Basics of cardiology Flashcards
What separates the right auricle from the right atrium?
Sulcus terminalis
Crista terminalis
Name the structures which form the cardiac borders
Right border - right atrium
Left border - left ventricle, left atrial appendage
Anterior border - right ventricle
Posterior border - left atrium, left ventricle
Superior border - atria and great vessels
Inferior border - right ventricle
Name the structures forming the right cardiac border
Right atrium
Name the structures forming the left cardiac border
Left atrial appendage
Left ventricle
Name the structures forming the anterior cardiac border
Right ventricle
Name the structures forming the posterior cardiac border
Left atrium
Left ventricle
Name the structures forming the inferior cardiac border
Right ventricle
Name the structures forming the superior cardiac border
Atria
Great vessels
Explain coronary arterial dominance
Describes the vessel which gives rise to the PDA
Right dominant ∼ 85% (RCA)
Left dominant ∼ 8% (LCX)
Co-dominant ∼ 7%
When does coronary blood flow peak?
Early diastole
Name the source of the left coronary artery
Left aortic sinus of ascending aorta
Name the source of the right coronary artery
Right aortic sinus of ascending aorta
Name the important branches of the left coronary artery
Left anterior descending artery (LADA)
Left circumflex artery
Name the important branches of the right coronary artery
Right marginal artery
PDA
AV nodal artery
SA nodal artery
Describe the course of the left anterior descending artery
Descends between right and left ventricles on anterior surface of heart in the anterior interventricular sulcus towards cardiac apex
Which structures are supplied by the left anterior descending artery
> 50% of left atrium and ventricle Anterior aspect of the left ventricle Anterior ⅔ of the interventricular septum Anterolateral papillary muscle Cardiac apex
Describe the course of the left circumflex artery
Courses left around the heart in the coronary sulcus towards the posterior aspect, ending before the posterior interventricular sulcus and gives off the left marginal artery
Which arteries supply the anterolateral papillary muscle?
LADA
LCX
Which structures are supplied by the left circumflex artery?
Posterolateral left atrium and ventricle
Anterolateral papillary muscle
SA node ∼ 40%
PDA ∼ 15%
Describe the course of the right marginal artery
Courses along diaphragmatic border
Which structures are supplied by the right marginal artery?
Lateral right ventricle
Cardiac apex
Describe the course of the posterior descending artery
Descends between right and left ventricles on posterior surface of the heart in the posterior interventricular sulcus towards cardiac apex
Which structures are supplied by the posterior descending artery?
Posterior ⅓ of the interventricular septum
Posteroinferior aspect of heart
Posteromedial papillary muscle
Which structures are supplied by the AV nodal artery?
AV node
Bundle of His
Which structures are supplied by the SA nodal artery?
SA node
Which is the most commonly occluded coronary artery?
LAD
The occlusion of which coronary vessel will result in cardiac arrythmias?
Right coronary artery
Where do the lymphatics of the heart drain?
Anterior mediastinal nodes
Tracheobronchial nodes
Discuss the innervation of the heart
Somatic nervous system - phrenic nerve
Sympathetic nervous system - cardiac plexus
Parasympathetic nervous system - vagus nerve
What is the visceral layer of serous pericardium?
Epicardium
What is the endocardium composed of?
Endothelium
Loose CT
Subendocardium
What is the subendocardium?
Loose connective tissue containing cardiac Purkinje cells, veins and nerves
What is the myocardium composed of?
Cardiomyocytes
Fibroblasts
Extracellular matrix
Which nerve is responsible for the sensory innervation of the pericardium?
Phrenic nerve
What germ layer gives rise to the heart?
Mesoderm
What do the endocardial cushions give rise to?
Atrial septum
Interventricular septum
Valves
What does the primitive atrium give rise to?
Trabeculated portions of atria
What does the primitive ventricle give rise to?
Trabeculated portions of ventricles
What does the primitive pulmonary vein give rise to?
Smooth portion of left atrium
What does the sinus venosus give rise to?
Right horn - smooth portion of right atrium
Left horn - coronary sinus
What does the cardinal veins give rise to?
SVC
IVC
What causes a defect in cardiac looping?
Defect in dynein arm of microtubules
What does a defect in cardiac looping result in?
Kartegener syndrome
How do you calculate EF?
SV/EDV
Name the 4 phases of the cardiac cycle
Isovolumetric contraction
Systolic ejection
Isovolumetric relaxation
Ventricular filling
During which phases of the cardiac cycle are all valves open?
