New Aortic Root Enlargement Technique May Preserve Future TAVI Options After SAVR
When replacing the aortic valve, a small aortic root can limit the size of the prosthetic valve that can be implanted. If the new valve is too small in relation to the patient’s body, the heart must continue to work against increased resistance – a so-called patient-prosthesis mismatch, which is associated with poorer clinical outcomes. A new surgical technique has now been developed at the Department of Cardiac and Thoracic Aortic Surgery at the Medical University of Vienna and University Hospital Vienna, which allows the aortic root to be dilated in a relatively simple and minimally invasive manner. This enables significantly larger prosthetic valves to be implanted, improves blood flow and, at the same time, creates better conditions for future treatment options. The new method and initial clinical findings have been published in the cardiac surgery journal JTCVS Techniques.
The replacement of the diseased aortic valve is regarded as one of the success stories of cardiac surgery. It began in 1960 with the first valve implantations. Over the decades since then, many different mechanical and biological prosthetic valves have been developed and implanted. One problem has remained unchanged since the inception of surgical aortic valve replacement: the annulus required to anchor the prosthetic valve can restrict effective blood flow from the left ventricle into the aorta – particularly in patients with a small aortic root.
Today, this issue is becoming even more significant because the choice of the initial prosthetic valve must take into account not only the current operation but also the patient’s entire lifelong treatment strategy. In the spirit of modern ‘lifetime management’, consideration should therefore be given as early as the first procedure to which options remain open for subsequent interventions – such as transcatheter aortic valve implantation (TAVI) within an existing surgical prosthesis. Sizing the first prosthetic valve as generously as possible can create the crucial conditions for this. A decisive step has now been taken at the Department of Cardiac and Thoracic Aortic Surgery at the Medical University of Vienna and the University Hospital Vienna (AKH): a method has been developed which is comparatively simple from a surgical technical perspective, alters the established procedure only slightly, and at the same time takes the natural anatomy of the aortic root into account.
The Problem: The Suture Ring Takes Up Space
The aortic valve is the valve between the left ventricle and the aorta. If it needs to be replaced, the prosthesis is sutured into the so-called aortic annulus using a suture ring. This suture ring requires space – which is why, with established valve prostheses, the opening of the prosthesis is often smaller than the natural opening of the valve. If the aortic annulus is naturally small, only a small prosthesis can be implanted. If the prosthesis is too small in relation to the patient’s body, the heart has to pump against increased resistance. This is referred to as a patient-prosthesis mismatch, which is associated with poorer outcomes. Larger prostheses also offer better prospects should further treatment with a catheter within the existing valve become necessary years later.
The Alfred Kocher Technique
Alfred Kocher, Head of the Heart Valve Team at the Department of Cardiac and Thoracic Aortic Surgery at the Medical University of Vienna and University Hospital Vienna, first described the ‘Alfred Kocher technique’ – named after him – for enlarging the aortic root in June 2025 and published the procedure in the cardiac surgery journal JTCVS Techniques. Since then, the method has been used successfully at MedUni Vienna and is now also being applied at centres across Europe and the USA.
The operation begins in the same way as a conventional aortic valve replacement. Only after the aortic annulus has been measured is a decision made as to whether enlargement is necessary. To this end, the aortic root is enlarged using a T-shaped incision and reconstructed with a specially shaped patch. The coronary arteries remain unaffected, and the natural shape of the aortic root is largely preserved. This allows prosthetic valves that are at least two sizes larger to be implanted.
“The key advantage of our technique is that we initially proceed as with conventional aortic valve replacement and only need to decide whether an enlargement is necessary after taking the measurements. With a comparatively simple additional surgical step, we can implant significantly larger prosthetic valves without affecting the coronary arteries. It is particularly important that the technique can be performed not only via conventional access but also using minimally invasive and even endoscopic methods,” says Alfred Kocher.
The Department of Cardiac and Thoracic Aortic Surgery, headed by Daniel Zimpfer, is thus playing a leading international role in the further development of surgical aortic valve replacement. The aim is to overcome existing limitations of the operation whilst creating less invasive access routes and optimal conditions for the long-term ‘lifetime management’ of patients.
Aortic Valve Replacement Is Being Completely Overhauled
The new technique is part of a wider initiative: within the department, surgical aortic valve replacement is being completely overhauled and standardised. First, the natural dimensions of the aortic annulus are measured using a universally applicable measuring head. The appropriate valve is then selected. If the aortic annulus is too small, the aortic root is dilated using the Alfred Kocher technique. As part of this development, several invention disclosures have been submitted for patent in collaboration with the Department of Technology Transfer at MedUni Vienna.
The standardised procedure is based on a simple principle: today, a prosthetic valve is designed to last a lifetime, not just for a single operation: “In aortic valve surgery, we must now take into account not only the immediate operation but also our patients’ entire subsequent treatment pathway. A sufficiently large prosthetic valve is a key prerequisite for this. The new technique expands our ability to create optimal conditions for long-term care right from the first procedure,” says Daniel Zimpfer, Head of the Department of Cardiac and Thoracic Aortic Surgery.
Reference
Kocher AA, Werner P, Osorio-Jaramillo E, Kahrovic A, Zimpfer D, Ehrlich M, Laengle S. A. Kocher technique as default approach to aortic root enlargement. JTCVS Tech. 2026 Mar 2;37:102296. doi: 10.1016/j.xjtc.2026.102296
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