(June 17th, 2026) Webinar: Doppler-Derived Hemodynamics to Assess Cardiac Remodeling in Mice with Transverse Aortic Constriction
This webinar addressed topics ranging from validating surgical outcomes to tracking disease advancement, encompassing typical carotid and stenotic jet velocities, evaluations of cardiac function, coronary flow reserve, and cerebral perfusion through ophthalmic artery flow. Whether attendees were new to TAC or seeking to enhance their monitoring methods, the session provided practical guidance for achieving more consistent and thorough cardiovascular outcomes.
Key Points:
- Overview of TAC, Doppler flow velocity measurements, and physiological monitoring during surgery and imaging.
- Demonstration of standard measurements pre- & post-TAC and importance of initial stratification via severity of stenosis to classify in animals for proper comparison.
- Ways to monitor surgical success and outcomes
- Discussion of Doppler applications and reviewing results from studies.
Webinar Overview
Accurate, non-invasive physiological monitoring is key to reproducible animal research. Introduced over three decades ago, the cardiac pressure overload mouse model created by transverse aortic constriction (TAC) has undergone several procedural modifications. Regardless of the type of TAC procedure, it is crucial to confirm surgical success early, noninvasively monitor the outcomes, and to stratify the animals based on severity of stenosis. Measurements typically include Doppler flow velocity, along with structural imaging by ultrasound or MRI. This presentation focused mainly on the Doppler measurements that included the standard left and right carotid flow velocities, stenotic jet velocity, and aortic and mitral velocities to study cardiac function. Furthermore, coronary flow reserve which defines the heart’s functional capacity to increase blood flow when oxygen demand rises and the potential to measure cerebral perfusion via left and right ophthalmic artery flow velocities during TAC were discussed.
Topics Covered
- Cardiac pressure overload mouse model of transverse aortic constriction (TAC)
- Variability in the TAC surgical outcomes
- Ways to monitor surgical success and outcomes
- Importance of stratification of animals
Understanding Transverse Aortic Constriction (TAC)
Transverse Aortic Constriction (TAC) is a challenging surgical procedure developed to study the cellular and molecular pathways of left ventricular cardiac hypertrophy and heart failure. Since its introduction over three decades ago, TAC has undergone several modifications. Key advancements include the shift from highly invasive open-chest surgeries to minimally invasive closed-chest procedures; this transition minimizes inflammatory responses and the complex physiological compensations required to maintain stability at both the systemic and cellular levels.
Evolution of TAC Methodologies
Originally, TAC utilized silk or nylon sutures, which often caused variability in stenosis size or suture slippage. While O-rings with fixed inner diameters were introduced to ensure consistency, they can create artifacts during echocardiographic imaging. Furthermore, imprecise O-ring placement can lead to inconsistent pressure gradients, damage to surrounding structures, or unintended lung congestion caused by pressure on the pulmonary artery. Other specialized methods include “de-banding” (removing the constriction) to study reverse remodeling.
Disease Progression in TAC Models
Studies: Mouse TAC models simulate human pressure-overload conditions, such as aortic stenosis or hypertension. By surgically narrowing the aortic arch between the brachiocephalic trunk and the left carotid artery, chronic pressure overload is induced. The heart follows a predictable timeline – a) 1-2 weeks of early compensatory phase when the heart adapts via concentric hypertrophy (wall thickening) to maintain function. This often results in a temporary preservation or enhancement of cardiac contractility. b) 4-8 weeks of decompensated phase when the heart progresses into left ventricular (LV) dilation as it can no longer compensate for the pressure.
Advantages of Doppler Monitoring
A big advantage of Doppler measurements is that they can be made immediately after ligation of the aorta before closing the skin to confirm the success of TAC. Additionally, Doppler measurements can be made at several time points during studies lasting 8-12 weeks providing multiple snapshots of the disease progression. This allows researchers to monitor gradual changes and to evaluate the precise timing of drug therapies or de-banding effects.
Key Takeaways
Regardless of the specific TAC technique used, it is vital to confirm surgical success early and noninvasively monitor outcomes to stratify animals by stenosis severity. While measurements include structural imaging via ultrasound or MRI, this presentation focused primarily on Doppler measurements. These included standard left and right carotid flow velocities, stenotic jet velocity, and aortic and mitral velocities. Additionally, the presentation discussed the status of coronary flow reserve – which defines the heart’s capacity to increase blood flow under oxygen demand – and the distribution of ophthalmic artery blood flow as a potential index of cerebral perfusion during TAC.
Watch Our Recorded Virtual Workshop & Presentation
About the Speaker
Anilkumar Reddy, PhD, is a Principal Scientist at Indus Instruments, where he leads preclinical product development and the exploration of novel biomedical applications. During his extensive career at Baylor College of Medicine, he specialized in evaluating cardiac and vascular mechanics in rodent models to advance methods for the early detection of cardiovascular diseases that included atherosclerosis, aortic stenosis, and myocardial infarction, hypertension, and others. Dr. Reddy has championed the use of non-invasive methods, such as pulsed Doppler flow velocity and ultrasound imaging, to phenotype animals and monitor cardiovascular adaptations during disease progression. At Indus, he contributes to the design, development, and testing of custom sensors and instrumentation used to assess physiological and cardiovascular function in small animals.