Cardiology - Congenital Heart Disease and HTN Flashcards
When is the CDV system first developed
By 3rd week - diffusion no longer supplies needs of embryo
Formation of primitive blood vessels
How do primitive blood vessels form
In two ways - vasculogenesis and angiogenesis
Vasculogenesis
Blood vessels arise from assembly of angioblasts to form blood islands
Vessels fuse together to form vascular network
Where does blood vessel formation start
In extraembryonic mesoderm
Mesenchymal cells differentiate into angioblasts
Blood island formation
Angioblasts aggregate forming masses and cords
How are the primitive blood vessels formed
Cavities form within blood islands and endothelial (angioblast) cells surround these cavities and form endothelium
When are the heart and great vessels formed
3rd week in cardiogenic region
Great vessels in embryo
Paired longitudinal endothelial lined vessels primordial heart tubes and dorsal aortae
When is the primordial CDV system formed
When primitive blood vessels are joined, connecting umbilical vessels
Development of Primary Heart Field
Progenitor heart cells migrate to splanchnic mesoderm
Initial forms horseshoe-shaped clusters of cells
What does the PHF become
Atria, LV and most of LV - rest of heart comes from 2’ heart field
Formation of primitive heart tube
Single tube w/ aortic and venous poles
The heart tube sprouts aortic arch vessels from the (aortic) outflow region
Endocardium w/ mesenchyme around it differentiates into the myoepicardial mantle
Ultimately forms myocardium and epicardium
When does the heart start beating
By 22 days
How does blood enter the primitive heart
Via 3 main veins into the sinus venosus
Cardinal veins
Vitelline vein
Umbilical vein
How does blood leave the primitive aortic sac
Via aortic arches –> brachial arches —> dorsal aortae
Umbilical artery
Vitelline artery
Truncus arteriousus
Common arterial trunk - aortic arches
How is the aortic sac formed
Distal ends of aortic arches dilate
6 paired aortic arches
In which direction do aortic arches develop
Cranial to caudal - ultimately 5 paired, I - VI (not V)
What doe the aortic arches supply
Brachial arches
When does septation occur
4th week to end of 5th weeks
Heart tube undergoes partitioning into 4 chambers
Process of septation
AV partitioning and cuspid valve formation
Atrial partitioning - spetum primum and septum secundum
Ventricular partitioning
When does the interventricuiar septum close
End of 7th week
Most common type of birth defects
Congenital heart defects
Septal defects
Where theres a hole between 2 chambers
Transposition of the great arteries
Where the pulmonary and aortic valves and the arteries connected and have swapped positions
Most common cyanotic heart defect
Tetrology of Fallots
Cause of blue baby syndrome
Ventricular Septal Defect
Defect opening between 2 ventricles on its superior aspect
Pulmonary stenosis
Narrowing of RV outflow tract, and or just below the pulmonary valve
The degree of stenosis varies - primary determinant of symptoms and severity
Overriding aorta
Biventricular connection of aortic valve above the VSD and connected to both LV and RV
The degree to which the aorta is attached to the RV is referred to as its degree of ‘override’
RVH
RV hypertrophy
RV is more muscular than normal to deal w/ increased obstruction to RVOT, results in characteristic boot-shaped appearance on CXR
Anatomical abnormalities seen in Tetralogy of Fallots
VSD
Pulmonary stenosis
Overriding aorta
RVH
Why does Tetrology of Fallot result in R to L shunt
Mixing of oxygenated & deoxygenated blood in LV due to VSD
Outflow of the mixed low oxygenated blood from both ventricles through aorta because of pulmonary stenosis
