Sick sinus syndrome

Introduction to sick sinus syndrome Sick sinus syndrome (SSS) is referred to as sick sinus syndrome or sick sinus. Sick sinus syndrome is due to the sinus node or surrounding tissues (including atrial, atrioventricular junction, etc.) Sexual lesions, arrhythmia caused by sinus node impulse formation disorder and impulsive efferent disorder, mainly sinus bradycardia, sinus conduction block, sinus arrest, or bradycardia-cardiac Overspeed syndrome. basic knowledge The proportion of illness: 0.04% Susceptible people: no specific population Mode of infection: non-infectious Complications: Insomnia Shock

Etiology of sick sinus syndrome

Drug induced (25%)

1 anti-arrhythmia drugs. Such as quinidine, procainamide, propiamine, propafenone, encarni, flecainide, etc. are membrane inhibitors, can inhibit the pacing autonomic sinus node, can also inhibit the atrioventricular junction The function of the secondary pacing point is that when the above drugs are used in patients with sick sinus syndrome, the sinus node function can be inhibited, the sinus node recovery time (SNRT) is prolonged and sinus arrest occurs, sinus Bradycardia. 2 Digitalis drugs: In most cases, digitalis can shorten the recovery time of sinoatrial node, and it can be prolonged. In most cases, medication is safe, and a small number of patients will aggravate the degree of sinus bradycardia. Heart rhythm changes should be closely observed when rehmannia. 3 antihypertensive drugs: such as lishepine, guanethidine, clonidine, etc. can slow heart rate. 4 other drugs: such as antidepressants: amitriptyline, chlorpromazine, cimetidine, lithium carbonate, etc., can also slow heart rate.

Sinus node fibrosis (20%)

Is the most common cause, except for the sinoatrial node and its adjacent tissues, the rest of the cardiac conduction system, such as the atrioventricular node, His bundle and bundle branch system, can also be involved, causing multiple potential pacing and conduction dysfunction Lead to the so-called total conduction system disease, with the gradual fibrosis of the sinoatrial node with age, the pacemaker cells are replaced by fibrous tissue, the normal function of the sinus node is gradually lost, and the ventricular pacing or conduction dysfunction is complicated. , also known as double-junction lesions; at the same time involving the left and right bundle branches called the full conduction system lesions.

Coronary heart disease (10%)

Coronary heart disease: mainly for vascular ischemia or sclerotherapy of sinus node, coronary heart disease is the most common cause of sick sinus syndrome, but foreign pathological anatomy reports that there are 2 / 3 sinus of patients with sick sinus syndrome The vessel blood vessels are normal. Some cases have sinus node arterial ischemia. The cause is thromboembolism caused by coronary heart disease. It can also cause sinus node ischemia caused by vascular wall lesions in some immune diseases. Both sick sinus syndrome and coronary heart disease coexist.

Cardiomyopathy (10%)

Cardiomyopathy is also more common in the etiology of sick sinus syndrome. According to foreign reports, the incidence rate is about 16.4%, according to the domestic reported incidence of 13.9%; acute myocardial infarction or ischemia. Acute heart inflammation, valvular and structural lesions can cause this disease; the incidence of myocarditis according to foreign reports is 5.3%, according to the domestic reported incidence of 4.0%, including viral, bacterial myocarditis, etc.; myocardial metabolism or invasive lesions: Myocardial amyloidosis, hemochromatosis, sarcoidosis, malignant tumors.

Other disease factors (15%)

Systemic immune diseases: such as rheumatic carditis, rheumatic heart disease (incidence rate 5.8% to 6.4%), systemic lupus erythematosus, etc.; congenital diseases: congenital heart disease, familial QT prolongation syndrome, familial Sick sinus syndrome, familial congenital sinus node dysplasia, Friedreich hereditary ataxia, progressive muscular atrophy, muscular dystrophy, etc.; Keshan disease, hypertensive heart disease, pericarditis, syphilis Sexual heart disease, mitral valve prolapse syndrome; hyperthyroidism, diabetic cardiomyopathy and mediastinal radiation therapy.

