Cardiogoniometry

In Germany, every day approximately 10,000 people are admitted to the hospital with a suspected myocardial infarction. Although this diagnosis will be confirmed in only 8% of the cases, acute myocardial infarction is still one of the most common causes of death.

The highest chance to survive an infarction is a speedy diagnosis so appropriate treatment can be initiated. “Cardiogoniometry” (CGM) is a new method with which a hidden infarction can be detected within seconds.

Swiss physician Dr. Ernst Sanz developed this diagnosis based on vectorcardiography, which is the basis of enverdis’ CARDIOLOGIC EXPLORER. enverdis has developed this device, during years of extensive research, which offers an immediate and straight forward application.

Cardiogoniometry Is a New Stress-Free, Non-Invasive Diagnostic Procedure

The electrical activity of the heart is displayed three-dimensionally within 12 seconds using five electrodes. The test takes place in a resting position. There is no requirement for a stress ECG . The computer instantly interprets the data and the readings are available immediately following the test. Therefore, the patient and the medical professional receive feedback without delay, enabling the doctor to spot an infarction right away.
CGM provides a three-dimensional display of the heart’s activity which is more precise than the classic ECG.
In addition, impaired circulation of the heart, often the precursor of an infarction, can be diagnosed completely stress-free.

 

The Original Vectorcardiography

Since the introduction of electrocardiography, the term “electrical axis” has been used. Within a normal cardiac cycle excitation, during the peak of the R wave, a comparatively strong electrical force becomes evident, which is directed toward the cardiac apex. This can be marked in “Einthoven’s Triangle” as the “electrical axis of the heart” – or “electrical axis of the R wave” to be more precise. The three characteristics: size (length), direction (position within coordinate system), and polarity, mark the physical definition “vector”.

The chronological resultant force of the bio-electrical forces (momentum vectors) can be marked in the Einthoven’s Triangle with arrows, connecting the arrow tips. Thereby, a coherent ansiform line emerges, which represents the vectorcardiogram (VCG). This is labelled the geometric position of the endpoints of the individual current vectors on the frontal-plane. The vectorcardiogram specifies in which direction and at what intensity the activation takes place at any given point.

Electrode Diagram and Orthogonal Leads

Mechanical heart activities are based on the conduction of electrical impulses resulting in measurable potentials. These potentials are captured and converted into digital values using bipolar leads (A, D, and Ve). For data recording, in addition to the ground electrode, only four thoracic electrodes are required, positioned in a predefined geometric configuration. The particular electrode positioning provides a three-dimensional reading and spatial display of the cardiac potentials over a specific period of time.

Diagram and data recording

Conditions for the Placement of Electrodes

Distance between

are in mutual orthogonal configuration

The application of the electrodes

Transformation of Leads and Displays

The data gathered from A, D and Ve is summarized vectorially and analyzed as a three-dimensional time signal. Although the leads are in a fixed geometric configuration, for physiological reasons, it is not orthogonal. Transformation of the data supplied by leads A, D and Ve to X, Y and Z convert the digitalized data into an orthogonal form, whereby X and Y represent the diagonal sagittal plane and Z runs orthogonally to the sagittal plane.
With these three leads in an orthogonal configuration, it is now possible to build a three-dimensional vector display.
This offers a considerably more realistic visualization of cardiac conduction stimuli processes than has previously been possible in vectorcardiography.

Transformation of the bipolar derivation into the orthogonal derivation/axes X, Y and Z

X=D * sin(45°)-I
Y=D * sin(45°)+A
Z=sin(45°)(Ve-Ho)

Difference Between Cardiogoniometry and Conventional Vectorcardiography

In conventional vectorcardiography (VCG), the projected vector planes are aligned to the body axis: horizontal, vertical and sagittal. The result of this is that the anterior and posterior walls of the heart are partially superimposed and the observer requires good visual thinking to understand the orientation of the vector loops.

