Anatomy and Physiology of the Heart PDF

 Anatomy and Physiology The heart comprises two muscular pumps working in a series, covered by(pericardium) Atrioventricular valves (tricuspid on the right side, mitral on the left) separate the atria from the ventricles...

 Anatomy and Physiology The heart comprises two muscular pumps working in a series, covered by(pericardium) Atrioventricular valves (tricuspid on the right side, mitral on the left) separate the atria from the ventricles. The pulmonary valve on the right side → separate the ventricles from the pulmonary system Aortic valve on the left side → separate ventricles and systemic arterial circulation Cardiac contraction is coordinated by specialised groups of cells. The cells in the sinoatrial node (SA node) normally act as the cardiac pacemaker. Subsequent spread of impulses through the heart ensures that atrial contraction is complete before ventricular contraction (systole) begins. At the end of systole the ventricles relax and the atrioventricular valves open, allowing them to refill with blood from the atria (diastole). Right heart → pumps deoxygenated blood returning from the systemic veins into the pulmonary circulation at relatively low pressures. Left heart → receives blood from the lungs and pumps it round the body to the tissues at higher pressures Chest pain Intermittent chest pain due to intermittent myocardial ischaemia (angina pectoris) is typically a dull discomfort, often described as a tight or pressing ‘band-like’ sensation akin to a heavy weight. stable angina (caused by chronic narrowing in one or more coronary arteries), precipitated by exertion and walking in cold or windy weather, after a large meal or while carrying a heavy load the pain is relieved by rest and/or sublingual glyceryl nitrate (GTN) spray, and typically lasts for less than 10 minutes.  unstable angina (caused by a sudden severe narrowing in a coronary artery), there is usually an abrupt onset or a worsening of chest pain episode that may occur on minimal exertion or at rest. Don’t forget SOCRATES Acute chest pain Myocardial infarction causes symptoms that are similar but severe and prolonged than, those of angina pectoris. Associated features include restlessness, breathlessness and a feeling of impending death (angor animi). Radiation to one or both arms/shoulders, an association with exertion, sweating, nausea or vomiting. Pericardial pain is typically a constant anterior central chest pain that may radiate to the shoulders. It tends to be sharp or stabbing in character, exacerbated by inspiration or lying down, and relieved by sitting forwards. It is caused by inflammation of the pericardium secondary to viral infection, connective tissue disease or myocardial infarction, or after surgery, catheter abla- tion or radiotherapy. Aortic dissection (a tear in the intima of the thoracic aorta) is a life- threatening condition which is often missed. It is associated with abrupt onset of very severe, tearing chest pain that can radiate to the back (typically the interscapular region) and may be associated with profound autonomic stimulation. Over 90% of patients report the pain as severe or their ‘worst ever’, and the onset is sudden in 85% of cases; the absence of abrupt onset makes the diagnosis less likely. If the tear involves the cranial arteries → syncope, stroke upper limb arteries → upper limb pulse asymmetry. Predisposing factors include: connective tissue disorders, such as Marfan’s syndrome family history of aortic disease, known aortic valve disease, previous aortic manipulation and known thoracic aortic aneurysm. > 38 min  Dyspnoea (breathlessness) Heart failure is the most common cardiovascular cause of both acute and chronic dyspnoea Other cardiovascular causes include valvular heart disease, pulmonary embolism and arrhythmia. non cardiac dyspnoea may be due to pulmonary disease, obesity, anaemia, neuromuscular disease, chest wall disorders, pregnancy, hyperventilation syndrome and anxiety disorders. Patients with acute heart failure and pulmonary oedema >> prefer to be upright, patients with massive pulmonary