Heart

 

The heart is an important organ in the function of circulating blood throughout the body. It is critical to keeping the body alive and healthy.

The lungs and the heart have a very important relationship. It is here that the exchange of deoxygenated and oxygenated blood occurs. The deoxygenated blood is pumped into the lungs via the pulmonary artery. The oxygen exchange takes place and the blood returns to the heart via the pulmonary vein.

The heart itself is a fist-sized organ which is located a little to the left of the centre of the body. The heart is divided into two halves and four chambers. Each part of the heart plays a role in pumping blood whether in or out of the heart and lungs.

As blood leaves the heart and circulates the body it is full of oxygen. Other organs and parts of the body make use of this oxygenated blood to keep the body functioning and in a state of balance. Upon return to the heart, the blood is empty of oxygen and requires nourishment.

Blood returns to the heart via the right heart and vena cava. It enters the right atrium, passes through the tricuspid valve to enter the right ventricle. From here it passes through the pulmonary valve into the pulmonary artery. Here the blood leaves the heart and makes its way to the lungs. It returns back to the heart via the pulmonary vein, and enters the left heart or left atrium. Here the blood passes through the mitral valve into the left ventricle. The left ventricle is separated from the aorta by the aortic valve. The aorta pumps blood back into the body to complete another cycle of circulation. All of these valves prevent the backflow of blood.

If any of these heart halves or valves have a weakness or are damaged, heart problems can occur. Some problems are high blood pressure or the hardening of arteries. Poor circulation can manifest in the body as puffiness, tiredness and edema. The heart requires activity to keep it healthy, as well as the right minerals, vitamins and nutrients. Exercise and diet play an important role in heart health. This also includes emotional health.

The heart is a hollow muscle. It sits in the mediastinum (middle thoracic cavity) between the two lungs. The blood leaves the heart and enters the aorta, then arteries, arterioles and capillaries, where the exchange of oxygen and nutrients for waste takes place. It then makes its way back to the heart via the venules, veins and reenters the heart via the superior and inferior vena cava.

The neighbouring organs of the heart are the lungs, thymus, sternum, esophagus, descending aorta, superior and inferior vena cava and diaphragm.

Position is two thirds to the left and one third to the right in the middle thoracic cavity. The size is approximately the size of the fist and is formed like a ball. The cardiac apex lies on top of the diaphragm, and the heart has a right to left and back to front tilt.

The heart has three different layers: endocardium, myocardium and pericardium.

The endocardium is the inner heart membrane and gives the heart cavity its smooth inner lining. It is made of squamous epithelium. Nourished by underlying connective tissue. The heart valves are made of endothelium too and so if the endocardium is infected, so are the valves. The myocardium is the heart muscle. It is made of a mix of smooth and striated muscle. The left heart muscle is thicker than the right heart muscle tissue. Normal heart weight of an adult is 300 grams. The heart is able to change depending on its health, activity and so on. The largest size is 500 grams (critical heart weight) for an athlete and smallest size is 150 grams of an elderly person. Critical heart weight ensures the heart cannot get bigger, because it would require too much effort from supporting tissue and organs. Pericardium is the heart sac, which surrounds the heart muscle. It is a double sac. It has a visceral lobe, which grows together with the heart. Parietal sac is the outer sheath of the sac. Potential space is filled with fluid and lies between the visceral and parietal lobes. The pericardium enables heart movement and prevents friction with surrounding organs, protects it from infection, overstretching and stabilises its position. Partly attached to the pleura and diaphragm. The pericardium comprises epithelium and connective tissue. Heart hypertrophy: increased heart size without an increase in cell numbers. Cell size expands. Heart hyperplasia: cell expansion can no longer be sustained. Cells reduce in size, and cell numbers increase instead. Heart dilatation: expansion of heart cavity, which leads to heart insufficiency.

The heart is divided into four compartments: firstly, the left and right halves, which are separated by a septum. Then each heart half is divided into atria and ventricles. These are known as chambers. These are separated by septum. The right atria receives blood returning to the heart. The right ventricle sends oxygen poor blood to the lungs. Oxygen rich blood returns to the heart via the left atrium and leaves the heart via the left ventricle.

