Cardiovascular System

What is haemotology?

Haematology is the science of  blood, blood forming tissues and  disorders of the blood

What is the average volume of blood?

• Male = 5-6 litres

• Female = 4-5 litres

• (Plasma volume increases during pregnancy)

What is the temperature of blood?

37 degrees Celsius

How is blood transported

Connective tissue

What is the pH of blood?

• pH - slightly alkaline

• 7.35-7.45

How is blood made to be protective?

• Clotting protects against excessive blood loss

• Phagocytic white blood cells and antibodies protect against infection and disease

What are the constituents of blood?

1. Plasma

2. White blood cells (leucocytes)

3. Platelets (thrombocytes)

4. Red blood cells (erythrocytes)

Describe RBC?

• Small

• Biconcave

• No nucleus (mature RBCs)

• Flexible

• Life cycle = 120 days

• Damaged erythrocytes are removed from the  circulation and destroyed  by phagocytic macrophages in the liver & spleen

• Main function – transport of gases

Describe haemoglobin?

• Oxygen binds to haem group = Oxyhaemoglobin

• Carbon dioxide binds to globin = Carbaminohaemoglobin

What is a full blood count?

Full Blood Count (FBC) Commonly ordered blood test that analyses the number of red blood cells, white blood cells and platelets in a sample.

• For example, to investigate anaemia.

What is erythropoiesis?

• The process of erythrocyte production

How does erythropoiesis work?

• Erythropoietin (EPO) – hormone that controls erythrocyte  production

• ↓ O2 in circulation is detected by kidneys, causing EPO secretion

• EPO can be used to treat anaemia caused by chronic kidney  disease and cancer treatment

 Describe WBC?

• Largest blood cells, contain nucleus

• All leucocytes can migrate out of blood vessels into the surrounding tissues

• Main function is the defence against infectious disease and invasion

• Phagocytosis 

Describe Platelets?

• Approx 150,000 - 400,000 platelets per μL of blood

• Fragments of cells (megakaryocytes) from the red bone marrow

• 2-4μm in diameter

• no nucleus 

• Function - ‘clotting’ or homeostasis - sequence of events initiated to stop bleeding

What are the stages of platelet formation?

• vascular spasm, platelet plug formation, coagulation

Describe blood plasma?

• Pale straw colour 

• Approx. 91.5% water

• Approx. 8.5% solutes

• solutes include proteins (albumins, globulins, fibronogen), nutrients, vitamins, hormones, respitory gases, electrolytes, and waste products

Describe the heart structure and surface landmarks?

• Cone shape 

• Mediastinum 

Anatomical Relations:

• Superior vena cave

• Inferior vena cava

• Ascending aorta

• Descending (thoracic) aorta 

What is the pericardium?

• Pericardium - 2 layers, fibrous and serous (double layer - parietal and visceral), pericardial space with small volume of pericardial fluid

What are two pathologies affecting the pericardium?

• Pericarditatis → inflammation of the pericardium, painful

• Pericardial effusion → excess fluid in the pericardial space

What are the layers of the heart from outermost layer to innermost layer?

1. Epicardium - inner layer of the serous pericardium 

2. Myocardium - cardiac muscle tissue, thickest layer, rich blood supply

3. Endocardium - Smooth layer of endothelial cells, lines chambers and valves

Describe the right atrium?

• Receives blood from:

  • Superior vena cava

  • Inferior vena cava

  • Coronary sinus

Has:

• Separated by the interatrial septum

• Separated from the right ventricle by the tricuspid (right atrioventricular) valve 

• Right auricale slightly increases the capacity of the right atrium 

• Fossa ovalis - remanant of foramen volae (between left and right atria), which closes after birth 

• Foramen ovale is present in the fetus - blood bypasses fetal lungs

Describe the blood flow of the right atrium?

1. Superior vena cava received deoxygenated blood from the head + neck)

2. Inferior vena cava receives deoxygenated blood from the body 

3. Coronary sinus → deoxygenated blood from the coronary circulation 

Describe the right ventricle?

• Separated from the left ventricle by the interventricular septum 

• Separated from the pulmonary trunk by the pulmonary (semi lunar) valve 

• Pulmonary trunk arises from the right ventricle, dividing into left and right pulmonary arteries and takes deoxygenated blood to the lungs 

• Chrodae tendineae - attached to the cusps of the tricuspid valve

• has papillary muscles

Describe the left atrium?

• Receives deoxygenated blood from the pulmonary veins

• Left auricle 

• Biscuspid valve (or Mitral valve)

Describe the blood pathway in the left atrium?

• Left atrium receives blood from the pulmonary veins that is oxygenated from the lungs

  • This is separated from the left ventricle by the bicuspid valve (mitral valve)

• Left auricle - slightly increases capacity of left atrium

Describe the left ventricle?

• Thick muscular wall - thicker than the right ventricle, because the left ventricle has to pump blood further (and at higher pressure) than the right ventricle 

• Separated from the aorta by the aortic (semilunar) valve

• Ascending aorta arises from the left ventricle, taking oxygenated blood to the body

• Has papillary muscles and chordae tendineae

• Separated from the right ventricle by the interventricular septum

Describe the heart valves?