Surgical injury (15%)

Direct surgical injury, such as open heart surgery, myocardial catheterization can also damage the sinus node and surrounding tissues.

Pathogenesis:

The incidence of familial sick sinus syndrome is not high, only a minority of sick sinus syndrome, due to structural abnormalities of congenital sinus node. Due to the different etiology of pathological sinus syndrome, the location and extent of pathological damage are different, and the mechanism of occurrence is different, there are the following:

1. Effects on the self-discipline, conductivity and excitability of sinus node tissue cells.

2. The occurrence of sick sinus syndrome is related to the autophysiological characteristics of sinus node.

3. The occurrence of sick sinus syndrome is related to the blood supply of sinus node.

4. Sick sinus syndrome results in sinus blockage due to sinus node activation and dysfunction.

5. The vagus nerve is hyperactive.

6. Sick sinus syndrome is an adenosine-mediated disease.

1 Antiarrhythmic drugs are divided into four categories according to their effects:

Class I antiarrhythmic drugs: such as quinidine, procainamide, propiamine, propafenone, encarni, flecainide, etc. are membrane inhibitors that inhibit the pacing autonomy of the sinus node. It can also inhibit the function of secondary pacing point in the atrioventricular junction area. When the above drugs are used in patients with sick sinus syndrome, the sinus node function can be inhibited, and the sinus node recovery time (SNRT) is prolonged and sinus occurs. Sexual arrest, sinus bradycardia.

Class II antiarrhythmic drugs: such as -adrenergic blockers, can inhibit the self-discipline of patients with sick sinus syndrome, prolong the recovery time of sinus node, and sinus block.

Class III antiarrhythmic drugs: such as amiodarone, sotalol, can directly act on the sinus node cell membrane to inhibit its membrane potential, and can inhibit the activity of sympathetic nerves.

Class IV antiarrhythmic drugs: such as calcium ion antagonists: verapamil, diltiazem, nitrendine, application of blockade of Ca2 channel drugs, may inhibit the action potential spontaneous diastolic depolarization of sinus node cells, and Sinus bradycardia, sinus arrest, etc.

2 Digitalis drugs: In most cases, digitalis can shorten the recovery time of sinoatrial node, and it can be prolonged. In most cases, medication is safe, and a small number of patients will aggravate the degree of sinus bradycardia. Heart rhythm changes should be closely observed when rehmannia.

3 antihypertensive drugs: such as lishepine, guanethidine, clonidine, etc. can slow heart rate.

4 other drugs: such as antidepressants: amitriptyline, chlorpromazine, cimetidine, lithium carbonate, etc., can also slow heart rate.

(2) Acute myocardial infarction or ischemia.

(3) Acute heart inflammation, valvular and structural lesions.

(4) The vagus nerve tension caused by any cause is too high.

(5) electrolyte imbalance, hyperkalemia, hypercapnia, low temperature, etc.

(6) Other diseases: such as hyperthyroidism, lung disease, mucinous edema, intracranial hypertension, obstructive jaundice, cholelithiasis, cholecystitis, gram-negative bacilli sepsis, depression, eye surgery, etc.

Sick sinus syndrome prevention

Sick sinus syndrome is often caused by degenerative lesions or fibrosis of the sinoatrial node and its surrounding tissues. It should actively find the cause, symptomatic treatment, and prevent further development of the disease. If the heart rate is too slow, the artificial cardiac pacemaker can be placed. Maintain normal life and work.

1. Active treatment of primary disease: eliminate the basic causes, such as active treatment of myocarditis, acute myocardial infarction and myocardial ischemia, restore electrolyte balance; eliminate the cause of the disease, after the disease should adhere to the doctor's advice, consolidate the effect, avoid adverse stimulation .

