It is essential that the cardiac action potential duration (APD) is regulated precisely. The APD determines the refractory period of the heart and if it becomes too short premature re-excitation can occur, leading to such arrhythmogenic phenomena as re-entry.
What is ERP and APD?
ERP/APD ratio in patients with prior atrial fibrillation or flutter. … Afib = Atrial fibrillation; Aflut = atrial flutter; APD70= Action potential duration at 70% repolarization; APD90= action potential duration at 90% repolarization; BCL = basic cycle length; ERP = effective refractory period; Repol.
What is an action potential duration?
In a typical nerve, the action potential duration is about 1 ms. In skeletal muscle cells, the action potential duration is approximately 2-5 ms. In contrast, the duration of cardiac action potentials ranges from 200 to 400 ms.
What happens if action potential duration increases?
By increasing the action potential duration and excitability in peripheral nerves, Kv1 voltage-gated potassium channel blockers may improve conduction of electrical impulses through nerves with damaged or destroyed protective myelin sheath.
What is early Afterdepolarization?
Abstract. Early afterdepolarizations (EADs) are secondary voltage depolarizations during the repolarizing phase of the action potential, which can cause lethal cardiac arrhythmias.
What does PSVT stand for in medical terms?
Paroxysmal supraventricular tachycardia (PSVT) is a type of abnormal heart rhythm, or arrhythmia. It occurs when a short circuit rhythm develops in the upper chamber of the heart.
Which drug is an antiarrhythmic?
Antiarrhythmic drugs
- amiodarone (Cordarone, Pacerone)
- flecainide (Tambocor)
- ibutilide (Corvert), which can only be given through IV.
- lidocaine (Xylocaine), which can only be given through IV.
- procainamide (Procan, Procanbid)
- propafenone (Rythmol)
- quinidine (many brand names)
- tocainide (Tonocarid)
What are the two types of refractory periods?
There are two types of refractory periods; the absolute refractory period, which corresponds to depolarization and repolarization, and the relative refractory period, which corresponds to hyperpolarization.
What is ERP in electrophysiology?
An event-related potential (ERP) is the measured brain response that is the direct result of a specific sensory, cognitive, or motor event. More formally, it is any stereotyped electrophysiological response to a stimulus. … ERPs are measured by means of electroencephalography (EEG).
What are the 4 steps of an action potential?
An action potential is caused by either threshold or suprathreshold stimuli upon a neuron. It consists of four phases: depolarization, overshoot, and repolarization.
What triggers an action potential?
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.
What are the 5 steps of an action potential?
The action potential can be divided into five phases: the resting potential, threshold, the rising phase, the falling phase, and the recovery phase.
How does a neuron return to resting potential?
Repolarization – brings the cell back to resting potential. The inactivation gates of the sodium channels close, stopping the inward rush of positive ions. At the same time, the potassium channels open. … This means the cell loses positively charged ions, and returns back toward its resting state.
Are biogenic amine neurotransmitters such as dopamine?
Are biogenic amine neurotransmitters such as dopamine considered to be proteins? No, it simply means that dopamine has at least one amine functional group in its molecular structure.
How long does a cardiac action potential last?
about 300 ms. The cardiac action potential lasts about 300 ms. For the vast majority of this time, the cell is absolutely refractory to further stimulation. In other words, a further action potential will not be generated until repolarization is virtually complete.
What causes delayed Afterdepolarization?
Delayed afterdepolarizations They are due to elevated cytosolic calcium concentrations, classically seen with digoxin toxicity. The overload of the sarcoplasmic reticulum may cause spontaneous Ca2 + release after repolarization, causing the released Ca2 + to exit the cell through the 3Na+/Ca2 +-exchanger.
When do early Afterdepolarizations occur?
Early after-depolarizations occur during phase 2 or 3 of the action potential and are believed to be the initiating mechanism of torsades de pointes ventricular tachycardia. Late after-depolarizations occur in phase 4 of the action potential and are responsible for some digitalis-intoxication tachyarrhythmias.
What are early and delayed Afterdepolarization?
Early afterdepolarizations occur during late phase 2 or phase 3 and can lead to a salvo of several rapid action potentials or a prolonged series of action potentials. … Delayed afterdepolarizations occur in late phase 3 or early phase 4 when the action potential is nearly or fully repolarized.
Is PSVT life threatening?
Background: PSVT (Paroxysmal Supraventricular Tachycardia) is a common heart disease, especially in young people. Although PSVT is not a life-threatening illness, its symptoms occur in a sudden onset and with increasing frequency.
Can PSVT cause stroke?
Risk of ischemic stroke among patients with paroxysmal supraventricular tachycardia. The pooled analysis found a significantly increased risk of ischemic stroke among patients with PSVT compared to individuals with PSVT without the pooled RR of 2.03 (95% CI, 1.223.38).
Can anxiety cause PSVT?
Reciprocally, palpitations caused by paroxysmal supraventricular tachycardia (PSVT) are commonly associated with anxiety and may therefore be misdiagnosed as PD.
Is amlodipine an antiarrhythmic?
Dihydropyridines, like amlodipine, nicardipine, and nifedipine, are highly selective for calcium channels on the vascular smooth muscle tissue; so they’re primarily used to treat hypertension. On the other hand, non-dihydropyridines are the class IV antiarrhythmics and they include verapamil and diltiazem.
What is the main cause of arrhythmia?
The most common type of arrhythmia is atrial fibrillation, which causes an irregular and fast heart beat. Many factors can affect your heart’s rhythm, such as having had a heart attack, smoking, congenital heart defects, and stress. Some substances or medicines may also cause arrhythmias.
What are the 4 classes of antiarrhythmic drugs?
Antiarrhythmic drug classes:
- Class I – Sodium-channel blockers.
- Class II – Beta-blockers.
- Class III – Potassium-channel blockers.
- Class IV – Calcium-channel blockers.
- Miscellaneous – adenosine. – electrolyte supplement (magnesium and potassium salts) – digitalis compounds (cardiac glycosides)
What causes hyperpolarization?
Hyperpolarization is often caused by efflux of K+ (a cation) through K+ channels, or influx of Cl (an anion) through Cl channels. … While hyperpolarized, the neuron is in a refractory period that lasts roughly 2 milliseconds, during which the neuron is unable to generate subsequent action potentials.
Why is the refractory period important?
The refractory period limits the rate at which action potentials can be generated, which is an important aspect of neuronal signaling. Additionally, the refractory period facilitates unidirectional propagation of the action potential along the axon.
What does the refractory period prevent?
It is initiated by paced or sensed events; after a sensed event, the refractory period prevents double counting the same event, whereas after a paced event, it prevents sensing the pacing stimulus, its after-potential, or the evoked response. Events within the refractory period do not reset the LRI.
What are AV nodes?
The atrioventricular (AV) node is a small structure in the heart, located in the Koch triangle,[1] near the coronary sinus on the interatrial septum. In a right-dominant heart, the atrioventricular node is supplied by the right coronary artery.
Is ERP expensive?
A 2020 ERP report showed that the average budget per user for an ERP project is $8,265. When you factor in how many users your system may have (especially for larger businesses), and added costs, you’ll find an ERP implementation can cost anything between $150,000 and $750,000 for a mid-sized business.
What are examples of ERP?
ERP Software Examples
- SAP S/4HANA. This next-generation service is known for its far-reaching compatibility with multiple company sizes and existing software.
- Oracle Cloud ERP. Oracle is one of the most well-established software companies in the world. …
- Sage Intacct. …
- Epicor ERP.
