Atrial fibrillation in the elderly
Introduction
Introduction to atrial fibrillation in the elderly Atrial fibrillation (AF) is one of the most common arrhythmias. It is the atrial rhythm of disordered and ineffective contraction of the atria. It is caused by a number of small reentry rings caused by atrial-dominant reentry rings. It is very common among the elderly. It is found in almost all organic heart disease and can occur in non-organic heart disease. The high incidence of atrial fibrillation, long duration, can also cause serious complications, such as heart failure and arterial embolism, resulting in increased disability or mortality, which seriously affects human health. basic knowledge The proportion of illness: 0.08% Susceptible people: the elderly Mode of infection: non-infectious Complications: angina pectoris heart failure
Cause
The cause of atrial fibrillation in the elderly
Rheumatic heart valve disease (30%):
Rheumatic valvular heart disease remains the most common cause of atrial fibrillation, especially in patients with mitral stenosis and regurgitation. Among patients with mitral stenosis, atrial fibrillation is 41%, and atrial fibrillation has a chance of atrial fibrillation. Smaller, the average age at which a patient has atrial fibrillation is about 37 years old, mostly female.
The mechanism of atrial fibrillation in rheumatic valvular heart disease is related to left atrial enlargement, elevated atrial pressure and atrial myopathy. Atrial enlargement, increased pressure and atrial fibrotic lesions cause the refractory period of the atrial muscles to be uneven. Inducing the occurrence of atrial fibrillation.
Coronary heart disease (20%):
With the increase in the incidence of coronary heart disease, coronary heart disease has become the leading cause of atrial fibrillation in many countries and regions. The proportion of the elderly is high, but atrial fibrillation is not a common clinical manifestation of coronary heart disease, in coronary angiography. Among patients with obvious coronary artery stenosis, atrial fibrillation accounted for 0.6% to 0.8%, and acute myocardial infarction, the incidence of atrial fibrillation accounted for 10% to 15%.
Cardiomyopathy (15%):
A variety of types of cardiomyopathy can occur in atrial fibrillation, the incidence rate is between 10% and 50%, more common in adults, children can also occur, mainly primary congestive cardiomyopathy, accounting for about 20%.
Hypertensive heart disease (15%):
The ratio of hypertension in the cause of atrial fibrillation is 9.3% to 22.6%. The occurrence of atrial fibrillation is related to hypertrophic myocardial electrophysiological abnormalities caused by hypertension, hypertrophic myocardial ischemia and hypertrophic myocardial fibrosis due to cardiac hypertrophy and fiber. Chemotherapy, ventricular compliance decreased, atrial pressure increased and left atrial enlargement, plus myocardial ischemia, which induced atrial electrophysiological disorders, leading to atrial fibrillation.
Constrictive pericarditis (10%):
The incidence of general patients is 22% to 36%, and the incidence of atrial fibrillation in elderly patients can reach 70%. Pericardial effusion can also be associated with atrial fibrillation.
Pulmonary heart disease (5%):
Atrial fibrillation in pulmonary heart disease has been reported to be 4% to 5%, often paroxysmal, which is related to repeated infections in the lungs, long-term hypoxia, acidosis and electrolyte imbalance.
7. Congenital heart disease In congenital heart disease, atrial fibrillation is mainly seen in atrial septal defect.
8. Sick sinus syndrome In 1967, Lown proposed the concept of sick sinus syndrome, including persistent sinus bradycardia, sinus arrest and sinus block and bradycardia-tachycardia. The tachycardia here includes atrial fibrillation. When the sinus bradycardia is slowed, the ectopic excitability of the atria is enhanced, and atrial fibrillation is prone to occur.
