Shockwave Strain: Treatment vs. Diagnosis in Cardiology
Understand the relationship between a diagnostic tool that assesses heart muscle performance and a therapy that prepares arteries for stenting.
The term “shockwave strain” can be confusing as it combines two separate cardiology technologies. One is a diagnostic tool that measures heart muscle function, while the other is a therapeutic procedure used to treat hardened arteries. This article will clarify these two concepts, explaining what each is and how they are used together to manage heart health.
Measuring Heart Function with Strain Imaging
Myocardial strain imaging is a non-invasive diagnostic test that assesses the function of the heart muscle. It provides a detailed look at how the heart muscle deforms, or changes shape, during each heartbeat. This deformation is a direct indicator of the muscle’s health and pumping efficiency. Doctors use this technique to detect subtle changes in heart function that might not be apparent with other methods.
The most common method for this is speckle-tracking echocardiography, which uses standard ultrasound images of the heart. This technology analyzes the motion of naturally occurring patterns, or “speckles,” within the heart muscle tissue. By tracking these speckles, the system can precisely calculate the degree and rate of myocardial deformation, providing a quantitative measure of function in different segments of the heart.
This detailed assessment offers information beyond traditional measures like ejection fraction. Global longitudinal strain (GLS), a key parameter from this imaging, is a more sensitive marker for detecting early signs of heart muscle weakness. It allows cardiologists to identify subclinical heart problems, monitor patients undergoing treatments that could affect the heart, and evaluate conditions like cardiomyopathy and heart failure with greater precision.
Treating Arteries with Shockwave Therapy
Shockwave Intravascular Lithotripsy (IVL) is a treatment designed to manage severely calcified plaque inside coronary arteries. Unlike strain imaging, which is a diagnostic tool, IVL is a therapeutic procedure used to prepare a blocked artery for stenting. The technology is adapted from the method used to break up kidney stones and uses a specialized balloon catheter to deliver sonic pressure waves to the hardened plaque.
The procedure involves guiding the IVL catheter to the site of the calcified blockage. Once in position, an electrical discharge within the catheter vaporizes fluid inside the balloon, creating a small bubble that rapidly expands and collapses. This action generates powerful but brief acoustic shockwaves that travel through the artery wall to crack the hard calcium deposits without damaging soft vascular tissue.
By fracturing both superficial and deep calcium, the therapy restores some flexibility to the artery wall. This allows a subsequent balloon angioplasty to expand the artery more effectively. Following the shockwave treatment, a stent can be inserted and fully expanded to restore adequate blood flow. Without this step, hard calcium can prevent a stent from opening properly, leading to potential complications.
The Clinical Connection
The insights from strain imaging and the application of shockwave therapy often intersect within a patient’s treatment journey. The process may begin when a patient presents with symptoms like chest pain or shortness of breath. A cardiologist might then order an echocardiogram with myocardial strain imaging to evaluate the heart’s mechanical function.
The strain imaging results could reveal that a specific segment of the heart wall is not contracting properly. For example, the global longitudinal strain value might be lower than normal, pointing toward subclinical dysfunction even if the overall ejection fraction appears adequate. This finding would prompt further investigation to determine the cause.
Subsequent tests, such as a coronary angiogram, might then uncover a severe blockage in an artery supplying blood to that area of the heart. If this blockage is heavily calcified, it presents a challenge for standard stenting. The hardened plaque can prevent the stent from expanding correctly.
This is the clinical scenario where shockwave IVL becomes an option. A physician would use the shockwave catheter to first fracture the calcium, making the lesion more pliable. After the lithotripsy modifies the plaque, an interventional cardiologist can proceed with placing a stent. This integrated approach ensures the vessel is properly opened, restoring blood flow to the compromised heart muscle.