Vectorcardiography

Last updated
Vectorcardiography
Vektorkardiogramm kgm-normal.jpg
Normal vectorcardiogram
ICD-9-CM 89.53
MeSH D014672

Vectorcardiography (VCG) is a method of recording the magnitude and direction of the electrical forces that are generated by the heart by means of a continuous series of vectors that form curving lines around a central point. [1]

Contents

Vectorcardiography was developed by E. Frank in the mid 1950s. [2] [3] Since the human body is a three-dimensional structure, the basic idea is to construct three orthogonal leads containing all the electric information. The three leads are represented by right-left axis (X), head-to-feet axis (Y) and front-back (anteroposterior) axis (Z).

To calculate Frank's leads X, Y and Z using the standard leads system, the following expressions [4] are used:

X = -(-0.172 V1 - 0.074 V2 + 0.122 V3 + 0.231 V4 + 0.239 V5 + 0.194 V6 + 0.156 DI - 0.010 DII) (1)

Y = (0.057 V1 - 0.019 V2 - 0.106 V3 - 0.022 V4 + 0.041 V5 + 0.048 V6 - 0.227 DI + 0.887 DII) (2)

Z = -(-0.229 V1 - 0.310 V2 - 0.246 V3 - 0.063 V4 + 0.055 V5 + 0.108 V6 + 0.022 DI + 0.102 DII) (3)

There are different criteria how at to evaluate a vectorcardiogram created by various researchers. Grygoriy Risman presents these different methods, which were developed over half a century and offers an advanced approach called spatial vectorcardiometry (SVCM). [5] The original Russian thesis is filed in the Odesa National Medical University. [6] Recently, Bipolar Precordial Leads exploring the right to left axis combined with averaged unipolar precordial leads allowed to produce sectorial VCG loops in the horizontal plane. [7]

Spatial QRS-T angle

The spatial QRS-T angle (SA) is derived from a vectorcardiogram, which is a three-dimensional representation of the 12-lead electrocardiogram (ECG) created with a computerized matrix operation. The SA is the angle of deviation between two vectors; the spatial QRS-axis representing all of the electrical forces produced by ventricular depolarization and the spatial T-axis representing all the electrical forces produced by ventricular repolarization. [8] The SA is indicative of the difference in orientation between the ventricular depolarization and repolarization sequence.[ citation needed ]

In healthy individuals, the direction of ventricular depolarization and repolarization is relatively reversed; this creates a sharp SA. [9] There is high individual variability and gender difference in the magnitude of the SA. The mean, normal SA in healthy young adult females and males is 66° and 80°, respectively, [9] and very similar magnitudes are found in the elderly population (65 years and older). [10] In ECG analysis, the SA is categorized into normal (below 105°), borderline abnormal (105–135°) and abnormal (greater than 135°). [11] A broad SA results when the heart undergoes pathological changes and is reflected in a discordant ECG. A large SA indicates an altered ventricular repolarization sequence, and may be the result of structural and functional myocardial changes that induce regional shortening in action potential duration and impaired ion channel functioning. [12]

Current standard ECG markers of repolarization abnormalities include ST depression, T wave inversion and QT prolongation. Many studies have investigated the prognostic strength of the SA for cardiac morbidity and mortality compared to these and other ECG parameters. In treated hypertensive patients, the SA was significantly larger in patients with elevated blood pressure compared to those with lower blood pressure values and a discrimination between patients with high and low blood pressure could not be detected using other ECG parameters. [13] In the Rotterdam Study with men and women aged 55 years and older, having an abnormal SA significantly increased the hazard ratios for cardiac death, sudden cardiac death, non-fatal cardiac events (infarction, coronary interventions) and total mortality. Independently, the SA was a stronger risk indicator of cardiac mortality compared to the other cardiovascular and ECG risk factors analyzed. [11] The Women's Health Initiative study concluded that a wide SA was the strongest predictor for incident coronary heart failure risk and a dominant risk factor for all cause mortality compared to several other ECG parameters. [12] The SA also increases accuracy of diagnosing left ventricular hypertrophy (LVH). Using only conventional ECG criteria to diagnose LVH the diagnostic accuracy was 57%, however the inclusion of the SA significantly improved the diagnostic accuracy to 79%. [14]

