Case 15 Flashcards
What is the MABP and how is it calculated ?
Mean arterial blood pressure. Degree of vasoconstriction of arterial bed
MABP = CO x TPR (total peripheral R)
How is blood flow calculated and what is the main vessel of resistance?
Blood flow = perfusion P / vascular resistance
Aterioles have highest R
What is the difference between the systemic and pulmonary circuits ?
Systemic is high P high R
Pulmonary is low , pulmonary artery pressure is 22/10
What is the pressure in the Vena cava ?
0-5 mmHg
What are the JVP and Pulmonary wedge pressures estimates of ?
JVP , estimate of P variation on R side of heart
Pulmonary wedge = LA
What does the area in a PV loop indicate ?
The work done by the heart
What happens in a PV loop after ESV ?
End systolic volume. Mitral valve opens blood into LV so V+P ^ as walls resist filling slightly (bottom left to bottom right)
What occurs in a PV loop after EDV ?
End diastolic volume. Ventricles filled mitral valve closes. systole begins but all valve shut so no vol change P ^ as isovolumetric contraction begins. (bottom right to top right)
What is happening from top right to top left in a PV loop?
Aortic valve opens, ejection occurs rapidly than reduces.
What changes would you see to a PV loop if the ejection fraction was compromised ?
Preload ^ so loop moves right and smaller. The contractility may also decrease.
What is the function of arterial baroreceptors ?
Found in carotid sinus and aortic arch. Respond to stretch to minimise fluctuations in MABP. Send signals to medulla
Where is the initial processing of baroreceptor info in the medulla and where is the resulting parasympathetic output ?
Processing in the NTS (nucleus tractus solitarius)
Para output from nucleus ambiguus
Where are the centres of; defence during stress and thermoregulation ? and circulatory response in exercise?
Hypothalamus
Cerebellum
What is the brief baroreceptor reflex ?
Bp/B vol down , HR ^ , contractility ^ , peripheral vasoconstriction ^ , ^ BP/Vol
Where are the ‘blood reservoirs’ at rest and what is their function during exercise ?
Large veins regulated by SM in walls. CV reserve used in exercise (^ tone)
How does the CV reserve change with age ?
With age and/or HF, sympathetic drive decreases as CO/stress on heart already increased due to compensatory mechanisms.
What reflex is antagonists to Baroreceptor reflex and when is it triggered ?
Bainbridge. Triggered when B vol is high. Stretch receptors at vena cava.
What is the process triggered by rapid IV saline for example ?
Stretches great veins -> ^HR. Shifts blood from congested venous side to arterial side. ^HR by ^RA P due to stimulation of atrial receptors
How does the Bainbridge reflex affect the peripheries and the kidneys ?
Doesn’t initiate peripheral vasoconstriction.
Inhibits vasoconstriction in kidneys -> tachycardia +^GFR due to opening to ^ filtration
How is brain blood flow protected by chemoreceptors ?
Low ppO2 -> sympathetic vasoconstriction to ^ P and HR
What is the fluid distribution intra/extracellularly and what is the composition of blood within these compartments ?
ICF = 15L , ECF = 25L
Blood plasma = 3L ECF
RBC = 2L ICF
What is the dominant cation in the ICF and ECF ?
ICF = K , ECF = Na
Why is Na regulation in ECF important ?
Makes up 95% of solutes (and osmotic P).
Na drops = vomit, diarrhoea
Na ^ = CHF, cirrhosis, hypertension
What are the fx that influence urine production by nephrons and CD ?
glomerular filtration of plasma , tubular reabsorption (proximal absorption of HCO3) and tubular secretion (Distal secretion of H)
What is the formula for GFR?
GFR = Kf (ultrafiltration constant) x Puf (ultrafiltration pressure)
What are the 3 fx of ultrafiltration pressure ?
Puf = Pgc (glomerular hydrostatic P in afferent arteriole) - Pt (capsular hydrostatic P in the lumen) - πgc (blood cooled osmotic P)
What is the normal value of Puf?
