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Sick sinus syndrome, also known as sinus node dysfunction or sinus node disease, is a type of heart rhythm disorder. It affects the sinus node, the heart’s natural pacemaker that regulates heartbeat. Slow heartbeats, pauses (large intervals between heartbeats), or irregular heartbeats (arrhythmias) are symptoms of sick sinus syndrome.
The sick sinus condition is comparatively rare, but the risk of developing sick sinus syndrome increase with age. A pacemaker must eventually be installed to maintain the heart beating regularly in many people with sick sinus syndrome condition.
Symptoms
Sick sinus syndrome can occur without symptoms, and they can suddenly develop and resolve abruptly. Sick sinus syndrome symptoms and signs can include:
- feeling of fluttering or fast heartbeats (palpitations)
- fainting or feeling on the verge of fainting
- slower heartbeat (bradycardia)
- confusion
- chest pain or discomfort
- dizziness or lightheadedness
- exhaustion
- shortness of breath
If you experience any sick sinus syndrome signs or symptoms, consult your doctor. These issues can be brought on by a variety of medical diseases. It’s crucial to receive a prompt and precise diagnosis.
Call for emergency medical help immediately if you experience sudden or unexplained chest discomfort or believe you are suffering a heart attack.
Causes
The heart consists out of four chambers, two upper chambers called the atria and two lower chambers called the ventricles. The sinus node is located around the upper right chamber, or the atrium, acts as a natural pacemaker which controls the heart beats by sending electrical signals. When the atria receive these signals, the heart muscles start to contract and pump blood into the ventricles.
The heart signals will continue to go down to the atrioventricular (AV) node, where they slow down to allow blood to fill the ventricles. After that, the ventricles will contract to pump blood to the lungs or to rest of the body.
A healthy heart will have this process running smoothly, with a resting heart rate of 60-100 beats per minute.
Electrical signals are paced erratically in sick sinus syndrome. The heartbeat may be irregular, too rapid or too slow, or it may be interrupted by extended pauses. Although it is not very prevalent, the risk of acquiring sick sinus syndrome increases with age.
Sick sinus node syndrome can have various causes, such as:
- The deterioration of cardiac tissues with aging
- Sinus node damage or scarring following cardiac surgery
- Heart disease
- Inflammatory diseases that affect the heart
- Medications to manage high blood pressure, such as beta blockers and calcium channel blockers
- Medications to treat irregular heartbeats (arrhythmias)
- Some Alzheimer’s disease medications
- Having muscular dystrophy which is a neuromuscular disease
- Obstructive sleep apnea
- Uncommon genetic changes
Sick sinus syndrome has the following characteristics:
- Sinus bradycardia. A slow heartbeat that is produced by the sinus node.
- Sinus arrest. Beats are skipped as a result of a pause in sinus node’s signals.
- Sinoatrial exit block. Pauses or skipped beats result from slower or obstructed signals to the upper heart chambers.
- Chronotropic incompetence. At rest, the heart rate is within normal limits, but it doesn’t rise as high as it should with physical activity.
- Tachycardia-bradycardia syndrome. The heartbeats are spaced out widely and alternate between rhythms that are unusually slow and fast.
Risk factors
At any age, sick sinus syndrome can develop. Most people in their 70s or older seem to have it. Sick sinus syndrome development can be increased due to heart disease’s common risk factors. Heart disease risk factors include:
- Being overweight
- Not enough exercise
- High blood pressure
- Increased cholesterol
Diagnosis
The diagnosis of sick sinus syndrome starts from history taking about signs and symptoms, reviewing the medical history, physical examination, and further investigation can be confirmed by the following tests:
- Electrocardiogram (ECG or EKG). The heart’s electrical activity is assessed using this test. Legs and chest are equipped with sensors (electrodes). The sensors are connected to a computer by wires, which displays or prints the results. The rate of heartbeat can be determined via an ECG. In order to ascertain whether sick sinus syndrome is present, the doctor might examine signal patterns.
