Biomedical subjects

C Y Ahn

Publications and source records attributed to C Y Ahn.

At least 19 recordsLinked to original sources

PubMed1997

Simultaneous bilateral breast reconstruction with the transverse rectus abdominus musculocutaneous free flap.

OBJECTIVE: The purpose of the study was to assess the results and morbidity associated with simultaneous bilateral TRAM free flap breast reconstruction and describe refinements in its surgical technique. SUMMARY BACKGROUND DATA: Bilateral prophylactic total mastectomies might be an agreeable option for those patients at highest risk for breast cancer if autogenous tissue breast reconstruction could be performed with reasonable technical ease and acceptable morbidity. However, some surgeons harbor reservations regarding the extensiveness of the surgery, the associated morbidity, and the aesthetic quality of the resulting outcome. METHODS: A multicenter retrospective review of clinical experience with 120 consecutive patients who underwent 240 simultaneous bilateral TRAM free flap breast reconstructions was developed. RESULTS: The average operating time, including the time required for the breast ablative portion of the procedures, was 8.6 hours. The average length of hospitalization was 7.6 days. However, for the last 40 patients, these figures were reduced to 7.1 hours and 6.1 days, respectively. Nonautologous blood transfusions were needed in 33 cases (28%), but only 1 was required in the last 40 patients. Thromboses developed in six of 240 flaps (2.5%): 4 were arterial and 2 were venous. Re-exploration allowed us to restore circulation in five flaps, whereas one flap was unsalvageable and was replaced successfully with an alternate flap. An uncomplicated deep vein thromboses developed in one patient with a history of recurrent deep vein thromboses that had no adverse effect on her outcome. Minor complications developed in 18 patients (15%) (e.g., hematoma, partial wound necrosis, wound infection, or prolonged postoperative ileus) that did not affect the long-term outcome. Fourteen patients (11.6%) had abdominal wall weakness or hernias. Follow-up time averaged 37.2 months (range, 14-62 months). On last follow-up, patients' self-reported overall satisfaction with the procedure was 56% excellent, 40% good, and 4% fair. CONCLUSIONS: Simultaneous bilateral free flap reconstruction is technically feasible with a high rate of success and an acceptable morbidity. When performed by experienced surgeons, bilateral prophylactic total mastectomies combined with simultaneous bilateral TRAM free flap reconstruction may provide an adequate surgical option with aesthetically acceptable results for patients at high risk for breast cancer.

Blood Loss, Surgical↗

PubMed1997

TRAM flaps in patients with abdominal scars.

Of 114 patients who had TRAM flap breast reconstruction, 46 (40 percent) had preexisting abdominal surgical scars. Sixty-six free TRAM flaps and 9 pedicled TRAM flaps were performed in the 46 patients. The records were analyzed to determine what impact, if any, abdominal scars had on postoperative complications. There were no reconstructive failures or significant (>25 percent) flap losses. Eight minor complications occurred in 7 patients (15 percent). The incidences of abdominal-wall weakness (4.3 percent), partial flap loss (4.3 percent), minor fat necrosis (4.3 percent), and donor-site wound problems (4.3 percent) were acceptable. Subcostal scars and multiple abdominal scars were found to predispose to skin complications. Right lower paramedian scars precluded free TRAM flaps because of damage to the inferior epigastric vessels in three of three patients. Both obesity (p = 0.003) and smoking (p = 0.05) were associated with a greater risk of wound-healing complications. We conclude that with certain technical modifications, TRAM flap reconstruction is a safe and effective procedure in patients with abdominal scars.

Cicatrix↗

PubMed1996

Safe ischemia time in free-flap surgery: a clinical study of contact-surface cooling.

Although the effectiveness of cooling in extending tolerable ischemia time is well-established experimentally, most free-flap surgeons are still concerned about this problem and try to limit the ischemic period to less than 1 hr. Clinically, contact-surface cooling has been used empirically to prolong the limits of ischemia time; however, its applications are unproven. It also remains unknown whether contact-surface cooling has detrimental effects on flap tissue, such as vessel spasm leading to thrombosis. The purpose of this study was to determine, in a clinical setting, if skin, muscle, and bone free flaps of considerable size could tolerate prolonged cold ischemia without adverse effects. Flap size, cold ischemia time, and surgical outcomes were studied in 189 consecutive free flaps. Microvascular thrombosis occurred in 5/378 (1.3 percent) of anastomoses. The overall flap complication/flap loss rate was 7/189 (3.7 percent). Mean ischemia time for all flaps was 2 hr and 6 min (range: 30 min to 5 hr, with one case at 6 hr and 8 min). The mean ischemia time for cases with flap complications was 2 hr 20 min, while ischemia time for cases with thrombosis averaged 2 hr 13 min. The one flap loss had an ischemia time of 1 hr 35 min. No statistically significant correlations existed between duration of ischemia time or duration of contact-surface cooling and the incidence of thrombosis, flap complication, or flap failure. Among the conclusions were that, within a 4-hr period of cold ischemia, the application of the surface-cooling technique is not detrimental to free flap surgery; thus, concern for ischemia, and especially the "no reflow" phenomenon, generally should not interfere with efficient and orderly free-flap surgery.