10 mmHg
What is the myogenic mechanisms of renal autoregulation of GFR ?
systolic BP ^ -> stretch afferent arteriole -> muscle contraction -> diameter done -> BP falls
What is tubuloglomerular feedback ?
mediator of vasoconstriction (local adenosine) acts on adenosine-1 receptor on afferent arteriole. ^BP -> ^GFR -> less time for Na/Cl/H2O reabsorption -> JGA detection ^ renin release.
What is the RAAS response to dehydration ?
BP down -> JGA ^ renin and angiotensinogen from liver -> AT1 formed goes to lungs -> AT2 via ACE -> vasoconstriction of arterioles and ^ aldosterone so BP ^ and Na/H2O reabsorption ^
What is the effect of the intrarenal PG system ?
Locally acting PGs ^ GFR and decrease Na reabsorption by ^LoH and CD flow.
What is HF In lamen terms ?
Inability of heart to meet body blood requirements through LV systolic dysfunction. Results in activation of compensatory mechanisms
What are the main causes of HF?
Ischaemic heart disease, hypertension, valvular dysfunction, dilated cardiomyopathy
What happens to the sympathetic drive during HF?
It increases to ^adrenaline so HR^ and CO^ in compensation
Px goes on HF drugs, what monitoring needs to take place ?
Follow up every 2 weeks. close monitoring of pulse, BP and renal function. Refer to nurse led clinics. Telemonitoring
What is LCZ696 ?
dual neurohormonal inhibition using Valsartan and Sacubitril to induce hypotension
What is the effect of Sacubitril ?
Inhibits Neprilysin (normally breaks down BNP) so natriuretic peptide levels increase
What are the 3 main causes of absolute Fe def in HF ?
Malnutrition , malabsorption , GI losses
What inflammatory cytokines ^ during anaemia of chronic disease ?
IL-1 , IL-6 , TNF-a
What is the problem with taking aspirin and anticoagulants during IHD ?
Ischaemic heart disease
Can lead to GI blood loos -> absolute Fe def
What is OSA ?
Obstructive sleep apnoea , collapse of pharyngeal airway. Leads to heavy snoring and disrupted sleep
What feedback is lost during HF that results in sleep apnoeas ?
When CO2^/PO2 falls signals normally sent to diaphragm -> contraction -> breathing. This stops in HF
What is apnoea ?
Complete cessation of airflow for over 10 seconds
What is the difference between obstructive and central sleep apnoea ?
Obstructive = thoracic/abdo movements still present Central = no thoracic/abdo movements, unstable feedback of resp system
What is the AHI ?
Apnoea hypoopnoea index; total no events/hour in sleep
5-15 = mild , 16-30 = moderate , 30+ = severe
When is CPAP contraindicated ?
For central sleep apnoea -> poorer px outcomes
^ ejection fraction for OSA
When is LA angioplasty pointless ?
If >50% tissue scarring in target area because the myocardium won’t be viable and the coronary artery will have no useful function
What is the Batista operation ?
Cut open heart, remove scar tissue and mitral valve
How does a ventricular assist device function ?
Plugs into apex of heart, sucks blood out and pumps into the aorta. Used in px with poor prognosis. Most require surgery within 1 year.
What are the +ve effects of resynchronisation ?
Resynchs LV contraction
^6 min walk past, ^QoL, Cardiopulmonary test VO2 max^
Improves LV ESV and LV EF
What are the major causes of non ischaemic cardiomyopathy ?
Ischaemic HD (60%) , cardiomyopathy and hypertension (15%) , valvulopathies (10%)
What is hypertrophic cardiomyopathy ?
wall thickness (septum) >15 mm in 1+ segments causes; myocardial fibrosis , abnormalities of MV. Can’t be explained solely by loading conditions
What is ASH ?
asymmetrical septal hypertrophy. Stiffness requires ^ P to fill up. P comes from atria -> atrial dilation. Tract for blood v small -> velocity of blood ^ , P grad pulls mitral valve toward septum so hole becomes even smaller
How does HCM commonly present ?
