Asian Cardiovasc Thorac Ann 1999;7:37-39
© 1999 Asia Publishing EXchange Pte Ltd
Maximum Exercise After Aortic Valve Replacement with Pulmonary Autograft
Donald B Doty, MD,
Jean H Flores, RN,
Frank G Yanowitz, MD,
James H Oury, MD
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Department of Surgery LDS Hospital Salt Lake City, Utah, USA
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For reprint information contact: Donald B Doty, MD Tel: 1 801 322 0563 Fax: 1 801 322 0567 324 Tenth Avenue #160, Salt Lake City, UT 84103, USA.
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Abstract
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Patients describe excellent exercise tolerance after aortic valve replacement with a pulmonary autograft (Ross procedure) but objective data regarding exercise ability has not been available. This report describes testing of maximum exercise performance at least one year after operation. Four athletic males underwent aortic valve replacement with a pulmonary autograft. Exercise to exhaustion was performed on a bicycle ergometer. Measurements of oxygen consumption and echocardiography were carried out. High levels of work energy were achieved (230 to 331 watts). Oxygen consumption increased from a range of 1.7 to 5.1 mL•kg–1•min–1 at rest to 33 to 45.1 mL•kg–1•min–1 at peak exercise. Pressure gradients over the left ventricular outflow tract were calculated by echocardiography as 10 to 14 mm Hg after maximum exercise. These data indicate that high levels of exercise and excellent hemodynamic performance can be achieved after the Ross procedure allowing unrestricted aerobic athletic activities.
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Introduction
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Ross1 described an operation in 1967 in which the autogenous pulmonary valve was used to replace the aortic valve. The pulmonary valve was then replaced with a homograft (allograft). This operation has since been known as the Ross procedure. The operation is based on the fact that the pulmonary valve is nearly identical in structure and function to the aortic valve. The pulmonary annulus diameter actually exceeds that of the natural aortic annulus by approximately 2 mm so when the Ross procedure is performed using the pulmonary trunk for aortic root replacement, there is a slight sizing up of the left ventricular outflow tract. The autogenous pulmonary valve, being viable and the patient's own tissue, should not only have the potential for permanent correction of aortic valve disease but also provide hemodynamic performance superior to any other method of aortic valve replacement.2 Patients describe excellent exercise tolerance after the Ross procedure, however, objective data regarding exercise ability has not been available. This report describes maximum exercise performance in 4 athletic males after aortic valve replacement with a pulmonary autograft.
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Patients and Methods
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Four males had aortic valve replacement with a pulmonary autograft and replacement of the pulmonary valve with a pulmonary homograft (allograft) at least one year before exercise testing. The operations were all performed using the standard aortic root replacement technique.3 Each patient was a conditioned athlete or has worked in an occupation requiring a high degree of physical conditioning (Table 1
). This study was part of a larger one evaluating the Ross procedure by echocardiography after maximum exercise.
Each man was subjected to maximum exercise testing on a bicycle ergometer. The test protocol consisted of measuring oxygen consumption and performing echocardiography at rest. Exercise was started with one minute of free wheeling followed by use of a 30-watt per minute ramp and exercise to exhaustion. Immediately within 90 seconds after achieving maximum exercise, echocardiography was performed with the patient lying down. The neoaortic valve was examined for competence and the pressure gradient across the valve, between the left ventricle and the aorta was calculated by Doppler ultrasound.
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Results
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Maximum exercise to exhaustion was achieved in 614 to 756 seconds. High levels of work energy were produced by each man, ranging from 230 to 331 watts. Heart rates in excess of 180 beats•min–1 were reached in all except one man who was being treated with a beta blocker. Oxygen consumption was raised greatly from resting levels of 1.7 to 5.1 mL•kg–1•min–1 to a range of 33 to 45.1 mL•kg–1•min–1 at peak exercise. The pressure gradient over the left ventricular outflow tract immediately after maximum exercise ranged from 10 to 14 mm Hg (Table 2).
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Discussion
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This study demonstrates that excellent hemodynamic performance can be achieved after aortic valve replacement with a pulmonary autograft (the Ross procedure). Pressure gradients over the neoaortic valves were physiologic at peak exercise in these subjects. Patients may achieve high levels of exercise after the Ross procedure. The classification of cardiovascular fitness using maximum oxygen consumption is based upon data from the Cooper Clinic Coronary Risk Factor Profile Charts.4 When compared to a population of 9607 healthy men aged 40 to 49 years studied at the Cooper Clinic, patient no. 1 was in the 20th percentile fitness category and patient no. 2 was in the 13th percentile; both below average. When compared to a population of 1890 healthy men aged 20 to 29, patient no. 3 was in the 60th percentile and patient no. 4 was in the 65th percentile; both above average.
Since anticoagulant therapy is not required after aortic valve replacement with a pulmonary autograft, there is no need to restrict aerobic physical activity of patients having this operation. It is known that the tensile strength of the pulmonary valve leaflets equals or exceeds that of aortic valve leaflet tissue.5 When the Ross procedure is performed using the entire pulmonary trunk for aortic root replacement, as it is in 74% of operations in current practice, it is likely that the neoaortic root is more distensible than the natural aorta.6 It seems prudent to restrict isometric athletic activities, such as power weight lifting and wrestling, until more is known about the adaptation of the pulmonary artery to systemic pressure. The findings in this study indicate that this operation is of great advantage to individuals seeking high levels of physical activity or athletic competition.
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References
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Ross DN. Replacement of aortic and mitral valves with pulmonary autograft. Lancet 1967;2:956–8.[Medline]
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Ross DN, Jackson M, Davies J. The pulmonary autograft –– a permanent aortic valve. Eur J Cardio-thorac Surg 1992;6:113–7.[Abstract]
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Doty DB. Aortic valve replacement with homograft and autograft. Sem Thorac Cardiovasc Surg 1996;8:249–58.[Medline]
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Pollock ML, Wilmore JH, editors. Exercise in health and disease: evaluation and prescription for prevention and rehabilitation. 2nd edition. Philadelphia: Saunders, 1990:660–71.
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Gorczynski A, Trenkner M, Anisimowicz L, Gutkowski R, Drapella A, Kwiatkowska E, et al. Biomechanics of the pulmonary autograft valve in the aortic position. Thorax 1982;37:535–9.[Abstract/Free Full Text]
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Oury JH. An appraisal of the Ross procedure [editorial]. J Heart Valve Dis 1995;4:350–1.[Medline]
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Abstract
Introduction
