CVS correction fc Flashcards
in atrial fibrolation, blood pools in the left atria. what feature of the left atria results in pooling of blood?
left auricle
how would you best describe the folding thatbrings the primitive heart tube into the thoracic region of the embryo?
Cephalo-caudal folding
which membrane channels of cardiac monocytes are inactivated in hyperkalaemia?
voltage-gated Na+ channels
which receptors allow for the release of calcium from inside the sarcoplasmic reticulum?
Ryanodine Receptors
where on the chest wall would you palpate for the apex beat?
Left fifth intercostal space, midclavicular line
why does a sudden build up of blood or fluid in the pericardial sac prevent the heart properly filling in diastole?
the outer layer of fibrous pericardium cannot expand causing the fluid to compress the heart
what structures does the transverse pericardial sinus separate?
The aorta and pulmonary trunk from the venous inflow to the heart
Where does the coronary artery which gives rise to the anterior interventricular and circumflex arteries arise from?
left aortic sinus
what causes the valves between the atria and ventricles to close?
small backflow of blood as the ventricles contract
Ventricles contract, increasing pressure of blood. This pushes the AV-valves closed. Papillary muscles contract at start of ventricular systole, tensioning the tendinous cords and preventing valve cusps from prolapsing into atria.
which congenital heart defect has a continuous murmur?
patent ductus arteriosus
In which week of development does the embryo fold?
4th
what is meant by the term pre-load?
The amount the ventricles are stretched in diastole
what channel type is responsible for the upstroke of the action potential in pacemaker cells?
L-type calcium channels
what is the typical resting membrane potential in ventricular myocytes?
-85mV
how is electrical activity in the heart initiated?
spontaneous depolarisation
The heart spontaneously activates; cells in the conductance system depolarise and fire action potentials, with the cells of the SA node depolarising quickest and setting the heart rate.
what causes discolouration of skin in varicose veins?
Macrophages oxidise iron from red blood cells that have leaked from the blood vessels. This oxidation causes the iron to rust under the skin which stains it
what is the cardiothoracic ratio?
ratio between the maximum cardiac diameter (horizontal width of the heart at the widest point) and the maximum thoracic diameter (horizontal width of the chest at the widest point) on a chest X-ray
(≤50% in healthy patient)
what type of drug is Amiodarone?
potassium channel blocker
what type of drugs are Verapamil and Diltiazem?
calcium channel blockers
what drug is an example of an ACE inhibitor?
Ramipril
all ACE inhibitors end in -pril
what drug reduces blood pressure by reducing circulating volume + reducing peripheral vasoconstriction?
angiotensin II receptor blocker - blocks the effects of AngII at peripheral vessels and will reduce aldosterone production thus reducing Na+ and water retention at kidney
how to calculate rate from an ECG?
300/time between R-R intervals
Why does pericarditis present with shoulder pain?
- Somatic afferent nerves
- Pericardium innervated by phrenic nerve which enters spine at level C3-C5
- Feel pain in dermatome associated with these areas
what drug can be given to relieve pain of stable angina?
GTN spray - vasodilator - relieves pain
what are some precipitants of angina?
- cold weather
- eating
- exercise
- stress
- emotions
what part of the history can differentiate between pericarditis and STEMI?
pericarditis - sharp pain
STEMI - dull pain
what is the most common cause of mitral stenosis?
rheumatic fever
Why do splinter haemorrhages form in endocarditis?
Septic emboli dislodge and block small blood vessels
What is the PRIMARY mechanism by which Glyceryl trinitrate (GTN) spray alleviates myocardial ischaemia in a patient with stable angina?
vasodilation of veins
which ECG abnormality can result in thrombus formation, which can embolise causing a stroke?
atrial fibrilation causes uncoordinated contractions which can result in stasis - resulting in thrombus formation
How do you calculated ejection fraction?
What is a normal ejection fraction?
(SV/EDV) x 100
Normal EF = 50% - 70%
Why are ace inhibitors given in heart failure?
Reduce angiotensin 2 formation
Reduce arteriolar and venous resistance
Why does right sided heart failure cause jugular vein pulsation and peripheral oedema?
Increase in right ventricular pressure
Increase pressure in systemic circulation
Increased central venous pressure causes jugular vein pulsation
Increase hydrostatic pressure in venule end of capillaries results in accumulation of interstitial fluid
what could increase the pulmonary capillary pressure?
mitral stenosis
this increases left atrial pressure which would increase pulmonary capillary pressure in lungs
On which side is the patients JVP measured?
Right side
If diastolic pressure falls what happens to pulse?
Pulse measures pulse pressure
If diastolic pressure drops pulse pressure increases
pulse is strong and bounding
where are baroreceptors located?
carotid sinus + aortic arch
What is responsible for setting the resting membrane potential in ventricular myocytes?
