Premature ventricular contraction

Introduction to ventricular premature contraction Ventricular premature contraction (ventricularextrasystole) also known as ventricular premature beats (VPBs) referred to as ventricular premature beats, which means that before the sinus agitation has not yet arrived, a certain beat point from the ventricle occurs prematurely, causing ventricular depolarization. , one of the most common arrhythmias. Patients may feel palpitations and discomfort. When the premature ventricular contraction is frequent or bipolar, it may lead to a decrease in cardiac output. If the patient has left ventricular dysfunction, frequent ventricular premature contraction may cause syncope, ventricular phase. The pre-contraction episode lasts too long and can cause angina and hypotension. basic knowledge The proportion of illness: 0.005% Susceptible people: no special people Mode of infection: non-infectious Complications: angina

Premature ventricular contraction

(1) Causes of the disease

Autonomic function factors (25%):

One of the most common causes of ventricular premature contraction is that when the autonomic dysfunction occurs, whether it is vagus nerve excitation or sympathetic nerve excitation, the excitability of the fast and slow fibers of the myocardium can be unbalanced. Period and conduction velocity change, triggering reentry ventricular premature contraction, excessive secretion of catecholamines causes autonomic growth of ventricular autonomic cells, leading to ventricular premature contraction, excessive tobacco, alcohol, tea, coffee, etc. Excessive mental stress, excessive fatigue, long-term insomnia, eating too much, neurasthenia, autonomic dysfunction, menopause and other factors are related to the occurrence of ventricular premature contraction. It should be noted that some patients with early stage of organic heart disease have autonomic dysfunction leading to ventricular premature contraction, which makes it difficult to identify the cause of ventricular premature contraction. It is not easy to assume that ventricular premature contractions in patients with organic heart disease are organic.

Left ventricular intraventricular false chordae (20%):

In patients with ventricular premature contraction without organic heart disease, 56% to 75% of patients with left ventricular false chordae and ventricular premature contraction caused by false chordae were detected by echocardiography. Benign premature contractions, such as infrequent seizures, do not require treatment.

Organic heart disease (30%):

Premature ventricular contraction is also more common in organic factors, such as ischemic cardiomyopathy, coronary heart disease, pulmonary heart disease, rheumatic valvular heart disease, hyperthyroidism, etc.; myocarditis, cardiomyopathy, heart disease of various causes Depletion, whether it is acute diffuse cardiomyopathy or focal lesions, may cause excitability of ectopic rhythm points or affect myocardial fiber refractory period or conduction velocity due to ischemia, hypoxia, inflammatory damage, etc. Contraction before sexual sex. (1) Myocarditis: The prevalence of ventricular premature contraction is 34.3% to 81.3%, and the pre-ventricular contraction is 8% to 28.1%. (2) Dilated cardiomyopathy: the incidence of ventricular arrhythmia is as high as 83% to 100%, and the incidence of complex ventricular arrhythmia (Lown III) is 58% to 87%, especially when EF<0.40 Easy to induce ventricular arrhythmia. (3) Acute myocardial infarction: ventricular premature contraction is the most common in the early stage of acute myocardial infarction, complications of recovery and late arrhythmia, especially in the first few hours of onset, acute myocardial infarction in the mid-ventricular phase of the intensive period The detection rate of anterior contraction was 63.2%. In the early years, R-on-T type ventricular premature contraction was a "harsh" for inducing rapid ventricular tachycardia and ventricular fibrillation. According to reports from Fuwai Hospital, acute myocardial infarction Patients with concurrent ventricular tachycardia and ventricular fibrillation can be confirmed to have only 11% and 6% of R-on-T type ventricular premature contractions. In recent years, R-on-P type chambers have been considered. Pre-sexual contraction is also dangerous in the acute phase. (4) mitral valve prolapse: 75% of patients may have ventricular premature contraction, and the incidence of ventricular premature contraction after active treadmill exercise test can reach 58%. (5) Hypertensive left ventricular hypertrophy: In the absence of cardiac dysfunction, the incidence of ventricular premature contraction and short ventricular tachycardia is 2% to 10%. If there is cardiac dysfunction, the incidence can be significantly increased. (6) Hyperthyroidism: The incidence of ventricular arrhythmia is about 14%, and ventricular premature contraction is more common. (7) heart failure: often combined with a variety of arrhythmia, the most common ventricular arrhythmia, more complicated by left heart failure, the severity of heart failure and severe arrhythmia have a certain correlation.

