Pacemaker syndrome

Introduction to pacemaker syndrome Pacemaker syndrome is a group of clinical syndromes caused by hemodynamic and electrophysiological abnormalities after pacemaker implantation. Mainly due to a series of symptoms and signs caused by low cardiac output, but different individuals have different performances due to different cardiac function compensatory ability. Generally speaking, the elderly are more common. basic knowledge Probability ratio: The incidence of pacemaker wear is about 3%-8% Susceptible people: no specific population Mode of infection: non-infectious Complications: syncope congestive heart failure hypotension

Causes of pacemaker syndrome

(1) Causes of the disease

The cause of the disease is multifactorial:

1 case of synchronous contraction loss, can reduce cardiac output by 20% to 30%, such as the original cardiac dysfunction can be reduced by more than 50%;

2 atrioventricular valve insufficiency caused systolic blood reflux back to the atria, increasing atrial load;

3 increased atrial pressure, inhibiting the normal contraction and reflex of peripheral blood vessels, leading to a drop in blood pressure;

4 right ventricular pacing causes the biventricular systole to be out of sync;

5 ventricles, retrograde conduction of the atrial electrical activity room.

(two) pathogenesis

Pacemaker syndrome was first reported by Mitsui et al. in 1960. In 1974, Hoss and Strait studied hemodynamics and morphological changes. Since then, the mechanism and pathophysiological changes of pacemaker syndrome have been studied. With a deeper understanding, the cause of the disease, the cause is clear, but its pathogenesis is the direct impact of ventricular pacing and the impact of abnormal electrophysiological phenomena.

1. Direct impact of ventricular pacing

(1) Asynchronous contraction of the atrioventricular: As early as the 17th century, British physiologist Harvey had discovered that atrial contraction plays an important role in blood circulation. Modern cardiology has proved that atrial contraction can accelerate ventricular filling and atrioventricular valve. Closed, this effect is called the Booster pump mechanism. Some people have used ventricular plethysmography to show that in the ventricular filling, the atrial contraction can reach 15% to 30%, especially in the case of cardiac insufficiency. Due to the low compensatory function of ventricular filling, it is necessary to rely more on the contraction of the atria to maintain proper cardiac output. When the artificial cardiac pacemaker is implanted for ventricular pacing, the atrial boosting mechanism disappears, and the cardiac output can be output. The amount is significantly reduced, and some studies have shown that the sinus rhythm is reduced by 10% to 35%.

(2) mitral and tricuspid regurgitation: under ventricular pacing, due to the sequential disappearance of atrioventricular contraction, different degrees of mitral and tricuspid regurgitation can occur, even if the reverse flow is not large, It can be one of the triggering factors of pacemaker syndrome under the influence of other factors such as unsynchronized contraction of the atrioventricular.

(3) abnormal ventricular activation process: abnormal ventricular depolarization can cause contraction weakness, right ventricular pacing is the left ventricular branch block ventricular activation process, which can cause hemodynamic obstacles.

(4) Abnormal vascular reflex: After ventricular pacing, because the atrioventricular contraction is not synchronized, the atrium expands, the pressure rises, and then the reflex peripheral vascular resistance decreases, resulting in a decrease in blood pressure, and an increase in atrial natriuretic peptide level 7 ~ 8 times.

2. Effects of electrophysiological abnormalities

(1) Retrograde conduction of the chamber: As early as the early 1960s, artificial cardiac pacing has found that ventricular pacing can cause retrograde conduction in the room. Subsequently, many scholars have carried out this electrophysiological phenomenon. The study found that more than 60% of patients with sinus sinus syndrome had retrograde conduction in the ventricular pacing, and 40% of patients with complete atrioventricular block ventricular pacing Maintaining a 1:1 retrograde conduction of the chamber, patients with retrograde conduction of the ventricle, the atrium does not accelerate the filling of the ventricle at the end of diastole, but regularly discharges blood flow to the pulmonary and vena cava system when the atrioventricular valve is closed. , which causes a significant increase in the right atrial and pulmonary capillary wedge compression, and therefore, can cause severe hemodynamic disorders. Our study of 14 patients with pacemaker syndrome showed that the pulmonary capillary wedge pressure can rise to 3.3 ~ 4.0 kPa (25 ~ 30mmHg), with obvious low cardiac output and clinical appearance of syncope.

Studies have shown that hemodynamic disturbances caused by retrograde conduction of ventricular ventricular pacing are far more serious than atrial fibrillation and atrioventricular septum, and are one of the important causes of pacemaker syndrome.

(2) arrhythmia: after ventricular pacing can cause a variety of arrhythmia, such as ventricular premature contraction, repeated heart rhythm or reentry arrhythmia, etc., these arrhythmia frequent, continuous occurrence can also cause hemodynamic disturbance It also leads to a temporary or sustained decrease in cardiac output and is therefore one of the principles of pacemaker syndrome.

