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Biomedical subjects

D G Pennington

Publications and source records attributed to D G Pennington.

At least 19 recordsLinked to original sources
PubMed2006

Flap-in-flap method for enhancing the advancement of a V-Y flap.

The V-Y principal is used in a number of flap reconstruction techniques. V-Y flaps suffer from design problems of the advancing edge, which is usually concave, trying to match another concave edge on the opposite side of the defect. The flap-in-flap technique uses a second V-Y flap at the advancing edge of the main flap to overcome this mismatch, and also improves the amount of advancement possible. The technique has been used in three patients, demonstrating reliability and a further advantage, which is the ability of the second flap to rotate at an angle to the main flap to aid in reconstructing a complex defect such as the alar base of the nose. Further experience with this technique should widen its applications.

Aged↗
PubMed2002

The microvascular augmented subdermal vascular network (ma-SVN) flap: its variations and recent development in using intercostal perforators.

In 1994 we reported the use of the microvascular augmented occipito-cervico-dorsal 'super-thin' flap for reconstruction of the cervical region in three cases. Since this preliminary report, we have performed a further 17 flaps, and the usefulness of the flap in the treatment of anterior cervical scar contractures in extensively burned patients has become apparent. Moreover, we have devised flaps with not only a narrow skin pedicle but also myocutaneous or island vascular pedicles. Various augmentation vessels, including myocutaneous perforators of the intercostal spaces in the back and chest, have also been used successfully. Here, we describe the microvascular augmented subdermal vascular network flaps that we have devised.

Adolescent↗
PubMed2002

An anatomical and clinical study of the dorsal intercostal cutaneous perforators, and application to free microvascular augmented subdermal vascular network (ma-SVN) flaps.

We report a two-part anatomical and clinical study whose aim was to map the dominant dorsal intercostal cutaneous perforators (DICPs), which are useful for microvascular augmentation of flaps raised from the skin of the back called subdermal vascular network (SVN) flaps, and to test their reliability in the clinical setting. In the anatomical arm of the study, using preserved cadavers, we macroscopically confirmed the location of DICPs, and performed micro-angiography of the dorsal skin to find each dominant DICP. In the clinical arm of the study, we confirmed the location of the dominant DICP during microvascular augmented SVN flap transfer. Postoperatively, posteroanterior radiographs of the chest were taken to locate vessel clips used to ligate the DICPs. The combined study results showed that the dominant DICP is the sixth or seventh in most instances, but there are some anatomical variations. If no dominant DICP is found in the sixth or seventh spaces, at least one DICP that is of sufficient calibre for microvascular augmentation can usually be found in the general vicinity, such as the fifth, eighth or ninth spaces. The clinical application of microvascular augmented SVN flaps, both pedicled and free, is presented.

Adult↗
PubMed2001

Mechanical circulatory support for acute heart failure.

Circulatory support devices are frequently required in postcardiotomy shock, postmyocardial infarction shock, and acute myocarditis. A panel of cardiac surgeons addressed the use of these devices in 4 patients. Cardiogenic shock after mitral valve replacement was considered best served by a left ventricular assist device (VAD) with apical rather than atrial cannulation. A left VAD should be placed first and a right VAD only if needed. Acute myocardial infarction shock was considered best treated with a left VAD with left ventricular cannulation to avoid thrombosis. If cardiac transplantation is an option, a long-term device must be considered. Young patients with acute fulminant myocarditis should be implanted with VADs in anticipation of recovery, and transplantation should be delayed. Patients with severe heart failure after coronary bypass grafting were considered best served by an extracorporal membrane oxygenation (ECMO) system or a VAD. Current postcardiotomy survival rates of postcardiotomy patients of 20% to 40% are worthwhile, but can be improved. Temporary devices such as ECMO can be changed to more long-term devices when necessary.

Acute Disease↗
PubMed1999

Permanent ventricular assist device support versus cardiac transplantation.

