What Do New Insights Offer On The Pathophysiology Of Heart Disease?
What Do New Insights Offer On The Pathophysiology Of Heart Disease?
Introduction
Recent advances in medical science have offered interesting insights into the pathophysiology of heart disease. This has paved the way for new treatment approaches that will deliver better outcomes. For instance, research has helped identify the mechanisms involved in atherosclerosis. Similarly, the role of peptide hormones as biomarkers have also been identified. This helps in adopting better treatment approaches for effective outcomes.
Overview Of Ischemic Heart Disease Pathogenesis
Also known as coronary artery disease this is mainly due to reduced flow of blood to the heart muscle. This deprives the heart of the required levels of oxygen and nutrients. Lets understand more about this as part of insights into pathophysiology of heart disease.
- Atherosclerosis – This typically starts with damage to the inner lining of blood vessels, as a result of hypertension, smoking, high levels of cholesterol and diabetes. Consequently, low-density lipoprotein cholesterol particles enter the walls of the vessel, triggering an inflammatory response. This causes accumulation of immune cells, such as macrophages, at the location.
- Plaque – Following the above, fatty deposits begin to buildup in the artery walls. This narrows the artery limiting flow of blood.
- Calcification – This slowly hardens and calcifies, causing the arteries to stiffen. This is essentially atherosclerosis, causing reduced flow of blood.
- Thrombosis – When the plaque ruptures, it causes formation of a blood clot that can block the artery.
The various stages may not present symptoms in the early stages. However, later on, symptoms such as angina, and difficulty breathing may be experienced.
What Is Rheumatic Heart Disease Pathogenesis?
This refers to a chronic condition due to rheumatic fever, post strep throat infections. Let’s look at the pathogenesis resulting in damaged heart tissues, as part of understanding the pathophysiology of heart disease.
- Streptococcal infection – As outlined above, the first step is a throat infection due to Group A Streptococcus bacteria. Following this, some individuals are likely to experience an immune response, where antibodies wrongly target the healthy tissues of the body.
- Rheumatic fever – When the condition affects the heart, it results in rheumatic fever. In this condition, the entire heart ends up inflamed.
- Damage to the Valve – The inflammation targets the heart valves, such as the mitral valve, or the aortic valve. This causes scarring and thickening of the valve leaflets, causing structural or functional deformities of the valve. This condition develops over many years and can cause heart failure when left untreated.
What Does Pathology Of Rheumatic Heart Disease Mean?
This refers to the actual structural and other changes in the heart due to RHD. Let us understand more about effects on the heart tissues, as part of our understanding of pathophysiology of heart disease.
- Damage to heart valve – The most commonly affected valve is the mitral valve. The nature of damage includes thickening, scarring, and fusion causing narrowing or leakage.
- Aschoff bodies – Refer to inflammatory lesions in the heart muscle of people afflicted with rheumatic fever.
- Pancarditis – Refers to condition that causes inflammation of multiple layers of the heart, such as the inner layer, the heart muscle and outer layer.
- Fibrosis – Due to repeated inflammation formation of scar tissue occurs in the valves. This calcifies making the valves rigid, causing abnormal functioning.
Explanation Of Ischemic Heart Disease Pathophysiology Flow Chart
As part of understanding of pathophysiology of heart disease, lets look at the sequence of pathophysiology of ischemic heart disease.
Risk Factors >> Injury to inner artery lining >> Deposit of lipids >> Formation of plaque >> Narrowing of artery restricting flow of blood >> Limited supply of oxygen to heart >> Rupture of plaque >> Formation of clot >> Blockage of artery >> Heart attack or chest pain >> Heart failure, arrhythmias.
Explanation of above sequence
Risk factors – Include high cholesterol, hypertension, smoking, diabetes, and obesity.
Injury to endothelium – This damage triggers the condition.
Lipid deposit – Following the damage, low-density lipoprotein cholesterol particles enter the artery wall, and accumulate.
Plaque – Tis triggers in formation of plaque, narrowing the artery over time.
Ischemia – Due to reduced flow of blood to the heart muscle, ischemia occurs. This is essentially lack of oxygen in the tissues, causing chest pain.
Rupture – Unstable plaque ruptures, releasing the contents to the bloodstream.
Clot formation – When plaque ruptures, it causes formation of a blood clot that can block the artery.
Blockage – A partial or complete blockage of the artery may result in abrupt and severe reduction in blood flow.
Myocardial infarction – A heart attack occurs due to complete blockage, due to damage to the heart tissue. Angina occurs due to partial blockage.
Meaning Of Congenital Heart Disease Pathophysiology
The above understanding of the pathophysiology of heart disease will be incomplete without learning about congenital heart diseases. This refers to structural abnormalities in the heart or blood vessels from birth. This is due to genetic, environmental, or other factors that impact heart development during fetal growth. Let us look at the different stages.
- Heart development – Genetic mutations, illnesses such as rubella, or other like medications or alcohol consumption disrupts normal heart development.
- Abnormalities – Could include holes between chambers, permitting blood to mix between the left and right sides. This results in the mixing of oxygenated and deoxygenated blood.
- Defects – Due to structural abnormalities, blood flow is restricted, causing increased workload on the heart. Other defects cause cyanosis, resulting in a bluish appearance.
Advanced genetic testing facilities presently available in Tamilnadu, help in determining the presence of congenital or inherited heart diseases. The tests help to either confirm or rule out the presence of the conditions. Samples of blood or saliva are al that are required for the tests. A detailed analysis and interpretation of the analysis helps cardiologists to determine the conditions. Based on the test results, appropriate treatment and lifestyle changes will then be recommended.
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Shetty B s a cardiologist in Chennai, with extensive experience in the field. He completed his MBBS from Madurai Kamaraj University, followed by an MD in General Medicine and a DM in Cardiology from The Tamil Nadu Dr. M.G.R. Medical University (TNMGRMU).