The heart has two types of valves which control the backflow of blood. The two valve types are: atrioventricular valve and semilunar valve. The atrioventricular valve exists between the atria and ventricles. The semilunar valve exists between the ventricles and the descending aorta.

Atrioventricular valve: one valve contains two flaps (bicuspid valve) and the other three flaps (tricuspid valve). The flaps are attached to papillary muscle. Tricuspid valve: receives blood into the right atria and funnels it into the right ventricle. Bicuspid valve: blood moves from the left atria into the left ventricle. Semilunar valve: connected to vessel walls and contains three cusps. Does not have any papillary muscle. Aortic heart valve: between the left ventricle and the aorta Pulmonary valve: is a tricuspid valve between the right ventricle and pulmonary artery.

The valves are connected to a ring made of connective tissue. The valves open and close when the heart contracts. Blood flow is always one way.

The myocardium and pericardium are nourished by the coronary vessels. These vessels stem from the aortic heart valve. The left and right coronary arteries feed and nourish the left and right heart halves. Blood flows through the coronary arteries into arterioles and then to the capillaries. The return of the deoxygenated blood goes from the venules to the coronary sinus where it leaves the heart muscle and enters the right atrium.

The right heart half pumps blood into the small pulmonary circulation, whereas the left heart half pumps blood into the large pulmonary circulation.

Pulmonary circulatory system begins at the right ventricle, where blood enters pulmonary arteries and capillaries, where the gas exchange takes place in the lungs. Blood flows back via the four (left and right lungs) pulmonary veins to the left atrium.

Systemic circulatory system begins at the left ventricle, where the blood enters the arteries, flows into the arterioles and capillaries, reaches every cell int he body, exchanges supplies for waste, then returns to the heart collecting in the venules, back into the veins (superior (upper body) and inferior (lower body) vena cava) and into the right atrium.

Oxygen rich blood enters the left atrium from the lungs and exits the heart from the left ventricle Oxygen poor blood enters the right atrium from the body and exits the right ventricle into the lungs

Heart beat consists of systole and diastole beats. Systole represents the contraction of the heart muscle. Diastole represents the relaxation of the heart muscle. Systole is responsible for pumping blood out of the heart. Diastole is responsible for pumping blood into the heart. This contraction and relaxation interplay is mimicked in the atria and ventricles. When the atria are in systole, the ventricles are in diastole. So the atria and ventricles work in opposition.

Stroke volume is the amount of blood pumped out of the ventricle into the aorta during systole. Norm is 70-100 ml.

Cardiac output refers to the amount of pumped pumped out of the ventricle into the aorta during systole in one minute. Norm is 5-7 litres. Multiply stroke volume by beats per minute (pulse rate).

Blood flow diagram

Oxygen-depleted blood flows into the superior and inferior vena cava | into the right atria (end of the systemic circulatory system) | through the tricuspid valve into the right ventricle | through the pulmonary valve into the pulmonary artery (start of the pulmonary circulatory system) | into pulmonary arterioles, capillaries and into the alveoli. Gas is exchanged | back into pulmonary venules into pulmonary veins | into the left atrium (end of the pulmonary circulatory system) | through the mitral valve into the left ventricle | through the aortic valve into the aorta (start of the body circulatory system) | into smaller arteries and arterioles | finally into capillaries where cells are nourished | into small venules and larger veins | back into the superior and inferior vena cava

Heart sounds: the heart has two sounds. The first sound is the tension of the ventricular musculature. The sound is caused by the closing of the atrioventricular valve. The second sound is the closing of the semilunar valve. It is not as loud as the first sound.

Heart cycle: 3 things are important - intrinsic, neural and hormonal control. The intrinsic control involves in the sinus nodes. The neural control involves the sympathetic and parasympathetic nervous systems. The hormonal control involves adrenaline.