BACKGROUND: Although cardiac transplantation provides excellent therapy for some patients with terminal heart failure, the results are limited by the scarcity of donor organs, reduced long-term survival, and comorbid conditions. Current experience with temporary left ventricular assist devices suggest that a permanent, totally, or near totally implantable device may be a viable alternative. METHODS: We analyzed data from the 1997 International Society for Heart and Lung Transplantation (ISHLT) Registry and other literature on heart transplantation and compared survival and complication rates with our experience and that of others with temporary ventricular assist devices. From these data, we attempted to identify those patients who would benefit most from permanent left ventricular assist systems (LVASs). RESULTS: Among heart transplant candidates, United Network for Organ Sharing (UNOS) status II, O blood type, weight >180 lb, older age, and preformed antibodies are negative factors for receipt of donor hearts. Of patients transplanted, women and nonwhites have poorer outcomes. Success with wearable LVAS's suggest some of these patients might be better served with an LVAS than with cardiac transplantation. CONCLUSIONS: Because LVAS's could be made readily available without the need for a waiting list, they might compete well with the strategy of cardiac transplantation.

Adult↗
PubMed1998

Video-assisted thoracoscopic ligation of patent ductus arteriosus: safe and outpatient.

BACKGROUND: Minimally invasive techniques for interruption of patent ductus arteriosus have been reported, but are in use at only a few centers. We examined our series of patients who underwent thoracoscopic patent ductus arteriosus ligation. METHODS: We reviewed 59 consecutive patients, age 6 days to 50 years, weighing 640 g to 62 kg, who underwent video-assisted placement of a stainless steel clip across the patent ductus arteriosus. RESULTS: Thirty-eight nonneonates and 21 neonates (18 were < or =1,500 g) underwent video-assisted thoracic surgery for patent ductus arteriosus closure with intraoperative echocardiographic confirmation in nonneonates. There were no residual shunts, transfusions, chylothoraces, or significant pneumothoraces. Four were converted to thoracotomy, 3 for anatomic variances, and 1 for coagulopathy. Thirty-six of 38 nonneonate patients stayed less than 24 hours; 18 were discharged the evening of the operation. Two were admitted, one after thoracotomy, and one for a small mucosal intubation injury. No others required a chest tube. There were two recurrent nerve injuries. All neonates survived, and were extubated. CONCLUSIONS: Video-assisted thoracoscopic ductus closure is a safe, reliable technique and can be performed as an outpatient procedure in nonneonate patients.

Adolescent↗
PubMed1998

Long-term mechanical circulatory support system reliability recommendation: American Society for Artificial Internal Organs and The Society of Thoracic Surgeons: long-term mechanical circulatory support system reliability recommendation.

Jointly developed by members of the American Society for Artificial Internal Organs and the Society of Thoracic Surgeons along with staff from the Food and Drug Administration, the National Heart, Lung and Blood Institute and other experts, this recommendation describes the reliability considerations and goals for Investigational Device Exemption and Premarket Approval submissions for long-term, mechanical circulatory support systems. The recommendation includes a definition of system failure, a discussion of an appropriate reliability model, a suggested in vitro reliability test plan, reliability considerations for animal implantation tests, in vitro and animal in vivo performance goals, the qualification of design changes during the Investigational Device Exemption clinical trial, the development of a Failure Modes Effects and Criticality Analysis, and the reliability information for surgeons and patient candidates. The document will be periodically reviewed to assess its timeliness and appropriateness within five years.

Animals↗
PubMed1998

Cardiac assist devices.

During the latter half of the twentieth century, physicians have had the capability to support the circulation with mechanical devices. This article gives an historical overview of those devices. Various devices and their complications are described and evaluated. Patient selection and clinical results also are discussed.

Adult↗
PubMed1998

Parental units?

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Surgery, Plastic↗
PubMed1998

Are efforts at expanding the donor pool misdirected?

