Patients awaiting heart transplants can be kept alive with the use of mechanical devices called ventricular assist devices (VADs). VADs are implanted to support the heart's pumping function, improving blood flow and organ function while waiting for a donor heart. These devices serve as a bridge to transplantation, providing critical support if medical therapy alone is insufficient. They help sustain the patient by taking over part or all of the heart's workload and can significantly enhance survival and quality of life during the waiting period. Additionally, during the transplant surgery, heart-lung bypass machines are used to maintain circulation temporarily. Innovative technologies like warm perfusion machines also exist to maintain donor hearts viable for longer periods during transport but relate to donor heart preservation rather than patient support. In summary, the primary means to keep patients alive while waiting for a heart transplant are ventricular assist devices (VADs) and heart-lung bypass machines used during surgery.