Heart block

Heart block

1.          

2. P RE S E N T E D B Y MR. ROMAN BAJRANG RE LI A N C E IN ST I T U T E O F NURSING TOPIC HEART BLOCK

3. A heart block is a disease in the electrical system of the heart . This is opposed to coronary artery disease , which is disease of the blood vessels of the heart. While coronary artery disease can cause angina (chest pain) or myocardial infarction (heart attack), heart block can cause light headedness, syncope ( fainting ), and palpitations . Heart block is a delay in the conduction of electrical current as it passes through the atrioventricular node, bundle of His, or both bundle branches, all of which are located between the atria and the ventricles. INTRODUCTION

4. DEFINITION -

5. TYPES

6. SECOND DEGREE A.V. BLOCK Second - degree atrioventricular ( AV ) block , or second - degree heart block , is a disorder characterized by disturbance, delay, or interruption of atrial impulse conduction to the ventricles through the atrioventricular node (AVN) and bundle of His. Electrocardiographically, some P waves are not followed by a QRS complex.

7. Con………… No electrical messages get through. The rate and rhythm of your heartbeat is very slow or it may even stop entirely. This type of heart block can be fatal.

8. THIRED DEGREE A.V.BLOCK Third - degree atrioventricular block ( AV block ) is a medical condition in which the nerve impulse generated in the sinoatrial node (SA node) in the atrium of the heart can not propagate to the ventricles. Because the impulse is blocked, an accessory pacemaker in the lower chambers will typically activate the ventricles .

9. ETIOLOGY-

10. E T I O LO G Y - First degree heart block It may sound contradictory, but being very fit is one of the most common causes of first degree heart block. For example, the condition is widespread among elite long distance runners. This is because vigorous and prolonged exercise can enlarge the heart muscles, which causes mild disruption to the electrical signals of the heart. Other causes of first degree heart block include: myocarditis – inflammation of the heart muscle low levels of potassium in the blood ( hypokalaemia ) low levels of magnesium in the blood ( hypomagnesemia) Certain medications can also cause first degree heart block, including: medications for treating abnormal heart rhythms (antiarrhythmics), such as disopyramide medications that are used to treat high blood pressure, such as calcium channel blockers digoxin – a medication that is used to treat heart failure

11. Second degree heart block As with first degree heart block, athletes can develop second degree heart block for the reasons discussed above. Some children who are born with congenital heart disease (heart defects that are present at birth) can also develop second degree heart block. Other causes of second degree heart block include: damage that develops during a heart attack Lyme’s disease – a bacterial infection that is spread by tics certain medications, such as calcium-channel blockers (used to treat high blood pressure ), amiodarone (used to treat abnormal heart rhythms) and pentamidine (used to treat some types of pneumonia)

12. Third degree heart block (congenital) A large proportion of congenital third degree heart block cases develop in mothers who have an autoimmune condition, such as lupus (a long-term condition that causes inflammation in the body's tissues). An autoimmune condition is where the immune system mistakenly attacks healthy cells and tissue. It is thought that the immune system mistakes the unborn baby for a foreign object (such as a virus) and sends antibodies to attack it. The antibodies damage the heart. Some children with congenital heart disease are also born with third degree heart block.

13. Third degree heart block (acquired) Many cases of third degree heart block are caused by damage to the muscles of the heart. The heart muscle can become damaged for a number of reasons, including: as a complication of heart surgery – this is thought to be one of the most common causes coronary heart disease – a condition where the heart does not receive enough blood as a complication of radiotherapy (a treatment for conditions such as cancer, thyroid disorders and some blood disorders) as a result of a serious infection, such as diphtheria (a bacterial infection that can cause inflammation of the heart) or rheumatic fever (a bacterial infection that damages the valves of the heart) poorly controlled high blood pressure (hypertension) cancer that spread from another part of the body into the heart a penetrating trauma to the chest, such as a stab wound or gunshot wound

