2 English reference sinus atrial block
Sinus heart block
Overview of sinoatrial node block. It is a tissue lesion around sinoatrial node, which can prolong or fail to transmit excitement from sinoatrial node to atrium, leading to atrial ventricular arrest. Because it is efferent block or cannot be transmitted after excitement, it belongs to efferent block.
It may be caused by the weak impulse produced by sinoatrial node or the low stress of atrial tissue around it. It is found in diseases such as increased vagal tension, coronary heart disease, cardiomyopathy, myocarditis and its sequelae, acute myocardial infarction, etc. Can also be seen in digitalis, quinidine and other drug poisoning. A few have a family history.
Sinus atrial block is mostly asymptomatic, and when the heart rate slows down obviously, it can cause fatigue, dizziness, chest tightness and so on. Severe cases can cause cardiogenic syncope. Mild patients do not need treatment. Stubborn and persistent, accompanied by syncope or cardiogenic syncope, the author needs an artificial pacemaker. Clinically, it is divided into 3 degrees according to the degree of block: first degree sinus atrial block; Second degree sinus atrial block; High sinus node block and third degree sinus node block.
4 disease name sinus atrial block
5 English name sinus node block
6 sinus atrial block, alias sinus atrial block
7 classification cardiovascular medicine > arrhythmia > sinus arrhythmia
8 ICD number I45.8
9 Epidemiology 1964 Greenwood and others reviewed more than 200 cases of sinus node block, and found that 2/3 patients had evidence of heart disease or drug poisoning, mainly myocardial ischemia or rheumatic fever, but 1/3 patients had no inducement and were often young people.
10 etiology 1. More common in patients with organic heart disease? Coronary heart disease is the most common cause, accounting for about 40%. The organic damage around sinoatrial node is caused by myocardial ischemia. In acute inferior posterior myocardial infarction, the incidence of sinus block is 3.5%, which is far less than sinus bradycardia. The reason may be the increase of vagus nerve tension, and sinus node ischemia or infarction is also common. In addition, it can also be seen in hypertensive heart disease, rheumatic heart disease, cardiomyopathy, congenital heart disease, sinus node and its surrounding tissue lesions caused by chronic inflammation or ischemia.
2. Hyperkalemia, hypercapnia, diphtheria and influenza.
3. Degenerative sclerosis, fibrosis, obesity or amyloidosis in the area around sinoatrial node.
4. Drug poisoning (such as digitalis, quinidine, verapamil, propyramide, amiodarone, beta blockers, etc. ) and high dose of propafenone can also cause it, but most of them are temporary.
5. Can be seen in healthy people with increased vagus nerve tension or carotid sinus allergy? Atropine test can confirm the diagnosis.
6. Some reasons are unknown, and some may be familial.
7. It is rarely caused by intravenous injection of magnesium sulfate (it cannot be ruled out that the injection speed is too fast), and hypokalemia can also occur (< 2.6 mmol/L =).
8. A few patients can have atrioventricular block at the same time, which is progressively aggravated, which is called double-knot syndrome.
The pathogenesis of 1 1 is that the excitation potential emitted by the sinoatrial node is very small, which cannot be recorded on the body surface electrocardiogram, and can only be recorded by the sinoatrial node electrogram. The excitement from the sinoatrial node is transmitted to the surrounding atrial muscles through the sinoatrial node area, which depolarizes the atrial muscles and produces atrial waves, namely sinus P waves, thus indirectly measuring the activity of the sinoatrial node. Sinus atrial block is different from sinus arrest. The sinoatrial node is still excited on time and regularly, but when the excitement spreads from the sinoatrial node area to the atrial muscle, the conduction is delayed or unable to conduct, which is called efferent block. The former showed first-degree and second-degree sinus block, while the latter showed second-degree sinus block or third-degree sinus block.
12 clinical manifestations of sinoatrial block; Sinus atrial block may appear temporarily, persist or recur. Patients with sinus block often have no symptoms, but also mild palpitation, fatigue and "missed heartbeat". Cardiac auscultation can find arrhythmia, bradycardia and "missed heartbeat" (long interval). If you repeatedly attack or block for a long time, and you can't escape, you may have dizziness, syncope, coma, Asperger's syndrome and so on. In addition, there are clinical manifestations of primary disease.
