce sodium reabsorption
act to prevent excessive vasoconstriction triggered by sympathetic nervous and renin-angiotensin-aldosterone systems
what is the pericardium?
fibroserous membrane covering the heart and parts of great vessels
composition of pericardium
closed sac
2 layers
what are the layers of the pericardium?
fibrous pericardium
serous pericardium
what are the layers of the serous pericardium?
parietal
visceral
pericardial sinuses
transverse pericardial sinus
oblique pericardial sinus
heart wall layers
endocardium
myocardium
epicardium - visceral pericardium
what are the surfaces of the heart?
anterior
diaphragmatic
right pulmonary
left pulmonary
what are the borders of the heart?
right
inferior
left
superior
what does the right atrium do?
receives deoxygenated blood from superior and inferior vena cava and coronary veins
pumps blood through right atrioventricular orifice - tricuspid valve
what is the right auricle?
right atrial appendage
what is the coronary sinus?
receives blood from coronary veins, opens between the inferior vena cava and right atrioventricular orifice.
What is the interatrial septum?
solid muscular wall separates the 2 atria.
what does the left atrium do?
receives oxygenated blood from 4 pulmonary veins and pumps through left atrioventricular orifice - mitral valve
anatomy of left atrium
left auricle extends from superior aspect of chamber
inferior surface is divided into 2
what are the divisions of the inferior surface of the left atrium?
inflow portion
outflow portion
inflow portion of left atrium
receives blood from pulmonary veins
internal surface is smooth
outflow portion of left atrium
includes left auricle
lined with pectinate muscles
what does the right ventricle do?
pumps blood through pulmonary orifice - pulmonary valve into pulmonary artery
structure of right ventricle
triangular
can be divided into inflow and outflow portions which are separated by a muscular ridge - supraventricular crest
inflow portion of right ventricle
interior part covered by irregular muscular elevations - trabeculae carnae
what are the different types of trabeculae carnae
ridges
bridges
pillars
ridges
attached along their entire length on one side to form ridges
bridges
attached to ventricle at both ends, but free in the middle. Moderator band spans between inter ventricular septum and anterior wall of right ventricle. Have an important conductive function
Pillars
anchored by their base to ventricles. Apices are attached to fibrous cords which are attached to the 3 tricuspid valve cusps. By contracting the papillary muscles pull on the fibrous cords to prevent prolapse of the valve leaflets during ventricular systole.
outflow portion of right ventricle
leads to pulmonary artery located in superior aspect of ventricle derived from embryonic bulbs cordis visible different from rest of right ventricle smooth walls no trabeculae carnae
Interventricular septum
separates the 2 ventricles
made up of superior membranous and inferior muscular parts
muscular part forms most of septum - same thickness of left ventricular wall
membranous part is thine er and part of the fibrous skeleton of heart
what does the left ventricle do?
pumps blood through aortic orifice - aortic valve into aorta
forms apex of heart
structure of left ventricle
divided into inflow and outflow portion
inflow portion of left ventricle
walls lined by trabecular carneae and there are 2 papillary muscles which attach to cusps of mitral valve
outflow portion of left ventricle
aka aortic vestibule
It is smooth-walled with no trabeculae carneae and comes from bulbs cordis
what is the role of the great vessels?
carry blood to and from heart
mainly located in middle mediastinum
what are the great vessels of the heart?
aorta
pulmonary arteries
pulmonary ary veins
superior and inferior vena cava
Aorta
largest artery
carries oxygenated blood to rest of body
arises from aortic orifice at base of LV
inflow via aortic valve
branching of the aorta
first segment = ascending aorta within pericardium
coronary arteries branch from aorta
second segment = arch of aorta
major arteries to head, neck and upper limbs come from aortic arch - brachiocephalic trunk, left common carotid and left subclavian
third segment = descending aorta, continues down through diaphragm into abdomen
pulmonary arteries
receive deoxygenated blood from RV and deliver to lungs for gas exchange
begin at pulmonary trunk
at T5-6 pulmonary trunk splits into R and L pulmonary arteries
what is the pulmonary trunk?
thick
short vessel
separated from RV by pulmonary valve
left pulmonary artery
supplies blood to left lung
bifurcates into 2 branches to supply each lobe of the lung
right pulmonary artery
thicker
longer
supplies blood to right lung, divides into 2 branches
pulmonary veins
receives oxygenated blood from lungs and delivers to left side of heart
how many pulmonary veins are there?
