” 7 different types of heart diseases.”

HEART DISEASE

” Heart disease” describes several heart conditions significantly affecting heart vessels. This is a broad term that covers many heart-related problems and needs. It includes –

1- CARDIAC FAILURE

2- DISORDERS OF HEART VALVES

3- ISCHEMIC HEART DISEASE

4- RHEUMATIC HEART DISEASE

5- INFECTIVE ENDOCARDITIS

6- CARDIAC ARRHYTHMIAS

7- CONGENITAL ABNORMALITIES

CARDIAC FAILURE / HEART FAILURE

Heart disease is a failure when the cardiac output cannot maintain sufficient blood circulation to meet the body’s needs. In mild cases, cardiac output is adequate at rest and becomes inadequate only when increased cardiac output is required ex. in exercise. Heart failure may affect either side of the heart, but since both sides of the heart are part of one circuit when one-half of the pump begins to fail it frequently leads to increased strain on, and eventual failure of, the other side.

The main clinical manifestations depend on which side of the heart is most affected. Because the left ventricle has a more significant workload, left ventricular failure is more common than proper heart failure.

1-COMPENSATORY MECHANISMS IN HEART FAILURE

When cardiac failure happens acutely, the body has little time to make compensatory changes. However, if the heart fails over time, the following changes will likely occur to maintain cardiac output and tissue perfusion, especially of vital organs.

• The cardiac muscle fibers enlarge and increase in number, making the chambers’ walls thicker.
• The heart chambers dilate.
• Decreased renal blood flow activates the renin-angiotensin-aldosterone system, which leads to salt and water retention. This increases blood volume and cardiac workload. The direct vasoconstrictor action of angiotensin II increases peripheral resistance and puts other strain on the failing heart.

2–ACUTE CARDIAC FAILURE

A sudden decrease in blood output from both ventricles causes an acute reduction in the oxygen supply to all the tissues. Recovery from the acute phase may be followed by chronic failure, or death may occur due to anoxia of vital centers in the brain. The most typical causes are:-

• A sudden interruption of the blood supply to the myocardium may cause ischemia or tissue death. A sudden blockage of blood flow to the heart muscle can lead to tissue damage or death, known as ischemia. A sudden blockage of blood flow to the heart muscle can lead to tissue damage or death, known as ischemia.
• Pulmonary embolism blocks blood flow through the pulmonary circulation- the heart fails because it has to pump against this obstruction.
• Severe cardiac arrhythmia, when the pumping action of the heart is badly impaired or effectively spotted earnestly increases the cardiac effort required to maintain adequate output.
• Severe malignant hypertension, which significantly increases resistance to blood flow.

3- CHRONIC FAILURE

This developed gradually and in the early stages, there may be no symptoms because compensatory changes occur as described above. When further compensation is not possible, myocardial efficiency is gradually declining. Underlying causes include degenerative heart changes with advancing age and many chronic conditions, ex-anemia, lung disease, hypertension, or cardiac disease.

4- RIGHT-SIDED ( CONGESTIVE ) FAILURE

The right ventricle fails when the pressure developed by the contracting myocardium is less than the force needed to push blood through the lungs.

When compensation has reached its principle, and the ventricle is not emptying, the right atrium and venae cavae are congested with blood, followed by congestion throughout the venous system. The organs affected first are the liver, spleen, and kidneys. Edema of the limbs and ascites ( excess fluid in the peritoneal cavity ) usually follows.

Heart disease may be caused by increased vascular resistance in the lungs, weakness of the myocardium, stenosis, and incompetence of values in the heart or great vessels.

5- RESISTANCE TO BLOOD FLOW THROUGH THE LUNGS

When this is enhanced the right ventricle has more work to do. It may be caused by the following:

• The formation of fibrous tissue following inflammation or chronic disease of the lungs.
• The back pressure of the blood through the pulmonary circulation from the left side of the heart, ex-in left ventricular failure when the mitral valve is stenosed and incompetent.

6- WEAKNESS OF THE MYOCARDIUM

This may be caused by ischemia following numerous small myocardial infarcts.

7- LEFT-SIDED ( LEFT VENTRICULAR ) FAILURE

This occurs when the pressure developed in the left ventricle by the contracting myocardium is less than the pressure in the aorta and the ventricle can not then pump out all the blood it receives. Causes include ischemic heart disease, which reduces the efficiency of the myocardium, and hypertension when the heart’s workload is increased because of raised systemic resistance. The condition of the mitral and valves may prevent the efficient emptying of the heart chambers so that the myocardial workload is increased.

Failure of the left ventricle leads to dilatation of the atrium and increased pulmonary blood pressure. This is followed by high blood pressure on the right side of the heart and systemic venous congestion.

Congestion in the lungs leads to pulmonary edema and dyspnoea, often severe at night. This paroxysmal nocturnal dyspnoea may be due to raised blood volume as fluid from peripheral edema is reabsorbed when the patient slips in bed during sleep.

