Figure 1. Histology of Mönckeberg medial calcific sclerosis. Hematoxylin and eosin–stained section of a muscular artery (original magnification ×200) exhibits calcification (arrows) centered on the internal elastic lamina and extending into the media. No luminal encroachment is seen.
Figure 2. Image of lower-extremity calcifications. Plain film radiograph demonstrating severe calcification affecting the posterior tibial artery after harvest of a fibula free flap.
Figure 3. Image of upper-extremity calcifications. Plain film radiograph demonstrating severe calcification affecting the radial artery.
Figure 4. Magnetic resonance angiogram demonstrating widely patent posterior tibial and peroneal arteries despite the known presence of severe vascular calcification. AT indicates anterior tibial artery; P, peroneal artery; and PT, posterior tibial artery.
Lee MK, Blackwell KE, Kim B, Nabili V. Feasibility of Microvascular Head and Neck Reconstruction in the Setting of Calcified Arteriosclerosis of the Vascular Pedicle. JAMA Facial Plast Surg. 2013;15(2):135-140. doi:10.1001/2013.jamafacial.208
Author Affiliations: Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA (University of California, Los Angeles).
Objective To report outcomes in free flap reconstructive surgery in the setting of calcified arteriosclerosis affecting the flap pedicle.
Design Retrospective review, including a detailed analysis of medical records, histopathologic findings, and a comprehensive review of the literature.
Methods A total of 1329 consecutive microvascular free tissue transfers were performed by 2 reconstructive surgeons at a university-affiliated tertiary care medical center from January 1, 1996, through December 31, 2011. Clinical notes, operative notes, and pathology reports were systematically reviewed to identify 44 patients (3%) with calcified arteriosclerosis involving the flap vascular pedicle. A comprehensive medical record review was performed for the included patients, detailing patient-related characteristics, flap survival, and incidence of perioperative complications.
Results A history of arteriosclerosis was identified preoperatively in 18 patients (41%). Eight patients (18%) were specifically recognized clinically and histologically to have a variant of arteriosclerosis known as Mönckeberg medial calcific sclerosis. In total, fibula osteocutaneous free flap was performed in 30 patients, radial forearm in 8 patients, rectus abdominus in 3 patients, latissimus dorsi in 2 patients, and parascapular in 1 patient. Perioperative complications occurred in 17 patients (39%), with the most common being pulmonary (14%) and cardiac (9%). Patient follow-up ranged from 3 to 137 months, with a mean postoperative follow-up of 21 months. The mean length of hospital stay was 12 days. There was a 0% incidence of total flap failure and a 7% incidence of partial flap necrosis.
Conclusion Although technically challenging, successful microvascular free flap reconstruction can be achieved despite the presence of vascular calcifications affecting the flap vascular pedicle.
During the past several decades, microvascular free tissue transfer has risen to the forefront as the preferred method of reconstruction for complex defects of the head and neck.1 With an increased understanding of flap physiology and refinement of surgical technique, microvascular free tissue transfer has demonstrated extraordinary consistency as a reconstructive modality, with success rates ranging from 96% to 99%.1- 6 As such, the reliability and versatility of the free flap reconstruction is unparalleled in head and neck surgery.
Despite the widely acknowledged reliability of microvascular reconstruction, several risk factors have been commonly cited as increasing the risk of flap failure, including obesity, age, smoking, previous irradiation, diabetes, and systemic vascular disease.7 In particular, the presence of arteriosclerosis affecting the donor or recipient vessels has been identified as increasing the complication rate and the technical difficulty of free flap reconstruction.8,9 There are several mechanisms on which this assertion is founded. In the setting of arteriosclerosis, there is a purported increased risk of separation of the tunica intima from the tunica media with the passing of transmural sutures during the microvascular anastomosis. This may subsequently contribute to an elevated risk of thrombosis and anastamotic failure.8 In addition, the arteries used for the microvascular anastomosis in atherosclerotic patients may lose their elasticity secondary to vascular calcifications, rendering the arrangement of ideal pedicle geometry particularly challenging.
