A vector heart is a mathematical representation of the human cardiac cycle. It can be used to study heart rhythms and to design a clinical intervention. Originally, the heart vector was a single, circular shape, but more recent versions include a series of rectangular shapes. A vector heart is an important diagnostic tool, as it allows researchers to visualize heart patterns in complex patient datasets. The software developed by researchers at the University of Illinois is available for free in GitHub.
The vector of the current flow in the heart changes rapidly during each cardiac cycle. This change in direction and voltage is reflected in the electrocardiogram, which is a graphic representation of the heart's electrical potential. Several features are present in this diagram, such as the length of the arrowhead. It's important to remember that the length of the arrowhead corresponds to the potential voltage in the heart. This information helps physicians to accurately predict changes during the cardiac cycle.
The first stage of cardiac repolarization occurs in the left ventricle. A short vector exists, as only a small part of the ventricular muscle is depolarized. The vector is positive at the beginning, but negative later. By the time the vector reaches the midpoint, the entire ventricular muscle mass is depolarized. The voltage in lead II is greater than those of leads I and III, thus the vector is short.
Using the same principles, an averaging network system can be used to obtain the sagittal electrode. The sagittal electrode is effectively more distant from the heart. A symmetrical system based on this principle can provide all three components of the heart vector, which are directly proportional to the voltages of the four bipolar leads. Adjusting the amplifier gain will introduce appropriate weighting factors for the three components of the heart vector.
The first step in learning to read a vector heart is to learn about the QRS and its components. The QRS vectorcardiogram shows the normal heart during depolarization. The vectors are oriented in a preponderant direction, toward the apex of the heart. The electrical potential of the heart travels from the base of the ventricles toward the apex for most of the depolarization cycle.
The second step is to select a pivot point in the centre of the heart. To choose the pivot point, select the rotate tool and use the centre pivot point as its pivot. With the pivot point selected, add a copy of the teardrop shape to the lower part of the heart. This can be done by rotating the pivot point to a 22.5 degree angle. The third step involves arranging the remaining elements of the heart. With these steps, you can create a unique vector heart!
The depolarization process in the atria begins in the sinus node and spreads out over the atria. The sinus node, which enters the atria before the heart, is the point of initial electronegativity. This is represented by the black vector shown in Figure 12-9. The vector of initial depolarization is positive throughout the process of normal atrial depolarization, and the vector of repolarization is negative for the entire atria.
The electrocardiogram also uses the J point as a reference level to detect mild coronary ischemia. An electrocardiogram is not sensitive enough to distinguish between a healthy heart and one with a heart that has undergone a coronary artery occlusion. A simple electrocardiogram can detect mild coronary insufficiency by detecting changes in the T wave. It can also be used to distinguish between an irregular heart rhythm and a cardiac infarction.
When performing an electrocardiogram, lead placement is crucial. A standard bipolar limb lead (advanced on the left in Figure 12-20) and a chest lead (Figure 12-21) are necessary for accurate diagnosis. In the chest lead, a zero potential reference line is drawn from the J point of a lead, which shows the potential current for injury during the T-P interval. The positive and negative ends of the vector point toward the anterior chest wall, respectively.