embolism are often more comfortable lying flat and may faint (syncope) if made to sit upright SOB caused by myocardial ischaemia is known as ‘angina equivalent’. It may occur + - chest discomfort, especially in patients who are elderly or who have diabetes. Heart Failure Exertional dyspnoea is the symptomatic hallmark Orthopnoea, dyspnoea on lying flat, may occur in patients with heart failure >> signifies advanced disease or incipient decompensation Lying flat increases venous return -> pulmonary oedema. The severity can be graded by the number of pillows used at night: ex‘three-pillow orthopnoea’ Paroxysmal nocturnal dyspnoea ( same mechanism ) >> sudden SOB wakes the patient from sleep Patients may choke or gasp for air, sit on the edge of the bed and open windows in an attempt to relieve their distress. asthma causes night time dyspnoea they have >> cough and wheeze, while heart failure may also produce frothy white or blood-stained sputum. Bendopnoea is a symptom of dyspnoea when bending forward at the waist and is associated with increased cardiac filling pressures , (18–49%) in patients with heart failure , it is not diagnostic and may occur in other conditions. In acute dyspnoea, ask about: duration of onset background symptoms of exertional dyspnoea and usual exercise tolerance associated symptoms: chest pain, syncope, palpitation or respiratory symptoms (cough, Supraordinary sputum, wheeze or hemoptysis) In patients with chronic symptoms, ask about: Ordinary relationship between symptoms and exertion degree of limitation caused by symptoms and their impact on everyday activities subording effect of posture on symptoms and/or episodes of nocturnal breathlessness associated symptoms: ankle swelling, cough, wheeze or sputum. ↑ Palpitations Unpleasant awareness of the heart beating Healthy people are occasionally aware of their heart beating with normal (sinus) rhythm, especially after exercise or in stressful situations The sensation is often more common in bed at night and slim people may notice it when lying on their left side. HR > 100 Tachy arrhythmia Abnormal rhythm HR < 60 Brady arrhythmia Delays impulse Ask about: nature of the palpitation: rapid, forceful or irregular ( ex, atrial fibrillation) or regular (ex , sinus tachycardia) ? Can you tap it out ? timing of symptoms: speed of onset & offset frequency and duration of episodes Triggers ? relieving factors ? · associated symptoms: presyncope, syncope or chest pain D history of underlying cardiac disease. ·  ✔ " " ✔ Arrhythmias Supraventricular tachycardia Ventricular tachycardia Origin of impulse above AV node Origin of impulse below AV node Sinus tachycardia Atrial fibrillation Ventricular tachycardia PSVT ( paroxysmal supra ventricular ventricular fibrillation tachycardia) rapid, regular palpitation more likely to cause presyncope decrease by vagal stimulation>> or syncope Valsalva breathing manoeuvres or affect old patients with history of carotid sinus pressure. cardiac disease Affect young & healthy people Life threatening risk increases with : From the Atria >> maybe associated previous MI or cardiac surgery with high Atrial natriuretic peptide >> associated syncope or severe chest polyuria pain family history of sudden death Wolff–Parkinson–White syndrome significant structural heart disease like hypertrophic cardiomyopathy , AS. impulse impulse from From sAnode Atrium ↑ Hyperthyroidism elderly , HTN  ✔ ✔✔ # ! ! Ectopic beats (extrasystoles) : Benign cause of palpitation happens at rest and are abolished by exercise. The premature ectopic beat → small stroke volume & impalpable impulse → due to incomplete left ventricular filling. ‫ﻣﺎ ﻟﺣق ﯾﻌﺑﻲ دم‬ The subsequent compensatory pause ‫ اﻟﻧﺑﺿﺔ اﻟﻠﻲ ﺑﻌدھﺎ‬leads to → ventricular overfilling & forceful contraction with the next beat. ‫ﻋﺑﻰ دم ﺑﺷﻛل ﻣﻧﯾﺢ‬ Patients often describe missed beats sometimes followed by strong heart beat jolt Syncope and presyncope Syncope : Transient loss of consciousness due to transient cerebral hypoperfusion and episodes are typically characterised by rapid onset, short duration, and spontaneous complete