• Open and close according to pressure changes as the heart contracts (systole) and relaxes (diastole)

• Ensures one way flow of blood through the heart

• prevents backflow of blood

Describe the 2 atrioventricular valves?

• Between the atrium and ventricle

• Tricuspid (or Right Atrioventricular)

  • 2 cusps, or leaflets 

• Mitral (Bicuspid) (or Left Atrioventricular)

  • 2 cusps, or leaflets 

• Open when the atria contracts

• Closed when the ventricles contract 

Describe the semilunar valve?

• Semilunar (semi = half, lunar = moon-shaped)

• Each valve is made up of 3 moon-shaped cusps 

• Aortic valve 

• Pulmonary valve

• Open when the ventricles contract 

Aortic valve: between the ……..ventricle and the …….. …………

Pulmonary valve: between the ………… ventricle and ………… ………….

Aortic valve: between the left ventricle and the ascending aorta 

Pulmonary valve: between the right ventricle and pulmonary trunk

Describe blood pressure in the heart?

• Blood pressure is the force of blood pushing against the walls of your arteries 

• Systolic pressure: pumps out blood

• Diastolic pressure: rest between beats 

• Normal blood pressure is typically considered to be around 120/80 mmHg.

  • Blood pressure can vary throughout the day and can be influenced by factors such as stress, physical activity and diet 

Describe the aorta?

• Arises the from the left ventricle

Includes:

• Ascending aorta 

• Arch of aorta 

• Descending (thoracic) aorta 

• Passes through the diaphragm 

• Abdominal aorta 

  • Coeliac trunk 

  • Superior mesenteric artery 

  • Left and right renal arteries

• Divides into left and right common iliac arteries 

Describe the blood vessels?

• Tunica intima (interna) → the innermost layer

• Tunica media 

• Tunica adventitia (externa) → the outermost layer

Describe the atrial supply to the brain?

• Approx. 2% of body weight

• Receives approx. 15-20% of cardiac output

• High oxygen and glucose requirements 

  • Thus, requires constant blood flow

What does a decrease in cerebral flow result in?

• Brief decrease in cerebral flow results in unconsciousness 

  • 1-2 minutes = impairment of neuronal function 

  • >4 minutes = permanent injury 

What is cardiac output?

The amount of blood ejected per minute by the left ventricle into the aorta or by the right ventricle into the pulmonary trunk

What does the venous drainage of the GI tract mean in terms of metastasis?

• Many GI tract malignancies are known to metastasis to the liver

• Malignant cells from most of the GI tract are transported to the hepatic portal circulation and deposited in the liver

What are the 3 forms of circulation?

• Pulmonary

• Systematic 

• Coronary

What is pulmonary circulation?

• the circulation of blood through the lungs

• the right side of the heart is the pump for pulmonary circulation

Describe the pathway for pulmonary circulation

• Right atrium receives deoxygenated blood from the systemic veins (via the inferior vena cava and superior vena cava)

• Right ventricle ejects deoxygenated blood into the pulmonary trunk which divided into left and right pulmonary arteries 

• Blood is oxygenated in the lungs 

• Oxygenated blood is delivered to the left atrium, by the pulmonary veins

Outline the pathway for pulmonary circulation?

Right Atrium → Right Ventricle → Pulmonary Artery → {Blood Oxygenated} → Pulmonary Veins 

What is systematic circulation?

• The circulation of blood throughout the body except the air sacs of the lungs

• The left side of the heart is the pump for systematic circulation

Describe the pathway for systematic circulation?

• Left atrium receives oxygenated blood from pulmonary veins 

• Left ventricle pumps oxygenated blood (via the aorta) to all of the body’s tissue

• Deoxygenated blood is delivered to the right atrium by the systematic veins (inferior and superior vena cava)

Outline the pathway for systematic circulation?

left atrium → left ventricle → aorta → (deoxygenated blood delivered to the systematic tissues) → systematic veins

Describe the coronary vessels?

• provides blood flow to the myocardium

• main arteries are the left and right coronary arteries

• main veins are the cardiac veins and coronary sinus

Outline the coronary circulation?

Ascending Aorta → coronary arteries → capillaries → coronary veins → coronary sinus → right atrium

How are the coronary vessels positioned of the heart?

• Coronary arteries branch from the ascending aorta and encircle the heart 

• During diastole (relaxation), oxygenated blood is propelled into the coronary arteries 

Describe the conduction system?

• Specialised muscle tissues generate and distribute impulses which cause the cardiac muscle fibres to contract
  

Components:

• Sinoatrial (SA) node

• Atrioventricular (AV) node

• Atrioventricular bundle (bundle of His)

• Bundle branch

• Purkinje Fibres

What are sinoatrial nodes?

• Specialised cells within the right atrium

  • Initiates cardiac cycle – the ‘pacemaker’

  • Rate and strength effected by autonomic nervous system & blood borne chemicals e.g. epinephrine

  • Cause atria to contract

What are atrioventricular nodes?

• Found within interatrial septum

  • Action potentials conducted along atrial muscle fibres to  the AV node

  • Initiates the impulse in the atrioventricular bundle bundle

What is the atrioventricular bundle/ bundle of his?

