Heart murmurs that increase with increased preload (increased venous return to the heart) are typically associated with conditions that cause increased flow across a valve or defect, as preload augments cardiac output. These maneuvers include leg raising, squatting, or volume expansion, which increase venous return. The murmurs that characteristically increase with increased preload include:

1. Mitral regurgitation (MR): A holosystolic murmur at the apex, radiating to the axilla. Increased preload increases left ventricular volume, worsening regurgitation across the mitral valve.
2. Aortic regurgitation (AR): A diastolic decrescendo murmur at the left sternal border. Increased preload increases stroke volume, amplifying the regurgitant flow.
3. Ventricular septal defect (VSD): A holosystolic murmur at the left sternal border. Increased preload increases shunting across the defect, intensifying the murmur.
4. Atrial septal defect (ASD): A systolic ejection murmur with fixed splitting of S2, often at the left upper sternal border. Increased preload enhances right ventricular volume and pulmonary flow, accentuating the murmur.
5. Mitral stenosis (MS): A diastolic rumble at the apex. Increased preload increases left atrial pressure and flow across the stenotic valve, making the murmur louder.
6. Aortic stenosis (AS) (to a lesser extent): A systolic ejection murmur at the right upper sternal border. While primarily affected by afterload, increased preload can increase stroke volume, slightly intensifying the murmur in some cases.

Key maneuvers that increase preload (e.g., squatting or leg raising) contrast with maneuvers like Valsalva or standing, which decrease preload and typically reduce these murmurs. Always consider the clinical context and associated findings for accurate diagnosis.

Disclaimer: owerl is not a doctor; please consult one.