What generates cardiac rhythm?
Written by Shanaiah Regine M. Tonelete
Cardiac rhythm is the heart’s rhythm or the electrical activity of the heart. People assume that this only pertains to the heart’s contraction and relaxation. Yet, every heartbeat you have is far more complex than that.
If you can recall, the heart has four chambers. The upper chambers are the atria (sing. atrium), while the lower ones are the ventricles. These chambers, together with specific bundles of cells, generate your cardiac rhythm.
Whenever your heart beats, a bundle of specialized cells works to regulate it. The sinoatrial (SA) node (sinus node) sends electrical impulses to begin your heartbeat. The SA node is your heart’s natural pacemaker; thus, it sets your heart’s rate and rhythm.
The sinus node, found at the right atrium’s epicardium, sends impulses to your atria. These impulses spread to the walls of each atrium which prompts their contraction. When the atria contract, it allows blood to flow towards your ventricles.
Before reaching the ventricles, the blood needs to pass a specific cluster of cells. The atrioventricular (AV) node acts as a gateway for your blood. It slows down the signal sent by the SA node to allow your atria to contract before the ventricles.
Meanwhile, the His-Purkinje Network spreads the impulse to the lower chambers’ walls. It causes your ventricles to contract and pump blood to the lungs and body.
These nodes and fibers allow your heart to have a controlled beating. When the ventricles release blood, the SA node sends another electrical impulse. It will trigger another heartbeat, and the cycle continues.
What is an abnormal cardiac rhythm called?
When your heart rhythm is too slow or fast, it can suggest many things. This abnormality in your cardiac rhythm refers to arrhythmia (dysrhythmia). Arrhythmia originated from the Greek words a– and rhythmos which means loss of rhythm.
To know whether you have an irregular heartbeat, you need to measure your pulse. The regular heart rate ranges from 50 to 100 beats per minute (bpm). You can count it by touching your wrist and neck or using an electrocardiogram (EKG).
The usual classifications for abnormal cardiac rhythms are bradycardia and tachycardia. A rate lower than 60 bpm is bradycardia. A rate greater than 100 bpm is tachycardia.
Another way to know if you have arrhythmia is when you experience palpitations. You can also suffer from shortness of breath and fatigue. Although these symptoms are subjective and some people may not have them.
There are also various reasons why you can have this condition. It can be due to hypertension, valve disorders, and other medical conditions. Your excessive consumption of alcohol/coffee and exercising can also cause it.
Cardiologists often use some tests to diagnose arrhythmia. The tests to confirm the presence of abnormal heartbeats include:
- Cardiac Catheterization
- Electrophysiology Study (EPS)
- Stress Test
- Tilt Table Test
What are the 5 lethal cardiac rhythms?
The word lethal is often associated with death. It means that something is destructive or harmful for you. Thus, lethal cardiac rhythms can infer that these rhythms might cause your death. Here are five arrhythmias considered lethal.
Premature Ventricular Contraction (PVC)
PVC is an ectopic (abnormal) beat in your ventricles but is not an actual rhythm. It causes the ventricles to depolarize before the next sinus beat. Thus, it earned the label of premature.
Since PVCs arise in ventricles, there are changes in the ventricular depolarization sequence. The extra beats due to PVCs disrupt your heart’s rhythm. Although PVCs are often benign, some are life- threatening due to other heart problems.
Ventricular Tachycardia (VT)
Three or more consecutive PVCs or heartbeats can suggest ventricular tachycardia. VT is an abnormal heart rate that starts in the lower chambers of your heart. Its usual rate is 100-250 bpm.
Some of the possible causes of VT include cardiomyopathy and coronary artery disease. VT can be life-threatening if it continues for more than a few seconds.
Ventricular Fibrillation (VF)
When there is disorganization in the ventricles’ electrical activity, they will quiver. This condition is what you call ventricular fibrillation. Scientists describe the ventricular myocardium as a “can of worms” during VF.
VF is dangerous since there is no cardiac output when your ventricles quiver. Thus, there is no palpable pulse, no blood pressure, and you will become cyanotic. Within 3-5 minutes, this rhythm can become lethal.
Some of the possible causes of VF are cardiomyopathy and untreated ventricular tachycardia. Acid- base imbalance and electrolyte imbalances can also result in VF.
Asystole is the absence of movement or electrical activity in your heart. You can see it as a flat line on the EKG screen. When you have asystole, it means that you have no heart rate and rhythm.
