Cardiac ArrhythmiasCardiac Arrhythmias

Cardiac ArrhythmiasCardiac Arrhythmias Abnormal rate and or rhythm of the heart can be Abnormal rate and or rhythm of the heart can be

physiological or pathological, congenital or acquired, physiological or pathological, congenital or acquired, transient or chronic, self-limited or life threatening. For transient or chronic, self-limited or life threatening. For all of which ECG is essential to make a diagnosis.all of which ECG is essential to make a diagnosis.

((I) Tachyarrhythmia (increased H.R.):I) Tachyarrhythmia (increased H.R.): 1- Sinus tachycardia1- Sinus tachycardia: a physiological compensatory : a physiological compensatory

mechanism due to rapid discharge from S.A. node in mechanism due to rapid discharge from S.A. node in response to:response to:

A- Certain physiological events as crying, pain, A- Certain physiological events as crying, pain, anxiety and exercise.anxiety and exercise.

B- Certain pathological events as fever, shock, B- Certain pathological events as fever, shock, hypoxia, H.F. , anemia or hypoxia, H.F. , anemia or

C- Due to certain drugs as atropine, adrenaline or C- Due to certain drugs as atropine, adrenaline or theophylline.theophylline.

ECG shows tachycardia with normal "P", normal 1:1 AV ECG shows tachycardia with normal "P", normal 1:1 AV conduction and normal QRS.conduction and normal QRS.

2- Supra ventricular tachycardia2- Supra ventricular tachycardia "S.V.T."; the discharge is "S.V.T."; the discharge is from an abnormal mechanism proximal to the from an abnormal mechanism proximal to the bifurcation of "His" bundle. It is of 3 types:bifurcation of "His" bundle. It is of 3 types:

A- Paroxysmal S.V.T.: caused by "Re-entry" A- Paroxysmal S.V.T.: caused by "Re-entry" phenomenon through the AV node or through other phenomenon through the AV node or through other conducting pathways. SVT affects all ages from conducting pathways. SVT affects all ages from fetal life onward.fetal life onward.

The paroxysm occurs suddenly without an event cause or The paroxysm occurs suddenly without an event cause or follows an infection or a physical factor and usually follows an infection or a physical factor and usually occurs at rest. The H.R. is between 180 and 300 /min. occurs at rest. The H.R. is between 180 and 300 /min. short attacks for minutes or hours may be tolerated but short attacks for minutes or hours may be tolerated but prolonged and severe forms may lead to C.C.F.prolonged and severe forms may lead to C.C.F.

The attack may spontaneously terminate as suddenly as The attack may spontaneously terminate as suddenly as it began. Polyuria may occur due to release of atrial it began. Polyuria may occur due to release of atrial nitriuretic peptide.nitriuretic peptide.

Maneuvers that increase vagal tone (unilateral carotid Maneuvers that increase vagal tone (unilateral carotid sinus massage, valsalva maneuver, abdominal pressure, sinus massage, valsalva maneuver, abdominal pressure, pressure on the eye ball [not in young infants] and ice pressure on the eye ball [not in young infants] and ice pack on the face) may successfully terminate the attackpack on the face) may successfully terminate the attack

SVT may be precipitated by nasal decongestants SVT may be precipitated by nasal decongestants (sympathomimetics).(sympathomimetics).

ECG reveals a very fast rate, normal "P", normal 1:1 AV ECG reveals a very fast rate, normal "P", normal 1:1 AV conduction and normal QRS.conduction and normal QRS.

Some patients with SVT have WPW syndrome and are at Some patients with SVT have WPW syndrome and are at higher risk for sudden death from WPW syndrome.higher risk for sudden death from WPW syndrome.

During the paroxysm the ECG misses WPW picture which is During the paroxysm the ECG misses WPW picture which is in the form of short P-R and slow upstroke QRS (delta in the form of short P-R and slow upstroke QRS (delta wave).wave).

If the above measures fail I.V adenosine 0.05 mg/kg bolus If the above measures fail I.V adenosine 0.05 mg/kg bolus repeated every 2 min for several times.repeated every 2 min for several times.