recovery. presyncope : sensation of lightheadedness and impending loss of consciousness without progressing to actual LOC Arrhythmia postural hypotension Mechanical obstruction Vasovagal attack Bradyarrhythmia : fall of more Aortic stenosis Reflex or SA disease than 20 mmHg Hypertrophic neurocardiogenic in systolic blood obstructive excessive autonomic AV block: Stokes pressure on cardiomyopathy reflexes → sudden Adams attacks. standing (HOCM) bradycardia) and/or Rate-limiting drugs Elderly Massive vasodilatation. SVT rarely cause Hypovolemia pulmonary syncope Autonomic embolism triggered in healthy V tach neuropathy people following a period of prolonged standing or a painful or emotional stimulus (sight of blood) lightheadedness, tinnitus, nausea, sweating and facial pallor, and a darkening of vision before loss of consciousness. When laid flat to aid cerebral circulation the individual wakes up, often flushing from vasodilatation and nauseated or even vomiting due to vagal overactivity. If the person is held upright → continued cerebral hypoperfusion delays recovery and may lead to a seizure and a mistaken diagnosis of epilepsy  In patients who present with syncope, ask about: circumstances and preceding symptoms: palpitation, chest pain, lightheadedness, nausea, tinnitus, sweating or visual disturbance duration of LOC , appearance of the patient while unconscious and any injuries sustained (detailed witness history) time to recovery of full consciousness In patients with presyncopal symptoms, ask about: exact nature of symptoms and associated features such as palpitation precipitants for symptoms, such as postural change, prolonged standing, intense emotion or exertion frequency of episodes and impact on lifestyle possible contributing medications, such as antihypertensive agents The main differential diagnosis of syncope is seizure lightheadedness and presyncope must be distinguished from dizziness or vertigo due to non- cardiovascular causes. predictors of vasovagal syncope include a history of syncope or presyncope with pain or medical procedures, an age less than 35 at first syncopal episode, prodrome of sweating, warmth or abdominal discomfort or a postdrome of nausea. In patients with hypersensitive carotid sinus syndrome, pressure over the carotid sinus may lead to reflex bradycardia and syncope. Cardiac tumours, such as atrial myxoma, and thrombosis, or failure of prosthetic heart valves are rare causes of syncope Oedema Excess fluid in the interstitial space (tissue swelling) Unilateral Bilateral Heart Failure DVT Renal Failure Lymphedema cirrhosis Hypoalbuminemia Baker’s cyst rupture Nephrotic syndrome Loss of protein in urine It is usually gravity dependent and so is seen especially around the ankles, or over the sacrum in patients lying in bed. other causes include chronic venous disease, vasodilating calcium channel antagonists (such as amlodipine) and hypoalbuminaemia.  Other symptoms of cardiac disease Infective endocarditis ( infection of a heart valve ) → presents with non-specific symptoms, including weight loss, tiredness, fever and night sweats. Embolisation of intracardiac thrombus, tumour (such as atrial myxoma) or infective ‘vegetations’ may produce symptoms of stroke , acute limb ischaemia , or acute mesenteric ischaemia. Advanced heart failure may result in either abdominal distension due to ascites, or weight loss and muscle wasting (‘cardiac cachexia’) due to a prolonged catabolic state. Past Medical History previous cardiac disease, investigations and interventions Also ask about: hypertension, diabetes mellitus and hyperlipidaemia rheumatic fever or heart murmurs during childhood potential causes of bacteraemia in patients with suspected infective endocarditis, such as skin infection, recent dental work, intravenous drug use or penetrating trauma connective tissue diseases (pericarditis and Raynaud’s phenomenon), Marfan’s syndrome (aortic dissection) and myotonic dystrophy (atrioventricular block). As Drug history Dexamethasone =>ibuprofen , naproxen Family history Ask about premature coronary artery disease in first-degree relatives (