Radical excision of intramedullary spinal cord tumors: surgical morbidity and long-term follow-up evaluation in 164 children and young adults

OBJECT

The majority of intramedullary spinal cord tumors (IMSCT) in children and young adults are low-grade gliomas. Radical resection of similar tumors in the cerebral hemisphere or cerebellum is usually curative; however, the conventional management for IMSCTs remains partial resection followed by radiotherapy because of the concern for surgical morbidity. Nevertheless, radical resection of IMSCTs without routine adjuvant treatment has been the rule at our institution since 1980. In an attempt to resolve this controversy, the long-term morbidity and survival in a large series of children have been retrospectively reviewed.

METHODS

The database records and current status of 164 patients 21 years of age and younger in whom an IMSCT was resected were reviewed. A gross-total resection (>95%) was achieved in 76.8% of the surgical procedures. Subtotal resections (80-95%) were performed in 20. 1%. The majority of patients (79.3%) had histologically low-grade lesions. There were no deaths due to surgery. When comparing the preoperative and 3-month postoperative functional grades, 60.4% stayed the same, 15.8% improved, and 23.8% deteriorated. Only 13 patients deteriorated by more than one functional grade. Patients with either no deficits or only mild deficits before surgery were rarely injured by the procedure, reinforcing the importance of early diagnosis and treatment. The major determinant of long-term patient survival was histological composition of the tumor. The 5-year progression-free survival rate was 78% for patients with low-grade gliomas and 30% for those with high-grade gliomas. Patients in whom an IMSCT was only partially resected (<80%) fared significantly worse.

CONCLUSIONS

The long-term survival and quality of life for patients with low-grade gliomas treated by radical resection alone is comparable or superior to minimal resection and radiotherapy. The optimum therapy for patients with high-grade gliomas is yet to be determined.

Planning by older mothers for the future care of offspring with serious mental illness

OBJECTIVE

This study examined permanency planning by older mothers for their adult offspring with long-term mental illness, including extent of residential and financial planning, desire for future family care, and perceived need for and use of services to assist with planning.

METHODS

Mail surveys were completed by 157 mothers (mean age, 67 years) from 41 states who lived with and provided care to adult offspring with serious mental disorders (mean age, 38 years). The offspring were mostly males (76 percent) and had diagnoses primarily of schizophrenia or schizoaffective disorder (60 percent), multiple diagnoses (20 percent), or bipolar disorder (16 percent).

RESULTS

Only 11 percent of mothers reported definite plans for their offspring's future residence, and many had done little or no planning. Three-quarters of respondents hoped that another family member would assume care, yet only one-quarter thought such arrangements would definitely occur. Two-thirds of the respondents had completed financial plans. Although more than two-thirds expressed the need for services to help with planning, less than one-third had used such services. More than half reported awareness of age-related changes in themselves or their spouse as the primary reason for planning.

CONCLUSIONS

Older parents of adults with long-term mental illness need professional help with planning for their offspring's future. This assistance should focus on mechanisms such as estate planning to enable case management and other services after parents' death. The involvement of nondisabled siblings in planning should also be encouraged.

Endovascular repair of abdominal aortic aneurysms: eligibility rate and impact on the rate of open repair

OBJECTIVE

The purpose of this study was to determine the rate of eligibility among patients with abdominal aortic aneurysms (AAAs) considered for endovascular repair and to examine the effect of an endovascular program on the institutional pattern of AAA repair.

METHODS

All patients evaluated for endovascular AAA repair since the inception of an endovascular program were reviewed for determination of eligibility rates and eventual treatment. Open AAA repairs were categorized as simple (uncomplicated infrarenal), complex (juxtarenal, suprarenal, thoracoabdominal, infected), or ruptured, and their rates before and after initiation of an endovascular program were compared.

RESULTS

Over 3 years, 324 patients were considered for endovascular AAA repair; 176 (54%) were candidates, 138 (43%) were not candidates, and 10 (3%) did not complete the evaluation. The rate of eligibility increased significantly from 45% (66/148 patients) during the first half of this period to 63% (110/176 patients) during the second half (P <. 001). Candidates were significantly younger (74.4 +/- 7.6 years) than noncandidates (78.3 +/- 6.7 years) (P <.01), and their aneurysm diameter tended to be smaller (57.6 +/- 9.2 mm compared with 60.8 +/- 12.3 mm; P =.06). The most common reason for ineligibility was an inadequate proximal aortic neck. Of 176 candidates, 78% underwent endovascular repair, and 6% underwent open repair. Of 138 noncandidates, 56% underwent surgical repair. Over a period of 6 years, 542 patients with AAAs (429 simple, 86 complex, 27 ruptured) underwent open repair. The total number and ratio of simple to complex open repairs for nonruptured aneurysms during the 3 years before the initiation of the endovascular program (213 simple, 44 complex) were not significantly different from the repairs over the subsequent 3-year period (216 simple, 42 complex). Similarly, no difference in the total number and the ratio of simple to complex open repairs was found between the first and the second 18-month periods since the initiation of the endovascular program.

