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Lecture notes, cheat sheets
Internal illnesses. Arrhythmias due to impaired impulse formation (lecture notes)
Directory / Lecture notes, cheat sheets Table of contents (expand) LECTURE No. 19. Arrhythmias due to impaired impulse formation 1. Sinus tachycardia Sinus tachycardia - an increase in cardiac activity at rest more than 90 beats per minute with the correct rhythm. Etiology. It occurs due to an increase in the tone of the sympathetic nervous system (physical activity, fever, intoxication, infections, etc.). Tachycardias are physiological (with physical exertion, emotions, fear, getting up quickly) and neurogenic (with neuroses). Tachycardia can be observed in diseases of the cardiovascular system, with drug and toxic effects, with acute and chronic infections and anemia. Clinic. Complaints are determined by the underlying disease. i tone is enhanced, ii tone is more often weakened, pendulum rhythm and embryocardia are possible. On the ECG, the heart rate is more than 90 beats per minute, the duration of the RR interval is less than 0,60 s, the rhythm is correct. Treatment. The intake of tea, coffee, alcohol, spicy food is limited. In the functional form, psychotropic and sedatives, tranquilizers, antipsychotics (meprobamate, diazepam), according to indications, β-blockers (atenolol, egilok in doses that do not reduce the number of heartbeats below 60 beats per minute) are used. In the cardiac form with heart failure, cardiac glycosides and saluretics are used; treatment of the underlying disease. 2. Sinus bradycardia Sinus bradycardia is a decrease in heart rate below 60, but not less than 40 per minute. Etiology. The reasons are: an increase in the tone of the vagus nerve, a decrease in the tone of the sympathetic nerve, a direct effect on the cells of the sinus node (hypoxemia, infection). Bradycardias are functional (vagal) and organic (such as the defeat of the sinus node). Clinic. The clinic is manifested by palpitations, fainting. On the ECG, the RR interval is more than 1 s, the rhythm is sinus. Treatment. With functional bradycardia, treatment is not carried out. With organic bradycardia with a heart rate of less than 40 beats per minute and a tendency to faint, atropine is administered 0,5-1,0 mg intravenously every 3 hours (up to 2 mg) or 0,5-1,0 mg 3-4 times inside, isadrin 1,0-2,0 mg in 500 ml of a 5% glucose solution intravenously, alupent 5-10 mg in 500 ml of physiological saline intravenously or orally, 20 mg 4-8 times a day. 3. Sinus arrhythmia Sinus arrhythmia - alternating periods of increased and slower heart rate due to uneven generation of an impulse in the sinus node. Etiology. The reasons are fluctuations in the tone of the vagus during breathing, organic pathology of the heart (CHD, rheumatic heart disease, myocarditis, digitalis intoxication). Clinic. Arrhythmias are respiratory (physiological) and actually sinus arrhythmias. On the ECG, there is an irregular sinus rhythm with a difference between the longest and shortest RR intervals of 0,16 s or more. Treatment. Treatment consists in the treatment of the underlying disease. 4. Sick sinus syndrome Sick sinus syndrome - paroxysms of supraventricular tachycardia (or atrial fibrillation) followed by a long period of severe sinus bradycardia. Described by B. Lown in 1965. Etiology. The causes are organic heart damage (acute period of myocardial infarction, atherosclerosis, myocarditis, cardiopathy, digitalis intoxication, antiarrhythmic drugs). Clinic. Possible sinus bradyarrhythmias, loss of individual sinus complexes with prolonged asystole and subsequent restoration of the rhythm by sinus complexes or due to impulses from the underlying sections (popping complexes). Depending on the duration of the periods of asystole, there may be dizziness, fainting, Morgagni-Adams-Stokes seizures. Treatment. With mild bradycardia and passive heterotopic arrhythmias, treatment is not carried out. With attacks of tachyarrhythmias and paroxysmal tachycardia, antiarrhythmic drugs are indicated: aymalin 50 mg intravenously or intramuscularly, novocainamide intravenously or intramuscularly 5 ml of a 10% solution, isoptin intravenously 5-10 mg, inderal (obzidan) 5 mg intravenously carefully, strophanthin 0,5 ml of 0,05% solution intravenously per 20 ml of glucose or isotonic solution. With repeated attacks of asystole, electrical stimulation of the heart is performed. 