Intrinsic: the heart needs its own electricity in order to work. Special heart muscles called pacemakers are located in the sinus nodes. They are responsible for excito-conduction. Located at the right atrium where the superior vena cava is. Heart muscle cells are always primed, and the pacemakers are the highest primed. If this sinus node electrical system is defective, then the AV nodes will take over. The heart will beat slower now. If the AV system is also defective, then the heart muscle cells will start to give their own orders. This will lead to ventricular fibrillation. The heart will no longer be coordinated. Ventricular ejection will be zero. Cardiac arrest will follow. Sinus nodes = 60-80 bpm. AV nodes = 40-60 bpm. Action potential starts in the sinus nodes, moves to the atria, and collect in the atrioventricular nodes. Moves to the Bundle of His, to the Purkinje fibres, which deliver the action potential to the individual heart muscle fibres. Refractory period and all and nothing principle also apply here. Mass contraction means there will be a window of nothing for 0.4 seconds. Neural: the heart is adapted to specific needs using neural control. Think of the two systems - fight or relax. Accelerate or slow down. Hormonal: adrenaline is produced by the adrenal medulla and helps to accelerate the heart (sympathetic system).

Examination

Inspection: sometimes this is enough to see if the patient has a heart problem. Check for cyanotic discolouration. This indicates lack of oxygen. Shortness of breath, edema and bulging veins also indicate right heart insufficiency.

Palpation: cardiac apex apical pulse can be felt during systole. Found at the fifth intercostal space, a little to the left of the mid clavicular line. If it is displaced, depending if to the right or left, this will indicate the opposite side of the heart is enlarged.

Percussion: use this to determine the heart’s dimensions and form. There are two sounds: absolute heart dullness and relative heart dullness. The first is lighter and softer, and indicates the heart form. The second is stronger and louder and covered by pulmonary tissue.

Auscultation: use a stethoscope. It will help you determine between heart sounds and murmurs. You’ll also be able to hear septum and valve defects. The appropriate auscultation points are as follows: aortic valve 2nd - ICS right parasternal, pulmonary valve - 2nd ICS left parasternal, tricuspid valve - 4th ICS right parasternal, mitral valve - 5th ICS left of the MCL. Main goal is to see if there is a defect or problem. If there is a problem, send your patient to a cardiologist.

Heart sounds: important to know the different heart sounds.

1st heart sound is duller than the other. This involves the tensioning of the ventricular musculature. You can hear the beating of the AV valves. Listen near the 4th and 5th ICS above the cardiac apex. 2nd heart sound is lighter than the other. This involves the beating of the semilunar valves. Listen at the heart base around the 2nd ICS.

Best if you practice on friends and family to get used to the sounds. Patient should sit or lie down.

Split heart sounds: There may be a splitting of sounds, which is when the AV and semilunar valves don’t close at the same time. If there is a split of the 1st heart sound, then send your patient to a cardiologist. There is an underlying pathological reason. If there is a split of the 2nd heart sound, then it may be a physiological or pathological reason. When breathing in, there is a venous backflow, which may be heard. The left heart has more pressure than the right heart. A split of the 2nd heart sound has a smaller pause between the sounds than in the case of a 3rd heart sound.

Important pathological heart sounds: hypertonia - 2nd heart sound loud; mitral valve stenosis - 1st heart sound loud; mitral valve insufficiency - 1st heart sound soft.

There are also 3rd and 4th heart sounds: the 3rd means there are 3 sounds, 1 extra one after the 2nd heart sound. The 4th means there are also 3 sounds, one extra one before the 1st heart sound. Both of these have pathological and physiological reasons. The symptoms will help you determine which it is. If you see any suspect symptoms, send your patient to a cardiologist.

Causes: physiological is common in youths, kids and last trimester of pregnancy; pathological is common in heart insufficiency.

Heart murmurs: caused by turbulence in the blood stream, as well as valve and septum defects. There are pathological, functional and accidental heart murmurs.

