Cardiology

Cardiology at Chandan Hospital includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heartdisease and electrophysiology.

The heart :

The primary responsibility of the heart is to pump blood throughout the body. It pumps blood from the body — called the systemic circulation — through the lungs — called the pulmonary circulation — and then back out to the body. The heart is a muscle that squeezes blood and functions like a pump. Each part of the heart is susceptible to failure or dysfunction and the heart can be divided into the mechanical and the electrical parts.

The electrical part of the heart is centered on the periodic contraction (squeezing) of the muscle cells that is caused by the cardiac pacemaker located in the sinoatrial node. The action potentials generated in the pacemaker propagate throughout the heart in a specific pattern. Dysfunction of the electrical system manifests in many ways and may include Wolff–Parkinson–White syndrome, ventricular fibrillation, and heart block.

The mechanical part of the heart is centered on the fluidic movement of blood and the functionality of the heart as a pump. The mechanical part is ultimately the purpose of the heart and many of the disorders of the heart disrupt the ability to move blood. Failure to move sufficient blood can result in failure in other organs and may result in death if severe. Heart failure is one condition in which the mechanical properties of the heart have failed or are failing, which means insufficient blood is being circulated.

Coronary circulation is the circulation of blood in the blood vessels of the heart muscle (myocardium). The vessels that deliver oxygen-rich blood to the myocardium are known as coronary arteries. The vessels that remove the deoxygenated blood from the heart muscle are known as cardiac veins. These include the great cardiac vein, the middle cardiac vein, the small cardiac vein and the anterior cardiac veins.

As the left and right coronary arteries run on the surface of the heart, they can be called epicardial coronary arteries. These relatively narrow vessels are commonly affected by atherosclerosis and can become blocked, causing angina or a heart attack.

Heart disorders:

Hypertension:

Diagram illustrating the main complications of persistent high blood pressure

Hypertension, also known as "high blood pressure"", is a long term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long term high blood pressure, however, is a major risk factor for coronary artery disease, stroke, heart failure, peripheral vascular disease, vision loss, and chronic kidney disease. Lifestyle factors can increase the risk of hypertension. These include excess salt in the diet, excess body weight, smoking, and alcohol. Hypertension can also be caused by other diseases, or as a side-effect of drugs.

Blood pressure is expressed by two measurements, the systolic and diastolic pressures, which are the maximum and minimum pressures, respectively. Normal blood pressure at rest is within the range of 100–140 millimeters mercury (mmHg) systolic and 60–90 mmHg diastolic. High blood pressure is present if the resting blood pressure is persistently at or above 140/90 mmHg for most adults. Different numbers apply to children. Ambulatory blood pressure monitoring over a 24-hour period appears more accurate than office best blood pressure measurement.

Essential hypertension is the form of hypertension that by definition has no identifiable cause. It is the most common type of hypertension, affecting 95% of hypertensive patients, it tends to be familial and is likely to be the consequence of an interaction between environmental and genetic factors. Prevalence of essential hypertension increases with age, and individuals with relatively high blood pressure at younger ages are at increased risk for the subsequent development of hypertension. Hypertension can increase the risk of cerebral, cardiac, and renal events.

Secondary hypertension is a type of hypertension which is caused by an identifiable underlying secondary cause. It is much less common than essential hypertension, affecting only 5% of hypertensive patients. It has many different causes including endocrine diseases, kidney diseases, and tumors. It also can be a side effect of many medications.

Complications of hypertension are clinical outcomes that result from persistent elevation of blood pressure. Hypertension is a risk factor for all clinical manifestations of atherosclerosis since it is a risk factor for atherosclerosis itself. It is an independent predisposing factor for heart failure, coronary artery disease, stroke, renal disease, and peripheral arterial disease. It is the most important risk factor for cardiovascular morbidity and mortality, in industrialized countries.

Cardiac arrhythmia, also known as "cardiac dysrhythmia" or "irregular heartbeat", is a group of conditions in which the heartbeat is irregular, too fast, or too slow. A heart rate that is too fast – above 100 beats per minute in adults – is called tachycardia and a heart rate that is too slow – below 60 beats per minute – is called bradycardia. Many types of arrhythmia have no symptoms. When symptoms are present these may include palpitations or feeling a pause between heartbeats. More seriously there may be lightheadedness, passing out, shortness of breath, or chest pain. While most types of arrhythmia are not serious, some predispose a person to complications such as stroke or heart failure. Others may result in cardiac arrest.

There are four main types of arrhythmia: extra beats, supraventricular tachycardias, ventricular arrhythmias, and bradyarrhythmias. Extra beats include premature atrial contractions, premature ventricular contractions, and premature junctional contractions. Supraventricular tachycardias include atrial fibrillation, atrial flutter, and paroxysmal supraventricular tachycardia. Ventricular arrhythmias include ventricular fibrillation and ventricular tachycardia. Arrhythmias are due to problems with the electrical conduction system of the heart. Arrhythmias may occur in children; however, the normal range for the heart rate is different and depends on age. A number of tests can help with diagnosis including an electrocardiogram (ECG) and Holter monitor.

