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Mar 19, 2015

Automatic method can improve heart valve surgery


 

In the last decade, a new procedure named Transcatheter Aortic Valve Implantation (TAVI), has emerged as a solution for patients suffering from aortic stenosis. One of the challenges in the TAVI procedure is the sizing of the valve prosthesis, as the size of the aortic valve varies greatly between patients.

Researchers at CCI have created a 3D method for sizing the aortic valve automatically. The method has so far been evaluated on 16 patients with aortic stenosis, and showed good agreement with manual observers. These findings were presented at the European Society of Cardiology Congress (poster P3459) in Barcelona last year, and have been published in BMC Medical Imaging. GE Vingmed Ultrasound and CCI are working on commercializing the method, which will help bring it in to clinical practice.

This new method has also been noted by www.unikard.org
Picture of PhD student Jørn Bersvendsen.
Posted by: Anonymous

Text by Jørn Bersvendsen.

Aortic stenosis, a condition where the blood flow through the aortic valve is restricted, is the most common valvular heart disease in the western world. In the USA alone, approximately 300 000 people suffer from this disease which is typically caused by progressive calcification as you grow old. For patients with symptomatic and severe aortic stenosis, the prognosis without treatment is terrible, and as little as half of the patients survive past two years of symptom onset without intervention.

The standard care for these patients is surgical aortic valve replacement, where a valve prosthesis is implanted by open heart surgery. However, some patients are simply so ill that the risk involved with such a large procedure is unacceptably high.

In the last decade, a new procedure, named Transcatheter Aortic Valve Implantation (TAVI), has emerged as a solution for these high-risk patients. In this procedure, the valve prosthesis is implanted by a catheter inserted in the upper leg, thus avoiding open heart surgery. To date, about 75 000 such procedures have been performed worldwide, and is widely considered a success of modern minimal invasive surgery.

One of the challenges in the TAVI procedure is the sizing of the valve prosthesis, as the size of the aortic valve varies greatly between patients. If you insert a valve that is too small, it will leak. Insert a valve that is too large and you risk rupturing the heart tissue. Precise sizing is therefore crucial, and because the procedure is not performed with an open chest, it has to be done prior to surgery based on medical imaging.

To help with this problem, researchers at the CCI have created a method for sizing the aortic valve automatically. Regular 2D ultrasound is not well suited for performing this sizing, as it fails to appreciate the complex 3D structure of the aortic valve and its surrounding region. The automatic method therefore operates on 3D ultrasound for a more accurate measurement. In 3D ultrasound the amount of information is increased significantly compared to its 2D counterpart, which can make it hard to assess manually. However, the proposed algorithm is able to utilize all the information in the ultrasound image sequence to create a personalized geometrical representation of the patient’s anatomy in a matter of seconds.

The method has so far been evaluated on 16 patients with aortic stenosis, and showed good agreement with manual observers. These findings were presented at the European Society of Cardiology Congress (poster P3459) in Barcelona last year, and have been published in BMC Medical Imaging. GE Vingmed Ultrasound and CCI are working on commercializing the method, which will help bring it in to clinical practice.

Automatic measurement of aortic annulus diameter in 3-dimensional transoesophageal echocardiography.
Bersvendsen J, Beitnes JO, Urheim S, Aakhus S, Samset E. 
BMC Med Imaging. 2014 Sep 8;14(1):31
doi: 10.1186/1471-2342-14-31
PMID: 25200865

Read more about aortic stenosis:
Asymptomatic Aortic Stenosis in the Elderly - A Clinical Review
Valve Disease - Timing of aortic valve surgery

Center for Cardiological Innovation