BACKGROUND: The number of patients potentially benefiting from heart transplantation far exceeds the number of hearts available. This has led to an increasing interest in use of hearts from previously unacceptable donors. However, the long-term outcome of such hearts is largely unknown. Research on other parts of the donor process may provide a greater number of additional hearts of high quality. METHODS: Journal reviews were conducted to identify proposed methods for use of previously unacceptable donor hearts, as well as research regarding the consent process. Data from the United Network for Organ Sharing were obtained to identify the reason consented heart referrals were not recovered. Data from the Association of Organ Procurement Organizations were obtained for consent rates in the United States. Calculated estimates were made for the number of excess hearts potentially available by use of extended donor criteria versus increasing the consent rate. RESULTS: More than 40 articles proposing extended donor criteria were identified versus only 12 articles about consent. Of the 2199 consented heart referrals not recovered in 1995, more than 1300 fit into a category amenable to a proposed strategy for use of extended donors. If these strategies were used aggressively (50% of the time), 701 additional hearts would have been available. Alternatively, if the consent rate were increased a comparable amount, 1260 excess hearts of high quality would have been available. CONCLUSION: Although research into extended donor criteria is probably justified, transplantation programs should direct research efforts into the consent process as a potential source of additional hearts.

Heart Transplantation↗
PubMed1997

Preoperative and postoperative comparison of patients with univentricular and biventricular support with the thoratec ventricular assist device as a bridge to cardiac transplantation.

OBJECTIVES: The goal of this study was to determine whether there are differences in populations of patients with heart failure who require univentricular or biventricular circulatory support. METHODS: Two hundred thirteen patients who were in imminent risk of dying before donor heart procurement and who received Thoratec left (LVAD) and right (RVAD) ventricular assist devices at 35 hospitals were divided into three groups: group 1 (n = 74), patients adequately supported with isolated LVADs; group 2 (n = 37), patients initially receiving an LVAD and later requiring an RVAD; and group 3 (n = 102), patients who received biventricular assistance (BiVAD) from the beginning. RESULTS: There were no significant differences in any preoperative factors between the two BiVAD groups. In the combined BiVAD groups, pre-VAD cardiac index (BiVAD, 1.4 +/- 0.6 L/min per square meter, vs LVAD, 1.6 +/- 0.6 L/min per square meter) and pulmonary capillary wedge pressure (BiVAD, 27 +/- 8 mm Hg, vs LVAD, 30 +/- 8 mm Hg) were significantly lower than those in the LVAD group, and pre-VAD creatinine levels were significantly higher (BiVAD, 1.9 +/- 1.1 mg/dl, vs LVAD, 1.4 +/- 0.6 mg/dl). In addition, greater proportions of patients in the BiVAD groups required mechanical ventilation before VAD placement (60% vs 35%) and were implanted under emergency conditions than in the LVAD group (22% vs 9%). The survival of patients through heart transplantation was significantly better in patients who had an LVAD (74%) than in those who had BiVADs (58%). However, there were no significant differences in posttransplantation survival through hospital discharge (LVAD, 89%; BiVAD, 81%). CONCLUSION: Patients who received LVADs were less severely ill before the operation and consequently were more likely to survive after the operation. As the severity of illness increases, patients are more likely to require biventricular support.

Heart Transplantation↗
PubMed1996

Extended support with permanent systems: percutaneous versus totally implantable.

Use of circulatory support devices in patients awaiting heart transplantation has provided information about the long-term use of these devices. The Novacor left ventricular assist system has proved reliable for long-term support. The main problems with its use are infection and thromboembolism, but neither seems to prohibit long-term use. Problems with compliance chambers are not as great as previously thought. These results suggest that implantation of a permanent, totally implantable left ventricular assist device in lieu of transplantation is feasible.

Animals↗
PubMed1996

Effect of triiodothyronine on graft function in a model of heart transplantation.