Most arrhythmias can be effectively treated. Treatments may include medications, medical procedures such as a pacemaker, and surgery. Medications for a fast heart rate may include beta blockers or agents that attempt to restore a normal heart rhythm such as procainamide. This later group may have more significant side effects especially if taken for a long period of time. Pacemakers are often used for slow heart rates. Those with an irregular heartbeat are often treated with blood thinners to reduce the risk of complications. Those who have severe symptoms from an arrhythmia may receive urgent treatment with a jolt of electricity in the form of cardioversion or defibrillation.

Coronary artery disease, also known as "ischemic heart disease", is a group of diseases that includes: stable angina, unstable angina, myocardial infarction, and sudden cardiac death. It is within the group of cardiovascular diseases of which it is the most common type. A common symptom is chest pain or discomfort which may travel into the shoulder, arm, back, neck, or jaw. Occasionally it may feel like heartburn. Usually symptoms occur with exercise or emotional stress, last less than a few minutes, and get better with rest. Shortness of breath may also occur and sometimes no symptoms are present. The first sign is occasionally a heart attack. Other complications include heart failure or an irregular heartbeat.

Risk factors include: high blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol, poor diet, and excessive alcohol, among others. Other risks include depression. The underlying mechanism involves atherosclerosis of the arteries of the heart. A number of tests may help with diagnoses including: electrocardiogram, cardiac stress testing, coronary computed tomographic angiography, and coronary angiogram, among others.

Prevention is by eating a healthy diet, regular exercise, maintaining a healthy weight and not smoking. Sometimes medication for diabetes, high cholesterol, or high blood pressure are also used. There is limited evidence for screening people who are at low risk and do not have symptoms. Treatment involves the same measures as prevention. Additional medications such as antiplatelets including aspirin, beta blockers, or nitroglycerin may be recommended. Procedures such as percutaneous coronary intervention (PCI) or coronary artery bypass surgery (CABG) may be used in severe disease. In those with stable CAD it is unclear if PCI or CABG in addition to the other treatments improve life expectancy or decreases heart attack risk.

Cardiac arrest is a sudden stop in effective blood flow due to the failure of the heart to contract effectively. Symptoms include loss of consciousness and abnormal or absent breathing. Some people may have chest pain, shortness of breath, or nausea before this occurs. If not treated within minutes, death usually occurs.

The most common cause of cardiac arrest is coronary artery disease. Less common causes include major blood loss, lack of oxygen, very low potassium, heart failure, and intense physical exercise. A number of inherited disorders may also increase the risk including long QT syndrome. The initial heart rhythm is most often ventricular fibrillation. The diagnosis is confirmed by finding no pulse. While a cardiac arrest may be caused by heart attack or heart failure these are not the same. Prevention includes not smoking, physical activity, and maintaining a healthy weight. Treatment for cardiac arrest is immediate cardiopulmonary resuscitation (CPR) and, if a shockable rhythm is present, defibrillation. Among those who survive targeted temperature management may improve outcomes. An implantable cardiac defibrillator may be placed to reduce the chance of death from recurrence.

A congenital heart defect, also known as a "congenital heart anomaly" or "congenital heart disease", is a problem in the structure of the heart that is present at birth. Signs and symptoms depend on the specific type of problem. Symptoms can vary from none to life-threatening. When present they may include rapid breathing, bluish skin, poor weight gain, and feeling tired. It does not cause chest pain. Most congenital heart problems do not occur with other diseases. Complications that can result from heart defects include heart failure.


Electrocardiography(ECG)

Electrocardiography (ECG or EKG) is the process of recording the electrical activity of the heart over a period of time using electrodes placed on the skin. These electrodes detect the tiny electrical changes on the skin that arise from the heart muscle's electrophysiologic pattern of depolarizing and repolarizing during each heartbeat. It is a very commonly performed cardiology test.

In a conventional 12-lead ECG, ten electrodes are placed on the patient's limbs and on the surface of the chest. The overall magnitude of the heart's electrical potential is then measured from twelve different angles ("leads") and is recorded over a period of time (usually ten seconds). In this way, the overall magnitude and direction of the heart's electrical depolarization is captured at each moment throughout the cardiac cycle. The graph of voltage versus time produced by this noninvasive medical procedure is an electrocardiogram.

During each heartbeat, a healthy heart has an orderly progression of depolarization that starts with pacemaker cells in the sinoatrial node, spreads out through the atrium, passes through the atrioventricular node down into the bundle of His and into the Purkinje fibers, spreading down and to the left throughout the ventricles. This orderly pattern of depolarization gives rise to the characteristic ECG tracing. To the trained clinician, an ECG conveys a large amount of information about the structure of the heart and the function of its electrical conduction system. [5] Among other things, an ECG can be used to measure the rate and rhythm of heartbeats, the size and position of the heart chambers, the presence of any damage to the heart's muscle cells or conduction system, the effects of cardiac drugs, and the function of implanted pacemakers.

