Anterior single rod instrumentation for thoracolumbar adolescent idiopathic scoliosis with and without the use of structural interbody support

STUDY DESIGN

A radiographic and clinical outcomes analysis of 41 patients treated for thoracolumbar adolescent idiopathic scoliosis utilizing a single anterior rigid rod construct.

OBJECTIVES

To evaluate the necessity of structural interbody support to improve primary curve correction and preserve or augment lordosis when used in conjunction with a single anterior rigid rod construct, to identify parameters that predict horizontalization of the lowest instrumented vertebra, adjacent disc angulation, and distal uninstrumented vertebrae, and to assess patient satisfaction following surgery.

BACKGROUND DATA

Instrumentation-induced kyphosis has been a concern with nonrigid anterior systems used in the past for the treatment of scoliosis. Interbody structural support has been recommended to maintain appropriate sagittal profile when anterior systems are utilized. It has also been suggested that the use of structural interbody support creates a fulcrum to increase curve correction when compression is applied to the convexity of the deformity. However, the necessity of interbody structural support when used in conjunction with a rigid anterior system has not been previously evaluated in patients with adolescent idiopathic scoliosis.

MATERIALS AND METHODS

Forty-one patients mean age 15.9 years (range 12.1-18.6 years) with thoracolumbar adolescent idiopathic scoliosis underwent anterior spinal fusion using a single 6.0 to 6.5 mm solid rod construct between June 1995 and August 1999 performed by the senior author (T.G.L.). Four additional patients with thoracolumbar curves with similar anterior instrumentation over the same time period were lost to follow-up or had incomplete records and were not included in the study. Structural interbody support was used in 21 patients and packed morselized autograft alone was used in 20 patients. The patients in the group with packed morselized bone alone generally underwent surgery earlier in the series before the author began using structural interbody support on a regular basis. Each patient had a minimum follow-up of 3 years. Preoperative, initial, and most recent (>3 years) follow-up radiographs were reviewed to determine in each group Cobb angle measurements, flexibility of primary, secondary, and fractional curves, apical and end vertebral translation, lowest instrumented vertebral and caudal disc angulation, global coronal and sagittal balance, and sagittal Cobb measurements in both instrumented levels as well as lumbar lordosis (T12-S1). In addition, the SRS outcomes instrument was completed by 38 of 41 patients.

RESULTS

The mean preoperative primary curve in patients with structural support was 47 degrees (Group II) and 45 degrees in patients without structural support (Group I). Mean curve correction was to 13 degrees in Groups I and II. One patient in Group II became slightly more unbalanced at final follow-up; otherwise all were improved after surgery. Sagittal measurements over instrumented segments as well as total lumbar lordosis (T12-S1) was maintained between preoperative and final postoperative values in both groups. Similarly, in both groups, when horizontalization of the distal end instrumented vertebra was achieved on the preoperative reverse side-bending radiograph, more normal relationships were achieved between instrumented and distal noninstrumented segments (adjacent disc angulation and fractional lumbar curve) at final follow-up (P <or= 0.01). Patients in both groups were equally pleased with their clinical outcomes based on the SRS outcomes instrument.

CONCLUSIONS

The use of interbody structural support does not appear to be necessary to maintain an appropriate sagittal profile or to maximize coronal curve correction when a rigid rod construct with packed morselized bone is used for the treatment of thoracolumbar adolescent idiopathic scoliosis. Parameters predicting horizontalization of the lower instrumented vertebra and uninstrumented segments below the construct were identified, which, if achieved, should predict an optimal long-term outcome. Clinical outcomes were very good in both groups.

Analysis of patient and parent assessment of deformity in idiopathic scoliosis using the Walter Reed Visual Assessment Scale

OBJECTIVES

This study evaluates the Walter Reed Visual Assessment Scale (WRVAS) compared with clinical parameters and written descriptions of the deformity from idiopathic scoliosis patients and their parents.

SUMMARY OF BACKGROUND DATA

The WRVAS demonstrates seven visible aspects of spinal deformity in an analogue scale. Higher scores reflect worsening deformity.

MATERIALS AND METHODS

The WRVAS was administered to 182 idiopathic scoliosis patients at four centers in conjunction with open-ended questions about patients' and their parents' perceptions of their spinal deformity. The open-ended responses were categorized as either "deformity noted" or "no deformity noted."

RESULTS

WRVAS scores strongly correlate with curve magnitude (P = 0.01) and clearly differentiates curves of 30 degrees or more from lesser curves. Among treatment groups, patients with surgery recommended had significantly higher scores than that of other patients. The instrument differentiated those noting no deformity from those noting a deformity. The correlation between patients' and parents' scores was high (Spearman's rho = 0.8). When a deformity was noted, parents gave higher scores than did their children for rib prominence, shoulder level, scapular rotation, and the total score, but not for the other dimensions.