14. A number of medications can also cause third degree heart block, including: digoxin calcium-channel blockers beta blockers – used to treat high blood pressure (hypertension) tricyclic antidepressants – an older type of antidepressant clonidine – used to treat a sudden, sharp rise in blood pressure (hypertensive crisis

15. C O N…. Causes Some people are born with heart block. In others, it develops later in life. If you’re born with it, it’s called congenital heart block. Causes include: AUTOIMMUNE DISEASE . Diseases, such as lupus , can be passed by your mother in certain proteins through the umbilical cord. BIRTH DEFECT . heart may not have developed correctly in the womb. Doctors often don’t know what causes these birth defects. If you have heart block that you weren’t born with, doctors call it “acquired” heart block. It’s the most common type. Causes include:

16. Con…………… Certain types of surgery that affect the heart’s electrical system Changes in your genes Damage from a heart attack Heart issues like clogged arteries , inflammation of the heart muscle, and heart failure Muscle disorders or other diseases Some medicines

17. PATHOPHYSIOLOGY

18. The electrical current stimulates cardiac contraction that causes ejection of blood from the left ventricle into the aorta which results in an adequate supply of blood, oxygen, and other nutrients to the brain and vital organs. The electrical current may be halted by diseases that destroy the specialized conducting tissue in the AV node or lower in the bundle of His; the current fails to reach the ventricle and no cardiac contraction occurs (asystole). With complete heart block the heart rate is usually less than 30 beats per minute followed by several seconds of no heartbeats and possible loss of consciousness Due to etiological factors such as autoimmune d/s radiation, birth defects

19. block of the conduction of electrical impulses from the atrium through the main electrical tunnel (AV node) that transmits the impulses to the ventricle in this condition, the ventricles fail to contract, as there is no electrical stimulus (asystole) or the ventricle quivers (ventricular fibrillation) and loss of consciousness occurs. The most dramatic manifestation of asystole is severe cerebral ischemia, heart block

20. CLINICAL M A NIF E STA T ION

21. CLINICAL MANIFESTATION First-degree AV block has no symptoms Second-degree AV block of type I- is characterised by the temporary absence of a heart beat described by the patient as a break. Second-degree AV block of type II-the patient might have bradycardia, a decrease in the ability to adapt to exertion, rarely syncope. Third-degree AV block -can have one of the following clinical manifestations: Severe bradycardia Syncope Cardiac failure symptoms Rare, regular arterial pulse

22. Common C.M. Symptoms symptoms depend on the type of heart block you have. If you have first degree, you may not have any at all. Second-degree symptoms may include: Chest pain Dizziness Fainting Fatigue Nausea Shortness of breath The feeling that your heart skips a beat Third-degree heart block needs immediate medical attention. Call 911 for any: Cardiac arrest Dizziness Fainting New, severe tiredness Irregular heartbeat or new palpitations

23. DIAGNOSTIC EVALUATION - Electrocardiogram (ECG) —a test that records the heart's activity by measuring electrical currents through the heart muscle Echocardiogram —a test that uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart

24. Troponin Serum An elevated troponin is in general concerning for heart damage until proven otherwise. It can be from a heart attack due to a blockage or due to other conditions that place strain on the heart such as heart failure or critical illness. As discussed below there are other, non cardiac causes of a troponin elevation.

25. HOLTER MONITOR Holter Monitor A holter monitor is a small, portable machine that you wear for 24 hours. It enables continuous recording of your ECG as you go about your daily activities. You will be asked to keep a diary log of your activities and symptoms. This monitor may detect arrhythmias that might not show up on a resting EKG that only records for a few seconds.

26. 24-hour ambulatory blood pressure monitoring used? Ambulatory BP monitoring provides additional information about how your changes in BP may correlate with your daily activities and sleep patterns. The United States Preventive Services Task Force (USPSTF) now recommends confirming a diagnosis of hypertension with ambulatory BP monitoring.

27. C O N … . . Twenty-four-hour ambulatory blood pressure monitoring is a way of measuring and managing high blood pressure (hypertension). Hypertension is a blood pressure measurement in which the systolic (upper) blood pressure is at or above 140 and the diastolic (lower) blood pressure is at or above 90.

