WEEK 7 - palpitations Flashcards
where does the pericardial cavity sit?
between the parietal and visceral layers of the serous pericardium
Cardiomyocyte ________ in unison in order to provide effective pump action to ensure adequate blood _________ of the organs and tissues. Cardiomyocyte make up the bulk of the volume of the heart but constitute only ______ of the total cell number.
Intercalated discs (gap junction) provide an electrical junction from one cell to the next. They transmit _______ currents from one cell to the next. Intercalated discs are made up of 6 hollow tubes (________) that provides an intercellular gap enabling the ___________ to act as an electrically continuous sheet and all myocytes to be activated simultaneously.
Intercalated discs (desmosomes) provide a structural attachment from one cell to the next. They ‘glue’ cells together. Glycoproteins called _________ span the 25nm gap between the cell membranes, and ______ forms the intermediate filaments.
Transverse tubules (t-tubules) are invaginations of the cell membrane which run into the _______ of the cell. They transmit the electrical stimulus rapidly into the interior of the cell. Transverse tubules promote the synchronous activation of the whole depth of the cell despite the fact that the signal to contract is relayed across the external membrane.
- contract
- perfusion
- 30-40%
- ionic
- connexon
- myocardium
- cadherins
- desmin
- interior
inflow of what depolarises the membrane and causes a rise in membrane voltage?
Na+
rapid outflow of what returns the membrane potential to its resting potential?
K+
Lead I detects electrical activity from which aspect of the heart?
left lateral
Lead aVR detects electrical activity from which aspect of the heart?
right atrium
Lead V6 detects electrical activity from which aspect of the heart?
left ventricle
what does each aspect of an ecg look at?
what are narrow complex vs broad complex tachycardias?
- Narrow: Atrial fibrillation, Supraventricular tachycardia eg atrial flutter
- Broad: Ventricular fibrillation
what 3 things could you find on examination with thyrotoxicosis?
goitre, tremor and exophthalmos
what 2 things could you find on examination with anaemia?
pallor of creases, conjunctivae
Flip-flopping – the palpitations are thought to be caused by _____ ______ such as supraventricular or ventricular premature contractions. The flip-flop sensation is thought to result from the forceful contraction following the pause and the sensation that the heart is stopped results from the pause.
extra systoles
Rapid fluttering – result from a sustained ventricular or supraventricular arrhythmia. Furthermore, the sudden cessation of this arrythmia can suggest ________ __________ __________. This is further supported if the patient can stop the palpitations by using _________ manoeuvres.
paroxysmal supraventricular tachycardia
Valsalva
The rhythm of the palpitations may indicate the aetiology of the palpitations (irregularly irregular palpitations indicate _____ _______ as a source of the palpitations). An irregular pounding sensation in the neck can be caused by ____________ _________, and the subsequent atria are contracting against a closed tricuspid and mitral valves, thereby producing _______ _ _____.
- atrial fibrillation
- atrioventricular dissociation
- cannon A waves
Palpitations induced by exercise could be suggestive of _______________, ___________ or ____________.
cardiomyopathy, ischemia or channelopathies
Palpitations can occur during times of catecholamine excess, such as during exercise or at times of stress. The cause of the palpitations during these conditions is often a sustained __________ tachycardia or ____________ ____________. ____________ tachycardias can also be induced at the termination of exercise when the withdrawal of catecholamines is coupled with a surge in the _____ tone.
Many psychiatric conditions can result in palpitations including depression, generalized anxiety disorder, panic attacks, and somatization.
- supraventricular
- ventricular tachyarrhythmia
- supraventricular
- vagal
according to NICE, if the cause of the palpitations remains unclear, what should you do if…..
- If symptoms are relatively infrequent (less than once a week) and last for an hour or more
- If symptoms are short lived but frequent
- If symptoms are short lived and infrequent
If the cause of the palpitations remains unclear:
If symptoms are relatively infrequent (less than once a week) and last for an hour or more, advise the person to attend an Accident and Emergency department, or their GP surgery, for an electrocardiogram (ECG) during the next episode. Provide a letter to be given to the healthcare professional requesting an ECG immediately on presentation during an episode.
If symptoms are short-lived, arrange ambulatory monitoring in primary care if available, or refer to cardiology. The type of monitoring required is dependent on the frequency and duration of symptoms:
If symptoms are short lived but frequent (for example, daily), a 24-hour or 48-hour Holter monitor is appropriate.
If symptoms are short lived and infrequent (for example, less than once a week), a self-activated recorder or an event monitor is appropriate.
what are palpitations?
Palpitations are defined as rapid pulsations or abnormal rapid or irregular beating of the heart. They are common and non-specific. The cause of palpitations could be benign or more life threatening
how can the causes of palpitations be defined according to their underlying pathogenesis?
- High output states: Anaemia or pregnancy
- Structural cardiac causes: valvular heart disease, ischaemic heart disease, hypertension
- Catecholamine excess: high caffeine, illicit drugs, stress, anxiety
what is an arrhythmia?
an abnormality of the heart’s rhythm. It may beat too slowly, too quickly, or irregularly. These abnormalities range from a minor inconvenience or discomfort to a potentially fatal problem. Arrhythmias or heart rhythm problems are experienced by more than 2 million people in the UK.
bradycardia = <__bpm
tachycardia = >__bpm
- 60
- 100
what can cause bradycardias?
occur when depolarisation FAILS to initiate or conduct properly
- SAN disease
- heart block (AVN, His-bundle)
what can cause tachycardias?
occur when there is ABNORMAL depolarisation occurring in the heart
- enhanced automaticity
- reentry
what is SA node disease and what are the various forms?
when the SA node fails to act as the ‘pacemaker’
- sinus bradycardia
- sinus pause
- sinoatrial exit block (heart block)
what does this show?
sinus bradycardia
Sinus bradycardia occurs on an ECG when there is a normal upright P wave in lead II ― sinus P wave ― preceding every QRS complex with a ventricular rate of less than 60 beats per minute.
