Disorders of Circulatory System

The circulatory system is a marvel of biological engineering, responsible for the continuous transport of oxygen, nutrients, hormones, and waste products throughout the body. Its proper functioning is critical for maintaining cellular life and overall homeostasis.

When this intricate system is compromised, a range of disorders can arise, collectively known as circulatory system disorders. These conditions are a major focus in medical science due to their prevalence and significant impact on human health.

For NEET aspirants, a clear understanding of their causes, symptoms, and physiological basis is essential.

I. Hypertension (High Blood Pressure)

Hypertension is a chronic medical condition in which the blood pressure in the arteries is persistently elevated. Blood pressure is the force exerted by circulating blood against the walls of the body's arteries, the major blood vessels. It is expressed as two numbers: systolic pressure (the pressure when the heart beats) over diastolic pressure (the pressure when the heart rests between beats). Normal blood pressure is typically around $120/80\,\text{mmHg}$.

Classification of Blood Pressure (Adults):

Normal: — $<120\,\text{mmHg}$ systolic AND $<80\,\text{mmHg}$ diastolic
Elevated (Pre-hypertension): — $120-129\,\text{mmHg}$ systolic AND $<80\,\text{mmHg}$ diastolic
Hypertension Stage 1: — $130-139\,\text{mmHg}$ systolic OR $80-89\,\text{mmHg}$ diastolic
Hypertension Stage 2: — $\ge 140\,\text{mmHg}$ systolic OR $\ge 90\,\text{mmHg}$ diastolic
Hypertensive Crisis: — $>180\,\text{mmHg}$ systolic AND/OR $>120\,\text{mmHg}$ diastolic

Types of Hypertension:

1
Primary (Essential) Hypertension: — Accounts for 90-95% of cases. It has no identifiable cause and is thought to develop gradually over many years due to a combination of genetic predisposition and lifestyle factors (e.g., high salt intake, obesity, lack of exercise, stress, smoking, excessive alcohol consumption).
2
Secondary Hypertension: — Caused by an underlying condition, such as kidney disease, adrenal gland tumors, thyroid problems, or certain medications. It often appears suddenly and causes higher blood pressure than primary hypertension.

Symptoms and Complications: Hypertension is often called the 'silent killer' because it usually has no obvious symptoms until it has caused significant damage. Untreated hypertension can lead to severe complications, including heart attack, stroke, heart failure, kidney disease, vision loss, and peripheral artery disease.

II. Coronary Artery Disease (CAD)

Coronary Artery Disease (CAD) is the most common type of heart disease, caused by plaque buildup in the walls of the arteries that supply blood to the heart (coronary arteries). This plaque buildup, a process called atherosclerosis, narrows the arteries, reducing blood flow to the heart muscle. When the heart muscle doesn't receive enough oxygen-rich blood, it can lead to various problems.

Atherosclerosis: This is a progressive disease characterized by the hardening and narrowing of arteries due to the accumulation of fatty deposits (plaque) on their inner walls. The plaque is composed of cholesterol, fatty substances, cellular waste products, calcium, and fibrin. Over time, these plaques can grow, harden, and sometimes rupture, leading to blood clot formation that can further block the artery.

Risk Factors for CAD: Similar to hypertension, these include high cholesterol, high blood pressure, diabetes, smoking, obesity, physical inactivity, unhealthy diet, age, and family history.

Manifestations of CAD:

1
Angina Pectoris: — This is chest pain or discomfort caused by reduced blood flow to the heart muscle (myocardial ischemia). It's a symptom of CAD, not a disease itself. Angina typically feels like squeezing, pressure, heaviness, tightness, or pain in the chest. It can radiate to the arms, neck, jaw, back, or stomach. It often occurs during physical exertion or emotional stress and subsides with rest or medication (like nitroglycerin).

* Stable Angina: Predictable, occurs with exertion, relieved by rest. * Unstable Angina: Unpredictable, occurs at rest or with minimal exertion, more severe, and indicates a higher risk of heart attack.