2. Use or disable various drugs that inhibit sinus node function: such as -blockers, verapamil, digitalis, and other antiarrhythmic drugs.

3. The daily life is regular, the diet is appropriate, and exercise properly to prevent the invasion of external evils.

4. Acute sinus node dysfunction should be treated with active etiology, temporarily increase the sinus heart rate, so as not to evolve into chronic disease sinus syndrome; for the diagnosis of chronic sinus syndrome should be actively taken comprehensive treatment of traditional Chinese and Western medicine to improve the sinus If the function of the ablation is to block the further development of the disease, if the drug treatment is poor or the clinical symptoms are obvious, the pacemaker should be installed early to prevent sudden death.

Complications of sick sinus syndrome Complications, insomnia, shock

1. Dizziness: When the sinus bradycardia is more serious, the patient may have symptoms such as dizziness, personality change, memory loss, weakness, and insomnia.

2. Syncope: According to statistics, the incidence of syncope is 41% to 69%. Atrial arrest caused by tachycardia is the most common cause. Severe sinus bradycardia is a rare cause.

3. A-S Syndrome: The prevalence of typical A-S syndrome in sick sinus syndrome is 6.7% to 13.3%. It is a clinical synthesis of syncope or convulsions due to acute cardiogenic cerebral ischemia. The levy is dangerous and often a precursor to sudden death.

In addition, the low cardiac output seriously affects the kidney and other organs can also cause oliguria, dyspepsia, slow and rapid syndrome may also lead to vascular embolism symptoms, occasionally angina, heart failure or shock and other serious complications, and even lead to The patient died.

Symptoms of sick sinus syndrome Syndrome Common symptoms Memory disorder or emotional excitement... Bradycardia with palpitations, fatigue, pale arrhythmia, tachycardia, chest pain, chest tightness, palpitations, chest tightness, insomnia, and excitement

Insidious onset, slow progress, sometimes accidentally discovered. Such as heart, brain, gastrointestinal and kidney, such as lack of blood supply, such as fatigue, chest pain, palpitations, dizziness, insomnia, memory loss, irritability, slow response, excessive urine, poor appetite. May last or intermittently. When there is a high degree of sinus block or sinus arrest, a short burst of syncope or sputum may occur. Occasionally, angina, heart failure or shock can occur. Acute inferior myocardial infarction and myocarditis can cause temporary sinus node dysfunction, and the acute phase disappears after the past. Clinical manifestations vary in severity and can be intermittent. Most of the brain, heart, kidney and other organs due to slow heart rate, especially cerebral blood supply symptoms. Light fatigue, dizziness, vertigo, insomnia, poor memory, unresponsiveness or irritability are easily misdiagnosed as neurosis, and the elderly are also easily misdiagnosed as cerebrovascular accidents or aging syndrome.

Examination of sick sinus syndrome

First, the electrocardiogram

(1) Significant and persistent sinus bradycardia: heart rate is slower than 45 beats per minute, or accompanied by symptoms such as dizziness, darkness, approximate syncope or syncope, and exclude certain drugs, vagus nerve or metabolic disorders, etc. Caused by, should be highly suspected of sick sinus syndrome, significant sinus bradycardia can often be accompanied by a degree of atrioventricular block, may also be associated with sinus arrest, ventricular escape or escape rhythm .

(2) sinus conduction block: severe sinus bradycardia, often accompanied by sinus conduction block, sinus block can occur alone, including coronary heart disease and atrial lesions, may be sinus conduction Blockade is more common, once sinus conduction block has a certain difficulty in the diagnosis of surface electrocardiogram, but second degree I sinus block is one of the most common electrocardiogram manifestations of sick sinus syndrome, three Sinus atrial block is difficult to identify with sinus arrest on the electrocardiogram.

Sinus conduction block can be sporadic or frequent, with more nighttime episodes than during the day, and high sinus conduction block with standing or sitting position without escape rhythm can occur.