CONCLUSIONS

The rate of eligibility of patients with AAA for endovascular repair appears to be higher than previously reported. The presence of an active endovascular program has not decreased the number or shifted the distribution of open AAA repair.

A prospective randomized trial comparing 6 versus 12 prostate biopsy cores: impact on cancer detection

PURPOSE

Several studies suggest that sextant transrectal ultrasound guided biopsy of the prostate provides insufficient material to detect all clinically important prostate cancer, and obtaining more biopsy cores may improve the cancer detection rate. We performed a prospective randomized trial comparing 6 to 12 prostate biopsy cores to determine the impact on the cancer detection rate.

MATERIALS AND METHODS

We prospectively randomized 244 men, including 71 (29%) black men, with a mean age plus or minus standard deviation of 65 +/- 8 years to undergo biopsy with 6 or 12 peripheral zone tissue cores. In our study subjects serum total prostate specific antigen (PSA) was between 2.5 and 20 ng./ml., and/or digital rectal examination was suspicious for cancer. All men completed a self-administered pre-biopsy and 2 post-biopsy questionnaires at 2 and 4 weeks. Cancer detection rates were compared in the groups and correlated with race, biopsy history, digital rectal examination findings, total PSA, transrectal ultrasound volume and PSA density, as determined by the formula, total PSA/transrectal ultrasound volume.

RESULTS

The cancer detection rate in the 6 and 12 core groups was almost identical (26% and 27%, p = 0.9). There was no significant difference in cancer detection in the 2 trial arms with respect to subject race, biopsy history, digital rectal examination findings, total PSA, transrectal ultrasound volume or PSA density. However, our study did not have the statistical power to rule out small differences.

CONCLUSIONS

The overall cancer detection rate is not materially increased by 12 core, peripheral zone biopsy in men in whom prostate cancer was mainly detected by screening.

Inflammatory aneurysm and neurocysticercosis: further evidence for a causal relationship? Case report

OBJECTIVE AND IMPORTANCE

Two cases of inflammatory aneurysms in patients with neurocysticercosis have been reported previously. Clinical and radiographic studies suggest a causal relationship.

CLINICAL PRESENTATION

A man with neurocysticercosis presented with an acute subarachnoid hemorrhage from a left middle cerebral artery aneurysm.

INTERVENTION

The patient underwent a craniotomy and clipping of his aneurysm. Diffuse inflammatory changes and multiple cysticercal cysts were found throughout the left sylvian fissure.

CONCLUSION

The patient had an uneventful recovery. Angiography suggested an inflammatory rather than a congenital aneurysm. Although rare, neurocysticercosis may induce aneurysm formation in the appropriate setting.

Mitral annular dynamics during rapid atrial pacing

INTRODUCTION

Ovine mitral annular area (MAA) reduction predominantly occurs before ventricular systole. We used the myocardial marker methods to investigate left atrial and MAA dynamics during rapid atrial pacing.

METHODS

Seven sheep underwent implantation of 21 myocardial markers around the mitral annulus, the left ventricle and left atrium. After 7 to 10 days, animals were studied with biplane videofluoroscopy to determine 3-dimensional marker coordinates unpaced and during rapid atrial pacing at 140 minutes(-1). Left ventricle volume, left atrial volume (LAV), and MAA were calculated from marker coordinates. End diastole (ED) was defined at peak of the electrocardiogram R wave; times of minimum MAA and minimum LAV were expressed relative to ED (t = 0). Percent reduction in MAA and LAV were calculated from maximum and minimum values between diastole and early systole.

RESULTS

The time of minimum MAA occurred earlier relative to ED during rapid pacing compared with control (-48 +/- 21 vs 19 +/- 14 msec; P <.001), as did the time of minimum LAV (-47 +/- 18 vs 4 +/- 16 msec; P <.001). Minimum MAA and LAV were significantly smaller with rapid pacing (6. 8 +/- 0.6 vs 6.5 +/- 0.5 cm(2); P <.05, respectively; and 15.4 +/- 2. 4 vs 16.5 +/- 2.3 mL; P <.01, respectively), and a relatively greater fractional reduction in MAA and LAV was observed during presystole.

CONCLUSIONS

Rapid atrial pacing resulted in greater MAA and LAV reduction, both of which occurred entirely during diastole. This study supports the notion that MAA reduction is closely linked to LA dynamics.

