Sick sinus syndrome

Cardiovascular

Clinicals - History

Fact Explanation
Common in the elderly age group but may rarely maybe congenital Sick sinus syndrome (SSS) is characterized by sinus node dysfunction with an atrial rate which is inappropriate for physiologic requirements. This condition is most common in the elderly but can occur in persons of all ages, including neonates. The mean age of patients with SSS is 68 years, and males and females are affected equally. sinus node malfunctions can result in several different abnormalities and they are inappropriate bradycardia, inappropriate tachycardia, Tachy- Brady syndrome and sinus pause or sinus arrest. Most cases of sick sinus syndrome are idiopathic, and the cause can be related to multiple factors. Age related degenerative fibrosis of nodal tissue is the most common cause of intrinsic changes in the sinoatrial node that lead to sick sinus syndrome. There are other certain conditions can cause these intrinsic changes as well such as in heart failure and atrial fibrillation where remodeling of the sinoatrial node occurs. Also certain infiltrative disease processes, including connective tissue diseases, hemochromatosis, sarcoidosis, and amyloidosis, may also cause intrinsic dysfunction of the sinoatrial node. Atherosclerotic changes of the sinus node artery, which originates from the proximal right coronary artery may contribute to chronic ischemia and subsequent fibrosis of the sinoatrial node is regarded as a minor cause. There also are extrinsic causes of sinus node dysfunction and conditions that can cause this problem in children. Extrinsic factors are pharmacologic agents such as beta blockers, calcium channel blockers, digoxin, sympatholytic medications, antiarrhythmic medications, and lithium, metabolic disturbances such as hyperkalemia, hypokalemia, and hypocalcemia, and autonomic dysfunction. There's a congenital SSS as well due to recessive SCN5A mutations Common in the elderly age group but may rarely maybe congenital
Sick sinus syndrome (SSS) is characterized by sinus node dysfunction with an atrial rate which is inappropriate for physiologic requirements. This condition is most common in the elderly but can occur in persons of all ages, including neonates. The mean age of patients with SSS is 68 years, and males and females are affected equally. sinus node malfunctions can result in several different abnormalities and they are inappropriate bradycardia, inappropriate tachycardia, Tachy- Brady syndrome and sinus pause or sinus arrest. Most cases of sick sinus syndrome are idiopathic, and the cause can be related to multiple factors. Age related degenerative fibrosis of nodal tissue is the most common cause of intrinsic changes in the sinoatrial node that lead to sick sinus syndrome. There are other certain conditions can cause these intrinsic changes as well such as in heart failure and atrial fibrillation where remodeling of the sinoatrial node occurs. Also certain infiltrative disease processes, including connective tissue diseases, hemochromatosis, sarcoidosis, and amyloidosis, may also cause intrinsic dysfunction of the sinoatrial node. Atherosclerotic changes of the sinus node artery, which originates from the proximal right coronary artery may contribute to chronic ischemia and subsequent fibrosis of the sinoatrial node is regarded as a minor cause. There also are extrinsic causes of sinus node dysfunction and conditions that can cause this problem in children. Extrinsic factors are pharmacologic agents such as beta blockers, calcium channel blockers, digoxin, sympatholytic medications, antiarrhythmic medications, and lithium, metabolic disturbances such as hyperkalemia, hypokalemia, and hypocalcemia, and autonomic dysfunction. There's a congenital SSS as well due to recessive SCN5A mutations
Asymptomatic Many people with early or mild SSS have no symptoms and apparently healthy Asymptomatic
Many people with early or mild SSS have no symptoms and apparently healthy
Palpitations Due to abnormal sensation of the heart beat which occurs during spells of tachycardia, bradycardia and tachy-brady syndrome Palpitations
Due to abnormal sensation of the heart beat which occurs during spells of tachycardia, bradycardia and tachy-brady syndrome
syncope, pre-syncope, or light-headedness Due to inability of the heart to pump sufficient blood to the brain and resultant cerebral hypoperfusion, because of a too slow or too fast heart rate. This occurs in 50% of people and this is a form of neuro-cardiogenic syncope. syncope, pre-syncope, or light-headedness
Due to inability of the heart to pump sufficient blood to the brain and resultant cerebral hypoperfusion, because of a too slow or too fast heart rate. This occurs in 50% of people and this is a form of neuro-cardiogenic syncope.
fatigue and Weakness Due to inadequate blood supply from the heart to meet the physiological needs of the body. fatigue and Weakness
Due to inadequate blood supply from the heart to meet the physiological needs of the body.
Confusion and dementia Due to insufficient blood supply to the brain due to extreme tachycardia or bradycardia Confusion and dementia
Due to insufficient blood supply to the brain due to extreme tachycardia or bradycardia
Angina This symptom develops when there's inadequate blood supply to the heart due to blocked arteries or because of erratic heart beat as in SSS. Angina
This symptom develops when there's inadequate blood supply to the heart due to blocked arteries or because of erratic heart beat as in SSS.
Disturbed sleep The erratic heart rhythm may interfere with sleep which makes people wake up at night. Disturbed sleep
The erratic heart rhythm may interfere with sleep which makes people wake up at night.
Hemipariesis, Aphasia and Cerebrovascular accident like manifestations Due to thrombo-embolism phenomena resulting from arrhythmia especially in the presence of bradycardia-
tachycardia syndrome (alternating brady-
arrhythmias and tachyarrhythmias), which may be related to dysrhythmia-induced emboli
Hemipariesis, Aphasia and Cerebrovascular accident like manifestations
Due to thrombo-embolism phenomena resulting from arrhythmia especially in the presence of bradycardia-
tachycardia syndrome (alternating brady-
arrhythmias and tachyarrhythmias), which may be related to dysrhythmia-induced emboli
ankle swelling, and other features suggestive of congestive cardiac failure Due to persistent arrhythmia, and angina, ultimately congestive cardiac failure may develop due to increased workload by the heart. ankle swelling, and other features suggestive of congestive cardiac failure
Due to persistent arrhythmia, and angina, ultimately congestive cardiac failure may develop due to increased workload by the heart.
Flushing of the face Due to associated tachycardia there can be flushing of face Flushing of the face
Due to associated tachycardia there can be flushing of face
Retrosternal pressure Due to pounding of the heart associated with tachycardia, tachy-brady syndrome Retrosternal pressure
Due to pounding of the heart associated with tachycardia, tachy-brady syndrome

