Cardiovascular System

Structure of Heart

Size of fist, wt ½ kg

Four chambers: 2 ventricle &

Atrium, covered by pericardium

Circulation of blood

• The cardiac cycle is the sequence of events that occur when the heart beats. There are two phases of this cycle:

Diastole - Ventricles are relaxed. Hence blood flows in from vena cava and pulmonary veins, also blood flows from right & left atria into ventricles

Systole - Ventricles contract, hence the blood is pumped into the Pulmonary Artery & aorta.

The beat of the heart as felt through the walls of the artery is called the pulse, it is palpated at radial artery,neck, elbow, groin.

Heart sounds are because of the closure of the valves of heart.

Abnormal heart sound are known as “murmur”

Blood pressure: is the force it exerts on the arterial wall, measured by device called Spygmanometer.

It is expressed as a fraction e.g 120/80 mm of Hg in which 120 is the systolic pressure & 80 is the diastolic pressure

Conditions of Heart• Arrhythmia: abnormal heart rhythms

Types:

Heart Block: failure of proper conduction of impulses through the AV node to the bundle of His.

Cardiac Pacemaker: implantation can overcome the heart block.

Flutter: rapid, irregular contractions of atria or ventricles, HR reaches upto 300 beats/min., occurs in heart disease

Fibrillation: rapid, random, ineffectual & irregular contractions of heart upto 350/min, inorder to restore the normal sinus rhythm, a electrical device called DEFIBRILLATOR is applied on the chest wall, the electrical shock stops the heart and reverses its abnormal rhythm, also called as CARDIOVERSION

Cardiac arrest: sudden & often unexpected stoppage of heart movement, caused by heart block or ventricular fibrillation.

Palpitations are uncomfortable sensations in the chest associated with different types of arrhythmias.

Causes are smoking, caffeine & drugs while cardiac causes are premature ventricular contractions(PVCs) & premature atrial contractions(PACs)

• Congenital heart disease: deformities of heart at birth

Coarctation of the aorta: narrowing of the aorta, surgical treatment consist of removal of the constricted region and end to end anastomosis of segment.

Patent ductus aretriosus: a small duct between the aorta and the pulmonary artery, which closes soon after birth, remains patent, leading to transfer og oxygenated blood from aorta to PA, RX is surgery

Septal defects: small holes in the septa between the atria(atrial septal defect) or ventricle called as ventricular septal defect, these can close spontaneously.

Tetralogy of fallot: four malformations distinct defect i.e

Pulmonary artery stenosis

Ventricular septal defect

Shift of aorta to the right

Hypertrophy of the right ventricle

A infant with this condition is described as BLUE BABY, because of the extreme degree of cynosis present at birth, treated by surgery

• Congestive Heart Failure: the heart is unable to pump its required amount of blood, left sided failure leads to accumulation of fluid in lungs, while right sided causes accumulation in the abdominal organs and legs

• Coronary artery disease : these are the b.v surrounding the heart, leading the atherisclerosis, which leads to narrowing of the vessel, rupture of the artery or abnormal clotting of blood, leading to thrombotic occlusion. In these cases, blood flow is decreased, leading to death(necrosis) of a part of myocardium, the area od dead myocardial tissue is known as infarction, the area is later replaced by scar tissue.

• Angina pectoris is an episode of chest pain resulting from the temporary difference between the supply and demand of oxygen to the heart muscle

The causes of angina: low level of oxygen the blood, restricted blood supply, increase on the workload of the heart beyond normal limits

• Endocarditis: inflammation of the inner lining of the heart caused by bacteria valves produce lesions called vegetations, that may break off into the blood stream as emboli, antibiotics are effective in treating this condition

• Hypertensive Heart disease, high B.P affecting the heart, caused by contraction of the arterioles of the body leading to increased pressure in the arteries, vessels loose there elasticity & become solid like pipes

• Mitral valve prolapse, there is improper closure of the mitral valve, leading to prolapse into left atrium during systole. Midsystolic click is heard upon ausculatation

• Murmur an extra heart sound, heart between normal beats, heard with aid of a stethoscope, they are due to valvular defect or diseases that disrupts the smooth flow of blood in the heart

• Pericarditis inflammation of the membrane(pericardium) surrounding the heart due to bacteria, viral or idipathic.symptoms of malaise, fever and chest pain occurs as well as accumilation of fluid within the pericardial cavity(cardiac tamponade).fluid drained by pericardiocentesis

• Rheumatic heart disease, heart condition due to rheumatic fever, follows after few weeks of streptococcal infection, leadind to infection of valves.