CONCLUSIONS

Increasing scores of the WRVAS are strongly correlated with curve magnitude lending construct validity to this type of assessment tool. Patients with "surgery recommended" report more visible deformity on the scale than observed, braced, and postoperative patients, supporting the hypothesis that surgery improves the perceived appearance. Parents perceive more deformity of the ribs and shoulders more than did the patients, but other aspects of the deformity are identified equally. WRVAS scores correlate significantly with curve magnitude and treatment. Parents and patients have similar scores, but with parents perceiving more deformity of the ribs and shoulders than patients.

Low-grade isthmic/lytic spondylolisthesis in adults

Three basic classification schemes have been developed to categorize spondylolisthesis, the slippage or forward displacement of one vertebra over another. Two rely on radiographic appearance, and the third stresses the developmental aspect of the pathology. The pathology is relatively rare in individuals younger than 18 years, appears to be influenced by race, and is found more frequently in males than females and in patients with symptomatic low back pain. Lytic spondylolisthesis occurs more frequently at certain spinal levels, and certain sports activities have been implicated in its development. The etiology remains unclear, but hereditary factors are unlikely with no evidence of the lytic defect in newborns. Recent research indicates that the architecture of the pelvis may be an important parameter. Some have postulated that the underlying pathomechanical event is a fracture, either acute or secondary to fatigue. Once the pars defect has been created, anatomic and biomechanical forces conspire to prevent healing of the fracture and create a spondylolisthesis. Although mechanical considerations are likely most significant, genetic considerations have also been discussed. All the imaging modalities play useful roles in defining the pathoanatomy, including diskography. Patients typically report symptoms as back pain and/or neurologic symptoms; however, these symptoms can have other causes even though a spondylolisthesis is present. A thorough history and physical examination, along with the radiographic investigations, are essential to determining proper treatment. Nonsurgical options are activity modification, bracing, physical therapy, and intervention in the form of medications or injections. Use of muscle relaxers and narcotics may be appropriate for managing initial acute pain. Surgical options are direct repair of the pars defect, decompression, fusion, or a combination of these procedures. The various techniques of pars repair are recommended only for patients younger than 30 years. Although decompression alone may be suitable in some situations, decompression with fusion is more standard, certainly when instability and low back pain exist.

Histology of the craniocervical junction in chronic rheumatoid arthritis: a clinicopathologic analysis of 33 operative cases

STUDY DESIGN

A histologic review of surgical specimens with clinical and radiographic correlations.

OBJECTIVE

To analyze the histopathology at the craniocervical junction in chronic rheumatoid arthritis (RA).

SUMMARY OF BACKGROUND DATA

It has been assumed that the tissue identified on radiography at the craniocervical junction causing anterior spinal cord compression in patients with chronic RA is hypertrophic rheumatoid synovium. To date, no study has positively identified the histology of this tissue.

METHODS

Transoral resection of the dens and spinal cord decompression were performed in 33 myelopathic rheumatoid patients with craniocervical instability. The resected specimens were examined histologically.

RESULTS

Two unique histologic patterns were identified. Type I synovium has a recognizable synovial structure but without a hyperplastic synovial layer, significant inflammatory cell population, or lymphocytic infiltration typical of early active rheumatoid synovium. Type II synovium is a bland, fibrous, hypercellular tissue that is hypovascular, with little synovium and few inflammatory cells. Clinically and radiologically the two groups are distinct. Patients with Type II synovium are older ( = 0.008) and present with more advanced neurologic involvement caused by spinal cord compression ( = 0.0001). The mean difference in the spinal cord area between the two groups was 20.6 mm (95% confidence interval, 10.0-31.2 mm; = 0.004).

CONCLUSIONS

The histologic specimens suggest that ligamentous destruction is followed by replacement of the rheumatoid synovium with fibrous tissue, whereas the osseous structures reveal severe destruction secondary to mechanical instability, rather than to an acute inflammatory process. Early, preemptive surgical intervention may prevent the development of spinal cord injury caused by instability.

Chiari I malformation associated with syringomyelia and scoliosis: a twenty-year review of surgical and nonsurgical treatment in a pediatric population

STUDY DESIGN

Retrospective review of patients with Chiari I malformation with or without associated scoliosis.

OBJECTIVES

Determine the effect of decompression of Chiari I malformation with syringomyelia on stabilization or improvement of associated scoliosis.

SUMMARY OF BACKGROUND DATA

Chiari malformations are often associated with spinal deformities, including scoliosis. Studies have suggested a causal relation between syringomyelia and scoliosis.

METHODS

Patients with Chiari I malformation and syringomyelia with or without scoliosis treated over the last 20 years were reviewed. Patients with any other anomalies were excluded. Scoliotic curves were classified by magnitude and curve type. All patients were treated with surgical decompression of the Chiari malformation with or without drainage of the syringomyelia.

RESULTS

Twenty-five patients were identified, ranging in age from 19 months to 16.5 years. Nineteen patients (76%) had associated scoliosis. The majority of the patients with scoliosis (13 of 19) sought treatment for spinal deformity, and only 6 had for pain or neurologic symptoms. Eleven of 19 patients with scoliosis (58%) underwent fusion. Eight of 19 (42%) patients have not undergone fusion: 3 have experienced progress, 1 remains in a stable condition, and 4 have experienced improvement of curvature since undergoing decompression. The mean age of patients who experienced progress after decompression was 14.5 years, compared to 6 years for patients who experienced improvement.