Humans↗

PubMed1996

The use of cryopreserved microvenous allografts in the venous system without immunosuppression: an experimental study.

Autogenous vein grafts are currently the number one choice in microsurgical practice for managing vessel length discrepancies. A significant percentage of these grafts is used in the venous system. Allografts may serve as a viable alternative source of vein grafts. Few studies in the past have described the use of cryopreserved vein grafts (1 mm in diameter) in the venous system. In the present study, we cryopreserved the femoral veins of rats and transplanted these across rat species (ACI to Lewis) as interpositional vein grafts into a defect in the femoral vein. Short-term patencies (21 days), expressions of systemic antigenicity, histology, and scanning electron microscopic studies were performed. We obtained 100% patencies with fresh control veins and cryopreserved veins at 21 days.

Animals↗

PubMed1996

Capsular synovial metaplasia as a common response to both textured and smooth implants.

Recent reports suggested that the presence of synovial metaplasia in the capsular tissues of breast implants is greater with textured-shelled implants compared with smooth. Textured implants, however, have become popular only in the last few years. Therefore, the studies do not address the possibility that synovial metaplasia may be a dynamic process related to time (e.g., implant age) rather than implant shell surface. In the current study, 159 implant capsules (85 patients) removed between February of 1992 and July of 1993 at UCLA Medical Center were evaluated histologically and correlated with clinical data, including the age of implants. Synovial metaplasia was identified in 40 percent (64 of 159) of the capsule specimens. A logistic regression analysis that removed the effect of implant age demonstrated no correlation of implant shell type (textured versus smooth) with the presence of synovial metaplasia. Gel bleed, implant location, pericapsular fluid, implant rupture, and capsular contracture also did not have any significant association with synovial metaplasia in the current study. The incidence of synovial metaplasia appears to decrease with age (77 percent at < 5 years; 22 percent at > 15 years). Our findings suggest that synovial metaplasia is not rare and in fact may be a fairly common transitional histologic finding. It may be part of the common progression that occurs at the implant-capsule interface. The clinical significance remains unknown.

Adult↗

PubMed1996

Microbial evaluation: 139 implants removed from symptomatic patients.

Possible adverse effects of microbial organisms have been implicated in symptomatic silicone implant patients. In the literature, numerous authors have investigated the possible role of infection with respect to implant problems. To date, various bacterial species have been reported, including Staphylococcus aureus, Staphylococcus epidermidis, peptostreptococci, and Clostridium perfringens. Infections in polyurethane-coated prostheses also have been shown to prolong morbidity. Antibiotic use has been relatively empirical in this regard. The purpose of this study was, first, to determine the frequency, type, and clinical relevance of microbial colonization on implant surfaces removed from symptomatic patients and, second, to determine possible effects of microbial colonization on implant integrity (gel bleed, rupture). A total of 139 implants from 72 symptomatic patients were entered into the prospective clinical study between February of 1993 and July of 1994 at the UCLA Medical Center. The implant shell types included smooth (79 percent), polyurethane (8 percent), textured (7 percent), and smooth and Dacron (6 percent). The implant locations were subglandular (71 percent), submuscular (28 percent), and subcutaneous (1 percent). Of the 139 implants removed, 69 percent were intact and 31 percent were ruptured. Forty-seven percent of 139 implants were culture-positive. Propionibacterium acnes was isolated most frequently (57.5 percent), followed by Staphylococcus epidermidis (41 percent), and then Escherichia coli (1.5 percent). No fungal infections were identified. Culture positivity was not significantly associated with systemic symptoms. Sixty-seven percent of the positive culture implants were intact; 33 percent were ruptured. The frequency (47 percent) and types (P. acnes and S. epidermidis) of microbial colonization are determined in symptomatic silicone implant patients.

Adult↗

PubMed1995

Clinical experience with a microvascular anastomotic device in head and neck reconstruction.