9. The main complication of pre-excitation syndrome pre-excitation syndrome is paroxysmal atrioventricular reentry tachycardia, followed by atrial fibrillation, the incidence of atrial fibrillation is about 12% to 18%, generally considered ventricular pre-excitation The incidence of atrial fibrillation is related to age, seldom occurs in children, and the incidence of atrial fibrillation is higher in elderly patients. The mechanism of ventricular pre-excitation of atrial fibrillation is currently unclear, and may be associated with pre-excitation caused by supraventricular tachycardia. Atrial electrophysiological instability, or ventricular premature contraction, retrograde atrial fibrillation through the atrioventricular bypass, atrial fibrillation caused by atrial vulnerability, and short-term bypass refractory period is also easy to induce atrial fibrillation .
10. Hyperthyroidism Atrial fibrillation is one of the main symptoms of hyperthyroidism. The incidence of atrial fibrillation in patients with hyperthyroidism is 15% to 20%. Elderly hyperthyroidism may have organic damage of the myocardium and prone to chronic atrial fibrillation.
Pathogenesis
Mechanism
(1) Theory of reentry mechanism: The mechanism of atrial fibrillation is complicated, and it is still being studied in depth. The earlier theory suggests that a single ectopic self-discipline in the atria emits impulses at a very fast frequency, so that the myocardial can not maintain synchronized activities. It causes tremors, but so far, both animal experiments and clinical electrophysiological results support the theory of reentry mechanisms. The evidence supporting the reentry mechanism is:
1 Atrial fibrillation is closely related to atrial flutter. Many strong evidences support the mechanism of atrial flutter as reentry. Clinically, atrial flutter and atrial fibrillation alternately appear. The essential difference between the two is that the atrial flutter remains at 1:1. Synergistic contraction; while atrial fibrillation, the atrium does not maintain a 1:1 synergistic contraction.
2 Atrial fibrillation is common in various clinical and experimental conditions of abnormal myocardial excitability, such as sick sinus syndrome, increased vagal excitability, atrial fibrosis or fat infiltration, animal experiments often use a method of stimulating the vagus nerve to induce atrial fibrillation.
3 program stimulation can induce clinical or experimental atrial fibrillation.
4 In many reentry models, ablation can terminate atrial fibrillation.
The computer model of 5 atrial fibrillation suggests a variety of reentry activities.
6 computerized mapping technology more often find the reentry excitatory mode in atrial fibrillation.
(2) Dominant ring theory: In 1962, Moe proposed multiple hypothesis of reentry wavelets. In 1979, Allessie not only confirmed this hypothesis, but also proposed the concept of the dominant ring, (Leading Circle) and the concept of wavelet wavelength based on the results of animal experiments. That is, the impulse is operated around a functional obstacle area (consisting of the myocardium in refractory period), and the impulses (child waves) emitted from the various parts of the main ring are transmitted to the center thereof and collide with each other there. A functional block zone (not a zone) is formed to prevent short-circuiting of the ring impulse, and the "dominant ring" refraction wave can be broken into a number of refractory-dependent small wavelets to form atrial fibrillation.
(3) Spin-wave reentry theory: The spin wave is an autonomously rotating wave, which is a kind of nonlinear wave. The newly discovered heart spin wave reentry provides a new explanation for the occurrence of atrial fibrillation. There is always no organization, irregular chaotic activities, but orderly. There is no anatomical or functional block in the center of spin wave reentry. On the contrary, the core is excitable myocardium, and the core is stable. Single type of rapid arrhythmia, such as ventricular tachycardia; and the unstable spin wave of the core position produces polymorphic tachyarrhythmia, such as atrial fibrillation, ventricular fibrillation, etc., unstable spin wave common core position and its core Changes in size and shape, accompanied by Doppler effect in the core, the myocardial excitation time of the core is short, and the swimming time of the myocardial region is prolonged. When the swimming core encounters myocardial scar tissue or blood vessels, Anchored into a stable spin wave, and under certain conditions, such as myocardial inhomogeneity, the core can swim again, so that the spin wave can be converted between stable and unstable, showing single and multi-type Conversion between arrhythmias Such as the mutual conversion of atrial flutter and atrial fibrillation.
