Does heart failure secondary to Rheumatic Heart Disease (RHD) typically cause increased cardiac output?

Heart Failure Secondary to Rheumatic Heart Disease Does Not Cause Increased Cardiac Output

Heart failure secondary to Rheumatic Heart Disease (RHD) typically causes decreased cardiac output, not increased cardiac output. 1

Pathophysiology of Heart Failure in RHD

• Heart failure is characterized by a reduced ability to perform aerobic exercise due to inadequate blood flow to active skeletal muscle secondary to impaired cardiac output 1
• Patients with heart failure may achieve only 50% of the maximal cardiac output attained by healthy individuals at peak exercise 1
• In heart failure, stroke volume is already decreased at rest and rises only modestly during exertion compared to healthy individuals 1
• The inability to increase cardiac output is primarily related to minimal increase in stroke volume coupled with a lower maximal heart rate achieved at a lower workload 1

Types of Heart Failure and Cardiac Output

• Heart failure can be categorized as high-output or low-output, but RHD typically leads to low-output heart failure 1
• High-output heart failure refers to conditions that mimic heart failure symptoms but are not primarily cardiac diseases, such as anemia, thyrotoxicosis, septicemia, liver failure, arteriovenous shunts, Paget's disease, and beri-beri 1
• RHD causes structural and functional abnormalities of the heart valves, leading to traditional low-output heart failure 2, 3

Hemodynamic Changes in RHD-Related Heart Failure

• In RHD, valvular damage (particularly mitral and aortic regurgitation) leads to volume overload and eventually decreased forward cardiac output 4
• The dilated left ventricle in RHD-related heart failure operates near its maximal volume, exhausting most of its preload reserve 1
• The failure to increase left ventricular systolic emptying derives from impaired intrinsic contractility, reduced β-adrenergic responsiveness, elevated systemic vascular resistance, and blunted peripheral arterial vasodilator response to exercise 1
• Mitral regurgitation, common in RHD, reduces forward stroke volume during exercise 1

Right-Sided Heart Failure in RHD

• RHD can lead to right-sided heart failure, which is associated with decreased cardiac output and progressive end-organ damage 1
• Right ventricular dysfunction in RHD contributes to reduced cardiac output through ventricular interdependence, where right ventricular dilation causes leftward shift of the interventricular septum, impairing left ventricular filling 1
• The combination of right ventricular systolic and biventricular diastolic dysfunction reduces cardiac output, impairs coronary blood flow, and exacerbates peripheral and abdominal congestion 1

Clinical Manifestations Related to Reduced Cardiac Output

• Decreased exercise tolerance resulting from reduced cardiac output is a common complaint among patients with heart failure secondary to RHD 5
• Tissue hypoperfusion due to decreased cardiac output is a key aspect of heart failure in RHD 5
• Clinical signs of low cardiac output include hypoxia, cyanosis, oliguria, and altered mental status in severe cases 6

Common Pitfalls in Understanding Heart Failure in RHD

• Do not confuse RHD-related heart failure with high-output heart failure states that can mimic heart failure symptoms 1
• Remember that while RHD typically causes low-output heart failure, the clinical presentation may sometimes resemble high-output states due to valvular regurgitation, but the forward cardiac output remains reduced 4
• Treatment approaches should focus on addressing the reduced cardiac output through appropriate medical therapy and consideration of valve surgery when indicated 2