Cardio Flashcards
What is the endocardium?
Inner most layer of heart
Lines heart chambers
Made of simple squamous epithelium on basement membrane
Forms valves
What is the myocardium?
The middle layer of the heart, thickest Made of cardiac muscle Striated with lots of mitocondria Rich capillary bed Myocytes connected by intercalated discs
What are intercalated discs?
Complex junctions that connect myocytes Desmosomes >Binds myocytes together Gap junctions >Electrical communication >Essential cor o-ordination oc cardiac cycle
What is the epicardium?
Outer layer of heart
Made up of connective tissue and BM with simple squamous pithelium
>Epithelium same as visceral layer of serous pericardium
Contains main branches of coronary arteries
What are the features of the heart valves?
Control direction of blood
Cusps - thin structures derived from endocardium
Work passively
Chordae tendineae and papillary muscles prevent valve failure
What are the heart valves?
Semilunar - Pulmonary /Aortic
Atrio-ventricular - bicupsid (mitral) / tricupsid
What is the cardiac skeleton?
Connective tissue that provides structural support to the heart
Provides electrical insulation
What are the coronary arteries?
Left and right - have smaller subdivisions
Found in epicardium
During systole aortic sinuses shielded by aortic valve cusps
In diastole blood can then enter
What makes up the cardiovascular system?
Heart
arteries, veins, capillaries
Lymphatics
What are the layers of a blood vessel?
Tunica intima >simple squamous Epithelium + BM + epithelium Tunica media >Muscle - smooth or elastic Tunica adventitia >Connective tissue
What are the types of arteries?
Elastic
Muscular
Arterioles
What are elastic arteries?
For large conducting arteries - like Aorta
Work as a pressure reservoir
Stretched during systole, and during dystole they recoil maintianing pressure on blood
Due to elastic fibres in tunica media in laminae
What are muscular arteries?
For distribution of blood to regions - like femoral
No elastic laminae, but smooth muscle cells
Do have elastic fibres in internal elastic lamina and external elastic lamina
>Found underneath epithelium and between Tunica media and adventitia
What are arterioles?
Terminal branches before capillaries
No internal elastic lamina
Only 1 or 2 layers of smooth muscle in tunica media
And no tunica adventitia
They control blood flow to capillary beds
And control systemic blood pressure
What are capillaries?
Main site of echange for nutrients and gases
Thin walled with only tunica intima
Have pericytes that help control bloof flow
What are pericytes
an incomplete layer of cells surrounding basment membrane of capillaries
Have contractile properties
What are the three types of capillary?
Continuous
Fenestrated
Discontinuous
What are the features of continuous capillaries?
Can control what is exchanged in and out
Material must pass through cell of between cell
Selective transport mechanims
Foundin muscle
What are the features of fenestrated capillaries?
Have pores in the lining (fenestrations)
Can be with or without protein diaphgrams (which filter moecules by weight or charge)
Found in endocrine glands/renal corpsucle
What are the features of discontinuous capillaries?
Have gaps between endothelial cells (and basement membrane)
Allow free passage of fluid and cells
Found in Liver, spleen, bone marrow
What are sinusoids?
Large diameter discontinuous capillaries
Found where large amount of exchange takes place
T. intima contains phagocytic cells
What is the structure of a vein?
Thin T intima IEL/EOL thin or absent T mediat thin or absent T adventitia made of collagenous tissue Have valves to prevent backflow
What is the difference between superficial veins and deep veins?
Superficial are thick walled and have no surrounding support
Deep are thin walled and have surrounding support from deep fascia and muscle
What is teh lymphatic system?
Drains tissue fluid lost from capillaries
Drains into venous system
Nodes found alongside major veins/artery origins
Valves direct flow
What are lymph capillaries?
Blind ended capillaries lined by vey thin epithelium
No fenestations
Absent basal lamia
Lumen contained via negative hydrostatic pressure
>has collagenous filaments linking to surrounding tissue to keep lumen open
No red blood cells enter
Where is the blood/lymphatic cupply of blood vessels?
Blood - vasa vasorum in T adventitia
Lymphatics in T adventitia
What is the cardiac cycle?
Diastole
Atrial systole
Ventricular contraction
Ventricular ejection
What is the pressure volume loop?