What is CHD
Any structural heart abnormality that is present from birth
Epidemiology of CHD
Approx 1% of live-born infants
Palliated, never cured
Commonest lesions in CHD
ASD
VSD
CoA
ToF
What does mx of CHD depend on
Physiology at the time
Normal foetal circulation
High pulmonary vascular resistance in utero
PVR decreases rapidly at. birth, then progressively over 4-6 wks
Arterial duct closes at birth
Oval foramen flap closes w/ increased LA pressure
What does IV PGE2 do to the arterial duct
Keeps it open - given in PDA
What happens with closure of arterial duct and atrial communication at birth
Decreased PVR
RV systolic pressure
RA pressure
Features of ASD
Pre-tricuspid shunt
High pulmonary flow
R heart dilatation - incl RA, RV and pulmonary artery
Presentation and symptoms of ASD in children
Incidental murmurs Recurrent pneumonia Poor growth FTT Exercise intolerance Fatigue
Presentation and symptoms of ASD in adults
Paroxical embolus Stroke Exercise intolerance Recurrent pneumonia Atrial arrhythmia Tricuspid regurgitation, HF, pulmonary HTN
ASD - CXR signs
Cardiomegaly
Dilation of RA and/or RV
Prominent main pulmonary artery
Increased pulmonary vascular markings
Signs of ASD in adults
Prominent RV impulse
Soft, ejection systolic murmur - pulmonary flow murmur
Widely split, soft S2. Fixed in all stages of in/expiration
Indications for closure of ASD
Symptomatic
RA and RV enlargement
Systolic PA pressure < 50% systemic pressure
PVR < 1/3 SVR
What does the feasibility of ASD device closure depend on
Defect size
Anchoring ‘rims’
Features of VSD
Ventricular level shunt
High pulmonary blood flow - pulmonary artery dilatation
L heart dilatation - LA and LV
Presentations and symptoms seems in large VSDs
Frequent chest infections Exercise intolerance Fatigue HF Pulmonary HTN
Indications of VSD closure
Symptomatic
LA & LV enlargement
Systolic PA pressure <50% systemic pressure
PVR < 1/3 SVR
Usually surgical process done early in childhood
Main complication from small VSD
IE
Endothelial damage from aberrant jet streams and turbulent flow
Where might IE vegetations appear in small VSD pts
At tricuspid valve
Opposite or around defect
On aortic valve
Prevention of endocarditis in VSD pts
Good dental hygiene - best
Avoid tattoos and piercings
Prophylactic abx for HIGH-RISK CHD only
High-risk CHD requiring prophylactic abx for IE
R to L shunts (cyanosis)
Valve replacements
Previous endocarditis
Main long-term complications of large VSD shunts
Pulmonary HTN 2’ to c/c high pulmonary blood flow
Once pulmonary vasc resistance > SVR, shunt across any communication reserves (atrial, ventricular or duct)
Problems seen in Eisenmerger syndrome
Polycythaemia Fe deficiency Acne, gout, hypertrophic polyarthropy High pregnancy risk - mustn't get pregnant Paradoxical embolus at IV sites Arrhythmia risks
What is CoA associated with
Bicuspid aortic valve
VSDs
What is CoA associated with
Bicuspid aortic valve
VSDs
Longterm outcome of CoA
Residual CoA
Aneurysmal dilatation
Aortopathy
Surgical mx of CoA
End to repair (resection)
L subclavian flap repair (neonate)
Coarctation stent in preferred for adults
Balloon angio
Resection for CoA
Constricted section of aorta removed
L subclavian flap repair for CoA
Subclavian artery is used as a flap to enlarge the constricted parts of the aorta
Definitive surgery for ToF
Within 1st year of life - RVOT enlargement, patch closure of VSD, patch enlargement of PA
Residual lesions after surgery for ToF
Pulmonary regurgitation
RVOT stenosis
Branch PA stenosis
RV dysfunction
ToF follow up to monitor RV dysfunction
Clinical signs and symptoms MRI Catheterisation CXR ECG & Holter CT CPEX Echo
