Arrhythmia Sick Sinus Syndrome

• The sick sinus syndrome is a presentation with dizziness, confusion, fatigue, syncope, and heart failure caused by SA node dysfunction.

Several electrocardiographical abnormalities caused by a malfunction of the sinoatrial node of the heart, in which there are episodes of tachycardia alternating with episodes of heart block or severely decreased heart rate, often with loss of consciousness

• It is manifested by sinus bradycardia, sinoatrial block, sinus arrest, bradycardia – tachycardia syndrome, atrial fibrillation, atrial flutter, atrial tachycardias.
• Failure of sinus impulse formation is called sinus arrest.
• Sick sinus syndrome (SSS) is characterized by chronic sinoatrial (SA) nodal dysfunction, a sluggish or absent SA nodal pacemaker after DC cardioversion, and/or frequently depressed escape pacemakers
• When sinus arrest occurs there is no impulse formation by the sinus node but the junction or the ventricle take
• If, after the sinus arrest there are only 1 or 2 beats formed by the junction or ventricle they are called junctional
• or ventricular escape beats. After a few escape beats sinus rhythm may be restored.
• If there is impulse formation but there is block of conduction of sinus impulses to the surrounding atrial tissue it is called sinus exit block.
• over and start generating impulse.
• This is seen as absence of PQRST sequence in ECG followed by junctional or ventricular rhythm.
• ‘This new rhythm by the junction or ventricle is called junctional escape rhythm or ventricular escape rhythm.
• The junctional escape rhythm has no preceding P and has narrow QRS complexes.
• The ventricular escape rhythm has no preceding P and has QRS complexes.
• It is seen as a pause or a missing of complete PQRST sequence in ECG.

Treatment of the sick sinus syndrome

• Treatment of SSS is directed at symptoms.
• These include presyncope, syncope,lightheadedness,  and, less often, dyspnea on exertion or worsening angina.
• along with that, patients with tachy-brady syndrome may present with palpitations and other symptoms associated with a rapid heart rate.
• Treatment of SSS should begin with a search for remediable causes of sinoatrial (SA) nodal depression, such as drugs (eg, beta blockers, digoxin, sympathetic blockers, lithium,calcium channel blockers,  cimetidine, and antiarrhythmic agents), ischemia, and autonomic imbalance.
• Symptomatic SSS is usually treated with a pacemaker, and SSS accounts for over one-half of pacemakers implanted

First degree sino atrial exit block

• This cannot be recognized on ECG.

Second degree SA block –

• There are intermittently absent P waves.

Third degree or complete SA block –

• There is no atrial activity and another pacekmaker takes over.
• Sinus pauses of more than three seconds are abnormal.
• Sinus pauses of more than five seconds require a pacemaker.
• Maneuvers which slow the sinus rate are carotid sinus massage and Valsalva maneuver.

Treatment of sinus node disease

• Atropine – 0.5 to 2 mg IV.
• Isoproterenol – 1 mg IV to be repeated.
• Drug therapy is not of use in sinus node disease and pacemaker implantation is the only treatment. A dual chamber pacemaker is the best option.