A – ventricular diastole + filling sees a gradual increase in volume and pressure.
B – mitral valve closes and the ventricle contracts, pushing pressure up rapidly.
C – Aortic valve opens and the ventricle is still contracting increasing its pressure, decreasing volume.
D – Aortic valve closes and the ventricle relaxes causing a rapid decrease in pressure.
What is the phonocardiogram?
Should hear mitral and tricupsid valves closing together
Then a little later tha aortic + pulmonary closing
“lub-dub” extra hear sounds can be heard in pathology
Why is cardiac muscle unable to exhibit tetanus?
Has a longer refractory period than skeletal muscle
Means that when last contraction is ending, new one begins
Stops tetanus from occuring
What affects electrical activity of the heart?
Temperature Calcium plasma levels hyper=tachycardia + increased contraction, vice versa Potassium serum levels Drugs >CCBs, >Cardiac glycosides
What is the conducting system of the heart?
SAN through atria
AVN
Through bundle of his
Through purkinje fibres
What do the waves on an ECG correspond to?
P - atrial depolarisation
QRS - corresponds to ventricular depolarisation
T - ventricular repolarisation
Where are the ECG limb leads placed?
Right wrist
left wrist
Left leg
Placed on right leg but used to earth
What is the PR interval?
The time ti takes from atrial depolarisation to ventricular depolarisation
What do the precordial leads view?
Gives same information, however in the transverse plane
How large should a square on ECG paper run?
5mm - 0.2 seconds
I.e 30 squares to a minute
What is a STEMI?
ST elevated myocardial infarction (worse than if it didn’t exist)
What is the normal range for the PR interval?
0.12-0.2 seconds
What is the normal range for the QRS interval?
no more than 0.12 seconds
What is the normal range for the QT interval?
0.42 seconds
What HR is normal, bradycardic, tachycardic?
Less than 60 = bradycardic
60-100 normal
Above 100 = tachycardic
What are starling’s forces?
Capillary hydrostatic pressure vs ISF hydrostatic pressure
Plasma osmotic pressure vs ISF osmotic pressure
Net filtration pressure = (Pc - Pif) - (piP - piIF)
What is darcy’s law?
Flow = pressure/resistance
What is poseuille’s law?
Resistance is proportional to length of tube * the viscosity of the fluid /radius
What determines mean arterial pressure?
Cardiac output * total peripheral resistance
How is MAP controlled extrinsicly?
Neural control through sympathetic nerves
Hormonal control through adrenaline
>Both constriction and dilation, dependent on tissue
Angiotensin
Vasopressin
All above are constriction
ANP?BNP - arterial dilation
What are the intrinsic mechanisms for controlling MAP?
Metabolic driven (to “flush”)
Pressure autoregulation
Reactive (due to occlusion)
Injury response
What contributes to venous return?
Gravity skeletal muscle pump respiratory pump venomotor tone systemic filling pressure
What is the vasalva maneuvre?
Forced expiration against a closed glottis
Activates baroreceptor reflex due to decreasing venous return momentarily
What are the signs of hyperlipidaemia?
Corneal arcus Tendon xanthomata Xanthelasmata Family history Biochemical evidence
What is virchow’s triad?
Risk factors for thrombosis
Changes in blood vessel wall
Changes in blood constiuents
Changes in pattern of blood flow
How do beta blockers help myocardial demand?
Decrease heart rate
Decrease contracility
Decrease systolic wall tension
Thus decrease CO/BP
What is the rebound phenomena?
Sudden cessation of beta blocker therapy may precipitate myocardial infarction
What are the contraindications fo beta blockers?
Asthma Peripheral Vascular Disease >Relative contraindication Raynauds Syndrome Heart failure >Those patients who are dependent on sympathetic drive Bradycardia / Heart block
How is HR regulated?
Sympathetic - increases
Parasympathetic - decreases
Both act on SAN
What is afterload?
Afterload is the load against which the muscle tries to contract
Set by arterial pressure
In turn determined by TPR (inversely proportional)
How is stroke volume affected by calcium + infacrction + barbituates?
Hypercalcaemia - increaes
Hypocalcaemia - decreaes
Infacrction - decreaes
Barbituates - decreaes
What are the types of CCBs?
