What are Chronotropy Inotropy and Lusitropy?

What are Chronotropy Inotropy and Lusitropy?

Stimulation of the Beta1-adrenergic receptors in the heart results in positive inotropic (increases contractility), chronotropic (increases heart rate), dromotropic (increases rate of conduction through AV node) and lusitropic (increases relaxation of myocardium during diastole) effects.

What does increased Lusitropy mean?

Lusitropy is the rate of myocardial relaxation. The increase in cytosolic calcium of cardiomyocytes via increased uptake leads to increased myocardial contractility (positive inotropic effect), but the myocardial relaxation, or lusitropy, decreases.

What causes Lusitropy?

One such case is the stimulation of cardiac β-adrenoceptors. In general, this leads to a general excitation of cardiac response composed of an increase in heart rate (for right atria), an increased force of contraction (inotropy), and an increase in the rate of muscle relaxation (lusitropy).

What are lusitropic drugs?

Several drugs have the potential to improve ventricular relaxation (lusitropic effect). The drugs that increase myocardial cyclic adenosine monophosphate concentrations, such as b-adrenergic agonists and cardiac-specific phosphodiesterase inhibitors, may also enhance myocardial relaxation.

What is dromotropic effect?

A dromotropic agent is one which affects the conduction speed (in fact the magnitude of delay) in the AV node, and subsequently the rate of electrical impulses in the heart. Positive dromotropy increases conduction velocity (e.g. epinephrine stimulation), negative dromotropy decreases velocity (e.g. vagal stimulation).

What do you mean by chronotropic and dromotropic effects of heart?

Positive chronotropes increase heart rate; negative chronotropes decrease heart rate. A dromotrope affects atrioventricular node (AV node) conduction. A positive dromotrope increases AV nodal conduction, and a negative dromotrope decreases AV nodal conduction. A lusitrope is an agent that affects diastolic relaxation.

What is preload and after load?

Preload is the initial stretching of the cardiac myocytes (muscle cells) prior to contraction. It is related to ventricular filling. Afterload is the force or load against which the heart has to contract to eject the blood.

Is digoxin a positive dromotropic?

Finally, digoxin has a negative dromotropic effect on the atrioventricular node, leading to an increase in refractory periods and nodal conduction time.

What drugs reduce afterload?

Substances

• Vasodilator Agents.
• Nitroprusside.
• Hydralazine.
• Nitroglycerin.
• Prazosin. Phentolamine.

What drugs increase afterload?

Norepinephrine increases blood pressure and afterload; it may decrease cardiac output and increase myocardial oxygen demand and cardiac ischemia. This agent is generally reserved for patients with severe hypotension (eg, systolic blood pressure < 70 mm Hg) or hypotension unresponsive to other medication.

Which drug reduces preload and afterload?

Milrinone. Milrinone is a positive inotropic agent and vasodilator. It reduces afterload and preload and increases cardiac output.

What causes high preload?

Preload is increased by the following: Increased central venous pressure (CVP), e.g., from decreased venous compliance due to sympathetic activation; increased blood volume; respiratory augmentation; increased skeletal pump activity. Increased ventricular compliance. Increased atrial contraction.

What does milrinone do to the heart?

MILRINONE (MILL rih none) is an inotrope and vasodilator. It increases the strength of the heart muscle and widens blood vessels. It is used to treat congestive heart failure.

What is dromotropic action?

The term dromotropic derives from the Greek word δρόμος drómos, meaning “running”, a course, a race. A dromotropic agent is one which affects the conduction speed (in fact the magnitude of delay) in the AV node, and subsequently the rate of electrical impulses in the heart.

What is lusitropy of myocardial relaxation?

Lusitropy is the rate of myocardial relaxation. The increase in cytosolic calcium of cardiomyocytes via increased uptake leads to increased myocardial contractility (positive inotropic effect), but the myocardial relaxation, or lusitropy, decreases.

What is the effect of lusitropy on cardiac contractility?

Lusitropy is the rate of myocardial relaxation. The increase in cytosolic calcium of cardiomyocytes via increased uptake leads to increased myocardial contractility (positive inotropic effect), but the myocardial relaxation, or lusitropy, decreases. This should not be confused, however, with catecholamine-induced calcium uptake…

What is the difference between lusitropy and inotropy?

In essence, lusitropy is diastolic function as inotropy (or contractility) is systolic function. Factors that produce positive lusitropy are: beta adrenergic agonists phosphorylate phospholamban via cAMP, reducing calcium available for binding with troponin.

What are dromotropic and inotropic drugs?

Dromotropic drugs affect conduction velocity through the conducting tissues of the heart. Inotropic, Chronotropic and Dromotropic are different types of cardiac drugs. This classification is based on the way these drugs are used for the treatment of a particular condition.