Cardiology Flashcards
(38 cards)
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…
