Action of Drugs on Cardiovascular System

Venodilation, specifically widening of blood vessels in the venous system, directly reduces the amount of blood returning to the heart. This reduction in preload decreases the workload on the heart, resulting in a lower force of contraction and, subsequently, lower oxygen demand.

Organic nitrates, a type of medication, improve oxygen delivery to the heart muscle by dilating collateral arteries. Collateral arteries are smaller, alternative pathways for blood flow, which get enlarged by nitrates, increasing blood flow to the heart muscle, particularly areas that are starved of oxygen.

Atrial fibrillation, acute myocardial infarction, and mechanical prosthetic heart valves are among the cardiac conditions that significantly increase the risk of blood clots forming.

A drug that increases the force of heart muscle contraction, leading to a stronger heartbeat.

A drug that reduces the force of heart muscle contraction, leading to a weaker heartbeat.

A condition where the heart cannot pump blood effectively to meet the body's needs.

A drug that increases the force of heart muscle contraction by blocking the sodium-potassium pump (Na+/K+ ATPase) in heart muscle cells.

An example of cardiac glycosides.

A drug that increases heart rate by stimulating beta-adrenergic receptors.

The ability of a drug to increase the force of heart muscle contraction.

The measure of how well the heart pumps blood.

The amount of pressure the heart must overcome to pump blood out of the heart.

The amount of pressure inside the heart chambers before contraction.

Arrhythmias or dysrhythmias are abnormalities of the heart rate or rhythm. Examples include tachycardia, bradycardia, atrial flutter, atrial fibrillation, and ventricular fibrillation.

Ectopic pacemaker activity is when a damaged area of the myocardium becomes spontaneously active and takes over the heart's rhythm, leading to arrhythmias.

After-depolarizations are abnormal electrical impulses that occur after the normal heart beat. They are caused by high levels of calcium within heart cells and contribute to arrhythmias.

A re-entry loop is a circular path of electrical impulses that delays or blocks the normal spread of excitation in the heart. This can lead to sustained arrhythmias.

Ventricular tachycardia is a rapid heartbeat originating in the ventricles (the heart's lower chambers). It's a serious arrhythmia that can lead to heart failure.

Supraventricular tachycardia (SVT) is a fast heart rate originating in the upper chambers of the heart (atria). It's a common arrhythmia that can cause palpitations.

Bradycardia is a slow heart rate, typically below 60 beats per minute. It can be caused by various factors such as medications, heart conditions, and lifestyle habits.

Atrial fibrillation is a fast and irregular heart rhythm occurring in the atria. It's the most common type of arrhythmia, leading to fatigue, palpitations, and an increased risk of stroke.

These drugs block the sympathetic nervous system, which is responsible for increasing heart rate and contractility. They are often used following a myocardial infarction to prevent arrhythmias and reduce oxygen demand.

Drugs that affect the force of contraction of the heart.

Drugs that block voltage-gated sodium channels in the open or inactive state, which prevents the generation of action potentials.

Drugs that block potassium channels, prolonging the action potential and the absolute refractory period, which prevents a new action potential from occurring too soon.

Drugs that block calcium channels, reducing the slope of the pacemaker action potential at the SA node, decreasing AV nodal conduction, and decreasing the force of contraction.

A type of Class III antiarrhythmic that not only blocks potassium channels but also has other actions, used to treat tachycardia associated with Wolff-Parkinson-White syndrome.

A drug that enhances potassium conductance, leading to hyperpolarization of the conducting tissue and antiarrhythmic effects, administered intravenously.

These drugs target the sodium channels in the open or inactive state, preventing the rapid depolarization of heart cells, and are sometimes used for treating ventricular tachycardia after a myocardial infarction.

Drugs that block potassium channels, prolonging the action potential and the absolute refractory period, which prevents a new action potential from occurring too soon, but are not generally used due to potential proarrhythmic effects.

Damaged areas of the myocardium can become depolarized and fire automatically, leading to arrhythmias. Lidocaine blocks these open sodium channels in the depolarized tissue, preventing automatic firing.

Dobutamine is a medication that primarily targets beta-1 receptors in the heart. It helps to increase heart muscle contractility, ultimately leading to improved blood flow and the ability of the heart to pump blood effectively.

ACE inhibitors are a class of drugs that prevent the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor and a substance promoting fluid retention. By blocking this conversion, ACE inhibitors help reduce blood pressure, afterload on the heart, and fluid retention.

Diuretics are medications that increase the excretion of water and sodium from the body. By reducing the amount of fluid in the bloodstream (pre-load), diuretics help reduce the workload on the heart.

Beta-blockers are medications that block the effects of adrenaline and noradrenaline on the heart, thus reducing heart rate and contractility. By lowering the workload on the heart, beta-blockers help alleviate symptoms of angina.

Organic nitrates are medications that are converted to nitric oxide (NO) in the body. NO acts as a powerful vasodilator, relaxing blood vessels and improving blood flow to the heart, alleviating symptoms of angina.

Angina, or myocardial ischemia, occurs when the oxygen supply to the heart muscle doesn't meet its demand. This usually happens due to narrowing of the coronary arteries, leading to chest pain, especially during exertion.

Calcium channel antagonists are medications that block the entry of calcium into heart muscle cells. This reduces the force of heart contractions and relaxes blood vessels, both of which reduce the workload on the heart.

Organic nitrates, such as glyceryl trinitrate (GTN) and isosorbide dinitrate, are medications that are converted to nitric oxide, a powerful vasodilator, which helps relax blood vessels and improve blood flow to the heart.