Clinicals - Examination

Fact Explanation
Flushing of the face Due to associated tachycardia Flushing of the face
Due to associated tachycardia
Tachycardia, Bradycardia or spells of Tachy-Bradycardia, long pauses without a heart beat There's tachycardia, Bradycardi, Tachy-Brady syndrome, sinus arrest in the clinical spectrum of the disease Tachycardia, Bradycardia or spells of Tachy-Bradycardia, long pauses without a heart beat
There's tachycardia, Bradycardi, Tachy-Brady syndrome, sinus arrest in the clinical spectrum of the disease
Aphasia, Hemipareisis and cerebrovascular accident like manifestations Due to thrombo-embolism phenomena resulting from arrhythmia especially in the presence of bradycardia-
tachycardia syndrome (alternating brady-
arrhythmias and tachyarrhythmias), which may be related to dysrhythmia-induced emboli
Aphasia, Hemipareisis and cerebrovascular accident like manifestations
Due to thrombo-embolism phenomena resulting from arrhythmia especially in the presence of bradycardia-
tachycardia syndrome (alternating brady-
arrhythmias and tachyarrhythmias), which may be related to dysrhythmia-induced emboli
Confusion Due to insufficient blood supply to the brain due to extreme tachycardia or bradycardia Confusion
Due to insufficient blood supply to the brain due to extreme tachycardia or bradycardia
Signs of congestive cardiac failure such as ankle swelling, elevated jugular venous pulse, hepatomgealy Due to persistent arrhythmia, and angina, ultimately congestive cardiac failure may develop due to increased workload by the heart. Signs of congestive cardiac failure such as ankle swelling, elevated jugular venous pulse, hepatomgealy
Due to persistent arrhythmia, and angina, ultimately congestive cardiac failure may develop due to increased workload by the heart.