CONCLUSION

Early decompression of Chiari I malformation with syringomyelia and scoliosis resulted in improvement or stabilization of the spinal deformity in 5 cases. Each of these patients underwent decompression before 8 years of age and before the curve was severe. However, this series represents a few patients demonstrating this trend, and further follow-up and investigation are warranted.

Longevity of the Marshall-Marchetti-Krantz procedure

BACKGROUND AND AIMS

The Marshall-Marchetti-Krantz procedure (MMK) is a vesico-urethral suspension, for the correction of urethral hypermobility in women with stress urinary incontinence. This study aims to describe the long-term outcome of the procedure.

MATERIAL AND METHODS

40 women with stress incontinence underwent the MMK. All operations were performed by one surgeon. Analysis of patients' notes yielded the early continence rate and perioperative morbidity. Long-term outcome was measured by means of a postal questionnaire with telephone contact to ensure maximum uptake.

RESULTS

The immediate continence rate was 82%. Continence rates at up to 22 years follow-up (mean 8.5 years) is 61%. All failures occurred within 2 years of the operation.

CONCLUSION

Patients still continent two years after the MMK will maintain continence in the long-term.

Rheumatoid arthritis of the cervical spine: current techniques for management

The incidence of rheumatoid arthritis in the European and North American population is significant. Rheumatoid arthritis can result in serious damage to the cervical spine and the central neuraxis, ranging from mild instability to myelopathy and death. Aggressive conservative care should be established early. The treating physician should not be lulled into a false sense of security by reports suggesting that cervical subluxations are typically asymptomatic [76-78]. Gradual spinal cord compression can result in severe neurologic deficits that may be irreversible despite appropriate surgical intervention when applied too late. [figure: see text] The treatment of rheumatoid disease in the cervical spine is challenging. Many details must be considered when diagnosing and attempting to institute a treatment plan, particularly surgical treatment. The pathomechanics may result in either instability or ankylosis. The superimposed deformities may be either fixed or mobile. The algorithm suggested by the authors can be used to navigate through the numerous details that must be considered to formulate a reasonable surgical plan. Although these patients are [figure: see text] frail, an "aggressive" surgical solution applied in a timely fashion yields better results than an incomplete or inappropriate surgical solution applied too late. When surgical intervention is anticipated, it should be performed before the development of severe myelopathy. Patients who progress to a Ranawat III-B status have a much higher morbidity and mortality rate associated with surgical intervention than do patients who ambulate. Although considered aggressive by some, "prophylactic" stabilization and fusion of a [figure: see text] relatively flexible, moderately deformed spine before the onset of severe neurologic symptoms may be reasonable. This approach ultimately may serve the patient better than "observation" if the patient is slowly drifting into a severe spinal deformity or shows signs of early myelopathy or paraparesis.

Preoperative magnetic resonance imaging screening for a surgical decision regarding the approach for anterior spine fusion at the cervicothoracic junction

STUDY DESIGN

In a study investigating the correlation between a set of designed criteria and judgments of surgical experience, 100 cervical magnetic resonance images from different patients were used.

OBJECTIVES

To demonstrate reliable and reproducible anatomic measurements that can aid spine surgeons in selecting surgical approaches for anterior spine fusion in the cervicothoracic region.

SUMMARY OF BACKGROUND DATA

Surgical approaches to the cervicothoracic junction vary among surgeons. Whereas sternotomy provides maximum exposure, less extensive approaches are preferred to minimize surgical trauma, provided surgical goals are not compromised. No quantitative criteria currently exist to determine before surgery the least invasive surgical approach for sufficiently exposing pertinent anatomy.

METHODS

Thirteen geometric variables designed to be clinically practical and to expose important anatomic relations were used to evaluate 100 sagittal scout cervical magnetic resonance image sequences. An experienced spine surgeon independently rated each image for the most appropriate surgical approach to the C5-T2 region. The ratings were tested for interrater reliability using a second spine surgeon. After testing for interrater and intrarater reliability, the geometric measurements were correlated with the surgeon's selected surgical approaches for each intervertebral segment (P < 0.05).

