Apparatus for checking the contractility of the cardiac muscle; Cardiac catheters; Cardiac fulguration apparatus; Cardiac fulguration electrodes; Cardiac pacemakers; Cardiac pulse generators; Cardiac stimulators; Cardiac valves for surgical prostheses; Cardiac vascular prosthesis for surgical prostheses; Implantable cardiac pulse generators; Instruments for cardiac stimulation; Medical apparatus for use in cardiac surgery; Defibrillator monitors; Defibrillators