Formative Flashcards
What forms the left border of the heart?
Left ventricle
How do you measure the width of the heart as a proportion to width of the chest?
How do you interpret this?
ratio of widest measurement of heart to width of inner aspect
of rib cage at widest point on a PA (posterior-anterior radiograph)
Anything over 50% suggests cardiac enlargment
What are some reasons why the heart shadow might become enlarged on chest xray
dilated left ventricle
ventricular hypertrophy
pericardial effusion
What is cardiac tamponade?
Build-up of blood or fluid in the pericardial space which
compresses the heart
In a patient with cardiac tamponade, why would cardiac output fall?
What would you do to improve the clinical situation?
fall in cardiac output because the outer fibrous layer of pericardium
is inelastic therefore pressure increases in the pericardial sac
restricts filling of the heart
remove blood or fluid by pericardiocentesis
Which artery is the Anterior interventricular artery (Left anterior descending artery) a branch of?
Which area of the heart does it supply?
What would happen if there was a thrombosis in this artery?
Left coronary artery
Supplies the anterior aspect of both ventricles and the
interventricular septum
Myocardial infarction of the anterior aspect of the heart
Describe the series of changes that occur in the arterial wall to cause arterial occlusion
atheromatous plaque forms rupture of plaque thrombus forms thrombus occludes artery leads to MI if coronary artery involved
NOTE:
It is the thrombus or embolus (part of thrombus which breaks off) which
occludes the artery, not the atheromatous plaque
What are the typical symptoms experienced by a patient with MI?
Central crushing chest pain
which may radiate to arm or neck
Explain why a thrombus in the right coronary artery is more likely to cause rhythm disturbance
Right coronary artery supplies SA node (in 60% of people)
or supplies AV node in most people (80%)
What is the function of the cordae tendinae
Prevent the mitral valve inverting during systole
If the mitral valve is incompetent (failure to close properly), what will happen to the flow of blood in systole?
What would you hear on auscultation of the heart?
Incompetence causes blood to be regurgitated back into left
atrium
pansystolic murmur or systolic murmur
If the mitral valve is stenosed (difficult to open), what would happen to the flow of blood in diastole?
What would you hear on auscultation of the heart?
Stenosis would cause turbulent flow across valve
Mid-diastolic murmur
Describe how, anatomically, the heart is supported in the mediastinum
The heart is supported within the pericardium which has two
components:
fibrous pericardium
serous pericardium
visceral layer
parietal layer
or double layer of serous pericardium with pericardial cavity
What collection of defects are seen in Tetralogy of Fallot
Ventricular septal defect
Right ventricular outflow obstruction
Overriding aorta
Right ventricular hypertrophy
Would a patient with Tetralogy of Fallot be cyanosed & why?
Yes, because there is a right to left shunt, bypassing the lungs
What forms the right border of the heart?
Right atrium
Name the structure in the heart responsible for the initiating electrical
activity in the heart and describe its location.
SAN
RA, where SVC enters
Explain why the structure of arterioles makes them high resistance
vessels which can also vary their resistance?
Thick smooth muscle layer
Narrow lumen
= high resistance
TheGPwishestoprescribeadrugwhichwilllowerthepatient’sblood
pressure by causing relaxation of vascular smooth muscle cells in
peripheral vessels. Name two possible classes of drugs which could be used.
L-type calcium channel blockers
Alpha 1 adrenoceptor antagonists
(ACE inhibitors also relax vascular smooth muscle, but this in not their main effect of reducing angiotensin II levels)
Which statement below best describes the action of α1adrenoreceptors?
A α1adrenoreceptors are present on the heart and activation
increases the force of contraction
B α1adrenoreceptors are present on the heart and activation
increases the force and rate of contraction
C α1adrenoreceptors are present on the heart and activation
decreases the rate of contraction
D α1adrenoreceptors are present on peripheral blood vessels and
activation causes constriction
E α1adrenoreceptors are present on peripheral blood vessels and
activation causes dilatation
D
From your knowledge of the nervous system which of the answers below
best describes the role of acetylcholine as a neurotransmitter?
A Acetylcholine activates nicotinic receptors but inhibits muscarinic
receptors.
B Acetylcholine acts on muscarinic receptors at the neuromuscular
junction and at the parasympathetic postganglionic to effector cell
synapse.
C Acetylcholine acts on muscarinic receptors at the neuromuscular
junction and at the preganglionic synapse of both branches of the
autonomic nervous system
D Acetylcholine acts on nicotinic receptors at the neuromuscular
junction and muscarinic receptors at the preganglionic synapses of both
branches of the autonomic nervous system
E Acetylcholine acts on nicotinic receptors at the neuromuscular
junction and the preganglionic synapses of both branches of the
autonomic nervous system
E
describe the abnormality you would see on
the ECG of an individual with first degree heart block
Elongated P-R interval
Where is the conduction problem likely to be located in heart block?
Between atria & ventricles
At AVN or Bundle of His
What is the difference between second degree heart block and third
degree heart block (AV block)?
Second degree:
Intermittent failure of conduction between atria & ventricles
Not all P waves followed by QRS complex
Third degree:
Complete failure of conduction between atria & ventricles
No relationship between timing of P waves and QRS complex
What would you expect to happen to the heart rate of an individual
with third degree heart block? Explain your answer.
Bradycardia
Ventricles create own rhythm but depolarise much slower
Briefly describe how the normal ventricular septum forms
Muscular portion:
Grows up from Ridge from floor of ventricles to meet endocardial cushions
Membranous portion:
Formed by connective tissue of endocardial cushions
Grows down to fill foramen
Most prone to anomalous development
Which part of the ventricular septum is Most prone to anomalous development
Membranous part
Give some causes of a left to right shunt
Ventricular septal defect
Atrial septal defect
Patent ductus arteriosus
(Not PFO; higher left ventricular pressure pushes it closed: not a true septal defect)
Is a patient with a ventricular septal defect likely to be cyanosed? Very briefly explain your reasoning.
No
No mixing of deoxygenated blood with oxygenated circulating around systemic system
In a patient with a ventricular septal defect, Howwillthepressureinthepulmonaryarterycomparetothatofnormal (Answer one of lower, higher or same)
Higher
More blood flowing from left to right ventricle
Increases pressure in pulmonary circulation
Whatwouldtheheartsoundsbelikeonauscultationofa patient with mitral stenosis and why?
Diastolic murmur
Blood flowing through narrowed valve during diastole
Which heart sound is associated with closing of the mitral valve and
when in the cardiac cycle would it close?
S1
Start of ventricular systole
Where in the precordium is the mitral valve best heard?
4th or 5th left intercostal space, mid-clavicular line
Explain briefly why a patient with mitral stenosis is likely to develop pulmonary oedema.
Increase in LA pressure = increased pressure in pulmonary veins
Increased pulmonary capillary hydrostatic pressure
Excess filtration of fluid out of capillaries
Oedema
Briefly state why atrial fibrillation might develop as a result of chronic
mitral valve stenosis and what type of drug might you need to consider if
she develops atrial fibrillation in order to prevent a potentially serious
complication?
Stretch of LA = damage to fibres
Fibrosis = re-entry circuits develop
Anticoagulant: Warfarin
AF = increased risk of thrombosis travelling to systemic circulation
What changes in heart function would be seen in a patient with Tetralogy of Fallot of left untreated?
Right heart failure
NOTE:
The outflow tract obstruction makes it harder for the right ventricle
to pump blood to the lungs. This leads to right ventricular
hypertrophy and can ultimately lead to right ventricular heart
failure.
