# Determining strength and temporal stability of rotational and focal sources during human atrial fibrillation

> **NIH NIH R21** · UNIVERSITY OF CALIFORNIA, SAN DIEGO · 2020 · $118,125

## Abstract

Project Summary
Atrial Fibrillation (AF) is the most common cardiac arrhythmia during which the normal, organized rhythm is
disrupted and replaced by irregular wave propagation which compromises the primary mechanical function
of the heart. It is a serious health concern that, if left untreated, can lead to increased morbidity and even
mortality. With the aging of the population, it is a growing problem that affects millions of Americans and
represents a considerable economic burden. Unfortunately, the existing therapies have limited success,
mostly because the mechanisms that initiate and maintain AF remain poorly understood.
Multi-electrode arrays, which can record unipolar electrograms at many discrete sites, are increasingly used
to determine the spatio-temporal activation patterns during AF and have revealed the presence of multiple
rotational and focal sources of activation. Targeting these sources with localized ablation results in acute
termination in roughly 30-35% of patients but can result in long-term freedom of AF that is much higher than
other therapies (75-80%). It is currently not clear why some patients do not terminate acutely, which source
drives AF, and which source should be targeted first.
We propose to develop a quantitative analysis of the temporal stability and the strength of the rotational and
focal sources. We will use an existing and extensive data set of unipolar recordings that used a 64-pole
basket electrode that covered most of the atrium. We will consider two groups of patients: one in which
targeted ablation at sites of rotational or focal activity terminated AF and one in which it did not. We will
construct phase maps using a methodology based on a previously published study and will develop
algorithms that can quantify the strength and temporal stability of the sources. A comparison between the
two groups will allow us to determine whether the elimination of sources with greater strength or stability
can predict the result of targeted ablation. Our findings will then be tested in a validation cohort. Our study
should result in improved targeted ablation strategies, enabling and advancing the development of better
therapeutic strategies for AF.

## Key facts

- **NIH application ID:** 9978611
- **Project number:** 5R21HL145500-02
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN DIEGO
- **Principal Investigator:** WOUTER-JAN RAPPEL
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $118,125
- **Award type:** 5
- **Project period:** 2019-07-15 → 2021-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9978611

## Citation

> US National Institutes of Health, RePORTER application 9978611, Determining strength and temporal stability of rotational and focal sources during human atrial fibrillation (5R21HL145500-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9978611. Licensed CC0.

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