5. Rhythm of the atrioventricular connection The rhythm of the atrioventricular connection is the rhythm in which the area of transition of the atrioventricular node into the bundle of His or the trunk of the bundle of His before it branches into branches becomes the pacemaker. Etiology. The causes are vagotonia (with a healthy heart), medicinal effects and metabolic disorders (digitis intoxication, quinidine, morphine, hyperkalemia, acidosis, hypoxia), organic heart disease (IHD, hypertension, heart defects, myocarditis, rheumatic heart disease, shock). Clinic. Clinical manifestations are characterized by bradycardia with the correct rhythm of 40-60 beats per minute, enhanced tone I, increased pulsation of the jugular veins. On the ECG, there is a negative P wave, an unchanged QRST complex. Treatment. The underlying disease is being treated. Atropine, isadrin, alupent are used. Antiarrhythmic drugs are contraindicated. With hyperkalemia and acidosis, drip administration of sodium bicarbonate and glucose with insulin is carried out. With complete atrioventricular blockade, an artificial pacemaker is implanted. 6. Idioventricular rhythm Idioventricular rhythm - the pacemaker of the heart becomes the center of the third order with a rare rate of contraction - 20-30 beats per minute. Etiology. The reason is severe myocardial damage. On the ECG - altered QRST complexes (as in ventricular extrasystole), negative P waves (coincide with the ventricular complex). Treatment. The underlying disease is being treated. 7. Extrasystoles Extrasystoles - contraction of the whole heart or any of its departments under the influence of a premature impulse from the cells of the conduction system of the atria and ventricles. Etiology. Causes: re-entry of the sinus impulse (local blockade), increased automatism outside the sinus node. Extrasystoles are of functional genesis (extracardial), organic genesis (for example, ischemic heart disease, heart defects, myocardial damage), toxic genesis (digitis intoxication, adrenaline, nicotine, caffeine, ether, carbon monoxide, etc.), mechanical genesis (catheterization, operations on heart). Classification. Classification of ventricular extrasystoles (according to Laun). I degree - single rare monotopic extrasystoles no more than 60 in 1 hour. II degree - frequent monotopic extrasystoles more than 5 in 1 min. III degree - frequent polytopic polymorphic extrasystoles. IV degree - A-group (paired), B-3 and more in a row. V degree - early extrasystoles of type P to T. Treatment. It consists in the treatment of the underlying disease. A diet, regimen, hydrotherapy should be used. Sedative drugs, antiarrhythmic treatment (if necessary) are prescribed. With the threat of ventricular fibrillation, lidocaine or novocainamide is indicated intravenously. 8. Paroxysmal tachycardia Paroxysmal tachycardia is a sudden increase in heart rate as a result of impulses emanating from a focus located outside the sinus node. Etiology. The causes are strong emotions, nervous tension, overwork, excessive consumption of nicotine, coffee, tea, alcohol, thyrotoxicosis, reflex influences (in diseases of the gastrointestinal tract), WPW and CLC syndrome, myocardial diseases (ischemic heart disease, myocarditis), hypertension , mitral stenosis, digitalis intoxication, hypokalemia. Treatment. Supraventricular paroxysmal tachycardia is stopped by massage of the carotid sinus zone, using the Valsalva test (pressure on the eyeballs). Inside, 40 mg of propranolol is prescribed, slow intravenous administration of 2-4 ml of a 0,25% solution of isoptin, in the absence of hypotension, 5-10 ml of a 10% solution of novocainamide (preferably with preliminary administration of mezaton or norepinephrine), slow administration of 0,25 -0,5 ml of a 0,05% solution of strophanthin, in the absence of effect - defibrillation. Relief of an attack of ventricular paroxysmal tachycardia is carried out using electrical impulse therapy, intravenous injection of lidocaine, 5,0-20,0 ml of a 1% solution, then drip at a dose of 500 mg in 500 ml of a 5% glucose solution 3-4 times a day. 1st and 2nd days after rhythm recovery. In non-severe conditions, novocainamide is administered orally 0,75 g and then 0,25 g every 3 hours or intravenously drip 5,0-10,0 ml of a 10% solution in saline or 5% glucose solution (with a decrease in blood pressure in combination with norepinephrine drip). Aymalin, β-blockers; cardiac glycosides are contraindicated. 