Pathological: caused by organic changes to the heart and vessels near the heart. Common is heart valve defect, heart sac inflammation. Functional: caused by increased blood flow speed courtesy of fever, anemia or hyperthyroid-induced tachycardia. These noises don’t change the heart. Best heard through 2nd and 3rd ICS, before the 2nd heart sound. Accidental: no change to heart or blood flow, normal in a healthy person. Found in kids and slim people.

Blood pressure: arterial pressure of the peripheral artery is usually measured during blood pressure. Usually the upper arm. What is measured is the pressure pattern of the artery, and not the heart. It is influenced by vessel elasticity, resistance and heart performance (how much blood is pumped out of the left ventricle). The method is based on Italian Riva-Rocci method.

Place the cuff around the arm at the same level as the heart. Remove any clothing out of the way. Lie the arm on a table, keep it bent at the elbow. You should be able to slide your index and middle finger between the cuff and the arm. This is tight enough. The cuff should cover 2/3 of the upper arm. So the cuff width should be around 14 cm.

Close the air valve and pump the cuff with air. The upper arm artery should be pinched. Then add an extra 30 mm Hg. You should not feel a pulse anymore.

Use the stethoscope and place it at the elbow. As you release the pressure, do so at a rate of 2-3 mm Hg per second. Do it until you hear the arterial pulse again. As soon as you hear the normal pulsation sounds, called Korotchow, look at the gauge and determine the systole blood pressure. Release more air until no pulsations are heard anymore. Measure the diastole blood pressure.

If you make a mistake, take the cuff off and leave the arm to rest for 1 minute. Then try again. Do even both arms. There may be a difference of 15-20 mm Hg between both arms. This is normal.

You can even measure the blood pressure in the leg. Use a special cuff, and place it around the upper leg. Use a stethoscope at the back of the knee and listen to the popliteal artery. Leg can be 20 mm Hg higher than the arm.

If you get an error, there are several reasons why:

High blood pressure error: Cuff too tight or too loose, blood congestion, air released too slowly, cuff below heart line Low blood pressure error: Clothing covering arm, cuff too wide, arm too thin, cuff above heart line Irregularities: Air not released, stethoscope not used properly, not enough air pumped into cuff, air released too quickly Contraindications: Lymphodema and paralysis in arm, hypertension crisis, pulse felt above 230 mm Hg

Electronic Devices

ECG: Measures electrical current in heart. Sinus nodes are responsible for electrical arousal. Tells us about heart rhythm, frequency and disturbances to electrical current. Heart attack can be determined due to dead tissue where no current can flow. Different ECGs:

Rest - lying down Stress - helps to test for any coronary heart disease, bicycle ergometer used Long term - measures over a 24 hour period (min)

Each line represents a single phase of heart cycle. Types of lines have different meanings:

P waves - start of the heart cycle, atria excitation PQ lines - begins with p wave, ends with q spike. Interval between atria and ventricle excitation Q spike - ventricle septum excitation QRS complex - spreading of ventricle excitation ST line - complete ventricle excitation T wave - minimised ventricle excitation QT period - time from start of excitation to plateau U wave - not known what this means

X Ray: Tells us of position, size and form of heart.

Ultrasound: Measures thickness and function of heart valves, as well as pericardial effusion.

Phonocardiogram: Records heart sounds and murmurs.

Heart Catheter: Saturation of oxygen in blood and pressure measured in heart.

Coronary Angiogram: X ray contrast fluid given and x ray can be taken. Good for heart attack patients, to determine if operation is needed.

Heart Insufficiency: If the heart is defect it cannot pump blood to and from the heart. Both sides of the heart can be affected separately or at the same time.

Forwards failure: Pumping ability is poor. Left ventricle cannot pump out, and right ventricle cannot pump blood to lungs. Backwards failure: Blood returning to heart is affected. If left heart affected, blood stuck in lungs. If right heart affected, blood stuck in veins.

Different grades of this disease. Stress can affect volume and blood pressure. Even when relaxing, symptoms can be seen. There can be acute or chronic development.

