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by Audrey Mendenhall RT, RVT, RDCS, RDMS
Sound Health Imaging
Mankind has always had a passion for things of the heart. The Greeks believed the heart was the seat of the spirit. Chinese believe the heart is the center for happiness. Egyptians thought the emotions and intellect comes from the heart. In American culture the heart has a multiplicity of meanings. We respect someone who “has a lot of heart” for they have an admirable internal drive to accomplish a goal. We sometimes describe a generous or kind person as having a “heart of gold”. Lovers “steal hearts”, “break hearts”, “win hearts”, or love “with all of their heart”. Those who are selfish in a relationship are deemed “heartless”. A “cold heart” describes someone who is distant and unloving. A person might have a “change of heart” that keeps them from pursuing a previous interest. When we are sharing feelings we are having a “heart to heart” conversation, and all of us hope to achieve our “heart’s desire”. Some are accused of “wearing their heart on their sleeve” and being too easily offended. We place our hand over our heart while we recite the Pledge of Allegiance or sing our National Anthem. Even schoolyard children “cross my heart and hope to die…” when making a pact to keep a secret.
Yet with all of the discussions involving the heart we so often take for granted this amazing organ. The heart is the center of the bodies’ circulatory system, which is made up of the heart arteries, veins and capillaries. It pumps blood to the lungs to be oxygenated. It then pumps the oxygen rich blood to the brain and body. In the process the heart beats approximately one hundred thousand times every day. That equates to 35 million times per year. In an average lifetime, the heart will beat approximately 2.5 billion times, and pump approximately 1 million barrels of blood! On average the adult heart beats 72 beats per minute while a child’s ranges from 90-120 beats per minute. A woman’s heart weighs approximately 8 ounces and a man’s 10 ounces. The size of an adult heart is equal to the size of two of their fists, and the size of a kid’s heart equals the size of one of their fists.
The heart begins to beat at approximately 28 days in the early stages of development in the womb. It is at this time that a beating heart is discerned by ultrasound. Expectant parents can see and hear their baby’s heartbeat on ultrasound at this early stage and the pregnancy is considered viable. Once a fetal heart beat is detected, the chance of miscarriage decreases dramatically. At 6 weeks the fetal heart rate is approximately 100 beats per minute but increases rapidly in the next few weeks. The normal fetal heart rate can range anywhere from 100 beats per minute to 185 beats per minute. The fetal heart is the size of a chickpea at 12 weeks. It is about the size of an olive at 22 weeks, and by 32 weeks it is the size of an almond.
Most pregnant women have a “fetal anatomical survey” ultrasound done between 18 and 22 weeks of their pregnancy. This 18-22 week scan provides a wealth of information about the pregnancy. This is still a good time to date a pregnancy so measurements are done of the fetal head, abdomen and femur. Fetal anatomy is also evaluated including the fetal heart. The ability to visualize fetal anatomy during second-trimester ultrasound exams has improved dramatically thanks to major technological advances. In the early days of ultrasound, only fetal heart motion could be detected. As technology improved more details of the fetal heart anatomy could be visualized with ultrasound. Currently, not only can the heart motion be seen and heard, but all 4 chambers of the heart are documented. It is now also possible to visualize the aorta arising from the left ventricle and the pulmonary artery from the right. The returning veins entering the right and left atria are readily visualized, as well as, the aortic arch and its branches. Using pulsed wave doppler during the ultrasound exam an EKG of the fetal heart can be done to demonstrate normal heart rhythm.
Prenatal diagnosis of congenital heart disease is crucial to optimal obstetric and neonatal care. Congenital heart disease is the most common severe congenital abnormality found among live births. It is said to occur in approximately 1 in 100 live births. Identification of a congenital heart defect allows a variety of treatment options and preparation for the expectant parents. With technological advances in obstetrical ultrasound, virtually all major congenital heart defects are detected. It should be borne in mind that at 20 weeks the fetal heart is a very small structure; it’s about the size of a quarter. Small defects may be overlooked due to poor fetal position, or maternal body size. Also, the baby’s circulatory system will undergo some changes immediately following delivery that may reveal a subtle abnormality not detectable while in the womb. In spite of these potential pitfalls, a normal fetal heart visualized on ultrasound provides reassurance for both expectant parents and their physician.
The Latin word for heart is cor. Truly the heart is at the core of our being. One can’t live or love without it!