(3) sinus arrest: short sinus arrest can be no obvious symptoms, sinus arrest more than 8s, if not accompanied by escape or escape rhythm, prone to syncope or A-S syndrome, lasting Patients with sexual or permanent sinus arrest have a sustained escape rhythm on the electrocardiogram, which may be accelerated or slow escape rhythm.

The long PP interval after sinus arrest is not a multiple of the PP interval between basic sinus rhythm and is the main distinguishing point from second-degree sinus conduction block.

(4) bradycardia-tachycardia syndrome (referred to as slow-fast syndrome): bradycardia tachycardia syndrome is a common type of sick sinus syndrome, which is serious One of the common manifestations of sick sinus syndrome, the main manifestation of slow-fast syndrome on the electrocardiogram is the occurrence of tachyarrhythmia on the basis of bradycardia. The bradycardia mainly includes significant sinus bradycardia, sinus Atrial block and sinus arrest, but sinus bradycardia is the most common, with tachyarrhythmia mainly including atrial tachycardia, atrial fibrillation, supraventricular tachycardia, atrioventricular junctional cardiac motility Overspeed, but generally considered atrial fibrillation is the most common form of tachycardia, mostly paroxysmal, atrial tachycardia, atrioventricular junction tachycardia is not common, tachyarrhythmia ventricular tachycardia Overspeed is less common, only about 3%, and there are reports of 8% to 10%. The rapid arrhythmia and sinus bradycardia change each other to form a slow-fast syndrome, in the case of slow-fast arrhythmia , often seen sinus arrest (usually 2s) Without accompanying escape, it is often seen from the 24h dynamic electrocardiogram that sinus arrest occurs after termination of atrial fibrillation, and causes insufficient blood supply to the brain, causing dizziness, syncope, A-S syndrome, and slow-fast syndrome. Later, it can be gradually converted to ectopic heart rhythm, mostly atrial fibrillation. Therefore, patients with atrial fibrillation should consider the possibility of diseased sinus syndrome when the condition is unclear. At this time, using digitalis or cardioversion will cause Severe bradycardia should be closely monitored.

(5) Double knot lesions and conduction block: When the lesion affects the sinus node and the atrioventricular junction, two mixed arrhythmias may occur, such as sinus bradycardia with atrioventricular block, sinus block. Combined atrioventricular block, atrial flutter or atrial fibrillation with atrioventricular block, severe sinus bradycardia, sinus block, sinus arrest without atrioventricular transfer or escape rhythm At this time, this is a double knot lesion, and about 30% of patients with sick sinus syndrome have double knot lesions.

In patients with sick sinus syndrome and atrioventricular block, most of the block is on the His bundle, and some patients can be combined with His bundle block.

The incidence of sick sinus syndrome combined with indoor conduction block is high.

(6) Intermittent abnormal prolongation of atrial contraction before contraction: Most of the compensatory interval after atrial contraction is incomplete compensatory interval, and atrial premature contraction occurs in late diastole due to the sinus The agonistic physiological disturbance occurs, and the recovery cycle can form a complete compensatory interval. If the pre-atrial contraction occurs in the early stage of diastole and is an abnormal extension of the compensatory interval, the prolongation or presence of the sinus node refractory period should be suspected. Once sinus conduction block.

(7) Long intermittent after termination of supraventricular tachycardia: some patients have long pauses when supraventricular tachycardia (including atrial flutter, atrial fibrillation) is terminated, especially for long interval >2s, even if The various manifestations of disease-free sinus syndrome on the ECG should also be suspected of having a sick sinus syndrome.

(8) The mixed manifestations of electrocardiogram leading to sick sinus syndrome: sick sinus syndrome due to different degrees of sinus node lesions and whether it combined with other parts of the lesion, leading to ECG performance of patients with sick sinus syndrome Different from each other, it can be expressed as a single abnormality or coexistence of multiple abnormal electrocardiograms, which makes the performance of the electrocardiogram more complicated. Therefore, it should be carefully identified and electrophysiological examination should be performed if necessary.

