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J Thorac Cardiovasc Surg 2004;127:270-272
© 2004 The American Association for Thoracic Surgery
Brief communication |
a Michael E. DeBakey Department of Surgery, Division of Transplant and Assist Devices,, Baylor College of Medicine, Houston, Tex, USA
b Department of Medicine, Section of Cardiology, Baylor College of Medicine, Houston, Tex, USA
Received for publication May 23, 2003; accepted for publication July 14, 2003.
* Address for reprints: Matthias Loebe, MD, PhD, Baylor College of Medicine, Michael. E. DeBakey Department of Surgery, Division of Transplant Surgery and Assist Devices, 6560 Fannin Street, Scurlock Tower, Suite 1860, Houston, TX 77030, USA
mloebe{at}bcm.tmc.edu
Left ventricular outflow obstruction usually requires repair or replacement of the aortic valve or resection of a subannular stenosis. Cooley and Norman1 proposed the implantation of a valve-containing conduit between the apex of the left ventricle and the descending thoracic aorta for treatment of complex outflow obstruction. Following a 5-year follow-up, we report the case of a patient who underwent apicoaortic conduit implantation in 1997.
Clinical summary
The patient had a history of 3 previous aortic valve replacements including replacement of the ascending aorta for repair of prosthetic endocarditis with annular abscess. The need for the implantation of an apicoaortic conduit arose from an enduring hemolysis secondary to a relatively undersized aortic valve prosthesis. In 1975, the then 36-year-old man underwent replacement of a bicuspid stenotic aortic valve with a Björk-Shiley convexo-concave (BSCC) mechanical heart valve (Shiley, Inc, Irvine, Calif, a subsidiary of Pfizer, Inc). In September 1995, the patient had a high fever, chills, fatigue, joint pain, and painful peripheral subcutaneous nodes of the phalanges. Echocardiography revealed a paravalvular leak with fistula to the right ventricle. Blood cultures were positive for Staphylococcus aureus. After prolonged intravenous antibiotic therapy, replacement of the Björk-Shiley valve and repair of the aorta-right ventricular fistula was performed by implantation of a 21-mm St Jude Medical valve (St Jude Medical, St Paul, Minn) with aortic root replacement using a Hemashield graft (Meadox Medicals, Inc, Oakland, NJ). The coronary arteries were reinserted by the Cabrol technique. In October 1996, however, the patient had increasing fatigue, and echocardiography showed severe subvalvular aortic stenosis. The aortic valve area was 0.6 cm2 with a mean pressure gradient of 56 mm Hg and a peak velocity of the stenotic jet of 4.85 m/s. An attempt was made to excise the stenosis through the valve but the valve broke under the stress. After resection of the valve and subvalvular stenosis, a 19-mm St Jude Medical prosthesis was implanted. Subsequently, the patient began to experience hemolysis with consecutive anemia requiring recurrent blood transfusions twice a month. The hemolysis was believed to be secondary to compounding aortic prosthetic and subvalvular stenosis. Therefore, creation of a new left ventricular outflow tract was considered (Table 1).
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The patient has had no further blood transfusions and his hemoglobin remains stable at 11.5 g/dL. There is a decent murmur at the left-ventricular apex and at aortic position. The most recent echocardiography (Figure 1) confirmed a distinct regression in heart dimensions and the hemodynamic calculations resulted in an overall cardiac output of 9.6 L (3.6 L flow through the aortic valve prosthesis and 6 L through the conduit valve).
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Chronic intravascular hemolysis in patients following left-sided heart valve replacement with mechanical prosthesis is well documented.2 However, severe hemolysis is mostly associated with valve malfunction or paravalvular leakage.3 A valve prosthesis/body surface area mismatch can also alter postoperative outcome with regard to incidence of sudden death, decreased left ventricular performance, and hemolysis.4
In the presented case, valve function was normal and there was no evidence of paraprosthetic leakage. Due to the preceding operations, it was decided to implant a 19-mm St Jude Medical aortic valve prosthesis. This resulted, however, in a mismatch between valve size and body surface area and, consequently, in an artificial obstruction of left ventricle outflow.
Cooley and colleagues5 previously reported creation of double-outlet left ventricles in a number of patients with severe left heart outflow tract obstruction. The left lateral transthoracic approach, performed in this case, gives direct access to the descending aorta and makes the operation less complex. In creating this conduit, the surgeon has the choice of biologic or mechanical valves. This patient received a mechanical valve-containing conduit due to the mechanical valve in aortic position. Both the anemia and all hematological alterations disappeared after the operation. The gradient over the aortic valve returned to near-normal values and the left ventricular hypertrophy regressed.
Implantation of an apicoaortic conduit can be considered as a valuable alternative to repeated aortic valve replacements in selected patients with complex stenosis of the left ventricular outflow tract.
Footnotes
Dr Skrabal is supported by a grant of the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG).
References
This article has been cited by other articles:
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  L. N. Girardi, K. H. Krieger, C. A. Mack, and O. W. Isom No-Clamp Technique for Valve Repair or Replacement in Patients With a Porcelain Aorta Ann. Thorac. Surg., November 1, 2005; 80(5): 1688 - 1692. [Abstract] [Full Text] [PDF]
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