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57 Cards in this Set
- Front
- Back
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What are the intrinsic rates of the following pacemakers:
- SA node - AV node - Bundle of His - Purkinje fibres |
- SA node = 80bpm
- AV node = 60 bpm - Bundle of His = 40bpm - Purkinje fibres = 20bpm |
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what is the normal av. HR?
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70 bpm
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T/F: atrial contraction should precede ventricular contraction
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TRUE
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where does electrical activity in the heart normally arise?
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SA node
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what causes current flow in the atria?
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Voltage gradient.
this is caused by part of the atria being polarised at resting potential (-80mV) and another part being depolarised to the peak of the AP (+30mV) |
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What is the definition of cardiac axis?
What range is considered normal? |
The vector sum of all current flow across the heart i.e. the general direction of the heart's depolarisation wavefront
Normal = -30 to +90 degrees |
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T/F: electrode pairs along the line of that axis will see the smallest voltage changes
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FALSE!
electrode pairs ALONG the line of that axis will see the LARGEST voltage changes those perpendicular to the axis will record no voltage difference |
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What does the PQ interval represent?
[What does it mean when it is elongated or irregular? ] |
The time taken for conduction from the SAN
1. across the atria 2. through the AV node 3. through fast conduction system of ventricles to ventricular mm. [Elongated or irregular --> something wrong with conduction] |
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What does QT interval represent?
When might it get shorter? |
duration of ventricular AP
shorter during exercise |
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When might you get left axis deviation?
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LVH
Pregnancy (normal) LBBB Congenital heart disease (e.g. atrial septal defect) Emphysema Hyperkalaemia |
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When might you get right axis deviation?
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RVH
RBBB |
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When is right axis deviation deemed normal and why?
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In children - because their R heart is more predominant than in adults
Also in Dextrocardia |
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Who is a baus?
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Kate
[10 points for this one] |
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Who loves vag?
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Eleanor
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Who poos out of their vag?
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Eleanor
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Who needs to take it easy peasy?
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Japanesie
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Finish this sentence:
"I think I'm turning _____" |
JAPANESE!!!!
I really think so |
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What 4 factors could lead to oedema?
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1. Incr. hydrostatic P
[Na+, H20 retention in HF, steroid OD] 2. Decr. colloid osmotic P [Decr. serum albumin - due to malnutrition, malabsorption, renal protein loss, liver disease i.e. failure to synthesise] 3. Blockage of lymphatics i.e. drainage 4. Incr. permeability [such as in allergic rxn - histamine] |
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What is the mean hydrostatic pressure in the capillaries ?
Where is it higher? |
25mmHg
Higher in arterial end cf. venous end |
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what is the hydrostatic pressure in the interstitial space
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zero
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what attracts fluid into a capillary?
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proteins i.e. colloid osmotic pressure (approx 20mmHg)
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what is the most common cardiac arrythmia? what is the prevalence?
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AF
2-5% of over 60s have AF |
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AF has important associations with which conditions?
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Mitral stenosis
Hypertension Ischaemic heart disease thyrotoxicosis cardiomyopathy |
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T/F: any heart disease can cause AF
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true- it can also be idiopathic
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What causes AF?
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caused by multiple wavelets of re-entry. need approx 6 wavelets for sustained AF
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what is the mechanism of AF in heart disease ?
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Probably:
High atrial pressures --> stretch atria --> atrial damage --> fibrosis --> promotes development of re-entrant circuits |
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T/F: ventricles contract regularly in AF?
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false - because only a proportion of the stimulations from the atria get through the AVN
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In untreated AF, what is the HR?
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150-200bpm (irregular)
NB: the fibrillation waves may have a frequency of 350-600bpm - they just don't all get through to ventricle |
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two major complications of AF
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embolism
heart failure |
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most common symptom of AF
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rapid, irregular palpitations
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Signs of AF
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Rapid, irregularly irregular pulse
Pulse deficit |
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what is pulse deficit?
