Arrhythmia caused by dysfunction of the excitability of the heart

To arrhythmias of the heart, caused by dysfunction of the excitability of the heart, are premature beats and paroxysmal tachycardia.
Arrythmia - the most commonly observed the violation of a heart rhythm, consisting in premature reduction in our hearts-or some of its parts caused by pathological irritation. After extrasystoles should usually elongated compensatory pause. Extrasystoles center of pathological irritation divided into sinoatrial, atrial, atrioventricular and ventricular (Fig. 8-15).
The starting point of the pathological irritation causing premature reduction, and determines the amount of subsequent compensatory pause. The duration of full compensatory pause with beats and shorter cycle preceding normal reduction is equal to the duration of two standard abbreviations. Duration shortened compensatory pause less.
Ventricular extrasystoles are accompanied in most cases, the full compensatory pause, and atrial and atrioventricular is usually shortened. Pause after sinus PVCs equal pause normal contractions. While long diastole, when extrasystoles occur shortly after the normal cuts, sometimes they are located between two normal contractions - insertion interpolated extrasystoles (Fig. 13).
There are two forms arrythmia - arrythmia with persistent, not changing ekstrasystolichniy interval (distance extrasystoles from normal reduction) and with the changing ekstrasystolichniy interval.
Extrasystoles different way, combined with the normal contractions of the heart. When properly interleaved (algoritmy) beats can follow every normal reduction (bigeminiya), for every two cuts (FREQ), for every three cuts (quadrigemina), and so on, Sometimes for normal contraction follows a group of two, three PVCs and more.
Clinical observations show that, on the one hand, rhythmic forms arrythmia (allaritmin) usually unstable and can under the influence of certain factors to pass one another or become invalid. A seemingly incorrect alternation of extrasystoles sometimes you can catch certain the correct combination.
When analyzing the number of cases arrythmia we can assume that the simultaneous existence of two sources of origin of the pulse: normal (nontobeko) and pathological (heterotopic) - parasystole [Kaufman, Rotberger (R. Kaufmann, S. Rothberger)].
The mechanism of occurrence of arrythmia and its dependence on violations of excitability of the heart is not quite clear. Experimental data and clinical observations suggest that the emergence of extrasystoles, you must have the heart of a pathological focus, which is the source of a pathological impulse that causes premature contraction of the heart. However, a pathological focus at the heart can remain hidden and does not manifest, if the power of emerging irritation insufficient to cause the beats.
In appearance arrythmia great importance is the change of the nervous system that causes the violation of the nervous regulation of cardiac activity, with predominance of either sympathetic or parasympathetic nervous system. In the pathogenesis arrythmia matters and the extent of myocardial excitability. Arrythmia can be caused by various factors: infections, intoxications, mental, climatic, atmospheric influences, reflexes of internal organs, and so on, Extrasystoles often seen in various diseases of the cardiovascular system. Often extrasystoles occur without any visible indication of the defeat of the cardiovascular system.
Ekstrasystolichniy reduction due to the small blood flow to the heart and not enough recovered contractility causes reduced systolic volume. Sometimes the abbreviation is so weak that he could not overcome resistance in the aorta and the pulmonary artery is a fruitless reduction. The subsequent reduction strengthened and causes increased systolic volume. In severe myocardial lesions are observed extrasystoles, coming from different points - politopnaya extrasystoles.
The clinical picture. In most cases, each beats felt sick or as cardiac arrest (compensatory pause), or as a shot in the chest and throat (further strengthened contraction of the heart). Patients with arrhythmia can be divided into two are not always differentiated main types. Patients first Tina (uredenim pulse, low blood pressure, often with visokosnaya aperture and recumbent heart, sometimes with obesity) complain about the faults that appear alone, " extrasystoles peace; the patients of the second type (usually thin, with increased heart rate) - on extrasystoles, appearing on exertion,- extrasystoles voltage.
Feeling the pulse can catch premature, weaker wave. Sometimes when early extrasystoles reduction weak, does not reach the periphery and with the feeling of the heart rate, you can get a sense of loss of heart contractions. Auscultation during ekstrasystolichniy reduction heard two premature tone. When barren abbreviations instead of two premature tones are heard one; the second tone caused by the closure of the semilunar valves, falls.
The first tone extrasystoles with ventricular extrasystoles mostly weaker than normal tone reduction. When atrial and AV extrasystoles first tone can be both strengthened and weakened (L. I. Fogelson).
On roentgenogram ekstrasystolichniy reduction corresponds reduced narrow spike. The distance between ekstrasystolichniy tooth and subsequent normal reduction increased, and this prong wider than normal teeth and greater amplitude.
Electrocardiographic picture when PVC is mainly determined by the initial point extrasystoles. When sinus extrasystoles form of atrial and ventricular complexes normal.