DISORDERS OF THE HEART VALVES https://www.mayoclinic.org/diseases-conditions/heart-disease/symptoms-causes/syc-20353118#:~:text=the%20heart%20muscle-,Heart%20valve%20disease,-Many%20forms%20of

The heart valves prevent the backflow of blood in the heart during the cardiac cycle. The left atrioventricular and aortic valves are subject to more prominent pressures than those on the right side and are thus more susceptible to damage.

Distinctive heart sounds arise when the valves close during the cardiac cycle. Damaged valves generate abnormal heart sounds called murmurs. A severe valve disorder causes heart failure. The most common causes of valve defects are rheumatic fever, fibrosis following inflammation, and congenital abnormalities.

STENOSIS

This is the narrowing of a valve opening, impeding blood flow via the valve. It occurs when inflammation and encrustations roughen the edges of the cusps so that they stick together, narrowing the valve opening.

INCOMPETENCE

Sometimes called regurgitation, this is a functional defect caused by the failure of a valve to close completely, allowing blood to flow back into the ventricle when it relaxes.

ISCHEMIC HEART DISEASE ATHEROMA: causes, effects, and complications.

Ischaemia is due to the effects of atheroma, causing narrowing or occlusion of one or more branches of the coronary arteries. Occlusion may be by plaques alone or plaques complicated by thrombosis. The overall effect depends on the size of the coronary artery entangled and whether it is only narrowed or completely blocked. Narrowing of a lane leads to angina pectoris and occlusion to the myocardial infarction.

ANGINA PECTORIS

This is sometimes called angina of effort because the increased cardiac output required during extra physical effort causes severe chest pain, which may also radiate to the arms, neck, and jaw. Other factors that may precipitate angina include cold weather and emotional states.

A narrowed coronary artery may supply sufficient blood to the myocardium to meet its needs during rest or moderate exercise but not when significantly increased cardiac output is needed, walking may be tolerated but not running. The thick, inflexible atheromatous artery wall cannot dilate to allow for the increased blood flow required by the more active myocardium, which becomes ischemic. In the early stages of angina, the chest pain stops when the cardiac output returns to its resting level soon after the extra effort stops.

MYOCARDIAL INFARCTION

The myocardium may infract when a branch of a coronary artery is occluded. The most shared cause is an atheromatous plaque complicated by thrombosis. The extent of myocardial damage depends on the blood vessel’s size and the infarct’s site. The damage is permanent because the cardiac muscle can not regenerate, and the dead potencies are replaced with non-functional fibrous tissue. Speedy restoration of blood flow through the blocked artery using clot-dissolving ( thrombolytic ) drugs can enormously reduce the extent of the permanent damage and improve prognosis. Still, treatment must be started within a few hours of the infraction. The effects and complications are the greatest when the left ventricle is involved.

The myocardial infarction is usually accompanied by undoubtedly severe crushing chest pain behind the sternum which, unlike angina pectoris, continues even when the individual is at rest.

COMPLICATIONS

These may be fatal and include:-

• Severe arrhythmias, specifically ventricular fibrillation due to disruption of the cardiac conducting system.
• Cardiac failure is caused by impaired contraction of the damaged myocardium and, in severe cases, cardiogenic shock.
• Rapture of a ventricle wall, usually within 2 weeks of the original episode.
• Pulmonary or cerebral embolism is initiated from a mural clot within a ventricle, ex- a clot that forms inside the heart over the infarct.
• Pericarditis
• Angina

RHEUMATIC HEART DISEASE UNDERSTANDING OF THE RHEUMATIC HEART DISEASE

Rheumatic fever is an inflammatory illness that sometimes follows streptococcal throat infections, most commonly in children and young adults. It is an auto-immune disorder; the antibodies produced to combat the unblemished infection damage connective tissues, including the heart, joints, and skin.

Death rarely occurs in the acute phase, but after recovery, there may be persistent damage to the heart valves, eventually leading to disability and possibly cardiac failure.

INFECTIVE ENDOCARDITIS

Pathogenic organisms ( usually bacteria or fungi ) in the blood may colonize any part of the endocardium. Still, the most common sites are on or near the heart valves and around the margins of congenital heart defects.

The main predisposing factors are-

• Bacteremia
• Depressed immune response
• Heart abnormalities

CARDIAC ARRHYTHMIAS

The heart rate is usually determined by intrinsic impulses generated in the SA node. The route of impulse transmission determines the rhythm through the conducting system. The heart rate is usually measured as the pulse, but to determine the rhythm, an electrocardiogram (ECG) is required. A cardiac arrhythmia is any disorder of heart rate or rhythm resulting from an abnormal generation or conduction of impulses.

CONGENITAL ABNORMALITIES

Abnormalities in the heart and great vessels at birth may be due to intrauterine developmental errors or to the failure of the heart and blood vessels to adapt to extrauterine life. Sometimes, there are no symptoms in early life and the abnormality is recognized only when complications appear.

References

Ross and Wilson, anatomy and Physiology in Health and Illness, Anne Waugh. Allison Grant ( Tenth edition )