Alzheimer's disease comorbidity in normal pressure hydrocephalus: prevalence and shunt response

The clinical impact of Alzheimer's disease pathology at biopsy was investigated in 56 cognitively impaired patients undergoing shunt surgery for idiopathic normal pressure hydrocephalus (NPH). Cognition was measured by means of the global deterioration scale (GDS), the mini mental status examination (MMSE) and a battery of six psychometric tests. Gait was assessed using objective measurements of velocity and the ambulatory index (AI). The prevalence of cases exhibiting neuritic plaques (positive biopsies) increased in parallel with dementia severity from 18% for patients with GDS 3 to 75% for patients with GDS scores > or =6. Patients with positive biopsies were more cognitively impaired (higher GDS and lower MMSE scores) as well as more gait impaired (higher AI scores and slower velocities) than patients with negative biopsies. After surgery, gait velocity and AI scores improved significantly and to a comparable degree for patients with and without positive biopsies. Similar proportions of positive and negative biopsy patients also had improved gait as assessed by means of subjective video tape comparisons. There were no significant differences between the biopsy groups in the magnitude of postoperative psychometric change or in the proportion of cases exhibiting improved urinary control. Alzheimer's disease pathology is a common source of comorbidity in older patients with idiopathic NPH where it contributes to the clinical impairment associated with this disorder. For patients accurately diagnosed with NPH, concomitant Alzheimer's disease pathology does not strongly influence the clinical response to shunt surgery.

Hypoxic effects on growth of Palaemonetes vulgaris larvae and other species: Using constant exposure data to estimate cyclic exposure response

First stage larval marsh grass shrimp, Palaemonetes vulgaris, were exposed to patterns of diurnal, semidiurnal, and constant hypoxia to evaluate effects on growth and to determine if there was a consistent relationship between exposures. A comparison of growth with cyclic exposures versus constant low dissolved oxygen (D.O.) concentrations equivalent to the minima of the cycles showed the cyclic exposures resulted in less growth impairment than constant low-D.O. exposures, when compared to saturated controls. The mean extent of growth impairment of cyclic hypoxia was, however, almost 1.5 times more than would be estimated using an arithmetic time-weighted-average of the hypoxic portion of the cycle. Additional testing with other life stages and species resulted in similar patterns of response. Based on this relationship, an adjusted time-weighted-average could be used to estimate field related responses to cyclic dissolved oxygen from laboratory-derived constant exposure data.

Surgical pathology of intramedullary spinal cord neoplasms

The surgical pathology of intramedullary spinal cord neoplasms is most accurately based on radical resection specimens rather than on small biopsies, which may be highly misleading. A review of the neuropathology files at NYU Medical Center revealed 294 surgical specimens of intramedullary cord lesions examined between January 1, 1991 and December 31, 1998. Of these 117 were from children (age less than 21 years) and 177 were from adults (21 and over). While most types of central nervous system tumors known to occur in the brain also occur in the spinal cord, the different proportions of these tumors by histologic type, and the differences in the proportions of tumor types in children compared to adults, are both significant. In adults ependymomas are the predominant tumor type (93 total) while in children astrocytomas and mixed neuronal-glial tumors are virtually equally common and outnumber ependymomas. In this period no cord Primitive Neuroectodermal Tumors were identified. Among the astrocytic neoplasms and other gliomas, high grade tumors were distinctly uncommon in children and only slightly more common in adults, in sharp contrast with the brain, where the majority of adult intra-axial tumors are high grade.

Ring annuloplasty prevents delayed leaflet coaptation and mitral regurgitation during acute left ventricular ischemia

OBJECTIVE

Incomplete mitral leaflet coaptation during acute left ventricular ischemia is associated with end-diastolic mitral annular dilatation and ischemic mitral regurgitation. Annular rings were implanted in sheep to investigate whether annular reduction alone is sufficient to prevent mitral regurgitation during acute posterolateral left ventricular ischemia.

METHODS

Radiopaque markers were inserted around the mitral anulus, on papillary muscle tips, and on the central meridian of both mitral leaflets in three groups of sheep: control (n = 5), Physio ring (n = 5) (Baxter Cardiovascular Div, Santa Ana, Calif), and Duran ring (n = 6) (Medtronic Heart Valve Div, Minneapolis, Minn). After 8 +/- 1 days, animals were studied with biplane videofluoroscopy before and during left ventricular ischemia. Annular area was calculated from 3-dimensional marker coordinates and coaptation defined as minimal distance between leaflet edge markers.

