The 1,000th VAD, the great rivalry, and the grand experiment of the Texas Medical Center

Nothing like a good feud to spark competition: First use of the total artificial heart

As a native Houstonian, the notoriety surrounding Dr. Denton A Cooley's implantation of the total artificial heart on Good Friday, April 4, 1969, was inescapable. At the time, Drs. Cooley and Michael E. DeBakey were the two most famous surgeons in Houston and much of the world. They had worked together professionally for 18 years, revolutionizing cardiothoracic surgery and mastering aortic surgery from beginning to end. However, this working relationship ended abruptly, and one of the most famous feuds in medicine began. Little did I know at the time that I would train with both men, work in both their respective institutions (which are located on the most competitive block of the Texas Medical Center), and play a role four decades later as their relationship rekindled. Here, I recount what I have come to learn about these events.

Honoring 50 Years of Clinical Heart Transplantation in Circulation

Heart transplantation has become a standard therapy option for advanced heart failure. The translation of heart transplantation from innovative experiments to long-term clinical success has married prescient insights with discipline and organization in the domains of surgical techniques, organ preservation, immunosuppression, organ donation and transplantation logistics, infection control, and long-term graft surveillance. This review explores the key milestones of the past 50 years of heart transplantation and discusses current challenges and promising innovations on the clinical horizon.

High-speed visualization of disturbed pathlines in axial flow ventricular assist device under pulsatile conditions

OBJECTIVE

To investigate potentially prothrombotic flow patterns within an axial flow ventricular assist device under clinically relevant pulsatile hemodynamic conditions.

METHODS

A transparent replica of the HeartMate-II left ventricular assist device (Thoratec, Pleasanton, Calif) was visualized using a high speed camera at both low and high frame rates (125 and 3000 fps). Three steady-state conditions were studied: nominal (4.5 lpm), low flow (3.0 lpm), and high flow (6.0 lpm). Time-varying conditions were introduced with an external pulsatile pump that modulated the flow rate by approximately ± 50% of the mean, corresponding to a pulsatility index of 1.0.

RESULTS

At nominal and high flow rates, the path lines within the upstream region were generally stable, well attached, and streamlined. As the flow rate was reduced below 3.8 lpm, a rapid transition to a chaotic velocity field occurred, exhibiting a large toroidal vortex adjacent to the upstream bearing. The pathlines in the downstream stator section were consistently chaotic for all hemodynamic conditions investigated. It was common to observe tracer particles trapped within recirculation bubbles and drawn retrograde, causing repeated contact with the bearing surfaces. The addition of pulsatility caused the flow field to become periodically chaotic during the diastolic portion of the cardiac cycle depending on the instantaneous flow rate and acceleration.

CONCLUSIONS

The contribution of pulsatility by the native heart may induce a periodic disturbance to an otherwise stable flow field within an axial flow ventricular assist device, particularly during the diastolic and decelerating portion of the cardiac cycle. Potentially prothrombotic flow features were found to occur periodically in the region of the upstream bearing.