arrythmia
Fig. 8. Extrasystole. Atrial extrasystoles: 1 - normal passage of excitation in the ventricles; 2 - with changed by the passage of excitation in the ventricles.
atrial extrasystoles
Fig. 9. Extrasystole. Atrial extrasystoles (bigeminiya)

For atrial premature beats (Fig. 8, 9) is characterized by the presence of atrial teeth R. Form, and P wave changed and depends on the location of the source of a pathological impulse in the Atria. Ventricular complex for the most part not changed, except for cases of violation of the passage of excitation in the ventricles (Fig. 8).
On FCG the oscillation amplitude of the first tone extrasystoles can be reduced or increased (Fig. 9).
When the AV PVCs, and P wave is always negative, as the atrial excitation occurs retrograde way. Depending on localization of the source of the pulse wave R or precedes the QRS complex or merges with it, or is localized between the micro and the T wave (Fig. 10). Ventricular complex is usually not changed.


Fig. 10. Extrasystole. Of atrioventricular beats coming from the bottom of the atrioventricular node.

Fig. 11. Extrasystole. Beats coming from the left ventricle (standard ECG, chest and unipolar from limb-lead).


For ventricular extrasystoles (Fig. 11-15) was characterized by the absence, and P wave, broadened and serrated QRS complex, no segment RS - T and the T wave, usually aimed in the opposite direction of the greatest wave of QRS complex.
When extrasystoles, coming from the right ventricle, the largest wave of QRS complex is directed upwards in the first abduction, unipolar lead from the right leg and right positions chest leads and down in III, unipolar lead from the left hand and the left-wing positions chest leads (Fig. 12, 14).
When extrasystoles. outgoing from the left ventricle, the largest wave of QRS complex facing down in the first abduction, unipolar lead from the left hand and left positions of thoracic and leads up to the third lead, unipolar lead from the right leg and right positions chest leads (Fig. 11, 13, 15).
The shape of teeth, following the extrasystoles reduction, mainly teeth P and T, sometimes changed. This is caused, apparently, by the defeat of wiring systems and the contractile myocardium.


Fig. 12. Extrasystole. Beats coming from the right ventricle (standard ECG, chest and unipolar from limb-lead).

Fig. 13. Extrasystole. Interpolated beats coming from the left ventricle. Beats does not cause the disclosure of semilunar valves - barren reduction. SFG brachial artery.

Fig. 14. Extrasystole. Extrasystoles come from the right ventricle. Bigeminiya simulating alternating pulse. SFG brachial artery.

Fig. 15. Extrasystole. Group extrasystoles . For every two normal abbreviations should a group of three PVCs, outgoing from the left ventricle.

If interpolated extrasystoles interval P - Q subsequent normal reducing often increased as a function of the conductivity does not have time to fully recover (Fig. 13).
On FCG with ventricular extrasystoles atrial oscillations first tone is missing; the amplitude of ventricular oscillations first tone largely reduced. The amplitude of the first tone when atrial and AV extrasystoles different depending on the ratio of atrial and ventricular contractions.
Diagnosis arrythmia usually easy and is set on the basis of data auscultation and feeling the pulse, and topical diagnostics using ECG.
Evaluation of ability to work when PVC is determined by the value of a pathological focus, which is the source arrythmia; localization of pathologic focus; the degree of impact on the heart of the parasympathetic and sympathetic departments of vegetative nervous system. Atrial and atrio-ventricular extrasystoles are often the precursor to more serious arrhythmias: paroxysmal tachycardia and flicker atrium.
The employment forecast significantly less favorable for outgoing from various points of the heart (polytopic) extrasystoles, than when coming from a single point. When extrasystoles of peace, when the heart is in good condition, the patient can perform work, even related to physical stress. When extrasystoles voltage significant exercise worsens the condition of the patient.
Treatment. Assign funds reduce the excitability of the pathological focus: quinidine at doses of 0.2-0.3 g 3-5 times a day, and then oseltamivir 0.1-0.2 g 2-3 times a day; novokainamid (mainly with ventricular extrasystoles) 0.5-1 g 4-6 times a day inside or intramuscularly. A number of authors recommended the use of potassium salts (potassium chloride 1-2 g 3 times a day) usually in combination with quinidine or procainamide.
When extrasystoles rest is recommended to combine the use of quinidine or procainamide hydrochloride with atropine (0.5 mg atropine 2-3 times a day).
Return extrasystoles are rare form of rhythm disturbances, sometimes observed when the atrio-ventricular rhythm, when the impulse comes from the bottom of the site and ventricular contraction precedes atrial. In these cases because atrial contraction again should ventricular. Occurs a group of two ventricular contractions and inserted between them atrial contractions.
The clinical picture is characterized by the traits peculiar to the clinical picture at the atrioventricular rhythm coming from the bottom of the site. ECG normal form ventricular complex is adjacent to the complex, due to atrioventricular rhythm.
Diagnosis is based on the data of ECG examination.