Sparing The Heart with Deep Inspiration breath-hold

Improvements in breast cancer diagnosis and treatment mean that patients are living longer after the diagnosis of breast cancer than ever before. This has drawn attention to issues that patients may face as long term survivors of cancer.

One of these issues is the possibility of heart disease following treatment. This may arise from drugs such as anthracyclines, 5-FU, taxanes, trastuzumab and letrozole or from radiation therapy.

Deep inspiration breath-hold (DIBH) is a radiotherapy procedure to reduce the risk of radiation induced heart disease. In this technique, patients take a deep breath and hold it while the radiation is administered. Since the lungs are filled with air when the patient has taken in a deep breath in, the heart moves away from the chest and becomes narrower, both of which reduce the radiation dose being received by the heart.

DIBH may either be voluntary or utilise a device called spirometer, a device that controls the air inhaled using which allows for the monitoring of air flow during the respiratory cycle and the halting of air flow at a predetermined volume, requiring the patient to hold their breathing to sustain this volume.

In voluntary breath hold, patients undergo assessment to determine how long they can hold their breath. Following this, most patients undergo training for a few days, though yoga practitioners and swimmers may get away without, as they are already trained in holding their breath!

During radiotherapy planning and simulation, at least two CT scans matching to free breathing and DIBH are obtained. The patient’s contours or the “target” and normal organs are drawn on both CT scans, and two radiation plans are generated to identify how much the heart dose can be reduced while ensuring that the region identified as the target receives the same dose. During treatment, the radiation is turned on only when the patient holds her breath in deep inspiration.

Several focused dosimetric comparisons have found DIBH to be beneficial, particularly in terms of heart dosage parameters. When comparing the same patients scheduled with free breathing and DIBH, DIBH leads to considerable reductions in both mean heart doses and mean LAD doses, with decreases of 25–67 and 20–73%, respectively (Bergom et. al. 2018), the LAD or left anterior descending artery being the main blood vessel supplying the muscles of the heart.

DIBH necessitates the use of well-trained and experienced radiation oncologists, physicists and radiotherapy technologists to conduct therapy.

Patients having left-sided breast cancer tend to have higher cardiac mortality merely owing to the target's closeness to the heart and benefit the most from the DIBH approach.

Reference:

Bergom, C., Currey, A., Desai, N., Tai, A., & Strauss, J. B. (2018). Deep Inspiration Breath Hold: Techniques and Advantages for Cardiac Sparing During Breast Cancer Irradiation. In Frontiers in Oncology (Vol. 8). Frontiers Media SA. https://doi.org/10.3389/fonc.2018.00087