BACKGROUND: Despite numerous refinements in microsurgical technique and instrumentation, the microvascular anastomosis remains one of the most technically sensitive aspects of free-tissue transfer reconstructions. MATERIALS AND METHODS: Concurrent with the development of microsurgical techniques, various anastomotic coupling systems have been introduced in an effort to facilitate the performance and reliability of microvascular anastomoses. The microvascular anastomotic coupling device (MACD) studied here is a high-density, polyethylene ring-stainless steel pin system that has been found to be highly effective in laboratory animal studies. Despite its availability for human clinical use over the last 5 years, reported clinical series remain rare. Our clinical experience with this MACD in 29 head and neck free-tissue transfers is reported herein. RESULTS: Thirty-five of 37 (95%) attempted anastomoses were completed with 100% flap survival with a variety of donor flaps, recipient vessels, and clinical contexts. Two anastomoses were converted to conventional suture technique intraoperatively, and one late postoperative venous thrombosis occurred after fistulization and vessel exposure. CONCLUSIONS: We conclude that the MACD studied here is best suited for the end-to-end anastomosis of soft, pliable, minimally discrepant vessels. Previous radiation therapy does not appear to be a contraindication to its use. Interpositional vein grafts may also be well suited to anastomosis with the device. When carefully and selectively employed by experienced microvascular surgeons, this MACD can be a safe, fast, and reliable adjunct in head and neck free-tissue transfer reconstructions, greatly facilitating the efficiency and ease of application of these techniques.

Adult↗

PubMed1995

Injected liquid silicone, chronic mastitis, and undetected breast cancer.

Although the use of injected liquid silicone for breast augmentation has all but ceased since its widespread use in the 1960s, patients with injected silicone are still seen with a multitude of symptoms. Silicone mastitis is a well-documented phenomenon; however, there has been a paucity of information regarding cancer detection in this group of patients. We report 2 patients who presented with chronic mastitis but on further workup were found to have breast cancer. In both patients, early cancer detection was adversely affected by the presence of free liquid silicone. In view of this and other similar case reports, we advise that simple mastectomy be recommended to those patients with breasts inspissated with liquid silicone who not only have suspicious masses but present with recurrent mastitis or a family history of breast cancer.

Adenocarcinoma↗

PubMed1995

Clinical significance of intracapsular fluid in patients' breast implants.

Clinical reports on the incidence and clinical significance of intracapsular fluid are lacking in the literature. It remains unknown whether the presence of intracapsular fluid has any relation to implant infection or colonization. The purpose of this study was to determine the frequency and type of intracapsular fluid, specifically, whether intracapsular fluid causes implant infection, implant rupture, or bacterial colonization. A total of 139 implants from 72 symptomatic patients were entered into the prospective clinical study. Our study demonstrated the presence of intracapsular fluid in 21 of 139 (15%) implants. Positive microbial cultures were identified in 39% of the implants in the positive intracapsular fluid group, compared to 43% in the negative fluid group. There was no statistically significant difference between these groups. Also, no adverse clinical relationship was demonstrated between local symptoms and presence of intracapsular fluid. There was, however, a positive trend toward the presence of fluid when implant shell types were nonsmooth (polyurethane and textured silicone implants). Further studies are indicated to elucidate the fluid production mechanism and possible secretory activity of prosthetic capsules interfacing the textured breast implant surface.

Adult↗

PubMed1995

Evaluation of autogenous tissue breast reconstruction using MRI.

Recent controversy encountered with silicone breast implants has increased the use of autogenous tissue for breast reconstruction following mastectomy. Surveillance of patients who have undergone autogenous tissue reconstruction is important in the evaluation of recurrent or new cancer. Magnetic resonance imaging (MRI) has proven to be a useful technique in the delineation of soft tissues and provides excellent resolution. Recently, MRI has been reported to be a valuable diagnostic imaging modality for the evaluation of augmented breast implant patients with regard to implant rupture detection, silicone granuloma identification, and silicone gel migration delineation. In this study, various autologous tissue donor sites currently available for breast reconstruction were imaged by MRI. The following donor flaps were included: fleur-de-lis, TRAM, gluteal, and tensor fasciae latae. A total of 10 clinical cases were investigated. The anatomic basis of each flap type is illustrated, and various tissue components of flap tissue (skin, fat, and muscle) are demonstrated on MRI scan. Anatomic knowledge of autogenous tissue types and MRI appearance of the flap-breast-chest-wall interface are critical in the surveillance and follow-up of breast cancer patients.

