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The cardiac system: Physiology and principles of care
Published in Judy Bothamley, Maureen Boyle, Medical Conditions Affecting Pregnancy and Childbirth, 2020
The SA node acts as the pacemaker for the heart. The other zones – the AV node, the bundle of His and Purkinje fibres – are latent pacemakers that can take over, although at a lower rate, should the SA node fail. Complete heart block occurs when the conducting tissue between the atria and ventricles is damaged and the ventricles then beat at only 30 beats per minute. An artificial pacemaker is required to restore the normal heart rate. Occasionally an area of the heart, such as the Purkinje fibres, becomes overexcited and depolarises at a more rapid rate. This is known as ectopic beats. If the ectopic focus continues to charge rapidly the heart rate goes up. This can be associated with heart disease but more frequently occurs in response to anxiety, excess caffeine or smoking and alcohol. Ectopic beats are common in pregnancy (Adamson, et al., 2007). Pregnant women may experience skipped beats, momentary pressure in the neck or chest or extra beats suggestive of arrhythmias. This is usually due to increased sympathetic nervous system activity. Occasionally cardiac problems may present during pregnancy so investigation is recommended (Blackburn, 2007).
Ventricular rhythms
Published in Andrew R Houghton, Making Sense of the ECG, 2019
Accelerated idioventricular rhythm is essentially a slow form of VT, with a heart rate of less than 120 beats/min (Figure 8.6). It occurs when an ectopic focus within the ventricles starts firing with a rate just higher than that of the sinoatrial node – this ventricular focus then takes over the cardiac rhythm.
Adaptation to Stress and its Cardioprotective Effect in Stress, Ischemic, and Reperfusion Damage
Published in Felix Z. Meerson, Alexander V. Galkin, Adaptive Protection of The Heart: Protecting Against Stress and Ischemic Damage, 2019
Felix Z. Meerson, Alexander V. Galkin
A priori, this complex of alterations can be supposed to constitute the basis of irregular conduction of excitation and to be thus involved in formation of reentry and cardiac fibrillation upon a premature impulse from an ectopic focus. In our experiments such an impulse was created by premature electric stimulation of the apex cordis, and the current necessary to cause reversible fibrillation in animals with postinfarction cardiosclerosis was half that in the control. The above interpretation is in complete accord with the results of clinicophysiological studies where the surviving cells of the border zone in postinfarction cardiosclerosis in humans were identified as the origin of ventricular tachycardia in chronic IHD patients.
Atrial fibrillation is an independent risk factor for new-onset myocardial infarction: a prospective study
Published in Acta Cardiologica, 2023
Jianmei Wu, Qiqi Hou, Quanle Han, Ruiying Mao, Bocheng Yue, Jing Yu, Shuohua Chen, Shouling Wu, Kangbo Li
Secondly, it is well known that focal ectopic activity initiates all types of AF (i.e. paroxysmal AF, persistent AF and permanent AF). Ectopic focus is the abnormal pacemaker site out of the sinoatrial node [27]. It has been well accepted that the most common causes of focal ectopic activity are afterdepolarizations, in more detail, the delayed afterdepolarizations are usually attributed to the transient diastolic rise in cytoplasmic Ca2+ concentration. Therefore, calcium plays a multidimensional role in the pathophysiology of AF [28]. Results from both in-vivo and in-vitro studies have shown increased susceptibility to AF in a rabbit model of chronic MI. Progressive T-tubule disorganisation and reduced synchrony of Ca2+ release were observed in murine cardiomyocytes from a mice model of post-MI heart failure [29]. In fact, reduced Ca2+ release despite preserved Ca2+ in sarcoplasmic reticulum content is the major factor in the contractile dysfunction of persistent AF [30].
Laparoscopic management of a broad ligament ectopic pregnancy with a literature review
Published in Journal of Obstetrics and Gynaecology, 2022
Cihan Kaya, Özgür Aslan, Berk Gürsoy
The management of broad ligament EP could be performed either laparotomy or laparoscopy, considering the experience of the surgeon, the facilities of the operation room, and the vital signs of the patient (Deneke 1997; Deshpande 1999; Phupong 2003; Siow 2004; Apantaku 2006; Cormio 2006; Nayar and Nair 2016; Bettaiah and Kamath 2017; Cho 2018; Sassi 2018; Azhar 2020). Apart from the type of surgery, massive bleeding can be observed due to severe invasion of the surrounding fragile and branching vessels (Sassi et al. 2018). A laparotomy could opt as the first surgical approach due to an increased bleeding risk, size of the mass, and invasion of the other pelvic structures (Phupong et al. 2003). In a study by Azhar et al. (2020), the surgery was converted from laparoscopy to laparotomy due to active bleeding. Meticulous hemostasis and complete removal of the EP, as performed in our case, is the crucial part of the surgery. To decrease the bleeding, diluted vasopressin may be injected around the ectopic focus (Bettaiah and Kamath 2017). The salpingectomy may reduce the risk of future EP in addition to the total excision of ectopic focus. On the other hand, the intact fallopian tube could be preserved in patients who wish to maintain fertility (Nayar and Nair 2016). The concern regarding a partial salpingectomy is an increased frequency of EP that may occur in the stump (Azhar et al. 2020).
Successful laparoscopic treatment of asymptomatic heterotopic pregnancy after spontaneous conception
Published in Journal of Obstetrics and Gynaecology, 2019
Nefise Nazlı Yenigul, Osman Asicioglu, Işıl Ayhan
Although consideration of a spontaneous HP is the most important diagnostic criterion, it is very difficult to confirm. There are no specific laboratory findings for HP; the measuring the level of beta human chorionic gonadotropin is useless (Alptekin and Dal 2014). TVUS has a more important place in the diagnosis of HP, but it is not completely reliable. According to a review by Talbot et al. (2011), only 66% of cases were diagnosed by ultrasound. The ectopic focus can be mistaken for the corpus luteum or pre-existing cysts. In addition, a single sonographic evaluation may be insufficient for diagnosis, as in our case, and repeated sonography increases the potential of identifying a HP (Simsek et al. 2008).