When available DC cardioversionWhen available DC cardioversion Other drugs used in SVT include; Phenylphrine, Other drugs used in SVT include; Phenylphrine,

Edrophonium, Amiodarone, Quinidine, Procainamide, Edrophonium, Amiodarone, Quinidine, Procainamide, propranolol and Verapamil (not used in infants).propranolol and Verapamil (not used in infants).

After cessation of the acute paroxysm maintenance drugs After cessation of the acute paroxysm maintenance drugs as Digoxin (not in presence of WPW), Propranolol, as Digoxin (not in presence of WPW), Propranolol, Amiodarone, Verapamil, etcAmiodarone, Verapamil, etc…….should be used for 1 year. .should be used for 1 year.

Recurrences are common in older children and may Recurrences are common in older children and may indicate for radiofrequency ablation therapy.indicate for radiofrequency ablation therapy.

WPW syndromeWPW syndrome

B- Atrial flutter: a very uncommon form of B- Atrial flutter: a very uncommon form of tachyarrhythmia, caused by an abnormal atrial focus tachyarrhythmia, caused by an abnormal atrial focus discharging at a very high rate (300-500/min) discharging at a very high rate (300-500/min) producing atrial "sawtooth" flutter waves on ECG.producing atrial "sawtooth" flutter waves on ECG.

As the AV node can not transmit all these impulses a degree As the AV node can not transmit all these impulses a degree of AV block occurs.of AV block occurs.

ECG shows a regular sawtooth "P" waves and a regular QRS ECG shows a regular sawtooth "P" waves and a regular QRS complexes but there is one QRS for each 2 or 3 P waves.complexes but there is one QRS for each 2 or 3 P waves.

This conduction is rare in normal heart.This conduction is rare in normal heart. Treatment includes vagal maneuvers, adenosine and Treatment includes vagal maneuvers, adenosine and

synchronized DC cardioversion.synchronized DC cardioversion.

C- Atrial fibrillation: mostly seen in older children with C- Atrial fibrillation: mostly seen in older children with chronic rheumatic heart disease, usually mitral chronic rheumatic heart disease, usually mitral stenosis. Thyrotoxicosis may be the cause. It is stenosis. Thyrotoxicosis may be the cause. It is characterized by irregular discharges from atrial characterized by irregular discharges from atrial foci resulting in an irregular disorganized atrial rate foci resulting in an irregular disorganized atrial rate of 350-600/min. patients are liable to have of 350-600/min. patients are liable to have thromboemboli and stroke.thromboemboli and stroke.

The ventricular response is variable, resulting in a very The ventricular response is variable, resulting in a very irregular beating.irregular beating.

ECG shows:ECG shows: Absent "P" waves (irregular base lines)Absent "P" waves (irregular base lines) Irregular P-R intervals (irregular ventricular Irregular P-R intervals (irregular ventricular

contractions)contractions) Normal shapes QRS complex.Normal shapes QRS complex.

Treatment is by digitalization which restores the Treatment is by digitalization which restores the ventricular rate to normal although the atrial fibrillation ventricular rate to normal although the atrial fibrillation usually persists, followed by Amiodaroneusually persists, followed by Amiodarone Warfarin. Warfarin.

3- Ventricular tachyarrhythmia3- Ventricular tachyarrhythmia: the rapid heart rate : the rapid heart rate originates from abnormal ventricular mechanisms.originates from abnormal ventricular mechanisms.

Two main forms are known:Two main forms are known:A- A- Ventricular tachycardiaVentricular tachycardia; a serious condition which may ; a serious condition which may

change to fatal ventricular fibrillation, predisposed by change to fatal ventricular fibrillation, predisposed by myocarditis, cardiomyopathy, digoxin toxicity, hypoxia myocarditis, cardiomyopathy, digoxin toxicity, hypoxia or severe electrolyte imbalance.or severe electrolyte imbalance.

Clinically there is tachycardia Clinically there is tachycardia syncope and sudden syncope and sudden death may occur. ECG shows rapid wide QRS not death may occur. ECG shows rapid wide QRS not preceded by P waves.preceded by P waves.

