Stylized fetal heart with Doppler waveforms, representing precision in fetal cardiac measurement.

Decoding Fetal Heart Health: A New Tool for Accurate AV Interval Measurement

Mira Elwood in Health & Wellness December 2025 • 5 min read.

"Discover how a novel image scoring method is enhancing the precision of fetal atrioventricular (AV) interval measurements, offering new hope for early detection and management of congenital heart block."

Congenital heart block, a condition affecting approximately 1 in 15,000 live births, presents a significant challenge in prenatal care. Often diagnosed between 20 and 24 weeks of gestation, complete atrioventricular block (AVB) can lead to mortality rates as high as 16-20% in fetuses of mothers with anti-SSA/SSB antibodies. The ability to accurately assess and monitor fetal heart function is, therefore, critical.

A key measurement in assessing fetal heart health is the atrioventricular (AV) interval, which reflects the electrical PR interval. This measurement, traditionally taken using pulsed Doppler techniques in a five-chamber view of the fetal heart, can be challenging to perform and interpret consistently. The accuracy of this measurement is vital for early detection of potential heart issues and for guiding appropriate interventions.

Recognizing the need for improved precision and reliability, researchers have developed a new image scoring method designed to enhance the quality and consistency of AV interval measurements. This method aims to provide a standardized approach for sonographers, ultimately improving diagnostic accuracy and patient outcomes. Let’s explore how this innovative technique is making a difference in fetal cardiac care.

The Innovative Image Scoring Method: Enhancing AV Interval Measurement

Stylized fetal heart with Doppler waveforms, representing precision in fetal cardiac measurement.

The image scoring method is structured around a detailed grid encompassing both anatomical and Doppler settings. This grid is composed of five criteria focusing on anatomical conditions and five on Doppler settings. The goal is to standardize the image acquisition process, ensuring that sonographers capture the most accurate and interpretable images possible.

To evaluate the effectiveness of this new scoring method, a prospective study was conducted involving sonographers trained in antenatal diagnosis. The sonographers were tasked with measuring AV intervals in standard screening ultrasounds, both before and after being introduced to the image scoring method. The images were then scored by two blinded reviewers to assess image quality and consistency.

Anatomical Structure Identification: Ensuring the five-chamber view is correctly oriented, with clear visibility of key structures like the interventricular septum and mitral valve.
Image Zoom: Maintaining a consistent zoom level to occupy three-quarters of the image, providing sufficient detail for accurate assessment.
Pulsed Doppler Gate Position: Precisely positioning the Doppler gate in the left ventricle at the junction of the anterior mitral valve leaflet and left ventricular outflow tract.
Angle Correction: Keeping the angle between blood flow and baseline below 25 degrees to minimize errors in velocity measurement.
Spectral Analysis: Correctly identifying the onsets of atrial and ventricular contraction on spectral analysis to accurately measure the AV interval.
Velocity Scale: Setting the velocity scale to capture four to six cycles per image for optimal visualization of waveforms.
Pulse Repetition Frequency: Configuring the pulse repetition frequency to at least 10 cm/s above systolic wave velocity to avoid aliasing.
Filter Settings: Properly configuring filters to eliminate artifacts from pulsating vessel walls without losing essential waveform information.

Each of these criteria is assigned a point value, contributing to a total score out of ten. An image is considered valid if it achieves a score of seven or higher, ensuring that only high-quality images are used for AV interval measurement. This scoring system provides a clear, objective benchmark for image quality, reducing subjective variability among sonographers.

The Future of Fetal Cardiac Care

This innovative image scoring method represents a significant step forward in the field of fetal cardiac care. By standardizing the process of AV interval measurement and improving image quality, this technique has the potential to enhance diagnostic accuracy, reduce variability among sonographers, and ultimately improve outcomes for fetuses at risk of congenital heart block. Further research and widespread adoption of this method could transform the early detection and management of fetal cardiac conditions.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.jogoh.2018.10.022, Alternate LINK

Title: Pulsed Doppler Fetal Atrioventricular Interval Measurement: Assessment Of A New Image Scoring Method

Subject: Obstetrics and Gynecology

Journal: Journal of Gynecology Obstetrics and Human Reproduction

Publisher: Elsevier BV

Authors: Adélie Michau, Laurence Gitz, Francine Proulx, Marion Besse, Sophie Tezenas Du Montcel, Brice Leclère, Marc Dommergues, Alexandra Benachi

Published: 2019-02-01

Everything You Need To Know

What is the atrioventricular (AV) interval and why is it important in assessing fetal heart health?

The atrioventricular (AV) interval is a key measurement used to assess fetal heart health. It reflects the electrical PR interval and is traditionally measured using pulsed Doppler techniques. Accurate measurement of the AV interval is vital for the early detection of potential heart issues, such as congenital heart block, and for guiding appropriate interventions. The AV interval helps healthcare providers understand the timing and coordination of electrical signals in the fetal heart, which is crucial for proper heart function.

What is congenital heart block, and why is its early detection so important?

Congenital heart block is a condition where the electrical signals that control the heart's rhythm are disrupted, leading to a slower heart rate. Complete atrioventricular block (AVB) can be particularly severe, with high mortality rates in fetuses, especially those whose mothers have anti-SSA/SSB antibodies. Early and accurate diagnosis through measurements like the AV interval is crucial for timely intervention and management, potentially improving outcomes for affected fetuses.

How does the new image scoring method improve the accuracy of fetal AV interval measurements?

The innovative image scoring method enhances the precision of fetal atrioventricular (AV) interval measurements by providing a standardized approach for sonographers. It is structured around a detailed grid encompassing both anatomical and Doppler settings. This method assigns points based on criteria such as proper anatomical structure identification, image zoom, pulsed Doppler gate position, angle correction, and spectral analysis. By ensuring high-quality images are used for measurement, the scoring method improves diagnostic accuracy and reduces variability among sonographers.

What are the anatomical criteria used in the image scoring method, and why are they important?

The anatomical criteria within the image scoring method focus on ensuring that key structures of the fetal heart are clearly visible and correctly oriented during ultrasound. These criteria include proper identification of structures like the interventricular septum and mitral valve. Fulfilling these criteria ensures that the sonographer is obtaining images that provide sufficient detail for accurate AV interval measurement. Proper anatomical visualization is essential for correctly interpreting the Doppler signals and assessing heart function.

What are the Doppler settings criteria used in the image scoring method and why are they important?

The Doppler settings criteria within the image scoring method are crucial for capturing accurate and interpretable ultrasound waveforms. These criteria include setting the correct velocity scale, pulse repetition frequency, and filter settings. Properly configuring these parameters ensures that the waveforms representing atrial and ventricular contractions are clearly visualized, free from artifacts, and accurately measured. These settings minimize errors in velocity measurement and provide optimal visualization of waveforms, which are critical for precise AV interval assessment.