Rate limiting
Vasodilation
How do you treat an ischaemic stroke?
Ateplase within 4.5 hours
After confirmed on CT head
What is secondary prevention for a stroke?
Clopidogrel
Or aspirin + diprydamole
Statins
What are the common sites for varicose veins?
Long and short saphenous veins
What are the S&S of varicose veins?
Cosmesis Localised or generalised discomfort in the leg Nocturnal cramps Swelling Acute haemorrhage Superficial thrombophlebitis Pruritus - itching Skin changes
When should you treat varicose veins?
Superficial thrombophlebitis
Signs of chronic venous insufficiency
Bleeding
How do you treat varicose veins?
Surgery High tie, stripping, multiple stab avulsions Injection (sclerotherapy) Minimally invasive procedures Compression Conservative (may include compression)
What is the presentation of chronic venous insufficency?
Ankle oedema Telangectasia Venous eczema Haemosiderin pigmentation Hypopigmentation “atrophie blanche” Lipodermatosclerosis Venous ulceration
What is the pathogensis of CVI?
Venous hypertension
Venous engorgement and stasis
Imbalance of Starling forces and fluid exudate
Often due to standing still
Or high AVP
What is a leg ulcer?
breach in the skin between knee and ankle joint, present for over 4 weeks
How do you treat CVI?
compression therapy
EXCLUDE ARTERIAL DISEASE
Dressings- non-adherent dressings
if painful- hydrocolloid/ foam dressing
Exercise – calf muscle pump
What are the causes of lymphodema?
Primary: >Congenital >Praecox >Tarda Secondary >Malignancy >Surgery (Radical mastectomy; groin/axillary dissection) >Radiotherapy >Infection (Filariasis/tuberculosis/pyogenic)
What abnormalities is downs associated with?
Atrioventircal septal defects
Duodenal atresia
What abnormalities is turner syndrome associated with?
coarctation of aorta
short stature
gonadal dysgenesis
puffy hands
What abnormalities is nooan syndrome associated with?
Pulmonary stenosis
Short stature
neck webbing
cryptorchidism
What abnormalities is 22q11 deletion syndrome associated with?
C ardiac malformation A bnormal facies T hymic hypoplasia C left palate H ypoparathyroidism
What abnormalities is williams syndrome associated with?
Aortic stenosis (supravalvar) Hypercalcemia 5th finger clinodactyly characteristic face cocktail party manner
What abnormalities is marfansyndrome associated with?
Connective tissue disorder
Mitral valve prolapse
Pneumothorax!
What is a true aneurysm?
Weakness and dilation of vessel wall - include all layers Associated with: Hypertension Atherosclerosis Smoking Collagen abnormalities (Marfan’s) Trauma Infection (mycotic/syphillis)
What is a false aneurysm?
Rupture of aortic wall
Haematoma contained by adventitial layer or surrounding soft tissue
How does a false aneurysm present?
Thrill
Bruit
Pulsatile mass
Ischaemia
Rupture
How does a thoracic aneurysm present?
shortness of breath or even heart failure (AR)
dysphagia and hoarseness (ascending aorta, chronic)
Sharp chest pain radiating to back –between shoulder blades –Possible dissection!
Pulsatile mass
Hypotension
What are the risk factors for aortic dissection?
Hypertension
Atherosclerosis
Trauma
Marfan’s syndrome
What is takayasu’s artertitis?
Granulomatous vasculitis Affects women more than men Presents with stenosis, Thrombosis Aneurysms Renal artery stenosis Neurological symptoms
What is a bicupsid aortic valave?
Most common congenital abnormality Prone to stenosis +/- regurgitation Associated with: coarctation Abnormal aorta (reduced tensile strength) Prone to aneurysm/ dissection Monitor with echo/ MRI
What are the signs of coarctation?
Cold legs
Poor leg pulses
If before left subclavian artery:
>Radial – radial and RIGHT radial-femoral delay
If after left subclavian artery:
>No radial- radial delay
>Right and left radio-femoral delay
What are the symptoms of chronic limb ischaemia?
Intermittent claudication
“Critical limb ischaemia”
Rest pain
ulceration & gangrene (wet/dry)