Syncope, arrhythmia, baroreflexes, LVOT obstruction. Possible dyspnoea, diastolic dysfunction , AF (stroke) , MR.
How would HCM show on an ECG ?
Sinus rhythm, atrial fibrillation, ST segments , T wave inversion
What is the medical therapy for LVOT obstruction?
(Non dilating b blockers or Verapamil) with disopyramide (a Na channel blocker)
If using b blockers monitor QT
What is alcohol septal ablation ?
Catheter in LAD, inject dye and balloon into septal branch. Then insert alcohol to destroy muscle/tissue and initiate infarct to decrease septal buldge.
What is DCM ?
Dilated cardiomyopathy, cardiac enlargement with decreased systolic function. No primary valve disease or significant CAD.
What is an Epsilon wave and along with T wave inversion of V1-V3 what would it indicate ?
Small positive deflection buried in QRS. May look like an M at the end of QRS.
Arrhythmiogenic RV cardiomyopathy
What is ARVC ?
fibro fatty infiltration, ventricular dilation and hypertrabeculation
What is RCM ?
restrictive cardiomyopathy. Normal cardiac size with decreased systolic/diastolic function and bilateral dilation. Usually from an MI
How does presentation of RCM change between males and females ?
Later in females because protein build up is slowed due to periods. Present post menopause
What is amyloid disease ? What does an ECG show ?
Cardiac deposition of abnormal protein load. Hypertrophy but normal complexes on ECG.
What is the cardiothoracic ratio? What is the normal for adults ?
On a CXR, the ratio of distance between horizontal borders of the heart and the distance between the ends of the rib cage. Normal is 0.5 in adults. May be slightly ^ in kids and athletes.
What is a systolic murmur ?
Heart in ejecting phase. Abnormal sound from closure of tubes or turbulent blood flow eg. aortic valve stenosis or mitral regurgitation.
What is an S4 systolic murmur and what are the risk fx?
Sound proceeding S1 late diastole just before valves (LV) shut due to stiffness/lubrication.
Age, chronic hypertension, genetics.
When is an S3 diastolic murmur heard ?
Early diastolic from rapid chamber filling.
What are the sounds for S3 and S4 respectively ?
S3 = sloshing-ing IN S4 = AT stiff wall
What are crepitations ?
Crackling sound breathing in as the airways ‘pop open’
What is a bruit ?
Abnormal sound in an artery. Possible renal artery stenosis, aortic dissection.
What is delirium ?
Acute cognitive impairment due to another medical condition. Can improve for up to 6 months after.
What is sarcopenia ?
Clinically; Loss of muscle strength
Ageing (1st) and HF (2nd) causes. Deconditioning worsens sx.
What is frailty ?
Accumulation of deficits in multiple organ system over time. More prone to negative outcomes due to decreasing homeostatic reserve.
What is the difference in BP between men and women ?
20-25 healthy male 75 Kg normal BP = 120/80
A women would be around 10 below this.
What is essential hypertension?
Idiopathic (95% of cases). Possible causes; fewer nephrons, impaired renal Na excretion so ANP^, overactivity of RAAS.
How does LVH arise from chronic hypertension ?
Left ventricular hypertrophy. Sacromeres added in parallel to original ones, thickens wall -> CHF with dilatation of the heart. Hypertrophy compromises SV initially then fails -> congestion.
Where does vascular wall thickening occur and why?
Result of ^BP, media of muscular arteries (hyperplasia of muscle and collagen deposition -> stiffness). Overall decreases compliance.
What is hyalinisation ?
cause of renal failure possibly from chronic HT. Proliferation of small BVs and deposition of large proteins, in this case Fibrinogen in media layer of glomerulus and arterial walls.
How do GFR and RAAS effect BP ?
GFR down -> ECF^ -> ^CO (higher preload) -> ^BP
RAAS ^ -> Na reabsorption and ECF increase which follows on to ^BP.
CO is increased through fluid expansion of ECF. How does this happen ?