9. Atrial fibrillation (atrial fibrillation) Atrial fibrillation (atrial fibrillation) - complete loss of atrial systoles. Up to 350-600 pulses circulate in the myocardium. The rhythm of ventricular contractions is wrong. Etiology. The causes are organic myocardial damage (IHD, acute myocardial infarction, mitral defects, cardiopathy, myocarditis), thyrotoxicosis. Pathogenesis. The mechanism of excitation re-entry is micro reentry, stopping the sinus node. Classification. Atrial fibrillation is paroxysmal, permanent form: tachysystolic (more than 90 beats per minute), normosystolic (60-90 beats per minute), bradysystolic (less than 60 beats per minute). Clinic. There is general weakness, palpitations, shortness of breath. Auscultation determines the arrhythmia of tones, changes in the volume of tones; pulse deficit. There are no P waves on the ECG, ventricular complexes are irregular, the isoelectric line is wavy. Complications. Thromboembolism may develop. Treatment. To stop the attack, sedatives are used, propranolol inside; while maintaining the attack - 4-8 g of potassium chloride diluted in water, intravenous administration of 5,0-10,0 ml of a 10% solution of novocainamide. In the presence of heart failure in elderly patients, strophanthin is used. In persistent cases of atrial fibrillation, quinidine and electrical impulse therapy are used. To prevent seizures, quinidine (0,2 g 2-4 times a day) with propranolol (10-40 mg 2-3 times a day) or delagil with propranolol are used. With a constant form of atrial fibrillation, cardiac glycosides are prescribed, possibly in combination with β-blockers. Defibrillation is performed with a recent (up to a year) atrial fibrillation. Contraindications to defibrillation are prolonged arrhythmias, a history of paroxysm, an active inflammatory process, cardiomegaly, severe circulatory failure, and a history of thromboembolism. 10. Atrial flutter Atrial flutter - rapid, superficial, but the correct rhythm of atrial contraction with a frequency of 200-400 per minute, resulting from the presence of a pathological focus of excitation in the atria. The frequency of contractions of the ventricles is much less. Etiology. The causes are organic heart disease (valvular disease, coronary artery disease, thyrotoxicosis, rheumatic heart disease, myocarditis, intoxication). Clinic. Forms: paroxysmal, constant. On the ECG, atrial waves in the form of saw teeth. Treatment. It is carried out similarly to the treatment of atrial fibrillation (atrial fibrillation). 11. Ventricular fibrillation (ventricular fibrillation) Ventricular fibrillation (ventricular fibrillation) - uncoordinated, asynchronous contractions of individual muscle fibers of the ventricles. Etiology. The causes are organic heart disease (IHD, acute myocardial infarction, primary circulatory arrest, aortic stenosis, myocarditis), heart failure, postoperative period, hypothermia, WPW syndrome, intoxication, electrical injury. Pathogenesis. Weak, erratic contractions of the muscle fibers of the ventricles are noted, the aortic semilunar valves do not open. The stroke volume of the heart drops to zero, blood flow to the organs stops. Death occurs within 4-8 minutes. Clinic. Clinical manifestations are characterized by loss of consciousness, pallor, cold sweat. Arterial pressure drops to zero, heart sounds are not heard, there is no breathing, the pupils are dilated. On the ECG - large- or small-amplitude random waves follow without intervals; The onset of death. stage i - reversible state for no more than 8 minutes (clinical death), stage II - biological death. Resuscitation measures. The patient must be laid on a hard bed, tilt his head back, fix the lower jaw and tongue, clean the oral cavity (dentures). Carrying out artificial ventilation mouth to mouth or mouth to nose and indirect heart massage in the ratio of 2 inhalations and 15 massages (1 resuscitator works) or 1 inhalation and 4 massages (2 resuscitators work). If it is ineffective, three-time defibrillation of 200 J, 300 J, 360 J is performed. If there is no effect (small-wave fibrillation on the ECG or asystole), 1 ml of a 0,1% solution of adrenaline is injected intravenously or 2 ml endotracheally, after the introduction, defibrillation is repeated. With successful resuscitation, intravenous administration of 80-120 mg of lidocaine is carried out under the control of acid-base balance, with acidosis - the introduction of sodium bicarbonate. With unsuccessful resuscitation, repeated administration of adrenaline intravenously by bolus or intratracheal is indicated at the same dosage every 3-5 minutes, followed by defibrillation at 360 J. CPR must be carried out within 40 minutes. After resuscitation, lidocaine is administered intramuscularly for 2-3 days every 6-8 hours; over the next 8-18 months, β-blockers are prescribed. Author: Myshkina A.A. << Back: Restrictive cardiomyopathy >> Forward: Arrhythmias due to impaired conduction of impulses
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