Electrolyte balance imbalance (12%):

(1) hypokalemia: easy to cause increased self-discipline, can occur pre-atrial contraction, ventricular premature contraction, ventricular and supraventricular tachycardia and atrioventricular block. (2) low blood magnesium: low blood magnesium is easy to form reentry arrhythmia, can also induce arrhythmia related to triggering activities, arrhythmia caused by hypomagnesemia is the most common ventricular arrhythmia.

Drugs (12%):

Many drugs and antiarrhythmic drugs can cause arrhythmia, the most common is digitalis, ventricular premature contraction is most common in digitalis toxic arrhythmia, and it is also the earliest, the incidence rate is 50% to 60%. Frequent, two-law, triple-law, multi-source, etc., atrial fibrillation with ventricular premature contraction, the triple law is a characteristic manifestation of digitalis poisoning; two-way ventricular premature contraction is also digitalis poisoning The characteristics of multi-source or polymorphic ventricular premature contractions often suggest severe digitalis poisoning. The occurrence of ventricular premature contraction has a large diurnal variation. It is usually more common in the morning than in the night. It is more common after meals than before meals. Therefore, it is necessary to record the 24h electrocardiogram to truly understand the frequency of ventricular premature contraction. The frequency of pre-contraction is different every 24h or hour.

(two) pathogenesis

Most ventricular premature contractions are caused by reentry, and a small part is caused by autonomic abnormalities and triggering agonism.

Ventricular premature contraction prevention

1. Actively treat the primary disease, eliminate the causes of pre-systolic contraction, such as correcting electrolyte imbalance, improving myocardial blood supply, improving cardiac function, etc.; preventing exogenous; correct, timely medication.

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 has a diet, eat less fat and greasy food.

3. Actively exercise and control weight.

Ventricular premature contraction complications Complications

If there is a frequent ventricular contraction, it can cause dizziness, fatigue, and even angina.

Ventricular premature contraction symptoms common symptoms ulnar artery or radial artery... angina psychiatric palpitations heart sound abnormalities

Patients may feel palpitations and discomfort. When the premature ventricular contraction is frequent or bipolar, it may lead to a decrease in cardiac output. If the patient has left ventricular dysfunction, frequent ventricular premature contraction may cause syncope, ventricular phase. The pre-contraction episode lasts too long and can cause angina and hypotension.

Examination of ventricular premature contraction

Mainly based on ECG examination.

1. Typical ECG characteristics of ventricular premature contraction

(1) The QRS-T wave group that appears earlier: there is no ectopic P wave associated with it.

(2) QRS complex large deformity: coarse or blunt, with a time generally greater than or equal to 0.12 s.

(3) The T wave direction is often opposite to the direction of the QRS wave main wave: it is a secondary T wave change.

(4) There is a complete compensatory interval.

(5) In the case of ventricular premature contraction caused by the same ectopic excitatory: the ventricular premature contraction has a fixed interphase interval (matching interval, pairing time) with the previous heartbeat.

2. Detailed description of typical ECG characteristics of ventricular premature contraction

(1) QRS wave: its morphology depends on the origin of the ventricle and the conduction of agonism in the ventricle. It can occur in any part of the ventricle. The time limit of the QRS wave is often >0.12s, usually not more than 0.16s; for example, >0.16s , suggesting that the pathological ventricular premature contraction, when the ventricular fusion wave occurs, its QRS wave morphology can be between the sinus and ventricular premature contraction QRS wave.

(2) Secondary ST-T changes.

(3) P wave: premature ventricular contraction is rarely transmitted back to the atria, but before and after the ventricular premature contraction, the sinus impulse is still emitted and the atrium is excited.

(4) Inter-term contraction of ventricular premature contraction: it is fixed and can remain unchanged for many years, but in the case of sinus arrhythmia, it can be seen that when the sinus rhythm is slow, the interval can be slightly extended. When the sinus rhythm is slightly faster, the inter-law interval may be shorter, and the difference between the inter-laws on the same lead may not be greater than 0.08 s.

