Week 8 Heart Murmur Flashcards
What are the two main branches of the right coronary artery ?
Acute marginal
Posterior descending artery (PDA)
What does the left main coronary artery divide into ?
Left anterior descending artery
Left circumflex artery
How is the period of systole defined ?
Time between atrioventricular valve closure and semilunar valve closer
When is aortic pressure at its lowest ?
Late diastole
What happens to the mitral valve when LV pressure becomes greater than LA pressure ?
Mitral valve closes
What is the isovolumetric contraction time ?
Period of time during which the LV pressure increases but the LV volume remains constant.
Why does the LA pressure increasing transiently during IVCT
The mitral valve bulges into the LA
When does the aortic valve open ?
When the LV pressure > aortic pressure
When does the aortic valve close ?
When the LV pressure dips below that of the intrinsic aortic pressure
What is the incisura or dicrotic notch ?
The transient increase in aortic pressure caused by the abrupt closure of the aortic valve
What is the isovolumetric relaxation time ?
Period of time during which the LV pressure is decreasing but the LV volume remains constant
When does the mitral valve open ?
When the LV pressure dips below that of the LA
What causes S1 ?
Closure of the atrioventricular valves (mitral and tricuspid)
What causes S2?
Closure of the semilunar valves (aortic and pulmonary)
What is the time between S1 and S2 defined as ?
Systole
What is the time interval between S2 and S1 defined as?
Diastole
What causes S3 ?
Rapid cessation of blood flow in early diastole in the presence of volume overload
When does S3 occur ?
Early diastole
When does S4 occur ?
Late diastole
What causes S4 ?
Occurs in presence of a pressure overload ventricle: extra pressure and volume conferred by atrial constriction into stiff ventricle —> abnormal heart sound
What causes an ejection click ?
Abnormal opening of a semilunar valve
What causes an opening snap ?
Rheumatic mitral valve stenosis
What are the two components of S1 ?
M1 and T1
What are the 2 components of the second heart sound ?
A2 and P2
What two heart sounds can be identified separately on auscultation ?
A2 and P2: splitting of the second heart sound
Heart sounds from which side of the heart are heard first ?
Left
What happens to the Intra thoracic pressure on inspiration ?
Becomes negative
What happens when there is negative intrathoracic pressure ?
Pulmonary vascular resistance decreases
Volume of blood returning to right heart increases
More blood stays in pulmonary vasculature
What happens to the left side of the heart when there is increased right heart blood volume return ?
Left side pressure decreases as a result of decreased left side blood return (increased blood stays in pulmonary vasculature)
Why do the left sided heart valves close earlier during inspiration ?
Left sided pressures and blood volumes decrease
What happens to S2 split on inspiration ?
Increases
What 3 things cause a heart murmur ?
Increased flow through normal structures
Increased turbulent flow through abnormal and small orifices
Increased flow from a narrow proximal chamber to a dilated distal chamber
Which one causes a systolic murmur ?
A. Severe anemia
B. Aortic stenosis
C. VSD
All of the above
When does stenosis occur ?
When a valve cannot fully open
When does regurgitation occur?
When a valve cannot fully close
How do electrical signals travel through the heart ?
Sinus node —> AV node —> Bundle of His
When does the P wave occur ?
Late diastole
When does the QRS complex occur ?
End of diastole (electrical signal for ventricular contraction)
What wave is associated with LV relaxation ?
T wave (late systole)
What is the ejection fraction ?
Stroke volume/ left ventricular end-diastolic volume
55-65% is normal
What are the 3 determinants of stroke volume ?
Preload ~ LVEDV
After load
Contractility
What is afterload ?
Ventricular wall stress encountered during contraction that must be overcome in order to eject blood
Law of Laplace
Wall stress = (P x r)/(2h)
What is the effect of afterload on stroke volume ?
Increased afterload —> decreased stroke volume
Affect of contractility on stroke volume
Increased contractility —> increased stroke volume (to a point)
How much can cardiac output increase during exercise ?
5-7 times the normal amount
What is concentric hypertrophy ?
An increase in myocardial wall thickness secondary to chronic pressure overload
What is eccentric hypertrophy ?
An increase in cardiac chamber radius secondary to chronic volume overload
What can concentric hypertrophy result in ?