The incidence of main manifestations of electrocardiogram in sick sinus syndrome:

1 over-arrhythmia: the incidence rate is 35%, can show significant and long-lasting sinus bradycardia, it is the most common type of bradyarrhythmia; followed by sinus arrest, sinus conduction Blocking and escape rhythm in the atrioventricular junction and recovery of sinus rhythm after cardioversion.

2 bradycardia - tachycardia (slow-fast) syndrome: the incidence rate is 33%.

3 sinus node-atrioventricular nodular lesion syndrome (also known as double knot lesion): the incidence rate is 25%.

4 total conduction system defects: the incidence rate of 5%, patients with sick sinus syndrome, in addition to sinus node itself stimulating and / or conduction disorders, about half of the cases have atrioventricular block, other appear as in the room, Conduction barriers in indoor conduction systems.

Second, the determination of sinus node function: The following methods can be applied to suspected patients.

(1) Atropine test: intravenous atropine 1.5-2mg, 1, 2, 3, 5, 10, 15, 20 minutes after injection, respectively, continuous electrocardiogram or oscilloscope observation, such as sinus rhythm can not be increased to 90 times / min And (or) sinus block, borderline rhythm, supraventricular tachycardia is positive, such as sinus rhythm increase > 90 times / negative, mostly vagal hyperfunction, glaucoma or obvious prostatic hypertrophy The patient is used with caution.

(B) sinus node function by transesophageal or direct atrial pacing: This method is a reliable method for the diagnosis of sick sinus syndrome, especially combined with drug blockade of the autonomic nervous system, can improve sensitivity, transesophageal insertion Bipolar pacing catheter, the electrode is placed behind the left atrium, then connected to the artificial cardiac pacemaker, rapid pacing, frequency from 90 times per minute, 100 times, 120 times, gradually increased to 150 times per minute, each time Stroke for 1 minute, then stop pacing, and trace the electrocardiogram, see how long the sinus node can wake up and re-jump, the time from stopping stimulation pacing to restoring sinus P wave is the recovery time of sinus node, disease The intrinsic heart rate of sinus syndrome was below 80 beats/min (measured after atropine 2mg plus propranolol 5mg intravenous injection), sinus node recovery time >1500m.s, sinus conduction time >180m.s.

(C) dynamic ECG monitoring: can understand the fastest and slowest heart rate, sinus arrest, sinus block and other arrhythmia performance.

(4) Exercise test: When the treadmill or treadmill exercise test, the heart rate can not be significantly increased after exercise, suggesting that the sinus node is dysfunctional, but it must be closely monitored to prevent accidents.

In addition, for a small number of patients with sick sinus syndrome who are still undiagnosed, if electrophysiological examination can be used, it should be determined:

(1) Sinus node recovery time (SNRT, CSNRT): 1500ms.

(2) Sinus conduction time (SACT): >120ms is abnormal, >160ms has diagnostic significance.

(3) Intrinsic heart rate (IHR) of sinus node.

(4) Sinus node electrogram (SNE) and sinus node refractory period (SNERP).

The abnormal rate of SNRT in the clearly diagnosed sick sinus syndrome is 35% to 100%, and the abnormal rate of SACT is 15% to 75%. If the two are combined to evaluate the sinus node function, the sensitivity is 70%. The sexuality is 90%. If SNERP and SNE are added to evaluate the sinus node function, the diagnostic sensitivity can be further improved. The electrophysiological examination can be used to evaluate the sinus node function: 1 to determine whether there is any change in sinus node function; To determine whether the nature of sinus node dysfunction is reversible or irreversible, to understand the relationship between the occurrence of symptoms and the occurrence of arrhythmia; 3 to determine the extent of sinus node lesions, to determine whether a permanent pacemaker needs to be placed.

