PEDIATRIC CARDIOLOGY

2.3A
10/17/16
Ruby Ann Punongbayan, MD

OUTLINE o 2 types:
I. History Taking § Central (under tongue, lips, perioral)
A. Gestational History
B. Postnatal History
C. Family History
II. Physical Examination
A. Inspection
B. Palpation
C. Auscultation
III. Diagnostic Work-up
A. Echocardiography
B. Chest Radiography
Cyanosis of tongue and circumoral cyanosis
C. Others
IV. Normal Heart Development & Physiology
§ Peripheral (nail beds)
A. Cardiac Morphogenesis
B. Fetal Circulation
C. Transitional Circulation
D. Neonatal Circulation
V. Normal Blood Circulation

HISTORY TAKING
GESTATIONAL HISTORY
• Infections, medications, smoking and alcohol intake during
pregnancy
• Birth weight
o An average Filipino baby usually weighs 3 kg or 6 ½ pounds Cyanosis of the nail beds
at birth
• ACROCYANOSIS
POSTNATAL HISTORY o Cyanosis of ONLY the EXTREMITIES of newborns
• Weight gain, development, feeding patterns o As a response to cold sensation
o Weight loss commonly seen o Must be differentiated from TRUE CYANOSIS wherein
o
o Failure to thrive MAY BE 2 to CARDIAC FAILURE there is ALSO blue coloration of mucous membranes
o A normal infant will feed continuously
§ Hindi daw dapat humihinto hanggang hindi umaabot dun CLUBBING
sa point na busog na ‘yung baby • INDICATION:
o Altered feeding patterns - very important manifestation of o >6 months of ARTERIAL DESATURATION (≤80%)
CONGENITAL HEART PROBLEM o Can possibly be familial
§ Interrupted feeding - notable observation in CHD § Check if any immediate family relatives have the same
§ Easy fatigability - ito ‘yun demonstration ni Dra na “inom- condition
inom-inom-stop… inom-inom-inom-stop… § Space between apposed thumbs is checked whether
• Cyanosis, squatting there is space obliteration or a diamond-shaped space
• Tachypnea, dyspnea, puffy eyelids - Normal: Diamond-shaped space
• Frequency of respiratory infections - Schamroth’s sign: The space is obliterated
o Most usually manifested in acyanotic patient
o Recurrent pneumonia
• Exercise intolerance
• Not obvious in babies
• Murmur
• Chest pain
• Joint symptoms
• Neurologic symptoms
• Medications
Schamroth’s sign
FAMILY HISTORY
• Hereditary disease
• Clubbing is not commonly manifested in children even in severe
• Congenital heart disease arterial desaturation UNLESS the baby is in his/her LATE 1
st
o Multifactorial in inheritance year of life
o Combination of genetic and environmental factors
• Rheumatic fever RESPIRATORY SIGNS
• Sudden unexpected death • Rate of breathing of the baby must be always checked
• DM, atherosclerotic heart disease, hypertension • See if there are retractions on chest wall
• Observe for use of accessory muscles
PHYSICAL EXAMINATION • See if difficulty of breathing/dyspnea is present
INSPECTION
• Consider general appearance and nutritional state of the patient SWEAT ON FOREHEAD
• Chromosomal syndromes • Presence is a sign of INCREASED SYMPATHETIC ACTIVITY
o Trisomy 21 o Compensatory mechanism for DECREASED CO
§ 20% with ATRIOVENTRICULAR SEPTUM
o Trisomy 18 CHEST INSPECTION
§ 80% with PULMONARY STENOSIS • Dynamic or adynamic precordium
• Pulsations may be observed and seen over various parts of
COLOR epigastrium and chest
• <85% arterial saturation
o Before CYANOSIS can be detected • PRECORDIAL BULGE
o Normal saturation is 95-100% o Can be best seen by having the patient lay supine with
• Cyanosis examiner looking up from child’s feet
o Observed on nail beds, lips, tongue, mucous membranes