The SA is not routinely measured in clinical ECG examination even though the computerized vectorcardiography software is widely available, efficient and is not affected by observational biases unlike other ECG parameters. [13] The SA is a sensitive marker of repolarization aberrations and with further research support the SA will likely become clinically applied in predicting cardiac morbidity and mortality.[ citation needed ]

A simplified criteria in using the vectorcardiogram has the ability to identify patients with a diaphragmatic infarction not apparent in the electrocardiogram. [15]

See also

Related Research Articles

<span class="mw-page-title-main">Electrocardiography</span> Examination of the hearts electrical activity

Electrocardiography is the process of producing an electrocardiogram, a recording of the heart's electrical activity through repeated cardiac cycles. It is an electrogram of the heart which is a graph of voltage versus time of the electrical activity of the heart using electrodes placed on the skin. These electrodes detect the small electrical changes that are a consequence of cardiac muscle depolarization followed by repolarization during each cardiac cycle (heartbeat). Changes in the normal ECG pattern occur in numerous cardiac abnormalities, including:

<span class="mw-page-title-main">Premature ventricular contraction</span> Skipped beat with ventricular origin

A premature ventricular contraction (PVC) is a common event where the heartbeat is initiated by Purkinje fibers in the ventricles rather than by the sinoatrial node. PVCs may cause no symptoms or may be perceived as a "skipped beat" or felt as palpitations in the chest. PVCs do not usually pose any danger.

<span class="mw-page-title-main">Cardiac conduction system</span> Aspect of heart function

The cardiac conduction system transmits the signals generated by the sinoatrial node – the heart's pacemaker, to cause the heart muscle to contract, and pump blood through the body's circulatory system. The pacemaking signal travels through the right atrium to the atrioventricular node, along the bundle of His, and through the bundle branches to Purkinje fibers in the walls of the ventricles. The Purkinje fibers transmit the signals more rapidly to stimulate contraction of the ventricles.

<span class="mw-page-title-main">Torsades de pointes</span> Type of abnormal heart rhythm

Torsades de pointes, torsade de pointes or torsades des pointes is a specific type of abnormal heart rhythm that can lead to sudden cardiac death. It is a polymorphic ventricular tachycardia that exhibits distinct characteristics on the electrocardiogram (ECG). It was described by French physician François Dessertenne in 1966. Prolongation of the QT interval can increase a person's risk of developing this abnormal heart rhythm, occurring in between 1% and 10% of patients who receive QT-prolonging antiarrhythmic drugs.

<span class="mw-page-title-main">Ventricular tachycardia</span> Abnormally fast rhythm of the hearts ventricles

Ventricular tachycardia is a cardiovascular disorder in which fast heart rate occurs in the ventricles of the heart. Although a few seconds of VT may not result in permanent problems, longer periods are dangerous; and multiple episodes over a short period of time are referred to as an electrical storm. Short periods may occur without symptoms, or present with lightheadedness, palpitations, shortness of breath, chest pain, and decreased level of consciousness. Ventricular tachycardia may lead to coma and persistent vegetative state due to lack of blood and oxygen to the brain. Ventricular tachycardia may result in ventricular fibrillation (VF) and turn into cardiac arrest. This conversion of the VT into VF is called the degeneration of the VT. It is found initially in about 7% of people in cardiac arrest.

<span class="mw-page-title-main">QT interval</span> Measurement made on an electrocardiogram

The QT interval is a measurement made on an electrocardiogram used to assess some of the electrical properties of the heart. It is calculated as the time from the start of the Q wave to the end of the T wave, and approximates to the time taken from when the cardiac ventricles start to contract to when they finish relaxing. An abnormally long or abnormally short QT interval is associated with an increased risk of developing abnormal heart rhythms and sudden cardiac death. Abnormalities in the QT interval can be caused by genetic conditions such as long QT syndrome, by certain medications such as sotalol or pitolisant, by disturbances in the concentrations of certain salts within the blood such as hypokalaemia, or by hormonal imbalances such as hypothyroidism.

<span class="mw-page-title-main">Left ventricular hypertrophy</span> Medical condition

Left ventricular hypertrophy (LVH) is thickening of the heart muscle of the left ventricle of the heart, that is, left-sided ventricular hypertrophy and resulting increased left ventricular mass.

<span class="mw-page-title-main">T wave</span> Electrocardiogram waveform representing repolarization of the hearts ventricles

In electrocardiography, the T wave represents the repolarization of the ventricles. The interval from the beginning of the QRS complex to the apex of the T wave is referred to as the absolute refractory period. The last half of the T wave is referred to as the relative refractory period or vulnerable period. The T wave contains more information than the QT interval. The T wave can be described by its symmetry, skewness, slope of ascending and descending limbs, amplitude and subintervals like the Tpeak–Tend interval.

