Bigeminy is a cardiac arrhythmia in which there is a single ectopic beat, or irregular heartbeat, following each regular heartbeat. Most often this is due to ectopic beats occurring so frequently that there is one after each sinus beat, or normal heartbeat. The two beats are figuratively similar to two twins (hence bi- + gemini). For example, in ventricular bigeminy, a sinus beat is shortly followed by a premature ventricular contraction (PVC), a pause, another normal beat, and then another PVC. In atrial bigeminy, the other "twin" is a premature atrial contraction (PAC). Cause
After any PVC there is a pause that can lead to the development of bigeminy. A PVC wavefront often encounters a refractory AV node that does not conduct the wavefront retrograde. Thus the atrium is not depolarized and the sinus node is not reset. Since the sinus P wave to PVC interval is less than the normal P–P interval, the interval between the PVC and the next P wave is prolonged to equal the normal time elapsed during two P–P intervals. This is called a "compensatory" pause. The pause after the PVC leads to a longer recovery time, which is associated with a higher likelihood of myocardium being in different stages of repolarization. This then allows for re-entrant circuits and sets up the ventricle for another PVC after the next sinus beat.
The medical history should include physical and mental health problems, prescription and non-prescription medication use, nutritional supplement use, history of alcohol and substance use, childhood adversities, cultural and social beliefs, past traumatic experiences, and infectious diseases such as HIV. Since the medical history of the birth giver may not be available immediately after delivery, some testing needs to be done in the infant to confirm possible exposure. Infants urine, meconium, umbilical cord tissue or hair can be used for testing. The timing of urine sample collection is critical because some drugs may become undetectable after they are metabolized and eliminated from the body. Also, urine test results can only confirm if the fetus was exposed to drugs a few days before birth. Meconium testing can be used to confirm drug exposure in earlier stage of pregnancy, but the collecting process is more difficult. Umbilical cord tissue testing is a relatively new testing method and its accuracy is still controversial. The mothers blood and urine sample should also be collected for drug screening. Chest X-rays can confirm or infirm the presence of heart defects. Assessment
Depending on what hospital setting the infant is in, different scoring systems are used for assessing the severity and the need for medication treatment in neonatal withdrawal syndrome. One challenge with existing clinical predication tools is that they were designed to assess opiate withdrawal only. The Finnegan Neonatal Abstinence Scoring System (FNASS), or its modified version is the most widely used prediction tool currently in the United States.