None
During which phases of the cardiac cycle are all valves closed?
Isovolumetric contraction
Isovolumetric relaxation
Define chronotropy relative to cardiac physiology
Any influence on the heart rate
Define dromotropy relative to cardiac physiology
Any influence on myocardial conductivity
Define inotropy relative to cardiac physiology
Any influence on myocardial contractility
Define lusitropy relative to cardiac physiology
Any influence on myocardial relaxation
Define bathmatropy relative to cardiac physiology
Any influence on myocardial excitability
Which equation describes the relationship between vascular resistance, the length and radius of the vessel, and the viscosity of blood?
Poisueille equation
Name factors that influence blood flow
Blood viscosity
Blood velocity
Lumen diameter
Blood vessel wall smoothness
What Reynold’s number does laminar flow have?
Low
What Reynold’s number does turbulent flow have?
High
How do you calculate MAP?
⅓ systolic pressure + ⅔ diastolic pressure
OR
CO x TPR
What is a normal pulse pressure?
30–40 mmHg
Name causes of a low pulse pressure
Advanced heart failure
Cardiac tamponade
Aortic stenosis
Shock
Name causes of a high pulse pressure
Exercise Hypothyroidism Aortic regurgitation Anemia OSA
What is the importance of Laplace’s law?
Increased vessel thickness results in decreased wall tension
Differentiate vascular compliance from vascular elastance
Compliance - adapt to change in pressure
Elastance - adapt to change in volume
What is the triad of symptoms in Cushing reflex?
Hypertension
Bradycardia
Respiratory depression
Explain the mechanism of Cushing reflex
↑ intracranial pressure → compensatory constriction of cerebral arterioles → ↓ cerebral perfusion → hypercapnia and acidosis → chemoreceptor mediated sympathetic response → ↑ blood pressure → stimulation of aortic arch baroreceptors → activation of the parasympathetic nervous system (vagus) → reflex bradycardia
What is the atrial reflex also known as?
Bainbridge reflex
What is the atrial reflex?
Atrial distension -> incr HR
What is the diuresis reflex also known as?
Gauer-Henry reflex
What is the diuresis reflex?
Incr BP -> decr ADH
Which chemoreceptors are more responsive to chronic hypoxia?
Peripheral > central
How does carotid massage act to reduce the heart rate?
Stimulating the carotid baroreceptors leads to an increased AV node refractory period
Where is central blood pressure regulation localized?
Solitary nucleus in the medulla oblongata
What are the afferent and efferent pathways of central blood pressure regulation?
Afferent - glossopharyngeal nn (carotid) - vagus nerve (aorta) Efferent - sympathetic - parasympathetic
What causes the release of ANP from atrial cardiomyoctyes?
Increased volume
How is RAAS activated?
Release of renin from the juxtoglomerular cells
What is myogenic autoregulation?
Myocytes in the walls of arteries and arterioles react to changes in blood pressure to maintain constant blood flow in the blood vessels (incr BP -> vasoconstriction)
Which receptors does epinephrine have a greater affinity for: alpha 1 or beta 2?
Beta 2 receptors
How does epinephrine concentration affect adrenergic receptors?
Low concentration - greater effect on beta 2
High concentration - stronger effect on alpha 1
What is the hypoxic pulmonary mechanism?
Hypoxia results in pulmonary vasoconstriction
Define hydrostatic pressure
The pressure exerted by any fluid on the wall of an enclosed space
Define osmotic pressure
The minimum pressure needed to prevent the flow of a solvent across a semi-permeable membrane
Define oncotic pressure
Intravascular osmotic pressure generated by proteins
What are the 4 Starling forces?
Capillary hydrostatic pressure
Interstitial hydrostatic pressure
Plasma oncotic pressure
Interstitial oncotic pressure
How do burns, infections and toxins cause edema?
They affect vessel permeability
At what point is the JVP elevated?
> 4cm
How do you estimate the CVP?
JVP + 5cm
Which side should you assess the JVP and why?
Right side
More direct path to SVC
What is the reference range of the CVP?
4-10 cm H20
What are signs of an elevated JVP?
Incr JVP
Kussmaul sign
Hepatojugular reflux
Name causes of elevated JVP
Right sided HF Fluid overload Tricuspid dysfunction Pericardial effusion Constrictive pericarditis Cardiac tamponade SVC syndrome Pulmonary hypertension
Name the components of the JVP waveform
a wave c wave x descent v wave y descent