Increase in myocardial oxygen consumption Increase in myocardial workload Decreased ventricular compliance Decrease in chamber cavity size Negative geometric remodelling Decreased stroke volume Impaired systolic function
Definition of congenital heart disease ?
Abnormal formation or function of the heart, present at or before birth
What are some possible environmental causes of CHDs ?
Alcohol exposures
Infections
Medications
Maternal conditions
What are some possible genetic causes of CHDs ?
Abnormal number of chromosomes (trisomy 21, Turner syndrome)
Microdeletions (22q.11)
Single gene syndromes
What is the most common congenital malformation ?
CHD
What is situs solitus, inversus, and isomerism ?
Normal position in the body
Reversed position in the body
Mixed up position in the body
When does pump malfunction occur ?
If muscle is defective
If there is inadequate filling
If there is too much fluid in the pump
If there is too much resistance to output
In prenatal diagnosis of CHDs what symptom complexes can be recognized ?
Heart rate and rhythm abnormality
Hydrops fetalis: edema of the whole body
Structural abnormality of the heart
What does congenital heart block cause ?
Decrease heart rate
What can valve insufficiency and myocardial dysfunction lead to ?
Edema of the whole body (hydrops fetalis)
When in pregnancy is an anomaly screen conducted in BC ?
18-20 weeks
Describe fetal circulation
Single circulation with oxygenator in the circuit
Describe transitional circulation
Equal R and L ventricular pressures
Circulatory bypass via PFO and PDA
Describe neonatal circulation
Two circulations in series
Pulmonary resistance starts to fall
Cardiac outputs must be balanced
What is the incidence of critical heart disease in neonates ?
3:1000
Describe the cyanotic symptom complex
Presence of reduced hemoglobin in the systemic circulation
Oxygen saturation of <95%
What can cause cyanosis ?
Intra-cardiac shunt
Transposition physiology
Signs of tetralogy of fallot
Reduced O2 sat (<80%)
Ejection systolic murmur
Describe the effect of transposition
2 circulations in parallel
Saturation 60%
Describe tricuspid atresia and its effects
Single ventricle —> mixing of venous return at atrial and ventricular level
Variable restriction to pulmonary blood flow
Cyanosis
Presentation of afterload problem in the newborn
Poor pulses
Respiratory distress and shock
Conditions that cause afterload problems
Aortic stenosis
Coarctation
Interrupted arch
Hypoplastic left heart syndrome
Presentation of preload problem in infants
Tachypnea
Poor feeding
Failure to thrive
Conditions that can cause preload problems in infants
Regurgitant valves
L-R shunt at VSD
L-R shunt at ductus
Presentation of complete mixing disorders in infants
High pulmonary blood flow
Minimal cyanosis
Conditions that can cause complete mixing in infants
Atrial- TAPVR (total anomalous pulmonary Venus return)
Single ventricle with no outlet obstruction
Arterial: truncus arteriosus
Recognition of CHF in children
Heart failure symptoms Asymptomatic murmur Most common: Ejection murmur off AS or PS Regurgitant murmur of VSD Uncommon: Muscle dysfunction Coarctation
Criteria for characterizing heart murmurs
Location Radiation Cardiac cycle Duration Intensity
Patent foramen ovale remains open in what percentage of adults
~30%
How common is VSD In live birth CHDs
32% of patients
Important examinations for recognizing CHDs
Growth charts RR Work of breathing Mucous membranes O2 sat BP, HR Precordial impulse Heart sounds Perfusion, pulses Liver, lungs
Common tests for CHDs
ECG
Echocardiogram
Others: Exercise testing CXR Cardiac catheterization CT MRI
What can cardiac catheterization measure ?
Intra-cardiac pressures and blood flow
Angiography to define structural abnormalities
Which layer of the mesoderm forms the cardiac precursor cells
Splanchnic
What do cardiac precursor cells form ?
1st and 2nd heart fields
Where do the cardiac precursor cells arise from?
Splanchnic mesoderm if the head (cranial) end
Describe the arrangement of the 1st heart field
Arranged in a crescent shape: cardiac crescent
Describe the 2nd heart field
Cardiac cells that arise in the same region as the 1st heart field at a slightly later time, and form endocardial tubes
When do the endocardial tubes form ?