RESULTS

Instrument manubrial thoracic distances, reflecting standardized heights of intervertebral discs above or below the superior tip of the manubrium, were the most reliable, reproducible, and correlative with the choice of surgical approach. All the measurements but one, the instrument manubrial thoracic distance for T1/T2, demonstrated interrater and intrarater reliability, with an interclass correlation of at least 0.70. The primary surgeon-investigator indicated the anterior approach with sternotomy (n = 3) or the transverse cervical approach (n = 97) for the C7/T1 exposure, and the anterior approach with sternotomy (n = 43) or the transverse cervical approach (n = 57) for the T1/T2 exposure. The interrater questionnaire reliability results indicated statistical agreement between the primary surgeon-investigator and the second cervical spine surgeon at all vertebral segments evaluated. Instrument manubrial thoracic distances showed the strongest significant correlation with the surgical approach, demonstrating a statistical power of 1. For the C7/T1 exposure, the instrument manubrial thoracic distance for C7/T1 was 1.9 +/- 2 cm (95% confidence interval [CI] = 1.41 to 2.22) for the transverse cervical approach, and -3.3 +/- 1.3 cm (95% CI = -4.79 to -1.75)] for the anterior approach with sternotomy. The instrument manubrial thoracic distance measurements for C5/C6, C6/C7, and T1/T2 also showed nonoverlapping 95% confidence intervals for the transverse cervical versus the anterior approach with sternotomy for the C7/T1 exposure. For the T1/T2 exposure, all four instrument manubrial thoracic distance measurements again showed statistically significant differences between approaches, with nonoverlapping 95% confidence intervals and a statistical power of 1. In addition, the measurements elaborating the anterior-to-posterior distance of the thoracic outlet and the measurements of the angle between the planes of the intervertebral disc and the sternum also showed statistically significant differences between approaches for the T1/T2 segment, with a statistical power of at least 0.9.

CONCLUSIONS

Strong correlations exist between objective measurements and the choice of surgical approach for anterior spine fusion. Among investigated anatomic relations, the instrument manubrial thoracic distance correlated most reliably with the surgeons' choice of the anterior approach. Such objective measurements represent tools that cervical spine surgeons can use to determine the surgical approach.

Histologic characterization of acute spinal cord injury treated with intravenous methylprednisolone

OBJECTIVE

Many substances have been investigated for attenuation of spinal cord injury after acute trauma; however, pharmacologically only steroid administration has shown clinical benefits. This study attempts to characterize local spinal cord histologic response to human dose equivalent (HDE) intravenous methylprednisolone (MP) administration in a rodent model of acute spinal cord injury.

DESIGN

Forty-eight Sprague-Dawley rats were divided equally into control and experimental groups. Each group was subdivided into eight sets of three animals each, according to postinjury intervals. Paraplegia after lower thoracic laminectomy was achieved using a standardized weight drop technique.

INTERVENTION

Within one hour, experimental animals were treated with HDE MP followed by 23-hour continuous infusion of HDE MP. Spinal cords were harvested at variable intervals postinjury and prepared for histologic/immunohistochemistry examination.

MAIN OUTCOME MEASUREMENTS

Edema, necrosis, and glial fibrillary acidic protein (GFAP) positivity in the specimens from treated/control groups were graded by microscopy and immunohistochemistry staining and compared in a blinded manner by a qualified neuropathologist and senior authors.

RESULTS

Minimal differences were observed between control and MP-treated animals at zero and four hours. At eight hours, increased white matter and medullary edema was evident in control versus MP-treated rats. This trend continued through twelve, sixteen, twenty-four, forty-eight, and seventy-two hours. No difference was observed in the astrocytic response to injury by GFAP immunohistochemistry between the groups.

CONCLUSIONS

Histologically, MP reduces the development of severe edema and preserves spinal cord architecture adjacent to the site of injury. In contrast, MP does not alter the development of spinal cord necrosis or astrocytic response at the zone of injury.

Unilateral transforaminal posterior lumbar interbody fusion (TLIF): indications, technique, and 2-year results

A prospective analysis of consecutive cases of lumbar fusion using the unilateral transforaminal posterior lumbar interbody fusion (TLIF) technique with pedicle screw fixation. The objective of the study was to assess the clinical and radiographic outcome of TLIF and describe the technique and indications in the treatment of degenerative disease of the lumbar spine. Forty patients treated with TLIF for degenerative diseases of the lumbar spine were followed up for a minimum of 2.5 years (mean: 36 months; range: 30-42 months). Twenty-three patients had degenerative disc disease alone, 13 had associated isthmic or degenerative spondylolisthesis, and 4 had recurrent disc herniations at the L4-L5 level. Thirty-six (90%) had solid fusions radiographically at latest follow-up. Seventy-nine percent had excellent or good clinical outcomes. Our patients demonstrated high fusion rates and patient satisfaction.

How to do safe sternal reentry and the risk factors of redo cardiac surgery: a 21-year review with zero major cardiac injury

OBJECTIVES

Resternotomy is a common part of cardiac surgical practice. Associated with resternotomy are the risks of cardiac injury and catastrophic hemorrhage and the subsequent elevated morbidity and mortality in the operating room or during the postoperative period. The technique of direct vision resternotomy is safe and has fewer, if any, serious cardiac injuries. The technique, the reduced need for groin cannulation and the overall low operative mortality and morbidity are the focus of this restrospective analysis.

METHODS

The records of 495 patients undergoing 546 resternotomies over a 21-year period to January 2000 were reviewed. All consecutive reoperations by the one surgeon comprised patients over the age of 20 at first resternotomy: M:F 343:203, mean age 57 years (range 20 to 85, median age 60). The mean NYHA grade was 2.3 [with 67 patients (I), 273 (II), 159 (III), 43 (IV), and 4 (V classification)] with elective reoperation in 94.6%. Cardiac injury was graded into five groups and the incidence and reasons for groin cannulation estimated. The morbidity and mortality as a result of the reoperation and resternotomy were assessed.

