ECG Flashcards
Term for change in membrane potential during the action potential.
Depolarization
In contractile cardiac muscle cells, plateau phase of action potential is due to
Ca2+ influx
A normal ECG doesn’t exclude:
MI (Check ST)
Intermittent Rhythm Disturbance (Do ambulatory 24h or 7d monitor)
Stable Angina (Ischaemic Heart Disease - do Exercise ECG)
ST segment denotes:
Ventricular systole (ST segment is isoelectric)
________ stimulation dominates under resting condition.
Parasympathetic
MABP is determined by:
CO et SVR
What heart sound is usually pathological?
4th heart sound
What can cause postural hypotension?
Fall in cardiac output
Pacemaker potential is due to:
Decreased K+ Efflux
Funny current (Na+ et K+ influx)
Transient Ca2+ influx
Rising phase of action pot (depolarization) caused by _________ and results in _______.
Activation of long-lasting L-type Ca2+ channels, Ca2+ influx
Falling phase of action pot (repolarization) caused by ____ et ____ and results in _______.
Inactivation of L-type Ca2+ channels, activation of K+channels, K+ efflux
Why does heart rate increase during inspiration?
Heart rate is normally controlled by centers in the medulla oblongata. One of these centers, the nucleus ambiguus, increases parasympathetic nervous system input to the heart via the vagus nerve. The vagus nerve decreases heart rate by decreasing the rate of SA node firing. Upon expiration the cells in the nucleus ambiguus are activated and heart rate is slowed down. In contrast, inspiration triggers inhibitory signals to the nucleus ambiguus and consequently the vagus nerve remains unstimulated.
Bifid P wave
Atrial enlargement
Long QT could be indicative of
TdP
Short PR segment
WPW, pre - Excitation