Investigations - Diagnosis

Fact Explanation
Electrocardiogram The diagnosis of sick sinus syndrome requires electrocardiographic findings of bradyarrhythmias, such as sinus bradycardia, sinoatrial pause of three seconds or more, sinoatrial exit block, or sinus arrest. But findings often are normal in patients with sick
sinus syndrome, particularly early in the disease course. Even though bradyarrhythmias are required for the
diagnosis, supraventricular tachyarrhythmias are present in around 50 % of patients with sick sinus syndrome. Episodes of alternating tachyarrhythmias and bradyarrhythmias are known as tachycardia- bradycardia, or tachy-brady, syndrome. The most common tachyarrhythmias are atrial fibrillation or flutter and these tachyarrhythmias are more common in older patients with advanced sinoatrial nodal disease in whom sino -
atrial node fibrosis is seen.
Electrocardiogram
The diagnosis of sick sinus syndrome requires electrocardiographic findings of bradyarrhythmias, such as sinus bradycardia, sinoatrial pause of three seconds or more, sinoatrial exit block, or sinus arrest. But findings often are normal in patients with sick
sinus syndrome, particularly early in the disease course. Even though bradyarrhythmias are required for the
diagnosis, supraventricular tachyarrhythmias are present in around 50 % of patients with sick sinus syndrome. Episodes of alternating tachyarrhythmias and bradyarrhythmias are known as tachycardia- bradycardia, or tachy-brady, syndrome. The most common tachyarrhythmias are atrial fibrillation or flutter and these tachyarrhythmias are more common in older patients with advanced sinoatrial nodal disease in whom sino -
atrial node fibrosis is seen.
24 hour Holter monitoring When electrocardiography can not yield a
diagnosis, prolonged cardiac monitoring should done. This can be done in the hospital
via telemetry monitoring or on an outpatient basis with a 24- to 48-hour Holter monitor. It can be repeated if the diagnosis is uncertain.
24 hour Holter monitoring
When electrocardiography can not yield a
diagnosis, prolonged cardiac monitoring should done. This can be done in the hospital
via telemetry monitoring or on an outpatient basis with a 24- to 48-hour Holter monitor. It can be repeated if the diagnosis is uncertain.
external continuous or event monitors If clinical suspicion of arrhythmia remains high and Holter monitoring results are not conclusive, external continuous or event monitors can be used in patients for for weeks at a time external continuous or event monitors
If clinical suspicion of arrhythmia remains high and Holter monitoring results are not conclusive, external continuous or event monitors can be used in patients for for weeks at a time
implantable loop recorder If above investigations are inconclusive this can be done for months at a time. implantable loop recorder
If above investigations are inconclusive this can be done for months at a time.
Electrophysiologic studies These are useful in the evaluation of sick sinus syndrome in whom sick sinus syndrome is strongly suspected but no arrhythmia has been demonstrated that correlates with symptoms after prolonged
cardiac monitoring
Electrophysiologic studies
These are useful in the evaluation of sick sinus syndrome in whom sick sinus syndrome is strongly suspected but no arrhythmia has been demonstrated that correlates with symptoms after prolonged
cardiac monitoring
exercise treadmill testing It's been found that 38 to 57% of patients with known sick sinus syndrome were unable to achieve a maximal heart rate of 120 beats per minute. This inadequate response
to exercise suggests chronotropic incompetence that occurs in persons with sick sinus syndrome, but there are no well-validated standards for diagnosing sick sinus syndrome with this.
exercise treadmill testing
It's been found that 38 to 57% of patients with known sick sinus syndrome were unable to achieve a maximal heart rate of 120 beats per minute. This inadequate response
to exercise suggests chronotropic incompetence that occurs in persons with sick sinus syndrome, but there are no well-validated standards for diagnosing sick sinus syndrome with this.
Carotid sinus massage or pressure When results in a sinoatrial pause for more than three seconds is also suggestive, but not diagnostic, of sick sinus syndrome. Carotid sinus massage or pressure
When results in a sinoatrial pause for more than three seconds is also suggestive, but not diagnostic, of sick sinus syndrome.