Pacemaker syndrome prevention

The pacemaker implanted before 1985 was not selective because of its pacing mode, so the incidence of pacemaker syndrome was high, 4.6%. The pacemaker implanted in the past 10 years mostly used physiological pacing. The incidence has dropped to 2.5%, and pacemaker syndrome is preventable. Before placement of a permanent right ventricular pacemaker, simple electrophysiological and hemodynamic tests are performed to find the optimal pacing frequency. And pacing mode; avoid permanent pacing in patients with retrograde ventricular pacing during temporary pacing, especially in patients with sick sinus syndrome; try to use physiological pacing for patients undergoing VVI pacing If the blood pressure is lowered by more than 20mmHg after implantation, it indicates that the pacemaker syndrome is likely to occur, and a double-chamber pacemaker should be implanted. However, the dual-chamber pacemaker is significantly delayed in the left atrium, and the AV interval is programmed. In the case of too long, the possibility of pacemaker syndrome does not rule out.

Pacemaker syndrome complications Complications, syncope, congestive heart failure, hypotension

1. Repeated syncope due to the loss of synchronous contraction of the atrioventricular, the cardiac output decreased by 20% to 30%, such as the patient's original cardiac dysfunction, the cardiac output can be reduced by more than 50%.

2. Congestive heart failure After the ventricular implantation of the pacemaker, the synchronous contraction of the atrioventricular is lost, the atrial pressure rises, the load increases, the cardiac output decreases, and the performance of congestive heart failure occurs.

3. After the hypotension is implanted into the ventricular pacemaker, the atrial dilatation, the pressure rises, and the reflex peripheral vascular resistance decreases, resulting in a decrease in blood pressure.

Pacemaker Syndrome Symptoms Common Symptoms Block Respiratory Dyslexia Hypotension Jugular Venous Aging Pulmonary Congestion

General pacemaker syndrome is caused by VVI pacing, but can also occur in AAI (suppressed on-demand atrial pacing) or frequency-adapted atrial pacing (AAIR).

Symptom

(1) Dizziness: About 92% of patients with pacemaker syndrome may have dizziness, of which 60% are persistent and the rest are intermittent.

(2) vertigo: about 85% of patients may have seizures.

(3) Syncope: About 49% of patients may have syncope, and 38% have syncope.

(4) shortness of breath: difficulty breathing, palpitations, lethargy, chest pain.

2. Signs

(1) Hypotension: Hypotension is one of the important signs of pacemaker syndrome, accounting for about 25% of the incidence, some patients with orthostatic hypotension, and some with blood pressure fluctuations.

(2) Signs of congestive heart failure: About 30% of patients with pacemaker syndrome may present with signs of congestive heart failure, such as lung vocalization, edema, and jugular vein engorgement.

(3) Heart sound changes and heart murmurs: There may be heart sounds ranging from strong to weak, heart rhythm irregularities, and heart murmurs during pacing.

(4) Liver pulsation.

General pacemaker syndrome is caused by VVI pacing, but can also occur in AAI (suppressed on-demand atrial pacing) or frequency-adapted atrial pacing (AAIR), which is mainly characterized by increased pacing frequency after activity. Symptoms such as palpitations, dizziness and other low cardiac output, the main reason is the dysfunction of the atrioventricular node, the atrioventricular block during AAIR pacing, the ventricular rate is too slow, and the cardiac output is insufficient.

Pacemaker syndrome check

Examination of electrophysiological indicators and hemodynamic indicators:

1. Electrophysiological indicators

After ventricular pacing, the room is retrogradely transmitted and symptoms appear, and the symptoms disappear after stopping pacing or changing the pace of the room.

2. Hemodynamic indicators

At the time of ventricular pacing, the arterial pressure decreased by 2.67 kPa (20-30 mmHg), and the pulmonary capillary wedge pressure and right atrial pressure increased significantly more than 2.67 kPa (20 mmHg), and symptoms appeared at the same time.

Diagnosis and diagnosis of pacemaker syndrome

diagnosis

The main premise for the diagnosis of cardiac pacemaker syndrome is that the patient develops symptoms after placement of the VVI artificial cardiac pacemaker; the pacemaker function is normal; hemodynamic abnormalities such as blood pressure and stroke volume occur during cardiac pacing Decreased, venous pressure, lung blunt pressure increased; symptoms disappeared or disappeared when the heart rhythm appeared.

Differential diagnosis

It is necessary to rule out neurological diseases and patients who are uncomfortable and intolerant in the short-term pacing treatment. For patients with normal pacing function and recurrent syncope or congestive heart failure, further intracardiac electrophysiological examination should be performed. And hemodynamic examinations, such as ventricular pacing with retrograde conduction and symptoms of the room, and the symptoms are significantly improved or disappeared after atrial pacing or atrioventricular sequential pacing; or arterial blood pressure drops during ventricular pacing >20 ~30mmHg (2.67 ~ 4.0kPa) and right atrial pressure increased >20mmHg (2.67kPa), and those with symptoms should be diagnosed as pacemaker syndrome.

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