In cardiogoniometry, the major planes are rotated by 45 degrees in the major axis of the heart. This way, the heart is split into the anterior and posterior walls, which provides a better insight into the vector loop formation, which normally lies in the diagonal sagittal plane. The diagonal sagittal plane thus becomes the main plane.

Planes in traditional vectorcardiography
Planes and axes in Cardiogoniometry

Spatial Loops and Maximum Vectors

Following the digitisation and conversion of data to the X, Y and Z axes, a vector (x,y,z) defines through its direction and the orientation of the current summation potential for each time point t. For illustration purposes, these vectors can be displayed as a loop in a three-dimensional coordinate system. Each vector originates from an isoelectrical coordinate origin and is directed towards a particular point in the spatial matrix. The individual points are chronologically connected to build a loop.

Development of a single point on the loop from all channels X,Y and Z at timepoint t
Formation of the loop over time and determination of maximum vectors (red)

Diagnostic Criteria

In ECG, signs of existing myocardial ischemia are apparent in the repolarization phase in ST depression (STT segment) and changes in depolarization (QRS segment) only occur in the presence of myocardial damage (infarction).

This is also the case in CGM. After many years of research and trials in over 700 patients, it has been possible to draw up the following ten working conclusions:

Conclusions for R (QRS Complex)

  1. The summation potential of R (=SumR) is an indication of the vital myocardial mass.
  2. Rmax indicates the location of the maximum of this mass.
  3. The extent of floating of Rmax or the R loop correlates with the extent of homogeneity of the myocardium.
  4. Moderate floating of Rmax is attributable to respiration.
  5. Extreme floating = fresh infarction

Conclusions about T (STT Complex)

  1. The summation potential of STT (=SumSTT) is an indication of the extent of perfusion of the myocardium.
  2. Tmax indicates the location of the perfusion maximum.
  3. The extent of floating of Tmax or of the T loop correlates with the extent of homogeneity of the blood supply.
  4. Moderate floating of Tmax is attributable to technical factors or respiration.
  5. Extreme floating = manifest ischemia

These conclusions are provided to facilitate the diagnosis and the evaluation of clinical findings.

Three-Dimensional Loop Display

In CGM, deviations from the typical stimulus conduction profile are mainly indicated as changes in the direction of maximum vectors. Therefore, the spatial orientation of these vectors and their angles relative to on another are particularly sensitive indicators in the detection of myocardial ischemia.
Reference ranges have been defined for the absolute orientation of these maximum vectors. If the spatial orientation of these maximum vectors is outside the reference ranges, this indicates a pathological situation.

Healthy: The maximum vectors (orange) of the T-loop (green) and R-loop (blue) of the different beats point towards the apex of the heart. The loops overlap and lie homogenously over each other.
Vectorloop sick patient
Pathological: The maximum vectors (orange) of the T- and R-loops do not point towards the apex of the heart. The loops have a heterogeneous course.

The 3D loop display of the CGM software also provides the option of displaying reference ranges and maximum vectors. The full display can be moved freely in any direction, it can be rotated or magnified with a mouse. This offers the user the best possible dimensional image of the status of cardiac conduction stimulation. In addition it can quickly be assessed whether the maximum vectors of the loops are within reference ranges and whether they exhibit a low degree of floating (both of which indicate normal findings).

The Transparent Heart

In the display option “loop 3D”, the heart on the left side of the loops is shown transparent. The position of the three-dimensional heart may be interchanged with the loops. This way, the entire transparent heart can be scaled, rotated or magnified. Furthermore, this display function offers the possibility, if areas of ischemia are localized, to show them as dark structures in the transparent heart.

The transparent heart showing the localisation of an ischemic area

Projection of Maximum Vectors

The spherical coordinate system is used to detect and analyze the direction of the maximum vectors. The point of intercept between vectors and sphere is defined in terms of longitude (alpha) and latitude (beta).
The basal hemisphere is folded outwards (similar to an opened globe), illustrating the localization of vectors running in a basal direction. This display option allows to capture the position and distribution of maximum vectors at a glance.