Causes: valve defect, myocarditis, cardiomyopathy, pericarditis, coronary disease, heart rhythm disorder, high blood pressure Heart Hypertrophy: occurs when the heart valve is narrow and the heart compensates with using more power to pump. The heart grows in heart muscle mass. Cell count increases. Limit is 500 grams. Over this limit, heart muscle cells degenerate. Heart Hyperplasia: this is the next stage, when the heart muscle cells decrease in size. They are too small for the workload. Heart Dilatation: this is the final stage, when the heart cavity expands. In an athlete the expansion is harmonious. In a diseased heart, the heart does not pump properly.

Left Heart Failure: either a forwards or backwards dysfunction.

Forwards dysfunction: consequences are peripheral cyanosis, circulation is slow, oxygen deprivation, discolouration. Backwards dysfunction: blood in lungs is stuck in left atrium and lung. This causes pulmonary hypertension. Symptoms: loss of breath while resting, cyanosis caused by lack of gas exchange, congestive bronchitis when the lungs are overfilled with blood, orthnopea which is shortness of breath while lying down (can also be caused by liver and neuromuscular disease, asthma and chronic bronchitis), cardiac asthma where the blood level in pulmonary circulation increases and causes hypertension, pulmonary edema as a consequence of the previous, too much fluid sits in the alveoli, bronchia and lungs. Diagnosis: cyanosis, tachypnea and difficulty breathing, background noises (wet rattling) Therapy: same as right heart failure

Right Heart Failure: result of left heart failure, and pulmonary hypertension. Heart has to work very hard.

Causes: left heart failure, cor pulmonale where the pressure increases between lung and right heart, and valve defect. Symptoms: blocked veins in neck, hands, sublingual, congested liver where a backlog of blood is and blood pressure is increased, gastrointestinal complaints where the portal vein is affected and blocks the spleen, intestines and stomach, congested kidneys where pressure on the inferior vena cava affects the kidneys, nightly ankle swelling because fluid cannot be transported away, nocturia which is the release of this excess fluid, and weight increase by 5 kilos. Diagnosis: raised veins, swollen ankles, cyanosis, tachynopea, difficulty breathing, enlarged liver, pulmonary hypertension. Therapy: treat with Hawthorn, squill, lily of the valley, adonis vernalis. Breathing therapy and Kneipp baths.

Inflammation of the Heart

Divided into: endocarditis, myocarditis and pericarditis.

Endocarditis: risk is that the other layers and valves will be affected too. Healing can cause scarring and distortion, and valve stenosis and insufficiency. Causes: autoimmune and bacterial infection Rheumatic Endocarditis: no obvious pathogen. Immune system attack. Antibodies fight own tissue. Causes: rheumatic fever and Morbus Bechterew, PCP and LE. This is quite rare though. Acute Bacterial Endocarditis: rare, caused by streptococca, strong immune weakness or after effects of heart surgery. Symptoms: shivering, high fever, heart failure, anemia. Weight loss, weakness, high embolism danger. Clots of the heart valves can dislodge easily. If this happens in the right heart then it can lead to pulmonary embolism. If it happens in the left heart it can cause a stroke, because it will swim through the aorta and up to a cerebral artery. Or even to the legs. Therapy: send the patient to a clinic for antibiotics. Subacute Endocarditis: Appears in prestage of heart damage after rheumatic fever. Less dramatic as the acute version. Cause is streptococca in the inner membrane, which develops out of pus or chronic sinusitis. Symptoms: 38 degree fever, night sweats, heart and joint complaints, loss of appetite and weight, petechiae on the butt, extremities and ocular fundus, arterial embolism, heart failure with ikterus, spleen swelling and cyanosis. Therapy: send to a doctor for antibiotics. Myocarditis: Can be acute or chronic, or progression. Can spread or stay within limits. Causes: rheumatic fever, rheumatism, infections from virus, fungus, bacteria, protozea, toxins from penecillin, cytostatics Symptoms: underlying disease causes this, relative tachycardia expect up to 100, extrasystole, retrosternal chest pain, cyanosis, bradycardia, heart failure, difficulty breathing, cardiogenic shock Diagnosis: heart sounds are very soft Therapy: send to a doctor for medicine Pericarditis: Infection and inflammation of the cardiac sac, visceral and parietal lobes affected. Cause: can be primary or secondary illness, after pathogens such as bacteria, rheumatic related illnesses Progression: acute, chronic, chronic constrictive, pericarditis exsudativa, pericarditis sicca Acute Pericarditis: Comes with pericardial effusion, caused by infected exudation of protein rich fluid released by expanded capillaries Symptoms: pain behind chest bone, fever, sweating, accelerated breathing Chronic pericarditis: Develops out of an acute stage. Symptoms: small effusion with no paid behind chest wall, breathing problems, heart failure, hypotonia Chronic constrictive pericarditis: Special form, scarred shrinkage of cardiac sac, or attached growth of inner and outer lobes during healing of pericardium. Performance is hindered. Symptoms: breathing difficulties, hypotonia, tachycardia, heart failure, calcium deposits in cardiac sac and armoured heart. If there is an effusion, then it is a wet infection. Otherwise with it, it is dry. Pericarditis exsudativa: Pericardial cavity filled with infected fluid. If at first it was dry and with a lot of pain, then when it becomes wet, the pain will go. No friction sounds. But with increased fluid, the heart and lungs will constrict. Symptoms: breathing difficulty, soft heart sounds, right heart failure, fluid backlog, tachycardia, hypotonia, cyanosis, shock, cardiac sac tamponade (bleeding), cardiac arrest