RESULTS

The hospital/30 day mortality was 2.9% (95% CI: 1.6%-4.4%) (16 deaths) over the 21 years. First (481), second (53), and third (12) resternotomies produced 307 uncomplicated technical reopenings, 203 slower but uncomplicated procedures, 9 minor superficial cardiac lacerations, and no moderate or severe cardiac injuries. Direct vision resternotomy is crystalized into the principle that only adhesions that are visualized from below are divided and only sternal bone that is freed of adhesions is sewn. Groin exposure was never performed prophylactically for resternotomy. Fourteen patients (2.6%) had such cannulation for aortic dissection/aneurysm (9 patients), excessive sternal adherence of cardiac structures (3 patients), presurgery cardiac arrest (1 patient), and high aortic cannulation desired and not possible (1 patient). The average postop blood loss was 594 mL (95% CI:558-631) in the first 12 hours. The need to return to the operating room for control of excessive bleeding was 2% (11 patients). Blood transfusion was given in 65% of the resternotomy procedures over the 21 years (mean 854 mL: 95% CI 765-945 mL) and 41% over the last 5 years.

CONCLUSIONS

The technique of direct vision resternotomy has been associated with zero moderate or major cardiac injury/catastrophic hemorrhage at reoperation. Few patients have required groin cannulation. In the postoperative period, there was acceptable blood loss, transfusion rates, reduced morbidity, and moderate low mortality for this potentially high risk group.

Experiences with redo aortic valve surgery

OBJECTIVES AND METHODS

Reoperations are an integral part of a cardiac surgeon's practice. We share our experience of 546 reoperations over the last 21 years to January 2000, with the focus directed towards the timing of reoperation, reducing the mortality and morbidity of reoperation and rereplacement aortic valve surgery, and understanding the important risk factors. In addition, the precise technical steps that facilitate careful successful explantation of various devices (allograft, stented and stentless xenografts, and mechanical valves) are detailed.

RESULTS

Optimal planned reoperation before deterioration to New York Heart Association Class III/IV levels and before unfavorable cardiac and comorbidity general system failure occurs has produced low mortality and morbidity as compared with first operation results. However, unfavorable delays and late rereferral result in mortality rates of up to 22% for emergency redo AVR for degenerated bioprostheses.

CONCLUSION

Cardiac surgical units have the opportunity to establish a closer patient-surgeon relationship, which favors, when necessary, the optimal timing of reoperation. Knowledge of the more important risk factors and adherence to specific technical steps at explantation of various devices enhances satisfactory reoperation outcomes.

Allograft aortic root replacement in 418 patients over a span of 15 years: 1985 to 2000

Allograft aortic root replacement for primary aortic valve or ascending aortic root pathology is the favored method of technical implantation. Results in 418 patients over 15 years demonstrate exceedingly low early mortality (<1%), complete eradication of preoperative endocarditis but poor long-term durability in the young age group of 20 years or less.

Postoperatively administered aprotinin or epsilon aminocaproic acid after cardiopulmonary bypass has limited benefit

BACKGROUND

Intraoperative antifibrinolytic treatment with aprotinin and epsilon aminocaproic acid (EACA) has been shown to be effective prophylaxis in the reduction of excessive bleeding after cardiopulmonary bypass operations. This study investigated the effectiveness of both drugs when used as a postoperative treatment of patients showing early signs of increased bleeding.

METHODS

In a double-blind, randomized study, 69 patients with chest drainage of 100 mL or more 1 hour after bypass were treated with aprotinin, EACA, or placebo.

RESULTS

In the first 24 hours postoperatively, neither drug significantly reduced chest drainage or blood transfusion requirements compared with placebo. Median (interquartile) cumulative chest drainage volumes for the first 24 hours postoperatively for the aprotinin, EACA, and placebo groups were 525 (340, 750), 575 (450, 762), and 650 (550, 800) mL, respectively. Among the study patients, 4 undergoing valve operation and treated with aprotinin showed a trend toward less bleeding during the first 12 hours postoperatively compared with 5 valve operation patients who received placebo (p = 0.06). Among all patients, the treatment with aprotinin or EACA failed to reduce levels of D-dimer compared with placebo after treatment, indicating that fibrinolysis was not significantly inhibited.

CONCLUSIONS

Aprotinin or EACA administered in the early postoperative period was ineffective in reducing postoperative bleeding with the exception of a small group of patients having valve operations in whom aprotinin treatment may have shown some benefit.

The homograft aortic valve: a 29-year, 99.3% follow up of 1,022 valve replacements

BACKGROUND AND AIM OF THE STUDY

The study aim was to elucidate the advantages and limitations of the homograft aortic valve for aortic valve replacement over a 29-year period.

