Development of the Philadelphia Heart System

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Materials Science

Background:

• Development of artificial heart systems is crucial for treating end-stage heart failure.
• Existing systems often face challenges with blood compatibility and long-term durability.
• Need for integrated, mass-producible artificial hearts that mimic natural cardiac function.

Purpose of the Study:

• To develop and evaluate a novel pneumatic artificial heart system designed for reduced blood trauma and improved manufacturability.
• To assess the system's ability to replicate natural heart pressure and flow waveforms.
• To investigate the biocompatibility and long-term performance of the artificial heart in a preclinical model.

Main Methods:

• Constructed polyurethane ventricles using vacuum-forming and solution-casting.
• Integrated blood pumps and drive systems with permanently attached atrial cuffs and arterial grafts.
• Utilized a drive system producing variable pressure rise (dP/dt) to optimize valve function.
• Implanted the system into 25 calves, including 17 chronic experiments, with St. Jude bileaflet valves in 14 animals.

Main Results:

• Mean survival of 39 days in animals with St. Jude valves, with 6 surviving over 30 days (longest 129 days).
• Postoperative drop in red blood cell count and hematocrit normalized within 3 weeks.
• Plasma free hemoglobin remained below 5 mg/dl; initial renal infarcts were absent in later experiments.
• Pseudoneointimal growth observed on blood-contacting surfaces in long-term survivors, similar to natural tissue response.

Conclusions:

• The novel pneumatic artificial heart system shows potential for reduced blood trauma and improved biocompatibility.
• The design's integration of mass-production techniques and optimized drive system contributes to promising preclinical outcomes.
• Long-term implantation revealed tissue responses comparable to those seen with natural heart valves, warranting further investigation.