Many normal causes like in athletes or when asleep
what does this show? describe the condition
sinus pause
- Sinus pause describes a condition where the SA node fails to generate an electrical impulse for what is generally a brief period of time.
- Patients who have sinus pauses may complain of missed or skipped beats, flutters, palpitations, hard beats or may feel faint, dizzy or lightheaded or experience a syncopal episode (passing out). Frequent pauses would heighten these symptoms. This is a result of patients actually missing or dropping beats. Obviously, if the heart misses a beat, blood does not flow during that time period resulting in a lack of oxygen or perfusion throughout the body.
- Treatment may involve the use of medications or the use of a temporary or permanent pacemaker.
what does this show? describe
sinoatrial exit block (heart block)
During sino-atrial exit block, the depolarizations that occur in the sinus node cannot leave the node towards the atria. They are blocked. On the ECG this is expressed as a pause. SA exit block can be distinguished from sinusarrest because the pause in SA exit block is a multiple of the P-P interval that preceded the pause.
what is first degree heart block?
slow conduction through AV node
what are the 2 types of 2nd degree heart block?
- Wenckebach or Mobitz type I — Av conduction becomes slower and slower until it misses a beat
- Mobitz type II — fixed block - usually 2:1
what is 3rd degree heart block?
complete heart block — no conduction to the ventricles
an escape pacemaker takes over from the His-bundle/bundle branch
what does this show?
2nd degree heart block type I
what does this show?
3rd degree heart block
what does this show?
2nd degree heart block type II
what does this show?
1st degree heart block
how to remember heart block mnemonic
what is automaticity?
an area of myocardial cells depolarise faster than the SA node. this may be atrial or ventricular issue. most occur at a single ‘focal’ site
what is reentry?
an electrical pathway that is not supposed to be there, connecting 2 areas that should not be connected. abnormal electrical connections can be congenital, or they can form because of heart disease. if such a connection exists, it can form an electrical circuit
what are the 2 types of tachycardia?
narrow complex (SVT) and broad complex (VT):
- supraventricular tachycardia (SVT) is a heart condition where the heart suddenly beats much faster than normal. this type of tachycardia originates from faulty electrical impulses in the upper part of the heart, rather than from the ventricles
- ventricular tachycardia (VT) is defined as a sequence of three or more ventricular beats. the frequency must be higher than 100bpm, mostly it is 110-250 bpm
(AVNRT = atrioventricular nodal reentrant tachycardia)
what does this show?
atrial flutter
what does this show?
atrial tachycardia
what does this show?
atrio-ventricular reentry tachycardia (AVRT)
what does this show?
AF
what does this show?
AVNRT
what does this show?
ventricular fibrillation
what does this show?
ventricular tachycardia
CHA2DS2VASc, ORBIT and HASBLED
what are the main factors used to help decide between a rate versus rhythm control strategy for patients with AF?
what does this show?
SVT
The rhythm is a regular narrow complex tachycardia with a ventricular rate of ~180 bpm. There are no clear p waves and the QRS is narrow (less than 120 ms or <3 small squares).
what does this ecg show?
Sinus tachycardia with a single premature ventricular ectopic/complex (PVC).
The rhythm is sinus as there are clear normal p waves preceding each QRS beat (aside from the ventricular ectopic) and the PR interval is normal (120-200 ms or between 3-5 small squares). The ventricular rate is about 150 bpm. When counting from left to right beat 7 is broad (i.e., >120 ms or > 3 small squares) and different to the sinus rhythm complexes. It is occurring slightly prematurely. The last 4 beats are sinus rhythm.
what is monomorphic VT commonly due to?
re-entry circuits within scar in patients with structural heart disease
what does this mean
idk
digoxin and warfarin
A patient with AF of longer than 48 h duration is at risk of thromboembolism after cardioversion. Unless the patient is severely compromised, it is standard practice to prescribe anticoagulation to the patient with warfarin for a month before attempting elective cardioversion. During that time the ventricular rate is controlled by prescribing digoxin.
DC shock and heparin
In this case immediate DC shock is indicated because the patient is severely compromised. The administration of heparin decreases but does not abolish the risk of thromboembolism after cardioversion.
do not prescribe anything
Her CHADSVASC score is 1 due to her being female. With no other risk factors, NICE recommend not to issue any form of anticoagulation. A male with a score of 1 should be considered for anticoagulation. For AF, treatment would be lifelong, if started, in anyone with a score of 2 or above.
class 3
Amiodarone has class I, II, III and IV actions but is used clinically for its class III actions. Class III drugs act as a potassium blocker, which prolong the plateau phase of the cardiac action potential and increase the absolute refractory period. As a consequence, they also prolong the Q–T interval.
Amiodarone is the drug of choice to treat VT. When it is used chronically it has a number of adverse effects but these are not an issue in the acute scenario. These adverse effects include bradycardia, pulmonary fibrosis, hepatic fibrosis, corneal microdeposits (regress if drug is stopped), photosensitive rash and thyroid dysfunction.
Torsades de Pointes
This is torsades de points, which will often degenerate to ventricular fibrillation leading to cardiac arrest. Causes include drugs, electrolyte disturbance and congenital long Q–T syndrome. Conventional anti-arrhythmic will make this condition worse. The treatment of choice is intravenous magnesium sulphate and ventricular pacing at a high rate.
