Delayed arrhythmias . Cardiac arrhythmias are often a reflection of an underlying disease process that is not necessarily limited to the heart . Therefore, it is necessary to practice a careful evaluation of the medical history and physical examination in patients in search of a pre-existing disease .
Summary
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- 1 Atrioventricular blocks
- 2 Classification
- 1 Second degree atrioventricular block
- 2 Mobitz II type second degree atrioventricular block
- 3 Electrocardiographic criteria
- 4 Semi-diagnosis
- 5 Treatment
- 6 Sources
Atrioventricular blocks
- In this arrhythmia, the conduction disorder is that the passage of the excitation wave is difficult or impeded at the level of the atrioventricular node.
Classification
- They are classified into three types: first, second and third grades.
- First degree atrioventricular block.
- Electrocardiographic criteria:
- PR interval with a duration of 0.20 s or greater.
Semi-diagnosis
- Functional causes: in athletes.
- Organic causes: degenerative affections of the myocardium, acute joint rheumatism, diphtheria.
- Toxic causes: Digitalis intoxication.
Second degree atrioventricular block
- They have been classified into two types: Mobitz I and Mobitz II.
- Mobitz I second-degree atrioventricular block.
- Electrocardiographic criteria.
- Constant PR interval, before a P wave is unexpectedly driven, that is, a P wave that is not followed by a QRS complex.
- After a P wave is not driven, the next PR interval is shorter, equal to the first in the previous cycle.
Mobitz II type second degree atrioventricular block
- Electrocardiographic criteria:
- Constant PR intervals, before no driving, unexpectedly a P wave
- Third-degree (complete) atrioventricular block.
Electrocardiographic criteria
- The PP distances are equal to each other and different from the QRS complexes, which in turn keep the same distance from each other.
- The atrial rate is higher, approximately twice the ventricular rate that varies between 32 and 55 / min and depends on the site of the distal subsidiary pacemaker, the lower the rate is lower.
- There is, therefore, no PR interval, that is, a relationship between the P waves and the QRS complex, the P wave can fall before, after or coincide with the QRS complex, and give the impression when observing the tracing of a very PR variable.
- The morphology of the QRS complex will vary with the site of implantation of the ectopic focus.
Semi-diagnosis
- Diffuse degenerative processes of the myocardium.
- Accelerated arrhythmias:
- Wolff-Parkinson-White syndrome.
- Electrocardiographic criteria:
- Short PR, less than 0.12 s in duration, practically no PR, showing the P wave followed by the QRS complex.
- QRS complexes of prolonged duration, 0.12 s or greater: presence of delta wave: slowness or rounded notch at the beginning of QRS.
Semi-diagnosis
- Frequent in young people , who suffer from attacks of ectopic tachycardia.
- Ebstein’s anomalies.
- In some cases of endocardial fibroelastosis.
Treatment
- Isolated supraventricular extrasystole does not warrant treatment. But if they are frequent and cause anxiety in the patient, beta-blockers (propanolol) or quinidine are indicated. If there are underlying causes (hypocalcemia, coronary heart disease, excess tobacco and caffeine) they should be corrected.
- Ventricular extrasystoles warrant treatment if their frequency exceeds 10 per minute, when they originate in different foci or when there is a danger of triggering a more serious arrhythmia. If there is a known cause, such as in digitalis poisoning, the drug and administer potassium to correct hypokalemia.
- Ventricular extrasystoles present in the acute phase of myocardial infarction are rapidly treated with the following scheme: 2% lidocaine without epinephrine. 2-3 ml are prescribed intravenously directly; maintenance drip is continued (10-20 ml in 500 ml of 5% dextrose) at a rate determined by the patient’s response.
- If the arrhythmia continues, procainamide can be used in doses of 50-100 mg every 10 minutes until the arrhythmia is controlled without exceeding the maximum dose of 800 mg. The maintenance dose is 250 mg every 4 hours.
- Diphenylhydantoin is usually useful when prolonged treatment is needed, in doses of 200-400 mg per day. Ventricular extrasystoles detected in hypertrophic cardiomyopathy and mitral valve prolapse are controlled with propanol at doses of 80-160 mg per day.