Outcomes of microvascular free tissue transfer for head and neck reconstruction when flap vascular pedicles are affected by calcified arteriosclerosis have not been well described. The goal of the current study was to report outcomes of microvascular head and neck reconstruction performed in patients with peripheral vascular disease causing the flap vascular pedicle to be affected by calcified atherosclerosis.
Approval from the institutional review board of UCLA was obtained before implementation of this study. From January 1, 1996, through December 31, 2011, a total of 1329 consecutive microvascular free flaps were performed by 2 head and neck reconstructive surgeons (K.E.B. and V.N.) at a university-affiliated tertiary care medical center. For these cases, a comprehensive medical record review was then implemented.
Operative notes and pathology reports were reviewed in detail to identify those patients in whom donor and/or recipient vessels were affected by calcified arteriosclerosis. Specifically, operative reports were queried for the words atherosclerosis, arteriosclerosis, calcification, or calcified. In those cases identified, surgical pathology reports were then reviewed to histologically confirm the presence of calcified arteriosclerosis. A clinical diagnosis of calcified arteriosclerosis was defined as when the degree of atherosclerosis and calcification resulted in loss of vessel elasticity and made it difficult to obtain adequate pedicle geometry or when the degree of calcification made it difficult for sutures to be passed through the vessel walls during the microvascular anastomosis. This diagnosis was then confirmed through histopathologic analysis, obtained from vascular tissue trimmed from the ends of the donor and recipient vessels and then sent to pathology at the time of surgery.
A comprehensive medical record review was performed for the included patients, detailing patient-specific data and free flap survival. Patient-specific characteristics included age, sex, American Society of Anesthesiology status, history of preoperative chemotherapy or radiation therapy, and medical comorbidities such as known coronary artery disease, peripheral vascular disease, renal insufficiency, and smoking history. Inpatient and outpatient clinical notes were reviewed to identify the incidence of postoperative complications and flap survival. The incidence of partial and total flap necrosis was recorded, in addition to the rate of fistula formation and donor site complications. Perioperative complications were defined as complications occurring within 90 days after surgery and were categorized by organ systems (cardiac, pulmonary, infectious, gastrointestinal, hematologic, renal, genitourinary, neurologic, and endocrine).
Of the 1329 total free flaps, 49 patients were identified as having calcified arteriosclerosis affecting the donor vessels of the vascular pedicle. From this group, 5 patients were excluded because of lack of sufficient outpatient follow-up (defined as <90 days), rendering a total of 44 patients (13 women and 31 men) for inclusion in the current study (Table 1). The mean (range) patient age was 70 (49-88) years and follow-up was 21 (3-137) months. A preoperative history of coronary artery disease or peripheral vascular disease was identified in 14 (32%) and 10 (23%) patients, respectively. Four patients (9%) reported renal insufficiency, with 1 patient requiring regular hemodialysis and another being the recipient of a cadaveric renal transplantation. Twenty-seven patients (61%) reported a history of smoking. Twenty-four patients (55%) had undergone radiation therapy to the neck before surgery.
Eight of the 44 patients (18%) were found to have a specific histologic variant of atherosclerosis known as Mönckeberg medial calcific sclerosis (Figure 1), with 4 of these patients having a preoperative diagnosis of vascular disease noted before undergoing surgery. All 8 of these patients were noted to have particularly severe vascular calcification at the time of the microvascular anastomosis. A postoperative plain film radiograph of the lower extremity is shown in Figure 2 and of the upper extremity in another patient in Figure 3. Both of these patients experienced Mönckeberg medial calcific sclerosis, with plain film imaging demonstrating the extensive nature of vascular calcifications characteristic of this disease process. Additional patient-specific data are summarized in Table 1. The fibula osteocutaneous free flap (n = 30) was the most common reconstructive flap performed, followed by the radial forearm free flap (n = 8). Flap donor sites are summarized in Table 2.
