heart block

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Heart block:

Heart block

Introduction :

Introduction Heart block is a problem that occurs with the heart's electrical system. This system controls the rate and rhythm of heartbeats. ("Rate" refers to the number of times your heart beats in a minute. "Rhythm" refers to the pattern of regular or irregular pulses produced when the heart beats over time .

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. With each heartbeat, an electrical signal spreads across the heart from the upper to the lower chambers. As it travels, the signal causes the heart to contract and pump blood. This process repeats with each new heartbeat. Heart block occurs if the electrical signal is slowed or disrupted as it moves from the upper to the lower chambers of the heart.

Types of heart block:

Types of heart block First degree:- 1) AVB is a rhythm in which the electrical impulse which leaves the SA node and travels through the atria, AV node, Bundle of His to purkinjie fibres is slowed down and takes longer than normal to arrive at its destination. The normal PR interval is 0.12- 0.20 seconds. A 1 AVBT is greater than 0.20 seconds. The cause ranges from coronary heart disease, inferior wall MI's, hyperkalemia , congenital abnormalities, and medications such as quinidine , digitalis , beta blockers, and calcium channel blockers. . .

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When the P-wave always precedes the QRS-complex but the PR-interval is prolonged over 0.2 s, first-degree atrioventricular block is diagnosed . When the P-wave always precedes the QRS-complex but the PR-interval is prolonged over 0.2 s, first-degree atrioventricular block is diagnosed.

Second degree heart block:

Second degree heart block In this type of heart block, electrical signals between the atria and ventricles are slowed to a large degree. Some signals don't reach the ventricles. Second-degree heart block is divided into two types: Mobitz type I and Mobitz type II. Mobitz Type I:- also known as Wenckebach's block), This arrhythmia is characterized by a progressive delay of the conduction at the AV node, until the conduction is completely blocked.

Mobitz Type II:

Mobitz Type II In second-degree Mobitz type II heart block, some of the electrical signals don't reach the ventricles. On an EKG, the QRS wave follows the P wave at a normal speed. Sometimes, though, the QRS wave is missing (when a signal is blocked). It is characterized by 2-4 P waves before each QRS.

Third-Degree Heart Block:

Third-Degree Heart Block In this type of heart block, none of the electrical signals reach the ventricles. This type also is called complete heart block or complete AV block. All electrical conduction from the atria are blocked at the AV junction, therefore, the atria and the ventricles beat independently from each other. On an EKG, the normal pattern is disrupted. The P waves occur at a faster rate that isn't coordinated with the QRS waves. Complete heart block can result in sudden cardiac arrest and death. A temporary pacemaker may be used to keep the heart beating until you get a long-term pacemaker.

Causes :

Causes Congenital- congenital heart block occurs in babies whose mothers have autoimmune diseases, such as lupus. People who have these diseases make proteins called antibodies that attack and damage the body's tissues or cells. In pregnant women, antibodies can cross the placenta. (The placenta is the organ that attaches the umbilical cord to the mother's womb.) These proteins can damage the baby's heart and lead to congenital heart block.

Acquired :

Acquired Many factors can cause acquired heart block. Examples include: Damage to the heart from a heart attack . This is the most common cause of acquired heart block. Coronary heart disease , also called coronary artery disease. Myocarditis (MI-o- kar -DI- tis ), or inflammation of the heart muscle. Heart failure . Rheumatic ( roo -MAT- ik ) fever. Cardiomyopathy (KAR-de-o-mi-OP-a-the), or heart muscle diseases.

Continua…:

Continua… Exposure to toxic substances and taking certain medicines—including digitalis, beta blockers, and calcium channel blockers—also may cause heart block. heart block that occurs after a heart attack or surgery may go away during recovery. Other diseases also may raise the risk of heart block. These include sarcoidosis and the degenerative muscle disorders Lev's disease and Lenegre's disease.

Symptoms :

Symptoms First-degree heart block rarely causes symptoms. Symptoms of second- and third-degree heart block include:- Fainting Dizziness or light-headedness Fatigue (tiredness) Shortness of breath Chest pain

Diagnostic evaluations :

Diagnostic evaluations 1) H/c- regarding family history and medical history. 2) P/E- the doctor will ask regarding Check your pulse to find out how fast your heart is beating Check for swelling in your legs or feet, which could be a sign of an enlarged heart or heart failure Look for signs of other diseases that could be causing heart rate or rhythm problems (such as coronary heart disease )

Contin….:

Contin …. 3) ECG- to help diagnose heart block. This simple test detects and records the heart's electrical activity. 4) Electrophysiology study- a thin, flexible wire is passed through a vein in your groin (upper thigh) or arm to your heart. The wire records your heart's electrical signals. 5) Blood tests. Blood tests check the level of substances in the blood, such as potassium or thyroid hormone, that can increase your chances of having an arrhythmia. 6)Chest x ray. A chest x ray is a painless test that creates pictures of the structures in your chest, such as your heart and lungs. This test can show whether the heart is enlarged

Conti…:

Conti… 7) Echocardiography (echo) provides information about the size and shape of your heart and how well your heart chambers and valves are working. transesophageal ( tranz - ih - sof -uh-JEE- ul ) echo, or TEE, is a special type of echo that takes pictures of the back of the heart through the esophagus (the passage leading from your mouth to your stomach). magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning of the heart. 8) Coronary angiography (an- jee -OG- ra -fee). Coronary angiography uses dye and special x rays to show the inside of your coronary (heart) arteries.

Conti….:

Conti…. 9) Implantable loop recorder. This device detects abnormal heart rhythms. Minor surgery is used to place this device under the skin in the chest area.

Management :

Management Medicines:- 1)The medicines used to slow a fast heart rate are beta blockers (such as metoprolol and atenolol ), calcium channel blockers (such as diltiazem and verapamil ), and digoxin (digitalis). 2) Antiarythmics -medicines used to restore an abnormal heartbeat to a normal rhythm are amiodarone , sotalol , flecainide , propafenone , dofetilide , ibutilide , quinidine , procainamide , and disopyramide . 3) Anticoagulants - Aspirin, warfarin (Coumadin ® ), and heparin are commonly used blood thinners.

Conti….:

Conti…. 4) arrhythmias are treated with a pacemaker . A pacemaker is a small device that's placed under the skin of your chest or abdomen to help control abnormal heart rhythms. 5) Surgery – CABG- This surgery improves blood supply to the heart muscle.

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