Permeability to potassium
What is the effect of severe hyperkalaemia on spread of action potentials through out myocardium?
Since resting membrane potential is set up by permeability to potassium ions, raising extra cellular potassium concentration makes the equilibrium potential (Ek) less negative
this inactivates Na+ channels and slows upstroke of action potential which slows conduction
What does calcium bind to in cardiac myocytes and in ventricular smooth muscle?
Cardiac myocytes = troponin C
Ventricular smooth muscle = calmodulin, the calcium calcmodulin complex activates myosin light chain kinase
Why does stable angina present with pain during exercise?
Blood flow through left coronary artery is compromised because diastole is shorter
What do different parts of the ECG represent?
P wave = depolarisation of atria
QRS = ventricular depolarisation
ST segment = time between depolarisation and repolarisation of ventricle
T wave = ventricular repolarisation
What drug should be given immediately in anaphylactic shock?
Adrenaline
what is the action of adrenaline upon cardiac muscle, skeletal muscle?
at physiological adrenaline levels = vasodilation (β2 receptors)
At pharmacological levels = vasoconstriction (α1 receptors)
how is vasomotor tone maintained?
the parasympathetic nervous system constantly releases a small amount of noradrenaline to cause vasoconstriction
why are statins not given to people with liver disease?
statins are liver toxic and cause even more liver damage
on an ECG lead why are leads II and aVR mirror images of each other?
view heart from opposite sides
if there are normal p waves followed by a QRS complex but the heart rate is <60 bpm is this sinus rhythm?
YES it is sinus bradychardia
if there are normal p waves followed by a QRS complex but the heart rate is <60 bpm is this sinus rhythm?
YES it is sinus bradychardia
what does a very tall R wave in leads V5 + V6 indicate?
left ventricular hypertrophy
what does a broad QRS complex on an ECG indicate?
escape rhythm where ventricles take over as pace maker
(dangerous if persists as it can result in ventricular fibrilation)
which ion channel is responsible for the slow pacemaker potential in cells of the SAN?
HCN channels
(current through these channels = funny current)
which ion channel is responsible for the upstroke of ventricular action potential?
voltage gated sodium channels
resting membrane potential in these cells is sufficiently negative to allow the voltage gated sodium channels to recover from the inactivation back to their resting state
into which structure do the cardiac veins drain?
coronary sinus
where are the different heart sounds heard?
aortic valve = right 2nd intercostal space
pulmonary valve = left 2nd intercostal space
mitral = mid clavicular line left 5th intercostal space
tricuspid = lower left sternal border 4th intercostal space
What is the impact of an increased in preload in a failing heart?
the underlying cause of heart failure decreases SV
so increased filling of heart has very little impact on increasing CO
instead sarcomeres stretch too much so actin and myosin no longer interact properly
can impair contractility and decrease CO = pulmonary congestion
what does a pathological Q wave represent in a STEMI?
Infarction is transmural
how is a wave of cardiac myocytes depolarisation moving towards an electrode detected on ECG?
upward deflection due to the detection that outside of cell is more negative than inside the cell
how is a wave of cardiac myocytes depolarisation moving away from the electrode detected on ECG?
downward deflection due to the detection that the outside of the cell is more negative than inside the cell
how is a wave of cardiac myocytes repolarisation moving towards an electrode detected on ECG?
downward deflection due to detection that the outside of the cell is more positive than inside the cell
how is a wave of cardiac myocytes repolarisation moving away from the electrode detected on ECG?
upward deflection due to detection that the outside of the cell is more positive than inside the cell
what happens to cerebral circulation in cushings reflex?
cushings reflex = raised intercranial pressure
increased pressure impairs blood flow to vasomotor control regions of brain stem
increased sympathetic vasomotor activity causes vasoconstriction
vasoconstriction forces blood against raised intercranial pressure which helps maintain arterial blood flow
what is the difference betwen oncotic and hydrostatic pressure in systemic vs pulmonary circulation?
hydrostatic pressure in systemic circulation > pulmonary circulation, however oncotic pressure of interstitial fluid is higher in pulmonary circulation so it makes up for this
plasma oncotic pressure is the same for both
how do capillaries at the base, level of heart, and apex of lung vary in upright position?
due to gravity greater hydrostatic pressure in most inferior vessels:
vessels at base of lung are normally distended
vessels at level of heart are continuously patent
vessels at apex are only open during systole, because this is only time pressure in apex increases
what is a saddle embolus?
a large embolus that straddles the bifurcation of an artery (usually pulmonary artery)
- what happens to heart rate in 3rd degree heart block?
- why is this change observed?
- bradychardia
- there is complete conduction block between the atria and ventircles so the ventricles depolarise at their own rate which is slower