Mitral stenosis, atrial fibrillation & CCF due weakining of the myocardium, treated by antiarrythmic drugs, anticoagulant therapy.

• Atrial Myxoma: tumour of the heart, surgery is the treatment.• Cor pulmonale: due to lung disease there is pressure over the heart

Blood vessels

• Aneurysm (/berry aneurysm/pseudoaneruysm);local widening of the artery caused by weakness in the arterial wall or breakdown of the wall owing to atherosclerosis. It is most common in aorta. The danger of the aneurysm is that it may eventually rupture.

• Hypertension: high pressure in the blood vessel, normal BP is 120/80.

Secondary HT is because of renal conditions, • Peripheral vascular disease: blockage of b.vs in the lower extremities

due to atherosclerosis, often femoral or popliteal artery is involved, early sign is intermittent claudications.

Treatment: exercise, avoidance of nicotine & control of risk factors such as HT, hyperlipedimia & diabetes, surgical treatment consist of endarterectomy and grafting.

• Raynaud’s phenomenon: short episodes of pallor and numbness in the fingers and toes due to temporary constriction of arterioles in the skin. It is usually idiopathic, but the episode can be triggered by cold temperature, emotional stress or cigarette smoking.Rx is vasodilators.

• Varicose veins: abnormally swollen & twisted veins, usually occurring in the legs. This is due to damaged valves that fail to prevent the backflow of blood. The blood collects in the vein, which distend to many times their normal size, leading to thrombosis.

Hemorrhoids(piles) distended veins in the anal region.• Thrombophlebitis: infection of the vein along with thrombus formation• Thrombectomy: removal of thrombus by surgery

LABORATORY TEST• Lipid profile tests:lipids are fatty substance found in foods

and in the body. Examples are cholesterol and triglycerides. Lipid test measures the amount of these substances in the blood samples. High levels are associated with greater risk of atherosclerosis.

• Lipoproteins electrophorosis: lipoproteins are proteins that carry lipids (fats) in the blood stream. Protein electrophoresis is the process of physically separating lipoproteins from a blood sample. High levels of low density lipoproteins (LDL) and very low density lipoproteins (VLDL) are associated with atherosclerosis. High levels of high density lipoproteins (HDL) protect adults from development of atherosclerosis.

• Serum enzyme test during a myocardial infarction, enzymes are released into the blood stream from the dying heart muscles. These enzymes can be measured and are useful as evidence of an infarction. The enzymes tested are creatinine phosphokinase(CPK,CK) and protein troponin(TnT).

CLINICAL PROCEDURES

• Angiography: Dye is injected into the blood stream or heart chamber and x-rays are taken of the heart and large blood vessels in the chest. If the dye is injected into the aorta or an artery in the groin, the procedure is called cardiac catheterization.

• Digital subtraction angiography:Video equipment and a computer are used to produce x-ray pictures of blood vessels. Second image is taken after injecting contrast material into a vein. Then the computer is used to substract first image from the second leaving only the structures that need to be studied.

• Doppler ultrasound:The instrument is used to focus sound waves on a blood vessel, blood flow is measured as echoes bounce of red blood cells.

• Echocardiography: pulses of high frequency sound waves are transmitted into the chest, and echoes returning from the walls, chambers and surface of the heart are electronically plotted and recorded.

• Radioactive cardiac scan(Thallium scan): A radioactive substance is injected intravenously and its accumulation in heart muscle is measured with a scanner.

• MRI angiogram: magnetic waves are beamed at the heart and an image is produced to see for any CHD, cardaic mass

• Cardiac mapping for micro arrythmias• Implantable cardioverter defibrillator (ICD)

• Cardioversion: a very brief discharge of electricity are applied across the chest to stop a cardiac arrhythmia and to allow a normal rhythm to begin.

