The term Clinical Cardiology refers to the comprehensive management of patients being investigated or treated for heart diseases. The most common symptoms that prompt patients to consult a physician include chest, neck, or left arm pain during physical exertion (angina), shortness of breath during exertion or at rest (left ventricular or valvular dysfunction), ankle swelling (right ventricular or valvular dysfunction), and palpitations (arrhythmias). The term myocardial infarction refers to the acute occlusion of a coronary artery. Sudden cardiac death is caused by tachyarrhythmias or asystole in cases of heart failure. These arrhythmias may result from myocardial infarction or electrical disturbances of the heart. Impaired function of the left or right ventricular myocardium is responsible for the development of heart failure.
The cause of angina is coronary artery disease (CAD), which occurs when the heart’s blood vessels – the coronary arteries – become narrowed or blocked, resulting in reduced blood supply to the heart. The pathophysiology of CAD involves a complex interaction of lipid metabolism and lipid deposition, endothelial dysfunction, and inflammatory processes. Endothelial injury or dysfunction caused by risk factors allows LDL cholesterol to infiltrate the arterial wall. Subsequent oxidation of LDL cholesterol attracts inflammatory cells, resulting in the formation of atherosclerotic plaques. Over time, these plaques grow, potentially causing partial or complete blockage of the coronary arteries, compromising the blood flow to the heart.
Multiple risk factors contribute to the development and progression of CAD, including modifiable factors such as smoking, hypertension, dyslipidemia (elevated cholesterol levels), diabetes mellitus (high blood sugar), obesity, sedentary lifestyle, and unhealthy diet. Myocardial infarction occurs when blood flow to a portion of the myocardium is abruptly interrupted, leading to necrosis of cardiac cells. This is usually caused by occlusion of one or more coronary arteries. The most common cause of myocardial infarction is rupture of an atherosclerotic plaque in a coronary artery, which may trigger thrombus formation, leading to complete arterial occlusion and myocardial tissue necrosis, potentially impairing cardiac function.
Heart failure is characterised by the heart’s inability to receive blood from the venous system, pump it to the lungs, and subsequently propel it into the arterial circulation. This incapacity results in insufficient delivery of oxygen and nutrients to organs and tissues. It is commonly caused by underlying cardiovascular conditions such as CAD, hypertension, viral myocarditis, valvular disease, or cardiomyopathies. Heart failure manifests as exertional dyspnea, weakness, and potentially peripheral oedema. Management of chronic heart failure aims to improve symptoms, slow disease progression, and enhance the patient’s quality of life. It usually involves lifestyle modifications, pharmacotherapy, and sometimes devices or surgical interventions. In advanced cases, additional measures may include cardiac resynchronisation therapy with biventricular pacemakers, implantable cardioverter-defibrillators (ICDs) to prevent life-threatening arrhythmias, left ventricular assist devices (LVADs), or, in severe cases, heart transplantation.
The heart consists of four chambers and four valves: the aortic, mitral, tricuspid, and pulmonary valves. These valves maintain proper unidirectional blood flow through the heart to the lungs and the systemic circulation. Valvular heart diseases occur when valve function is impaired, which may result from congenital anomalies, infections, degenerative changes, or conditions such as rheumatic fever.
Cardiomyopathies are a group of diseases affecting the heart muscle (myocardium), leading to dysfunction of the left or right ventricles (and sometimes the atria). These conditions may cause structural and functional abnormalities, reducing the heart’s pumping efficiency. Cardiomyopathies are typically chronic and progressive, significantly impacting overall cardiovascular health. They may arise from genetic mutations, viral infections, certain medications or toxins, systemic diseases (e.g., diabetes, thyroid disorders), chronic hypertension, or autoimmune conditions. Diagnosis often involves a combination of patient history, physical examination, electrocardiography, echocardiography, cardiac MRI, and genetic testing.
Arrhythmias are disorders of the normal cardiac rhythm and encompass a wide spectrum of disease entities. Tachyarrhythmias occur when the heart rate exceeds 100 beats per minute, whereas bradyarrhythmias occur when the heart rate falls below 50 beats per minute. Arrhythmias range from benign to life-threatening and can originate in the atria or ventricles, classified as supraventricular or ventricular, respectively. Supraventricular arrhythmias include atrial tachycardia, atrioventricular nodal reentrant tachycardia (AVNRT), tachycardia involving an accessory pathway, and atrial flutter. Ventricular arrhythmias include premature ventricular contractions, ventricular tachycardia, and ventricular fibrillation. Ventricular fibrillation stops effective cardiac output, leading to sudden loss of consciousness and cardiac arrest. Immediate medical intervention and defibrillation are critical to restore normal rhythm and prevent sudden cardiac death. The most common arrhythmia in human is atrial fibrillation, characterized by chaotic and irregular electrical signals in the atria, resulting in multiple erratic impulses reaching the ventricles. This disorganised electrical activity can impair ventricular filling and ejection of blood, leading to stasis of blood within the atria and increased risk of thrombus formation, which can embolize to the brain and cause ischemic stroke. Other potential complications of atrial fibrillation include myocardial fatigue and heart failure. Causes of arrhythmias vary widely and may include underlying heart disease (CAD, heart failure, valvular disease, congenital anomalies, or genetic conduction disorders), hypertension, electrolyte imbalances, medications, alcohol or drug abuse, thyroid disorders, stress, and stimulants such as nicotine. Management depends on arrhythmia type, severity, and underlying cause.
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