4, superior and inferior for each lung
pulmonary vein distribution
superior Pulmonary veins return blood from upper lobes of lung
inferior pulmonary veins return blood from lower lobes of lung
left inferior pulmonary vein in hilum of lung
right inferior pulmonary vein runs posteriorly to vena cava
superior vena cava
receives deoxygenated blood from upper body - superior to diaphragm - excluding the lungs and heart
delivers to right atrium
formed by merging of brachiocephalic veins
located in right side of superior mediastinum, then middle mediastinum next to ascending aorta.
inferior vena cava
receives deoxygenated blood from lower body - inferior to diaphragm delivering it to the heart
formed in pelvis by common iliac veins combining
travels through the abdomen, collects blood from hepatic, lumbar, gonadal, renal and phrenic veins
passes through diaphragm and enters pericardium at T8 level
drains into inferior portion of right atrium
what are the layers of the heart wall?
endocardium subendocardial layer myocardium subepicardial layer epicardium
endocardium
innermost layer lines cavities and valves of heart comprised of loose connective tissue and simple squamous epithelial tissue regulates contractions aids cardiac embryological development
subendocardial layer
between endocardium and myocardium, joining them together
consists of layer of loose fibrous tissue which contains vessels and nerves of conducting system of heart
contains purkinje fibres
what can damage to the subendocardial layer cause?
arrhythmias
myocardium
composed of cardiac muscle
involuntary striated muscle
responsible for contractions
what happens in an MI?
blockage of coronary arteries so myocardium loses its oxygen supply and undergoes ischaemic change
subepicardial layer
between myocardium and epicardium, joining them together
epicardium
outermost layer
formed by visceral layer of pericardium
composed of connective tissue and fat
connective tissue secretes a small amount of lubricating fluid into pericardial cavity
outer surface lined by simple squamous epithelial cells
what is the role of heart valves?
ensure blood flows in only 1 direction
composed of connective tissue and endocardium
there are 4
what are the 4 heart valves?
atrioventricular valves - tricuspid, mitral
semilunar valves - pulmonary and aortic
tricuspid valve
between right atrium and right ventricle
3 cusps
mitral valve
between left atrium and left ventricle
2 cusps
pulmonary valve
between right ventricle and pulmonary trunk
3 cusps
aortic valve
between left ventricle and ascending aorta
3 cusps
atrioventricular valves
close during start of ventricular systole
produces first heart sound
what are the cusps of the tricuspid valve?
anterior
septal
posterior
base of each cusp anchored to a fibrous ring that surrounds the orifice
what are the cusps of the mitral valve?
anterior and posterior
base of each cusp is secured to a fibrous ring surrounding the orifice
structure of atrioventricular valves
supported by attachment of fibrous cords - chordae tendineae to the free edges of the valve cusps
chord tendineae are attached to papillary muscles on anterior surface of ventricles
papillary muscles contract during ventricular systole to prevent prolapse of the valve leaflets into atria
papillary muscles
5 in total
3 in RV to support tricuspid
2 in LV to support mitral
semilunar valves
close at beginning of ventricular diastole
produces second heart sound
what are the cusps of the pulmonary valve?
left
right
anterior
What are the cusps of the aortic valve?
left
right
posterior
how do the semilunar valves work?
as blood recoils during ventricular diastole it fills the aortic sinuses and enters the coronary arteries to supply the myocardium
sides of each leaflet are attached to walls of outflow vessel
at beginning of ventricular diastole blood flows back towards the heart and fills sinuses, pushing the valve cusps together causing it to close
coronary arteries
2 main ones which branch to supply the heart
left and right main coronary artery
where do the main coronary arteries arise from?
