premature ventricular contractions in the elderly
Introduction
Introduction to ventricular premature contraction in the elderly Ventricular premature contraction is ventricular activation caused by ectopic pacemakers below the His bundle, which is more common in the elderly, and some may have no obvious clinical symptoms, and some may lead to serious consequences, which cannot be ignored. In the elderly, premature ventricular contractions are more common in patients with structural heart disease, but also in normal people without structural heart disease. It is found that ventricular premature contraction should be performed 24h dynamic electrocardiogram, and quantitative and qualitative analysis of ventricular premature contraction to evaluate and guide prognosis. basic knowledge The proportion of sickness: 0.01% Susceptible people: the elderly Mode of infection: non-infectious Complications: sudden death
Cause
The cause of ventricular premature contraction in the elderly
(1) Causes of the disease
Ventricular arrhythmia in the elderly is more common in various organic heart diseases, such as coronary heart disease (acute myocardial infarction, unstable angina, ischemic cardiomyopathy) hypertension, cardiomyopathy, myocarditis, mitral valve prolapse Symptoms, due to myocardial inflammation, ischemia, hypoxia, stress load and excessive volume overload, cause myocardial mechanical, electrical and chemical stimulation to cause ventricular premature contraction, in addition, electrolyte imbalance, drug effects, carbon monoxide poisoning Digitalis poisoning, electric shock, etc. can cause premature ventricular contraction. Some elderly patients with ventricular arrhythmia are not necessarily caused by organic heart disease, nor can they have no structural heart disease.
(two) pathogenesis
1. Foldback mechanism
Reentry means that the impulse returns after activating a segment of myocardial tissue, and once again stimulates the segmental tissue. The formation of the reentry must have a reentry loop, one part of the conduction pathway has a one-way block, and the other part has a slow conduction rate of three conditions. The ventricular premature contraction associated with reentry is usually stable, and the interstitial interval is fixed. The ventricular arrhythmia is mostly caused by the reentry mechanism. It is divided into large reentry and micro-reentry. The reentry caused by ischemic myocardial tissue is a large reentry. The large scar tissue formed after necrosis has no electrical activity and conduction ability, but the complex around the scar tissue and the ischemic myocardium form a complex interweaving, resulting in slow conduction and refractory period, and the circular reentry that can be formed by the movement around the scar tissue. Ventricular arrhythmia, micro-return is the most common reentry in the heart chamber.
2. Trigger activity
The tiggered activity is generated by the posterior depolarization of the myocardial fibers. This post-depolarization can occur during repolarization (early post-depolarization), or after repolarization (late depolarization), after the early stage. The depolarization occurs during the repolarization process, and the late depolarization occurs after the completion of the repolarization or near completion.
(1) Early post-depolarization: After the myocardial action potential rises after the 0 pole, when the pole is not completely repolarized, that is, in the platform phase or the third phase, the membrane potential oscillation reaches the threshold potential, triggering another action potential is the early post-depletion. pole.
(2) Late depolarization: After the late depolarization occurs after the 3-pole repolarization of the action potential is completed, the maximum diastolic potential recovers close to the normal value, which is an oscillation of the membrane potential. When the amplitude reaches the threshold potential, The action potential is generated, that is, the so-called trigger activity, such as the membrane potential oscillation does not reach the threshold potential, which is manifested as the subthreshold posterior depolarization, and the trigger activity is terminated. It has been confirmed that the trigger activity is more and more occupied in the mechanism of ventricular arrhythmia. Important position.
3. Self-discipline enhancement
Self-discipline is determined by diastolic depolarization, rate, threshold potential and maximum diastolic potential, including normal self-regulation and abnormal self-discipline. There are two main reasons for the enhancement: one is the action phase 4-phase depolarization. Enhancement, in myocardial injury, hypoxia, digitalis overdose, hypokalemia and some drug effects can be caused; second, due to the decrease in resting membrane potential.
Prevention
Premature ventricular contraction prevention in the elderly
1. Active treatment of primary disease and etiological treatment.
2. Improve myocardial ischemia.
3. Be wary of RonT type ventricular premature contraction, should be high, as soon as possible.
Complication
Premature ventricular contraction complications in the elderly Complications
Common complications include ventricular tachycardia, ventricular fibrillation, and sudden cardiac death.
Symptom
Premature ventricular contraction symptoms in the elderly Common symptoms Arrhythmia ventricular ventricular fibrillation hypotension ventricular premature beats neck pulsation angina fainting tachycardia
Clinical manifestation
(1) Symptoms: In the elderly, premature ventricular contractions can have symptoms, asymptomatic and atypical symptoms.
1 typical symptoms: palpitations, heart "stolen" feeling and neck pulsation, frequent room two patients with two syndromes can occur syncope, because the early morning heart rate is insufficient, resulting in decreased cardiac output, early onset of room Excessive time can cause angina and hypotension.