Simple predictors of maternal risk of ACHD
Prior cardiac event (TIA, stroke, arrhythmia, heart failure)
NYHA > grade II pre-pregnancy
L heart obstruction – mitral or aortic stenosis, CoA
LV EF <40%
Risk scores for pregnancy
WHO
ROPAC
CARPREG 2
CHD related to Down syndrome
ASD
VSD - main one
AVSD
ToF
CHD related to Turner syndrome
BAV
CoA
VSD
ASD
CHD related to Marfans’
Dilated Ao
Aortopathy
Psychological issues in ACHD
Ill health and poor schooling – employment difficulties
Difficulty w/ insurance
Self-image – scar on chest
Lifelong follow-up, tests, spectre of intervention
QoL
Why is MAP closer to diastolic pressure than systolic pressure
Diastole lasts 2x as long as systole
Short term control of MAP - mechanism
Neural
Long term control of MAP - mechanisms
Hormonal
What is MAP determined by
Blood volume
CO
TPR
Distribution of blood between arterial and venous blood vessels
Stimulus for ANP
Increased blood volume causes increased atrial stretch
Systemic response to ANP
Increased GFR
Decreased Renin
Inhibits aldosterone
Decreases BP
What is HTN
A rise in arterial bp sufficient to raise the incidence of strokes, MI. HF and renal failure
What is HTN
A rise in arterial bp sufficient to raise the incidence of strokes, MI. HF and renal failure
What is HTN
A rise in arterial bp sufficient to raise the incidence of strokes, MI. HF and renal failure
1’ HTN and 2’ HTN
1’ HTN is essential - no obvious predisposing organic cause
2’ - identifiable pathological cause
Proposed model for genesis of HTN
HTN initially due to increases in HR but normal TPR
Over time CO falls, with TPR increases permenantly
Haemodynamic types of HTN
Systolic HTN in the young (increased CO)
Diastolic/ combined hTN of middle age (increased TPR +/- CO)
Isolated systolic HTN in older adults (increased TPR & arterial stiffness)
Haemodynamic types of HTN
Systolic HTN in the young (increased CO)
Diastolic/ combined HTN of middle age (increased TPR +/- CO)
Isolated systolic HTN in older adults (increased TPR & arterial stiffness)
Mechanisms of primary HTN
Genetic
Kidney and Na handling
Neurogenic & humoral theories
Vascular remodelling
Condns causing 2’ HTN
Pre-eclamptic toxaemia
2’ Hyperaldosteronism (Conn’s syndrome)
Renal artery stenosis
Phaechromocytoma
Pe-eclamptic toxaemia causing HTN
Spiral arteries don’t dilate normally, causing placental ischaemia
Toxins released lead to reduction in endothelial NO/ prostacyclin production
Raised endothelin production
Peripheral vasoconstriction and HTN
Threshold for pre-eclamptic toxaemia
≥140/90 mmHg during pregnancy, w/ proteinuria >0.3g/day
Conn’s syndrome causing HTN
Adrenal tumour leads to excess aldosterone production
Stimulates Na and water retention by kidney
Renal artery stenosis causing HTN
Activates RAAS
Phaechromocytoma causing HTN
Adrenal medulla, catecholamine secreting tumour
α-adrenoreceptor activation (vasoconstriction) leads to hypertension
Main types of lipid in our bodies
Triglycerides
Phospholipid
Steroid
What di we need cholesterol for
Used to make steroid hormones and bile salts
Increases cell membrane fluidity
Cholesterol structure
Hydrohilic heads
4 fused hydrocarbon rings
Hydrophobic tails
Why do gats need to eb transported correctly
Or else they ppt in blood vessels, forming plaques
By how much is cholesterol solubility increased in our bodies
600x
Major source of cholesterol in the body
Diet - eggs, fatty foods, kidney, liver, prawns
Cholesterol transport cycle
Liver makes bile salts which act as detergents to assist in absorption of insoluble cholesterol from intestine
Cholesterol (complexed w/ bile salts) is taken into intestinal epithelium and packaged into lipoprotein particles