Day 19
When do heart tubes fuse together ? And what do they form ?
Day 21
Endothelium
What is the result of incomplete lateral folding ?
Anterior body wall defects
How does cephalocaudal folding move the Heart ?
Brings heart from the head to the thorax
What does lateral folding do ?
Brings the two heart tubes together to fold in the midline to make a single tube
When do cephalocaudal and lateral folding happen in relation to each other ?
Simultaneously
What is the first organ to function ?
Heart
When does the heart start to beat and when does it start to fold ?
Day 22 and day 23
What does the myocardium form from ?
2nd heart field
What is the outflow end of the heart fixed into ?
Aortic arches
What is the inflow end of the of the heart fixed to ?
Veins that are coming into the heart
Why does cardiac looping occur ?
The Heart is. Fixed on the inflow and outflow end so when it lengthens it is forced to bend (loop)
What does the bulbus cordis develop into ?
Outflow channels (aorta and pulmonary trunk)
What does the primitive ventricle develop into ?
R & L ventricles
What does the primitive atria develop into ?
R & L auricles
What does part of the right atrium and SVC develop into ?
Coronary sinus
Where does the bulbus cordis move during cardiac looping ?
Inferiorly and right
Where does the primitive ventricle move during cardiac looping ?
Left
Where does the primitive atrium move during cardiac looping ?
Superiorly and posteriorly
Where does the sinus venosus move during cardiac looping ?
Posterior and superiorly
What will happen if normal folding of the heart doesn’t occur?
Development of the heart will not continue
When does cardiac looping occur ?
Day 23-28 (week 4)
What are some consequences of abnormal cardiac rotation ?
Dextrocardia and situs inversus
The growth of what is responsible for atrioventricular partitioning
Posterior and anterior endocardial cushions
Aorticopulmonary septum contributes to the formation of what ?
Membranous interventricular septum
When does the atrioventricular septum form ?
Day 228 - day 42
When does the foramen ovale form ?
Day 28 - day 46
What two septums form to leave the foramen ovale ?
Septum primum and septum secundum
What is the septum primum ?
A muscular septum which forms from the dorsal part of the roof of the primitive atrium
Grows downward toward fusing endocardial cushions
Flexible
What is the septum secundum ?
Grows from the ventral part of the roof of the primitive atrium
Grows towards the endocardial cushions
Sturdy
When does the interventricular septum form ?
Day 28-46
How does the interventricular septum grow?
Grows upward from the midline floor of the primitive ventricle
When does the aorticopulmonary septum form ?
Day 35-56
How does the separation of the bulbus cordis and truncus arteriosus start ?
3 ridges that appear at the sides of the bulbus and truncus
What happens with the right and left conotruncal ridges during heart development ?
Widen and fuse together in a spiral separation between pulmonary trunk and aorta
When does the interventricular septum form (membranous portion)?
Day 42-56
What is the membraneous portion of the inter-ventricular septum an extension of ?
Aorticopulmonary septum
What are the 4 steps involved in the sequential segmental analysis approach ?
- Determine cardiac sidedness and cardiac position
- Morphological identification of the cardiac chamber and great arteries
- Analyze the connections and relations
- Assess the associated anomalies of each segment
What happens with blood when there is an ASD present in the heart ?
Mixing of systemic and pulmonary blood
Left - Right shunt
—> dilated right atrium, ventricle and pulmonary artery
What interventions are available for an ASD ?
Surgical closure using a patch
Interventional catheterization
Characterization of Tetralogy of Fallot
Cyanotic
- VSD
- over riding aorta
- pulmonary stenosis
- right ventricular hypertrophy
Key feature: anterior deviation of the infundibular septum
Shunt can be either direction depending on relative pressure
When is intervention generally taken with tetralogy of fallot ?
Neonatal - 6 months
Determined by severity of outflow tract obstruction
What is the most common cyanotic heart defect presenting in neonates ?
Transposition of Great arteries
What happens to the circulation connection with TGA ?
Connected in parallel rather than in series
Aorta connected to right ventricle
Pulmonary artery connected to left ventricle
—> oxygenated blood flows to lungs
What is critical for survival in patients with TGA ?
