Cardiovascular Flashcards
What is normal heart rate?
60-100 bpm
What is the dominant pacemaker of the heart?
SA node
What is the intrinsic rate of the AV node?
40-60bpm
What is the impulse conduction pathway?
Sinoatrial node → AV node → Bundle of His → Bundle branches →
Purkinje fibres
How long is the average AV node delay?
0.12-0.2 S
How long is the average atrial depolarisation?
0.08-0.1 s
How long is the average ventricular depolarisation?
0.06-0.1S
On an ECG, which is the only lead to not show a P wave?
aVR
What does the P wave signify?
Atrial depolarisation
What does the PR interval signify?
Time taken for the atria to depolarise, and electrical activation to get through the AV node
What does the QRS complex signify?
Ventricular depolarisation
What does the ST segment signify?
The interval between depolarisation and repolarisation
What does the T wave signfiy?
Ventricular repolarisation
What is tachycardia?
Increased heart rate
What is bradycardia?
Decreased heart rate
What is dextrocardia?
The heart on the right side of the chest instead of the left
How many seconds is one small box on an ECG?
0.04s
How many mV is a large box on an ECG?
0.5mV
Where is the left ventricle palpated?
5th Intercostal space and mid-clavicular line
What is stroke vol?
The volume of blood ejected from each ventricle during systole
What is cardiac output?
The volume of blood each ventricle pumps as a function of time
How is cardiac output calculated?
Stroke volume (L) x Heart rate (BPM)
What is total peripheral resistance?
The total resistance to flow in systemic blood vessels from beginning of aorta to vena cava - arterioles provide the most resistance
What is preload?
The volume of blood in the left ventricle which stretches the cardiac myocytes before left ventricular contraction - how much blood is in the ventricles before it pumps
What is afterload?
the pressure the left ventricle must overcome to eject blood during contraction
What is contractility?
Force of contraction and the change in fibre length
What is elasticity?
Myocardial ability to recover normal shape after systolic stress
What is diastolic dispensibility?
The pressure required to fill the ventricle to the same diastolic volume
What is compliance?
How easily the heart chamber expands when filled with blood volume
What is Starlings law?
Force of contrition is proportional to the end diastolic length of cardiac muscle fibre - the more ventricle fills the harder it contracts
What is S1?
Mitral and tricuspid valve closure