Breast↗

PubMed1994

In vivo anatomic study of cutaneous perforators in free flaps using magnetic resonance imaging.

Adequate knowledge of perforator location preoperatively will enable the surgeon to achieve optimal flap design and flap survival. Most previous attempts have relied on the use of Doppler ultrasound and earlier anatomic knowledge. With ultrasound, there may at times be signals from overlapping blood vessels. Magnetic resonance imaging (MRI) is sensitive to flowing blood and, on an MRI scan, dark-flow void characterization is used to identify perforators. This study was undertaken to evaluate the anatomic location and the number of perforators in the flap zone, based on inherent blood flow, and to determine information about the dominant perforators for free-flap design, using MRI. The CSMEMP technique allowed the characterization of flow void signals, which appeared in the image as dark spots. This technique also enabled differentiation of the surrounding tissue, with a high degree of accuracy. The relationship of the perforators aided in an "ideal" flap design. No necrosis was noted in any of these cases. It appears from this study that MRI can be a useful imaging modality, to assess the location and number of perforators in musculocutaneous flaps.

Adult↗

PubMed1994

Analysis of suturing techniques in the microvascular anastomosis of vessels of unequal diameter.

A rat model has been devised to study the determinants of microvascular anastomotic patency in the setting of diameter discrepancy. Isogeneic interposition grafts of rat inferior vena cava were used to repair a femoral artery defect (diameter ratio 4.5:1). Three methods for compensating for diameter discrepancy were studied. The anastomoses were explored on postoperative days 3, 7, and 14. By 2 weeks, tapered grafts were shown to result in higher patency rates (p < 0.05) compared with nontapered and spatulated grafts. Hemodynamic, histological, and scanning electron microscopic analysis suggested that turbulence caused by large velocity gradients predisposes to thrombosis. This animal model was shown to be sensitive to experimental hemodynamic alterations and may be useful in elucidating the effect of technical or pharmacological manipulations on patency in the setting of vessel diameter discrepancy.

Anastomosis, Surgical↗

PubMed1994

Regional silicone-gel migration in patients with ruptured implants.

The current literature is reviewed, and four clinical cases of silicone-gel migration are reported. All 4 patients reported here had histories of closed capsulotomy, and all were symptomatic. Preoperative magnetic resonance imaging demonstrated the anatomical locations of silicone-gel migration into the chest wall muscles, axillae, and upper extremity. Intraoperative and pathological findings correlated with the presence of silicone-gel migration and granulomas in various anatomical regions. With the recent advances in diagnostic breast imaging of silicone-implant patients, intracapsular rupture can be identified. Implant removal may be indicated for intracapsular ruptures to prevent silicone-gel migration into parenchyma, chest wall muscles, axillae, and the upper extremity.

Adult↗

PubMed1994

Silicone implant rupture diagnosis using computed tomography: a case report and experience with 22 surgically removed implants.

Silicone elastomer shell rupture is a complication of silicone implants. To date, the rate of implant rupture has not been well documented. Magnetic resonance imaging and sonography are noninvasive breast implant imaging modalities that have been shown to be useful in evaluating the integrity of implants. We present a case of rupture detection using a follow-up computed tomographic (CT) scan of a breast cancer patient, which prompted us to use CT scans to evaluate explants of patients undergoing implant removal surgery. The purpose of the investigation was to evaluate the effectiveness of CT scan in detecting rupture. CT scan was performed on 22 explants with intact capsules, for which 17 ruptures were confirmed: 16 true-positive ruptures, 5 true-negative ruptures, O false-positive ruptures, and 1 false-negative rupture were identified. CT scan was shown to be highly sensitive and specific in rupture detection, comparable to magnetic resonance imaging. Although CT scans are consistently reliable, patients are exposed to ionizing radiation; therefore, it is not recommended for patients with augmentation mammoplasty. This study characterizes the appearance of implant rupture on CT scan, which may be useful in evaluating breast cancer patients reconstructed with silicone implants.

Breast Implants↗

PubMed1994

Clinical experience with the 3M microvascular coupling anastomotic device in 100 free-tissue transfers.