(5) Intermittent compensation: Most of them are complete compensatory pauses, and a few are incomplete compensatory pauses. They are seen in the premature ventricular contraction and transmitted back to the atria, so that the sinus node is depolarized in advance to re-arrange the rhythm; Stroke ventricular premature contraction with stroke ending: ventricular premature contraction blocks an ongoing Venturi cycle; ventricular premature contraction occurs during sinus arrhythmia, atrial fibrillation, and its compensatory interval Can be incomplete; insertion ventricular premature contraction without compensatory interval.

3. Location diagnosis of ventricular premature contraction

(1) Left ventricular premature contraction: the ventricular premature contraction QRS main wave is in the I, V5 lead down, in the III, V1 lead, similar to the complete right bundle branch block.

(2) right ventricular premature contraction: ventricular premature contraction QRS main wave in the I, V5, V6 lead upwards, in V1, V2 lead down, similar to complete left bundle branch block.

(3) ventricular premature contraction at the base of the heart: the systolic pre-systolic QRS main wave is upward in the II, III, and aVF leads, and is down in the aVR lead.

(4) apical ventricular premature contraction: ventricular premature contraction QRS main wave is downward, in the aVR lead upwards.

4. Special types of ventricular premature contraction

(1) Metabolic ventricular premature contraction: Intermittent ventricular premature contractions (interpolated VPBs), also known as insertional ventricular premature contractions, ECG characteristics:

1 The large malformed QRS-T wave that appears in advance is inserted between two sinus beats, and the distance between the two sinus beats is equal to a sinus cardiac cycle.

2 no compensation interval.

The sinus P'R interval after 3 ventricular contractions was normal or prolonged.

4 When the P'R interval is prolonged: the RR interval between the two sinus beats after ventricular contraction is slightly longer than a sinus P'P interval.

The 5-position ventricular premature contraction can occur in the first half of a sinus cardiac cycle, or in the second half, and occurs in the second half.

More than 6 occurred in sinus bradycardia.

7 When the sinus rhythm is slow: there may also be two ventricular contractions inserted between the two sinus beats.

(2) The premature contraction of the ventricular premature contraction appears: if a ventricular premature contraction occurs after several sinus rhythms, it is called pre-systolic contraction, and its interval is fixed, such as each A ventricular premature contraction after sinus rhythm is called ventricular premature contraction, such as a ventricular premature contraction after two sinus rhythms, called ventricular premature contraction, and so on. However, there must be three groups in succession. There are two manifestations of ventricular pre-systolic triads:

There was 1 ventricular premature contraction after 12 sinus beats: 3 consecutive groups.

There were 2 ventricular premature contractions after 21 sinus beats: 3 consecutive groups.

(3) The law of the second law of ventricular premature contraction: constant after the long cardiac cycle, and the formation of the ventricular premature contraction two-law of the inter-term interval, called the rule of the law (rule of bigeminy) , ECG performance: ventricular premature contraction only occurs after a long RR interval, the long interval after ventricular premature contraction creates conditions for the next slow ventricular premature contraction, and the cycle begins again. Interim fixed unilateral ventricular premature contraction bivariance, which is common after a pre-systolic contraction interval, after a 2:1 atrioventricular block or after a long RR interval of atrial fibrillation.

(4) The reverse rule of bigeminy: should be called non-slow ventricular premature contraction, rarely seen, ECG performance: interventricular premature contraction Not long, can be very short, the RR interval of ventricular contraction is not long (Figure 5), if accompanied by sinus arrhythmia, ventricular premature contractions occur after a short cardiac cycle.

(5) ventricular premature contraction and continuation: refers to the two ventricular premature contractions appear continuously, the form of the two ventricular premature contractions on the electrocardiogram may be slightly different, if three ventricular premature contractions occur continuously It is called short ventricular tachycardia (non-sustained ventricular tachycardia).

(6) R-on-T phenomenon (R-on-T syndrome): premature ventricular contraction occurring in the systolic phase occurs on the T wave of the previous cardiac cycle, in the T wave crest or anterior branch or The posterior branch occurs when the ventricular repolarization is incomplete and the ventricle is in a vulnerable period of repetitive agitation. It can be divided into two types, A and B.

Type 1A R-on-T syndrome: short-term ventricular contraction, and normal QT interval before ventricular pre-systolic sinus pulsation, inter-trial contraction and QT When the ratio of the two periods is >1, the R-on-T ventricular contraction is single-shot, and if the ratio of the two is <1, the ventricular premature contraction may be multiple to form a short-ventricular tachycardia.