The complications of 13 sinus atrial block, such as repeated attacks or long duration of sinus atrial block, may lead to syncope, hypotension, Asperger's syndrome and other complications.
The examination of 14 sinus atrial block mainly depends on the diagnosis of ECG. Sinus atrial block can be divided into first degree, second degree, height and third degree according to ECG characteristics.
14. 1 first degree sinus node block refers to the prolonged conduction time from sinus node to atrial cavity. Because the potential of sinoatrial node is too small to be displayed on ECG, it is naturally impossible to measure the conduction time of sinoatrial node. Only when the first-degree sinus atrial block suddenly disappears can the diagnosis be made. Diagnosis can be made in the following two situations.
(1) When the first-degree sinus atrial block and the second-degree sinus atrial block coexist, the diagnosis can sometimes be made on the electrocardiogram. It is characterized by a long interval after sinus rhythm without sinus arrhythmia. It is longer than one sinus cycle and shorter than two sinus cycles (that is, the long interval is less than twice the normal sinus cycle), so it can be inferred that the normal sinus rhythm before the long interval is the first degree sinus atrial block, and the long interval without sinus P wave is the second degree sinus atrial block.
(2) When a second long interval is found after the long interval, and the second long interval is three times as long as the sinus cycle, it can be diagnosed as first degree sinus atrial conduction block. According to this, it can be clearly distinguished from sinus arrest, sinus arrhythmia and untouched atrial premature beats, which makes the diagnosis of sinus atrial block more reliable.
14.2 second-degree sinus node block 14.2. 1 (1) second-degree type I sinus node block is also called Venn's second-degree sinus node block or progressive sinus node block. The sinoatrial node phase (SP interval) refers to the time when the excitement of sinoatrial node propagates to the surrounding atrial muscles (P) through the sinoatrial node area, also known as the sinoatrial node conduction time (SP conduction time). However, the conduction of sinoatrial junction can not be used as a reference for the PR interval of atrioventricular block, and the second-degree type I sinoatrial block can only be analyzed by the change of PP interval.
According to the change characteristics of PP interval, ⅱ degree ⅰ sinus node block can be divided into three types, namely typical Venn type, variant Venn type and atypical Venn type.
① Typical Venn's sinus block: also known as Okada Ⅰ I sinus block.
A. Mechanism: During the descending process of the excitement from the sinus node, the conduction speed gradually slows down until it is completely blocked, and it cannot be transmitted to the atrium, which is a manifestation of the gradual attenuation of the conduction function. It may also be caused by pathological prolongation of relative refractory period and absolute refractory period, especially the pathological prolongation of relative refractory period. This phenomenon appears again and again.
B. ECG characteristics: A. It must be sinus rhythm and sinus P wave. B. there is a gradually shortened PP interval, followed by a long PP interval, and so on. C-long PP interval is less than 2 times of the shortest PP interval (Figure 1).
When the regular sinus rhythm has second-degree type I sinus atrial block, the regularity of each cycle is easy to identify, but when most sinus rhythms have different degrees of arrhythmia, it increases the difficulty in diagnosing the block cycle.
In practical work, when PP interval changes regularly, it can be analyzed according to the following steps (Figure 2):
A. Measure the time limit of a block cycle: that is, the distance of the first sinus P wave after two consecutive block cycles (long PP interval). In each blockade period, this time limit should be equal or multiple.
B. measure the distance of the shortest PP interval in a block period.
C. Remove the time limit of the blocking period with the shortest PP interval: that is, get the sinus cycle number of the blocking period (if it is a decimal, round it to an integer).
D. Subtract the number of known tachycardia intervals in a block cycle from the number of sinus cycles obtained in C: equal to the number of tachycardia intervals disappeared.
E. Divide the time limit of one block cycle by the number of sinus cycles obtained in c: equal to the interval of one sinus cycle.
② Variant Venn's sinus block: also known as Okada type II sinus block.
A. Mechanism: At the beginning of Venn's cycle, the conduction time (SP conduction time) of sinoatrial node is gradually prolonged, while the increment of conduction interval of sinoatrial node is gradually reduced, and it is increased before sinus excitation can not be conducted downwards. The reason is that retrograde and occult conduction occurs during the downward conduction of sinus excitation, which leads to unexpected prolongation of sinoatrial conduction of sinus excitation.