I.v. lidocaine is essential to prevent fibrillation and death.I.v. lidocaine is essential to prevent fibrillation and death.

B- B- Ventricular fibrillationVentricular fibrillation: a potentially fatal dysrhythmia : a potentially fatal dysrhythmia which cause death within few minutes unless which cause death within few minutes unless immediate resuscitative measures ere provided.immediate resuscitative measures ere provided.

Clinically the patient suddenly loses consciousness with Clinically the patient suddenly loses consciousness with no detectable heart beat and the ECG shows total no detectable heart beat and the ECG shows total disorganization with absent QRS. disorganization with absent QRS.

Immediate cardiac massage, i.v. amiodarone or Immediate cardiac massage, i.v. amiodarone or lidocaine,intracardiac adrenaline and artificial ventilation lidocaine,intracardiac adrenaline and artificial ventilation + cardioversion when available.+ cardioversion when available.

(II) Bradyarrhythmia:(II) Bradyarrhythmia: Bradycardia is considered to be present when the heart Bradycardia is considered to be present when the heart

rate is less than the lower normal limit for age .rate is less than the lower normal limit for age . The lower limit of heart rate in awake state is:The lower limit of heart rate in awake state is:Newborn 90/min.Some what less during sleepNewborn 90/min.Some what less during sleepInfant 100/min.Infant 100/min.Young children 80/min.Young children 80/min.Older children 60/min.Older children 60/min. Bradyarrhythmias include:Bradyarrhythmias include:

1- Sinus bradycardia (S.B.);1- Sinus bradycardia (S.B.); characterized by abnormally characterized by abnormally slow heart rate caused by discharge from S.A. node.slow heart rate caused by discharge from S.A. node.

Sinus bradycardia may be physiological (during sleep Sinus bradycardia may be physiological (during sleep and in athletes), pathological (syncope or raised intra- and in athletes), pathological (syncope or raised intra- cranial pressure) or caused by drugs (Digoxin or cranial pressure) or caused by drugs (Digoxin or propranolol)propranolol)

Clinically there is bradycardia which increases with Clinically there is bradycardia which increases with exertion (crying), a point which differentiates sinus exertion (crying), a point which differentiates sinus bradycardia from AV block.bradycardia from AV block.

ECG shows a slow rate but normal P-QRS-T complexes.ECG shows a slow rate but normal P-QRS-T complexes.

2- Atrioventricular block;2- Atrioventricular block; it is of three types: it is of three types:A- First degree AV block: prolonged P-R interval but all A- First degree AV block: prolonged P-R interval but all

the atrial impulses are conducted to the ventricle.the atrial impulses are conducted to the ventricle.B- Second degree; failure of conduction of some of the B- Second degree; failure of conduction of some of the

atrial impulses to the ventricle.atrial impulses to the ventricle. It is subdivided in to two forms:It is subdivided in to two forms: Mobitz type I (wenckebach);Mobitz type I (wenckebach); in which the P-P interval in which the P-P interval

remains constant, but there is progressive increase of the remains constant, but there is progressive increase of the P-R interval until a "P" wave is not conducted. After this P-R interval until a "P" wave is not conducted. After this dropped beat the cycle starts again with a short P-R dropped beat the cycle starts again with a short P-R interval.interval.

Mobitz type IIMobitz type II; P-R interval remains constant, but an ; P-R interval remains constant, but an occasional atrial beat does not conduct to the ventricle. occasional atrial beat does not conduct to the ventricle. Syncope may occur and the conduction may change to Syncope may occur and the conduction may change to complete AV block.complete AV block.

C- Third degree (complete heart block): no atrial C- Third degree (complete heart block): no atrial impulse reaches the ventricles.impulse reaches the ventricles.

The cause may be;The cause may be; Congenital, usually associated with maternal SLE.Congenital, usually associated with maternal SLE. Acquired; digixin, post cardiac surgery, or bacterial Acquired; digixin, post cardiac surgery, or bacterial

endocarditis.endocarditis. Clinically; most are asymptomatic, heart rate is around Clinically; most are asymptomatic, heart rate is around

50/min, may increase by 10-20 on exercise or atropine.50/min, may increase by 10-20 on exercise or atropine. Symptoms include fatigue, exercise intolerance, syncope Symptoms include fatigue, exercise intolerance, syncope

(stokes-Adams attacks) and rarely sudden death may (stokes-Adams attacks) and rarely sudden death may occur.occur.

