Figure 1. Area of heart included within the radiation field (50% isodose line). Circular white markers (white arrows) correspond to the radiation field tattoos, whereas the solid white line corresponds to the radiation therapy posterior field edge. Radiation portals for the left breast lie anterior to this line. This example shows the decrease in cardiac involvement with breath holding at deep inspiration (b) relative to baseline end-tidal volume (a) at the same anatomic level. LV indicates left ventricle.
Dr. Ming Hui Chen additionally established a new easy-to-implement respiratory maneuver in 1997 to reduce the amount of cardiac tissue exposed to radiation during left-breast radiation therapy. Full inspiratory breath-holding resulted in a decrease in cardiac volume included in the left-breast radiation portals. While absolute magnitude of cardiac volume within left-breast radiation portals with different respiratory maneuvers may be affected by arm position differences between MRI scanning and radiation therapy treatment position, they found that deep inspiratory breath-holding decreases cardiac volume in all subjects was maintained regardless of arm position.
Because the pericardium is firmly attached to the diaphragm, full inspiration pulls both the diaphragm and heart inferiorly while expanding the chest cavity; as a result, cardiac volume involvement in the radiation field decreases. In contrast, forced expiration elevates the diaphragm, moving the heart superiorly and anteriorly toward the chest wall, thereby increasing cardiac volume in the radiation portals.
Chen et al, 1997, Circulation
Figure 2. Change in cardiac volume (cm3) vs ETid that is included in the left-breast radiation field with respiratory maneuvers. The figure shows individual inspiratory (Insp) and forced expiratory (Exp) data compared with baseline ETid. Note that inspiration substantially and consistently reduces the volume of heart within the radiation portals, whereas expiration leads to an increase in cardiac involvement.
In conclusion, they found that inclusion of cardiac volume in the left-breast radiation therapy field is common. Use of inspiratory maneuvers significantly decreases cardiac volume within the radiation portals. All attempts to minimize cardiotoxicity are especially relevant for long-term breast cancer survivors because cardiovascular disease remains the leading cause of mortality in women after menopause. The implementation of simple inspiratory breath holding during delivery of radiation therapy may preserve radiation dosage to the breast while reducing cardiac involvement and deserves further study.
Excerpted from: Impact of Respiratory Maneuvers on Cardiac Volume Within Left-Breast Radiation Portals
Ming Hui Chen, Michael L. Chuang, Bruce A. Bornstein, Rebecca Gelman, Jay R. Harris, and Warren J. Manning
Read more of Dr. Chen's work in cardio-oncology and breast cancer
Chen MH, Chuang ML, Bornstein BA, Gelman R, Harris JR, Manning WJ. Impact of respiratory maneuvers on cardiac volume within left-breast radiation portals. Circulation. 1997 Nov 18;96(10):3269-72. doi: 10.1161/01.cir.96.10.3269. PMID: 9396414. [Excerpted above]
Lu HM, Cash E, Chen MH, Chin L, Manning WJ, Harris J, Bornstein B. Reduction of cardiac volume in left-breast treatment fields by respiratory maneuvers: a CT study. Int J Radiat Oncol Biol Phys. 2000 Jul 01; 47(4):895-904. PMID: 10863057.
Tanguturi SK, Lyatskaya Y, Chen Y, Catalano PJ, Chen MH, Yeo WP, Marques A, Truong L, Yeh M, Orlina L, Wong JS, Punglia RS, Bellon JR. Prospective assessment of deep inspiration breath-hold using 3-dimensional surface tracking for irradiation of left-sided breast cancer. Pract Radiat Oncol. 2015 Nov-Dec; 5(6):358-65. PMID: 26231594.
B. Aleman, L. Specht, MH Chen. Heart, Coronary Arteries, Aorta and Great Vessels, Arteries and Veins, Microcirculation. In: ALERT—Adverse Late Effects of Cancer Treatment, Volume 2: Specific Normal Tissue Sites. (Editors: P Rubin, LS Constine, LB Marks, JP Williams, and JT Hansen). Springer 2013 [Not pictured].