<span class="mw-page-title-main">QRS complex</span> Electrocardiogram waveform representing ventricular contraction in the heart

The QRS complex is the combination of three of the graphical deflections seen on a typical electrocardiogram. It is usually the central and most visually obvious part of the tracing. It corresponds to the depolarization of the right and left ventricles of the heart and contraction of the large ventricular muscles.

<span class="mw-page-title-main">Atrioventricular block</span> Medical condition

Atrioventricular block is a type of heart block that occurs when the electrical signal traveling from the atria, or the upper chambers of the heart, to ventricles, or the lower chambers of the heart, is impaired. Normally, the sinoatrial node produces an electrical signal to control the heart rate. The signal travels from the SA node to the ventricles through the atrioventricular node. In an AV block, this electrical signal is either delayed or completely blocked. When the signal is completely blocked, the ventricles produce their own electrical signal to control the heart rate. The heart rate produced by the ventricles is much slower than that produced by the SA node.

<span class="mw-page-title-main">Left bundle branch block</span> Medical condition

Left bundle branch block (LBBB) is a conduction abnormality in the heart that can be seen on an electrocardiogram (ECG). In this condition, activation of the left ventricle of the heart is delayed, which causes the left ventricle to contract later than the right ventricle.

<span class="mw-page-title-main">Right axis deviation</span> Medical condition

The electrical axis of the heart is the net direction in which the wave of depolarization travels. It is measured using an electrocardiogram (ECG). Normally, this begins at the sinoatrial node ; from here the wave of depolarisation travels down to the apex of the heart. The hexaxial reference system can be used to visualise the directions in which the depolarisation wave may travel.

<span class="mw-page-title-main">ST elevation</span> Elevation of the ST segment on an electrocardiogram

ST elevation is a finding on an electrocardiogram wherein the trace in the ST segment is abnormally high above the baseline.

<span class="mw-page-title-main">ST depression</span> Depression of the ST segment on an electrocardiogram

ST depression refers to a finding on an electrocardiogram, wherein the trace in the ST segment is abnormally low below the baseline.

<span class="mw-page-title-main">P wave (electrocardiography)</span> Electrocardiogram waveform representing atrial contraction

In cardiology, the P wave on an electrocardiogram (ECG) represents atrial depolarization, which results in atrial contraction, or atrial systole.

<span class="mw-page-title-main">Left axis deviation</span> Heart condition

In electrocardiography, left axis deviation (LAD) is a condition wherein the mean electrical axis of ventricular contraction of the heart lies in a frontal plane direction between −30° and −90°. This is reflected by a QRS complex positive in lead I and negative in leads aVF and II.

<span class="mw-page-title-main">Electrocardiography in myocardial infarction</span>

Electrocardiography in suspected myocardial infarction has the main purpose of detecting ischemia or acute coronary injury in emergency department populations coming for symptoms of myocardial infarction (MI). Also, it can distinguish clinically different types of myocardial infarction.

A diagnosis of myocardial infarction is created by integrating the history of the presenting illness and physical examination with electrocardiogram findings and cardiac markers. A coronary angiogram allows visualization of narrowings or obstructions on the heart vessels, and therapeutic measures can follow immediately. At autopsy, a pathologist can diagnose a myocardial infarction based on anatomopathological findings.

<span class="mw-page-title-main">Benign early repolarization</span> Medical condition

Benign early repolarization (BER) or early repolarization is found on an electrocardiogram (ECG) in about 1% of those with chest pain. It is diagnosed based on an elevated J-point / ST elevation with an end-QRS notch or end-QRS slur and where the ST segment concave up. It is believed to be a normal variant.

Sgarbossa's criteria are a set of electrocardiographic findings generally used to identify myocardial infarction in the presence of a left bundle branch block (LBBB) or a ventricular paced rhythm.