2. Factors related to the occurrence of atrial fibrillation
(1) Atrial volume and lesions: the size of the atrial volume is related to the induction and persistence of atrial fibrillation, atrial load increase, atrial enlargement, acute and chronic injury, sinus node or internode bundle (myocardial) fibrosis and atrial fibrillation Related, atrial fibrillation is difficult to control when heart failure occurs.
(2) The wavelength of the excitation wave: the wavelength of the excitation wave is equal to the product of the conduction velocity of the excitation and the effective refractory period of the myocardium. Therefore, the slowing of the conduction and the shortening of the refractory period can shorten the wavelength of the excitation, and the wavelength of the excitation determines the atrial muscle. The number of wandering waves that can be generated within, the shorter the wavelength, the more wavelets are generated, which makes the arrhythmia more likely to occur and persist. In large experiments, it has been confirmed that drugs or stimulation can be used to prolong intra-atrial conduction or shorten refractory period. Atrial fibrillation can be induced.
(3) Myocardial heterogeneity and anisotropic structure: normal myocardium has structural and electrophysiological anisotropy (anis-otropy), structural anisotropy refers to different spatial arrangement of myocardial fibers, electrophysiological Anisotropy refers to the excitability in the myocardial fibers, the conduction velocity and the anisotropy of myocardial capacitance and electrical resistance. The atrial muscle fibers are slender and arranged in a longitudinal direction. The excitation is fast along the long diameter of the fiber, but the intensity of the agitation gradually decreases as the conduction distance increases. The transmission speed along the transverse path is slow, but the intensity is large (the transmission of the insurance factor is large). When the block is blocked in the long diameter direction, it can still slowly propagate from the transverse path. If the return path length can accept the excitation, the foldback can be formed. .
(4) Autonomic effects: The vagus nerve and sympathetic nerve play an important role in the onset of some atrial fibrillation, forming two different types of paroxysmal atrial fibrillation mediated by the vagus nerve and sympathetic nerve. The stability of myocardial electrical activity depends on the vagus nerve. And the balance of sympathetic activity, either of the two activities can cause arrhythmia.
(5) Age factor: With the increase of age, the sinus node is degenerative and prone to atrial fibrillation.
3. Pathophysiology The atrial functional tissue of chronic atrial fibrillation is replaced by fiber. The sinus node and the internode can be damaged. The sinus node can be blocked. After the atrial fibrillation, the left and right atrium will gradually expand. Half of the patients will There is an increase in pressure in the left atrium. If the sinus rhythm is restored, the pressure can be reduced and the atrium will be reduced. This is due to a decrease in cardiac compliance during atrial fibrillation and a shortened ventricular diastolic time, which leads to an increase in atrial pressure.
Atrial fibrillation has a great influence on hemodynamics. Atrial fibrillation only has extremely fast and irregular electrical activity, and loses the normal mechanical function of the atrium. During atrial fibrillation, the atrial reserve function and the active contraction dynamic function Loss, only retains its catheter function, the blood only passively sucks into the ventricle when the ventricle is dilated, the heart rate increases, the filling time is shortened, the cardiac output is reduced, and when the ventricular rate is 140 times/min, the cardiac output is significantly reduced, so that Blood pressure drops, inducing or aggravating heart failure.
Atrial fibrillation also affects cardiac function through rapid and irregular ventricular rate, and long-term effects can produce cardiomyopathy.
Atrial fibrillation can lead to thrombosis and embolism. Vincow proposed the vessel wall more than 150 years ago. The abnormalities of blood flow and blood components are the three elements of thrombosis. The atrial fibrillation has atrial contractile function loss, and the blood is in the atria. Slow flow rate, even stasis, is conducive to the formation of thrombosis, studies have confirmed that atrial fibrillation itself can lead to platelet activation, which promotes thrombosis, thrombus attached to the auricle, atrial, embolism can cause embolism, is the prognosis of elderly patients with atrial fibrillation The important complications have become one of the important factors affecting the prognosis of elderly patients with atrial fibrillation.