Octant configuration in the maximum vector display, the cardiac apex is located in the center of this view, whereas the basal hemisphere is folded outwards
Healthy: The maximum vectors of R and T (depolarisation and repolarisation) are located close together and within the standard area. This is indicative of healthy formation of potential.
Pathological: The maximum vectors of R and T are not pointing towards the cardiac apex. The loops run heterogeneously (scattered), indicating acute ischemia. The R maximum vectors are clearly located outside of the standard area and are clearly scattered. This indicates an acute infarction in the inferior septal region of the left ventricle.

Blue field:             Reference range for maximum vector of R
Green field:          Reference range for maximum vector of T
Blue Squares:      Maximum vectors of R for individual heart beats
Green Triangles:  Maximum vectors of T for individual beat beats

(Yellow – selected individual heart beat, Red – median heart beat)

Automatic Interpretation and Parameters

The CGM software performs an automatic analysis and suggests a diagnosis to the user. In addition to the automatic interpretation option, the user can carry out a manual diagnosis based on the various views and save this within the software.

Healthy: All relevant parameters are within reference ranges.
Pathological: Pathological findings start with the yellow area. Parameters in the red area most likely point to relevant ischemia.

Areas of Application for Cardiogoniometry (CGM)

Myocardial infarction still is the most common cause of death in Germany. Every year more than 60,000 people die from it (Federal Statistical Office, 2008). A cardiac infarction is, however, often preceded by an undetected coronary heart disease. In 50% of the cases the cardiac infarction is the first clinical symptom of a coronary heart disease. Until now, no procedure has been established in a clinical application, which is non-invasive, stress-free, easy to apply and automatically interprets the readings, especially of asymptomatic patients with coronary heart disease (CAD), possibly even as a screening method in the general practioners’ offices. Cardiogoniometry (CGM) can close this gap. It is an automatic procedure for the diagnosis of CAD, myocardial ischemia and myocardial diseases which can be performed on a resting patient within a few minutes.

Clinical trials have been published with approximately 2,000 patients in a range of settings and in comparison to various reference methods (e.g. coronary angiography, cardio-MRI, SPECT). The average sensitivity and specificity of the CGM for the detection of the afore-mentioned disease patterns was approximately 73% for the former and approximately 84% for the latter. Meta-analyses of the Stress ECG reaches a sensitivity of 67% and a specificity of 72% on patients with chronic CAD without a prior myocardial infarction. Further controlled studies determine the significance of CGM in diagnostics, in terms of suspected coronary heart disease as well as an acute coronary syndrome without ST-elevation. Due to the simplicity, cost-efficiency of an automatic analysis as well as a diagnosis without physical or medical stress, this method is primarily suitable for general practioners. In patients with non-specific chest pain, unspecific ECG and not yet existing troponin, a positive CGM substantiates the suspicion of a present acute coronary syndrome. If all three methods of examination are negative, a non-ischemic cause is the possible reason for chest pain. In stable patients with a non-specific or non-performed stress ECG, a positive CGM substantiates the suspicion of coronary heart disease or myocardial diseases.

Options

Assessment of the Cardiogoniogram

  • Three-dimensional assessment of heart potentials
  • Choice of display mode of 3-6 channels in the CGM-writer
  • Online display of the pulse frequency
  • Choice of printing rate (10, 25, 50, 75, 100 mm/s) and enhancement display (5, 10, 15, 20 mm/mV)

Display and Measurement

  • Display of the conduction propagation as three-dimensional loop in three projection planes and transparent heart
  • Display of maximum vectors of R and T loop as well as their normal ranges
  • Display of a chronological progress of the vector potential
  • Automatic determination and display of the median beat in the CGM-writer

Interpretation

  • Automatic measurement and interpretation according to defined parameters
  • Automatic generation of finding

General Functions

  • Collection and saving of manual diagnosis
  • Verification of the test
  • Export of the automatic and manual diagnosis
  • Print of complete report
  • Print of manually chosen display options
  • Print preview of specified screenshots
  • PDF-print available with additional software