Image Processing for Automated Diagnosis of Cardiac Diseases

Image Processing for Automated Diagnosis of Cardiac Diseases highlights current and emerging technologies for the automated diagnosis of cardiac diseases. It presents concepts and practical algorithms, including techniques for the automated diagnosis of organs in motion using image processing.

This book is suitable for biomedical engineering researchers, engineers and scientists in research and development, and clinicians who want to learn more about and develop advanced concepts in image processing to overcome the challenges of automated diagnosis of heart disease.

• Includes advanced techniques to improve diagnostic methods for various cardiac diseases
• Uses methods to improve the existing diagnostic features of echocardiographic machines
• Develops new diagnostic features for echocardiographic machines

• Language: English
• Publisher: Academic Press
• Release date: Jul 13, 2021
• ISBN: 9780323850650

Book preview

Chapter 1: Cardiac diseases and their diagnosis methods

Kalpana Chauhana; Rajeev Kumar Chauhanb    a Department of Electrical Engineering, Central University of Haryana, Mahendragarh, India

b Department of Electrical Engineering, Dayalbagh Educational Institute, Agra, India

Abstract

This chapter discusses different heart diseases, which are abnormalities that affect normal functioning of the electrical system, valves, muscles, and arteries of the heart. The main focus is on mitral valve disease, which is the second most common valvular lesion, preceded only by aortic stenosis (AS). Study of mitral regurgitation (MR) is understood to cover all other mitral valve diseases. If MR does not progress, then the amount of regurgitation is small (i.e., MR is mild with less backward leakage). However, if there is significant MR, then the left ventricle must do more work to fulfill the oxygenated blood demand of the body. The long period of this disease may lead to heart failure, therefore early diagnosis is important. As such, this chapter highlights some special diagnostic methods, including different types of echocardiography.

Keywords

Heart valve; Coronary arteries; Mitral valve; Aortic stenosis; Mitral regurgitation; Echocardiography

Chapter outline

1.1Introduction

1.2Heart valves

1.3Mitral valve regurgitation

1.4Heart diseases

1.4.1Coronary artery disease (CAD)

1.4.2Myocardial infraction (MI)

1.4.3High blood pressure or hypertension (HBP)

1.4.4Heart valve disease

1.4.5Cardiomyopathy or heart muscle disease

1.4.6Pericarditis

1.4.7Rheumatic heart disease (RHD)

1.5Mitral valve diseases

1.5.1Mitral regurgitation (MR)

1.5.2Causes of mitral regurgitation

1.5.3Mitral regurgitation signs and symptoms

1.5.4Mitral regurgitation diagnosis

1.6Cardiac disease diagnosis methods

1.6.1Principles of echo

1.6.2Modes of echocardiography

1.6.3Two-dimensional recording techniques

1.6.4Advantages and limitations of echocardiography

1.7Results and analysis

1.8Discussion

1.9Conclusions

References

1.1: Introduction

The heart is a muscular structure and a central component of the vertebrate cardiovascular system. The heart functions in a closed loop manner, that is, oxygenated blood is pumped from the lungs to the whole body and deoxygenated blood is pumped back from the lungs to the body. The transfer of blood from heart to the body is carried out by the arteries and arterioles, while the returning of the blood is done through the venules and veins. Blood transport is vital to bring oxygen and nutrients to the body’s tissues as well as to remove carbon dioxide and waste products/chemicals [1].

The human heart is located between the lungs. Because of slight tilting of its apex on the left side of the chest, heart rhythm or beating occurs in this location causing an illusion that the heart is located on that side. The size of a human heart is that of a tightly closed fist. It beats about 100,000 times in a day.

Although the heart pumps blood, delivering oxygen to the entire body’s muscles and organs for them to function, it also needs its own oxygen-enriched blood to work properly. The heart functions as a large muscular pump with arteries, veins, and valves, and an electrical system. The electrical system triggers pulse, thereby stimulating the heart to beat. The heart muscles then squeeze the blood to push the oxygenated blood throughout the entire body in one large arterial circuital system and the deoxygenated blood through the pulmonary arteries to the lungs. The two, one-way valves create separation between the four different chambers, namely, the left ventricle (LV) and left atrium (LA), and right ventricle (RV) and right atrium (RA), for forming the dual pumps of the heart adjusting both rate and flow of the oxygenated and deoxygenated blood throughout each cardiac cycle or heartbeat. The more activity a person performs, the more the heart muscles must work to supply the necessary quantity of blood to the muscles to be utilized during the activity.

Mitral regurgitation (MR) is a mitral valve insufficiency that causes a change in the size and/or shape of the LV, affecting its functioning and resulting from ischemic heart disease [2, 3]. MR leads to myocardial infarction (MI) in about 20% of cases [4, 5]. The severity of MR increases around 30% in patients suffering from coronary artery disease (CAD) with ischemic LV dysfunction [6].