Investigations - Management

Fact Explanation
Electrocardiogram To look for the development of any other arrhythmias such as atrial fibrillation, atrial flutter or supraventricular tachyarrhythmias or atrioventricular block. Electrocardiogram
To look for the development of any other arrhythmias such as atrial fibrillation, atrial flutter or supraventricular tachyarrhythmias or atrioventricular block.
Echocardiography To assess ejection fraction for the development of possible congestive cardiac failure which can also be developed as a consequence of pacemaker implantation. This is thought to be due to the abnormal contraction pattern seen during ventricular (DDDR) pacing which may lead to left ventricular remodelling, decreased left ventricular function, and dilatation of the left atrium Echocardiography
To assess ejection fraction for the development of possible congestive cardiac failure which can also be developed as a consequence of pacemaker implantation. This is thought to be due to the abnormal contraction pattern seen during ventricular (DDDR) pacing which may lead to left ventricular remodelling, decreased left ventricular function, and dilatation of the left atrium
Clotting profile Patients with SSS are started on Warfarin to counteract thrombo-embolism, therefore monitoring with clotting profile should be done. Clotting profile
Patients with SSS are started on Warfarin to counteract thrombo-embolism, therefore monitoring with clotting profile should be done.
Echocardiography Congestive cardiac failure can be developed as a consequence of pacemaker implantation. This is thought to be due to the abnormal contraction pattern seen during ventricular (DDDR) pacing which may lead to left ventricular remodelling, decreased left ventricular function, and dilatation of the left atrium. To exclude heart failure before pacing, this is done Echocardiography
Congestive cardiac failure can be developed as a consequence of pacemaker implantation. This is thought to be due to the abnormal contraction pattern seen during ventricular (DDDR) pacing which may lead to left ventricular remodelling, decreased left ventricular function, and dilatation of the left atrium. To exclude heart failure before pacing, this is done
Electrocardiogram To demonstrate the possible variants of SSS such as sinus bradycardia, sinoatrial pause of three seconds or more, sinoatrial exit block, or sinus arrest, tachy-brady, syndrome, atrial fibrillation or flutter or atrioventricular block. Electrocardiogram
To demonstrate the possible variants of SSS such as sinus bradycardia, sinoatrial pause of three seconds or more, sinoatrial exit block, or sinus arrest, tachy-brady, syndrome, atrial fibrillation or flutter or atrioventricular block.