B. ECG characteristics: A. It must be sinus rhythm and sinus P wave. B. the sinus PP interval gradually shortens, and then the PP interval remains unchanged or slightly longer. Finally, there is a long interval without sinus P wave. C long interval without sinus p wave: that is, the long PP interval is slightly shorter than two sinus cycles (fig. 3).
③ Atypical Venn's sinus block: also known as Okada ⅲ sinus block.
When atypical Venn's sinus block occurs, the increment of sinus conduction does not decrease gradually, but increases gradually. On ECG, the PP interval is gradually prolonged, and then suddenly it is obviously prolonged to a long interval without sinus P wave, which is slightly shorter than two sinus cycles.
Due to atrial leakage, the ratio of second-degree type I sinus conduction is not1:1. It can be performed in various proportions, just like second-degree type ⅱ sinus node block. For example: 3∶2, 4∶3, 5∶4, etc. , can form "two laws", "three laws", or 2∶ 1, 3∶ 1 and so on. Can be manifested as sinus bradycardia.
The characteristic of second degree type I sinus atrial block is 3∶2 conduction: the sum of two consecutive long PP intervals is equal to the sum of three consecutive short PP intervals, namely P4P5+P5P6P6P6P6P1P2+P2P3+P3P4, or P1P4P4P4P6. The more times this rule appears in the same ECG, the greater the reliability of diagnosis. When it appears continuously, it shows various PP intervals with alternating length.
The difference between repeated 3∶2 Venn sinus block and second degree sinus block is that the PP interval of the former is gradually shortened, which has the characteristics of periodicity; The PP interval before the long interval of the latter is equal.
14.2.2 (2) Second-degree type Ⅱ sinus block ① Mechanism: Second-degree sinus block is caused by pathological prolongation of relative refractory period and absolute refractory period at the sinus-atrial junction, and the former is dominant, and the latter is dominant, so that single sinus excitement cannot be introduced into the atrium. Second-degree type ⅱ sinus atrial block: there are two kinds of regular conduction ratio (fixed conduction ratio) and irregular conduction ratio.
② Ordinary second-degree sinus atrial block with regular conduction ratio (i.e. fixed):
A.2∶ 1 conduction second degree type Ⅱ sinus block: rare. ECG shows that there is an atrial leak after every sinus P wave, and the conduction ratio is regular (i.e. there is a sinus block), which is 2∶ 1 conduction. When the heart rate is slow (30 ~ 40 beats/min), it is very similar to sinus bradycardia. If the sinoatrial node potential is not recorded directly, it is difficult to distinguish the two. After physical activity or atropine injection, the improvement of sinus conduction can be converted into 1∶ 1 conduction, and the heart rate will suddenly increase by 1 times, so it can be diagnosed as second-degree type ⅱ sinus conduction block with 2∶ 1 conduction.
B.3∶2 second degree type Ⅱ sinus atrial block, with constant conduction ratio of 3: 2 or 4: 3 or 5: 4: that is, sinus atrial block occurs every 2 or 3 or 4 sinus beats. Electrocardiogram showed that there was a missed beat after two or three or four sinus P waves, and there was no PQRST wave group. This long interval is twice that of its short PP interval. The PP interval between sinus beats is equal.
C. ECG characteristics of regular second-degree type ⅱ sinus atrial block: A. sinus P wave. B. A long interval suddenly appears in the conventional PP interval, during which there is no PQRST wave group. C There is a fixed ratio between the conventional PP interval and its subsequent long interval, such as 2∶ 1 or 3∶2 or 4∶3 or 5∶4 (Figure 4). D. the long PP interval is an integer multiple of the short PP interval, generally 2 times.
③ The electrocardiogram of type ⅱ sinus atrial block with irregular conduction ratio showed that a long interval without sinus P wave suddenly appeared in a series of sinus rhythm, and the long interval and PP interval were just twice as long as the PP interval of sinus cycle. Its conduction ratio is not fixed, and it can be 2∶ 1, 3∶2 or 4∶3. The conduction ratio should be pointed out in diagnosis. This type is more common (Figure 5).
14.2.3 (3) Second-degree type III sinus block The second-degree type III sinus block is a second-degree sinus block with irregular sinus conduction interval.
The ECG characteristics showed that PP interval was different, similar to sinus arrhythmia. If it appears alternately or intermittently with the second degree I sinus block, it is more supportive of the second degree III sinus block.
