An apparatus for measuring cardiac electrical activity of a patient includes: a malleable pad, a first electrocardiogram electrode, and a ground electrode. The pad includes: a right handle for grasping with the patient's right hand, the right handle including an electrocardiogram electrode; a left handle for grasping with the patient's left hand, the left handle also including an electrocardiogram electrode; and an electronic circuit configured for receiving electrical signals from the electrodes and also configured to invert the signals from the electrodes for transmission to a processor to produce a graphic recording of the differences in electrical potential between the electrodes. The pad also includes a multiplex cable for coupling the electronic circuit to leadwires attached to the electrocardiogram electrodes; and a port configured for coupling with the processor. The first electrode and the handle electrodes form an inverted Einthoven triangle with the first electrode at an apex of said triangle, being located anatomically superior to the horizontal axis formed by the second and third electrodes.