Mixing of blood (ASD, VSD, PDA)
What surgical repair is done for patients with TGA ?
Arterial switch operation
What is coarctation of the aorta ?
Narrowing of the aorta
How does BP present in patients with coarctation of the aorta ?
Reduced BP in femoral pulse (legs)
Elevated BP in arms
What can be prescribed to keep a PDA open temporarily ?
Prostaglandin E1
How can coarctation of the aorta be repaired ?
Cardiac catheterization:
Stent inflated by balloon placed over area of narrow
Surgical:
Cut area of narrowing and anastomose the 2 ends together
What is truncus arteriousus ?
Lesion characterized by single arterial vessel that gives rise to the systemic, pulmonary and coronary circulations.
Single semilunar valve present
Repair of truncus arteriosus
VSD closed with patch: truncal valve arises from left ventricle —> new aortic valve
Valved conduit is used to create a path from the right ventricle to the pulmonary arteries
What is hypoplastic left heart syndrome ?
Critically underdeveloped left side of the heart:
Single ventricle anatomy
PFO —> left to right obligate shunting
Some blood will shunt through PDA to supply aorta
Management of hypoplastic left heart syndrome
Prostaglandin E1 to keep PDA open temporarily Then 3 major surgeries: Norwood procedure Bidirectional Glenn connection Fontan surgery
What is the Norwood procedure and when is it performed ?
Performed in 1st week of life in patients with hypoplastic left heart syndrome
Create new aorta from pulmonary artery and create anastomosis to the native aorta as the coronary arteries arise from this vessel, placing a shunt to supply lungs its limited amount of flow opening up the ASD so it is unrestrictive
What is the bidirectional Glenn connection surgery and when is it performed ?
Performed at about 6 months in patients with HLHS
Disconnect SVC from heart and connect it directly to the pulmonary artery
What is the Fontan surgery and when is it performed ?
Performed at 3-4 years in patients with HLHS
Disconnect the IVC from the heart and connect it directly to pulmonary artery
What is the prevalence of CHD ?
8-11 per 1000 live births
What is the leading cause of neonatal mortality ?
CHD
What is the benefit of reducing a patients body temperature before heart surgery ?
Reduce the amount of oxygen needed —> safer
When in fetal development does cardiac development occur ?
Weeks 4-7
Describe fetal circulation
Oxygenated blood placenta —> UV through liver —> IVC —> RA —> PFO —> LA —> LV —> aorta —> brain and coronaries
SVC blood —> RA —> RV —> PA —> PDA —> descending aorta
Describe postnatal circulation
Placenta eliminated —> increase SVR
Lung expansion —> decreased PVR
Increased PO2 —> further decrease in PVR —> increase in pulmonary blood flow —> increase LA pressure —> closure of PFO
Increased PO2 —> closure PDA
What is CHD ?
Failure of myocardial oxygen supply to meet myocardial oxygen demand
How does CHD present in infants ?
Tachypnea
Tachycardia
Diaphoresis
Hepatomegaly
Why does CHD result in volume overload ?
Large communication between systemic and pulmonary circulations
Valvular regurgitant lesions
Why does CHD lead to pressure overload ?
Obstruction to ventricular emptying
What does a PDA connect ?
Aorta and pulmonary artery
Are ASDs more common in females or males?
Female (~2-3x)
What is the most common congenital cardiac anomaly
VSD
How does coarctation of the aorta present in infancy vs older children ?
CHF
Hypertension
Examples of cyanotic CHDs
TGA Tetralogy of fallot Total anomalous pulmonary venous return Truncus arteriosus Single ventricle (HLHS)
What is total anomalous pulmonary venous drainage ?
Anomalous drainage of the entire pulmonary venous circulation directly into the RA or via systemic veins connecting with the RA
Compensatory right to left shunt through PFO for survival
Surgical emergency
How does high output failure present ?
Poor growth
How does low output failure present ?
Poor perfusion
What are the two most important objectives in the management of an infant/child with shunt physiology ?
Optimize growth and nutrition
Ensure developmental milestones
How to optimize growth and nutrition in infants with fast breathing
Diuretics
Digoxin
How to optimize growth and nutrition in infants with slow weight gain ?
Additional calories: 24 or 27 Kcal supplements
NG feeds
How to optimize growth and nutrition in infants with mechanical heart problem ?
