Overview of Paroxysmal Supraventricular Tachycardia
Paroxysmal supraventricular tachycardia in the elderly is defined as a tachycardia originating in the atria or atrioventricular (AV) junction region, most of which are due to refractory excitation, while a few are caused by increased autonomic and triggered activity. Three or more consecutive supraventricular premature beats on the electrocardiogram are referred to as paroxysmal supraventricular tachycardia, which includes atrial and junctional tachycardia. Sometimes it is difficult to distinguish the two on the electrocardiogram and they are collectively referred to as paroxysmal supraventricular tachycardia.
Etiology
Coronary artery disease, myocardial infarction, hypoxemia, hypokalemia, preexcitation syndrome, heart failure, chronic obstructive pulmonary disease, other organic heart disease or with atrial enlargement, digitalis or other drug toxicity, infections, fever, hyperthyroidism, but also can be seen in the absence of any etiological factors, or because of the emotional excitement, excessive fatigue, smoking, drinking alcohol induced.
Symptoms
1. Fast heart rate, mostly 160-220 beats/minute, with regular rhythm.
2. Palpitations or a strong feeling of heartbeat in the chest.
3. Polyuria, sweating, dyspnea.
4. Long duration can lead to serious circulatory disorders, causing angina pectoris and ST-segment depression, dizziness, fainting, and even heart failure and shock.
5. Sudden onset and sudden cessation, in the cessation of the attack, due to the restoration of sinus rhythm interval is too long, occasionally occurring syncope.
6. Stimulation of the vagal nerve endings, can be suddenly aborted.
7. The heart sounds are absolutely regular and consistent, and the jugular vein does not show cannon waves. The pulse is rapid, and the blood pressure may fall.
Examination
1. Tachycardia caused by hyperthyroidism, T3 and T4 may be abnormal.
2. ECG shows more than 3 consecutive rapidly appearing QRS waves with frequency of 160-220 beats/min. R-R spacing is equal.
3. 24-hour heart rate changes on dynamic electrocardiogram are important for both qualitative and quantitative diagnosis of arrhythmia in patients.
Diagnosis
Diagnosis is made on the basis of symptoms and ECG findings.
1. Electrocardiogram shows more than 3 consecutive rapid QRS waves with a frequency of 160-220 beats per minute and equal R-R spacing.
2. 24-hour heart rate changes on dynamic electrocardiogram are important for qualitative and quantitative diagnosis of arrhythmia.
Differential diagnosis
Sinus tachycardia, atrial flutter, non-paroxysmal tachycardia.
Complications
Tachycardia with a frequency of more than 200 beats per minute can cause insufficient blood supply to the heart and brain organs, drop in blood pressure, fainting, convulsive seizures (Asperger’s syndrome), as well as angina pectoris, heart failure, and even sudden death.
Treatment
1. Stimulation of vagus nerve endings
It is mostly applied to young people, but not to the elderly. (1) ask the patient to hold his breath and then exhale forcefully; (2) stimulate the pharynx to cause nausea; (3) acupressure or massage of the carotid sinus, first try the right side of the 10s, such as ineffective, and then try the left side of the 10s, do not both sides at the same time, so as not to cause cerebral ischemia; (4) acupressure of the eyeballs, but also the first right and then the left, each time no more than 10s, can not be too strong, or else there is a risk of causing retinal detachment. Autonomic atrial tachycardia is ineffective in stimulating the vagus nerve.
2. Verapamil (isobaric) intravenous injection
It is preferred in patients who have not used a beta-blocker within 2 weeks.
3. Trichostatin C (sildenafil)
It should be preferred for PSVT with cardiac insufficiency, but is contraindicated in pre-excitation syndrome with QRS wave width.
4. Antihypertensive drugs
Suitable for PSVT with hypotension, but should not be used in the elderly.
5. Amiodarone plus glucose solution
Amiodarone 150mg added to 5% dextrose injection 30-50ml, intravenous injection. The effect is faster than Cetirizine C (Cetirizine) and slower than Verapamil (Isoboldine), but the side effects are very rare.
6. Overdrive or paired pacing
In case of ineffective treatment with various drugs, overdrive or paired pacing can be performed via esophagus or atria to abort the tachycardia attack.
7. Synchronized direct current pacing
In emergencies, such as acute heart failure, shock, etc., synchronized direct current resuscitation can be used.
8.Surgery
For PSVT with ineffective drug treatment or too frequent episodes, atrioventricular junction electrocautery can be performed, and a permanent cardiac pacemaker can be installed after the operation if necessary. For WPW with recalcitrant PSVT drug treatment is ineffective, can be used for bypass resection. In recent years, radiofrequency catheterization has been used to ablate and block the interatrial bypass tract, which is safe and effective with few complications.
Prognosis
If there is no obvious organic heart disease, occasional episodes of no more than a few minutes each time, and no obvious symptoms, the prognosis is good, and there is no need for special treatment. If there is organic heart disease, especially AMI complicating PSVT will easily lead to heart failure and shock, the prognosis is serious and should be actively controlled.
Prevention
First of all, we should pay attention to eliminate the factors that cause atrial pre-systole, such as mental mood fluctuations, work fatigue, smoking, drinking and so on. When frequent atrial pre-systole occurs, it should be actively treated.