Cardiology Flashcards
What does the P wave represent on ECG
What does the PR interval represent electrically and physiologically and how long is this?
Atrial depolarisation
The atria contracts during the PR interval, the PR interval is the time taken for electrical activity to spread from the SA node to the AV node
This is from the start of the P wave to the start of the QRS complex
120-220ms, 3-5 small squares
What does the QRS complex on the ECG represent?
How long does this take?
ventricular depolarisation
120ms 3 small squares
What does the ST segment on the ECG represent?
end of the S wave to the start of the T wave
ventricular contraction
What does the T wave represent?
Venticular repolarisation
what is the QT interval and how long should this be?
start of the Q wave to the end of the T wave
400-440ms prolonged is more than 450
What causes the first heart sound (S1)
- what would cause this to be loud
- what would cause this to be soft
- Closure of mitral and tricuspid valves
- Soft if long PR or mitral regurgitation
- Loud in mitral stenosis
- Variable intensity in complete heart block
What causes the second heart sound S2?
caused by the closure of the aortic valve (A2) closely followed by that of the pulmonary valve
(P2)
What would cause a loud S2?
Causes of a loud S2
• Hypertension: systemic (loud A2) or pulmonary (loud P2)
• Hyperdynamic states
• Atrial septal defect without pulmonary hypertension
What would cause a soft S2?
Causes of a soft S2
• Aortic stenosis
What would cause a fixed split S2?
What would cause a widely split s2?
Causes of fixed split S2
• Atrial septal defect
Causes of a widely split S2 • Deep inspiration • RBBB • Pulmonary stenosis • Severe mitral regurgitation
what would Cause a reversed (paradoxical) split S2 (P2 occurs before A2)?
Causes of a reversed (paradoxical) split S2 (P2 occurs before A2) • LBBB • Severe aortic stenosis • Right ventricular pacing • WPW type B (causes early P2) • Patent ductus arteriosus
What is S3? what is this caused by?
- Caused by diastolic filling of the ventricle
- Considered normal if < 30 years old (may persist in women up to 50 years old)
- Heard in left ventricular failure, constrictive pericarditis
- Gallop rhythm (S3) is an early sign of LVF
What is S4? what is this caused by?
- may be heard in aortic stenosis, HOCM, hypertension
- caused by atrial contraction against a stiff ventricle
- in HOCM a double apical impulse may be felt as a result of a palpable S4
what is pulsus parodoxus?
-when is this seen?
Pulsus parodoxus
• Greater than the normal (10 mmHg) fall in systolic blood pressure during inspiration → faint or
absent pulse in inspiration
• Severe asthma, cardiac tamponade
when is a slow rising pulse seen?
Slow-rising/plateau
• Aortic stenosis
when is a collapsing pulse seen?
Collapsing
• Aortic regurgitation
• Patent ductus arteriosus
• Hyperkinetic (anemia, thyrotoxic, fever, exercise/pregnancy)
what is pulsus alterans? when is this seen?
Pulsus alternans
• Regular alternation of the force of the arterial pulse
• Severe LVF
what is a bisferiens pulse? when is this seen?
Bisferiens pulse
• ‘Double pulse’ - two systolic peaks
• Mixed aortic valve disease
*HOCM may occasionally be associated with a bisferiens pulse
when is a jerky pulse felt?
‘Jerky’ pulse
• Hypertrophic obstructive cardiomyopathy
What does the ‘a’ wave in JVP represent?
- when is this large?
- what are cannon ‘a’ waves? when is this seen?
‘a’ wave = atrial contraction
• Large if high atrial pressure e.g. Tricuspid stenosis, pulmonary stenosis, pulmonary
hypertension
• Absent if in atrial fibrillation
Cannon ‘a’ waves
• Caused by atrial contractions against a closed tricuspid valve
• Are seen in complete heart block, ventricular tachycardia/ectopics, nodal rhythm,
single chamber ventricular pacing
what causes the ‘c’ wave in jvp?
-is this normally visible?
- Closure of tricuspid valve
* Not normally visible
when are giant ‘v’ waves seen in JVP?
• Giant v waves in tricuspid regurgitation
what is the ‘x’ descent in JVP?
Fall in atrial pressure during ventricular systole
what is the ‘y’ descent in JVP?
Opening of tricuspid valve