14.3 high sinus atrial block refers to the fact that two or more sinus excitations cannot be introduced into the atrium.
Electrocardiogram characteristics:
① Sudden appearance of long PP interval in sinus rhythm, which is equivalent to 3 times, 4 times or 5 times of short PP interval, can be diagnosed as 3∶ 1, 4∶ 1, 5∶ 1 sinus atrial block, or collectively referred to as high sinus atrial block. The conduction ratio should be pointed out in diagnosis.
② The conduction ratio of high sinus atrial block can be constant, such as 3∶ 1 conduction, or several conduction ratios can exist at the same time, and the lowest and highest conduction ratios should be indicated respectively in diagnosis.
③ Because high sinus atrial block means that more than two sinus excitations can't be introduced into the atrium, which will cause long-term cardiac arrest, so in general, escape or escape rhythm will inevitably appear. If atrioventricular junction escape occurs, it is easier to form escape capture rhythm and repetitive beat rhythm.
14.4 third-degree sinus node block (complete sinus node block) means that sinus excitation is completely blocked in the sinus node area and cannot be conducted downwards. Electrocardiogram characteristics:
(1) Sinus P wave disappears completely, so it is difficult to distinguish it from sinus arrest, and sometimes they can coexist.
(2) At this time, the basic rhythm is mostly emitted from the ectopic rhythm point of the heart, which excites and controls the heart. Such as atrioventricular junctional rhythm or ventricular autonomic rhythm. If atrial escape rhythm appears, it is helpful to the diagnosis of third degree sinus atrial block.
(3) Sometimes the diagnosis can be made indirectly by atropine test: the diagnosis can be made after atropine is injected intravenously and converted into second-degree sinus atrial block.
14.5 second degree type Ⅱ sinus block combined with first degree sinus block after one complete block. The function of sinoatrial node area is improved by rest. The time for sinus excitation of primary sinus atrial block to pass through the sinus atrial junction is shortened. The long PP interval of simple second degree sinus atrial block is twice as long as the short PP interval. However, when combined with first degree sinus atrial block, the long PP interval is shorter than twice PP interval, so it can be diagnosed as second degree type II sinus atrial block combined with first degree sinus atrial block.
When the second-degree and first-degree sinus block is combined with the first-degree sinus block, the PP interval is shorter than twice the PP interval due to Venn phenomenon, so it is difficult to diagnose whether the first-degree sinus block is combined with the second-degree and first-degree sinus block.
15 diagnosis of first-degree sinus node block is characterized by prolonged conduction time of sinus node, which is difficult to be diagnosed by body surface electrocardiogram; Second degree sinus atrial block can be diagnosed according to the history, symptoms and ECG manifestations. The third degree sinus atrial block is characterized by the disappearance of sinus P wave, which is difficult to distinguish from sinus arrest.
16 differential diagnosis 16. 1 2 differential diagnosis between type I sinus atrial block and sinus arrhythmia Because of the different PP intervals of variant Venturi sinus atrial block, it is sometimes difficult to distinguish it from sinus arrhythmia. According to the following points can be determined:
(1) must be the sinus excitation period calculated by Venn's cycle: the ladder diagram of PP time similar to Venn's cycle in ECG leads in this period is basically consistent with the diagnostician, so this type of sinus atrial block can be diagnosed.
(2) Repeat the Venturi cycle.
(3) In sinus arrhythmia, the PP interval is related to respiration, which is gradually shortened at first and then prolonged. However, the PP interval changes of this kind of conduction block are regular and gradually shortened. Finally, a long interval nearly twice as long as the short PP interval appears.
16.2 The difference between second-degree type ⅱ sinus block and 3∶2 second-degree type ⅰ sinus block may be short PP interval and long PP interval alternately, but the long PP interval of second-degree type ⅰ sinus block is less than twice as long as the short PP interval. The long PP interval of 3∶2 second degree sinus atrial block is twice as long as the short PP interval.
16.3 second degree type Ⅱ sinus atrial block and sinus premature beats; The long PP interval of sinus premature beats is not twice as long as the short PP interval. However, the PP interval of type II long interval of 3∶2 sinus atrial block is exactly twice as long as that of sinus.
16.4 the difference between second-degree type ⅲ sinus block and sinus arrhythmia is that the PP interval of second-degree type ⅲ sinus block is suddenly shortened and suddenly extended, which has nothing to do with the respiratory cycle. However, in sinus arrhythmia, the PP interval is gradually shortened and prolonged, which is related to the respiratory cycle, with short inspiratory time and long expiratory time.