left and right aortic sinuses within aorta
what are aortic sinuses?
small openings within aorta behind left and right flaps of aortic valve
when heart is relaxed the back flow of blood fills these valve pockets allowing blood to enter the coronaries
left coronary artery
branches into left anterior descending/ anterior inter ventricular artery
gives off left marginal artery
gives off left circumflex artery
right coronary artery
branches to form right marginal artery and sometimes posterior inter ventricular artery
cardiac veins
blood from subendocardium drains into larger veins and empties into coronary sinus
what is the coronary sinus?
main heart vein on posterior surface in coronary sulcus
drains into right atrium
what is the coronary sulcus?
runs between left atrium and left ventricle
coronary artery disease
reduction in blood flow to myocardium
result of narrowing/ blockage of coronaries through reduced blood flow by physical obstruction or changes in vessel wall
what causes coronary artery disease?
atherosclerosis thrombosis high BP diabetes smoking
Angina
caused by narrowing of coronary arteries
pain on exercise due to lack of oxygen to heart
resolved on rest
what happens in an MI?
sudden occlusion of an artery results in infarction and necrosis of myocardium
causes section of heart to be unable to beat
ECG leads can be used to locate the artery that has caused the MI
what is the SAN?
collection of specialised pacemaker cells in upper wall of right atrium where the superior vena cava enters
what is the AVN?
within atrioventricular septum
near opening of coronary sinus
What is the bundle of His?
continuation of specialised tissue of AVN and transmits the electrical impulse from AVN to prukinje fibres of ventricles
how does the heart contract?
- pacemaker cells spontaneously generate electrical impulses
- wave of excitation spreads via gap junctions across both atria
- causing atrial contraction - atrial systole
- blood moves from atria to ventricles
- after the impulses have spread across atria they converge at AVN
- AVN delays the impulses by 120ms to ensure atria have enough time to fully empty blood into ventricles before ventricular systole
- wave of excitation passes from AVN into atrioventricular bundle
- wave of excitation descends the membranous part of interventricular septum
- then divides into 2 main bundles:
what are the 2 bundles the electrical impulses pass through?
- right bundle branch = conducts impulse to purkinje fibres of right ventricle
- left bundle branch = conducts impulse to purkinje fibres of left ventricle
purkinje fibres
subendocardial plexus of conduction cells
abundant with glycogen
extensive gap junctions
located in subendocardial surface of ventricular walls
what do purkinje fibres do?
able to rapidly transmit cardiac action potentials from atrioventricular bundles to myocardium of ventricles
allows coordinated ventricular contraction - systole
blood is moved from right and left ventricles to pulmonary artery and aorta
how is heart rate regulated?
rate at which SAN generates impulses is influenced by ANS
what does the sympathetic NS do?
increases firing rate of SAN and increases HR
accelerant nerve, postganglionic fibres from sympathetic trunk innervate SAN and AVN
they release noradrenaline which acts on Beta 1 adrenoreceptors to increase pace
what does the parasympathetic NS do?
decreases firing rate of SAN and decreases HR.
Vagus nerve synapses with postganglionic cells in SAN and AVN which causes acetylcholine to bind to M2 receptors
balance of autonomic nervous system
at rest parasympathetic input dominates
initial increases in HR occur due to reduced parasympathetic outflow
heart rate over 100bpm is via increase in sympathetic outflow
hormonal control of HR
adrenaline released from adrenal medulla increases HR
how can menopause affect CV health?
decline in oestrogen
oestrogen keeps artery wall flexible so they can relax and expand to accommodate blood flow
BP starts to increase
decline in oestrogen increases cholesterol
oestrogen reduces the build-up of fatty plaque
LDL cholesterole tends to increase while HDL declines/ stays the same
triglycerides in blood increase
all these are risk factors for CVD
