How does action potential relate to ECG?

The phases of the cardiac action potential correspond to the surface ECG (ECG) (Figure). The P wave reflects atrial depolarization (phase 0), the PR interval reflects the conduction velocity through the AV node, the QRS complex the ventricular depolarization and QT interval the duration potential ventricular action.

How does TTX affect the heart?

Tetrodotoxin given to cats in doses of 1 to 10 fi,g/kg iv caused profound cardiovascular depression characterized by decreases in systolic and diastolic blood pressures, pulse pressure, heart rate, force of myocardial contraction, cardiac output and peripheral resistance.

What are the differences between action potential and ECG action potential?

The action potential includes a depolarization (activation) followed by a repolarization (recovery). As mentioned earlier, the electrical potentials of the conduction system are much too minute to be detected by skin electrodes; the ECG presents electrical activity of atrial and ventricular myocardium.

Where on an ECG would the action potential of a ventricular cardiomyocyte be?

The QRS complex of the electrocardiogram corresponds to the action potential depolarization, while the T wave is associated with ventricular repolarization.

What are ECG artifacts?

Electrocardiographic artifacts are defined as electrocardiographic alterations, not related to cardiac electrical activity. As a result of artifacts, the components of the electrocardiogram (ECG) such as the baseline and waves can be distorted. Motion artifacts are due to shaking with rhythmic movement.

What are the phases of ECG?

A typical ECG tracing of the cardiac cycle (heartbeat) consists of a P wave (atrial depolarization ), a QRS complex (ventricular depolarization), and a T wave (ventricular repolarization). An additional wave, the U wave ( Purkinje repolarization), is often visible, but not always.

How does TTX affect action potential?

Tetrodotoxin (TTX) is a potent toxin that specifically binds to voltage gated sodium channels. TTX binding physically blocks the flow of sodium ions through the channel, thereby preventing action potential (AP) generation and propagation.

What is TTX neurotoxin?

Tetrodotoxin (TTX) is a potent neurotoxin. Its name derives from Tetraodontiformes, an order that includes pufferfish, porcupinefish, ocean sunfish, and triggerfish; several of these species carry the toxin.

What is the action potential of an ECG?

As the impulse spreads through the myocardium, it activates the cells which respond by contracting. The action potential generates electrical currents that give rise to the classical ECG waveforms presented here.

Does TTX have an effect on slow action potentials?

TTX has little effect on slow action potentials due to the activation of the slow channel. Action potential duration and force were affected similarly by TTX as a function of concentration, of time of exposure and of rate of discharge.

What is the action potential of the heart?

The action potential includes a depolarization (activation) followed by a repolarization (recovery). The action potential occurs in all cardiac cells but its appearance varies depending on cell type.

What does the T wave mean on an ECG?

The T-wave reflects the recovery (repolarization) of the ventricles. Note that the ECG rarely shows atrial recovery (repolarization) since it coincides with ventricular depolarization (i.e QRS complex), which has much stronger electrical potentials. Cell types in electrocardiology