There was a 0% incidence of total flap necrosis and a 7% (n = 3) incidence of partial flap necrosis, all involving a portion of the skin paddle from fibula free flaps. Of these, 2 patients were managed with local wound care, and 1 patient required revision surgery.
Overall, perioperative complications occurred in 39% of patients. Complications were categorized by organ system, as delineated in Table 3. Pulmonary complications, such as development of pneumonia, were most common (14%). This was followed by cardiac complications (9%), which included development of postoperative atrial fibrillation, perioperative myocardial infarction, and supraventricular tachycardia.
Fistula formation occurred in 5% of patients, all of which resolved by conservative wound care. Donor site complications occurred in 3 patients (7%), all of whom had undergone fibula osteocutaneous free flaps. This included 1 case of a localized cellulitis of the donor site, 1 case in which the split-thickness skin graft to the donor site failed to take, and 1 case of foot drop following flap harvest. The mean (range) hospital stay was 12.3 (6-38) days (median, 9 days), with a statistically significant increase (P = .01) in length of hospital stay for patients who developed perioperative complications (mean, 15.8 days, and median, 12 days; σ = 8.7) vs those who did not (10.1 and 8 days; σ = 5.4).
Microvascular free tissue transfer has gained wide acceptance as the preferred method of reconstruction for complex defects of the head and neck. Although the method was initially met with some hesitation owing to concerns regarding their perceived dependability, subsequent studies1- 6 have confirmed the unparalleled reliability and versatility of free flaps as a reconstructive technique. Reconstruction of defects following oncologic resection of head and neck cancer is one of the most common indications for free flap surgery. This disease process most commonly affects patients between the fifth and seventh decades of life,2 a finding reflected in the mean age of patients included in the current study. Given their advanced age, candidates for free flap surgery often present with numerous comorbid medical conditions, such as systemic atherosclerosis as manifested through coronary artery or peripheral vascular disease. The presence of atherosclerosis has often been cited as a significant risk factor for flap failure and perioperative complications.7- 10
A number of mechanisms have been identified as contributing to the increased risk of flap failure in atherosclerotic patients. The tunica intima of atherosclerotic vessels is vulnerable to separation from the tunica media, exposing the thrombogenic subepithelium and elevating the risk of anastamotic failure secondary to vascular thrombosis. This risk is thought to be elevated in patients with arteriosclerosis.8,11 In addition, the severity of atherosclerosis affecting the donor vessels may entirely preclude the use of certain free flaps. This is a well-known consideration during the preoperative evaluation of lower-extremity donor sites such as the fibula osteocutaneous free flap, and preoperative vascular imaging studies are often performed in these patients to rule out the possibility of occluded or stenotic vessels and to evaluate for atherosclerotic vascular malformation.12 Furthermore, vessels affected by atherosclerotic changes often develop associated vascular calcifications leading to a loss of vessel elasticity and compliance.13 In these patients, the loss of elasticity in the anastamotic vessels may render the arrangement of ideal pedicle geometry particularly challenging. This may result in significant difficulty manipulating these vessels into an ideal position that will minimize undue shear force and prevent kinking of the anastomoses.
For all of these reasons, atherosclerosis and its associated vascular calcification have been commonly implicated as significant risk factors for flap failure. Although this assertion seems ubiquitous in the free flap literature, it has not been well substantiated by larger studies evaluating the viability of free flaps specifically in the setting of severe arteriosclerosis. The most comprehensive study to date was described by Serletti et al,10 who reported outcomes in 30 patients undergoing microvascular free tissue transfer for lower limb salvage related to peripheral vascular compromise. The authors described a 10% early flap failure rate in these patients known to have vascular disease, supporting the commonly stated contention that systemic arteriosclerosis does in fact decrease the reliability of microvascular free tissue transfer. This may in part be explained by the extensive involvement of the recipient vessels in the report by Serletti et al,10 which would lead to a state of low flap in-flow. By contrast, only donor vessels were affected by calcified arteriosclerosis in the current study.