Cholesterol is transferred between lipoproteins for delivery from intestine to cells and back to liver
What is LDL a measure of
Cholesterol headed to tissue - ‘bad cholesterol’
Target range of lDL cholesterol
70-130 mg/dL (lower is better)
What is HDL a measure of
Cholesterol headed to liver for excretion via bile salts
Target range of HDL
40-60 mg/dL (higher is better)
Target range for total cholesterol in blood
<200mg/ dL
Where do you see xanthomas in people with familial hypercholesterolaemia
Around eyelids
Tendons of hands, elbows, knees, and feet
How do statins lower blood cholesterol
Main mechanisms is increased expression of lDL receptor
Inhibit HMG CoA reductase
Indirectly promote cholesterol uptake into cells via LDLR through -ve feedback
Inhibits cholesterol synthesis inside cells
When can statins be ineffective
If dietary intake of cholesterols excessive
What are we trying to prevent when aiming to lower BP
CVA CHD HF Renal dysfunction Aortic dilatation and dissection Occular complivcatsions Vascular dementia
Epidemiology of HTN
V common in UK pop
Prevalence influenced by age and lifestyle factors
23% of adult UK pop have hTN, 50% of those 60+ have HTN
What may result from untreated HTN
CVD and renal damage leading to a treatment resistant state
What is each 2mmHg rise in systolic bp associated w/
Proportional increased risk of mortality
7% from heart disease
10% from stroke
What is stroke prevention in HTN most dependent on
The treatments used
The amount of blood pressure lowering
The type of pts treated
Duration of therapy
Key priorities for implementing HTN mx
Dx
Risk assessment
Initiating and monitoring antihypertensive drug treatment
Choosing antihypertensive drug treatment
Pt knowledge, education and motivation
Treatments are usually life-long
Dx of HTN
If clinical BP is 140/90 mmHg or higher, offer ABPM to confirm dx - at least 2 measurement/ hr (14 minimum for day)
Take 2nd reading in clinic, if substantial different from the first, take 3rd
While waiting for confirmation of dx, carry out ix for target organ damage
Examples of target organ in HTN
LVH
CKD
Hypertensive retinopathy
Risk assessment for HTN
Carried out to guide treatment of spp risk factors
Clinical risk scores
Framingham risk score
QRISK 2/3 - most reliable
Associated condns of HTN
CDV disease (coronary, peripheral, cerebral)
Renal impairment
DM
Organs that may be damaged from HTN
Eye Brain Kidney Heart Other
Retinal changes in HTN
Hard exudates
Cotton wool spots
Flame haemorrhage
Arterio-venous nipping
Criteria for LVH on ECG
S wave depth in V1 + tallest R wave height in V5/6 > 35 mm
LAD
Lateral ST segment depression w/ T wave flattening/ inversion
Stage 1 HTN
Clinic BP is 140/90 mmHg or other ABPM/ HBPM is 135/85 mmHg or higher
Stage 2 HTN
Clinic BP is 160/100 mmHG or higher and ABPM/HBPM is 150/95 mmHg or higher
Stage 3 HTN (severe HTN)
Clinic BP is 180 mmHg or higher or clinic diastolic is 120 mmHG or higher
White-coat HTN
A discrepancy of more than 20/10 mmHg between clinic and avg daytime ABPM/ HBPM BP measurement at time of dx
Why do we assess hypertensive pts
To find out aetiology, target organ damage, risk factors etc
What does the assessment of the hypertensive pts require
Full hx - PMH, SH, risk factors Careful examination - CDV, peripheral pulses, retinal exam Formal risk assessment Key basic tests Spp tests
Key basic tests for HTN pts
ECG Renal function (incl eGFR) Na K Cholesterol Glucose/ HbA1c FBC Urinalysis for protein ABPM/ HBPM Fundoscopy - looking for hypertensive retinopathy
ABPM
Ambulatory BP monitoring
HBPM
Home BP monitoring
Spp tets for hypertensive pts
