Cardiology Flashcards
What is an ECG?
An electrocardiogram is a representation of the electrical events of the cardiac cycle.
What is the standard ECG callibration?
25mm/s paper speed
0.1 mV/mm voltage
What factors modulate the rate of depolarisation of the SAN?
autonomic tone (parasymp and symp input) stretch temperature hypoxia blood pH hormonal influences (tri-iodothyronine and serotonin)
What is the significance of the refractory phase in myocyte action potential?
It prevents early reactivation of the myocytes and directly determines the strength of the contraction.
Where is the SAN located?
It lies in the lateral and epicardial aspects of the junction between the superior vena cava and right atrium.
Where is the AVN located?
It lies beneath the right endocardium within the lower interatrial septum.
What three factors describe the contractile function of cardiac tissue?
- the velocity of muscle contraction
- the load that is moved by the contracting muscle
- the extent to which the muscle is stretched before contracting
What does Starling’s law of the heart state?
The law states that the stroke volume of the heart increases in response to an increase in the volume of blood in the ventricles, before contraction, when all other factors remain constant.
Why has low molecular weight heparin replaced unfractionated heparin as anticoagulation treatment?
more effective
does not require monitoring
less risk of bleeding
What is the target INR?
2.5 (2-3)
Name some beta blockers.
propranolol, atenolol, bisoprolol
what conditions can hypertension lead to?
stroke mi heart failure chronic renal disease cognitive decline premature death
what does hypertension increase the risk of?
atrial fibrillation
increased independent stroke risk
What are the clinical parameters for suspected hypertension? What is the next step?
140/90 or higher
people with suspected hypertension are offered ambulatory blood pressure monitoring (ABPM) which monitors it over 24 hours.
Whatare the main clinical inications for ACEIS?
hypertension
heart failure
diabetic nephropahty
Give examples of ACEIs?
ramipril
etc
What are the main adverse effects of ACEIs?
related to reduced angiotensin II formation:
hypotension
acute renal failure
hyperkalaemia
teratogenic effects in pregnancy
related to increased kinin production:
cough
rash
anaphylactoid formation
What are the main clinical indications for ARB?
hypertension
diabetic nephropathy
heart failure (when ACEIs contraindicated)
What are the main adverse effects of ARBs?
symptomatic hypotension (hypovolaemic patients) hyperkalaemia potential for renal dysfunction rash angio-oedema
contraindicated in pregnancy
What are the main clinical indications for calcium channel blockers?
hypertension
ischaemic heart disease - angina
arrhythmia (tachycardia)
What type of channels do CCBs act on?
L-type (long-acting) CC
What are the three types of CCBs?
dihydropyridines
phenyl….
What are the adverse effects of CCBs?
due to peripheral vasodilation (mainly dihydropyridines as heart increases rate and pressure to match dilation) flushing headache oedema palpitations
due to negatively ….
What are the main clinical indications for beta-adrenoceptor blockers?
hypertension etc…
What are the main adverse effects of beta-adrenoceptor blockers?
fatigue
headache
sleep disturbance/nightmares
bradycardia
hypotension
cold peripheries
erectile dysfunction
What previous conditions can beta blocker use worsen?
asthma or COPD
PVD- claudication or Raynaud’s
heart failure - if given in standard dose or acutely
What are the main clinical indications for diuretic use?
hypertension
heart failure
What are the different classes of diuretics?
thiazides and related drugs (distal tubule)
Give examples of thiazide diuretics.
bendroflumethiazide
hydrochlorothiazide
chlorthalidone
give examples of loop diuretics.
furosemide
bumetanide
Give examples of potassium-sparing diuretics.
spironolactone
What are the main adverse effects of diuretics?
hypovolaemia
hypotension (boh mainly loop diuretics)
hypokalaemia
hyponatraemia
How can you relieve symptoms in congestive heart failure?
loop diuretics
What does the disease influencing therapy of CHF involve?
neurohumoral blockade-
inhibition of RAAS and SNS
What are the main effects of cardiac natriuretic peptides?
….
What are nitrates mainly used for?
ischaemic heart disease - angina
heart failure
What are the adverse effects of amiodarone?
QT prolongation polymorphic ventricular tachycardia interstitial pneumonitis abnormal liver function hyperthyroidism/hypothyroidism sun sensitivity slate grey skin discolouration corneal microdeposits optic neuropathy
multiple drug interactions - especially warfarin - amiodarone displaces warfarin from its binding site to blood proteins causing a lot of free warfarin which will cause over-anticoagulation and bleed to death
very large volume of distribution so it gets everywhere
How would you medically manage a patient with atrial fibrillation?
- tx underlying cause: alcohol, thyroid disease, hypertension, valve disease, heart failure etc
- rate control: beta blockers, calcium channel blockers, digoxin
- return sinus rhythm: electrical or pharmacological (amiodarone) cardioversion
- Maintain sinus rhythm: sotalol, amiodarone
