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، جلد ۷، شماره ۲، صفحات ۴۲-۴۳
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| عنوان فارسی |
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| چکیده فارسی مقاله |
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| کلیدواژههای فارسی مقاله |
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| عنوان انگلیسی |
WHAT IS THE MECHANISM OF GROUP BEATING? |
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| چکیده انگلیسی مقاله |
An eighty-year-old male was referred to our center because of dizziness and palpitation for the previous two weeks. He had no history of syncope and the drug history was unremarkable. Figure 1 shows the resting ECG, interpreted as complete heart block by the referring physician. A transthoracic echocardiography was done and showed a left ventricular ejection fraction of 35% and a severely calcified mitral valve with an estimated mitral valve orifice area of 1.4 cm2.Group beating was observed on the ECG, and a closer look at the ECG suggested the diagnosis of sino-atrial node Wenckebach (SANW) exit block. Premature atrial beat trigeminy could have also explained the group beating of the P-waves. However, the similarity of the P-wave morphologies and the confirmation of the diagnosis of sick sinus syndrome by electrophysiology study made this diagnosis unlikely and suggested the SANW as the cause of P-wave group beating.Apparently there seems to be a conduction defect at the atrio-ventricular nodal (AVN) level. The PR interval of the first conducted P-wave is longer (first black arrow) than the subsequent PR interval, which is then followed by a non-conducted P-wave. Nevertheless, a close look at the ECG reveals the real underlying mechanism of apparent AV block. Due to SANW, the PP intervals gradually shorten and the third P-wave is blocked as it encounters the physiologic refractory period of the AVN. After the third P-wave, there is a pause due to SA exit block (4th P-wave, blocked at the SAN level) followed by a conducted P-wave with a long PR interval. This phenomenon could be best explained by phase-four (bradycardia-dependent) conduction blocks.Electrocardiographic changes in this patient could also be explained by the effect of cyclelength duration on infra-Hissian conduction. Thus, PR interval prolongation can be due to His-Purkinje refractoriness in the longer cycle length. The shorter PR interval in the next beat may be due to a decrease in the HV interval in the shorter cycle length. In this scenario, the last P-wave would be blocked in the AV node. |
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| کلیدواژههای انگلیسی مقاله |
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| نویسندگان مقاله |
M. SHOJAEIFARD |
ARASH. ARIA |
DEPARTMENT OF PACEMAKER AND ELECTROPHYSIOLOGY, RAJAIE CARDIOVASCULAR MEDICAL AND RESEARCH CENTER, MELLAT PARK, VALI-ASR AVENUE, TEHRAN 1996911151, IRAN
M. HAGHJOU |
M. SADR AMELI |
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| نشانی اینترنتی |
http://journal.iha.org.ir/article_84024_7eceeec0081d6d283bfb66e0447cbdb4.pdf |
| فایل مقاله |
اشکال در دسترسی به فایل - ./files/site1/rds_journals/162/article-162-1424179.pdf |
| کد مقاله (doi) |
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| زبان مقاله منتشر شده |
en |
| موضوعات مقاله منتشر شده |
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