Which cardiac murmurs increase with handgrip and why?

From the Guidelines

Handgrip increases the intensity of murmurs associated with mitral regurgitation, ventricular septal defects, and aortic regurgitation. During handgrip exercise, there is increased systemic vascular resistance as the muscles contract, which leads to increased afterload on the left ventricle. This increased afterload causes a rise in left ventricular pressure, which then amplifies the pressure gradient across any existing regurgitant or defective pathways. In mitral regurgitation, the higher left ventricular pressure forces more blood backward through the incompetent mitral valve into the left atrium, intensifying the murmur. Similarly, in ventricular septal defects, the increased left ventricular pressure enhances the left-to-right shunt across the defect, making the murmur louder. Conversely, murmurs like aortic stenosis and hypertrophic cardiomyopathy typically decrease with handgrip because the increased afterload reduces the pressure gradient across the aortic valve or outflow tract. Understanding these hemodynamic responses helps clinicians differentiate between various cardiac murmurs during physical examination, providing valuable diagnostic information without requiring immediate advanced imaging, as supported by the guidelines outlined in 1.

Some key points to consider when evaluating cardiac murmurs with handgrip include:

• The effect of handgrip on murmurs associated with different valvular lesions
• The role of increased afterload in modifying murmur intensity
• The distinction between murmurs that increase and those that decrease with handgrip
• The clinical utility of handgrip exercise in the physical examination of patients with suspected valvular heart disease, as discussed in 1.

It is essential to recognize that the response of cardiac murmurs to handgrip exercise can provide valuable insights into the underlying cardiac pathology, guiding further diagnostic evaluation and management, as emphasized in the guidelines 1.

From the Research

Cardiac Murmurs and Handgrip

• Cardiac murmurs that increase with handgrip are typically associated with hypertrophic cardiomyopathy (HCM) and dynamic left ventricular outflow tract (LVOT) obstruction 2.
• During handgrip, heart rate, systolic blood pressure, and cardiac output increase significantly, which can exacerbate LVOT obstruction in patients with HCM 2.
• The increase in cardiac murmur intensity with handgrip is due to the increased contractility and outflow tract obstruction that occurs in response to the isometric exercise 2.

Mechanism of Increased Murmur

• The mechanism of increased murmur with handgrip is thought to be related to the increased systemic vascular resistance and decreased end-systolic volume that occurs in response to isometric exercise in patients with HCM 2.
• The abnormal adaptation to load changes in HCM patients, compared to control subjects, contributes to the increase in murmur intensity with handgrip 2.

Other Factors Influencing Murmur Intensity

• Other factors that can influence murmur intensity include the presence of a large pleural effusion, which can cause dynamic LVOT obstruction due to systolic anterior motion of the mitral valve 3.
• Novel methods of provocation, such as physiological stress tests and upright exercise, can be used to disclose patients with nonobstructive hypertrophy in resting conditions and hard, but possible provoking obstruction 4.