Endoluminal graft repair for abdominal aortic aneurysms in high-risk patients and octogenarians: is it better than open repair?

OBJECTIVE

To analyze the short-term and midterm results of open and endoluminal repair of abdominal aortic aneurysms (AAA) in a large single-center series and specifically in octogenarians.

METHODS

Between January 1997 and October 2000, 470 consecutive patients underwent elective repair of AAA. Conventional open repair (COR) was performed in 210 patients and endoluminal graft (ELG) repair in 260 patients. Ninety of the patients were 80 years of age or older; of these, 38 underwent COR and 52 ELG repair.

RESULTS

Patient characteristics and risk factors were similar for both the entire series and the subgroup of patients 80 years or older. The overall complication rate was reduced by 70% or more in the ELG versus the COR groups. The postoperative death rate was similar for the COR and ELG groups in the entire series and lower (but not significantly) in the ELG 80 years or older subgroup versus the COR group. The 36-month rates of freedom from endoleaks, surgical conversion, and secondary intervention were 81%, 98.2%, and 88%, respectively.

CONCLUSION

The short-term and midterm results of AAA repair by COR or ELG are similar. The death rate associated with this new technique is low and comparable, whereas the complication rate associated with COR in all patients and those 80 years or older in particular is greater and more serious than ELG repair. Long-term results will establish the role of ELG repair of AAA, especially in elderly and high-risk patients.

Anomalous ureteral insertion in VATER syndrome complicating renal transplantation

We report a renal transplantation with uretero-ureterostomy to a normal ureter in a patient with VATER syndrome who had agenesis of the ipsilateral kidney. Anomalous insertion of the native ureter into the ejeculatory duct was subsequently identified when his post-operative course was complicated by an ureteric leak and hydronephrosis. To our knowledge, this anomaly has not been previously reported. Transplant function is now excellent following temporary percutaneous nephrostomy. Contrast delineation of genito-urinary anatomy is recommended, before utilizing existing anatomical structures in the urinary tract, in patients with VATER syndrome.

Structure of haptoglobin and the haptoglobin-hemoglobin complex by electron microscopy

The human serum protein, haptoglobin, forms a stable, irreversible complex with hemoglobin. Haptoglobin is composed of two H chains, which are connected via two smaller L chains to give a protein of 85,000 Mr. In the complex, each H chain binds an alpha beta dimer of hemoglobin for a total molecular weight of 150,000. The scanning transmission electron microscope has been used to derive new information about the shape and structure of haptoglobin and hemoglobin, and about their relative orientation in the complex. The micrographs of negatively stained images show that haptoglobin has the shape of a barbell with two spherical head groups, which are the H chains. These are connected by a thin filament with a central knob, which corresponds to the L chains. The overall length of the molecule is about 124(+/- 8) A and the interhead distance is 87 (+/- 7) A. In the haptoglobin-hemoglobin complex, the head groups are ellipsoidal and under optimal staining conditions bilobal . Thus, the alpha beta dimers are binding to the H chains, but off the long axis of the barbell by 127 degrees in a trans configuration. This angle considerably restricts the region on the surface of the H chain structure that can contain the hemoglobin binding site. The interhead group distance for complex is 116.5(+/- 6.3) A or 30 A greater than for haptoglobin. The N terminus of the beta chain was located on the trans off-axis configured barbell structure of complex by using a hemoglobin that was crosslinked between the alpha beta dimers in the region of the beta N terminus. The distances and angles that are measured on the micrographs for the native and crosslinked complex molecules permit the directions of two of the alpha beta dimer ellipsoid axes to be assigned. Taken together, these data provide an approximate relative orientation for the binding of the alpha beta dimer to the H chain of haptoglobin.

Structure and assembly of haptoglobin polymers by electron microscopy

Haptoglobin (Hp) consists of light (L) and heavy (H) chains, the latter of which combine with hemoglobin alpha beta dimers to form a highly stable complex. Human haptoglobin assembles as HL units that occur in two allelic forms; HL1 , which is monovalent, and HL2 , which is divalent. As a result, three phenotypic forms exist in the human population: Hp1-1, the homozygous form in which the monovalent HL1 unit occurs as a dimer; Hp2-2, the homozygous form of the divalent HL2 unit, which gives a series of polymers; and the heterozygous Hp2-1 form, which gives a different series of polymers. We have investigated the structures and assembly properties of these two haptoglobin polymeric series in their complexes with hemoglobin using high-resolution scanning transmission electron microscopy. Polymers of complex are composed of ellipsoidal or bilobal head groups, which are the H alpha beta subunits connected by thin filament-like structures, which are the L chains. Polymers of size up to pentamers can be identified easily by counting the number of head groups in the molecule. Complex 2-1 and complex 2-2 trimers were studied extensively. The differences in detailed morphology show that while the 2-1 trimer is a linear polymer, the 2-2 trimer is a closed circular molecule. The micrograph images suggest that complex 2-2 tetramers and pentamers, and perhaps higher forms may also be cyclic. The structure of the L2 subunit of haptoglobin is shown to be composed of two domains, which may be similar in structure to the single domain of the monovalent L1 chain. The two L2 domains are connected by a hinge that has quite limited flexibility. Using these structural models, assembly characteristics and structural properties of the trimers and tetramers of complex 2-1 and complex 2-2 are described.