Volume conductor effects involved in the genesis of the P wave

EP Europace ◽  
2005 ◽  
Vol 7 (s2) ◽  
pp. S30-S38 ◽  
Author(s):  
Peter M. van Dam ◽  
Adriaan van Oosterom
Keyword(s):  
Body Surface ◽  
Electric Activity ◽  
The Body ◽  
Volume Conductor ◽  
P Wave ◽  
Major Influence ◽  
Resonance Imaging ◽  
Surface Potentials ◽  
Volume Conductor Model ◽  
Wave Morphology

Abstract Aim To assess the effect of inhomogeneities in the conductivity of different tissues, such as blood and lung tissue, on the body surface potentials generated by atrial electrical activity. Methods A 64-lead ECG from a healthy subject was recorded. The subject's geometries of torso, lungs, heart, and blood cavities were derived by magnetic resonance imaging. These geometries were used to construct a numerical volume conductor model. The boundary element method was applied to simulate the potentials on the surface of the thorax generated by the atria. The equivalent double layer served as the source description during depolarization. Recorded body surface potentials were used as a check on the simulations. Subsequently, the conductivities in the model were varied to determine their influence on P wave morphology and amplitude. Results The model with realistic conductivity values for blood and lungs produced potentials that closely matched the measured ones (correlation 98%). The subsequent variation of conductivity of blood and lungs revealed a major influence on P wave morphology and amplitude: a mean reduction in amplitude by 42%, with pronounced inter-lead differences. Conclusion The inhomogeneities of lungs and atrial blood cavities need to be incorporated in volume conductor models linking atrial electric activity to body surface potentials.

The Role of Computer Modeling in Electrocardiography

1990 ◽  
Vol 29 (04) ◽  
pp. 282-288 ◽  
Author(s):  
A. van Oosterom
Keyword(s):  
Electrical Activity ◽  
Computer Modeling ◽  
Body Surface ◽  
Electrical Current ◽  
The Body ◽  
Volume Conductor ◽  
Current Generator ◽  
Cardiac Electrical Activity ◽  
Source Models

AbstractThis paper introduces some levels at which the computer has been incorporated in the research into the basis of electrocardiography. The emphasis lies on the modeling of the heart as an electrical current generator and of the properties of the body as a volume conductor, both playing a major role in the shaping of the electrocardiographic waveforms recorded at the body surface. It is claimed that the Forward-Problem of electrocardiography is no longer a problem. Several source models of cardiac electrical activity are considered, one of which can be directly interpreted in terms of the underlying electrophysiology (the depolarization sequence of the ventricles). The importance of using tailored rather than textbook geometry in inverse procedures is stressed.

scholarly journals Contributions of the 12 Segments of Left Ventricular Myocardium to the Body Surface Potentials

2007 ◽  
pp. 300-309
Author(s):  
Juho Väisänen ◽  
Jesús Requena-Carrión ◽  
Felipe Alonso-Atienza ◽  
Jari Hyttinen ◽  
José Luis Rojo-Álvarez ◽  
...  
Keyword(s):  
Body Surface ◽  
Ventricular Myocardium ◽  
Left Ventricular ◽  
The Body ◽  
Left Ventricular Myocardium ◽  
Surface Potentials

Analysis of six cancer patients with persistent left superior vena cava identified during central venous access device placement via an intracavitary electrocardiogram

2021 ◽  
pp. 112972982110455
Author(s):  
Xinpeng Wang ◽  
Yong Yang ◽  
Jing Dong ◽  
Xiaozheng Wang ◽  
Yuanyuan Zheng ◽  
...  
Keyword(s):  
Body Surface ◽  
Superior Vena ◽  
Central Venous Access ◽  
Vena Cava ◽  
Venous Access ◽  
The Body ◽  
P Wave ◽  
P Waves ◽  
Venous Access Device ◽  
Surface Electrocardiogram

