The key difference between Chronotropic and Dromotropic is that chronotropic drugs affect the heart rate while dromotropic drugs affect the conduction velocity or the speed of the electrical impulse through the conducting tissues. Furthermore, chronotropic drugs affect the electrical conduction system of the heart and the nerves while the dromotropic drugs affect the atrioventricular node (AV node) conduction.
Diseases related to the heart and blood vessels are known as cardiovascular diseases. Heart attack, heart failure, arrhythmias, cardiomyopathy, angina, and stroke are some of them. Doctors prescribe cardiac drugs in order to prevent above diseases and keep your heart healthy. There are three main types of cardiac drugs in cardiac medication. Chronotropic and Dromotropic are two types among them.
CONTENTS
1. Overview and Key Difference
2. What is Chronotropic
3. What is Dromotropic
4. Similarities Between Chronotropic and Dromotropic
5. Side by Side Comparison – Chronotropic vs Dromotropic in Tabular Form
6. Summary
What is Chronotropic?
Chronotropic is a type of cardiac drugs that can change the heart rate. This is done by altering the ion channels such as sodium channels, potassium channels, and calcium channels to allow more or fewer ions flow in cardiac pacemaker cells. There are two types of chronotropic drugs namely positive chronotropic drugs and negative chronotropic drugs. Heart rate increases by the chronotropic drugs. On the other hand, heart rate decreases by the negative chronotropic drugs.
Figure 01: Heart Rate
Most adrenergic agonists, atropine, dopamine, epinephrine, isoproterenol, milrinone are several positive chronotropic drugs. Metoprolol, acetylcholine, digoxin, diltiazem and verapamil are negative chronotropic drugs.
What is Dromotropic?
Dromotropic is a drug type of cardiac drugs that alter the conduction velocity. In other words, these drugs change the traveling speed of impulses from SA node to AV node. AV node is a highly specialized conducting tissue.
Figure 02: SA Node and AV Node
Two types of dromotropic drugs are found namely positive dromotropic drugs and negative dromotropic drugs. The first type increases the conduction velocity while latter decreases the conduction velocity.
What are the Similarities Between Chronotropic and Dromotropic?
- Both Chronotropic and Dromotropic are two types of cardiac drugs use to treat cardiac diseases.
- Overdose of both drugs can lead to various disease conditions.
- Both drugs are in two types; positive and negative.
What is the Difference Between Chronotropic and Dromotropic?
Chronotropic drugs are the cardiac drugs that affect the heart rate. Dromotropic drugs are the cardiac drugs that affect the conduction velocity. Therefore, Chronotropic drugs change the heart rate and rhythm while Dromotropic drugs change the speed of impulses transferring from SA node to AV node.
Furthermore, chronotropic drugs affect the electrical conduction system of the heart and the nerves while the dromotropic drugs affect the atrioventricular node (AV node) conduction. There are positive and negative drugs forms in both these drugs. Positive chronotropes increase heart rate while negative chronotropes decrease heart rate. However, the positive dromotrope increases AV nodal conduction while negative dromotrope decreases AV nodal conduction.
Summary – Chronotropic vs Dromotropic
There are three types of cardiac drugs based on their use for cardiovascular disease treatments. They are inotropic, chronotropic and dromotropic drugs. Chronotropic drugs affect the heart rate by altering the ion channels to increase or decrease the ion flow to pacemaker cells. Dromotropic drugs change the conduction velocity or the speed of traveling the impulses from SA node to AV node. This is the difference between chronotropic and dromotropic drugs.
Reference:
1.“Chronotropic.” Wikipedia, Wikimedia Foundation, 22 Apr. 2018. Available here
2.“Inotropic, Chronotropic, Dromotropic Effects of the Heart.” YouTube, YouTube, 27 Feb. 2017. Available here
Image Courtesy:
1.’1375324′ by ellisedelacruz (CC0) via pixabay
2.’WPW’By Tom Lück – Own work, (CC BY 3.0) via Commons Wikimedia
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