Diagnostic points of solid premature beats:
1. Early onset of QRS wave group with wide deformity, time limit >0.12 seconds in adults and >0.10 seconds in children, T wave and QRS wave group
2. No P waves associated with premature beats;
3. Retrograde P’ waves may be located after the QRS wave group, with RP’>0.20 seconds;
4. If the morphology of QRS wave groups of premature beats is the same in the same lead and the pairing time is equal, it is a monogenic ventricular premature beat; if the morphology of QRS wave groups of premature beats is fixed in 2 or 3 types and the pairing time is not equal, it is a multi-source ventricular premature beat, which is mostly seen in patients with organic heart disease.
5. The compensatory phase is complete
Judgment of the point of origin of ventricular premature beats
1. Premature ventricular contractions originated from the right ventricle: the main wave direction of the QRS wave is upward in leads V5 and I and downward in lead V1, which is similar to the waveform of left bundle branch block.
2. Premature beats originating from the left ventricle: the main wave of QRS wave is directed upward in lead V1 and downward in leads V5 and Ⅰ, i.e. similar to the right bundle branch block waveform
3. Ventricular premature beats originating from the septum: the QRS waveform in lead I is biphasic;
4. Ventricular premature beats with apical origin: QRS waves in leads II, III and aVF are downward, while those in leads aVL and aVR are upward (if the origin is in the apical part of the right ventricle, the main wave in lead aVR is downward);
5. Premature ventricular contractions originating from the base of the heart: QRS waves in leads II, III and aVF are upward, and waves in leads aVL and aVR are downward.
6. Ventricular premature beats originating from the anterior ventricular wall: the main waves of QRS waves in leads V1 to V5 are downward;
7. Ventricular premature contractions originating from the posterior ventricular wall: the main waves of QRS waves in leads V1-V5 are upward;
The number of ventricular premature contractions is secondary to the origin and morphology of the ventricular premature contractions. Multi-origin, cascade is more dangerous than monogenic. Ventricular prematureness originating from the right and left ventricular outflow tracts and without organic heart disease is mostly idiopathic and can be eradicated by ablation. The side effects of long-term pharmacological control are significant and have arrhythmogenic effects.
Lown classification of ventricular premature contractions: (mainly for risk stratification of ventricular premature contractions in acute myocardial ischemia)
Class 0: no ventricular premature contractions;
Grade I: Occasional, less than 30 beats per hour or less than 1 per minute
Grade II: frequent, more than 30 beats per hour or more than 6 beats per minute
Grade III: multi-source ventricular pre-term contractions.
Grade ⅣA: paired ventricular anterior contractions, recurrent.
Grade IVB: Recurrent ventricular preterm contractions in bunches (three or more premature ventricular contractions).
Grade V: Pre-phase contractions with the R wave falling on the T wave of the previous sinus excitation.
Principles of treatment of premature ventricular contractions
Premature ventricular contractions are one of the common cardiac arrhythmias. It can be seen in normal individuals and in patients with heart disease. The principles of its management are.
1. No organic heart disease and no symptoms such as palpitations do not require drug treatment;
2.No organic heart disease, but there are symptoms can be treated with drugs;
3, with organic heart disease, regardless of whether there are symptoms need drug treatment.
(Organic heart disease is common: coronary heart disease, hypertensive heart disease, cardiomyopathy, wind heart disease, etc.)
Treatment of premature ventricular contractions
Premature ventricular contractions are the most common arrhythmia and can occur in both normal and cardiac patients. The need for treatment of ventricular premature beats depends mainly on the cause. If it occurs in normal people, it is often induced by emotional stress, mental tension, excessive fatigue, indigestion, smoking, drinking strong tea or coffee, and if there are no obvious symptoms, drug treatment is not necessary. If the patient has obvious symptoms, treatment should be aimed at eliminating the symptoms. Alleviate the patient’s concerns and anxiety and avoid triggering factors such as smoking, coffee, stress, etc. Medications should be β-blockers or mexilate, and avoid the application of class IC and III antiarrhythmic drugs as much as possible.
Premature ventricular contractions due to organic heart disease are commonly seen in patients with coronary artery disease, cardiomyopathy, rheumatic heart disease and mitral valve prolapse. Premature ventricular contractions are most often indicated as pathologic if the following conditions are present on the electrocardiogram.
(i) multiple sources of premature ventricular contractions.
(2) Paired or consecutive ventricular premature contractions.
(3) Premature ventricular beats appearing on the T wave of the previous beat (i.e., RonT phenomenon) with an interval of less than 0.40 seconds. The above three conditions often induce ventricular tachycardia or ventricular fibrillation and must be treated promptly.
④Extra wide ventricular premature beats with QRS interval ≥ 0.6 seconds.
⑤ Extra short ventricular premature beats, i.e. QRS wave group amplitude ≤1,0 mV in each lead of ventricular premature beat abnormality.
(6) Ventricular premature beats with significant tangential QRS wave groups and irregular ascending or descending branches.
(7) The T wave of ventricular premature beats is sharp, the two branches are symmetrical, the T wave direction is consistent with the main wave direction of the QRS wave, and the ST segment is horizontally altered.
(8) Parallel rhythm type ventricular premature beats.
⑨ Premature beat index is less than 1.
Ventricular premature beats on a graph with myocardial ischemia or myocardial infarction.
The treatment of pathological premature ventricular contractions starts with the treatment of the cause. Premature contractions tend to decrease or disappear with the improvement of the underlying disease. If symptoms are significant, the following medications may be used.
①Lidocaine, procainamide, and bromobenzyme, which are more effective for premature ventricular contractions. Especially acute myocardial infarction with premature ventricular contractions.
② β-blockers, phenytoin sodium, quinidine, isoptin, etc., are effective for all kinds of premature beats. Those with bronchial asthma should not use β-blockers.
③Atropine can be given for bradycardia with premature beats.
④Digitalis drugs: effective for premature beats caused by heart failure. For premature beats caused by digitalis toxicity, in addition to stopping digitalis drugs, potassium chloride and phenytoin sodium can be given to obtain control.
⑤ The incidence of sudden cardiac death is higher in patients with post-myocardial infarction or cardiomyopathy complicated by premature ventricular contraction, especially when there is also a significant decrease in left ventricular ejection fraction, the risk of sudden cardiac death will be greatly increased. The application of certain antiarrhythmic drugs to treat ventricular prematureness after myocardial infarction is associated with a significant increase in sudden death and total cardiovascular mortality instead. The reason for this is that these antiarrhythmic drugs have arrhythmogenic effects of their own. Therefore, class I drugs should be avoided for the treatment of post-myocardial infarction ventricular prematureness. β-blockers, although not as effective for ventricular prematureness, can reduce the incidence of sudden death after myocardial infarction. Amiodarone is effective in suppressing ventricular prematureness, but attention should be paid to the possibility of torsional ventricular tachycardia.
(6) If drug therapy is ineffective, radiofrequency ablation may be considered as appropriate.
(7) Some may be at risk of SCD, and then an ICD may be installed as appropriate.