METHODS

Between December 1969 and December 1998, 1,022 patients (males 65%; median age 49 years; range: 1-80 years) received either a subcoronary (n = 635), an intraluminal cylinder (n = 35), or a full root replacement (n = 352). There was a unique result of a 99.3% complete follow up at the end of this 29-year experience. Between 1969 and 1975, homografts were antibiotic-sterilized and 4 degrees C stored (124 grafts); thereafter, all homografts were cryopreserved under a rigid protocol with only minor variations over the subsequent 23 years. Concomitant surgery (25%) was primarily coronary artery bypass grafting (CABG; n = 110) and mitral valve surgery (n = 55). The most common risk factor was acute (active) endocarditis (n = 92; 9%), and patients were in NYHA class II (n = 515), III (n = 256), IV (n = 112) or V (n = 7).

RESULTS

The 30-day/hospital mortality was 3% overall, falling to 1.13 +/- 1.0% for the 352 homograft root replacements. Actuarial late survival at 25 years of the total cohort was 19 +/- 7%. Early endocarditis occurred in two of the 1,022 patient cohort, and freedom from late infection (34 patients) actuarially at 20 years was 89%. One-third of these patients were medically cured of their endocarditis. Preservation methods (4 degrees C or cryopreservation) and implantation techniques displayed no difference in the overall actuarial 20-year incidence of late survival endocarditis, thromboembolism or structural degeneration requiring operation. Thromboembolism occurred in 55 patients (35 permanent, 20 transient) with an actuarial 15-year freedom in the 861 patients having aortic valve replacement +/- CABG surgery of 92% and in the 105 patients having additional mitral valve surgery of 75% (p = 0.000). Freedom from reoperation from all causes was 50% at 20 years and was independent of valve preservation. Freedom from reoperation for structural deterioration was very patient age-dependent. For all cryopreserved valves, at 15 years, the freedom was 47% (0-20-year-old patients at operation), 85% (21-40 years), 81% (41-60 years) and 94% (>60 years). Root replacement versus subcoronary implantation reduced the technical causes for reoperation and re-replacement (p = 0.0098).

CONCLUSION

This largest, longest and most complete follow up demonstrates the excellent advantages of the homograft aortic valve for the treatment of acute endocarditis and for use in the 20+ year-old patient. However, young patients (< or = 20 years) experienced only a 47% freedom from reoperation from structural degeneration at 10 years such that alternative valve devices are indicated in this age group. The overall position of the homograft in relationship to other devices is presented.

Comparison of epsilon aminocaproic acid and low-dose aprotinin in cardiopulmonary bypass: efficiency, safety and cost

BACKGROUND

In this study we compared the clinical efficiency, safety, and economic benefit of low-dose aprotinin with epsilon aminocaproic acid (EACA) in reducing bleeding after cardiopulmonary bypass operation.

METHODS

In a double-blind, randomized study, 100 patients received low-dose aprotinin (2 x 10(6) kallikrein inhibitor units) or EACA (20 g). The surgical procedure was single- or double-valve replacement with or without coronary artery bypass grafts.

RESULTS

Mediastinal chest drainage and transfusion requirements with both therapies were similar. There were no urgent reoperations to secure hemostasis in either group. Similar levels of D-dimer with both therapies indicate a similar inhibition of fibrinolysis. Release of troponin I was less in the low-dose aprotinin group 1 and 4 hours after bypass, although electrocardiographic measurements did not reflect this difference. Levels of S-100beta and neuron-specific enolase were similar with both therapies, confirming that there was no difference in the occurrence of any adverse neurologic events in either group.

CONCLUSIONS

Low-dose aprotinin and EACA showed similar effects on the reduction of intraoperative and postoperative bleeding. The lower cost of EACA with no change in safety outcome suggests it is the preferred treatment.

Transpecies heart valve transplant: advanced studies of a bioengineered xeno-autograft

BACKGROUND

Tissue engineering approaches utilizing biomechanically suitable cell-conductive matrixes should extend xenograft heart valve performance, durability, and growth potential to an extent presently attained only by the pulmonary autograft. To test this hypothesis, we developed an acellular, unfixed porcine aortic valve-based construct. The performance of this valve has been evaluated in vitro under simulated aortic conditions, as a pulmonary valve replacement in sheep, and in aortic and pulmonary valve replacement in humans.

METHODS

SynerGraft porcine heart valves (CryoLife Inc, Kennesaw, GA) were constructed from porcine noncoronary aortic valve cusp units consisting of aorta, noncoronary aortic leaflet, and attached anterior mitral leaflet (AML). After treatment to remove all histologically demonstrable leaflet cells and substantially reduce porcine cell-related immunoreactivity, three valve cusps were matched and sewn to form a symmetrical root utilizing the AML remnants as the inflow conduit. SynerGraft valves were evaluated by in vitro hydrodynamics, and by in vivo implants in the right ventricular outflow tract of weanling sheep for up to 336 days. Cryopreserved allograft valves served as control valves in both in vitro and in vivo evaluations. Valves were also implanted as aortic valve replacements in humans.