- Holter monitor. Wearing this portable ECG device throughout the day is possible for up to a day. For 24 to 72 hours, the heart’s activity is automatically recorded. A person who wears a monitor may additionally record their symptoms in a diary.
- Event recorder. This portable ECG device should be worn for up to 30 days, or until you have symptoms or an abnormal heartbeat. Typically, when symptoms appear, you have to press the button.
- Other monitors. Smart watches and other personal gadgets provide electrocardiogram monitoring. Find out if this is a possibility for you by speaking with your doctor.
- Implantable loop recorder. This tiny ECG device is inserted into the chest just beneath the skin. It is used to continuously and repeatedly monitor the electrical activity of the heart, especially in those who rarely sometimes experience symptoms.
- Electrophysiologic (EP) testing. An EP study test is scarcely used to determine sick sinus syndrome. It might be carried out, nonetheless, to examine the sinus node’s operation and the heart’s other electrical characteristics.
Thin, flexible wires with electrode tips are run into blood vessels to various locations within the heart during an EP examination. The electrodes can map the distribution of electrical signals throughout the heart once they are in place.
When the heart is beating irregularly, sick sinus syndrome symptoms such as lightheadedness, shortness of breath, and fainting, happen. On the day of the appointment, you might not be experiencing any symptoms.
Treatment
Treatment for sick sinuses syndrome aims to reduce or eliminate symptoms.
Among the possible treatments for sick sinus syndrome are:
- Routine checkups
- Medications
- Catheter procedures
- Implanting a device through surgery to keep the heartbeat regular (pacemaker)
Your doctor may normally advise routine checks to monitor your condition if you don’t have any symptoms. The majority of those with symptoms require surgery to install a device that keeps a normal heartbeat (pacemaker).
Medications
Some drugs, such as those prescribed for heart disease or high blood pressure, may impair sinus node function. Your doctor will probably review the medications you have already taken and may decide to change them or prescribe new ones. It may be necessary to use medications to stop or slow down rapid heartbeats.
If sick sinus syndrome is accompanied with atrial fibrillation or other abnormal heart rhythms linked to stroke, blood-thinners (anticoagulants) such as warfarin, dabigatran, or others may be administered.
Surgeries or other procedures
Most sick sinus syndrome patients eventually require a permanent device to regulate their heart rhythm (pacemaker). A pacemaker is a tiny, battery-operated device that is inserted through a small incision near the collarbone. To maintain the heart beating consistently, the pacemaker stimulates (paces) it as necessary.
The choice to implant a pacemaker if sick sinus syndrome symptoms are mild or uncommon will be depended on the ECG findings, your general health, and the possibility of more serious issues.
The kind of irregular heart rhythm you have will determine the type of pacemaker you require. Various pacemaker types include:
- Single chamber pacemaker. This kind often sends electrical impulses to the heart’s right lower chamber (ventricle).
- Dual chamber pacemaker. This type paces the right atrium separately from the right lower cardiac chamber (ventricle). Dual-chamber pacemakers are beneficial for the majority of patients with sick sinus syndrome.
- Biventricular pacemaker. Cardiovascular resynchronization treatment, commonly known as biventricular pacing, is used to treat patients with heart failure and irregular heartbeats. The right and left ventricles of the heart are stimulated by this kind of pacemaker to increase the heart’s efficiency.
After receiving a pacemaker, if your heart rate is still irregular, you may need medication, or a catheter-based surgery called cardiac ablation to regulate or control it. In order to block bad impulses and reestablish a regular heartbeat, cardiac ablation uses heat or cold energy to form microscopic scars inside the heart. Most frequently, catheters—thin, flexible tubes—that are put through veins or arteries are used. Ablation is occasionally carried out during cardiac surgery. Pacemaker users frequently undergo AV node ablation, a form of cardiac ablation, to manage their rapid heartbeats.