Type 2B R-on-T syndrome: It is prone to occur when the QT interval is prolonged and the interval between the two is equal. The electrocardiogram appears on the basis of prolongation of the QT interval, and the early ventricular premature contraction occurs R-on- T, can cause transient paroxysmal ventricular tachycardia, but also easy to cause long-term interval, two-law, triple-law, two-way ventricular premature contraction, torsade de pointive ventricular tachycardia, ventricular flutter Movement, ventricular fibrillation, etc., there are also people who have died.

(7) Late diastolic ventricular premature contraction and R-on-P phenomenon: ventricular premature contraction occurs in the late diastolic phase, sinus node impulse has been transmitted to the atria, P wave appears, and the electrocardiogram appears to follow the P wave. A wide malformed QRS wave with a P'R interval <0.12 s, called end-diastolic VPBs. If the QRS wave falls on the P wave, the upper or lower peak is called R. The -on-P phenomenon, also known as late diastolic ventricular premature contraction.

(8) Multi-source ventricular premature contraction (multifocal VPBs): refers to ventricular premature contraction caused by 2 or more ventricular ectopic pacemakers. ECG characteristics:

1 There are two or more ventricular premature contractions of different QRS complexes in the same lead.

2 The inter-law period is not fixed.

3 electrocardiogram can have myocardial damage or digitalis poisoning changes: the emergence of multi-source ventricular premature contractions often suggest organic heart disease, can occur in severe myocardial hypoxia, extensive myocardial infarction, significant Hypokalemia, diffuse cardiomyopathy, digitalis poisoning and other patients.

(9) polymorphic ventricular premature contraction: refers to the ventricular premature contraction in the same lead, its QRS wave amplitude, the morphology is different, but the same interval, polymorphic ventricular phase The clinical significance of anterior contraction is similar to multi-source ventricular premature contraction.

(10) ventricular premature contraction with indoor differential conduction: phased indoor differential conduction can also occur in ventricular premature contraction, but less common, ventricular premature contraction from the same ectopic pacemaker, its morphology It should be the same, but in some cases, the ventricular premature contraction of the same pace point has a wider QRS wave, the ST-T wave changes more or the degree of QRS wave malformation is only slightly obvious or the deformity is reduced. Morphology is different from other ventricular premature contractions.

(11) occult ventricular premature contraction:

1 occult ventricular premature contraction dichotomy: ECG features: ventricular premature contraction of the interphase fixation; the number of sinus beats between the two dominant ventricular premature contractions presents an odd distribution, such as 3 , 5,7,9,11, etc., that is, the number is always 2n 1 , n can be 0 and any positive integer, representing the number of occult ventricular premature contractions in the occult ventricular contraction There is no occult ventricular premature contraction. There is only one (2×0+1) sinus beat between the dominant ventricular premature contractions, which is the usual ventricular premature contraction. Occult impulse, the number of sinus beats between the two dominant ventricular premature contractions is 3 (2 × 1 + 1); two consecutive occult impulses, two dominant ventricular anterior constriction sinus beats The number is 5 (2 × 2 + 1), and the remainder can be analogized. If the previous electrocardiogram has been traced to the dominant ventricular premature contraction, the diagnosis is more certain.

2 occult ventricular premature contraction triple law: ECG features: A. ventricular premature contraction of the interphase fixation; B. 2 dominant ventricular premature contraction between the ventricular pulsation is 2, 5,8,11,14, etc., the number is always 3n+2, n represents the number of occult ventricular premature contractions in the occult ventricular contraction triad; C. If the patient has had a dominant room The diagnosis of the three-joint history of contraction before sex can be more certain.

Occult ventricular premature contraction dichotomy, triad law is mostly seen in patients with structural heart disease, severe myocardial ischemic injury and digitalis poisoning, occult ventricular premature contraction triple law is similar to the second law, mainly intermittent The existence of sexual efferent block, concealing the dominant ventricular premature contraction triple law, other occult insertional ventricular premature contraction dichotomy, triple law, occult multi-source ventricular phase The pre-contraction two-law is similar to the above.

