A 3-day-old female infant born at term presents for evaluation of a cardiac murmur detected on routine newborn screening. Her mother has a history of Turner syndrome. On examination, the infant is afebrile with BP 68/42 mmHg, HR 152 bpm, RR 41/min, and SpO2 99% on room air. A systolic ejection murmur is heard best at the right upper sternal border. Echocardiography reveals a bicuspid aortic valve with a peak instantaneous gradient of 32 mmHg across the valve. Left ventricular wall thickness and cavity dimensions are currently normal. The aortic valve shows no regurgitation. The cardiologist counsels the family regarding the natural history of progressive aortic stenosis. Which of the following pathophysiologic changes occurs earliest in the progression of hemodynamically significant aortic stenosis?
- A)Eccentric left ventricular hypertrophy with chamber dilation
- B)Concentric left ventricular hypertrophy due to increased afterloadGABARITO
- C)Secondary aortic regurgitation from leaflet prolapse
- D)Pulmonary edema from elevated left atrial filling pressures
- E)Aortic root dilatation from chronic turbulent flow
Explicação
In progressive aortic stenosis, increased afterload from obstruction to left ventricular outflow causes the LV myocardium to respond with concentric hypertrophy as an adaptive mechanism to maintain ejection fraction and reduce wall stress (Laplace's law). This... Ver explicação completa e trilha adaptativa →