BACKGROUND: Brain death is associated with neuroendocrine changes that result in impaired metabolism, reduced myocardial energy stores, and deteriorating cardiac function. As a result of these changes, a substantial number of normal human hearts are not considered suitable for transplantation. In the hope of preventing these complications and stabilizing the condition of cardiac donors, we compared the function of transplanted hearts from brain-dead rats that received triiodothyronine (T3) (n = 6) with that of hearts from a group that received a placebo (n = 5). METHODS: This experiment was designed to be both blinded and randomized. Brain death was achieved by bilateral carotid ligation and inflation of an intracranial balloon. Triiodothyronine or placebo was administered in a blinded, randomized fashion. The brain-dead donors were then supported with conventional techniques for 2 hours after which time heterotopic transplantation was performed using hypothermic preservation and a working heart model. Hemodynamics of the transplanted hearts were assessed 48 hours postoperatively. RESULTS: The hearts from donors that had been pretreated with T3 were found to have a significantly higher (p < 0.005) peak left ventricular pressure than the hearts from the placebo-treated group (137 +/- 17 mm Hg versus 115 +/- 15 mm Hg). Left ventricular end-diastolic pressure was significantly lower (p < 0.01) in the T3-treated group (5.2 +/- 2.2 mm Hg) compared with the placebo-treated group (6.9 +/- 0.5 mm Hg). There was also a significantly higher (p = 0.03) maximal first derivative of left ventricular pressure in the T3-treated group compared with the placebo-treated group (4,876 +/- 1,348 mm Hg/s versus 3,344 +/- 1,016 mm Hg/s). Finally, the cardiac output in the group given T3 was 93 +/- 16 mL/min compared with 61 +/- 22 mL/min in the group given the placebo (p < 0.01). CONCLUSIONS: Hearts from brain-dead rats that had received T3 before transplantation showed improved postoperative function. The experimental design of predonation brain death, cold immersion storage, and transplantation in a working heart model should make these data more relevant clinically than those previously reported.

Abdomen↗
PubMed1996

Secondary sternal repair following median sternotomy using interosseous absorbable sutures and pectoralis major myocutaneous advancement flaps.

A consecutive series of 19 patients were treated for median sternotomy dehiscence by secondary sternal closure with interosseous absorbable sutures and superimposed pectoralis major myocutaneous advancement flaps. These patients were selected for this treatment only on the basis of the quality and quantity of remaining bone stock after debridement. Using this technique there have been no failures of primary therapy with a zero 30-day mortality rate. All patients have achieved good functional and aesthetic results with mechanically stable sternums, wounds confined to the chest and elimination of sepsis. This technique has the advantages of being simple, safe and relatively quick and avoids many of the inherent complications and disadvantages of other techniques and flaps commonly used in the management of this complication.

Adult↗
PubMed1996

Gore-Tex patch repair of the anterior rectus sheath in free rectus abdominis muscle and myocutaneous flaps.

Reconstruction of the breast and other tissues by the free transverse rectus abdominis myocutaneous (TRAM) flap is an accepted, reliable technique with a high success rate. Closure of the anterior rectus sheath defect that results from this flap and the related rectus abdominis muscle-only (RAM) free flap has been the subject of debate, since hernia formation is considered a risk. Some authors prefer direct closure, while others recommend a variety of synthetic mesh reinforcements. We have reviewed 81 patients from a consecutive series of free TRAM and RAM flaps performed by one surgeon (Pennington) over an 8-year period. The majority of patients had repair of the anterior rectus sheath with a 1-mm-thick synthetic patch of polytetrafluoroethylene (Gore-Tex), used in 52 of 71 patients having the TRAM flap and 4 of 10 patients having the RAM flap. There were 5 wound infections (6.2 percent) overall, 3 of which occurred in the Gore-Tex group (5.4 percent). In all 3 of the latter patients, Gore-Tex was removed, although usually only after some months. Even after patch removal, no hernias developed subsequently. The two other infections occurred in patients with a Prolene mesh patch and no patch, respectively. One hernia was found in 71 patients with TRAM flaps, and that was in a patient in whom no patch was used. No hernias occurred in 52 TRAM flap patients with Gore-Tex patches. Hernia formation was noted in 6 of 10 RAM flap patients, although only 1 hernia occurred in the 4 patients with Gore-Tex patches. We conclude that the 1-mm polytetrafluoroethylene (Gore-Tex) patch is a satisfactory method for repair of the anterior rectus sheath after harvesting of either free RAM or TRAM flaps. Even if removal of the patch is required because of infection, the risk of subsequent hernia formation appears minimal.

Abdominal Muscles↗