Given the high reliability of free flaps for the head and neck,1- 6 this raises the question as to whether patients with peripheral vascular disease are a subset with potentially diminished free flap reliability. To the contrary of many earlier publications, in the current study, the incidence and pattern of postoperative complications and the risk of partial or total flap necrosis in patients with calcified atherosclerosis of the flap vascular pedicle was found to be similar to that which our group previously reported in 400 consecutive patients who underwent microvascular flap reconstruction of the head and neck.1 Our results lend support to the notion that free flap surgery is a feasible and reliable technique for head and neck reconstruction, despite the presence of systemic vascular disease affecting the donor flap vessels that makes flap revascularization more challenging.
The development of vascular calcification is a well-known element in the pathogenesis of atherosclerosis and has been associated with an increased risk of atheroma plaque instability and resultant thrombus formation.14 For those with a known history of atherosclerosis, considerations and appropriate adjustments are made to the treatment plan preoperatively and intraoperatively, as has been described by Chen et al7 and Miyamoto et al.8 These considerations may include selection of a flap donor site less commonly affected by atherosclerotic disease, alterations in the selection of recipient vessels, and adjustment of the surgical technique to minimize potential disruption of atherosclerotic plaques during the preparation and execution of the microvascular anastomosis.
In this series, fibula flaps were disproportionately affected by calcified atherosclerosis. Fibula flaps consisted of 30 of 44 cases (68%) when compared with 578 of 1329 free flaps (43%) performed during the entire study period. Magnetic resonance angiography, which is often used for preoperative donor site evaluation in patients who undergo fibula flap reconstruction, has poor sensitivity to the detection of vascular calcifications independent of luminal stenosis.15 This is clearly exemplified in Figure 4, which illustrates magnetic resonance angiography performed preoperatively in a patient with Mönckeberg sclerosis who underwent a fibula osteocutaneous free flap. The peroneal artery demonstrates wide patency despite intraoperative findings of severe calcified arteriosclerosis affecting the donor vessels. Plain films from this same patient are illustrated in Figure 2, revealing the extensive nature of vascular calcification in patients affected by Mönckeberg sclerosis, despite the lack of luminal stenosis.
Given the low sensitivity of magnetic resonance angiography for detecting this type of disease pathology, adjunctive imaging studies may be considered for patients planned for fibula free flap surgery. Plan film radiography and color flow Doppler are imaging modalities that can identify vascular calcifications with a higher degree of sensitivity than magnetic resonance angiography. These radiographic studies may be considered as alternative or adjunctive imaging studies in patients who are being evaluated for fibula flap transfer when there is a suspicion for increased risk of vascular calcifications. Although we have shown that free flap reconstruction is highly successful in patients with vascular calcifications affecting the vascular pedicle, in some cases it may be possible to select an alternative flap donor site that is not affected by vascular calcifications.
Interestingly, only 32% and 23% of patients included in the current study were identified as having a preoperative history of coronary artery disease or peripheral vascular disease, respectively. Ideally, it would be advantageous to identify patients at high risk for vascular calcification and consider them for flap donor sites less affected by vascular calcification. However, given that most affected patients had no identifiable history of atherosclerosis preoperatively, these patients often cannot be identified on the basis of medical history alone. In addition, only 8 of the 30 patients (27%) who had undergone fibula free flaps (and by protocol were evaluated for donor vessel patency by magnetic resonance, computed tomography, or conventional angiography) had radiographic findings indicative of atherosclerosis of the peroneal artery. As summarized in Table 4, all imaging modalities demonstrated a low sensitivity in detecting atherosclerotic disease, although the number of cases studied is too small to draw definitive conclusions about the utility of these studies in detecting vascular calcifications.
