CVS Flashcards
Where is apex of the heart found?
5th intercostal space on the left
What is the transverse pericardial sinus?
Behind the artery and pulmonary trunk, you can insert a scalpel or finger. This is often used in surgery to clamp the aorta shut
What are the names of the valances on the right of the heart?
Tricuspid and pulmonary
What are the names of the valves on the left of the heart?
Mitral and aortic
Why do valves open and close?
Pressure differences on either side of the valve
What prevents inversion of valves during systole?
During systole there is high pressure which would cause inversion of the mitral and tricuspid valves if they were not attached to papillary muscles via chordate tendonae
What are the three layers of the pericardium?
Outer fibrous layer
Parietal serous membrane
Visceral serous membrane
What is cardiac tamponade and how is it treated?
Cardiac tamponade= the pericardial sac filling with fluid meaning that the heart is compressed as the fibrous layer means that the heart cannot expand.
This is treated by pericardiocentesis which is inserting a needle to remove this fluid
What do regurgitations mean?
That valves are incompetent and don’t close properly so blood moves back giving turbulent blood flow, which is heard as a murmur.
What is mitral regurgitation
A murmur which occurs in systole after the mitral valve closes and when the atria contracts blood moves back to the atria causing turbulent flow
What is aortic regurgitation?
This occurs during diastole, when the valve shuts the blood from the aorta fall back into the ventricle causing turbulent flow
What is mitral stenosis?
It is heard in diastole when the valance is meant to be opened but does not open fully the blood flows through at a higher pressure
What is aortic stenosis?
It is heard in systole as the valves are meant to open then but as it doesn’t fully open blood flows through at high pressure
What is S3?
A third heart sound, which is heard in early diastole, which is normal in children and athletes but a sign of heart failure in adults, this is not valvular origin
When do you hear right sided heart sounds?
Inspiration
Because there is lower pressure in thoracic cavityso more blood goes to lungs, so increased blood flow in RHS of the heart.
What are best heard during expiration?
Right sided heart murmurs as the diaphragm contracts forcing blood out the lungs which then travels to the left hand side
Why would you ask a patient to hold their breathe when listening to chest sounds?
So you can definitely hear heart sounds but not lung sounds- a wheeze may sound like a heart sound
Where do you listen for heart sounds?
All- aortic valve(2nd-3rd intercostal space on RHS)
Prostitutes- pulmonary valve (2nd-3rd LHS intercostal space)
Take- tricuspid valve ( left sternal border)
Money- mitral valve- apex of heart
What are the pressures of the different areas in the heart?
RA= 0-4 RV= 25/4 PA= 25/10 LA= 5 LV= 120/4 A= 120/80
What is perfusion rate?
The rate of blood flow
What is cardiac output for the average 70 kg male?
5l per minute
But can increase to 25l per minute
What are capacitance vessels?
They can increase the volume of blood that they hold without increasing pressure
What are resistance vessels?
Arterioles can contract to the restrict blood flow
Stroke volume equation
Stroke volume= volume of blood pumped at each beat (70ml) at heart rate of 70bpm, this gives 5 litres of blood per minute
Cardiac output equation
Cardiac output= stroke volume x heart rate
What is afterload?
The pressure of the wall of the left ventricle during ejection
What is preload?
The amount of the ventricles are stretched in diastole
Why do MIs occur?
Cardiac arteries are end arteries, so when they are blocked there will be a lack of oxygen to the left ventricle. Diffusion distance is too great so cannot supply.
What is a coronary sinus?
The venous drainage of the heart to the RA, through the coronary osteomyelitis
What give the greatest resistance?
Arterioles amd precapillary sphincters can restrict flow. Total peripheral resistance increases arteriole pressure but decreases venous pressure
What is the Frank starling law of the heart?
The more that the heart fills the harder it will contract the bigger the stroke volume. An increase in venous pressure will fill the heart morebut how much the ventricles fill depends on their compliance. A normal heart will fill to a volume of 120 ml and a pressure 10mmHg.
What are causes of aortic stenosis?
Degenerative ( fibrosis, calcification)
Congenital (bicuspid form)
Chronic rheumatic fever
Old age
What does aortic stenosis sound like?
