A 16-year-old girl presents with a sensation of “skipped beats” in her chest, which are more frequent when she is feeling anxious. Her physical exam and medical history are unremarkable. An ECG shows occasional, uniform premature ventricular contractions that disappear when she runs in place in the clinic. What is the most likely significance of these findings?
A 5-year-old child with a history of unrepaired supracristal ventricular septal defect presents for evaluation. On examination, a new early diastolic decrescendo murmur is heard at the mid-left sternal border in addition to the known holosystolic murmur. What is the most likely cause of this new finding?
A researcher develops a mouse model with a targeted disruption of the transcription factor gene HAND1. The goal is to study the embryologic origins of specific congenital heart defects. Based on the known function of this gene, which structural abnormality is most likely to be observed in these mice?
A 10-year-old boy presents to the emergency department after a syncopal episode that occurred while he was swimming in a race. His baseline ECG shows a QTc of 0.49 seconds. A diagnosis of Long QT syndrome is suspected. A syncopal event induced by exertion, such as swimming, is most characteristic of which genotype?
A 4-year-old boy is brought for a routine check-up where a heart murmur is detected. The murmur is described as medium-pitched, vibratory, and “musical,” heard best along the left sternal border. The intensity of the murmur diminishes significantly when the child moves from a supine to a sitting position. What is the most likely diagnosis?
An electrocardiogram is performed on a healthy, asymptomatic 3-day-old term neonate. The tracing shows a heart rate of 140 beats/min, a QRS axis of +150 degrees, and prominent, upright T waves in lead V1. What is the most appropriate interpretation of these electrocardiogram findings?
A 6-year-old girl is referred for evaluation of a heart murmur. On examination, she is acyanotic and well-developed. You hear a grade II/VI systolic ejection murmur at the upper left sternal border and note that the second heart sound is widely split and does not change its splitting pattern with respiration. Which diagnosis do these physical exam findings most strongly suggest?
An 8-month-old infant is brought to the clinic for poor weight gain. The mother reports that the infant breathes rapidly, sweats profusely, and takes over 45 minutes to finish a bottle, after which he seems exhausted. These symptoms have been present since he was about a month old. These symptoms are most characteristic of which condition in an infant?
A 1-month-old infant, whose mother had a documented rubella infection during the first trimester of pregnancy, is evaluated. The infant has a continuous murmur heard best beneath the left clavicle, along with bounding peripheral pulses and a wide pulse pressure. Which cardiac lesion is most strongly associated with this clinical picture and maternal history?