Cardiology Flashcards
(172 cards)
SAN is made of_____ cells with automaticity so they depolarise regularly causing localised activation and contraction __ ___ ____.
- pacemaker cells
- of the atria
SAN sits -
In sinus ryhthm, the p wave should be:
+ in lead __ and - in lead ___
- superior in the RA near the junction with the superior vena cave
- positive in lead II, negative in lead aVR
- SAN pulse goes through atria to AVN which lies in the
- what is the name of the tissue that separates both the atria and ventricles from eachother
- intra atrial septum
- the annulus fibrosis
What are the 2 reasons the annulus fibrosis is important
- prevents direct conduction from atria to ventricles so the atrial kick can supply filling (20%) to ventricles, esp important in tachycardias
- in v rapid intrinsic atrial rates e.g AF (~250bpm) its good AVN delays conduction down to ventricles so prevents VT/VF dangerous tachycardias.
Where is the ANV nodal delay seen on the ECG?
PR-interval indicates electrical stimulation starting at SAN, travelling through atria and AVN and about to travel down bundle of his
What may a prolonged or a short PR interval on ECG suggest?
- prolonged: delay/conduction disease at level of AVN
- short: accessory pathway allowing rapid conduction from atria to ventricles that bypasses the AVN
What artery supplied the SAN and ANV therefore which MI can affect these? May present clinically with _____ or ___
- the right coronory artery
- inferior MIs
- sinus bradycardias or heartblocks
From AVN where does the excitation pass? (detail)
- through annulus fibrosis
- through bundle of His
- divides into left (LV) and right bundle branches (RV)
- left bundle branch divides into left anterior and left posterior fasicles
The Q wave on an ecg identifies the wave of electicity passing through the ___
- in normal physiology this goes in the direction ___
- so in the lateral leads the q wave will be small ___ because
- interventricular septum
- from left to right
- small negative deflection as wave travels L -> R /away from those leads through the IV septrum
QRS should be less than:
1 reason qrs may be broad is ___
<0.12 seconds
Bundle branch block
Any of the conducting tissues of the heart can initiate heart rate e.g. __can be pacemaker cells but the further down the conduction system the heart rate is initiated by, the:
- ____ heart rate and the
- ___QRS will be
- e.g.(AVN-50bpm max, bundle of His, purkinje, myocardium-max 35bpm for example)
- slower the heart rate
- broader the QRS will be (myocyte to myocyte conduction is much slower)
Cardiac arrhythmia is __ occurs either when there is _ or _
- failure of sinus rhythm which can occur either when there is abnormal impulse formation
- abnormal impulse conduction
7step approach to rhythm analysis 1-how is pt clinically 2-is there any \_\_\_ activity present 3-what is the \_\_ rate 4-is the \_\_\_ rhythm regular or irregular 5-is the \_\_ \_\_ or \_\_\_ 6-is there any\_\_ activity present 7-how is the \_\_ and \_\_\_ activity \_\_\_
2-is there any ventricular _ activity present
3-what is the ventricular rate
4-is the ventricular rhythm regular or irregular
5-is the QRS Broad or Narrow__
6-is there any_Atrial activity present
7-how is the _Atrial _ and _ventricular__ activity __related
7step approach to rhythm analysis
1-how is pt clinically
What adverse signs should you be looking for?
- ABCDE
- ischaemia? - on ecg, or chest pain
- syncope? or reduced GCS
- shock? or low BP
- heart failure? or pulmonary oedema or high O2 requirement
7step approach to rhythm analysis
2-is there any ventricular activity present.
If no, why not and what can you do?
- asystole , check pts pulse, if no pulse, start CPR
- if flat-lining, check the ECG leads incase misplaced
7step approach to rhythm analysis
- Is the ventricular rate regular or irregular?
If bradycardia and irregularly irregular with no p waves, how could AF have caused this
-SLOW AF: irregular atrial depolarisation occurs at rapid rates, but whether ventricles are activated depends on AVN conduction, if there is conduction disease at this level, the ventricular activity will always be irregularly irregular
7step approach to rhythm analysis
- Is the ventricular rate regular or irregular?
If its regular, and bradycardia, and broad QRS and no p waves, what could have happened
- AF and complete heart block as there is a complete dissociation between the atria and ventricles
- if in AF and was conducting, the ventricular activity would be irregularly irregular so the fact the ventricular activity is regular, shows pt is in complete heart block.
- is the QRS Broad_ or _Narrow? Helps identify if the impulse is __ or __ in origin
-ventricular or supraventricular
If the QRS is narrow, we know, although it has a supraventricular origin, it is using what?
the normal conduction fibres of heart to produce its narrow complex.
If there is the presence of a ventricular rhythm it means the rhythm is arising away from the ____ or below the level of the ____
and it causes a broad QRS as there is ____
- away from the conducting system of the heart or
- below level of the bundle of his
- broad complex as there is slower myocyte to myocyte contraction through the ventricles
If you have a supraventricular rhythm like AF but you also have a heart block (e.g. BBB) what rhythm and QRS may result?
a Broad complex tachycardia
- Is there atrial activity present? What is it like? Options could be:
- are they p waves (sinus tachycardia)
- fibrillation waves (AF)
- flutter waves (atrial flutter)
Disease at SAN can cause sinus bradycardia, name 5 pathological causes
- IHD, MI
- hypothyroidism
- hypothermia
- electrolyte..e.g high K+, high Ca2+
- raised ICP
- sick sinus syndrome
What is sick sinus syndrome? Mostly caused by idiopathic fibrosis of SAN (also drugs, MI, amyloidosis…)
Dysfunction at the level of the SAN resulting in impaired generation and conduction of impulses