Persistent left superior vena cava (PLSVC) is a rare congenital anomaly. PLSVC can be associated with clinically significant atrial septal defect (ASD) or ventricular septal defect (VSD). It is usually asymptomatic and accidentally detected during invasive procedures or imaging examinations. However, whether central venous access device (CVAD) can be placed and used in patients with PLSVC is controversial. A total of six patients were diagnosed with PLSVC and confirmed by chest CT among 3391 cancer patients who underwent CVAD placement via intracavitary electrocardiogram (IC-EKG) at the Venous Access Center (VAC) from May 2019 to December 2020. The CVADs (peripherally inserted central catheter in four patients and Ports in two patients) of these six patients were left in PLSVC. We analyzed changes in the P-wave in the IC-EKG during CVAD placement and the characteristics of the body surface electrocardiogram in these patients and discussed the catheter tip position in PLSVC. All six patients showed negative P-waves in lead II via IC-EKG from the beginning of catheterization: four patients showed negative P-waves and two showed biphasic P-waves in the body surface electrocardiogram (lead III) before catheterization. CVAD function was normal and no obvious complications were observed during the treatment of these patients. The total retention time of CVADs was 1537 days. For patients with a negative P-wave in lead II via IC-EKG during catheterization, especially in those with a negative or biphasic P-wave in lead III of the body surface electrocardiogram, PLSVC should be considered. CVAD insertion in patients with type I PLSVC is safe under certain conditions, with the proper tip position in the middle to lower part of PLSVC.

The QRS electrocardiogram, epicardiogram, vectorcardiogram and ventricular excitation of swine

1960 ◽  
Vol 198 (3) ◽  
pp. 537-542 ◽  
Author(s):  
Robert L. Hamlin
Keyword(s):  
Right Ventricular ◽  
Body Surface ◽  
The Body ◽  
Ventricular Free Wall ◽  
Activation Process ◽  
Free Wall ◽  
Right Ventricular Free Wall ◽  
Surface Potentials ◽  
Ventricular Activation ◽  
Three Components

The ventricular activation process of normal pigs as estimated qualitatively from body surface potentials and epicardial electrograms is similar to that accurately described for the dog. Ventricular excitation may be divided sequentially into three components: interventricular septal from left to right, ventricular free-wall from endocardium to epicardium, and septal and ventricular basilar in an apico-basilar direction. The differences between the body surface potentials recorded from the dog and from the pig lies in the greater dorsal magnitude of the terminal basilar forces in the pig.

scholarly journals A Fully-Coupled Electro-Mechanical Whole-Heart Computational Model: Influence of Cardiac Contraction on the ECG

2021 ◽  
Vol 12 ◽  
Author(s):  
Robin Moss ◽  
Eike Moritz Wülfers ◽  
Steffen Schuler ◽  
Axel Loewe ◽  
Gunnar Seemann
Keyword(s):  
Body Surface ◽  
In Silico ◽  
Computational Cost ◽  
Cardiac Motion ◽  
The Body ◽  
Cardiac Contraction ◽  
P Wave ◽  
Qrs Complex ◽  
T Wave ◽  
Whole Heart

The ECG is one of the most commonly used non-invasive tools to gain insights into the electrical functioning of the heart. It has been crucial as a foundation in the creation and validation of in silico models describing the underlying electrophysiological processes. However, so far, the contraction of the heart and its influences on the ECG have mainly been overlooked in in silico models. As the heart contracts and moves, so do the electrical sources within the heart responsible for the signal on the body surface, thus potentially altering the ECG. To illuminate these aspects, we developed a human 4-chamber electro-mechanically coupled whole heart in silico model and embedded it within a torso model. Our model faithfully reproduces measured 12-lead ECG traces, circulatory characteristics, as well as physiological ventricular rotation and atrioventricular valve plane displacement. We compare our dynamic model to three non-deforming ones in terms of standard clinically used ECG leads (Einthoven and Wilson) and body surface potential maps (BSPM). The non-deforming models consider the heart at its ventricular end-diastatic, end-diastolic and end-systolic states. The standard leads show negligible differences during P-Wave and QRS-Complex, yet during T-Wave the leads closest to the heart show prominent differences in amplitude. When looking at the BSPM, there are no notable differences during the P-Wave, but effects of cardiac motion can be observed already during the QRS-Complex, increasing further during the T-Wave. We conclude that for the modeling of activation (P-Wave/QRS-Complex), the associated effort of simulating a complete electro-mechanical approach is not worth the computational cost. But when looking at ventricular repolarization (T-Wave) in standard leads as well as BSPM, there are areas where the signal can be influenced by cardiac motion of the heart to an extent that should not be ignored.