Surgery
What 3 tests are used to determine why an infant is cyanotic ?
Hyperoxic test
CXR
Electrocardiogram
Pulmonary problem will improve with O2 therapy cardiac problem wont
What shape is the heart with tetralogy of fallot ?
Boot shaped
What can a fetal echocardiograph assess
Structure
Function
Heart rate and rhythm
Intra cardiac shunts
Atrial septal defect
Ventricular septal defect
Atrio-ventricular septal defect
Extra-cardiac shunts
PDA
Aorta pulmonary window
Left to right shunts
ASD
VSD
AVSD
PDA
Right to left shunts
Eisenmenger syndrome (VSD, AVSD, PDA) Tetralogy of fallot
Mixed cyanotic shunt
TGA
What does the degree and direction of shunting depend on ?
Pressure difference between chambers
Relative compliance between chambers
Size of defect
Sequela of VSD left to right shunt
Pulmonary over circulation Pulmonary hypertension Left sided chamber dilation Left sided chamber dysfunction Clinical heart failure Arrhythmias
What changes do you expect to see with O2 sat in VSD left to right shunt ?
Increased RV and PA O2 sat
Changes in O2 sat with PDA left to right shunt
Increased PA O2 sat
Outline the progression to Eisenmenger syndrome
Left to right shunting —> pulmonary over circulation —> pulmonary hypertension —> severe pulmonary hypertension —> pulmonary pressures exceed systemic pressures —> right to left shunting
Why does right to left shunting occur with tetralogy of fallot ?
Severe right ventricular outflow tract obstruction
Changes in O2 sat with right to left shunt in tetralogy of fallot
Decreased RV, LV and aortic O2 sat
Changes in O2 sat in TGA
Increased PA O2 sat
Decreased aortic O2 sat
Sequela of aortic coarctation
Hypertension Increased LV pressure Distal hypoperfusion Progressive LV dilation and dysfunction Clinical heart failure
Long term progression of ASD
Progressive functional impairment through 3-5 decades
- arrhythmia
- RV dysfunction
- paradoxical embolic phenomena
- pulmonary vascular disease
When is the ideal time to intervene with ASD ?
First decade
Effects of moderate to large VSD
Volume loads -LA, LV -pulmonary vasculature Pressure loads -RV/PA depending on size/shunt May become smaller or spontaneously close
Effects of large VSD
Pressure and volume loads CHF, FTT Infection Pulmonary vascular disease Eisenmenger syndrome
When is the decision to repair a VSD usually made by ?
4-6 months
What is pulmonary hypertension ?
Elevated pulmonary artery pressure
Which CHDs tend to result on pulmonary vascular disease (pulmonary hypertension) ?
VSD, PDA, TGA sometimes ASD
What is the difference between stenosis and coarctation ?
Both are partial obstruction to flow but stenosis is in valves coarctation is in vessels
What do obstructive lesions lead to ?
Chronic increased afterload
What does coarctation of the aorta lead to pressure load on ?
Ascending aorta
Aortic valve
LV
LA
Possible consequences of coarctation of the aorta
Chronic hypertension LV hypertrophy Cerebrovascular event Dissection of the aorta Infective endocarditis Angina = LV failure Morbidity from early teens Associated aortic stenosis
Interventions for coarctation
Surgery
Angioplasty
Bicuspid aortic valve, aortopathy
Coarctation outcomes with older age at repair
Hypertension
Coronary artery disease
Vascular anomalies
What is a major issue with atrial repair in transposition ?
RV failure (CHF)
Effects of unoperated tetralogy of fallot
95% mortality by young adult years Progressive cyanosis Progressive right to left shunt Erythrocytosis Stroke, cerebral abscess, gout
Long term effects of tetralogy of fallot
Pulmonary valve regurgitation
Atrial arrhythmia
LV function
Ventricular arrhythmia and SCD
Risk of pregnancy with ASD, VSD, PDA
Low risk-less 1%
Risk of pregnancy with aortic stenosis, coarctation, unoperated tetralogy, severe pulmonic stenosis
Medium risk 5-15%
Risk of pregnancy in patients with complex coarctation and pulmonary hypertension ?
High risk 25-50 %