RESULTS

Before ischemia, leaflet coaptation occurred just after end-diastole in all groups (control 17 +/- 41, Duran 33 +/- 30, Physio 33 +/- 24 ms, mean +/- SD, P >.2 by analysis of variance). During ischemia, regurgitation was detected in all control animals, and leaflet coaptation was delayed to 88 +/- 8 ms after end-diastole (P =.02 vs preischemia). This was associated with increased end-diastolic annular area (8.0 +/- 0.9 vs 6.7 +/- 0.6 cm(2), P =.004) and septal-lateral annular diameter (2.9 +/- 0.1 vs 2.5 +/- 0.1 cm, P =.02). Mitral regurgitation did not develop in Duran or Physio sheep, time to coaptation was unchanged (Duran 25 +/- 25 ms, Physio 30 +/- 48 ms [both P >.2 vs preischemia]), and annular area remained fixed.

CONCLUSION

Mitral annular area reduction and fixation with an annuloplasty ring eliminated delayed leaflet coaptation and prevented mitral regurgitation during acute left ventricular ischemia after ring implantation.

Tyrosine phosphorylation of CpsD negatively regulates capsular polysaccharide biosynthesis in streptococcus pneumoniae

In Streptococcus pneumoniae, the first four genes of the capsule locus (cpsA to cpsD) are common to most serotypes. By analysis of various in-frame deletion and site-directed mutants, the function of their gene products in capsular polysaccharide (CPS) biosynthesis was investigated. We found that while CpsB, C and D are essential for encapsulation, CpsA is not. CpsC and CpsD have similarity to the amino-terminal and carboxy-terminal regions, respectively, of the autophosphorylating protein-tyrosine kinase Wzc from Escherichia coli. Alignment of CpsD with Wzc and other related proteins identified conserved Walker A and B sequence motifs and a tyrosine rich domain close to the carboxy-terminus. We have shown that CpsD is also an autophosphorylating protein-tyrosine kinase and that point mutations in cpsD affecting either the ATP-binding domain (Walker A motif) or the carboxy-terminal [YGX]4 repeat domain eliminated tyrosine phosphorylation of CpsD. We describe, for the first time, the phenotypic impact of these two mutations on polysaccharide production and show that they affect CPS production differently. Whereas a mutation in the Walker A motif resulted in loss of encapsulation, mutation of the tyrosines in the [YGX]4 repeat domain resulted in an apparent increase in encapsulation and a mucoid phenotype. These data suggest that autophosphorylation of CpsD at tyrosine attenuates its activity and reduces the level of encapsulation. Additionally, we demonstrated that CpsC is required for CpsD tyrosine phosphorylation and that CpsB influences dephosphorylation of CpsD. These results are consistent with CpsD tyrosine phosphorylation acting to negatively regulate CPS production. This has implications for the function of CpsC/CpsD homologues in both Gram-positive and Gram-negative bacteria and provides a mechanism to explain regulation of CPS production during pathogenesis.

Cerebral vasculopathy secondary to leptomeningeal gliomatosis: angiography

We describe a young woman with a glioblastoma multiforme in whom angiography showed multiple intracranial stenoses. The resected tumour was found to be invading cerebral vessels.

Incidence of p14ARF gene deletion in high-grade adult and pediatric astrocytomas

The INK4a-ARF locus encodes 2 separate proteins through differential splicing of alternative first exons to produce p16INK4a (exon 1alpha) and p14ARF (exon 1beta) products in human cells. The p16INK4a protein inhibits the cyclin D-dependent kinases (CDK) that control the phosphorylation of the Rb protein and cell proliferation. The p14ARF gene product can complex with and sequester the MDM2 protein within the nucleus, thus modulating the activity of the p53 protein. Loss of p16INK4a expression would disrupt the retinoblastoma (Rb)/p16INK4a/cyclin D-dependent kinase (CDK4) pathway, whereas loss of p14ARF expression would inactivate both the Rb and p53/ MDM2/p14ARF pathways through MDM2, which can complex with either Rb or p53. Loss of the p16INK4a gene on 9p21 has been documented in a wide range of human tumors, including one third of glioblastomas. However, in tumors showing homozygous loss of exon 2 of the p16INK4a gene, loss of exon 1beta of the p14ARF gene has not been established. In this study, we have assessed deletion of the p14ARF gene in 29 pediatric and 107 adult high-grade astrocytomas and 9 glioma cell lines, using multiplex PCR analysis for exon 1beta. We found homozygous deletions for exon 1alpha and exon 1beta in 3 of 29 (10%) of the pediatric cases (2 grade III, 1 grade IV), 25 of 107 (23%) of the adult cases (6 grade III and 19 grade IV), and 8 of 9 (89%) of the glioma cell lines. Therefore, loss of the INK4a-ARF locus in high-grade astrocytomas may contribute to the highly malignant behavior and treatment resistance of these tumors through elimination of multiple checkpoint cell cycle control proteins.

Restricted posterior leaflet motion after mitral ring annuloplasty

BACKGROUND

The effects of ring annuloplasty on mitral leaflet motion are incompletely known. The three-dimensional dynamics of the mitral valve in vivo were examined to determine how two types of annuloplasty rings affect leaflet motion during valve closure.

