Cardiac Output Regulation

A 52-year-old man with chronic hypertension presents with dyspnea on exertion. Echocardiography reveals left ventricular hypertrophy with preserved ejection fraction. Which of the following is the most common mechanism by which increased afterload reduces cardiac output in this patient?

During a cardiovascular physiology practical, a student observes that in a healthy volunteer, the most common compensatory response to an acute 20% reduction in blood volume is an increase in which of the following?

A 58-year-old man with a 10-year history of hypertension presents to the emergency department with acute dyspnea, orthopnea, and bilateral ankle edema. His blood pressure is 165/105 mmHg, heart rate 112 bpm, and JVP is elevated at 8 cm H₂O. Echocardiography reveals a left ventricular ejection fraction (LVEF) of 35% with global hypokinesis. Cardiac catheterization shows elevated pulmonary capillary wedge pressure (PCWP) of 28 mmHg. Which of the following mechanisms BEST explains the reduced cardiac output in this patient?

A 42-year-old woman with severe anemia (hemoglobin 6.5 g/dL) secondary to chronic GI bleeding presents with palpitations and dyspnea on exertion. Her heart rate is 110 bpm, blood pressure 118/72 mmHg, and cardiac output (measured by thermodilution) is 6.8 L/min (normal 4–5 L/min). After transfusion to Hb 10 g/dL, her heart rate falls to 92 bpm and cardiac output decreases to 5.2 L/min. Which of the following BEST explains the physiologic basis for the elevated cardiac output in severe anemia?

A 52-year-old man with a history of hypertension presents with dyspnea and orthopnea. Echocardiography reveals reduced ejection fraction (35%) with dilated left ventricle. Which of the following is the most common compensatory mechanism initially responsible for maintaining cardiac output in chronic heart failure?