Management - Supportive

Fact Explanation
Patient education Patients need to be educated on the nature, course and prognosis of the disease, exercise, as well as special precautions to be done after pacemaker implantation Ex: They cannot undergo magnetic resonance imaging. Patient education
Patients need to be educated on the nature, course and prognosis of the disease, exercise, as well as special precautions to be done after pacemaker implantation Ex: They cannot undergo magnetic resonance imaging.
Patient identification A bracelet/ hand band or diagnosis card should be provided to identify patients in emergency situations such as during a syncope Patient identification
A bracelet/ hand band or diagnosis card should be provided to identify patients in emergency situations such as during a syncope
Treatment of congestive cardiac failure Treatment regime for heart failure including diuretics are needed if congestive cardiac failure develops. digitalis can be used if there's bradycardia associated with congestive cardiac failure but should be vigilant as it can worsen sinoatrial dysfunction Treatment of congestive cardiac failure
Treatment regime for heart failure including diuretics are needed if congestive cardiac failure develops. digitalis can be used if there's bradycardia associated with congestive cardiac failure but should be vigilant as it can worsen sinoatrial dysfunction
Anticoagulant therapy As these patients are at risk of thromboembolism due to atrial fibrillation, anticoagulation with Warfarin is needed Anticoagulant therapy
As these patients are at risk of thromboembolism due to atrial fibrillation, anticoagulation with Warfarin is needed
Diet There shouldn't be any dietary limitations except in heart failure where low salt diet is recommended. Diet
There shouldn't be any dietary limitations except in heart failure where low salt diet is recommended.
Exercise They should not do strenuous activities but shouldn't limit their normal day to day activities. Exercise
They should not do strenuous activities but shouldn't limit their normal day to day activities.

Management - Specific

Fact Explanation
No treatment If there's only bradycardia treatment may not be needed. No treatment
If there's only bradycardia treatment may not be needed.
permanent pacemaker implantation , , Implantation is indicated if documented symptomatic bradycardia with frequent sinus
pauses that produce symptoms,
Symptomatic chronotropic incompetence,
Symptomatic sinus bradycardia caused by medication required for medical condition.
Implantation is considered reasonable if significant symptoms of bradycardia and documented heart rate less than 40 beats per minute without documentation of
bradycardia during symptoms, syncope of unexplained origin with dysfunction of sinoatrial node discovered or provoked in electrophysiologic studies. Implantation may be considered minimally symptomatic patients with chronic heart rate less than
40 beats per minute while awake. with regard to the pacing mode in SSS, The results of 4 randomized studies were in favor of atrial or dual, rather than ventricular, in patients with SSS. They also showed that patients paced with atrial or dual mode had a significantly lower incidence of atrial fibrillation, stroke, and pacemaker syndrome than those paced with ventricular mode
permanent pacemaker implantation , ,
Implantation is indicated if documented symptomatic bradycardia with frequent sinus
pauses that produce symptoms,
Symptomatic chronotropic incompetence,
Symptomatic sinus bradycardia caused by medication required for medical condition.
Implantation is considered reasonable if significant symptoms of bradycardia and documented heart rate less than 40 beats per minute without documentation of
bradycardia during symptoms, syncope of unexplained origin with dysfunction of sinoatrial node discovered or provoked in electrophysiologic studies. Implantation may be considered minimally symptomatic patients with chronic heart rate less than
40 beats per minute while awake. with regard to the pacing mode in SSS, The results of 4 randomized studies were in favor of atrial or dual, rather than ventricular, in patients with SSS. They also showed that patients paced with atrial or dual mode had a significantly lower incidence of atrial fibrillation, stroke, and pacemaker syndrome than those paced with ventricular mode
Anti arrhythmic drug treatment Therapy for tachyarrhythmia with digitalis
and/or other antiarrhythmic agents may cause marked bradycardia and syncope therefore should be used with caution. Atropine, given for bradycardia, may promote
the appearance of tachyarrhythmia. Therefore drugs are used only with caution
Anti arrhythmic drug treatment
Therapy for tachyarrhythmia with digitalis
and/or other antiarrhythmic agents may cause marked bradycardia and syncope therefore should be used with caution. Atropine, given for bradycardia, may promote
the appearance of tachyarrhythmia. Therefore drugs are used only with caution
Catheter Ablation therapy Radiofrequency catheter ablation for atrial fibrillation in patients with SSS and a permanent pacemaker is found to be safe, but these patients have an increased risk of recurrence of atrial fibrillation Catheter Ablation therapy
Radiofrequency catheter ablation for atrial fibrillation in patients with SSS and a permanent pacemaker is found to be safe, but these patients have an increased risk of recurrence of atrial fibrillation

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