This paper presents a remotely powered implantable heart monitoring system for freely moving animals. The system measures the blood pressure in the left ventricle of the heart and transmits the data to a database unit. The implanted unit is remotely powered over 25 mm at 8 MHz and has autonomous power control system for changing received power levels due to the moving animal. The blood pressure is measured by a piezoresistive sensor die. The data is transmitted by a OOK modulated transmitter at 868 MHz. The system is realized by using discrete components which are available on the market. The overall size of the implanted unit is 26x13x5.5 mm and the overall power consumption is around 7 mW. Experimental results show the effectiveness of the implantable monitoring system.