(12) Very short-term intertemporal ventricular premature contraction: this type of ventricular pre-systolic contraction presents a normal QT interval, a very short inter-term interval, R-on-T phenomenon, and the shortest inter-term interval For 240ms, the longest is only 300ms, usually 280ms. The ventricular premature contraction mostly occurs in the T wave anterior branch, the apex or the posterior branch of the previous cardiac cycle, and a few can occur at the junction of the ST segment and the T wave. It is easy to induce very short-term intertemporal polymorphic ventricular tachycardia or ventricular fibrillation. This type of ventricular premature contraction often occurs in patients without structural heart disease, and its mortality is extremely high.

(13) Extra-temporal ventricular premature contraction: seen in slow heart rhythm, such as sinus bradycardia or escape rhythm, with the characteristics of extra-synaptic interval as the main feature, the diagnosis is based on the interval of 0.80s. The longest is 1.15s, but the individual can reach 1.32s. The frequency of such ventricular premature contraction is <75 times/min, which is an accelerated ventricular escape rhythm between ventricular premature contraction and ventricular escape. Category, but because the basic rhythm is too slow, the escape is the relative contraction, and the escape frequency can be different depending on the origin and the individual, but there is no absolute boundary, so the diagnosis can only be compared with the dominant rhythm. It is determined that those who are faster than the dominant rhythm can be excluded from the ventricular premature contraction except for the passive ectopic rhythm.

(14) Inter-incremental ventricular premature contraction (inter-disciplinary ventricle pre-systolic contraction): The electrocardiogram shows a gradual increase in the interval between ventricular premature contractions (ie, gradually prolonged), followed by ventricular premature contraction disappears, so repeated, can be in various conduction ratios, for example: conduction ratio 5:4 is 5 sinus beats, only 4 reentry ventricular premature contractions At this time, the inter-trial contraction of the ventricular premature contraction is gradually prolonged, and there is no reentry ventricular premature contraction after the fifth sinus beat, that is, the ventricular premature contraction occurs once, and then the Venturi cycle is restarted. This shows that two sinus beats appear continuously.

(15) ventricular premature contraction with reentry pathway in the type A alternating Venturi cycle: also known as the inter-trial interval is a type A alternating Venturi ventricular premature contraction.

(16) Pre-internal contraction of ventricular premature contraction (internal ventricle pre-systolic contraction): also known as anti-Wenshi phenomenon in the ventricular pre-contraction reentry pathway Phenomenon), when the anti-Wenshi phenomenon occurs in the reentry path of ventricular premature contraction, the reentry conduction time can be gradually accelerated until the reentry is interrupted, and the inter-trial contraction is gradually shortened until the pre-period contraction occurs. Or two consecutive ventricular premature contractions appear and end the periodic variation of the anti-Wen's cycle, the main points of electrocardiogram diagnosis:

1 to prove the premature contraction of the systolic pre-systolic reentry type.

Interventricular interval of 2-ventricular premature contraction: progressive shortening until the absence of pre-systolic contraction or ending the cycle in the form of repeated heart beats.

The pre-contraction interval of 3-ventricular premature contraction was progressively shortened: but the shortening was fine, the long-term pre-contraction distance was greater than 2 times of the short-term pre-contraction interval, and the change of pre-systolic space was related to the basic heart cycle and was affected by the inter-term interval.

4 should be differentiated from ventricle parallel rhythm and ventricular parallel rhythm with Venturi phenomenon or anti-Wen's phenomenon, the identification of the two:

A. The first interphase contraction after the ectopic beat of the parallel heart rhythm is longer and often different.

B. Parallel heart rhythm The ectopic beat interval is often less than 2 times the short ectopic beat interval.

C. Parallel rhythm ventricular premature contraction interval shortening is more significant.

D. Parallel rhythm ventricular premature contraction spacing is independent of changes in the sinus cycle.

E. Parallel rhythm ventricular pre-contraction spacing is not affected by the pairing interval: the anti-Wenshi phenomenon in the reentry path is often a temporary electrocardiogram.

(17) B-type alternating Venturi cycle in the ventricular premature contraction and reentry pathway: also known as the B-type alternating Venturi ventricular premature contraction.

(18) Four manifestations of double-path conduction in the ventricular pre-contraction reentry pathway:

1 ventricular premature contraction dichotomy (single-source ventricular premature contraction): alternating interval between the length of the interval, also known as the inter-term interval length of the ventricular premature contraction.