RESULTS

In vitro pulsatile flow testing of the SynerGraft porcine valves demonstrated excellent valve function with large effective orifice areas and low gradients equivalent to a normal human aortic valve. Implants in sheep right ventricular outflow tracts showed stable leaflets with up to 80% of matrix recellularization with host fibroblasts and/or myofibroblasts, and with no leaflet calcification over 150 days, and minimal deposition at 336 days. Echocardiography studies showed normal hemodynamic performance during the implantation period. The human implants have proven functional for over 9 months.

CONCLUSIONS

A unique heart valve construct has been engineered to achieve the equivalent of an autograft. Short-term durability of these novel implants demonstrates for the first time the possibility of an engineered autograft.

The stentless xenograft aortic valve: The wheel turns around

BACKGROUND

A brief overview of the historical pathways of both stented and stentless porcine xenografts is presented in order to understand the return to and continuing clinical use of stentless devices. In addition, 7-11 years of durability with various models of stentless porcine valves has now accumulated and is beginning to be of relevance in determining the future place of this xenograft. Stentlessness and anticalcium agents, coupled with the poor results of stented xenografts in certain patient groups, have led to a resurgence of the clinical use of stentless xenograft valves for aortic valve replacement. An overview of the present state and future of stentless valves is given.

METHODS

At both The Prince Charles Hospital and St Andrew's War Memorial Hospital, Queensland, Australia, 307 patients have received the Model 300 CryoLife-O'Brien stentless composite aortic xenograft from December 1992 to February 2000. Associated procedures were required in 56% of patients (mostly coronary artery bypass, mean 2.4 grafts, in 144 patients (47%) and left ventricular myomectomy in 34 patients (11%)).

RESULTS

The hospital mortality (four early deaths) has been 1.3 +/- 1% (CL 95%) and the follow-up 100% for this analysis. The mean patient age was 73 years (range 57-89 years with 16% being 80 years and over). Morbid events have included six perivalvar leaks: four trivial and identified only on echo Doppler (no clinical murmurs) and two patients requiring reoperation at 10 days and 12 weeks with simple successful repair verified on subsequent echocardiograms. Of the 307 patients over the 7 year period, three valves only have been explanted, two for endocarditis at 1.5 and 3.5 years and one for possible technically induced structural failure at 15 months (probable needle damage). With this exception, there has been as yet no other intrinsic leaflet failure. Four early thromboembolic events (4 days-5 weeks) in patients with atrial fibrillation (no anticoagulants used postoperatively with the first 80 patients) constituted the important early morbid events. Late mortality of this elderly patient cohort has occurred in 27 patients over 7 years of maximum follow-up. One death (endocarditis) has been valve related at 5 years. Serial echocardiography (some 700 echoes in the study of this valve) has demonstrated a mean gradient of 7-9 mmHg with a very low incidence of trivial incompetence (96%) on Doppler examination with implant valve sizes ranging from 21 to 29 mm. One patient had significant regurgitation requiring reoperation. There has been no progression of either incompetence or stenosis of the remaining patients in this follow-up, now into the eighth postoperative year.

CONCLUSION

The early and intermediate results appear excellent in this elderly patient cohort. Nevertheless, important surveillance is obviously required to determine the durability at 10-12 years, a crucial time when stented porcine xenografts began to show an obvious failure rate from structural deterioration, in the middle and elderly aged patient cohort. An attempt is made to outline the future of this type of stentless xenograft and to justify that its cautious use should probably be extended down to the over 50 year age patient cohort.

Pedicle morphology in thoracic adolescent idiopathic scoliosis: is pedicle fixation an anatomically viable technique?

STUDY DESIGN

A radiographic study of thoracic pedicle anatomy in a group of adolescent idiopathic scoliosis (AIS) patients.

OBJECTIVE

To investigate the anatomic constraints of the thoracic pedicles and determine whether the local anatomy would routinely allow pedicle screw insertion at every level.

SUMMARY OF BACKGROUND DATA

In spite of the clinical successes reported with limited thoracic pedicle screw-rod constructs for thoracic AIS, controversy exists as to the safety of this technique.

MATERIAL AND METHODS

Twenty-nine patients with right thoracic AIS underwent preoperative thoracic CT scans and plain radiographs. Anatomic parameters were measured from T1 to T12.

RESULTS

Information on 512 pedicles was obtained. The transverse width of the pedicles from T1 through T12 ranged from 4.6-8.25 mm. The medial pedicle to lateral rib wall transverse width from T1 through T2 ranged from 12.6 to 17.9 mm. Measured dimensions from the CT scans showed the actual pedicle width to be 1-2 mm larger than would have been predicted from the plain radiographs. Age, Risser grade, curve magnitude, and the amount of segmental axial rotation did not correlate with the morphology or size of the thoracic pedicles investigated. In no case would pedicle morphology have precluded the passage of a pedicle screw.

CONCLUSION

Based on the data identified in this group of adolescent patients, it is reasonable to consider pedicle screw insertion at most levels and pedicle-rib fixation at all levels of the thoracic spine during the treatment of thoracic AIS.