Crescendo decrescendo murmur
Causes of mitral valve stenosis
Rheumatic fever
Fusion of valvular leaflets
Causes of aortic regurgitation
Aortic root dilation
Valvular damage
Mitral valve regurgitation causes
Myxomatous degeneration
Damage of papillary muscles after after a heart attack
Rheumatic fever causes leaflet fibrosis
Left ventricular dilation separating leaflets
What is turbulent blood flow?
Blood flow chaotic in all directions, this occurs when the rate of flow becomes too great, if blood passes by an obstruction when blood makes a sharp turn or when there’s increased resistance to flow.
You can feel thrill- vibrations or a noise a bruit.
What is laminar blood flow?
Where blood flow is in streamlined
Blood normally has laminar blood flow
What does an increase in viscosity mean?
Fluid is harder to pump out of the heart, so there is a decreased velocity and an increased resistance to flow meaning that oxygen delivery is reduced
The most common cause of increased velocity is multiple myeloma, thrombocytaemia or leukaemia
What is pulse pressure?
The peak systolic pressure- end diastolic pressure
Average is approx. 40 mmHg
What is mean arterial pressure?
Diastolic pressure+ 1/3 of pulse pressure
Average 93 mmHg
What is a pulse
A change in pressure
It is a shock wave- a steep change in pressure
Why causes minor changes in blood viscosity?
Raised levels of acute plasma proteins, complement factors, CRPs
What causes a thread pulse
LV failure
Dehydration
Bleeding
Aortic valve stenosis
What causes a bounding pulse?
Low peripheral resistance- exercise, pregnancy and hot baths
What is the measurement of pressure?
Pounds per square inch
What is Wiggers diagram?
Plotted for the left of the heart
The right would be the same but smaller
How does the heart conduct action potentials?
Specialised conduction cells in the sino atrial node which generates action potentials. Activity spreads overatrial wall atria conducts electricity. AV node spreads excitation down the septum towards the ventricles, delays contraction to allow excitation. The excitation spreads towards the ventricles down the perkinje fibres. Ventricles contract from the apex upwards . The intercalated discs allow the conduction sod signals.
What changes when the heart rate changes?
Length of diastole
What is systole?
Contraction and ejection do blood from the ventricles
What is diastole?
Relaxation and filling of the ventricles
What are the phases of the cardiac cycle?
Atrial contraction Isovolumetric contraction Rapid ejection Reduced ejection Isovolumetric relaxation Rapid filling Reduced filling
What occurs in atrial contraction?
Atrial pressure rises due to atrial systole- A wave.
P wave seen on the ECG due to atrial depolarisation
Atrial contraction last 10% of ventricular filling.
What happens in isovolumetric contraction?
Mitral valve closes as ventricular pressure exceeds that of the atria.
This is a rapid increase in ventricular pressure as they contract.
All valves are closed
Slight rise in atrial pressure to give the C wave.
No change in ventricular volume.
QRS complex on ECG.
Lub (first heart sound) due to closing of mitral valve
What occurs during rapid ejection?
Aortic valve opens as the pressure of the ventricle exceeds that of the aorta. Atrial pressure declines as the contraction of the ventricles, which pulls the base of the atria walls down.
What occurs during reduced ejection?
Atrial pressure gradually rises due to venous return from the lungs, ventricular repolarisation creates the T wave on the ECG.
Repolarisation of the ventricles leads to a decline in tension and rate of ejection falls.
What occurs during isovolumetric relaxation?
Ventricular pressure falls below the aortic pressures the aortic valve shuts creating dub the second heart sound. Brief back flow causes the closure of the valve.
The dicrotic notch is seen in aortic pressure when valves close due to slight decline in pressure.
Rapid decline in ventricular pressure, all volumes remain constant as all valves are closed
What is rapid filling?
Fall in atrial filling, mitral valve opens
Ventricles fill rapidly
Normally silent but in some children can hear it as S3 an extra heart sound
What occurs during reduced filling?
Rate of filling decreases- known as diastasis, fills 90% of ventricle before atrial contraction
What are congenital heart defects?