Given the results of this preoperative imaging, most of these patients were determined to be appropriate fibula free flap candidates because of the lack of demonstrable atherosclerosis of the donor vessels. In addition, 18% of patients with severe vascular calcification were affected by Mönckeberg medial calcific sclerosis, a disease process that involves the calcification of the medial layer of muscular arteries, most typically affecting the vasculature of the extremities.16 More important, patients with Mönckeberg sclerosis may be completely asymptomatic on the basis of findings from angiographic studies that show no abnormalities because this disease process often occurs independently of atherosclerosis and in the absence of any vessel luminal stenosis.17 Mönckeberg sclerosis can affect donor vessels that are typically spared by conventional atherosclerosis and accordingly are not evaluated by routine preoperative radiographic imaging. In addition, clinical examination by palpation of the peripheral pulses can often show no abnormalities in patients with Mönckeberg sclerosis.
Given these confounding factors, surgeons will on occasion encounter unanticipated cases of calcified atherosclerosis of the vascular pedicle despite a comprehensive preoperative evaluation. In these cases, modification in anastomotic techniques and careful planning of vessel geometry can help to assure a successful outcome. When considering flap ischemia time, additional time should be devoted to the creation of microvascular anastomoses in patients with calcified atherosclerosis of the vascular pedicle. We have found that use of microvascular cutting needles (Sharpoint Microsutures; Angiotech), as opposed to taper vascular needles, is helpful to penetrate densely calcified arteries, but even a cutting needle will not penetrate vessel walls in areas of severe calcification. In such cases, inspection and palpation of the vascular pedicle helps to identify areas for anastomosis that are relatively spared by vascular calcification. Areas of relative sparing are often located at the site of large side branches of the vascular pedicle. During creation of the anastomosis, calcified plaques can sometimes be avoided by placement of obliquely oriented sutures. Care must be taken to avoid overtightening of knots when tying sutures because the sharp edge of a calcified plaque can cut the suture. We also use minimal trimming of the adventitia in cases of dense vascular calcification. This allows for placement of adventitial sutures to control leakage from the anastomosis when vessel calcification allows for placement of fewer than the desirable number of transmural sutures or requires placement of obliquely oriented transmural sutures. Finally, great care must be taken when planning vessel geometry to prevent kinking of the rigid flap vascular pedicle.
In conclusion, calcified arteriosclerosis of the vascular pedicle is occasionally encountered in patients who undergo microvascular free tissue transfer for head and neck reconstruction. Fibula flaps are disproportionately affected compared with other flap donor sites. Although historically free flap surgery has been thought to be less reliable in the setting of arteriosclerosis and vascular calcification, the current study demonstrates the reliability of microvascular free tissue transfer for head and neck reconstruction despite this risk factor. Additional imaging modalities, such as plain film radiography and color flow Doppler, may be helpful in identifying patients with calcified arteriosclerosis. Ultimately, careful intraoperative planning and modification of surgical techniques helps to assure a successful outcome when vascular calcifications are encountered.
Correspondence: Matthew K. Lee, MD, Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 62-132, Los Angeles, CA 90095 (firstname.lastname@example.org).
Accepted for Publication: August 15, 2012.
Published Online: December 31, 2012. doi:10.1001/2013.jamafacial.208
Author Contributions:Study concept and design: Lee, Blackwell, and Nabili. Acquisition of data: Lee, Blackwell, Kim, and Nabili. Analysis and interpretation of data: Lee, Blackwell, Kim, and Nabili. Drafting of the manuscript: Lee, Kim, and Nabili. Critical revision of the manuscript for important intellectual content: Lee, Blackwell, and Nabili. Statistical analysis: Lee, Kim, and Nabili. Study supervision: Lee, Blackwell, and Nabili.
Conflict of Interest Disclosures: None reported.
Previous Presentation: This study was presented at the American Academy of Facial Plastic and Reconstructive Surgery Spring Scientific Meeting in conjunction with the Combined Otolaryngological Spring Meetings; April 19, 2012; San Diego, California.