What is orthodromic conduction of the action potential?
In an orthodromic study, the recording electrodes measure the action potential traveling in the physiologic direction. In an antidromic study, the recording electrodes measure the action potential traveling opposite the physiologic direction.
What is antidromic and orthodromic conduction?
An antidromic impulse in an axon refers to conduction opposite of the normal (orthodromic) direction. That is, it refers to conduction along the axon away from the axon terminal(s) and towards the soma.
How are action potentials elicited?
If the suprathreshold current stimulus is long enough, however, a train of action potentials will be elicited. In general, the action potentials will continue to fire as long as the stimulus continues, with the frequency of firing being proportional to the magnitude of the stimulus (Figure 1.4).
How can action potential be elicited and propagated?
Functional electrical stimulators From the spinal cord, an action potential propagates along a nerve fiber until it enters the belly of a muscle. There, it propagates through branches of the nerve fiber, which stimulate from three to several hundred skeletal muscle fibers.
What is orthodromic nerve conduction?
These orthodromic studies measure the compound motor action potential in the physiologic direction, such that the stimulation site is proximal and the recording electrode is placed distally over the muscle belly. The chapter discusses motor nerve conduction studies and sensory nerve conduction studies.
How is an antidromic action potential possible?
Electrical stimulation of the central nervous system creates both orthodromically propagating action potentials, by stimulation of local cells and passing axons, and antidromically propagating action potentials, by stimulation of presynaptic axons and terminals.
How action potential is generated in a neuron?
Action potentials are caused when different ions cross the neuron membrane. A stimulus first causes sodium channels to open. Because there are many more sodium ions on the outside, and the inside of the neuron is negative relative to the outside, sodium ions rush into the neuron.
Which part’s of the neuron can conduct an action potential?
Axon – The long, thin structure in which action potentials are generated; the transmitting part of the neuron.
What is orthodromic AVRT?
In orthodromic AVRT, anterograde conduction occurs via the AV node, resulting in a normal direction of ventricular depolarisation. This can occur in patients with a concealed pathway (AP that conducts retrograde only, not evident on sinus rhythm ECG).
What is the definition antidromic?
Definition of antidromic : proceeding or conducting in a direction opposite to the usual one —used especially of a nerve impulse or fiber.
What causes hyperpolarization in action potential?
Depolarization and hyperpolarization occur when ion channels in the membrane open or close, altering the ability of particular types of ions to enter or exit the cell. For example: The opening of channels that let positive ions flow out of the cell (or negative ions flow in) can cause hyperpolarization.
How can you tell the difference between AVNRT and orthodromic AVRT?
Orthodromic AVRT, or just AVNRT? This rhythm can appear very similar to AVNRT, but the RP interval can assist us to differentiate: In typical AVNRT, retrograde P waves occur early, so we either don’t see them (buried in QRS) or partially see them (pseudo R’ wave at terminal portion of QRS complex)
What causes orthodromic AVRT?
Orthodromic AVRT represent approximately 95% of all cases of AVRT and it arises when a premature atrial beat encounters a refractory accessory pathway but excitable atrioventricular node.