There are many approaches available to diagnose MR that are helpful in determining severity grade and dysfunction [7–13]. Diagnostic methods include assessment of regurgitation volume, orifice size, orifice, and regurgitant orifice with the help of echocardiography or catheterization. In addition, two-dimensional (2D) contrast echocardiography and Doppler echocardiography are efficient ways for assessing MR. We discuss the advantages of these techniques later in the chapter [14–20].

To begin, this chapter discusses different heart conditions by categorizing heart valves and their related diseases, with a special focus on MR. It also presents various diagnostic methods and the qualitative and quantitative parameters useful in grading MR severity. Finally, the chapter ends with a discussion of different modes and techniques of echocardiography.

1.2: Heart valves

The two atrioventricular (AV), one-way valves are thin structures, having connective tissues and endocardia. These valves, namely, the bicuspid/mitral and the tricuspid AV valves are located between the LA and the LV, and the RA and RV, respectively. The two semilunar, one-way valves are made up of three flaps, each composed of connective tissues and endocardium as well as fibers to prevent the valves from flapping inside out. Their shapes are like a half moon and thus they are called the semilunar (SL) aortic valve and SL pulmonary valve. These valves are located between the left ventricle and aorta and between the RV and the start of pulmonary artery. Fig. 1.1 shows these valves. The heart’s one-way blood flow is maintained with the help of four heart valves, each one having a specific position on the exits of the four chambers. These four heart valves allow only the one-way flow of blood in the forward directions and restrict the backward flow of blood. Sequence of blood flow is from the atria (right and left) into the ventricles (right and left) through the open tricuspid and mitral valves, respectively, as shown in Fig. 1.1. According to pressure change in the chambers, there is an opening or closing of AV valves. They close during the ventricular systole (contraction) when the ventricle pressure increases the pressure in the two atria. This action keeps the valves snapped shut and prevents backward flow of blood. The contraction of the ventricles leads to forced opening of the pulmonary and aortic valves to pump the blood from the right and left ventricles into the pulmonary artery (through open valves) towards the lungs, and through the aortic valve to the aorta and the body. At the end of contraction, the ventricles begin to relax and the aortic and pulmonic valves remain closed during the diastole. Backward flow of blood into the ventricles is prevented by these valves. This pattern repeats again and again, causing continuous blood flow from the heart to the lungs and the body.

Fig. 1.1

Fig. 1.1 Classification of heart valves.

1.3: Mitral valve regurgitation

To visualize the mitral valve (MV), clinicians must choose a technique that enhances the image according to their visual perception and that works in accordance with the kind of image [21]. Log transformation does not give satisfactory results (subjective assessment) in the contrast enhancement of echocardiographic images due to high white pixel spreading. This white spreading overlaps the important features. The reason for this problem is that more pixels will shift in the high-intensity value when the log transformation is applied. To overcome this problem, the figure of 1 in Eq. (1.1) of log transformation is replaced by a variable, say, a. This offers a flexible way to analyze the image at different values of a. This value can be changed by clinicians in accordance with their visual perceptions for better visualization of the image. The normal MV opens when the LV relaxes (diastole) to allow blood flow from the LA and to fill the LV (decompressed).

During systole or contraction of the LV, the pressure in the LV increases. This increased pressure leads to closure of the MV and restricts blood flow from leaking into the LA. At this time, the blood flows to the aorta (passing the aortic valve) and the body. The annulus, leaflets, and subvalvular apparatuses work in a complex manner for the proper functioning of the valve. The mitral leaflet tissues are organized in three layers: fibrosa, spongiosa, and ventricularis. Table 1.1 [23, 24] describes the location, composition, and functions of these layers.

Table 1.1

1.4: Heart diseases

Heart diseases are abnormalities that affect the valves, functions, electrical system, muscles, and arteries of the heart. Some common heart diseases include:

•Coronary artery disease (CAD)

•Myocardial infarction (MI)—a severe type of heart disease

•High blood pressure or hypertension (HBP)

•Heart valve disease

•Cardiomyopathy or heart muscle disease

•Pericarditis

•Rheumatic heart disease (RHD)

1.4.1: Coronary artery disease (CAD)

CAD is a disease in which a deposit called plaque grows on the inside wells of the coronary arteries and restricts the normal oxygenated blood supply to heart muscles. It is almost often due to the progressive buildup of cholesterol and other fatty materials, known as atherosclerotic plaque or atheroma, in the walls of the coronary arteries. This process is known as atherosclerosis and can affect many arteries, not just those of the heart. As an atheroma develops, it may gush into the artery, narrowing the artery’s interior (lumen) and partially blocking blood flow. Calcium accumulates inside the atheroma over time. The supply of oxygen-rich blood to the heart muscle (myocardium) becomes inadequate when an atheroma blocks more and more of a coronary artery. To encourage good health, it is recommended to reduce dietary fat intake to no more than 25–35% of daily calories. However, some doctors believe that to minimize the risk of coronary heart disease, fat must be reduced to 10% of daily calories. Another way to mitigate risk factors for CAD is to consume a low-fat diet that also tends to lower elevated total and LDL (bad) cholesterol