• Specialised fibres running down the interventricular septum

  • Transmit impulse through ventricular system

  • Divide into left and right branches

  • Extend through interventricular septum towards the apex of the heart

What are Purkyne fibres?

• Terminal fibres

  • Conduct the action potential from the apex up through the  ventricular myocardium

  • Ventricles contract

What is an ECG?

• Converts the heart’s lectrical activity → waveform

• Used for diagnosis (12 lead  ECG) & monitoring (3 or 5 lead  ECG)

• Can detect numerous abnormalities

Outline the electrical activity of the heart?

1. Impulse passes Purkinje Fibres

2. Impulse passes bundle of branches

3. Impulse passes bundle bundle of His

4. Impulse arrives in the AV node

5. The sinoatrial node depolarises

Describe the cardiac cycle?

• 1 cardiac cycle = 1 heart  beat

• Consists of systole (contraction) and diastole (relaxation) of both atria and ventricles

• The phases are atrial systole, ventricular systole and relaxation period

1. normal sinus rhythm

2. bradycardia

3. ventricular fibrillation

4. tachycardia

Name the different types of heart diseases?

1. valve disease

2. aneurysm

3. cardiac arrhythmia

4. pericarditis

5. heart failure

6. coronary artery disease

7. cardiomyopathy

Describe DVT?

• Most commonly of the lower limb

• Symptoms include unilateral swelling of the affected limb, pain, erythema

What are risk factors for DVT?

POOSH SIC

• Pregnancy

• Obesity

• Oral Contraceptives

• Smoking

• Hormone replacement therapy

• Surgery

• Immoblity

• Cancer

What is imaging for DVT?

• Compression ultrasound

• Veins containing thrombus do not compress

What are the pulmonary embolism risk factors?

• DVT

• Immobility including  prolonged bed rest, long  distance travel

• Recent surgery

• Pregnancy and the  puerperium

• Smoking

• Oral contraceptives

• Hormone Replacement  Therapy (HRT)

• Obesity

• Increasing age

• Cancer

What is Pulmonary Embolism?

• Known collectively with DVT as Venous Thromboembolism (VTE)

• 3rd most common vascular disease, after Myocardial Infarction and stroke

Symptoms of Pulmonary Embolism?

• Pleuritic chest pain, usually

• worse on inspiration

• Dyspnoea

• Low oxygen saturations

• Syncope

• Haemoptysis

• DVT

Tests for Pulmonary Embolism?

• Arterial Blood Gas (ABG)

• D-Dimer blood test

• Wells score

Treatments of DVT and/or PE

• Anticoagulation drugs

• IVC Filters

• Mechanical thrombectomy

Describe IVC filters?

• Small metal devices placed in the inferior vena cava to trap blood clots and prevent them from travelling to the lungs, helping prevent pulmonary embolism.

What is atherosclerosis?

• Chronic disease of the arteries characterised by a build up of fat,  cholesterol and calcium

• Major cause of coronary artery disease and stroke

• Endothelial damage

• Artery is narrowed

What are the risk factors for atherosclerosis?

SSHHEED POF → CAD, Atherosclerosis

• Sedentary Lifestyle

• Smoking

• Hypercholesterolemia 

• Hypertension

• Excess alcohol consumption

• Ethnicity

• Diabetes

• Poor diet

• Obesity 

• Family history 

Describe Abnormal Aortic Aneurysm?

• Abnormal dilation of the aorta

• May be asymptomatic, may present with referred back or

• abdomen pain, mass in the abdomen which may pulsate

Risk factors of Abnormal Aortic Aneurysm?

(MAATHH)

• Men

• Atherosclerosis

• Age

• Tobacco

• Hypercholesterolemia

• Hypertension

Outline the public health screening for AAA?

• 65 year old males in England

• Aim to reduce AAA related  mortality in men aged 65-74

• Early detection, monitoring and  treatment is crucial in order to  reduce mortality rates from  ruptured AAA

What is coronary artery disease?

Atherosclerosis of the coronary arteries

What are the risk factors of Coronary Artery Disease (CAD)?

SSHHEED POF → CAD

• Sedentary Lifestyle

• Smoking

• Hypercholesterolemia 

• Hypertension

• Excess alcohol consumption

• Ethnicity

• Diabetes

• Poor diet

• Obesity 

• Family history 
  

What are the signs and symptoms of CAD?

• Chest pain (angina pectoris)

• Pain that radiates to the arm, neck, jaw, back or  stomach

• May be described as heaviness or tightness, or indigestion

• Dizziness

• Nausea

• Dyspnoea

• Fatigue (in chronic CAD)

What imaging is used for CAD?

1. Cardiac CT

2. Cardiac MRI

3. Myocardial Perfusion Imaging (MPI) 

4. Coronary Angiography

5. (Echocardiography)

6. PET/CT

What is pericardial effusion?

• Abnormal accumulation of fluid  between pericardial layers

What are some patholgies of the heart?

• Stroke and Transient Ischaemic Attack (TIA)

• Peripheral vascular disease

• Heart failure