28. EXERCISE STRESS TEST The exercise stress (treadmill) test enables physicians to record your heart's electrical activity which may not occur at rest.

29. MAGNETIC SOURCE IMAGING Magnetic source imaging (MSI) is used as an overlay to magnetic resonance imaging (MRI). The device senses weak magnetic fields generated by heart muscle tissue and localizes the arrhythmia non- invasively to save time during the invasive study.

30. MANAGEMENT

31. TREATMENT Medication - alters the properties of ion movement across cardiac membranes and affect automaticity as well as the rate and duration of depolarisation and repolarisation. Class I ( blocks the ions of sodium) Procainamide, Quinidine Lidocaine, Tocainide Flecainide, Propafenone Class II (indirectly blocks the ions of calcium) Atenolol, Metoprolol,Propanolol Class III ( blocks the ions of potassium) Amiodarone, Sotalol, Ibutilide Class IV ( blocks the ions of calcium) Diltiazem, Verapamil

32. Digitalis (enhances vagal tone, slows heart rate and AV conduction Pacemaker implantation - should be performed in any patient with symptomatic bradycardia and irreversible second or third degree AV block regardless of the cause or level of block in the conducting system. Implantable defibrillators – that detect lethal rhythms and apply electric shocks to convert to normal sinusal rhythm( for those at high risk) Treatment for this tpe of dysrhithmias ( AV blocks) centers on maintaining adequate cardiac output, providing antiarhytmic drugs when needed and managing the underlying pathological process. OTHER :-

33. First-degree heart block (also called first-degree AV block). Treatment: First-degree heart block generally requires no treatment, although some people may need to be treated for an underlying electrolyte imbalance. If medications are causing the condition, a physician may revaluate the dosage or advise the patient to stop taking it. Medications should not be adjusted without consulting a medical professional. A physician may recommend follow-up with a cardiologist to be sure that the patient does not develop a more severe form of heart block. Follow-up is particularly important if first-degree heart block developed as a result of a past heart attack or myocarditis. In patients with severe heart failure and first-degree heart block, implantation of a pacemaker may sometimes improve cardiac performance. further treatment is generally unnecessary and prognosis is excellent.

34. Type I second-degree heart block (also known as Mobitz Type I second-degree AV block or Wenckebach AV block). Treatment: Type I second-degree heart block is generally treated by addressing any underlying conditions that are contributing to it. Temporary pacing and/or medication (e.g., atropine) may be required if the heartbeat is too slow, but a permanent pacemaker is generally not necessary unless the condition worsens. Type II second-degree heart block (Mobitz Type II second- degree AV block) Treatment: Type II second-degree heart block often produces noticeable symptoms and carries a significant risk of potentially life- threatening complications. Therefore, treatment is very important. A physician may administer medications (e.g., atropine) and recommend the implantation of a permanent pacemaker . If the condition worsens to third-degree heart block, then a temporary pacemaker wire may be needed during the medical crisis until a permanent pacemaker can be inserted.

35. Third-degree heart block (also known as complete heart block or complete AV block) Treatment: Third-degree heart block patients almost always require an artificial pacemaker to better regulate the electrical activity of the heart. If a medical crisis occurs before the pacemaker can be implanted, then a temporary pacemaker wire may be used to keep the heart beating. Most patients who are diagnosed with complete heart block will require placement of a permanent pacemaker , unless a treatable cause is identified and corrected.. Bundle Branch Block is when electrical impulses are slowed or blocked as they travel through specialized conducting tissue in the ventricles.

36. COMPLICATION Complications of a second degree heart block include: Angina Fainting Heart attack Stroke Third-degree heart block can lead to decreased cardiac output, circulatory impairment, heart failure and SCD. Other complications may include excessive urea in the blood (uremia) and low blood hemoglobin ( anemia ). Complications from pacemaker insertion include infection, medication reaction, and failure of the pacemaker.