The primary function of the heart is pump blood throughtout the body.
It supply oxygen
and nutrients to the tissues.
The heart pumps blood from the body to the lungs, where the blood is oxygenated. It then returns
the blood to the heart, which pumps the freshly oxygenated blood to the rest of the body.
Conduction is how electrical impulses travel through your heart, which causes it to beat.
Some conduction disorders can cause arrhythmias, or irregular heartbeats. The heart
conduction system is the network of nodes, cells and signals that controls your
heartbeat. Each time your heart beats, electrical signals travel through your heart. These
signals cause different parts of your heart to expand and contract.
cardiovascular drug (treatment of diseases of heart and blood vessels)
Any agent that affects the function of the heart and blood vessels. Drugs that act on
the cardiovascular system are among the most widely used in medicine.
Examples of disorders in which such drugs may be useful include
• hypertension (high blood pressure),
• angina pectoris (chest pain resulting from inadequate blood flow through
the coronary arteries to the heart muscle),
• heart failure (inadequate output of the heart muscle in relation to the
needs of the rest of the body), and
• arrhythmics (disturbances of cardiac rhythm).
myocardium
The myocardium is the muscular wall of the heart, or the heart muscle. It contracts to pump
blood out of the heart and then relaxes as the heart refills with returning blood. Cardiac muscle
tissue, or myocardium, is a specialized type of muscle tissue that forms the heart. This muscle tissue,
which contracts and releases involuntarily, is responsible for keeping the heart pumping blood
around the body.
What is depolarization and repolarization in heart?
Depolarization with corresponding contraction of myocardial muscle moves as a
wave through the heart. 7. Repolarization is the return of the ions to their previous
resting state, which corresponds with relaxation of the myocardial muscle.
Role of calcium, sodium and potassium: The two most important
electrolytes are potassium and calcium for heart function. They are both
vitally concerned with proper function of the cardiac muscle. Both
electrolytes are needed in the proper amounts for contraction of the
muscle.
Calcium particles enter the heart muscle cells during each heartbeat and
contribute to the electrical signal that coordinates the heart's function.
calcium regulates the opening and closing of sodium and potassium doors ,
to make the heart cell squeeze together (“contract”), which produces the
pumping function of the heart.
Potassium is the major cation inside living cells. We need potassium to keep the
electrochemical balance across cell membranes. This leads to heart contraction.
Even though sodium is an essential mineral, too much of it can increase your blood pressure.
Sodium pulls water into your bloodstream, but if there is too much sodium, it pulls in too much water.
The increase in water increases the volume of blood in your blood vessels — more blood equals more
pressure.
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Different types of drugs are
Cardiac glycosides
Antihypertensive drugs
Antiarrhythmic drugs
Antianginal drugs
Vasodilators
Lipid lowering agents etc.
Class 1:
Quinidine: It depresses myocardium. It is a dextorotatory isomer of drug quinine and is a
cinchona alkaloid. It is generally used as bisulphate form and is soluble in water. Orally it can
be given.
It depresses the entry of sodium into the cell during depolarization and depresses
automaticity which in turn suppress arrhythmic nature.
It reduces the excitability of the cardiac tissue.
Procainamide: It’s cardiac actions are similar to quinidine. This induces a moderte fall in blood
pressure and prevents rhythm disturbance under cyclopropane anaesthesia .
Class 2: Beta adrenergic blockers:
It reduces cardiac activity by decreasing beta adrenergic receptor stimulation. Beta blockers
cause the heart to beat more slowly and with less force, which lowers blood pressure. Beta
blockers also help widen veins and arteries to improve blood flow. It also reduce bp. Action
simililar to quinindine.
Propanolol hydrochloride
Class IV: Antagonists of calcium
Calcium blockers prevent calcium induced arrhythmias. These drugs selectively block the ca
influx into the excited heart muscles. They produced an effect on the force of cardiac
contractions and thus reduces conduction velocity.
Verapamil
Antianginal agents:
Antianginal agents is a term used to describe a wide variety of medicines that are used in the
management of angina. Angina is a heart condition characterized by a narrowing of the
coronary arteries (the arteries of the heart) (when the heart does not get proper nutrition
and oxygen) which leads to reduced blood flow to heart. Chest pain is its main
symptom. Angina results from an imbalance in the oxygen supply/demand ratio
Examples of antianginal agents include:
Nitrates (eg, isosorbide dinitrate, amyl nitrite, nitroglycerin). These relax smooth muscle
within the blood vessels, widening them and making it easier for blood and oxygen to reach
the heart.Both organic and inorganic nitrites dilate the coronaries.
Nitroglycerin: most used drug
It is a nitrate of glycerol. Sparingly soluble in water. Gives immediate relief from attack.
Reduces myocardial oxygen demands, relaxes muscle and have direct vasodilating action of
coronary blood vessels and thereby quickly reliving anginal pain. Tablet beneath the tongue.
Amyl nitrite
: It is administered by inhalation, rapidly absorbed from lungs.It is used for the treatment of
cyanide poisoning.
Isosorbide dinitrate: prevent heart failure.
Calcium antagonists (eg, diltiazem, nifedipine, nimodipine, verapamil). These inhibit calcium
transfer into cells thereby inhibiting contraction of vascular smooth muscle
Beta blockers (eg, atenolol, pindolol, propranolol, metoprolol). These slow the heart,
reducing how hard it has to work
Ranolazine. The exact way it exerts its antianginal effect is not known but may be through
inhibition of ion channels during cardiac repolarization.
Vasodilators: Drugs causing dilation (widen) of blood vessels allowing blood to flow
more easily through. Vasodilators keep your arteries and veins from narrowing or contracting
(squeezing) shut.
You have two main types of blood vessels. Veins carry blood to your heart, while
arteries carry blood from your heart to the rest of your body.
Some drugs are:
1. alpha adrenergic blocking agents. Tolazoline, azapetine
Tolazoline hydrochloride:
It produces increase in the force of contraction of myocardium. It dilates peripheral
blood vessels.
2. beta adrenergic stimulant: isoxsuprine hydrochloride
isoxsuprine hydrochloride:
Used for central and peripheral vascular diseases.
3. anticoagulants: Anticoagulants are medicines that help prevent blood clots.
They're given to people at a high risk of getting clots, to reduce their chances of
developing serious conditions such as strokes and heart attacks. A blood clot is a seal
created by the blood to stop bleeding from wounds.
coumarin derivatives
4. Miscellaneous agents:nicotinic acid derivatives, papaverine
rinPapaverine
Methylnictotinate
: as creams for relieving pain in muscular rheumatism .
Sodium nitroprusside is a medication used in the management of acute hypertension. It is a
potent vasodilator and is administered as an IV infusion with intensive monitoring in place.
This medicine is a direct-acting vasodilator.