METHODS

Miniature radiopaque markers on the mitral leaflets, annulus, and left ventricle were implanted in three groups of sheep. One group served as control (n = 7); other sheep were randomly assigned to receive either a flexible Duran (n = 6) or a semirigid Carpentier-Edwards Physio ring (n = 6). After recovery, three-dimensional marker coordinates were computed from simultaneous (60 Hz) biplane videofluoroscopic marker images.

RESULTS

Both types of rings immobilized the middle scallop of the posterior leaflet without affecting anterior leaflet motion. The excursion of the anterior leaflet edge from maximally open to fully closed was not different between the groups (control, 13+/-2 mm; Duran 13+/-1 mm; Physio ring, 14+/-1 mm; p > 0.05), but posterior leaflet edge excursion was restricted (control, 7.4+/-0.4 mm; 2.3+/-0.3 mm [p < 0.001]; Physio, 2.7+/-0.2 mm [p < 0.001]) by both rings.

CONCLUSIONS

Mitral annuloplasty with either ring type markedly reduced the mobility of the central posterior leaflet in normal ovine hearts such that valve closure became essentially a single (anterior) leaflet process with the frozen posterior leaflet serving only as a buttress for closing.

Mitral annular dilatation and papillary muscle dislocation without mitral regurgitation in sheep

BACKGROUND

Asymmetrical mitral annular (MA) dilatation and papillary muscle dislocation are implicated in the pathogenesis of functional mitral regurgitation (MR).

METHODS AND RESULTS

To determine the mechanism by which annular and papillary muscle geometric alterations result in MR, we implanted radiopaque markers in the left ventricle, mitral annulus, anterior and posterior mitral leaflets, and papillary muscle tips and bases in 2 groups of sheep. One group served as controls (CTL, n=7); an experimental group (EXP, n=9) underwent topical phenol application to obliterate anterior annular and leaflet muscle (confirmed histologically ex vivo). After 1 week of recovery, markers were imaged with biplane videofluoroscopy, and hemodynamic data were recorded. MA area (computed from 3-dimensional marker coordinates) was 11% to 13% larger in the EXP group than in the CTL group (P<0.05 by ANOVA). This area increase resulted exclusively from intercommissural axis increase except in 1 heart with large (>1 cm) increases in both the intercommissural and septolateral annular axes. The anterior papillary muscle tip in EXP was displaced from CTL by 2.9+/-0.23 mm toward the anterolateral left ventricle and 2.5+/-0.12 mm toward the mitral annulus at end systole; the posterior papillary muscle geometry was unchanged. Transthoracic echocardiography revealed MR only in the heart exhibiting biaxial annular enlargement.

CONCLUSIONS

MA dilatation in the intercommissural dimension with anterior papillary muscle tip displacement toward the annulus is insufficient to produce MR in sheep. Functional MR may require MA dilatation in the septolateral axis, as observed with proximal circumflex coronary occlusion.

Randomized trial of partial versus complete chordal preservation methods of mitral valve replacement: A preliminary report

BACKGROUND

The merits of retaining the subvalvular apparatus during mitral valve replacement for chronic mitral regurgitation have been demonstrated in numerous clinical and laboratory investigations. In this preliminary report, we analyzed the early effects of complete versus partial chordal preservation on left ventricular mechanics.

METHODS AND RESULTS

Fifty patients undergoing isolated surgical correction of mitral insufficiency were prospectively randomized to either total or partial chordal-sparing mitral valve replacement. Of the first 19 patients studied, 8 had preservation of the posterior leaflet only, and 11 had complete preservation of all chordal structures. A comparison group consisted of 6 patients who had primary mitral valve repair. Echocardiography was performed preoperatively and at discharge from the hospital to determine dimensions, wall stress, and ejection fraction. Preservation of the posterior leaflet only resulted in a reduction in end-diastolic volume, an increase in end-systolic volume (P=0.058), a rising trend in end-systolic stress, a decrease in long-axis fractional shortening, and a fall in ejection fraction from 0.68+/-0.16 to 0. 46+/-0.19 (P=0.001). Although patients who had preservation of all chordal structures also had decreased end-diastolic volume, long-axis fractional shortening, and ejection fraction (0.60+/-0.13 to 0.52+/-0.07, P=0.01), end-systolic stress fell and end-systolic volume decreased instead of increased. Compared with the posterior leaflet preservation group, those in the group with completely preserved chordal structures had a larger decline in end-diastolic volume and smaller decreases in long-axis fractional shortening and ejection fraction. Changes in end-systolic volume and stress were also statistically different between the 2 cohorts. No differences were detected between the group with total preserved chordal structures and the mitral repair group in any of the measured parameters.