Heart valve defects

Can be congenital or develop over time. If acquired then most likely cause is rheumatic endocarditis. During healing, scar tissue develops, which distorts the valve. Stenosis or insufficiency can develop.

Valve failure means valve can no longer close properly, so blood can leak out. Valve stenosis means valve does not open properly, opening is narrow, creates backlog of blood.

These two mostly occur together. Combined vitium.

Symptoms: strength of symptoms depend on opening size. If narrow but heart muscle compensates, then no symptoms. But if narrowing is severe and heart muscle compensates (by growing) then blood still cannot pass. If blood cannot be pumped at all, there is death. Valve failure is the same thing. Symptoms depend on amount of blood that moves back and forth.

Mitral valve stenosis: Rheumatic fever since childhood. 20-30 years later complaints start.

Pathogenesis: if valve cannot open, then blood backflow in left atrium. Atria muscles hypertrophise, and work harder. Left ventricle atrophises due to lack of blood flow. Severity depends on if atrium muscle can balance the situation or if there will be too much blood backflow. If the latter, then blood will flood the lungs. Gas exchange won’t take place. Left heart failure. If lungs cannot handle increased blood, then blood pressure will rise and right heart will be affected too. This could cause failure, and symptoms like nightly ankle swelling, nocturia, raised veins, weight increase. Left sided failure: dyspnoe, cardiac asthma, congestive bronchitis, coughing, pulmonary edema with blood Right sided failure: nightly ankle swelling, nocturia, edema, venous congestion, congestive liver, spleen and kidneys Diagnosis: cyanosis, mitral face, 1st heart sound very loud Complications: blood clots in left atrium, which can cause embolism, then stroke. Therapy: valve could be replaced, with antibiotics, digitalis, beta blocker, diuretics and anticoagulants. Avoid physical exertion and streptococcal infection. Light form of illness shows in facial discolouration, with light red, butterfly shaped and more pronounced around the nasal bridge and chin. Cor pulmonale caused by lung infection. Blood pressure increases and right heart failure comes. Blood no longer filled with oxygen. Organs are undernourished, so too is skin. Skin looks cyanotic. Red blood cells increase to compensate and the eyes can look red and inflamed.

Mitral valve failure

Causes: rheumatic related fever, as well as congenital division of valve leaflets or bacterial endocarditis. Pathogenesis: blood flows back to the atrium from the left ventricle. Left ventricle hypertrophises as a result of pumping blood into peripheral system. Atrium is increased and can cause dilatation.