Universal Standards Established for Vascular Ultrasound Imaging Validation

A collaboration has been undertaken to prepare industry standards for the development and evaluation of diagnostic tools that examine how the heart interacts with larger arteries. This partnership is one of the first of its kind, and is an excellent example of an industry manufacturer working with clinicians to establish universal clinical standards--and validation techniques--that will help to improve the effectiveness and safety of diagnostic systems.

Hitachi Aloka Medical (Tokyo, Japan) is collaborating with Prof. Alan Fraser, a clinical professor at the Institute of Molecular & Experimental Medicine at Cardiff University School of Medicine (Cardiff, Wales, UK) in the project. Prof. Fraser stated, “Ultrasound machines from different manufacturers, and even different models from the same manufacturer, often give different values for the same measurements. Establishing industry standards and normal values for each manufacturer will help clinicians enormously in establishing quickly what is and is not a diagnostically significant result in an individual patient. It surprises me that more manufacturers have not adopted a progressive and open approach to validating new diagnostic tools, like Hitachi Aloka Medical.”

Cardiologists from 13 centers in Europe have collaborated in the study, coordinated from Cardiff, to pool results from eTRACKING of carotid arteries using Hitachi Aloka Medical vascular transducers in more than 2,000 normal subjects. Increased arterial stiffness--especially in arteries located close to the heart, such as the carotid--causes increased pressure and load to be placed on the heart. This process is understood to occur because reduced arterial compliance (increased arterial stiffness)--which is measured by eTRACKING--modifies the timing of wave reflections.

For example, during ventricular ejection a forward pressure wave is generated, which is then reflected back from the arterial tree. In patients with increased arterial stiffness, the reflected wave travels more quickly back to the heart, meaning that when it arrives the aortic valve has not had a chance to close (i.e., it arrives during left ventricular [LV] ejection), so the central systolic blood pressure and LV afterload are both increased. This causes the heart muscle to increase in size (left ventricular hypertrophy). Over time, the heart’s increased muscle mass will also cause slow relaxation of the heart muscle and difficulty in filling.

The interactions between the heart and reflected waves have been studied using the special methods developed by Hitachi Aloka Medical, for estimating the local direction and amplitude of waves in an artery--wave intensity--via simultaneous recordings of diameter (with pressure) and velocity. The results have given clinicians new insights into how arteries and ventricles interact, especially in the presence of arterial disease.

Together, these two new diagnostic tools--eTRACKING and wave intensity--provide effective methods for determining the effects of drugs on altering the interactions between the heart and arteries. It is now possible to discriminate between the peripheral and central effects of drugs, which will help clinicians to choose treatments for patients that are most likely to reduce the risk of heart failure. Drugs that modify the timing as well as the amplitude of reflected waves may be most effective in reducing stress on the heart.

Prof. Fraser concluded, “We have already successfully tested the Hitachi Aloka diagnostic tools for Wave Intensity and eTRACKING--contributing to breakthroughs in our concepts of the mechanisms of cardiovascular disease and ventricular-arterial coupling.”

Hitachi Aloka Medical, Ltd. is a company established on April 1, 2011 by an incorporation between the diagnostic ultrasound business of Hitachi Medical Corp. and Aloka Co., Ltd.

Related Links:
Hitachi Aloka Medical
Cardiff University School of Medicine