Prevention
Elderly atrial fibrillation prevention
The majority of atrial fibrillation and atrial flutter in the elderly occur in coronary heart disease, hypertensive heart disease, pulmonary heart disease, hypokalemia, acute lung infection or digitalis poisoning. Therefore, the cause should be first identified and the cause should be actively treated. Generally, before the onset of atrial fibrillation or atrial flutter, frequent frequent room early, should be actively treated to prevent the development of atrial fibrillation or atrial flutter. For repeated frequent authors, you can explore appropriate antiarrhythmic drugs for a long time with minimum dose. Maintain and prevent recurrence.
Complication
Elderly atrial fibrillation complications Complications, angina, heart failure
Persistent atrial fibrillation is prone to angina, heart failure, embolism and other complications.
Symptom
Symptoms of atrial fibrillation in the elderly Common symptoms Palpitation, fatigue, arrhythmia, fatigue, vertigo, apex, first heart sound, hyperthyroidism, hemoptysis, anterior heart area, distressed heart failure
Clinical manifestation
(1) Symptoms:
1 Symptoms: In addition to the hemodynamic changes caused by underlying heart disease, atrial fibrillation causes atrial contraction loss, ventricular contraction becomes irregular, and ventricular rate increases. The most common symptom of the patient is Palpitations, such as coronary heart disease, patients may have angina pectoris, dizziness, syncope, severe heart failure and shock, such as systolic rheumatic mitral stenosis, often induced acute pulmonary edema, accompanied by pulmonary hypertension can occur hemoptysis.
2 asymptomatic: some slow and moderate atrial fibrillation, patients can have no symptoms, especially in the elderly, often found in physical examination or ECG.
3 atypical symptoms: seen in slow or moderate-speed atrial fibrillation, the patient has no palpitations, may have fatigue, fatigue, pre-cardiac discomfort or slight pain, need to be further related to the diagnosis.
(2) Signs:
1 The signs of the original heart disease, the signs of atrial fibrillation vary with the original heart disease.
2 three signs of atrial fibrillation: the first heart sounds of the apex are different, the heart rhythm is absolutely uneven, and the pulse is short.
3 embolization sign: patients with atrial fibrillation can occur brain, lung and extremity vascular embolism sign, the incidence of embolism is related to age, atrial size and basic heart disease, the incidence of cerebral infarction in patients with atrial fibrillation is 5 times higher than the normal population, atrial fibrillation Loss of effective atrial contraction, slowing of blood flow in the atria, and even stasis, is conducive to the formation of thrombosis, thrombosis can cause various embolic complications, mitral stenosis is more likely to cause thrombosis, according to statistics, mitral valve In patients with stenotic atrial fibrillation, 40% of patients developed left atrial wall thrombosis; in mitral stenosis with sinus rhythm, only 2% had wall thrombosis.
2. Classification
(1) Classification according to the duration of atrial fibrillation:
1 Acute atrial fibrillation is atrial fibrillation that occurs within 24 to 48 hours.
2 chronic atrial fibrillation includes:
A. Paroxysmal atrial fibrillation: refers to the duration of the episode within one month, and lasts for several minutes to several days, and can be spontaneously terminated.
B. Persistent atrial fibrillation: The attack lasts for more than 1 month. Intervention is needed to restore sinus rhythm. There are many organic heart disease, and some paroxysmal atrial fibrillation can develop into persistent atrial fibrillation.
C. Persistent atrial fibrillation: refers to atrial fibrillation that cannot maintain sinus rhythm after conversion or conversion.
(2) According to ventricular rate classification, can be divided into slow-type atrial fibrillation: ventricular rate <60 times / min; moderate-speed atrial fibrillation: ventricular rate in 60 ~ 100 times / min; rapid atrial fibrillation: ventricular rate in 100 ~ 180 times / min; extremely rapid atrial fibrillation: ventricular rate 180 beats / min, the elderly or long-term patients are mostly slow and moderate atrial fibrillation, rapid and extremely rapid atrial fibrillation, Hemodynamics has a serious impact, easy to cause heart failure, myocardial ischemia and ventricular fibrillation, should control ventricular rhythm as soon as possible, the application of drugs or cardioversion.
