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Cardiovascular Disease
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
Approximately 1–2% of the population have dual AV node physiology with a second pathway between the atria and ventricle within the AV node. A re-entry tachycardia (atrioventricular nodal re-entrant tachycardia [AVNRT]) (Figure 7.29a) occurs within the AV node due to fast and slow conduction. This precipitates a tachycardia by simultaneously activating both the atrium and ventricle.
Congestive Heart Failure
Published in Jahangir Moini, Matthew Adams, Anthony LoGalbo, Complications of Diabetes Mellitus, 2022
Jahangir Moini, Matthew Adams, Anthony LoGalbo
In hypertrophic cardiomyopathy, the myocardium is abnormal in its cells and myofibrils. Restrictive cardiomyopathy involves endocardial thickening or myocardial infiltration in one or both ventricle – usually the left ventricle is affected with one-sided disease. There may be myocyte death, infiltration of the papillary muscle, compensatory myocardial hypertrophy, and fibrosis. The mitral or tricuspid valves may become dysfunctional, causing regurgitation. In the AV valve, functional regurgitation may be caused by myocardial infiltration or thickening of the endocardium. When the nodal and conduction tissues are damaged, the SA and AV nodes malfunction. This can cause various amounts of block of both nodes. The primary hemodynamic outcome is diastolic dysfunction. The affected ventricle becomes rigid and noncompliant. There is impaired diastolic filling and a high filling pressure. Pulmonary venous hypertension develops. Systolic function may be greatly impaired if the compensatory hypertrophy of fibrosed or infiltrated ventricles is insufficient. If mural thrombi form, systemic emboli can develop.
Ablation of SVT (AVNRT and AVRT)
Published in Andrea Natale, Oussama M. Wazni, Kalyanam Shivkumar, Francis E. Marchlinski, Handbook of Cardiac Electrophysiology, 2020
Kushwin Rajamani, Patrick Tchou
There are two approaches to slow AV nodal pathway ablation. One is called an anatomic approach while the other uses electrogram characteristics to guide ablation. In reality, both approaches use electrogram guidance as well as anatomic landmarks.
Complete atrioventricular block with diastolic mitral regurgitation due to severe lithium intoxication. A case report
Published in Acta Cardiologica, 2022
Theodoros Kalpakos, Gaëlle Vermeersch, Bart Hendriks, Paul Vermeersch
As far as the aetiology of complete AV block is concerned, there was no other obvious cause of AV dissociation except for lithium intoxication. We performed extensive toxicology tests which showed severely elevated lithium blood levels (5.9 mmol/L, limit 1.5 mmol/L), whereas the rest of the toxicology screening was negative. The patient was not taking any beta blockers or other medicine with negative chronotropic or dromotropic effects. There were no arguments for acute myocardial ischaemia: anamnesis and hetero-anamnesis were both negative, the patient had a low cardiovascular risk profile, the ECG’s showed no signs of ischaemia and the cardiac ultrasound revealed a normal regional LV wall motion with a hyperkinetic LV due to hypovolemia. Mild troponinemia was present, however, without kinetics. We attributed mild troponinemia to hypovolemic shock, acute kidney failure and AV conduction abnormalities [5].
Heterotaxy Syndrome with Increased Nuchal Translucency and Normal Karyotype Associated with Complex Systemic Venous Return. Ultrasound Diagnosis with Autopsy Correlation
Published in Fetal and Pediatric Pathology, 2022
Gabriele Tonni, Maria Paola Bonasoni, Gianpaolo Grisolia, Maria Bellotti, Edward Araujo Júnior
A further targeted examination at a tertiary care center showed increased nuchal fold (> 6 mm), dextrocardia with normal pulmonary venous return to the left atrium. ASVR consisted in IVC interruption with azygos continuation draining into the left persistent superior vena cava (LPSVC). The right superior vena cava (RSVC) was absent while the PLSVC drained directly into the left atrium with no coronary sinus (unroofed). There was atrial septation with the left atrium of large dimension. There was linear insertion of both atrioventricular (AV) valves but with no sign of AV canal. A large VSD with right-sided aorta in malalignment over-rode the VSD. The aorta was shifted to the right with the aortic arch lying on the right of the ductal arch but on the left of the trachea. The liver and the gallbladder were in the median position.
Antenatal management and neonatal outcomes of monochorionic twin pregnancies in a tertiary teaching hospital: a 10-year review
Published in Journal of Obstetrics and Gynaecology, 2021
Dominique A. Badr, Elisa Bevilacqua, Andrew Carlin, Kalina Gajewska, Elisa Done, Teresa Cos Sanchez, Camille Olivier, Jacques C. Jani
Twin pregnancy is associated with an increased rate of maternal and foetal complications. Monochorionic (MC) twins, which account for approximately 20–30% of all twin pregnancies (Cameron et al. 1983), represent an even higher risk due to a shared placentation and the presence of inter-twin vascular anastomoses and therefore pose a significant management challenge. Vascular anastomoses facilitate the flow of blood from one foetus to another of which there are three recognised types: artery-to-artery, vein-to-vein and artery-to-vein. Arterio-venous (AV) anastomoses are uni-directional anastomoses where blood flows from an artery of one twin to a vein of the co-twin via a shared cotyledon (also called ‘deep-anastomoses’). Arterio-arterial (AA) and veno-venous (VV) anastomoses are ‘superficial’ anastomoses since they lie on the placental foetal surface and these are bi-directional (Lewi et al. 2013; Slaghekke et al. 2016). It is these vascular anastomoses, in particular, the AV subtypes, which are responsible for the development of the twin-twin transfusion syndrome (TTTS) and twin anaemia-polycythaemia sequence (TAPS) in complicated MC pregnancies (Kilby and Bricker L on behalf of the Royal College of Obstetricians and Gynaecologists 2016).