References

  1. ↑ "Medical Definition of Vectorcardiography". www.merriam-webster.com. Retrieved June 8, 2017.
  2. ↑ Burch, G.E. (1985). "The history of vectorcardiography". Medical History Supplement. 5 (5): 103–131. doi:10.1017/S002572730007054X. PMC   2557408 . PMID   3915520.
  3. ↑ Frank, E (1956). "An Accurate, Clinically Practical System For Spatial Vectorcardiography". Circulation. 13 (5): 737–749. doi: 10.1161/01.CIR.13.5.737 . PMID   13356432.
  4. ↑ G Daniel; G Lissa; D Medina Redondo; et al. (2007). "Real-time 3D vectorcardiography: An application for didactic use". Journal of Physics: Conference Series. 90 (1): 012013. Bibcode:2007JPhCS..90a2013D. doi: 10.1088/1742-6596/90/1/012013 .
  5. ↑ "Vektorkardiometrie - Eine Methode der Vektorkardiographie". www.vectorcardiometry.tk (in German). Retrieved June 8, 2017.
  6. ↑ "Распределение пространственных моментных викторов пробега волны возбуждения процесса дополяризации миокарда желудочков у здоровых спортсменов, больных с легочным сердцем и почечной гипертонией Каталог Бібліотека ОНМедУ". info.odmu.edu.ua (in Russian). Archived from the original on 22 October 2013. Retrieved June 8, 2017.
  7. ↑ Mc Loughlin, MJ (2020). "Precordial bipolar leads: A new method to study anterior acute myocardial infarction". J Electrocardiol. 59 (2): 45–64. doi:10.1016/j.jelectrocard.2019.12.017. PMID   31986362. S2CID   210935474.
  8. ↑ Voulgari, C.; Tentolouris, N. (2009). "Assessment of the Spatial QRS-T Angle by Vectorcardiography: Current Data and Perspectives". Current Cardiology Reviews. 5 (4): 251–262. doi:10.2174/157340309789317850. PMC   2842956 . PMID   21037841.
  9. 1 2 Scherptong, R.; Man, S.; Le Cessie, S.; Vliegen, H.; Draisma, H.; Maan, A.; et al. (2007). "The spatial QRS-T angle and the spatial ventricular gradient: Normal limits for young adults". 2007 Computers in Cardiology. Vol. 34. pp. 717–720. CiteSeerX   10.1.1.413.6240 . doi:10.1109/cic.2007.4745586. ISBN   978-1-4244-2533-4. S2CID   143463.{{cite book}}: |journal= ignored (help)
  10. ↑ Rautaharju, P.; Ge, S.; Nelson, J.; Marino Larsen, E.; Pasaty, B.; Furbery, C.; et al. (2006). "Comparison of mortality risk for electrocardiographic abnormalities in men and women with and without coronary heart disease (from the Cardiovascular Health Study)". American Journal of Cardiology. 97 (3): 309–15. doi:10.1016/j.amjcard.2005.08.046. PMID   16442387.
  11. 1 2 Kors, J.; Kardys, I.; van der Meer, I.; van Herpen, G.; Hofman, A.; van der Kuip, D.; et al. (2003). "Spatial QRS-T Angle as a Risk Indicator of Cardiac Death in an Elderly Population". Journal of Electrocardiology . 36: 113–114. doi:10.1016/j.jelectrocard.2003.09.033. PMID   14716610.
  12. 1 2 Rautaharju, M.; Kooperberg, C.; Larson, J.; LaCroix, A. (2006). "Electrocardiographic Predictors of Incident Congestive Heart Failure and All-Cause Mortality in Postmenopausal Women: The Women's Health Initiative". Circulation. 113 (4): 481–489. doi: 10.1161/circulationaha.105.537415 . PMID   16449727.
  13. 1 2 Dilaveris, P.; Gialafos, E.; Pantazis, A.; Synetos, A.; Triposkiadis, F.; Gialafos, J. (2001). "The spatial QRS-T angle as a marker of ventricular repolarization in hypertension". Journal of Human Hypertension. 15 (1): 63–70. doi:10.1038/sj.jhh.1001129. PMID   11224004. S2CID   22455249.
  14. ↑ Man, S.; Rahmattulla, C.; Maan, A.; Holman, E.; Bax, J.; van der Wall, E.; et al. (2012). "Role of the vectorcardiogram-derived spatial QRS-T angle in diagnosing left ventricular hypertrophy". Journal of Electrocardiology . 45 (2): 154–160. doi:10.1016/j.jelectrocard.2011.10.001. PMID   22074745.
  15. ↑ Stein, Paul & Simon, Armando P. vectorcardiographic diagnosis of diaphragmatic myocardial infarction. The American Journal of Cardiology, 1976, 38, 568-574.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.