1
Myocardial Infarction (MI) / Heart Attack: — Occurs when blood flow to a part of the heart muscle is severely reduced or completely blocked, usually by a blood clot forming on a ruptured atherosclerotic plaque. Without oxygen, the heart muscle cells begin to die. This is a medical emergency. Symptoms include severe chest pain (often crushing or squeezing), shortness of breath, sweating, nausea, and pain radiating to the left arm, jaw, or back. Prompt medical intervention is crucial to restore blood flow and minimize heart muscle damage.

III. Heart Failure (Congestive Heart Failure - CHF)

Heart failure is a chronic, progressive condition in which the heart muscle is unable to pump enough blood to meet the body's needs for blood and oxygen. It does not mean the heart has stopped beating, but rather that it is failing to pump efficiently. This can happen if the heart muscle becomes too weak (systolic heart failure) or too stiff (diastolic heart failure) to fill properly.

Causes: Heart failure often develops after other conditions have damaged or weakened the heart, such as CAD, high blood pressure, previous heart attacks, diabetes, certain arrhythmias, and valvular heart disease.

Types of Heart Failure:

1
Left-sided Heart Failure: — The left ventricle, responsible for pumping blood to the body, is affected. Blood backs up into the lungs, causing symptoms like shortness of breath (dyspnea), especially when lying down (orthopnea), and coughing.
2
Right-sided Heart Failure: — The right ventricle, responsible for pumping blood to the lungs, is affected. Blood backs up into the body's veins, leading to swelling (edema) in the legs, ankles, and abdomen (ascites), and jugular venous distension.
3
Congestive Heart Failure (CHF): — This term is often used when fluid buildup (congestion) occurs in the lungs, liver, abdomen, and lower extremities due to the heart's inability to pump effectively. It can involve both left and right sides.

Symptoms: Shortness of breath, fatigue, weakness, swelling in legs/ankles/feet, rapid or irregular heartbeat, persistent cough or wheezing with white or pink blood-tinged phlegm, increased need to urinate at night, abdominal swelling, rapid weight gain from fluid retention.

IV. Other Important Circulatory Disorders

Cardiac Arrest: — This is an abrupt loss of heart function, breathing, and consciousness. It's caused by an electrical disturbance in the heart that disrupts its pumping action, stopping blood flow to the brain and other organs. It is distinct from a heart attack, though a heart attack can sometimes trigger cardiac arrest.
Stroke: — Occurs when the blood supply to part of your brain is interrupted or reduced, depriving brain tissue of oxygen and nutrients. Brain cells begin to die within minutes. Strokes are primarily of two types: ischemic (due to a clot blocking a blood vessel in the brain) and hemorrhagic (due to a blood vessel rupturing and bleeding into the brain). While primarily a neurological event, its root cause is often a circulatory problem.
Arrhythmias: — Irregular heartbeats, where the heart beats too fast (tachycardia), too slow (bradycardia), or with an irregular rhythm. These can range from harmless to life-threatening, depending on the underlying cause and severity.
Peripheral Artery Disease (PAD): — A circulatory condition in which narrowed arteries reduce blood flow to the limbs, most commonly the legs. This is also caused by atherosclerosis and can lead to pain, numbness, or cramping in the affected limbs, especially during exercise.

Common Misconceptions & NEET-Specific Angle

It is crucial for NEET aspirants to clearly differentiate between a heart attack, heart failure, and cardiac arrest:

Heart Attack (Myocardial Infarction): — A 'plumbing problem' – a blockage in a coronary artery leading to heart muscle death. The heart is still beating, but part of it is damaged.
Heart Failure: — A 'pumping problem' – the heart is too weak or stiff to pump blood effectively. It's still beating, but inefficiently.
Cardiac Arrest: — An 'electrical problem' – the heart's electrical activity becomes chaotic, causing it to stop beating effectively and suddenly. This is an immediate life-threatening emergency.

NEET questions often focus on identifying the primary cause of a disorder (e.g., atherosclerosis for CAD), recognizing key symptoms, understanding the normal range of physiological parameters (e.g., blood pressure), and distinguishing between similar-sounding conditions. Emphasis is also placed on risk factors and preventive measures.