[ECG Features]

An electrocardiogram including sinus node dysfunction itself and an escape and/or escape rhythm secondary to dysfunction of the sinus node can also be associated with a short burst of tachyarrhythmia and/or an electrocardiogram of other parts of the conduction system. , 1 sinus conduction block and / or sinus rest and / or significant sinus bradycardia; 2 escape, short or continuous escape rhythm, escape the second law, travel rhythm, sinus Sexual arrest is characterized by the disappearance of P waves, resulting in a long sinus PP interval, which is not a multiple of the basic sinus rhythm PP interval, in addition, if continuous electrocardiogram or dynamic electrocardiogram is used, The long PP interval caused by multiple sinus arrests is not equal to each other, and there is no greatest common denominator; 3 accompanied by atrial arrhythmia, such as frequent premature beats, burst or recurrent short-term atrial Quiver, atrial flutter or atrial tachycardia, and slow sinus rhythm form the so-called bradycardia-tachycardia syndrome, after rapid arrhythmia automatically stops, sinus rhythm often lasts for more than 2 seconds Appear after an interval; pacing and/or transmission at the junction of 4 chambers Guiding dysfunction, manifested as delay in the atrioventricular junction escape, slow escape at the atrioventricular junction escape rhythm (easy stroke period > 1.5s) or atrioventricular block, and occasionally combined bundle branch block.

The first (II) (aVF) shows the second simulation of the room flutter V5 (a) shows that the cardiac pause after the atrial fibrillation is stopped for 3.96 seconds. The third simulation V5 (b) shows the short-term supraventricular tachycardia after the suspension The heart pauses and a ventricular escape follows.

Dynamic electrocardiogram (DCG) performance was divided into 4 types: type I, severe and persistent sinus bradycardia (21.1%); type II, sinus sinus with sinus arrest or sinus block (30.5%); type III, Slow-fast syndrome (12.6%); type IV, double-junction lesions (35.8%), in which the incidence of syncope or erythema in double-dose lesions (70.6%) was significantly higher than other types, clinical manifestations of syncope or black-spotted DCG The mean interval was 4.9 ± 0.7 seconds, significantly longer than asymptomatic. The average follow-up of those who did not use pacing was 9 and a half years, showing a fairly long natural history. No deaths from this syndrome during follow-up, but Sutton et al observed that The annual survival rate is 85% to 92%, and 52% in 7 years.

Diagnosis and diagnosis of sick sinus syndrome

The clinical manifestations of this disease vary in severity, and may be intermittent, mostly due to slow heart rate, brain, heart, kidney and other organs. Insufficient blood supply, especially cerebral blood supply symptoms, light fatigue, dizziness, vertigo, insomnia Poor memory, unresponsiveness or irritability, etc., severe cases can cause transient darkness, near syncope, syncope or Assy syndrome, some patients with short-chamber supraventricular tachyarrhythmia, also known as slow-fast syndrome When a rapid arrhythmia episode occurs, the heart rate can suddenly accelerate up to 100 times/min or more, and the duration is different. After the sudden suspension of tachycardia, there may be a cardiac arrest with or without syncope episodes, severe bradycardia or tachycardia. Causes heart palpitations, can also aggravate the original heart disease symptoms, causing heart failure or angina.

1. Sick sinus syndrome and drug-induced sinus bradycardia, sinus arrest, sinus conduction block and other three abnormalities after the drug is discontinued, sinus arrhythmia can disappear quickly; Difficulty in the treatment of sick sinus syndrome.

2. Bradycardia in sinus syndrome - tachycardia syndrome should be differentiated from variability fast-slow syndrome. Washington first proposed a tachycardia caused by atrial premature contraction. The combination of slow and short-term atrial fibrillation or atrial flutter appears as a fast-slow syndrome on the electrocardiogram.

3. Neurosis: Reduce vagal tone, sinus arrhythmia can disappear quickly.

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