CXR Echo Renal ultrasounds Tests for 2' HTN Albumin/ creatine ratio
General measures for BP lowering
Wt Dietary salt Alcohol Exercise Smoking
Wt as mx of BP
Every Kg reduction is associated w/ 1-2mmHg drop in systolic BP
Dietary salt and mx of BP
Suggested to reduce daily intake to 6g
Alcohol and mx of BP
Association between increased alcohol and elevated BP
Exercise and mx of BP
Heavy physical exercise associated w/ reduced BP
Smoking and mx of BP
No clear association
General adverse risk factor
Summary of antihypertensives
Aged <55 yrs or DM - ACEi/ ARB
Aged >55 or Afro/Carribbean - CCB
Step 2 is ACEi/ARB and CCB Step 3 is add this=azide-like diuretic e.g. indapamide, bendrofluazide Step 4 (resistant HTN) - consider further diuretic e.g. Spiro or BB
Who do we offer antihypertensive drug treatment to
Anyone w/ stage 2 HTN
Those w/ stage 1 HTN, <80 who meet identified criteria (DM, CDV, renal disease, target organ damage, 10-yr CDV risk > 10%)
What should you do if someone has stage 1 HTN but doesn’t meet all the criteria for antihypertensives
Do further assessment
Monitoring drug treatment for HTN
Using clinic BP measurements, aim for 140/90 mmHg in those <80 and 150/90 in 80+
Aim for ABPM/ HBPM target bag of <135/85 mmHg in people aged under 80 and <145/85 mmHg in people 80+
Long term mx of HTN
Partnership care - pt has greater role
Mx of other health condns (CVD, renal, DM, prior CVA)
Mx of other risk factors e.g. cholesterol, smoking, wt
Appropriate diet and lifestyle measures
HBPM
Med review, compliance and appropriate dosing
Encouragement, support and counselling
Monitoring for those on step 4 HTN treatments
Serum Na, K and renal function
Why should pregnant women be offered alternatives to ACEi and ARBs when pregnant
These can cause congenital abnormalities
Alternatives incl methyldopa, labetolol and slow-release nifedipine
Using HBPM to confirm dx of HTN
For each recording, take 2 consecutive measurements at least 1 min apart w/ pt seated
Record bP 2x/day - morning and night for 4/7 (ideally 7/7)
Discard measurements taken on 1st data and use avg value of all other measurements
What 3 ducts are present at birth
Ductus venous
Ductus arteriosus
Foramen ovale
How does the ductus venous close after birth
Physiological sphincter
How does the ductus arteriosus close after birth
Pulmonary Vascular resistance decreases as SVR increases
How does the foramen ovale close after birth
Pressure in LA rises
Examples of acyanotic CHD
VSD PDA ASD Pulmonary stenosis AS CoA
Examples of cyanotic CHD
ToF
Transposition of great arteries (TGA)
CHD resulting in L to R shunt
VSD
PDA
ASD
All acyanotic
CHD resulting in outflow obstruction
Pulmonary stenosis
AS
CoA
Murmur heard in VSD
Pansystolic
Murmur heard in PDA
Continuous, machinery-like
Murmur heard in ASD
Ejection systolic
Murmur heard in ToF
Cresecendo-decresdo systolic
What feature is more likely to cause cyanosis
Cyanosis is more likely to occur when blood cannot get to lungs vs when cannot circulate around body
More likely in R —> L shunt
What is Eisenmenger’s syndrome caused by
Complication of untreated L —> R shunt due to pulmonary HTN
Features of innocent murmurs
Soft Systolic Short LSE Asymptomatic
Mx of PDA
Indamethicin/ ibuprofen
Catheter closure
Medical mx of CoA
IV infusion of PGE1 - keeps duct open
Dobutamine/ dopamine - improve contractility
Supportive care to correct any consequences of HF
Therapeutics for ToF
Oxygen
Morphine
BB
Dig & furosemide - HF
ECG findings in hypothermia
J wave
+ve deflection seen between QRS complex and ST segment
When do we see U waves
Hypokalemia
Bradycardia
Causes of J wave
Hypothermia
Hypercalcaemia
SAH