• CABG: vessel grafts consisting of veins taken from other parts of the body are anastomosed to existing coronary arteries to detour around blockages in the coronary arteries and to keep the myocardium supplied with oxygenated blood.

• ECG: process of recording the electricity flowing through the heart. • Endartectomy:This procedure involves surgical removal of innermost lining

of an artery when it is thickened by fatty deposits and thrombosis.• Extra corporeal circulation: Heart lung machine is used as a bypass to divert

blood from the heart and lungs while the heart is being repaired. • Heart Transplantation: a donor heart is transferred to a recipient. • Holter monitoring: A compact version of an electrocardiogram is worn during

a 24 hour period to detect cardiac arrhythmias.• PTCA(percutaneous transluminal coronary angioplasty): A catheter

equipped with a small balloon on the end is inserted via the femoral artery and threaded up to the aorta and into the coronary artery. The balloon is then inflated compressing the fatty deposits or plaques against the side of the artery and opening the artery to allow the passage of blood.

• Ballon Valvuloplasty: opening the mitral stenosis• Stress Test: Also known as exercise tolerance test, this procedure

determines the heart’s response to physical exertion and an ECG and blood pressure are measured to determine the heart’s response to stress.

• Anticoagulation therapy: drugs such as tissue type plasminogen activator and streptokinase that dissolve clots are injected into the blood stream in patients diagnosed as having a coronary thrombosis.

• Antiarrhythmic Drugs • ADENOSINE • AMIODARONE • Atropine• β-ADRENOCEPTOR ANTAGONISTS (e.g. METOPROLOL, SOTALOL) • Bretylium • CALCIUM CHANNEL BLOCKERS (e.g. DILTIAZEM, VERAPAMIL) • digitoxin • digoxin • disopyramide • disopyramide • dofetilide • flecainide • ibutilide • LIDOCAINE • mexiletine • PROCAINAMIDE • propafenone

• Management of Acute and Chronic Heart Failure

• ANGIOTENSIN CONVERTING ENZYME INHIBITORS (e.g. ENALAPRIL) • ANGIOTENSIN RECEPTOR ANTAGONISTS (e.g. LOSARTAN) • ADRENOCEPTOR ANTAGONISTS (e.g. CARVEDILOL;

METOPROLOL) • ADRENOCEPTOR AGONISTS (e.g. DOBUTAMINE; DOPAMINE) • DIGOXIN• DIURETICS (e.g. Furosemide; SPIRONOLACTONE) • Inamrinone • PHOSPHODIESTERASE INHIBITORS (e.g. INAMRINONE; MILRINONE) • NESIRITIDE • VASODILATORS (e.g. HYDRALAZINE, NITROPRUSSIDE)

Antihypertensives and Related Drugs

• ANGIOTENSIN (I & 11)

• atenolol • CAPTOPRIL • CLONIDINE • diazoxide • DILTIAZEM • ENALAPRIL • esmolol • FUROSEMIDE • guanabenz • HYDRALAZINE •HYDROCHLOROTHIAZIDE • indapamide

• labetalol • losartan • metazolone • methyldopa • METOPROLOL • minoxidil• NIFEDIPINE • NITROGLYCERIN (i.v.) • nitroprusside • pindolol • PRAZOSIN • PROPRANOLOL • quinapril • reserpine • spironolactone • triamterene • VERAPAMIL

Antianginal Drugs • ANTIPLATELET AGENTS

(e.g. Clopidogrel) • ADRENOCEPTOR ANTAGONISTS (e.g.

PROPRANOLOL) • CALCIUM CHANNEL

BLOCKERS (e.g. NIFEDIPINE) • VASODILATORS

• Antihyperlipidemic Drugs – • CHOLESTYRAMINE – • colestipol – • ezetimibe – • FIBRIC ACID DERIVATIVES

(e.g. GEMFIBROZIL, FENOFIBRATE)

– • HMG CoA REDUCTASE INHIBITORS (e.g. ATORVASTATIN, LOVASTATIN, PRAVASTATIN)

– • nicotinic acid