Sinus contraction

Introduction to sinus pretemporal contraction Sinus presurgical contraction (sinusextrasystole) is also known as sinus premature contraction (sinusprematurebeat), sinus node reentry pre-contraction. Sinus agitation recurs in the sinus node 1 or 2 times, forming a sinus pre-contraction. basic knowledge The proportion of illness: the incidence rate is about 0.01%-0.05%, more common in the elderly Susceptible people: no special people Mode of infection: non-infectious complication:

Sinus premature contraction etiology

Causes:

The mechanism of sinus pre-contraction changes the definition of pre-systolic contraction, that is, the pre-systolic contraction is not necessarily the excitement of ectopic pacemakers. In some cases, pre-contraction can be derived from normal pacing of the heart. Sinus node, the cause may be related to autonomic dysfunction, fever, metabolism and drugs.

Pathogenesis:

Sinus premature contraction is caused by sinus agonism itself, no need to induce atrial premature contraction, sinus agitation reentry along the sinus node, resulting in sinus pre-systolic contraction, due to the lack of sustained reversal of the reentry loop Pass or forward ability, so excited to return to 1 or 2 times and then terminated.

Sinus premature contraction prevention

1. Actively treat the primary disease and eliminate the cause of pre-systolic contraction, such as correcting electrolyte imbalance and preventing invasion of external sensation.

2. Avoid mental stress, maintain mental optimism, emotional stability; daily life, do not overwork; quit smoking and alcohol, reduce the predisposing factors of the disease; diet, eat less fat and greasy food; active physical exercise, weight control .

Sinus premature contraction complications Complication

No serious complications.

Sinus premature contraction symptoms Common symptoms Painful heart rate increased heart rate

There are no obvious clinical symptoms.

The diagnostic conditions for sinus pretemporal contraction are as follows: (1) The sinus P wave that occurs early is the same as the P wave of the sinus rhythm. 2 There is a fixed inter-law interval. 3 is an equal period of compensation. Symptoms rarely occur in the early stages of sinus, but sometimes the difference between the two heart beats can cause heart palpitations. And sinus arrhythmia, heart palpitations, etc. have a certain similarity, pay attention to identification. The sinus pre-existing itself generally does not require treatment. After the activity, the heart rate increases and disappears.

Sinus premature contraction

ECG features:

1. Early sinus P' wave

The shape, amplitude and time of the P' wave are the same as the P wave of the basal rhythm sinus rhythm on the same lead, depending on whether the sinus agitation to the atrium exit is the same as the basic rhythm sinus rhythm, in most cases The two exits in the atrium are the same, so the P' wave of the sinus premature contraction that is exactly the same as the P wave of the basic sinus rhythm is consistent in each lead, but in rare cases, the sinus phase The excitatory anterior excitability is different from the sinus rhythm excitatory in the atrial exit, and the sinus premature contraction P' wave appears. In addition, the P' wave of the sinus premature contraction can also be accompanied by three The phase of the room is blocked and shaped.

2. PR interval

The PR interval of sinus pre-contraction is equal to the PR interval of the sinus rhythm, which is 0.12 to 0.20 s. If the P' wave in the early sinus occurs in the relative refractory period of the previous heartbeat, interference may occur. Or the delayed PR interval is prolonged. If the P' wave appears in the absolute refractory period of the cardiac cycle, ventricular detachment will occur.

3.QRS wave

The QRS-T waveform of sinus pre-contraction may be the same as sinus rhythm, or may be accompanied by temporal differential conduction, bundle branch block, and pre-excitation syndrome.

4. Inter-law period

Since the reentry loop and the reentry rate are the same, a pre-synaptic fixed sinus premature contraction can be produced, but different degrees of efferent block can occur in the reentry loop.

(1) Second-degree type I efferent block (Wen's phenomenon): P-QRS-T misses before the sinus pre-systolic contraction, and recurrence .

(2) Second-degree type II efferent block: a simultaneous interphase fixation with sinus pre-systolic leakage.

(3) combined height-out block: sporadic, scattered sinus premature contraction.

(4) Complete efferent block: the sinus premature contraction disappears.

5. Compensation interval

The sinus pre-systolic pacing point is very close to the pacing point of the basic sinus rhythm. After the sinus pre-systolic contraction is excited, the basic sinus rhythm pacemaker reconstruction period can be immediately caused. Therefore, the sinus pre-contraction generation is replaced. The interval is equal to a basic sinus rhythm cycle, which is called the equal period compensatory interval, that is, the early P wave and the interval between the first normal sinus P wave (P'-P interval) and the basal sinus rhythm The PP interval is equal, and the equal-period compensation interval is a special type in the generalized incomplete compensation interval.

6. Sinus premature contraction can occur occasionally, frequently or in association with the law.

Diagnosis and differentiation of sinus premature contraction

1. Sinus pre-systolic and sinus arrhythmia

(1) The changes in the cardiac cycle of sinus arrhythmia gradually occur, while the cardiac cycle of sinus pre-contraction is suddenly shortened.

(2) Sinus arrhythmia is closely related to the respiratory cycle. The cardiac cycle gradually prolongs or shortens with the breathing. The frequency of inspiration increases, the frequency of exhalation slows down, and the sinus premature contraction has nothing to do with breathing.

2. Identification of pre-systolic contraction and atrial premature contraction

The P wave pattern of premature atrial contraction is different from the P wave of sinus rhythm. In addition, although the compensatory interval of the former is also incomplete compensatory interval, this compensatory interval is still significantly longer than a sinus cardiac cycle, sinus The P wave and the sinus P wave before contraction can be very similar, but the compensation interval is still significantly longer than a sinus cardiac cycle. The P wave of the sinus premature contraction is exactly the same as the sinus P wave, and there are The period of compensation is intermittent.

3. Sinus pre-contraction dichotomy and 3:2 sinus block

When the sinus conduction was 3:2 block and the sinus premature contraction was found to be paired P-QRS-T, the interval between PP intervals appeared alternately. The key points were as follows:

(1) The long PP interval at 3:2 sinus block is twice as long as the short PP interval, while the sinus pre-systolic bifurcation interval PP interval is not twice as long as the short PP interval.

(2) When the 3:2 sinus block is Wenwen, the long PP interval is less than 2 times of the normal PP interval. At this time, it is difficult to distinguish the sinus pre-contraction dichotomy. Sexual rhythm, and the PP interval of sinus rhythm can be diagnosed as sinus premature contraction if it is equal to the long PP interval in the paired sinus premature contraction; if sinus The short PP interval in the pre-systolic bifurcation is equal, and the diagnosis can be diagnosed as a 3:2 sinus block.

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