Week 3: Cardiac 2 Flashcards
What does electrical conduction do?
Coordinates the contraction of the heart muscle to effectively pump blood and nutrients around the body.
What is an ECG?
assessment of the magnitude and direction of he electrical currents of the heart.
Measures the depolarisation and repolarisation of the cardiac cells.
What does the phrase ‘time is myocardium’ refer to?
This refers to the increasing damage that occurs to the heart muscle the longer someone has to wait for diagnosis and treatment.
An ECG must be obtained in a timley manner.
List the 6 position of an ECG
V1= 4 intercostal space V2= 4 intercostal space V3= between v2 and v4 V4= 5 IC space (mid clavicular) V5= 5 IC anterior axillary line V5= 5 IC anterior mid- axillary line
Describe a sinus rhythm
Normal rhythm
- generated by the SA node
- rate= 60-100 hence why a normal HR is 60-100 bpm
Rate: 60-100 bpm P wave: present, upright PR interval: 0.12-0.2s QRS complex: is proceeded by a normal p wave, < 0.12s T wave: present, upright Mechanical contraction: present
What characterises acute coronary syndrome?
a reducing in blood supply to the cardiac muscle
or
total occlusion
Which are the ost common vessels for a MCI to occur in?
- Left anterior descending artery (supplies front and septum of the heart)
- most common artery effected in heart attacks - Right coronary artery
- Left circumflex
What are some ECG changes in ACS?
When caused by unstable angina
Unstable angina= Normal ECG or T wave depression
What is a sub endocardial infarction
when an occlusion prevents blood flow to the lower regions of myocardial tissue.
Define a Non stemi
and describe what it may apear as on on ECG
Non stemi is a Non-ST-Elevation Myocardial Infarction (NSTEMI)
myocardial ischaemia occurs due to an occlusion of one or more coronary arteries. This causes myocardial injury or necrosis and can be diagnosed by abnormal cardiac biomarkers and ECG
appear as nothing
- invered T wave
- decreased ST
- no progression to Q wave
Define stemi and what it may appear as on an ECG
ST-Elevation Myocardial Infarction
- elevated ST wave
- progression to deep Q wave
Define sinus tachycardia.
Explain the cause, an example, effects on the heart and treatments.
Notes the
- P wave
- PR interval
- QRS complex
- Rate
- T wave
- Mechanical contraction
a sinus rhythm with a rate ≥100 beats/min is known as sinus tachycardia (ST).
P wave: present, upright PR interval: 0.12-0.2ms QRS complex: is preceeded by a normal p wave, < 120ms Rate: >100 bpm T wave: present, upright Mechanical contraction: present
Cause: increased sympathetic response and decreased parasympathetic response to meet increased metabolic needs.
For example, a young adult may experience a heart rate of close to 200 beats/min during exercise.
Effects: - decreased filling times - decreased mean arterial pressure - increased myocardial demand.
Treatments= rest, onygen and calcium channel blockers
Define sinus Bradicardia.
Explain the cause, an example, effects on the heart and treatments
Notes the
- P wave
- PR interval
- QRS complex
- Rate
- T wave
- Mechanical contraction
A sinus rhythm with a heart rate of less than 60 beats/min is known as sinus bradycardia (SB).
* this is contextual depending on people’s abilities e.g. athlete sinus bradycardia may be less then 40bpm
P wave: present, upright PR interval: 0.12-0.2ms QRS complex: is preceeded by a normal p wave, < 120ms Rate: <60bpm T wave: present, upright Mechanical contraction: present
Effects:
- increased preload
- decreased mean arterial pressure.
Treatment:
- treating the cause
- sympathomimetic
- anticholinergics
- pacemakers
Describe atrial fibrillation (AF)
the result of abnormal electrical pathways in the atria and often results in an irregularly irregular ventricular contraction.
- most common arrhymia
Define an arrhythmia and give examples
a fault in the heart’s electrical system, which affects your heart’s pumping rhythm. The abnormal electrical activity makes the heart muscle beat too fast, slow or in an irregular way.
- atrial fibrillation
What conditions may have atrial fibrillation as a clinical manifestation?
- myocardial ischaemia
- heart failure
- electrolyte disturbances
- thyroid dysfunction
- hypovolaemia
- postoperative complication
What are some types of atrial fibrillation?
Occasional (paroxysmal): symptoms come and go, usually lasting for a few minutes to hours. May need treatment.
Persistent: lasts longer than a week; can become permanent. Treatment can include cardioversion or medications
Permanent: heart rhythm cannot be restored, requires medication to minimise the effects and complications.
What are some causes of atrial fibrillation?
Can be caused by a range of pathophysiological mechanisms.
- Excess catecholamines: adrenaline infusion, stress, thyrotoxicosis
- Increased atrial automaticity: alcohol, caffeine, myocarditis, eletrolyte derangement
- Atrial distention: pulmonary hypertension, septal defects, valvular disease
- Abnormality of the conducting system: congential cardiac disease, ischaemic heart disease, hypothermia
What are some complications of atrial fibrillation?