2 Asymptomatic: The patient has no discomfort and is only found in physical examination or conventional electrocardiogram or 24h dynamic electrocardiogram.
3 atypical symptoms: the patient may have a sense of discomfort in the anterior region, which is obvious when quiet, and is asymptomatic after the activity.
(2) Signs:
1 auscultation can find pre-contraction after normal pulsation and subsequent interval, the reduction of ventricular filling during pre-systolic contraction leads to the first heart sound enhancement, the decrease of heart rate makes the second heart sound weaken or even disappear, and the radial artery palpation can be Long intervals are found, because the pulse of the pre-contraction itself is small and often cannot be touched.
2 signs of basic heart disease, such as rheumatic heart valve disease, the original heart murmur.
2. Classification
(1) Classification according to the form of pre-contraction:
1 Unilateral ventricular premature contraction: the pairing time of pre-systolic contraction is fixed and the QRS wave morphology is consistent, which is a single-source ventricular premature contraction.
2 ventricular parallel rhythm: the pairing time of pre-systolic contraction is not fixed and the QRS wave shape is consistent. The longest pairing interval and the shortest pairing interval are a common multiple, which may be ventricular parallel rhythm, and may have ventricular fusion wave.
3 multi-source ventricular premature contraction: the pairing time of pre-systolic contraction is inconsistent and the QRS waveform is inconsistent, and the QRS-T morphology has three or more shapes for multi-source ventricular premature contraction; In the case of two shapes, the two-source ventricular premature contraction is called, and the pairing interval of ventricular premature contraction is not fixed.
4 polymorphic ventricular premature contraction: the pairing time of pre-systolic contraction is fixed and the QRS wave shape is inconsistent, which is polymorphic ventricular premature contraction.
(2) Classification according to pairing time: RonT type ventricular premature contraction: this type of premature contraction occurs earlier, and its R wave falls on the T wave, because the ventricular premature contraction occurs in the vulnerable period of the ventricle, It is easy to cause ventricular tachycardia, ventricular fibrillation, and serious prognosis. It should be paid attention to. In addition, there are extra-early ventricular premature contraction, paired time-increasing ventricular premature contraction, and paired time-decreasing ventricular premature contraction. Pairing time alternates ventricular premature contraction.
Examine
Examination of ventricular premature contraction in the elderly
1. Blood test, blood potassium is low.
2. Typical ECG features of ventricular premature contraction:
Premature ventricular contraction is the early depolarization of ventricular muscle or Purkinje fiber. Usually, ventricular premature contraction can lead to T wave changes with wide QRS complex wave symmetry, and ventricular premature contraction is not reversed. Therefore, there is no obvious P wave, but the sinus rhythm is not interrupted, which is manifested as atrioventricular septum. For the same reason, ventricular premature contraction does not cause atrial and sinus node to be removed, so ventricular premature contraction appears completely compensated. Intermittent, mainly as follows:
1 The QRS complex with large deformity appearing in advance, the time limit is 0.12s, and the T wave direction is opposite to the main wave direction of the QRS complex;
2 There is no relevant P wave in front of the QRS complex;
3 Most compensation is intermittent;
4 If the ventricular premature contraction occurs in the high Hippo system, the QRS wave does not broaden, similar to the QRS wave in sinus rhythm;
5 Some patients may present with intermittent bundle branch block or pre-excitation syndrome pattern.
3. Dynamic ECG
The conventional 12-lead ECG is only recorded for 1 to 2 minutes, so the detection rate of ventricular premature contraction is low. At present, most clinical studies require at least 24h of dynamic electrocardiogram monitoring, and the detection of ventricular premature contraction is more accurate. Quantitative, many patients, ventricular premature contraction is only intermittent, the number of occurrences is not many, clinical manifestations of repeated palpitations, patients with syncope, through long-term ECG monitoring or telephone transmission of ECG, can be found and heart rhythm An abnormal relationship.
4. Exercise test
A series of physiological changes occurring in the body during exercise tests help to show ventricular premature contractions, especially complex and repetitive ventricular premature contractions are often induced during exercise. Therefore, exercise tests have become arrhythmia tests. The conventional method, but elderly patients with structural heart disease should be cautious.
Diagnosis
Diagnostic diagnosis of ventricular premature contraction in the elderly
diagnosis
According to the clinical manifestations, symptoms and signs and electrocardiogram findings for the diagnosis of ventricular premature contraction, especially for those who are asymptomatic but organic disease, repeated 24h dynamic electrocardiogram in time, help to find complex rooms Arrhythmia, which guides clinical treatment, determines prognosis, and takes preventive and therapeutic measures.
Differential diagnosis
Premature ventricular contractions should be differentiated from premature contraction with indoor differential conduction.
