Basic Electrocardiography Normal and abnormal ECG patterns - Part 5

Tất cả điều này có thể được quan sát trong hai PQRS phức hợp đầu tiên của chương trình này. QRS là một phức tạp tổng kết do depolarisation ban đầu thông qua con đường AV phụ kiện (đường cong) và phần còn lại của depolarisation qua đường AV bình thường (dòng không liên tục). | 66 Chapter 10 a p Normal activation Anomalous pathway Retrograde atrial activation Figure 52 Scheme of a heart with a right accessory AV pathway which leads to faster than normal AV conduction short PR and early activation of part of the ventricles and appearance of abnormal QRS morphology delta wave A . All this may be observed in the first two PQRS complexes of the scheme. The QRS is a summation complex due to initial depolarisation through the accessory AV pathway curved line and the rest of depolarisation through the normal AV pathway discontinuous line . The third p wave is premature atrial ectopic P that finds the accessory AV pathway in the refractory period. Due to this the impulse is only conducted by normal AV conduction discontinuous line in AV node usually with a longer than normal P R interval because the AV node is in a relative refractory period. This stimulus originates a normal QRS complex 1 and due to the fact that the accessory AV pathway is already out of the refractory period enters it from behind and is conducted retrogradely to the atria generating an evident P after the QRS complex in the case of reciprocal intranodal taquicardia the P is within the QRS complex or can be seen in its final part modifying the QRS morphology . At the same time the impulse re-enters and is conducted down to the ventricles via normal AV conduction B-2 .Due tothis macroreentry circuit the reciprocating taquicardia is maintained. The conduction in thiscnguitinretrocraOevia accessoryAV pathway curved iine andanterogrnrteaiarhqnormal uvcohdugtioc hiccautinuouslino . ohe RA rntiois smaller tcaorhed d rorio whicC styoical of the regiprogatiug taquigardia rhatinoolves an aggessory AV parhway. Ventricular pre-excitation 67 Figure 53 A 50-year-old patient with the Wolff-Parkinson-White syndromeof type IV who presents additionally a crisis of atrial fibrillation above and atrial flutter below that mimics ventricular taquicardia. The diagnosis of atrial fibrillation is .