Adverse effects of haemodynamics:
- Loss of the “atrial kick”, this can represent a loss of up to 20% of ventricular filling and therefore cardiac output
- With increased ventricular rates, there is a decrease in diastolic filling time
Atrial thrombus formation
- Significant increased risk of a systemic embolism (including stroke) and pulmonary embolism
Heart failure
Explain atrial fibrillation on an ECG and the pathophysiology behind what can be observed?
AF is characteried by no discernible P wave as the electrical activity from the SA node to the AV node is irregular.
The abnormal erratic and disorganised electrical rhythm creates a “quivering” of the atria which is a classic presentation of AF.
- Multiple re-entry circuits developing in the atria causing chaotic activity
- The SA node is no longer the pacemaker
- The AV node is bombarded by rapid atrial impulses resulting in an irregular response
- AF can occur suddenly (paroxysmal) or can persist as a chronic arrhythmia
Assessing and analysing the presence or absence of a P-wave is best seen in lead II.
What are some clinical manifestations of AF?
- altered conscious state
- irregular pulse
- palpitations
- chest pain
- Dizziness/syncope
- hypotension
- diaphoresis (sweating)
- Pallor
How is AF assessed?
- irregular HR
- ECG
How can AF/potential AF be assessed?
- Electrocardiogram (ECG)
- Holter monitor
- Echocardiogram
- Blood tests, e.g. thyroid
- Stress test
- Chest X-ray
What is the treatment for AF?
Medication
- Anti-arrhythmic agents to normalise the heart’s rhythm
- Beta-blockers, some calcium channel blockers and/or digoxin to slow the heart rate
- Anticoagulation medications may be prescribed to reduce the risk of stroke
Electrical cardioversion (synchronised cardioversion) - an electrical shock to attempt to restore the heart’s normal electrical rhythm
Pharmacological cardioversion – Medication to restore the heart’s normal electrical rhythm in a short period of time.
Catheter ablation - a procedure that utilises a catheter to ablate any areas that may be causing the arrthymia
Pacemaker - can electrically stimulate the heart to maintain a regular rhythm
Management of other medical conditions - hypertension, cardiac failure, heart valve disease and diabetes mellitus
Management of obstructive sleep apnoea
Avoiding potenial triggers like stress, caffeine, dehydration
Lifestyle: Maintain healthy weight, increase physical activity, moderate-to-no alcohol intake and cease smoking
Summarise AF in terms of the
- P wave
- QRS complex
- Rate
- Mechanical contraction
- Pathophysioloogy
- Causes
- Treatment
P wave: rate usually > 300 and not identifiable
QRS complex: could be normal or wide
Rate: usually variable with an irregular rhythm
Mechanical contraction: present
Pathophysiology: impulse does not originate in the SA but elsewhere in the atria and leads to the atria quivering
Causes: Electrical disturbances, hypoxia, cell membrane disturbances
Treatment: Treat the underlying cause, pharmacology treatment may include digoxin
Describe what Af looks like on a ECG
Irregularly irregu.ar
- no distinct P wave
What are some risk factors of AF?
- diseased atrial tissue
- age
- inflammation
- atrial enlargement (due to certain diseases)
- hormonal abnormalities
- years if alcohol abuse
What are people with AF more at risk of any why?
stroke
- as bllod in atria becomes stagnant when it is spasming.
It then clots and travels to the brain.
Explain Ventricular tachycardia by mentioning the;
- P wave
- QRS complex
- Rate
- Mechanical contraction
- Pathophysioloogy
- Causes
- Treatment
P wave: absent or independent of the QRS
QRS complex: very broad
Rate: >180 bpm
Mechanical contraction: can have a pulse or no cardiac output.
Pathophysiology: impulse originates in the ventricles outside of the normal conduction system.
Causes: Aging, anaesthesia (particularly induction), ischaemic heart disease, cardiomyopathy, congential heart conditions, imbalance of electrolytes, medication side effects and the use of drugs.
Treatment: No cardiac output or pulse requires immediate basic life support including CPR. Pharmacology is aimed at changing the thresholds and refractory periods.
Explain Ventricular fibrillation by mentioning the;
- P wave
- QRS complex
- Rate
- Mechanical contraction
- Pathophysioloogy
- Causes
- Treatment
P wave: absent, not identifiable
QRS complex: not identifiable
Rate: 150-500/minute; the ventricles are contracting in a rapid, uncoordinated manner, similar to quivering.
Mechanical contraction: no cardiac output
Pathophysiology: impulse originates in the ventricles outside of the normal conduction system.
Causes: aging, anaesthesia (particularly induction), ischaemic heart disease, cardiomyopathy, congential heart conditions, cardiac tamponade, myocarditis, aortic stenosis, aortic dissection, tension pneumothorax, pulmonary embolism, hypothermia, CVA, imbalance of electrolytes, medication side effects and the use of drugs are some of the causes.
Treatment: No cardiac output or pulse, requires immediate basic life support including CPR. Pharmaocology is aimed at changing the thresholds and refractory periods.
