Interventional Radiology Techniques Used in Cardiomyopathies

Introduction

Various cardiomyopathies can be evaluated for their effects on the structure and function of the heart using recent modern and advanced imaging techniques. Echocardiography and cardiac magnetic resonance imaging are frequently employed in modern cardiology practice to provide a fundamental framework for evaluating and treating cardiomyopathies.

What Are Cardiomyopathies?

Cardiomyopathy is a condition that affects the heart muscle (myocardium). The heart's capacity to effectively pump blood is reduced as a result of cardiomyopathy. Cardiomyopathy results in heart enlargement, stiffness of the heart, and thickening of the heart walls. It also results in arrhythmias (irregular heartbeats).

• Dilated Cardiomyopathy (DCM) - The heart muscles are dilated. In dilated cardiomyopathy (DCM), the heart's left ventricle (lower left chamber) enlarges (dilates) and the heart's ability to contract is impaired, resulting in less blood being pumped to the body.

• Hypertrophic Cardiomyopathy (HCM) - Thickening of the heart muscles occurs particularly in the left ventricles. Muscle thickening may make it more difficult for the heart to receive and expend an adequate amount of blood. Blood flow from the left ventricle to the aorta may occasionally become obstructed due to muscle hypertrophy.

• Restrictive Cardiomyopathy - Scarring and stiffening of the heart muscles occur.

• Left Ventricular Non-compaction Cardiomyopathy - In left ventricular non-compaction cardiomyopathy (LVNC), bundles or individual pieces of muscle extend into the left ventricle, the lower left chamber of the heart. These muscle fragments are known as trabeculations.

• Arrhythmogenic Cardiomyopathy - Irregular heartbeats occur.

What Is Interventional Radiology?

An advanced medical imaging technique called interventional radiology is used to identify specific blood vessels and lymph vessels in the body. An interventional radiologist is required to execute every interventional radiology operation. A doctor with specialized training in employment of imaging equipment for specific treatments is known as an interventional radiologist. Interventional radiology procedures are minimally invasive and use a small incision and imaging equipment. Many of these techniques would have required invasive surgery in the past.

What Are the Various Interventional Radiology Techniques Used in Cardiomyopathies?

• Echocardiography:

  • It is typically the first diagnostic imaging modality of choice in patients with known or suspected cardiomyopathy due to its exceptional capacity to provide real-time images of the beating heart along with its noninvasiveness, images with a high spatiotemporal resolution, cost-effectiveness, availability, and portability. It is incredibly helpful in determining the structure and function of the heart, giving a precise evaluation of the chamber size, wall thickness, ejection fraction (EF), diastolic function, valvular function, estimates of intracardiac and pulmonary artery pressures, stroke volume, cardiac output, and abnormalities in wall motion. Echocardiography not only significantly influences the diagnosis of cardiomyopathies but also advances the knowledge of the underlying pathobiology. The various echocardiographic techniques used in the evaluation of cardiomyopathies are:

  • Two-Dimensional Echocardiography - It is used to calculate the size and function of the heart chambers. The wall thickening and endocardial motion of the myocardial segment are used to evaluate regional myocardial function.

  • Spectral and Tissue Doppler Echocardiogram - Modern cardiomyopathies must be evaluated using echocardiography with doppler hemodynamic assessment, which measures diastolic function, pulmonary artery, right, and left atrial (LA) pressures, volumetric assessment of left ventricular stroke volume, and, if present, quantification of regurgitant valve defects.

  • Contrast Echocardiography - The use of contrast agents during echocardiography can improve assessments of cardiac function and structure. It is made up of microbubbles, which scatter ultrasonic waves more effectively than red blood cells, increasing the strength of the returning signal to improve blood pool imaging. The contrast agents that go through the circulation can be utilized to highlight left ventricular structural defects, the left ventricular chamber, and myocardial perfusion.

  • Three-Dimensional Echocardiography - The imaging technique represents a significant advancement in cardiovascular ultrasonography. Improvements in computer and transducer technologies enable real-time three-dimensional capture and presentation of heart structures from any spatial point of view.

• Cardiac Magnetic Resonance Imaging:

  • Cardiac magnetic resonance imaging helps in the assessment of various cardiomyopathies. Additionally, it offers details on the underlying cause, potentially modifiable elements of the illness processes, and biventricular volumes and function. A thorough cardiac magnetic resonance imaging evaluation makes use of a variety of imaging methods, including T1- and T2-weighted sequences for tissue characterization, cine functional analysis, late gadolinium enhancement (LGE) for infarct/fibrosis imaging and contrast-enhanced myocardial perfusion imaging.

  • The understanding of dilated cardiomyopathy, myocarditis, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, iron-overload cardiomyopathy, amyloidosis, sarcoidosis, and left ventricular non-compaction cardiomyopathy has been significantly aided by the useful role of cardiac magnetic resonance imaging in cardiomyopathies. The evaluation of left ventricular structure and function, tissue characterization, particularly the presence and amount of fibrosis, and left ventricular thrombus are the main areas of focus for contemporary cardiac magnetic resonance imaging techniques used in the assessments of cardiomyopathies.

• Nuclear Medicine:

  • Cardiomyopathy can also be evaluated using nuclear medicine particularly since single-photon emission computed tomography (SPECT) makes it possible to assess myocardial perfusion. For assessing coronary artery disease (CAD), SPECT is highly accurate and also offers prognostic data.

  • Further applications of nuclear imaging techniques include study of the left ventricle (LV), and the identification of various cardiomyopathy subtypes. It is also helpful in understanding the viability of myocardium using positron emission tomography (PET).

  • The drawbacks of nuclear imaging include the use of ionizing radiation, restricted spatial resolution, inadequate tissue characterization, and relatively lengthy imaging durations.

• Computed Tomography:

  • While evaluating cardiomyopathies, computed tomography is not frequently regarded as a first-line imaging modality. Nonetheless, it is becoming more and more significant, especially in individuals who are ineligible for (magnetic resonance imaging is contraindicated) or receive subpar findings from conventional imaging procedures, like echocardiography due to poor acoustic window.

  • The majority of scans are completed in a couple of seconds with computed tomography, which is widely accessible and has a quick turnaround. Modern scanners have a high temporal resolution of up to 66 milliseconds and outstanding spatial resolution for evaluating even tiny features like coronary arteries. The evaluation of coronary arteries, which is a crucial part of evaluating cardiomyopathy and may be done with computed tomography angiography (CTA), is excellent. Before and after therapy, CT can be utilized to characterize particular tissues and give functional evaluation. The use of ionizing radiation and iodinated contrast material is among the main drawbacks of CT. Patients with renal impairment and contrast allergies should utilize iodinated contrast with caution.

Conclusion

The latest advancement in interventional radiology offers a thorough evaluation of several aspects of cardiomyopathies, including phenotypic characterization, coronary artery evaluation, function measurement, therapy planning, and post-treatment evaluation.