Electrodynamic Heart Model Construction and ECG Simulation

2006 ◽  
Vol 45 (05) ◽  
pp. 564-573 ◽  
Author(s):  
M. Huo ◽  
Q. Wei ◽  
F. Liu ◽  
S. Crozier ◽  
L. Xia
Keyword(s):  
Myocardial Ischemia ◽  
Body Surface ◽  
The Body ◽  
Heart Model ◽  
Surface Potentials ◽  
T Wave ◽  
Torso Model ◽  
St Segment ◽  
Surface Ecg ◽  
Cardiac Excitation

Summary Objectives: In this paper, we present a unified electrodynamic heart model that permits simulations of the body surface potentials generated by the heart in motion. The inclusion of motion in the heart model significantly improves the accuracy of the simulated body surface potentials and therefore also the 12-lead ECG. Methods: The key step is to construct an electromechanical heart model. The cardiac excitation propagation is simulated by an electrical heart model, and the resulting cardiac active forces are used to calculate the ventricular wall motion based on a mechanical model. The source-field point relative position changes during heart systole and diastole. These can be obtained, and then used to calculate body surface ECG based on the electrical heart-torso model. Results: An electromechanical biventricular heart model is constructed and a standard 12-lead ECG is simulated. Compared with a simulated ECG based on the static electrical heart model, the simulated ECG based on the dynamic heart model is more accordant with a clinically recorded ECG, especially for the ST segment and T wave of a V1-V6 lead ECG. For slight-degree myocardial ischemia ECG simulation, the ST segment and T wave changes can be observed from the simulated ECG based on a dynamic heart model, while the ST segment and T wave of simulated ECG based on a static heart model is almost unchanged when compared with a normal ECG. Conclusions: This study confirms the importance of the mechanical factor in the ECG simulation. The dynamic heart model could provide more accurate ECG simulation, especially for myocardial ischemia or infarction simulation, since the main ECG changes occur at the ST segment and T wave, which correspond with cardiac systole and diastole phases.

Dimensions of Central Venous Structures in Humans Measured in vivo using Magnetic Resonance Imaging: Implications for Central-Vein Catheter Dimensions

2002 ◽  
Vol 25 (2) ◽  
pp. 107-123 ◽  
Author(s):  
Z.J. Twardowski ◽  
R.M. Seger
Keyword(s):  
Surface Area ◽  
Body Surface Area ◽  
Body Surface ◽  
The Body ◽  
Upper Body ◽  
Central Vein ◽  
Resonance Imaging ◽  
Vein Catheter ◽  
Central Vein Catheter

The tip of a central vein catheter for hemodialysis should be located in the upper right atrium for the best performance. Hemodialysis catheters do have internal diameters unadjusted to the catheter length; however, the longer the catheter the slower the flow at the same pressure difference. On the other hand, the catheter diameter cannot be so large as to fill the vein too tightly as it predisposes to damage of the vein wall, thrombosis and stenosis. Therefore, the catheter length and diameter should be appropriate for the patient. For this purpose, the exact dimensions of the venous system in vivo should be known. In this study we correlated the anthropometric measurements and the dimensions of the large upper body veins in 31 adult volunteers. After deep inspiration, magnetic resonance imaging of the chest was performed in three planes; the positions of specific points in the three-dimensional coordinate system were measured, and the distance to adjacent points was calculated according to the analytic geometry formula. The total length from the catheter entry point to the right atrium was the sum of distances between the adjacent points. The lengths of the veins were correlated with the body anthropometric measurements (height, weight, body surface area, bi-acromion span, and height plus bi-acromion span). The best overall correlations of the lengths and diameters of the large upper body veins are with the body surface area. A table is included to guide the selection of the total catheter length and diameter in relation to the body surface area and insertion site.

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