Electrodes and leads :

The 10 electrodes in a 12-lead EKG are listed below
Electrode name Electrode placement
RA On the right arm, avoiding thick muscle.
LA In the same location where RA was placed, but on the left arm.
RA On the right leg, lower end of medial aspect of calf muscle. (Avoid bony prominences)
LL In the same location where RL was placed, but on the left leg.
V1 In the fourth intercostal space (between ribs 4 and 5) just to the right of the sternum (breastbone).
V2 In the fourth intercostal space (between ribs 4 and 5) just to the left of the sternum.
V3 Between leads V2 and V4.
V4 In the fifth intercostal space (between ribs 5 and 6) in the mid-clavicular line.
V5 Horizontally even with V4, in the left anterior axillary line.
V6 Horizontally even with V4 and V5 in the midaxillary line.
Interpretation :

Interpretation of the ECG is fundamentally about understanding the electrical conduction system of the heart. Normal conduction starts and propagates in a predictable pattern, and deviation from this pattern can be a normal variation or be pathological. An ECG does not equate with mechanical pumping activity of the heart, for example, pulseless electrical activity produces an ECG that should pump blood but no pulses are felt (and constitutes a medical emergency and CPR should be performed). Ventricular fibrillation produces an ECG but is too dysfunctional to produce a life-sustaining cardiac output. Certain rhythms are known to have good cardiac output and some are known to have bad cardiac output. Ultimately, an echocardiogram or other anatomical imaging modality is useful in assessing the mechanical function of the heart.

Like all medical tests, what constitutes "normal" is based on population studies. The heart rate range of between 60 and 100 is considered normal since data shows this to be the usual resting heart rate.

Diagnosis :

Numerous diagnosis and findings can be made based upon electrocardiography. Overall, the diagnosis/diagnoses are made based on the patterns.

Rhythm disturbances/ Arrhythmias :
  • Atrial fibrillation & atrial flutter without rapid ventricular response
  • Premature atrial contraction (PACs) & Premature ventricular contraction (PVCs)
  • Sinus arrhythmia
  • Sinus bradycardia & sinus tachycardia
  • Sinus pause & sinoatrial arrest
  • Sick sinus syndrome: bradycardia-tachycardia syndrome
  • Supraventricular tachycardia
  • Atrial fibrillation (afib) with rapid ventricular response
  • Atrial flutter with rapid ventricular response
  • AV nodal reentrant tachycardia
  • Atrioventricular reentrant tachycardia
  • Junctional ectopic tachycardia
  • Atrial tachycardia
  • Ectopic atrial tachycardia (unicentric)
  • Multifocal atrial tachycardia
  • Paroxysmal atrial tachycardia
  • Sinoatrial nodal reentrant tachycardia
  • Torsades de pointes (polymorphic ventricular tachycardia)
  • Wide complex tachycardia
  • Ventricular flutter
  • Ventricular fibrillation
  • Ventricular tachycardia (monomorphic ventricular tachycardia)
  • Pre-excitation syndrome
  • Lown–Ganong–Levine syndrome
  • Wolff–Parkinson–White syndrome
  • J wave / Osborn wave
Heart block and conduction problems :
  • Aberration
  • Sinoatrial block: first, second, and third-degree
  • AV node
  • First-degree AV block
  • Second-degree AV block (Mobitz I & II; Mobitz I aka Wenckebach)
  • Third-degree AV block / complete AV block
  • Right bundle
  • Incomplete right bundle branch block
  • Complete right bundle branch block (RBBB)
  • Left bundle
  • Complete left bundle branch block (LBBB)
  • Incomplete left bundle branch block
  • Left anterior fascicular block (LAFB)
  • Left posterior fascicular block (LPFB)
  • Bifascicular block (LAFB plus LPFB)
  • Trifascicular block (LAFP plus FPFB plus RBBB)
  • QT syndromes
  • Brugada syndrome
  • Short QT syndrome
  • Long QT syndromes, genetic and drug-induced
  • Right and left atrial abnormality
  • Electrolytes disturbances & intoxication
  • Digitalis intoxication
  • Calcium: hypocalcemia and hypercalcemia
  • Potassium hypokalemia and hyperkalemia
Ischemia and infarction :
  • Wellens' syndrome
  • ST elevation and ST depression
  • High Frequency QRS changes
  • Myocardial infarction (heart attack)
  • Non-Q wave myocardial infarction
  • NSTEMI
  • STEMI
Structural :
  • Acute pericarditis
  • Right and left ventricular hypertrophy
  • Right ventricular strain / S1Q3T3