16.5 The distinction between sinus arrest and sinus arrest is generally not obvious, and the length of PP interval is not multiple. It is rare that sinus arrest and cardiac arrest interval are the same in an ECG. However, in high sinus atrial block, regardless of the degree of block, the long PP interval is always an integer multiple of the short PP interval. Moreover, long PP intervals with the same length can be repeated. When sinus arrest occurs, low rhythm points are often suppressed, and it is generally not easy to escape. However, in high sinus atrial block, the cardiac arrest time is too long, and it is often easy to appear the rhythm of atrioventricular junction escape and escape or ventricular escape and ventricular escape.
16.6 Differential diagnosis between third degree sinus atrial block and persistent sinus arrest; Third-degree sinus atrial conduction block sometimes appears atrial escape rhythm or escape; Sinus arrest, without atrial escape or escape rhythm, is a pathological factor to inhibit the autonomy of sinus node and ectopic atrial pacing point. But people with atrial escape rhythm are not necessarily sinus atrial block. Patients with sinoatrial block may not have atrial escape rhythm, so it is difficult to distinguish them. In dynamic electrocardiogram or ECG monitoring, sinus arrest can be diagnosed if there is short or long sinus arrest before P wave is not seen for a long time. If first or second degree sinus atrial block has occurred, it can be diagnosed as third degree sinus atrial block.
16.7 The differences between third-degree sinus atrial block and sinus ventricular conduction are as follows:
(1) sinus atrial block can have atrial escape rhythm, while the latter does not.
(2) The rhythm of atrioventricular junction is the basic rhythm of sinoatrial block, so QRS wave is supraventricular, while the latter is wide and deformed.
(3) The latter is often accompanied by hyperkalemia-induced sharp T wave, while the former is not.
(4) If there is hyperkalemia, or the diseases that lead to hyperkalemia can be found clinically, diffuse complete atrial conduction block will often be formed, which will cause sinus conduction, but it has little effect on sinus node.
Treatment 17 sinoatrial block 1. The treatment of sinoatrial block is mainly to treat the primary disease.
2. those who appear temporarily and have no symptoms can be closely observed? Most patients can return to normal without special treatment.
3. For frequent, repeated, persistent attacks or obvious symptoms? Atropine 0.3 ~ 0.6 mg can be taken orally, three times a day; Or intravenous injection or subcutaneous injection of atropine 0.5 ~ 65438 0 mg. Oral ephedrine 25mg, 3 times a day. Oral isoproterenol (wheezing) 10mg, 3 times a day.
4. In severe cases, isoproterenol 1mg can be added to 200ml of 5% glucose or 100ml for slow intravenous drip.
5. For those who have syncope, Asperger's syndrome and drug treatment is ineffective? Implantable artificial pacemaker should be installed in time.
18 Prognostic Sinus-Atrial block, if accidental, is mostly caused by functional vagal tone increase, and frequent or persistent attacks are mostly organic. The ventricular rate is more than 50 beats/min, the duration is short, there is no syncope and Asperger's syndrome, and the general prognosis is good. If the elderly or patients with advanced heart disease have frequent or persistent sinoatrial block, if there is no escape rhythm, Asperger's syndrome can occur and the prognosis is poor.
19 to prevent sinoatrial block 1. Actively treat the primary disease? The key to prevent the disease is to control and eliminate the primary cause in time.
2. Rational use of digitalis preparation, quinidine and other antiarrhythmic drugs.
3. Regular daily life, reasonable diet, good mood, proper physical exercise, and smooth blood flow.
Related drugs: digitalis, quinidine, verapamil, propafenone, amiodarone, atropine, magnesium sulfate, ephedrine, isoproterenol, adrenaline and glucose.
The recovery treatment of sinus atrial block at Neiguan point is very obvious for arrhythmia, such as sinus tachycardia. Generally, the heart rate can be from 150 ~ 3 ~ 5 minutes after acupuncture. ...
For patients with arrhythmia, such as sinus tachycardia, the recovery of yin dimension is very obvious, usually appearing 3 ~ 5 minutes after acupuncture, and the heart rate can be from 150 ~ ...
Treatment of sinoatrial node block by selecting more points
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