Abstract: An inflow conduit of a ventricular assist device configured to prevent formation of recirculation and stagnation zones as well as collapse due to external forces or pump induced suction can be rigid and have a funnel like shape with an elbow to accommodate a patient anatomy. Stiffening elements and pressure sensing devices can also be provided associated with the inflow conduit.

Abstract: A heart rate detector apparatus, particularly for use in an implantable defibrillator, is disclosed. The heart rate detector apparatus includes two distinct detector circuits each responsive to ECG waveforms of different characteristics. One of the detector circuits is responsive to ECG waves having slew rates above a predetermined threshold. The other detector circuit is responsive to ECG waves having lower slew rates, such as ECG waves of more sinusoidal shape. A coupling circuit automatically couples one of the two detector circuits to an output circuit, such as a heart rate comparator. In a specific embodiment, the heart rate comparator determines the heart rate, compares the heart rate with a predetermined rate, and, if the heart rate exceeds the predetermined rate for a predetermined time period, provides an output signal. The output signal may be used to enable a defibrillating circuit to deliver a defibrillating shock to the patient.

Abstract: A method and apparatus for effecting automatic ventricular defibrillation and/or demand cardioversion comprises an implanted automatic defibrillator having a normal (ventricular defibrillation) mode of operation and a cardioverting (demand cardioversion) mode of operation. One embodiment of the invention includes a simulated fibrillation source, externally located, for applying a simulated fibrillation signal to the patient via corresponding electrodes, the internal automatic defibrillator detecting the simulated fibrillation signal and responding thereto so as to apply a defibrillating voltage (in the normal mode) or a cardioverting voltage (in the cardioverting mode) to the heart of the patient. Another embodiment of the invention also includes an external command system, by means of which the implanted automatic defibrillator is actuated from the normal mode to the cardioverting mode, to reduce the discharge energy level, to cardiovert in synchronization with the QRS complex, or both.