CONCLUSIONS

Compared with posterior chordal preservation only, complete retention of the subvalvular apparatus during mitral valve replacement resulted in improved ejection performance and smaller chamber volumes due to reduced systolic wall stress. These hemodynamic advantages are comparable to those observed with primary mitral reconstruction.

Deformational dynamics of the aortic root: modes and physiologic determinants

BACKGROUND

Current surgical methods for treating aortic valve and aortic root pathology vary widely, and the basis for selecting one repair or replacement alternative over another continues to evolve. More precise knowledge of the interaction between normal aortic root dynamics and aortic valve mechanics may clarify the implications of various surgical procedures on long-term valve function and durability.

METHODS AND RESULTS

To investigate the role of aortic root dynamics on valve function, we studied the deformation modes of the left, right, and noncoronary aortic root regions during isovolumic contraction, ejection, isovolumic relaxation, and diastole. Radiopaque markers were implanted at the top of the 3 commissures (sinotubular ridge) and at the annular base of the 3 sinuses in 6 adult sheep. After a 1-week recovery, ECG and left ventricular and aortic pressures were recorded in conscious, sedated animals, and the 3D marker coordinates were computed from biplane videofluorograms (60 Hz). Left ventricular preload, contractility, and afterload were independently manipulated to assess the effects of changing hemodynamics on aortic root 3D dynamic deformation. The ovine aortic root undergoes complex, asymmetric deformations during the various phases of the cardiac cycle, including aortoventricular and sinotubular junction strain and aortic root elongation, compression, shear, and torsional deformation. These deformations were not homogeneous among the left, right, and noncoronary regions. Furthermore, changes in left ventricular volume, pressure, and contractility affected the degree of deformation in a nonuniform manner in the 3 regions studied, and these effects varied during isovolumic contraction, ejection, isovolumic relaxation, and diastole.

CONCLUSIONS

These complex 3D aortic root deformations probably minimize aortic cusp stresses by creating optimal cusp loading conditions and minimizing transvalvular turbulence. Aortic valve repair techniques or methods of replacement using unstented autograft, allograft, or xenograft tissue valves that best preserve this normal pattern of aortic root dynamics should translate into a lower risk of long-term cusp deterioration.

Functional evaluation of the medtronic stentless porcine xenograft mitral valve in sheep

BACKGROUND

Recently, renewed interest in allograft and stentless "freehand" bileaflet xenograft mitral valve replacement has arisen. The variability of human papillary tip anatomy and scarcity of donors limit allograft availability, making xenograft mitral valves an attractive alternative; however, these valves require new surgical implantation techniques, and assessment of their hemodynamics and functional geometry is lacking.

METHODS

Seven sheep underwent implantation of a new stentless, glutaraldehyde-preserved porcine mitral valve (Physiological Mitral Valve [PMV], Medtronic) and were studied acutely under open-chest conditions. A new method of retrograde cardioplegia was developed. Hemodynamic valve function was assessed by epicardial Doppler echocardiography. 3D motion of miniature radiopaque markers sutured to the valve leaflets, annulus, and papillary tips was measured. Six other sheep with implanted markers served as controls.

RESULTS

Both papillary muscle tips avulsed in the first animal, leaving 6 other animals. Mitral regurgitation was not observed in any xenograft valve. The peak and mean transvalvular gradients were 4.6+/-1.8 mm Hg and 2.6+/-1.5 mm Hg, respectively. The average mitral valve area was 5.7+/-1.6 cm(2). Valve closure in the xenograft group occurred later (30+/-11 ms, P<0. 015) and at higher left-ventricular pressure (61+/-9 mm Hg, P<0.001) than in the control group; furthermore, leaflet coaptation was displaced more apically (5.6+/-2.2 mm, P<0.001) and septally (5. 8+/-1.5 mm, P<0.001), and the anterolateral papillary tip underwent greater septal-lateral displacement (2.7+/-1.5 mm, P<0.001). Annular contraction during the cardiac cycle was similar in the 2 groups (xenograft 9.2+/-4.5% versus control 10.6+/-4.5% [mean+/-SD; 2-factor ANOVA model]).

CONCLUSIONS

Successful freehand stentless porcine mitral valve implantation is feasible in sheep and was associated with excellent early postoperative hemodynamics. Physiological mitral valve annular contraction and functional leaflet closure mechanics were preserved. Long-term valve durability, calcification, and hemodynamic performance remain to be determined in models.

Effects of mitral valve replacement on regional left ventricular systolic strain

BACKGROUND

Mitral valve replacement (MVR) with chordal excision impairs left ventricular (LV) systolic function, but the responsible mechanisms remain incompletely characterized. Loss of normal annular-papillary continuity also adversely affects LV torsional deformation, possibly due to changes in myocardial fiber contraction pattern.

