PHTY208 Lecture Notes - Lecture 11: Ischemia, Hypokinesia, Endocarditis
Disorders of cardiac conduction and rhythm
• Introduction
o The heart is a muscle that can spontaneously generate action potentials
• This can result in the excitation and contraction of muscle fibres throughout
the myocardium
• These electrical impulses spread through the body and can be read by ECG
o Usually, doctors can tell whether a person has a heart or blood vessel disorder on
the basis of the medical history and the physical examination
o Diagnostic procedures are used to confirm the diagnosis
• Cardiac diagnostic techniques
o Bedside
• History - Otaiig a edial history is always the first "test
▪ Heart problems often produce no symptoms until very advanced
▪ Such as palpitations and sensations of extra or missing heart beats
correlate poorly with relative heart health vs disease
• Auscultation - employs a stethoscope to more easily hear various normal and
abnormal sounds
o Lab
• Blood tests
▪ Blood obtained by venipuncture
▪ Determine the presence of damage to the myocardial
• Tests include
▪ Lipid levels
▪ Homocysteine
▪ C-reactive protein
▪ Blood sugar control
▪ Myoglobin
▪ Creatine kinase
▪ Troponin
▪ Brain-type natriuretic peptide
o ECG/EKG
• A 12 lead recording, recording the electrical activity in three planes
• The ECG allows observation of the heart electrical activity by visualising
waveform
• Observing the PQRST morphology
• Rhythm abnormalities can also be visualised as in slow heart rate bradycardia,
or fast heart rate tachycardia
• The procedure is totally harmless, painless and inexpensive
o Holter monitoring
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• Small, portable monitoring device
▪ Continuous ECG is recorded on a magnetic tape recording while the
patient conducts normal daily activities
▪ Used for suspected frequent rhythm abnormalities, especially ones the
wearer may not recognise by symptoms
▪ They are more expensive than event monitors
▪ Long period of time
o Event monitoring
• Similar to the Holter monitor in that it also records the electrical activity of
the heart while patient goes about usual daily activities
• Can be used for a longer period of time than a Holter monitor
▪ Usually a month
▪ There are several different types with different capabilities
▪ When the wearer presses a button records for a short additional period
o Chest x-ray
• A CXR involves radiation to the body though the level is just minimal
• A pregnant women need special precaution and shielding of the foetus
• The CXR gives us information about
▪ Size and the configuration of the heart and the great vessels
▪ Lung fields and vessels.
• It is a routine cardiac investigation procedure with very low radiation
exposure.
o Echocardiography
• Diagnostic procedure for studying the structure and motion of the heart
▪ Useful in evaluating structural and functional changes in a variety of
heart disorders
• Excellent spatial resolution
• Useful in the diagnosis and grading of the severity of
▪ Valular and congenital heart diseases
▪ Endocarditis
▪ Heart chamber movement and hypokinesia
▪ Pericardial effusion
▪ Cardiac tumours
• Trans-oesophageal
▪ Ultrasound probe into the oesophagus
▪ The patient will need to be under light sedation
▪ Better image of the heart as the ultrasound beam do not need to pass
through the skin, fat and lung heart
▪ Particularly useful for the imaging
• Valves of the heart, the aorta and septal defects
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• Intravascular ultrasound
▪ Catheters attached to computerised ultrasound
• Visualise the lumen and the interior wall of blood vessels
o Exercise stress testing
• The speed and slope of the treadmill will increase gradually in stepwise
fashion in order to test the function of the heart
• Monitoring with ECG, blood pressure and heart rate
• Useful for the diagnosis of
▪ Coronary artery disease, post myocardial infarction risk stratification
and exercise induced arrhythmia
• Radionuclide can be used to demonstrate areas of perfusion abnormalities
• Maximal stress test
▪ Level of exercise is increased until the patient heart rate will not
increase any higher, despite increased exercise
o Cardiac catheterisation
• Diagnostic procedure in which a catheter is introduced into a large vein or
artery and to the heart
• Used to obtain
▪ Information about the structure and function of the heart chambers,
valves, and the great vessels
• Pressure gradients
• Angiography
▪ X-ray visualisation of internal anatomy of heart and blood vessels after
introducing a radiopaque substance (contrast medium)
▪ Promotes imaging of internal structures that are otherwise difficult to
see on X-ray film
• Substance is injected into an artery or a vein
o Electrophysiology
• Catheter with electrodes probing the inside of the heart,
• Measures
▪ Conduction pathways and electrical activity
▪ Timing of the electrical impulse
▪ Cause of the arrhythmia
▪ Sites of the abnormal impulse formation, re-entry circuits or accessory
pathways
o Magnetic resonance imaging
• Use of strong magnetic field and radiofrequency waves to produce imaging
that is valuable in providing images of the heart, large blood vessels, brain,
and soft tissue
▪ Used to examine the aorta, to detect masses or possible tumours, and
pericardial disease
▪ Can also show the flowing of blood and the beating of the heart
o Positron emission tomography (PET)
• Computerised x-ray technique that uses radioactive substances to examine
the blood flow and the metabolic activity of various body structures, such as
the heart and blood vessels
▪ Patient is given doses of strong radioactive tracers by injection or
inhalation
▪ Radiation emitted is measured by the PET camera
o Computer axial tomography
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Document Summary
Size and the configuration of the heart and the great vessels. Substance is injected into an artery or a vein: electrophysiology, catheter with electrodes probing the inside of the heart, measures, conduction pathways and electrical activity, timing of the electrical impulse, cause of the arrhythmia. X-ray density: cardiology uses are growing allowing us to make cardiac studies in just a few seconds. Images are reconstructed using algorithms and software: cardiac conduction system, the cardiac conduction system, controls rate and direction of electrical impulse conduction in the heart. Impulses are generated in the sa node, which has the fastest rate of firing, and travel to the purkinje system in the ventricles. Indications for treatment: what is the cause, are there any symptoms of hypoperfusion (dizziness, chest pain, do not exercise. Fever or infection: pain, anxiety, haemorrhage or shock, cardiac failure, pneumothorax, pulmonary embolism (pe, respiratory distress, medications. Indications for treatment: what is the cause.