Systolic murmurs are commonly heared. Cardiomegaly Systolic murmurs are commonly heared. Cardiomegaly and elevated blood pressure may be detected.and elevated blood pressure may be detected.

ECG: QRS duration may be prolonged.ECG: QRS duration may be prolonged. Prognosis of the congenital complete heart block is good. Prognosis of the congenital complete heart block is good.

Some who have exercise intolerance, progressive Some who have exercise intolerance, progressive cardiomegaly or Stokes-Adams attacks need implantation cardiomegaly or Stokes-Adams attacks need implantation of the permanent cardiac pace maker.of the permanent cardiac pace maker.

3- Sick Sinus Syndrome "SSS"3- Sick Sinus Syndrome "SSS" This form of Bradyarrhythmia usually follows cardiac surgery, This form of Bradyarrhythmia usually follows cardiac surgery,

myocarditis, myocardial ischemia or cardiomyopathy. SSS is myocarditis, myocardial ischemia or cardiomyopathy. SSS is characterized by profound unresponsive sinus bradycardia with characterized by profound unresponsive sinus bradycardia with or without periods of tachycardia (bradycardia- tachycardia or without periods of tachycardia (bradycardia- tachycardia syndrome) manifests as dizziness and syncope. In symptomatic syndrome) manifests as dizziness and syncope. In symptomatic cases drugs as digoxin or ventricular pacemaker are necessary.cases drugs as digoxin or ventricular pacemaker are necessary.

4- Asystole;4- Asystole; complete cessation of cardiac contraction, (flat ECG) complete cessation of cardiac contraction, (flat ECG) may follow bradycardias or results from sever hypoxia, may follow bradycardias or results from sever hypoxia, acidosis, shock, hypothermia, electrolyte disturbances or acidosis, shock, hypothermia, electrolyte disturbances or hypovolemia. Stressful procedures as lumber puncture, hypovolemia. Stressful procedures as lumber puncture, intubation or intra venous canulation may cause cardiac intubation or intra venous canulation may cause cardiac arrest.arrest.

Extrasystoles (premature beat): these are mostly benign and Extrasystoles (premature beat): these are mostly benign and occur in normal children. They may also accompany various occur in normal children. They may also accompany various organic (inflammation, ischemia, fibrosis) heart disease or be organic (inflammation, ischemia, fibrosis) heart disease or be drug induce (digoxin)drug induce (digoxin)

They result from isolated discharge from an ectopic atrial or They result from isolated discharge from an ectopic atrial or ventricular focus.ventricular focus.

The atrial extrasystoles are shown on ECG as;The atrial extrasystoles are shown on ECG as; Abnormally shaped "P" waveAbnormally shaped "P" wave Normal QRSNormal QRS No compensatory pauseNo compensatory pause

The ventricular extrasystoles are shown on ECG by:The ventricular extrasystoles are shown on ECG by: Wide bizarre QRS, inverted "T" and a compensatory pause.Wide bizarre QRS, inverted "T" and a compensatory pause. Long Q-T SyndromeLong Q-T Syndrome "LQTS""LQTS" This is a rare condition characterized by prolonged QT This is a rare condition characterized by prolonged QT

interval, syncopal attacks. Nerve deafness, hemiplegia, interval, syncopal attacks. Nerve deafness, hemiplegia, petit-mal may be present. LQTS may be a cause of SUIDS.petit-mal may be present. LQTS may be a cause of SUIDS.

There may be an abnormality in the sympathetic There may be an abnormality in the sympathetic innervation of the myocardium.innervation of the myocardium.