Although VF and asystole seem similar, you can differentiate them through telemetry reading. Asystole becomes lethal when it persists for more than fifteen minutes. It can cause death since there is not enough oxygen to supply your body, especially the brain.
Pulseless Electrical Activity (PEA)
When your heart has an electrical activity but no pulse, you have a condition called PEA. Since you have no cardiac output, you will be pulseless and unconscious. Often, hypovolemia causes PEA.
Various rhythms belong to this category. It includes electromechanical dissociation (EMD), bradyasystole rhythm, and pseudo-EMD.
It is a condition characterized by having an irregular rhythm with a rate of ≤20 bpm. It is the rhythm seen during the last stages of unsuccessful resuscitation. The agonal rhythm later ends at asystole.
How long can you live with irregular heart beat?
Having arrhythmia is a challenge. Being able to live a comfortable life despite having it depends on the type of arrhythmia you have. Your life expectancy also depends on it.
If you have a harmless or benign arrhythmia, you can live a healthy and longer life. There is no definite life span for those with benign arrhythmias. Research only reveals that people with harmless arrhythmias do not need treatment. But treatment is not necessary only if there are no other complications involved.
Meanwhile, those considered life-threatening can give you a few minutes if not treated. Lethal arrhythmias such as ventricular fibrillation and asystole can grant you 3-15 minutes. If not immediately treated within that time, it can cause your death.
What is the best medication for irregular heartbeat?
Antiarrhythmic drugs are the medications used by people with irregular heartbeats. These drugs treat the abnormality in your heart rhythm or slow its rate.
It is necessary to consult your doctor first before taking any medications. You can choose between two approaches to taking the drugs. These are the “pill in the pocket” method and regular intake.
The “pill in the pocket” method is helpful when your episodes appear less frequent. You can put the pill in your wallet and take it when you experience an arrhythmia episode. Meanwhile, the second method is taking the drugs every day.
Some medications prescribed by doctors are beta-blockers and calcium channel blockers.
These drugs decrease your cardiac output. They help slow down your heart’s rhythm, but they may also stop your arrhythmia. They work by blocking the effects of adrenaline which lowers your blood pressure.
Some of the examples of beta-blockers are sotalol and nadolol. Bisoprolol and metoprolol (beta- blockers) can also treat atrial fibrillation (AF).
Calcium Channel Blockers
These refer to the drugs that interrupt calcium movement in the heart. Thus, they are calcium antagonists. If there is less calcium, then there is a reduction in the heart’s electrical activity.
Verapamil and diltiazem are examples of calcium antagonists. Those who have AF can also take digoxin.
Can irregular heartbeat go back to normal?
Irregular heartbeat is often reversible. It goes back to normal on its own, but there are also things you can do to regulate your heart rate.
When you exercise, it is normal to have an increased rate after. Overexercising can result in the irregular beating of your heart muscle. Too much caffeine, alcohol, or nicotine can also trigger it.
To avoid this, you can do the following:
- Avoid too much consumption of caffeine
- Avoid alcohol
- Avoid stimulant drugs
- Do not smoke
- Get enough sleep
- Relax and manage your stress
Meanwhile, some arrhythmias are possible to regulate but hard to restore. Taking medications can repair them for a while, but without them, they will return. These are the arrhythmias associated with other heart problems. Scientists claim that irregular heartbeats are incurable. Unless treatment for other complications is available, then they will remain.
Some of the causes of this type of arrhythmia are high blood pressure and damaged heart tissue and. Congenital heart problems and inflammatory disorders can also cause it.
Can stress cause an irregular heart beat?
The heart and brain have a complex interaction with each other. When you experience physical or emotional stress, your brain sends a signal to the rest of your body. The heart receives this signal, then increases its heartbeat and elevates blood pressure.
Thus, stress-induced cardiac arrhythmias are possible. Negative emotions prompt the release of catecholamines or stress hormones. These hormones are responsible for your fight-or-flight response.
The heart’s cardiac output increases when the adrenal glands release catecholamines. This hormone increases the contractility and excitability of the cardiac muscle. It also increases the AV nodal conduction velocity and the SA nodal discharge rate of the heart. Thus, increasing the cardiac output.
To avoid having stress-induced arrhythmias, you can try doing:
- Eating nutritious food
- Have a positive attitude
- Regular exercise
If irregular heartbeats continue to persist, you can try contacting your doctor. There might be other reasons why you have the condition. It is necessary to seek professional advice before taking any medications.
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