2 ventricular pre-contraction two, the triple-law interval is short-short-long alternate or short-long-long alternate.

3 Inter-term interval is a long-short and irregular ventricular premature contraction: At present, reentry agonism is considered to be the main cause of pre-systolic contraction. Most pre-systolic contractions have a fixed interphase interval, and a few may have a reentry path. Wen's, alternating Wen's or anti-Wen's phenomenon makes regular changes in the inter-trial period. This type of ventricular pre-systolic syndrome is rare, and this is a two-way path in the reentry path. The conduction is irregular.

The QRS of the 4 ventricular premature contraction showed an alternating incidence of two forms: the polymorphic ventricular premature contraction, which is represented by the two pathways in the atrioventricular junction (referred to as the A and B pathways, respectively). The expected period and the return speed are the same, so that the joint interval is equal, and there are alternating 2:1 conduction blocks in the A and B paths. When the impulse passes through the A path, the B path blocks; when the next impulse passes the B path, A The path is blocked, so the ventricular premature contraction of the two forms alternates. In addition, the two paths must also have a unidirectional afferent block. Otherwise, the impulse can pass from the A path (or the B path). Enter the B path (or A path), so that it continues to be in the refractory period. At this time, the ECG can only express a form of ventricular premature contraction, which can be seen in digitalis poisoning.

(19) ECG changes after ventricular premature contraction: ventricular premature contraction and atriality, similar to the characteristics of premature contraction, can cause the basic heartbeat after precontraction after premature contraction (mostly sinus Sexual heart rhythm) in the origin, conduction, excitement abnormalities, pre-systolic changes are mainly P'-R interval, QRS wave morphology, time limit and ST-T changes, in a few cases, the impact can reach the pre-period The second or several cardiac cycles after contraction change (usually up to three).

(20) Normalization of ventricular premature contraction QRS complex: refers to the QRS-T wave group of ventricular premature contraction, in some cases, similar to the normal sinus QRS-T wave group; or when there is a bundle The width of the QRS-T wave group at the time of conduction block is reduced, which is close to the normal sinus QRS-T wave group or completely normal.

(21) ventricular premature contraction with retrograde ventricular conduction and recurrent pulsation: the incidence of ventricular premature contraction with retrograde ventricular conduction is actually much higher than the clinical surface electrocardiogram, because it is likely Concealed by the wide deformed QRS-T wave, the ventricular premature contraction seen on the electrocardiogram with incomplete compensatory interval, which is caused by the ventricular premature contraction ventricular conduction reverse sinus node, ECG Performance: A retrograde P' wave can be seen after contraction of the QRS wave before the ventricular stage, and the R'-P' interval usually does not exceed 0.20 s.

(22) ventricular premature contraction with Q wave: ectopic pacemaker occurs in the right ventricle or left ventricle, and there is no Q wave in the ventricular premature contraction. If Q wave appears, it is accompanied by myocardial Infarction, but the electrocardiogram performance QRS wave must present QR type, qR type, qRs type, but not QS type (except aVR lead), ventricular premature contraction with Q wave is related to the location of myocardial infarction.

(23) Frequency-dependent ventricular premature contraction: The occurrence of some ventricular premature contractions is related to the frequency of the basic heart rhythm. There are two types:

1 fast frequency-dependent ventricular premature contraction: when the basic heart rate is accelerated to a certain critical frequency, the number of ventricular premature contractions or ventricular premature contractions increases significantly, and the ventricular premature contraction occurs when the ventricular rate is slowed down. The number decreased or disappeared significantly. The number of ventricular premature contractions accounted for the majority during the day. The distribution of premature ventricular contractions was sparse. The frequency of basic heart rhythm could be sinus tachycardia, atrial tachycardia, atrial flutter. Or atrial fibrillation, the mechanism of rapid heart rate-dependent ventricular premature contraction may be related to increased secretion of catecholamines and adrenaline in the blood.

2 slow frequency-dependent ventricular premature contraction: also known as slow heart rate-dependent ventricular premature contraction, or secondary ventricular premature contraction, which occurs after a long ventricular interval (RR interval), seen in the second degree Atrioventricular block, slow phase of sinus arrhythmia, long interval after atrial fibrillation, and ventricular premature contraction produces a long interval (complete compensatory interval), before the next ventricular period The formation of shrinkage creates conditions.

