Ross Procedure Sections: Introduction | History | Anatomy | Pros & Cons | Patient Selection | Technique | Results | Pediatric Ross

Pros and Cons

There are many unique advantages to the Ross not available in other aortic valve operations. The length and complexity of the operation also carries some drawbacks. However in certain patients the pulmonary autotransplant is clearly superior to all other surgical treatments for aortic valve disease. To understand the results in detail, it is important to first discuss the results with mechanical, tissue, and homograft replacement of the aortic valve which are the current methods most commonly applied.

The native aortic valve provides an crucial safety barrier for the important, high pressure left heart. A normally functioning aortic valve is essential for life. In situations where the aortic valve is diseased or degenerated, serious pathology and symptoms occur. If left uncorrected, heart failure and death will eventually ensue. The Ross procedure is unlike other valve repair or replacement operations. The pulmonary autotransplant operation most closely resembles repair operations that have dominated the surgical treatment of mitral disease in the last 15 years. Although the Ross procedure does not attempt to repair the native aortic valve, the primary advantage of the autotransplant procedure is just the same...reconstruction entirely with living host tissue. No artificial or man-made material is used.

Replacement of the aortic valve with a man-made prosthesis can be accomplished with a tremendous margin of safety. The operative mortality rate for simple mechanical valve replacement is 2% in patients less than 70 years of age. For patients above the 7th decade of life, the operative mortality rate is still a respectable 5%. With a simple aortic valve replacement, blood transfusion requirements are very low, and most patients are able to leave the hospital within 5 days. In addition, the long term survival is 60% at 15 years, with most deaths related to non-cardiac causes.

Despite many advances in both clot-resistant materials and valve design, there is still a significant risk of clotting or strokes in patient receiving modern mechanical valve implants. Current recommendation is for all mechanical valve recipients to receive life-long anticoagulation with Coumadin® . Although Coumadin® is currently the best drug for reducing clotting on artificial heart valves, it is by no means perfect. In large groups of mechanical heart valve patients studied over time, the risk of a clot formation on the valve is between 2 and 4% per patient-year even when Coumadin® is administered. In addition, the use of Coumadin® is associated with excessive bleeding in some patients. The long-term risk of Coumadin® -related bleeding is about the same, in the range of 2 to 4% per patient-year. Thus the patient implanted with a mechanical aortic valve continues to run some long term risks of either a stroke or major bleeding episode in the range of 4 to 8% (combined) per year. Despite several generations of new valve materials and designs, the risk of these adverse events over time has not been reduced significantly.

Alternatives to the mechanical valve are primarily animal tissue (or Xenograft valves which can be used without Coumadin® . By implanting a valve made of animal tissue, the need for blood thinners is reduced or eliminated. The porcine (pig) aortic valve is the most widely used for replacement of disease human heart valves. The porcine valve is tanned with a stringent chemical called glutaraldehyde, an agent similar to, but stronger than, formaldehyde. This processing toughens the leaflets and cross-links many of the proteins. In doing so, the valve is also rendered less likely to be rejected by the hosts immunologic defenses. However, the tanned leaflets are no longer living, viable tissue.

One of the major drawbacks for xenograft valves is limited durability. Tissue valve leaflets tend to wear out, weaken, and often develop tears or perforations over time. Some of these valves will stiffen and calcify. Although these degenerative processes happen slowly and with plenty of warning, any valve showing this type of deterioration will need to be changed again. Xenograft (animal tissue) valves usually begin to degenerate within 8 to 10 years after implantation. Within 15 years, over 30% of tissue valve recipients will need another valve replacement operation. In patients less than 60 years of age, the degenerative process occurs more quickly. In patients less than 40 years of age, animal tissues valves may degenerate within 5 years of implantation. It was once hoped that the use of an animal tissue valve would prevent the need for Coumadin® anticoagulation in children, but the premature degeneration of xenograft valves in the younger (pediatric) age range proved to be a major disappointment.

Thus the major disadvantage of biological (or tissue ) heart valve substitutes is the need for a second operation in the near future. Most studies now indicate that a patient surviving more than 10 years after valve replacement surgery is better off with a mechanical replacement than a porcine or bovine tissue valve, even despite the added problems of chronic Coumadin®.

Another biologic substitute proposed by some surgeons is the human cadaver aortic valve, also known as the aortic homograft. The development of this type of valve replacement was also pioneered by Mr. Ross simultaneously with Brian Barrett-Boyces of New Zealand. This operation replaces the diseased valve with a naturally occurring normal aortic valve from another person, procured after death. It took many years to perfect the surgical implant techniques, but eventually the homograft aortic valve replacement could be performed with acceptable operative mortality and morbidity. At first, the homograft procedure appeared to answer most of the concerns presented by mechanical and/or xenograft valve surgeries. However, after several decades of patient follow-up, concerns about homograft valve durability arose. The mean survival of these valves appeared steady for the first 10 or 12 years, but then leakage typically began to develop slowly. Over time, the wall of the homograft aorta surrounding the valve became severely calcified, creating increased surgical difficulty at the time of subsequent replacement. Rejection of the aortic tissue may play a role in this form of degeneration. Research has indicated that homograft dysfunction is much more common, and more severe, in the younger age ranges. In fact, the one group of patients most likely to benefit from the long term cure of aortic valve disease, the pediatric population, is once again the most vulnerable to early calcification and degeneration in aortic homografts. Thus the ideal replacement for the diseased aortic valve, particularly in the younger patient, was still not accomplished.

