Biomedical subjects

George Papanicolaou

Publications and source records attributed to George Papanicolaou.

3 recordsLinked to original sources

PubMed2005

Sternal wound reconstruction with transverse plate fixation.

BACKGROUND: Although sternal wound infections and nonunions affect only a small percentage of patients undergoing median sternotomy, the morbidity, mortality, and expenses associated with them continue to make their treatment of great importance. METHODS: The authors present a retrospective study of their experience using titanium plates for repair of 50 complicated sternal wounds. The cases reviewed include all cases performed by the primary and secondary authors between the years of 1998 and 2002. Synthes 2.4-mm locking reconstruction plates were used in transverse fixation across the sternum in conjunction with simple bilateral pectoralis advancement flaps for repair of sternal wound dehiscence, osteomyelitis, and nonunion after median sternotomy. RESULTS: All patients who received treatment were healed. All but one patient went on to complete bony union. Only one case was identified in which a patient developed recurrence of infection around a plate as a late complication 3.5 years later. There were no deaths. CONCLUSIONS: Transverse plate fixation of the sternum in conjunction with simple bilateral pectoralis advancement flaps is a safe and effective means of treating complicated sternal wounds. The benefits of this procedure over standard muscle flap reconstruction include earlier extubation, a tension-free repair with faster and more reliable healing, and a simpler flap technique without the need for turning the pectoral muscle over or dividing it from its origin. The authors believe that this technique is safe and easy to perform and that it may become the standard for sternal reconstruction in the future.

Aged↗

PubMed2002

Reducing the vascular delay period in latissimus dorsi muscle flaps for use in cardiomyoplasty.

Although the mechanism by which vascular delay benefits skin flaps is not completely understood, this topic has been extensively studied and reported on in the literature. In contrast, little has been documented about the effects of vascular delay in skeletal muscle flaps. Recent animal studies tested the effectiveness of vascular delay to enhance latissimus dorsi muscle flap viability for use in cardiomyoplasty and found that it prevented distal flap necrosis. However, these studies did not define the optimal time period necessary to achieve this beneficial effect. The purpose of this study was to determine how many days of "delay" can elicit the beneficial effects of vascular delay on latissimus dorsi muscle flaps. To accomplish this, 90 latissimus dorsi muscles of 45 male Sprague-Dawley rats were randomly subjected to vascular delay on one side or a sham procedure on the other. After predetermined delay periods (0, 3, 7, 10, and 14 days) or a sham procedure, all latissimus dorsi muscles were elevated as single pedicled flaps based only on their thoracodorsal neurovascular pedicle. Latissimus dorsi muscle perfusion was measured using a Laser Doppler Perfusion Imager just before and immediately after flap elevation. The muscles were then returned to their original vascular beds, isolated from adjacent tissue with Silastic film, sutured into place to maintain their original size and shape, and left there for 5 days. After 5 days, the latissimus dorsi muscle flaps were dissected free, scanned again (Laser Doppler Perfusion Imager-perfusion measurements), and the area of distal necrosis was measured using digitized planimetry of magnified images. The authors' results showed that delay periods of 3, 7, 10, and 14 days significantly increased (p < 0.05) blood perfusion and decreased (p < 0.05) distal flap necrosis when compared with sham controls. On the basis of these findings, the authors conclude that in their rat latissimus dorsi muscle flap model the beneficial effects of vascular delay are present as early as 3 days. If these findings also hold true in humans, they could be useful in cardiomyoplasty by allowing surgeons to shorten the amount of time between the vascular delay procedure and the cardiomyoplasty procedure in these very sick patients.

Animals↗

PubMed2002

Super-resolution in time-reversal acoustics.

The phenomenon of super-resolution in time-reversal acoustics is analyzed theoretically and with numerical simulations. A signal that is recorded and then retransmitted by an array of transducers, propagates back though the medium, and refocuses approximately on the source that emitted it. In a homogeneous medium, the refocusing resolution of the time-reversed signal is limited by diffraction. When the medium has random inhomogeneities the resolution of the refocused signal can in some circumstances beat the diffraction limit. This is super-resolution. A theoretical treatment of this phenomenon is given, and numerical simulations which confirm the theory are presented.

Acoustics↗