Heart problems people are born with normally due top a problem with embryology
Most common types of Herat defects but 90% live to adulthood, so survival rate has increased
Pregnancy with congenital heart defects can lead to maternal death
Can be genetic
Can arise due to differing needs of the fetus or a newborn
What are acyanotic defects?
Shunts from left to right
What is PDA?
Patent ductus arteriosus
Acynatic defect
It is when the ductus arteiosus does not fully close so blood flows from the aorta into the pulmonary artery
What is atrial septal defect?
It occurs when wither the septum primula or septum secondum is too small or resorped so blood can continue to pass from the left atrium to the right atrium, increasing pulmonary flow which causes the right ventricle to over load, pulmonary hypertension and right heart failure
What is ventricular septal defect?
Most common type of congenital heart defect
When there is a gap in memebraenous portion of IV septum, causes the left ventricular overload as blood passes from RV to LV.
Often seen in Down’s syndrome
What is coarctation of the aorta?
Narrowing of the aorta
What are cyanosis defects?
Lack of oxygen causes blue discolourisation of the skin
What is hypoplastic left heart syndrome?
Underdevelopment of the left side of the heart as there is a defect in the mitral and aortic valves. As the left ventricle is not used to being used there is no flow so it is underdeveloped.
What is transposition of the great arteries?
When the aorta arises from the right ventricle and the pulmonary trunk arises arises from the left ventricle
Oxygenated blood is pumped back to the lungs
Deoxygenated blood is pumped around the body.
Not fatal in foetal life due to bidirectional shunting
What is tetralogy of Fallot?
Defect in the ventricular septum. This causes an overriding aorta decrease in the size of the pulmonary trunk- pulmonary stenosis, but right ventricular hypertrophy as the pressure to try to push blood through the smaller pulmonary trunk
What is tricuspid atresia
When there is no passage from the right atrium to the right ventricle so RV is under developed due t the lack of use
What is pulmonary atresia?
It is when blood flows from RA to LA
What sets the resting membrane potential?
Potassium permeability
What is the conc of potassium ions in and outside of the membrane?
140 mM in
4mM out
What is the equilibrium potential in the heart?
-95mV
What is the electrical activity of the SAN?
Never has a resting potential
It has spontaneous action potentials.
The funny current/ the initial slope is slowly increasing to the threshold due to the opening of the HCN, which allow the influx of sodium ions.
During depolarisation there is a build up of soiudm channel deactivation
What is hyperkalamia?
High K+ cancer in blood
It makes the membrane potential, more positive, so it is more depolarised, this inactivated sodium channels , so there is a slower upstroke
Can cause asystole and causes increase in excitability
What are normal potassium levels in the blood?
3.5-5.5 mM
What is hypokalaemia?
Low concentration of potassium ions in the skin
May cause ventricular fibrilllation as the longer action potential leads to early depolarisations which can lead to oscillatations in the membrane potential
What is hyperkalaemia treated with?
Calcium gluconeogenesis which makes the heart less excitable and insulting with glucose which promotes potassium into cells
What happens t heart if actions potentials fire too slowly?
Bradycardia
What happens to the heart if action potentials fire too fast?
Tachycardia
What happens to the heart if action p[otentials fail?
Systole
The heart stops beating
What happens if the electrical activity in the heart becomes random?
Fibrillation
What does the autonomic nervous system do?
Regulates physiological features to maintain homeostasis - blood pressure, heart rate and temperature
It coordinates the bodies response to exercise
Involuntary control
How does the autonomic nervous system affect the heart?
It can decrease the heart rate it also affects peripheral resistance
What are baroreceptors?
Found in the carotid sinus and the arch of the aorta which an stretch in high pressure to increase the firing. This will signal the medulla oblongata which will signal the bogus nerve or the sympathetic trunk
What is the parasympathetic input to the heart?
Originates from the medulla
It acts in M2 receptors to decrease the heart rate at SAN cells
Parasympathetic activity decreases the speed of the pacemaker potential;
What is sympathetic input to the heart?
Originates from thoracic and lumbar spinal cord.
Caused by increase in stress
Acts mainly on beta 1 to cause an increase in heart rate
What is the baroreceptor reflex?
Adjusts sympathetic and parasympathetic reflex to alter cardiac output
They are found in the carotid sinus and the arch of the aorta
