Saadat Dena 640 User Manual page 30

A common method among physician for heart axis calculation is iso-electric method. Iso-electric lead
for QRS complex is a lead which the collection of Q, R and S complex amplitudes is near to zero. In
this situation, the direction of heart axis will be perpendicular to direction of iso-electric vector. Any
combination of 2 limb leads can be used to calculate the electrical axis of heart. Some of well-known
equations to calculate the heart axes are provided in the following table.
Selected Leads
In these equations, "I" is the net amplitude of QRS complex in lead I and "II" is the net amplitude of
QRS complex in lead II. So based on researches done, using the lead with the maximum net amplitude
makes the results more accurate. In DENA electrocardiograph system, the combination of 2 leads with
highest amplitude is used to calculate the heart axis according to the equations defined in the above
table.
Saving
Enabling "Save" option on the memory menu, all data recorded in Rhythm and Auto modes is saved in
the internal memory which can be achieved to them if necessary. The maximum capacity of internal
memory is 100 records. As memory is full, the oldest data will be replaced the new data automatically.
The records saved on "Show Records Menu" is displayed in figure 2-15. These records can be searched
by Name and ID. Choosing any record, its specification and signal morphology will be displayed.
This feature is illustrated in the fifth section completely.
I aVF
and
I II
and
�� ������
and
II III
and
Records saved on " Show Records Menu"
Equation
−1
�� = ������ (2������/ 3 ��
−1
�� = ������ ((2���� − ��)/ 3 ��
−1
�� = ������ ((�� + 2������)/ 3 ��
−1
�� = ������ (
Figure 2-15
24
)
���� + ������
)
3 ���� − ������