Delayed arrhythmias

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 .


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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.


  • 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.


  • 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.


  • 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.


  • Frequent in young people , who suffer from attacks of ectopic tachycardia.
  • Ebstein’s anomalies.
  • In some cases of endocardial fibroelastosis.


  • 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.


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