METHODS

Twenty-seven dogs underwent insertion of LV myocardial markers and a sham procedure (cardiopulmonary bypass, no MVR, n = 6), conventional MVR with chordae tendineae excision (n = 7), or chordal-sparing MVR with reattachment of the anterior leaflet chordae to the anterior annulus (n = 7) or to the posterior annulus (n = 7). In the anterior, lateral, posterior, and septal LV regions, linear chords were constructed from each region's central marker to its surrounding markers. Percent systolic shortening (regional LV strain) was calculated for each chord, and the chords were assigned to one of four angular groups: I, left-handed oblique (subepicardial fiber direction); II, circumferential (midwall); III, right-handed oblique (subendocardial); or IV, longitudinal. Regional LV strain data were compared before and after MVR.

RESULTS

Sham and anterior chordal-sparing MVR had minimal effects on regional LV strain. With posterior chordal-sparing MVR: anteriorly, left-oblique (I) strain fell (31%, p<0.05), as did circumferential (II) and right-oblique (III) strains (by 49% and 51%, respectively; p<0.01). Laterally, left-oblique (I) strain fell by 36% (p<0.05), as did longitudinal (IV) strain (54% decline, p<0.01). Conventional MVR with chordal excision disrupted regional fiber shortening diffusely, affecting oblique fibers (I and III) in the anterior and septal regions and impairing longitudinal (IV) strain in all regions (45% to 68% fall, p<0.05).

CONCLUSIONS

Sham and anterior chordal-sparing MVR did not substantially alter regional LV strain; however, loss of normal anatomic valvular-ventricular integrity (conventional MVR) or posterior chordal-sparing MVR resulted in pronounced alterations in LV strain, most notably in the longitudinal and oblique fiber directions. These findings demonstrate that the deleterious effects of chordal excision are associated with perturbed internal myocardial systolic deformation, which suggests that chordal disruption distorts myofiber architecture or regional systolic loading.

Percutaneous balloon fenestration and stenting for life-threatening ischemic complications in patients with acute aortic dissection

OBJECTIVES

Acute aortic dissection frequently causes life-threatening ischemia of end-organs, historically associated with mortality exceeding 60%. Reperfusion with the use of interventional radiologic methods has evolved as a promising treatment. We report results of our initial 6 years of experience with percutaneous balloon fenestration of the intimal flap and endovascular stenting.

METHODS

Forty patients (32 male and 8 female) with a median age of 53 years (range 16-86 years) underwent percutaneous treatment for peripheral ischemic complications of 10 type A and 30 type B acute aortic dissections since 1991. Twenty patients had ischemia of multiple organ systems. Thirty patients had renal, 22 had leg, 18 had mesenteric, and 1 had arm ischemia.

RESULTS

Fourteen patients were treated with stenting of either the true or false lumen combined with balloon fenestration of the intimal flap, 24 with stenting alone, and 2 with fenestration alone. Successful revascularization was achieved in 93% +/- 4% (+/-70% confidence levels) of patients (37/40). Nine patients had procedure-related complications. The 30-day mortality rate was 25% +/- 7% (10/40), often related to irreversible ischemia of intra-abdominal organs that was present before the procedure. Of the remaining 30 patients, 5 have died and the remaining 25 continue to have relief of ischemic symptoms at a mean follow-up of 29 months.

CONCLUSION

Percutaneous balloon fenestration of the intimal flap and endovascular stenting is an effective treatment for life-threatening ischemic complications of acute aortic dissection.

Glial neoplasms: dynamic contrast-enhanced T2*-weighted MR imaging

PURPOSE

To evaluate the role of T2*-weighted echo-planar perfusion imaging by using a first-pass gadopentetate dimeglumine technique to determine the association of magnetic resonance (MR) imaging-derived cerebral blood volume (CBV) maps with histopathologic grading of astrocytomas and to improve the accuracy of targeting of stereotactic biopsy.

MATERIALS AND METHODS

MR imaging was performed in 29 patients by using a first-pass gadopentetate dimeglumine T2*-weighted echo-planar perfusion sequence followed by conventional imaging. The perfusion data were processed to obtain a color map of relative regional CBV. This information formed the basis for targeting the stereotactic biopsy. Relative CBV values were computed with a nondiffusible tracer model. The relative CBV of lesions was expressed as a percentage of the relative CBV of normal white matter. The maximum relative CBV of each lesion was correlated with the histopathologic grading of astrocytomas obtained from samples from stereotactic biopsy or volumetric resection.

RESULTS

The maximum relative CBV in high-grade astrocytomas (n = 26) varied from 1.73 to 13.7, with a mean of 5.07 +/- 2.79 (+/- SD), and in the low-grade cohort (n = 3) varied from 0.92 to 2.19, with a mean of 1.44 +/- 0.68. This difference in relative CBV was statistically significant (P < .001; Student t test).