LQTS may be familial (both A.R. and A.D. are known) or LQTS may be familial (both A.R. and A.D. are known) or acquired due to:acquired due to:

Drugs as phenothiazine ,Hypokalemia, hypocalcemia or Drugs as phenothiazine ,Hypokalemia, hypocalcemia or hypomagnisemia ,Hypothermia ,Cerebrovascular diseaseshypomagnisemia ,Hypothermia ,Cerebrovascular diseases

or Neck surgery.or Neck surgery. TreatmentTreatment includes propranolol, di-phenyl hydantoin and includes propranolol, di-phenyl hydantoin and

left stellate ganglionectomy.left stellate ganglionectomy. The mortality is high (75%) without treatment.The mortality is high (75%) without treatment.

Cardiomyopathy “CMPCardiomyopathy “CMP”” This entity means myocardial dysfunction, which could be familial This entity means myocardial dysfunction, which could be familial

or results from different other diseases like muscle dystrophy, or results from different other diseases like muscle dystrophy, glycogen storage disease , hemochromatosis etc.glycogen storage disease , hemochromatosis etc.

C.M.P is of 3 distinctive forms :C.M.P is of 3 distinctive forms :1. Congestive (dilated) C.M.P ; characterized by CCF ,arrhythmias , 1. Congestive (dilated) C.M.P ; characterized by CCF ,arrhythmias ,

mitral or tricuspid murmurs and emboli.mitral or tricuspid murmurs and emboli. X-ray shows cardiomegalyX-ray shows cardiomegaly Prognosis is bad.Prognosis is bad.2. Restrictive C.M.P: also presents as C.C.F. with cardiomegaly , 2. Restrictive C.M.P: also presents as C.C.F. with cardiomegaly ,

distant heart sounds , but usually no murmurs .distant heart sounds , but usually no murmurs . ECG shows low voltage, arrhythmias, ST and T changes.ECG shows low voltage, arrhythmias, ST and T changes.3. Obstructive : characterized by obstruction to left ventricle and 3. Obstructive : characterized by obstruction to left ventricle and

interventricular septum.interventricular septum.It is also termed Idiopathic Hypertrophic It is also termed Idiopathic Hypertrophic Subaortic Stenosis (IHSS)Subaortic Stenosis (IHSS)

30 % of cases of IHSS are familial but usually appears after 30 % of cases of IHSS are familial but usually appears after childhood.childhood.

Management :Management : In general there is no specific treatment for C.M.P. In general there is no specific treatment for C.M.P. Anti failure (vasodilator , Diuretics and ACE inhibitor )Anti failure (vasodilator , Diuretics and ACE inhibitor ) Anticoagulant when emboli are suspected Anticoagulant when emboli are suspected Beta blockers are used for hypertrophic CMP Beta blockers are used for hypertrophic CMP Anti arrhythmic agent.Anti arrhythmic agent. Surgical myotomy in some forms of localized obstruction. Surgical myotomy in some forms of localized obstruction. Repair or replacement of mitral valve may be needed. Repair or replacement of mitral valve may be needed. Cardiac transplant in terminal cases.Cardiac transplant in terminal cases.

Myocarditis Myocarditis Causes of which are numerous including:Causes of which are numerous including: Different virusesDifferent viruses Bacterial toxinsBacterial toxins Parasitic infection.Parasitic infection. Fungal infection.Fungal infection. Collagen vascular diseases.Collagen vascular diseases. Metabolic and nutritional diseases.Metabolic and nutritional diseases. Neuromuscular disorders.Neuromuscular disorders. IEMIEM Blood disorders.Blood disorders. Drugs.Drugs. Corornary artery damage.Corornary artery damage.

Viral myocarditis is, however the most common form, Viral myocarditis is, however the most common form, symptoms of which are usually abrupt especially in symptoms of which are usually abrupt especially in neonates with unexplained breathlessness, gallop rhythm, neonates with unexplained breathlessness, gallop rhythm, shock ,C.C.F. &arrhythmia. ECG shows ; low voltage , ST shock ,C.C.F. &arrhythmia. ECG shows ; low voltage , ST and T changes , X-ray shows cardiomegaly.and T changes , X-ray shows cardiomegaly.

Treatment :Treatment : O2O2 Bed rest Bed rest Anti failureAnti failure Steroid especially in presence of cardiovascular collapse Steroid especially in presence of cardiovascular collapse

and conduction disturbance.and conduction disturbance.