Late complications of tissue glues in aortic surgery

BACKGROUND

Tissue glues are used in cardiothoracic surgery as an adjunct to operative procedures where tissues are frail, as in aortic dissection, or where added hemostasis is required. This study was undertaken to review the use of tissue glue in our institution over a 5.5-year period. The aim of the study was to identify any potentially glue-related complications.

METHODS

A review of tissue glue use for the period from January 1993 to September 1998 was performed and pre-, intra-, and postoperative parameters were collected. After some unusual surgical findings, of special interest was a range of pathology found at late reoperation.

RESULTS

A total of 67 cases of tissue glue use were identified, with the majority of operations for type A dissection (76%). There were two intraoperative deaths. Twenty-seven of 65 patients (41%) required 29 further open chest operations; of these, 17 were for acute problems of bleeding or tamponade. Twelve patients (18%) underwent late reoperations months to years later. Nine of these patients, concentrated in two operative groups (7 patients with aortic valve resuspension and 2 patients who had undergone "switch" operations for transposition of great vessels), displayed complications related to the application of gelatin-resorcinol-formaldehyde (GRF) tissue glue.

CONCLUSIONS

Indications for tissue glues in cardiothoracic surgery must be carefully considered. We have reviewed our use of some tissue glues in acute type A aortic dissections and in pediatric cardiac patients and have discontinued the use of GRF glues because of unsatisfactory long-term complications.

The SynerGraft valve: a new acellular (nonglutaraldehyde-fixed) tissue heart valve for autologous recellularization first experimental studies before clinical implantation

The durability of current bioprosthetic heart valves is diminished by glutaraldehyde-associated leaflet calcification or by the associated absence of a cellular component capable of repair of wear-related damage. As a novel tissue engineering approach to improving replacement heart valve durability, we have developed a decellularization process to replace the use of cross-linking to limit xenograft antigenicity. The effectiveness of this process was assessed in a weanling sheep right ventricular outflow tract reconstruction model where valve function, calcification, and recellularization were examined. Porcine aortic valves were decellularized by a process designed to remove all histologically demonstrable leaflet cells. Stentless, bioprosthetic valves were fabricated from acellular tissues, cryopreserved, sterilized, and then implanted as pulmonary valve replacements in 4- to 6-month old female Suffolk sheep. Sheep aortic valves were implanted as allograft control subjects. After 150 days, the grafts were explanted and assessed histologically and by atomic absorption spectrophotometry for calcium content. All valves were hemodynamically functional at explant. Histological examination showed intact leaflets with in-growth of host fibroblastoid cells in all explanted porcine valves and no evidence of calcification. Porcine leaflet calcium content was unchanged over the duration of the implant (1.0+/-1.2 vs 1.5+/-1.8 mg/g dry weight, P = ns). Decellularization can stabilize xenogenic heart valves. Lack of calcification of acellular aortic leaflets suggests that prolonged durability of such valves is attainable without the use of cross-linking agents. The repopulation of the leaflet matrix offers additional promise of durability based on revitalization of the graft in vivo.

An exceedingly low operative mortality given by stentless autologous, homologous, and heterologous aortic valves for aortic valve replacement

Homologous, autologous, and heterologous stentless valves were implanted into 663 patients undergoing aortic valve replacement by standard conventional methods. An exceedingly low mortality rate was achieved for the whole series, with the last consecutive 311 patients experiencing zero mortality. This analysis encompasses the hospitals' total experiences with these three stentless valves and examines only the low and zero mortalities. The three stentless valves were the aortic allograft used as a root replacement in 374 patients (mean age 43 years, 8.8% for active endocarditis), the pulmonary autograft used as a root replacement (22 patients, mean age 34 years) and the Cryolife O'Brien Model 300 stentless composite porcine glutaraldehyde-preserved aortic xenograft (267 patients, mean age 73 years, 16% 80 years or older, 55% concomitant procedures). Overall mortality rate was 1.1%. The seven deaths were essentially non-valve- and non-procedure-related. Of the last consecutive 311 patients, the mortality rate has been zero (166 allografts, 22 autografts, and 123 stentless xenografts). As a result of a careful, planned introduction of each valve and good experience and training in implant techniques, this low mortality and consecutive zero mortality suggest a "modern-day gold standard."

Mesenteric cysts--a series of six cases with a review of the literature

BACKGROUND

Symptomatic mesenteric cysts account for only 1 in 100,000 acute adult and 1 in 20,000 acute paediatric admissions. Acute symptoms are related to compression of intra-abdominal organs or stretching of the mesentery by rapid expansion. An abdominal mass, mobile in transverse but not longitudinal plane, is often the only physical finding.

METHOD

We outline the presentation, management and histological findings of 6 cases that presented to this hospital from 1987-1997.

RESULTS

There were 5 adults aged 32-79 yr and an 8 yr old boy. The child presented acutely with a painful tender abdominal mass. Of the adults, 1 presented acutely, 2 with chronic symptoms and 2 were incidental findings. Mesenteric cysts were successfully resected in all cases.

CONCLUSION

Surgical intervention is recommended and resection of adjacent bowel may be necessary for complete excision. Successful minimal access surgery via the laparoscope has been reported and may become more widely applicable.