TAVR Measurements – 3D and Quantitative Imaging Laboratory

Introduction

Transcatheter Aortic Valve Replacement (TAVR) is a minimally invasive procedure used to replace a damaged aortic valve, particularly in patients who are older or considered high-risk for open-heart surgery. Unlike traditional surgery, TAVR is performed by inserting a new valve through a catheter, usually via a small incision in the leg or chest. This eliminates the need to fully open the chest or stop the heart, making the procedure less risky and allowing for a quicker recovery. The aortic valve, which regulates blood flow from the heart into the aorta, can become narrowed due to a condition called aortic stenosis, which restricts blood flow and forces the heart to work harder.

Aortic stenosis is typically caused by calcium buildup on the valve, especially in older adults, and can lead to severe symptoms like shortness of breath, chest pain, and fatigue. If untreated, it can result in heart failure or death. Traditionally, this condition was treated through open-heart surgery, but TAVR offers a safer and faster alternative for many patients. By replacing the valve through a catheter, TAVR significantly reduces recovery time and provides a life-saving option to those who may not be suitable candidates for more invasive open-heart surgery.

Read more in our introductory TAVR article here.

Measurements

To ensure a successful TAVR procedure, standardized measurements of relevant cardiac structures are required, as the replacement valve needs to fit perfectly within the aortic annulus to function properly and avoid complications. These measurements are typically taken using a CT angiogram, an imaging scan that provides comprehensive data as the heart moves through all phases of the cardiac cycle. IV contrast is used in conjunction with the CT angiogram, allowing doctors to assess the size, shape, and function of the aortic valve and surrounding structures.

Measurements are captured at two crucial points in the heart’s pumping cycle: during systole and diastole. Systole occurs when the heart contracts to pump blood out, and this is when the aortic annulus (the ring-like structure where the valve sits) is at its largest. The systolic measurement is particularly important because it provides the maximum annular size, helping to ensure that the replacement valve is appropriately sized. In addition to measuring the annulus, the height of the coronary arteries from the annulus is also measured. These arteries supply blood to the heart muscle, so their proximity to the aortic valve means that careful measurements are needed to ensure the new valve doesn’t obstruct them, which could lead to severe complications.

Figure A (Right): Measurements created for TAVR used guide the selection of the appropriate valve and ensure it can be navigated through the patient’s anatomy and successfully deployed at the valve site.

Providing Measurements

Once TAVR measurements are taken, they undergo a Quality Control (QC) process to ensure accuracy, then are stored in PACS (Picture Archiving and Communication System) and hosted on our custom web portal. A summary of key measurements is also emailed to the surgical team along with snapshots from the web portal. The emailed summary allows the cardiovascular team to easily reference the patient’s measurements and images throughout the treatment planning process. In the operating room, the custom web portal allows surgeons to quickly verify measurements and angles, ensuring the procedure is performed smoothly and with precision.

Selecting a Valve

While our team is responsible for gathering the measurements, we don’t directly choose the valve to be implanted. Our main role is to provide accurate data on the patient’s heart and aortic valve, which is important for determining the correct valve size and type. The measurements are reviewed in a weekly TAVR planning meeting by a team of surgeons, radiologists, and other specialists. These experts use the data to decide which valve is most appropriate for the patient, taking into account factors like valve size, shape, and condition. We also assist during these meetings by providing on–demand imaging requests. These images allow the team to visualize any anatomy currently being discussed, which can include how the replacement valve will be positioned and how it interacts with surrounding structures.

Figure B (Right): A photo from the weekly TAVR meeting, where surgeons, doctors, specialists, and technologists gather to assess patients for the upcoming week.

C-Arm Alignment

The C-arm is an X-ray device that provides live images during the procedure, allowing the surgical team to see the heart and position the replacement valve accurately in real-time. To align the C-arm correctly, we need to calculate the annular plane of patient’s aortic valve, which is the ring-like structure at the base of the aortic valve where the three valve cusps (non-coronary, right coronary, and left coronary) meet.

The goal is to allow surgeons to quickly adjust the C-arm so that the X-ray beams are aligned with the annular plane. This allows the surgeon to see all three cusps in a single, aligned view without having to expose the patient to extra radiation while trying to align manually. This alignment is also important because it ensures that the replacement valve is positioned correctly, reducing the risk of complications like valve leakage, blockage of the coronary arteries, or poor valve function. The exact angles for each patient are input into a formula in our custom web portal, which generates a table of values for the procedure.

Previously, we would assist the surgical team in calculating and adjusting these angles during the procedure, but since the COVID-19 pandemic, we have redesigned our web portal to allow this process to be managed independently by the surgical team without our on-site involvement.

Figure C (Above): These measurements are entered into a formula that calculates the optimal C-arm angles, providing valuable radiation-reducing guidance during the procedure.

Figure D (Above): The resulting C-arm calculations displayed in our custom web portal.

Introduction

Measurements

Providing Measurements

Selecting a Valve

C-Arm Alignment

3DQ Lab – Grant Building

3DQ Lab – Clark Building

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