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when pulse rate significantly lower than HR (as in AF)
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How do you diagnose AF? What do you see?
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ECG
No P waves Fibrillation waves (finely undulating baseline) Irregular QRS complexes |
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Why does embolism occur in AF?
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feeble atrial contraction --> pockets of stasis (esp in LA appendage) --> promotes thrombosis --> can detach and lodge in systemic circulation
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drug treatment of AF?
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1. control ventricular rate i.e. increase block in AVN
[digoxin, verapamil, beta blockers] 2. Revert AF [sotalol, amiodarone, flecanide] |
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how treat AF?
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1. treat cause e.g. thyrotoxicosis
2. drug treatment to revert arrhythmia and control ventricular rate 3. DC cardioversion |
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T/F: those with AF and NO HEART DISEASE do NOT have increased risk of stroke
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True (according to learning topics)
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those with AF and rheumatic valve disease, by how much does the incidence of stroke increase?
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15-20x
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Risk of serious thromboembolism in patients with AF is __% per year ?
By how much does warfarin decrease this risk? |
5% per year
Warfarin decr. to 1% |
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T/F: patients with lone AF are not given warfarin
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TRUE
warfarin carries its own risks of incr. bleeding |
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T/F: aspirin is just as effective as warfarin at decreasing risk of thromboembolism in patients with AF
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false - only 25-50% as effective as warfarin
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what 'curative' procedures can be performed to control AF?
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1. Maze procedure (most effective) - create lines of block in atria so re-entrant circuits can't develop --> not commonly done
2. Catheter ablation techniques --> haven't been proven effective |
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What must be done following AV nodal destruction via catheter ablation ?
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1. MUST insert PACEMAKER
because of resulting bradycardia 2. MUST ANTICOAGULATE as the atria are still fibrillating |
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what is the only organ to not have increased blood flow during pregnancy?
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brain
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T/F: a high resistance vascular network develops in uterus during pregnancy
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false - low resistance
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in pregnancy:
kidney flow incr. by __ % skin flow incr. by __ % liver flow incr. by __ % plasma volume incr. by __% red cell mass incr. by __% |
kidney flow incr. by 60 %
skin flow incr. by 50 % liver flow incr. by 50 % plasma volume incr. by 40% red cell mass incr. by 20% |
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why is there an increase in gut blood flow in pregnancy?
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to increase nutrient absorption
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why is there an increase in blood flow to breast in pregnancy?
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ensure breasts are developed - ready for feeding infant
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why are women prone to fainting during pregnancy?
When is this most apparent? |
progesterone induced vasodilation --> low BP
Middle trimester = lowest BP because vasodilation is maximum |
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what induces plasma volume increase in pregnancy?
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induced by aldosterone
(increased renin secretion from both kidney and uterus) |
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why do you get physiological anaemia in pregnancy?
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because plasma volume incr. by 40% and red cell mass only by 20% (i.e. increase is smaller - so red cells are diluted)
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pregnancy:
why does vasodilation not induce a MASSIVE fall in BP ? |
because incr. blood volume, also incr. CO (mainly due to incr. HR)
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pregnancy:
cardiac reserve increases or decreases? why? |
cardiac reserve = ability to incr. CO above normal level
DECREASES because increased plasma vol, HR, SV |
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what might make pregnant women prone to CHF?
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if they have abnormal heart, or if they are treated with drugs/fluids that speed up HR, drop BP or incr. circulating volume
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right or left axis deviation in pregnancy? why ?
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Learning topics say right axis deviation.
EVERYWHERE ELSE SAYS LEFT AXIS DEVIATION!!!!! Both give same reason - i.e. upward pressure on the diaphragm |
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JVP up or down in pregnancy? why?
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up
increase intravascular volume |
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when is raised JVP conisdered an unreliable sign of right sided heart pressures in pregnancy?
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20 weeks onwards
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