Heart failure is a growing epidemic within the global population, with an estimated 64.3 million people living with the condition as of 2017, with up to 45% of patients dying within a year of their first hospital admission. For the most severely affected patients, a heart transplant is considered to be the preferred method of treatment. However, there is a scarcity of hearts available for treating each patient that presents, with transplant waiting lists growing year-on-year. In order to combat this, mechanical alternatives to the natural heart, such as ventricular assist devices, total artificial hearts and extra-corporeal membrane oxygenation, have been developed to relieve the patient burden on the healthcare system. The cost of these devices, however, remains high and often treatment exhibits a poor economic case, particularly for short-term support periods. As a result of this, development of a lower-cost alternative device is paramount to improve cost-effectiveness within healthcare for severe heart failure. In previous decades, one of the most prevalent devices was the Intra-Aortic Balloon Pump (IABP), which saw relative success due to being easy to insert, low development and equipment costs and increased accessibility in comparison to other mechanical circulatory support devices. It acts as a volume-displacement device inside of the patient's aorta, inflating during diastole (the heart's relaxation period) to increase circulatory energy. However, the low haemodynamic support provided by IABP and lack of randomized controlled trial evidence suggesting significant patient benefit, has seen its use decline across the past decade. Throughout the timeline of IABP usage, a number of attempts have been made to translate the balloon volume-displacement concept into a device that pumps blood from inside of the ventricle, known as an Intra-Ventricular Balloon Pump (IVBP). Each of these studies demonstrated successful increases in cardiac output and arterial pressure resulting from IVBP; however, the concept never progressed beyond early prototyping and evaluation. No specific reasoning was provided for these previous cessations in research; however, the concept is once again the subject of fresh interest, with as many as four research groups publishing on the concept since 2018. This present study aimed to continue the development of an IVBP prototype device for use as short-term mechanical circulatory support. A primary focus was placed onto evaluating physiological compatibility of the IVBP to provide beneficial support for the patient, with a view to evaluation of risk of mitral valve regurgitation, haemolysis, thrombosis and arrythmia. It was hypothesised that the usage of IVBP would increase the amount of support provided to the circulation without inducing excessive haemolysis and thrombosis, and without induction of mitral valve prolapse, leading to regurgitation. [...]