■不适当的窦性心动过速(IST)的特征是连续的症状,IST的病因不精确。IST引起的自主神经功能障碍是众所周知的,但是据我们所知,IST引起的房室传导阻滞没有报道。
■一名67岁女性,有4天的随机间歇性呼吸困难史,胸闷,心悸,头晕,在家庭监测设备上记录心率为每分钟30次(BPM)。最初的心电图(ECG)显示窦性心律,间歇性MobitzI型二度房室传导阻滞,连续的心脏监测显示Wenckebach现象全天频繁发作,窦性心率为100-120BPM.超声心动图显示无明显结构异常。病人在服用比索洛尔,因此,怀疑Wenckebach可能是由于这个原因,所以停止了。然而,停止比索洛尔48小时后对节律没有明显影响,导致怀疑IST诱导的MobitzI型二级房室传导阻滞;因此决定每天两次引入伊伐布雷定2.5mg。伊伐布雷定24小时后,患者仍处于窦性心律,心脏监护仪上未出现Wenckebach现象,这一发现随后被24小时Holter监测证实。在最近的诊所随访中,病人仍然没有症状,心电图显示窦性心律的生理速率。
■MobitzI型二度房室传导阻滞通常是由于房室结水平的可逆传导阻滞,因此发生故障的房室结细胞倾向于逐渐疲劳,直到它们无法传导冲动。在迷走神经张力增加和自主神经功能障碍的情况下,Wenckebach事件将增加。因此,伊伐布雷定在窦房(SA)结内的选择性脉冲传导,以减少IST/自主神经失调引起的MobitzI型AV患者向房室结的搏动传导,将减少Wenckebach的发生。
UNASSIGNED: Inappropriate sinus tachycardia (IST) is characterized by a continuum of symptoms, and the aetiology of IST is imprecise. IST-induced autonomic dysfunction is well known, but IST-induced atrio-ventricular block is not reported to our knowledge.
UNASSIGNED: A 67-year-old female presented with a 4-day history of random intermittent difficulty in breathing, chest tightness, palpitations, and dizziness, with a recorded heart rate of 30 beats per minute (BPM) on home monitoring equipment. The initial electrocardiogram (ECG) demonstrated sinus rhythm with intermittent Mobitz type I second degree atrio-ventricular (AV) block, with continuous cardiac monitoring demonstrating frequent episodes of Wenckebach phenomenon throughout the day, with a sinus rate of 100-120 BPM. Echocardiogram showed no significant structural abnormalities. The patient was on bisoprolol, and hence, it was suspected Wenckebach may be due to that and so stopped. However, there was no tangible effect on rhythm 48 hours after stopping bisoprolol, leading to a suspicion of IST-induced Mobitz type I second degree AV block; and so decided to introduce ivabradine 2.5 mg twice daily. After 24 hours of Ivabradine, the patient remained in sinus rhythm with no documented episodes of Wenckebach phenomenon on cardiac monitor, a finding subsequently confirmed by 24-hour Holter monitoring. During a recent follow-up visit in clinic, the patient remained symptom-free, with an ECG demonstrating sinus rhythm at a physiological rate.
UNASSIGNED: Mobitz type I second degree AV block is usually due to reversible conduction block at the level of the AV node whereby malfunctioning AV nodal cells tend to progressively fatigue until they fail to conduct an impulse. Under conditions of increased vagal tone and autonomic dysfunction, Wenckebach occurrence will be increased. Thus, selective impulse conduction within the sinoatrial (SA) node by ivabradine to reduce beat conduction to the AV node in patients with IST/dysautonomia-induced Mobitz type I AV will reduce the occurrence of Wenckebach.