Diagnosis of ventricular premature contraction

diagnosis

During auscultation, there is a long pause after ventricular premature contraction. The intensity of heart sound before ventricular contraction is weakened. Only the first heart sound can be heard, the pulsation of the radial artery is weakened or disappeared, and the normal or giant a wave is visible in the jugular vein. .

Differential diagnosis

The diagnosis of ventricular premature contraction is not difficult, but should be differentiated from the following arrhythmias.

1. Identification of ventricular premature contraction and atrial premature contraction with indoor differential conduction.

(1) Pre-atrial contraction with differential conduction in the room: the QRS wavefront with its large deformity has an ectopic atrial P' wave, the P' wave is in the same direction as the QRS wave, and the P'-R interval should be greater than 0.12. s; whereas ventricular premature contraction is independent of P wave, P wave can be before or after contraction of QRS wave before ventricular premature, or overlap in QRS-T wave group.

(2) The atrial premature contraction is different from the QRS wave initiation vector of the indoor differential conduction and the ventricular premature contraction: the former is the same as the sinus rhythm, and the latter is different.

(3) Atrial premature contraction with indoor differential conduction: the degree of QRS wave malformation is related to the length of RP interval. If the interval of RP is long, the deformity is lighter. If the interval of RP is short, QRS wave Group malformation is obvious, and there is no such rule in ventricular premature contraction.

(4) The compensatory interval of ventricular premature contraction is often complete, and the compensatory interval of atrial premature contraction with indoor differential conduction is incomplete.

2. Identification of premature ventricular contraction and atrioventricular contraction with premature contraction and differential conduction in the room. When the premature contraction of the atrioventricular junction is accompanied by differential conduction in the room, if there is no retrograde to the atrium, the deformed QRS wave There is no retrograde P' wave before, and there are certain difficulties in identification. The following two points are conducive to the diagnosis of premature contraction in the atrioventricular junction area with indoor differential conduction:

(1) The shorter the pre-systolic contraction interval, the more obvious the QRS wave deformity is.

(2) The wide-profile malformed QRS wave is three-phase in the V1 lead.

(3) Premature contraction of the atrioventricular junction with indoor differential conduction such as retrograde to atrial P' wave: P'-R interval should be <0.12s, then the diagnosis can be confirmed, and the ventricular premature contraction does not have this feature. However, the retrograde P' wave appears after the QRS wave and appears continuously. It is considered that the premature contraction of the atrioventricular junction area is likely to be differentially transmitted indoors, but the ventricular premature contraction cannot be completely excluded.

3. The characteristics of ventricular premature contraction with ventricular fusion wave and multi-source ventricular premature contraction for multi-source ventricular premature contraction are:

(1) The inter-term interval of ventricular premature contraction is not fixed.

(2) The QRS wave morphology is different: the ventricular premature contraction with ventricular fusion wave is associated with the ventricular premature contraction. The fusion wave is rare, most of the ventricular phase The front contraction has no fusion wave, so the QRS wave morphology is mostly the same.

4. The identification of atrial fibrillation with differential differentiation of indoor and ventricular premature contractions is very important. Because of the clinical significance and treatment, such as in the process of taking digitalis, the former suggests that the use of digitalis is not enough, and then The person suggested that the digitalis is excessive, and the identification points of the two are:

(1) ventricular premature contraction interval is equal: while atrial fibrillation with indoor differential conduction is transmitted by atrial fibrillation, usually without a fixed interval.

(2) The initial vector of atrial fibrillation with indoor differential conduction is the same as the initial vector of normal QRS wave, but there is no such rule in ventricular premature contraction.

(3) Atrial fibrillation with differential conduction in the room often presents a three-phase right bundle branch block (rSR' type) in the V1 lead, while ventricular premature contraction is less common.

(4) ventricular premature contraction often occurs in atrial fibrillation with slow ventricular rate, and indoor differential conduction occurs in atrial fibrillation with fast ventricular rate.

(5) The QRS wave with wide deformity and the normal QRS wave alternately appear as the ventricular premature contraction bipolar law, especially for the pre-systolic contraction interval fixation, while the indoor differential conduction generally does not appear in the above rules.

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