After several decades of patient follow-up became available for the Ross procedure, a different set of data was discovered. The pulmonary autograft transplanted to the aortic position was not calcifying, leaking, or showing signs of degeneration. The freedom from reoperation for recipients of a pulmonary homograft was 83% at 18 years [Ross 1996]. The encouraging results from the very earliest pulmonary autotransplants appeared to show that a completely native reconstruction of the aortic valve using the patients own pulmonary valve provided the long lasting results sought. At 20 years, only 15% of patients required another valve operation, usually replacement of the homograft reconstruction of the right ventricle [Ross 1996]. Patient survival at 18 years is an impressive 70%, making this operation superior to all other forms of aortic valve or root reconstruction.

Advantages of the Pulmonary Autotransplant procedure

Transfering the pulmonary valve into the aortic position has many distinct advantages for the patient. First, the pulmonary valve is nearly always the perfect size. It is made of native, living tissue and thus will not be rejected by the recipient. In children, the Ross autotransplant has the unique advantage that the new aortic reconstruction will grow as the child grows. No other valve replacement operation can provide this important advantage in the treatment of congenital problems of the aortic valve. The freedom from long term anticoagulation is not to be underestimated, especially in children and teenagers where chronic anticoagulation is hard to maintain. Freedom from strokes, clots, secondary infection, and valve leaflet degeneration requiring further surgery are major advantages for this operation.

In addition, since the pulmonary valve is always the "right size", the performance of the valve is ideal. In long term followup studies, the autotransplanted valve is never obstructive or stenotic. Some mechanical or tissue valves are not large enough for the recipient, resulting in stenosis. This has not been a problem with the Ross procedure.

The pulmonary valve provides the appropriately sized, naturally designed replacement for the diseased aortic valve. The hemodynamic performance of the autotransplant is ideal, with no measurable gradients across the aortic outflow tract after completion of the repair.

Autografts are always sterile, non-antigenic, and are created with the perfect design. They are functionally, structurally, and histologically nearly identical to the aortic valve. The size is nearly identical, with 95% of patients yielding a pulmonary valve within 3 mm of the diameter of the patients aortic annulus. Use of the root replacement technique provides complete transposition of the entire sinotubular mechanism, preserving the size and orientation of the entire valve closure mechanism, reducing complications, and making the surgical techniques easier and more reproducible.

A women of child bearing age with aortic valve disease represents a special challenge. The age range of child bearing is roughly from the onset of menstruation (about 12 years of age) to menopause (age 40 - 45 years old). Any valve substitute chosen for a female patient within those age ranges must be durable enough to provide many decades of uninterrupted performance. At the same time, mechanical valves require Coumadin® to prevent thromboembolism (clot formation leading to stroke or other tragic consequences). Coumadin® taken by the pregnant mother can cause birth defects in the fetus. Thus any heart valve replacement in a woman of child bearing years must permit her to exist safely without the burden of anticoagulation. Unfortunately, porcine or bovine tissue valves, and human homograft valves do not last long enough to be an effectively curative operation in a young woman. All of these surgical and clinical issues are avoided by using the Ross procedure on women of child bearing age.

In summary, there are many unique advantages to consider when recommending the Ross operation for patients with aortic valve disease, including:

• Virtual absence of anticoagulation
• Virtual absence of late thromboembolism (clots, strokes)
• Absence transvalvar gradients (< 30 mmHg in every case)
• Highly resistant to endocarditis.
• Superior long term durability in the aortic position.
• Low reoperation rate (15% at 20 years).
• Documented growth after Ross operation when performed in children.
• No sudden valve failures or sudden death from aortic valve malfunction.
• The only aortic valve replacement made from living, viable tissue.
• No possibility of rejection by the recipient (of the pulmonary autotransplant)
• Low failure rate in the pulmonary homograft replacement.
• Replacement of a failed pulmonary homograft is much lower risk than a redo aortic valve.
• Improved safety (and long term durability) in women of child bearing age.

Drawbacks and/or disadvantages

No matter how much improvement has been made in the surgical techniques for performing the pulmonary autotransplant procedure, there are still some drawbacks. The one aspect that remains unsolved is the magnitude of the surgical procedure. Some critics are concerned that transferring of the pulmonary valve converts a patient with only aortic valve problems to a patient with 2 heart valves now in jeopardy. The potential for premature degeneration of the pulmonary substitute has also been voiced. Fortunately, the long term results now available tend to refute both of these concerns.

Analysis of the data, however, does reveal that premature failure of the homograft is much more common when human aortic tissue was used in the right side reconstruction, as opposed to human pulmonary tissue. There was only a 74% freedom from reoperation at 5 years when aortic homografts were used for the right ventricular reconstruction. However, there is a 94% freedom from reoperation at 5 years (and 83% at 20 years) when a pulmonary homograft is implanted into the right ventricular outflow tract. The reasons for this dramatic difference are not known. However, the pulmonic valve and supporting structures appears to be more tolerant, and possible less antigenic.

In summary, the major disadvantages of this operation for the surgical treatment of aortic valve disease are outlined below.

• Lengthy operative times (over 2 and 1/2 hours to complete the repair)
• Technically more demanding on the surgeons skills.
• Cannot be used in every patient (such as those with Marfans syndrome or other connective tissue disorders)
• Cannot be effectively combined with other valve operations or coronary bypass (due to the lengthy operative times required).
• Limitations in availability of appropriate sized pulmonary homografts for replacing the donor site (particularly in children).
• Theoretically converts a single valve patient to a double valve patient.

1. Ross, D. Personal communication. Controversies in Homograft and Autograft Surgery. The Ross Procedure Symposium. May 8-11, 1996. Indianapolis, Indiana.

2. Joyce F, Tingleff J, Pettersson G. Expanding Indications for the Ross Operation. The Journal of Heart Valve Disease 4(4):352-363, July 1995.

Ross Procedure Sections: Introduction | History | Anatomy | Pros & Cons | Patient Selection | Technique | Results | Pediatric Ross

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