CONCLUSION

Echo-planar perfusion imaging is useful in the preoperative assessment of tumor grade and in providing diagnostic information not available with conventional MR imaging. The areas of perfusion abnormality are invaluable in the precise targeting of the stereotactic biopsy.

Endovascular treatment of descending thoracic aortic aneurysms and dissections

Various endovascular techniques have become viable therapeutic alternatives in the treatment of patients with many types of descending thoracic aortic pathology and aortic dissections. Descending thoracic aortic aneurysms can be successfully treated using stent grafts. This technique is less invasive and is associated with acceptable morbidity and mortality rates. Patients who are particularly likely to benefit include the very elderly population; those with markedly compromised cardiac, pulmonary, or renal status; and individuals who have previously undergone complex operations on the thoracic aorta. Other endovascular methods, such as aortic flap fenestration, stent, or covering of the primary intimal tear in the descending thoracic aorta with a stent graft, have also been effectively employed in the treatment of peripheral arterial complications of aortic dissection. Despite the reported early success of these endovascular percutaneous methods, true assessment of the effectiveness of these various techniques awaits long-term follow-up evaluation in large patient populations.

Thoracic aortic aneurysm repair with an endovascular stent graft: the "first generation"

OBJECTIVE

The feasibility and efficacy trial of an endovascular stent-grafting system for the treatment of aneurysms of the descending thoracic aorta was investigated.

METHODS

After Institutional Review Board approval, 103 patients (mean age 69 years) underwent stent graft repair of a descending thoracic aortic aneurysm between July 1992 and November 1997. The stent graft was fabricated using self-expanding "Z" stents covered by a woven Dacron tube graft. Follow-up, which averaged 22 months, was 100% complete. Simultaneous open abdominal aortic aneurysm repair was performed in 19 patients.

RESULTS

Complete aneurysm thrombosis was achieved in 86 patients (83%). Early mortality, defined as a death during the same hospitalization or in less than 30 days, was 9 +/- 3%, and was significantly associated with preoperative cerebrovascular accident (CVA) or myocardial infarction. Major perioperative morbidity occurred in 31 patients, and included paraplegia in 3, CVA in 7, and respiratory insufficiency in 12 patients each. Actuarial survival was 81 +/- 4% at 1 year, and 73 +/- 5% at 2 years. Treatment failure (including all late, sudden, unexplained deaths) occurred in 38 patients, and only 53 +/- 10% of patients were free of treatment failure at 3.7 years. Five patients required late operative therapy for endoleaks associated with aneurysm enlargement.

CONCLUSIONS

Satisfactory results were achieved using this "first-generation" homemade stent graft device. Mortality and morbidity occurred frequently, but may have been associated with the high-risk character of this patient population. Medium-term results were acceptable, but continued aortic enlargement, with the late development of endoleaks, is a significant concern. Second-generation devices with commercial development, coupled with this initial experience, should allow improved clinical results in the future. Longer term follow-up is still necessary to fully define the efficacy of this endovascular approach.

Endovascular stent-graft placement for the treatment of acute aortic dissection

BACKGROUND

The standard treatment for acute aortic dissection is either surgical or medical therapy, depending on the morphologic features of the lesion and any associated complications. Irrespective of the form of treatment, the associated mortality and morbidity are considerable.

METHODS

We studied the placement of endovascular stent-grafts across the primary entry tear for the management of acute aortic dissection originating in the descending thoracic aorta. We evaluated the feasibility, safety, and effectiveness of transluminal stent-graft placement over the entry tear in 4 patients with acute type A aortic dissections (which involve the ascending aorta) and 15 patients with acute type B aortic dissections (which are confined to the descending aorta). Dissections involved aortic branches in 14 of the 19 patients (74 percent), and symptomatic compromise of multiple branch vessels was observed in 7 patients (37 percent). The stent-grafts were made of self-expanding stainless-steel covered with woven polyester or polytetrafluoroethylene material.

RESULTS

Placement of endovascular stent-grafts across the primary entry tears was technically successful in all 19 patients. Complete thrombosis of the thoracic aortic false lumen was achieved in 15 patients (79 percent), and partial thrombosis was achieved in 4 (21 percent). Revascularization of ischemic branch vessels, with subsequent relief of corresponding symptoms, occurred in 76 percent of the obstructed branches. Three of the 19 patients died within 30 days, for an early mortality rate of 16 percent (95 percent confidence interval, 0 to 32 percent). There were no deaths and no instances of aneurysm or aortic rupture during the subsequent average follow-up period of 13 months.

CONCLUSIONS

These initial results suggest that stent-graft coverage of the primary entry tear may be a promising new treatment for selected patients with acute aortic dissection. This technique requires further evaluation, however, to assess its therapeutic potential fully.