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Designing a Low-Cost ECG Sensor and Monitor: Practical Considerations and Measures
Published in Daniel Tze Huei Lai, Rezaul Begg, Marimuthu Palaniswami, Healthcare Sensor Networks, 2016
Ahsan H. Khandoker, Brian A. Walker
The P wave is caused by atrial depolarization (contraction). The QRS complex represents ventricular depolarization, and the T wave ventricular repolarization (Gardiner 1981). Heart disease can be diagnosed on close inspection of these deflection components. For example, close RR intervals would indicate a high risk of ventricular fibrillation. Stray P waves which do not appear to be part of the cardiac cycle indicate complete heart block, which causes fainting and palpitations. Missing P waves are a strong indication of atrial fibrillation, which increases the risk of stroke. A patient who has atrial fibrillation accompanied by complete heart block would probably require a pacemaker (http://www.ecglibrary.com/). Flat or depressed ST segments could indicate coronary artery disease, which is the leading cause of death worldwide (Carson-DeWitt 2007). Sleep apnoea can be detected using the ECG (Khandoker et al. 2009) by analysing the variation in RR intervals—in particular, the RR interval variations can be analysed in the frequency domain using the Hilbert transform (Mietus et al. 2000). Interpreting abnormalities in an ECG signal is not an easy task, as it is very difficult to determine how long the abnormalities have been present. Some people are even born with such abnormalities (Cohen 2005).
Acquired Brain Injury Rehabilitation: What Can HRV Tell You?
Published in Herbert F. Jelinek, David J. Cornforth, Ahsan H. Khandoker, ECG Time Series Variability Analysis, 2017
Ian J. Baguley, Melissa T. Nott
The heart has two intrinsic drivers of HR, the atrioventricular (AV) and sinoatrial (SA) nodes, connected by a myelinated nerve tract known as the bundle of His. In the normal heart, the AV node has an intrinsic rate of around 40 beats per minute (bpm), and in conditions such as complete heart block, the ventricles adopt this slow rate of contraction. Where the SA node and bundle of His are intact, the higher intrinsic rate of the SA node (60–80 bpm at rest) drives the rate of ventricular contraction.
Ablation
Published in John G Webster, Minimally Invasive Medical Technology, 2016
Chemical substances can also be used to ablate unwanted tissues. As early as 1964 a complete heart block was induced in dogs by the injection of formaldehyde in the region of the bundle of His. Damiano et al (1986) could lower the fibrillation threshold of ventricular myocardium in dogs by administering intraoperatively Lugol’s solution into the ventricular endocardium. A suitable chemical for ablation must be safe and effective and require a brief contact time.
Can we reduce conduction disturbances following transcatheter aortic valve replacement?
Published in Expert Review of Medical Devices, 2020
Alberto Alperi Garcia, Guillem Muntané-Carol, Lucia Junquera, David del Val, Laurent Faroux, François Philippon, Josep Rodés-Cabau
In summary, no temporary pacing or prolonged surveillance was recommended in those patients with no ECG changes following the TAVR procedure (irrespective of preexisting conduction abnormalities, except for RBBB). Temporary pacing and a more prolonged (>24 h) in-hospital ECG surveillance was recommended in those patients with preexisting RBBB or those with ECG changes post-TAVR (including new-onset LBBB). The recommendation for permanent PPI was mainly driven by the occurrence of advanced conduction disturbances or complete heart block, but it was stated that PPI could also be considered in some high-risk situation despite the absence of advanced conduction disturbances. This consensus document may contribute to a more uniform management of conduction disturbances post-TAVR, and the management algorithm proposed in the document is currently being prospectively evaluated in a large cohort of patients (PROMOTE study).
Heart failure and right ventricular pacing – how to avoid the need for cardiac resynchronization therapy
Published in Expert Review of Medical Devices, 2019
Maria F. Paton, Klaus K. Witte
The principle issue facing implanters and their patients is that despite the adverse effects of RV pacing, many patients will not develop LVSD or HF as a consequence of long-term RV pacing, while others will develop it rapidly and follow a fulminant course [5]. The benefit of more complex approaches is likely to be limited to a subgroup of patients that must be identified prior to the initial procedure. Despite considerable investment, the features predicting preventable future clinical deterioration due to incident pacing-related LV dysfunction remain elusive although the presence of pre-existing cardiovascular co-morbidities increases the risk .Even the simplest clinical feature, complete heart block recorded indication is unreliable since at long-term follow-up a large proportion will not require high amounts of RV pacing (Figure 3) [76].
Comparison of methods for delivering cardiac resynchronization therapy: electrical treatment targets and mechanisms of action
Published in Expert Review of Medical Devices, 2023
Florentina Simader, Ahran Arnold, Zachary Whinnett
LBBAP-CRT can result in restoration of normal LV activation times and patterns. However, unlike HBP, right ventricular activation does not typically occur via the conduction system, which results in a delay in RV activation. This can be overcome by programming AV delays promoting fusion between intrinsic activation of the right ventricle and activation of the left bundle from LBBAP to deliver a narrower QRS. However, this is not possible in patients with very long PR intervals or complete heart block and may also result in suboptimal left-sided AV delays. Therefore, LBBAP-CRT is a very promising technique for delivering CRT; however, there is a need for RCTs to investigate this technique’s impact on clinical outcomes.