(3) Classification according to the characteristics of seizures:
1 vagus nerve-mediated atrial fibrillation: increased vagal tone as an inducement, more common in patients without structural heart disease; seizures mainly at night, also seen in rest, drinking or after meals; ECG showed sinus bradycardia before seizure Stimulate the vagus nerve or apply stimulants to induce.
2 sympathetic-mediated atrial fibrillation: sympathetic excitation as the cause, more common in patients with structural heart disease, seizures mostly during the day, especially during strenuous exercise or emotional excitement, the electrocardiogram can show accelerated sinus rhythm before the onset, up to More than 90 times / min, exercise or application of sympathetic stimulants (such as isoproterenol) can often be induced.
Examine
Examination of atrial fibrillation in the elderly
Electrolyte disorders in the elderly (hyperkalemia, elevated blood calcium) can induce atrial fibrillation, abnormal serum T3, T4, atrial fibrillation can also occur.
The basic characteristics of atrial fibrillation on the electrocardiogram are: P waves disappear, replaced by f-waves of different sizes and amplitudes, with frequencies ranging from 350 to 600 beats/min, and the QRS waves are irregular and the rhythm is absolute. Mismatch, f wave is usually clear in II, III, aVF and V1 leads, other leads are often unclear, in which normal P wave disappears and tremor is the main diagnostic condition of atrial fibrillation, according to f wave in V1 lead The size can be divided into:
1 large large atrial fibrillation, that is, the f wave is greater than 1mm.
2 small atrial fibrillation: f wave is less than 1mm, the frequency of large and large atrial fibrillation is low, and the frequency of small atrial fibrillation is higher.
Diagnosis
Diagnosis and diagnosis of atrial fibrillation in the elderly
Diagnostic criteria
History
(1) Symptoms: The heart palpitations can be paroxysmal or persistent.
(2) Asymptomatic.
(3) The symptoms are not typical, or only chest tightness, fatigue.
2. The signs of the heart rhythm are absolutely uneven, the heart sounds are not strong and the pulse is short.
3. ECG
(1) The P wave disappears with the f wave with different amplitude, shape and rhythm; the frequency is 350-600 times/min, and the f wave can be quite obvious, similar to the impure atrial flutter; it can also be slender and difficult to identify.
(2) The RR spacing is absolutely irregular.
In the elderly, there are generally pathological and physiological conduction abnormalities, sometimes coexisting with other types of arrhythmia, such as pre-systolic, paroxysmal supraventricular or ventricular tachycardia, and various atrioventricular block, And the ECG performance is not typical.
Differential diagnosis
1. Atrial fibrillation combined with early and indoor differential conduction, clinically more common, should pay attention to identify and guide treatment.
2. Atrial fibrillation with rapid and wide deformity QRS waves are common in atrial fibrillation with bundle branch block, ventricular tachycardia, pre-excitation syndrome, etc., and their clinical significance varies greatly.
3. Atrial fibrillation and slow ventricular rate in the elderly often combined with atrioventricular conduction system dysfunction, so prone to slow ventricular rate.
About 70% of atrial fibrillation occurs in organic heart disease. The diagnostic criteria mainly depend on electrocardiogram, especially 24h dynamic electrocardiogram. For patients complaining of angina pectoris, attention should be paid to the occurrence of atrial fibrillation in the onset of angina pectoris. If the abnormality occurs, it is highly suggestive that the underlying disease is coronary heart disease. For newly occurring atrial fibrillation, 24h dynamic electrocardiogram should be recorded, serum T3, T4, and blood ions should be examined simultaneously, and echocardiographic examination of left atrial diameter and left ventricular function should be performed. And the presence or absence of intracardiac thrombosis is beneficial for diagnosing the cause and guiding treatment.