GFR down, ^Na reabsorption, RAAS^ , Sympathetic drive ^ (nerves stimulate JGA to secrete renin)
What fx affect Na reabsorption in the PCT and DCT ?
PCT = AT2 DCT = aldosterone effect
What substances cause a decrease in CO ?
renal PGs (auto reg of the kidney) and PGE2 inhibit salt and water retention. This reduces ECF volume, decreasing CO.
What is the effect of peptides relative to essential hypertension ?
Peptides inhibit pumps in SM arteriole walls. ^intracellular Na so decreases pumps. This ^Ca causing vasoconstriction and TPR increases.
What are the iatrogenic fx for hypertension ?
Taking; COCP, NSAIDs (^intrarenal PGs so effect kidney filtration) , steroids, chronic vasoconstriction meds
What is Liddle’s syndrome?
^BP in early life due to ^ expression of epithelial Na channel in CD. ^reabsorption of Na. v rare.
What is metabolic syndrome ?
HT associated with obesity and insulin resistance. ^PCT Na/H exchange.
Where is the most resistance in circulation ?
Peripheral ends of the arteriole tree. Site of most damage. Eye tests give good indication of vasculature
How do blood volume pathologies arise ? What happens to the internal disc lamina ?
Repetitive stress from HT changes to medial layer esp SM hypertrophy (tunica media) ^TPR and BP.
Internal disc lamina becomes reduplicated and interrupted. Hyaline degeneration -> glassy eosinophilic material ^ -> rigidity.
How would fibroid necrosis in an artery look histologically?
Wall is bright pink with dark neutrophils.
What is nephrosclerosis ?
Shrinking of glomerular BM (poor perfusion) , hypertrophic and hyaline depositions in afferent arterioles -> sclerosis. Tubes become ischaemic -> atrophy and fibrosis (nephrosclerosis).
Name a diuretic and give a + and - outcome of use ?
Chlorothiazide. Coexistant CCF adjunctive with other agents.
May cause electrolyte/metabolic ADRs and allergies.
What is the first stage of mx in HT?
Confirm persistant HT on multiple occasions. Modify reversible lifestyle fx. Investigate end organ damage (esp heart, kidney). Look at other vascular risk fx eg. plasma lipid profile. Screen for 2ndry HT causes.
What is renal parenchymal disease ?
Loss of vasodilation then retention of Na/H2O leading to ECF ^. Cause of secondary hypertension.
What is Conn’s syndrome ?
adrenal cortex tumour secretes aldosterone no matter regulation. -ve feedback on Renin (decreases) so aldosterone:renin ratio ^. Possible metabolic alkalosis.
What condition would show a normal aldosterone:renin ratio even though aldosterone has ^ ?
Coronary HF, ^aldosterone but no compensation so BP stays ^. RAAS stays active so ratio normal
What is adrenal medulla pheochromocytoma and how would you test for it ?
Adrenal tumour secreting catecholamines. BP spasms up and down quickly. 24 urine test recording catecholamine levels.
What is the difference between the renal parenchyma and the collecting system ?
Parenchyma, functioning kidney that filters blood and makes urine
Collecting system, urine produced by parenchyma then filtered moves urine out of kidney into ureter then into bladder
What is the outline of the Goldblatt experiment ?
clipped kidney hypoperfused (thinks BP down) so ^ renin -> vasoconstriction/BP^. Perfusion restored at higher BP.
Healthy kidney drops renin but no natriuretic response so Na not compensated (mystery). Intrarenal AT2 stays high in healthy kidney.
What are the 3 fundamental features of HF ?
Haemodynamic changes (^plasma vol to try ^CO) , Metabolic effects (decrease coronary flow, ^stress to myocardium) , neurohormonal changes
How is SV maintained through ‘compensation’ ?
Filling pressure increases. Vol ^ early in HF to ^preload and decrease CO.
How does the EDV change over time during compensation?
Over time hearts contractility decreases so EDV at rest ^ to compensate. Smaller window of compensation with exercise.
What is the cause of diastolic HF ?
delayed relaxation and impaired filling. Typically seen in px with cardiac hypertrophy.