The microvascular surgical anastomosis remains one of the most technically sensitive aspects of free-tissue transfers. To facilitate these often time-consuming, difficult anastomoses, various anastomotic coupling systems have been introduced. The 3M microvascular anastomotic coupling device, a polyethylene ring-pin device, was found to be highly successful in numerous animal studies. It has been available for use in human subjects for the last 4 years, but clinical experience remains sparse. Our clinical experience with the 3M coupler is reported in 100 free-tissue transfers. The average anastomotic time was 4 minutes. Mean follow-up was 8.6 months, and flap survival was 100 percent. The overall success rate for 3M (MACD) coupler use in microvascular anastomoses is 98.4 percent (121 of 123). Nine abandoned anastomoses were converted to sutured anastomoses intraoperatively. The over-all failure rate for 3M coupler anastomoses is 1.6 percent (2 of 123). We conclude that the 3M device is best suited for minimally discrepant, soft, pliable venous microvascular anastomoses and is unsuitable for end-to-side anastomoses in clinical situations. When carefully and selectively employed by a trained microvascular surgeon, the 3M coupler can be a safe, fast, and reliable adjunct for free-tissue transfers.

Adult↗

PubMed1994

Comparative silicone breast implant evaluation using mammography, sonography, and magnetic resonance imaging: experience with 59 implants.

With the current controversy regarding the safety of silicone implants, the detection and evaluation of implant rupture are causing concern for both plastic surgeons and patients. Our study obtained comparative value analysis of mammography, sonography, and magnetic resonance imaging (MRI) in the detection of silicone implant rupture. Twenty-nine symptomatic patients (total of 59 silicone implants) were entered into the study. Intraoperative findings revealed 21 ruptured implants (36 percent). During physical examination, a positive "squeeze test" was highly suggestive of implant rupture. Mammograms were obtained of 51 implants (sensitivity 11 percent, specificity 89 percent). Sonography was performed on 57 implants (sensitivity 70 percent, specificity 92 percent). MRI was performed on 55 implants (sensitivity 81 percent, specificity 92 percent). Sonographically, implant rupture is demonstrated by the "stepladder sign." Double-lumen implants may appear as false-positive results for rupture on sonography. On MRI, the "linguine sign" represents disrupted fragments of a ruptured implant. The most reliable imaging modality for implant rupture detection is MRI, followed by sonogram. Mammogram is the least reliable. Our study supports the clinical indication and diagnostic value of sonogram and MRI in the evaluation of symptomatic breast implant patients.

Breast Diseases↗

PubMed1994

Silicone breast implant ruptures in an animal model: comparison of mammography, MR imaging, US, and CT.

PURPOSE: To determine the most accurate imaging modality for detection of silicone implant ruptures. MATERIALS AND METHODS: Forty single-lumen silicone implants were surgically placed in 20 rabbits. Each rabbit received one intact and one ruptured implant and was examined with mammography, magnetic resonance (MR) imaging, ultrasound (US), and computed tomography (CT). Five radiologists reviewed all images in a random fashion and graded each for rupture. The radiologist who performed US also graded her impression during examination with US. Receiver operating characteristic (ROC) analysis was performed. RESULTS: MR imaging and CT were the most accurate modalities in detection of implant ruptures, with areas under the ROC curves (Az) of .95 and .91. Mammography and US were statistically significantly inferior, with Az of .77 for each (P < .05). CONCLUSION: MR imaging and CT are statistically more accurate than US and mammography for detection of intracapsular silicone implant ruptures when only the images are reviewed.

Animals↗

PubMed1994

Silicone breast implant rupture: comparison between three-point Dixon and fast spin-echo MR imaging.

OBJECTIVE: This study was designed to compare the three-point Dixon technique with our present MR protocol incorporating T2-weighted fast spin echo and fast spin echo with water suppression to detect ruptured silicone breast implants. SUBJECTS AND METHODS: Eighty-two symptomatic women with silicone breast implants were examined with both the three-point Dixon technique and fast spin-echo MR sequences. Of these patients, 41 had surgery to remove their implants. Four radiologists reviewed the images from only those patients who had surgery and graded each for rupture by using a scale of 1-5. Receiver-operating-characteristic analysis was performed. RESULTS: Of 81 implants removed, 18 were ruptured. Silicone implant ruptures were identified more frequently on the fast spin-echo sequence than on the three-point Dixon sequence, with areas under the ROC curves of .95 and .84, respectively. Although the difference was not statistically significant, the sensitivity for detecting silicone implant rupture was 89% for the fast spin-echo sequence and 61% for the three-point Dixon sequence. The specificity was 97% for both sequences. CONCLUSION: Silicone implant ruptures were detected more frequently with fast spin-echo MR sequences than with the three-point Dixon technique, although the difference was not significant. The greater spatial resolution used for the fast spin-echo sequence partially accounts for the difference in detection of implant ruptures in this study.

Breast↗