HawHaw 1 of 7
PEDIA2: PEDIATRIC CARDIOLOGY 2.3

• Abnormal pulsations and movement

• More diffuse and slow rising
• indicates volume overload
Heave • An apical heave is noted with
LV enlargement
• Well localized and sharp
Tap rising
• Indicates pressure overload
• Volume overload (PDA,
Hyperactive VSD, AR, MR)
precordium • If you have a thin patient, this
Precordial bulge and Harrison’s groove may be NORMAL.
• Vibratory sensations that
• PECTUS CARINATUM represent palpable
manifestations of loud,
harsh murmurs
• Minimum grading that can
Thrills be assigned: 4
• Accdg to Dra, ito yung parang
may kumakamot or scratching
sensation when fingers are
placed over the precordium

• Overly silent precordium

o Barely detectable apical impulse
o Suggests pericardial effusion or severe cardiomyopathy
o May be normal in an obese patient
Pectus carinatum (pigeon’s chest) of a female patient Right lower sternal • Characteristic of VSD
border thrills
• PECTUS EXCAVATUM Apical systolic • Characteristic of mitral
thrills insufficiency
• Occasionally palpable in the
Diastolic thrills presence of atrioventricular
valve stenosis.

BLOOD PRESSURE MEASUREMENT

• Average of 3 blood pressure readings should be adopted in
pediatric patients
• Wide pulse pressure with bounding pulses may suggest:
o An aortic runoff lesion
§ PDA, AR, arterial-venous communication
o Increased cardiac output secondary to anemia or anxiety
o Conditions associated with increased catecholamine or
Pectus excavatum (Funnel chest)
thyroid hormone secretion
• HARRISON’S GROOVE
PERIPHERAL PULSES
o Line of depression at the bottom of the rib cage along
Full, equal • Normal
diaphragm attachment
§ Signifies poor lung compliance • This is usually found in patients with
o Due to longstanding dyspnea Bounding PATENT DUCTUS ARTERIOSUS (PDA)
o There is pulling of softened ribs by the diaphragm during the and AORTIC REGURGITATION
child’s inspiration • Cardiac failure
• Circulatory shock/ Hypovolemic shock
• COA:
o In older children with coarctation of the
aorta, blood flow to the descending
Weak or aorta may channel through collateral
thready vessels resulting in the femoral pulse
being palpable but delayed until after
the radial pulse (radial-femoral delay)
• Diminished pulses would be encountered
in cardiomyopathy and pericardial
tamponade

• PULSUS PARADOXUS (PP)

o Accdg to Nelson's:
Harrison’s groove due to rib softening while inspiration § A drop in systolic blood pressure during inspiration
>10mmHg
PALPATION § The normal fall in pressure is <10 mmHg in PP
CHEST PALPATION o In PP, cuff pressure is raised about 20 mmHg above the
• Apical impulse systolic pressure
o For the detection of cardiomegaly o On clinical examination, one can detect beats on cardiac
<7 yrs old • 4th ICS LMCL auscultation during inspiration that cannot be palpated at
>7 yrs old • 5th ICS LMCL the radial pulse
o Deviation LATERALLY AND INFERIORLY
§ Enlargement of the left ventricle AUSCULTATION
o RIGHT-SIDED APICAL IMPULSES HEART SOUND DESCRIPTION
§ Signify dextrocardia, tension pneumothorax, or left- • Closure of mitral and tricuspid valves
sided thoracic space-occupying lesions (e.g., • Best heard at the apex or lower left
st
diaphragmatic hernia) 1 heart sound sternal border
• Apex is either on 4th or 5th ICS MCL
• Point of maximal impulse (PMI) depending on child’s age
o Determines the dominant ventricle • Upper left sternal border
Right Ventricle • Xiphoid process • Closure of aortic and pulmonic valves
nd
Left Ventricle • Apex 2 heart sound • According to Nelson's, 2nd heart sound
should be evaluated at the upper left
and right sternal borders

HawHaw 2 of 7
PEDIA2: PEDIATRIC CARDIOLOGY 2.3

• Low-frequency sound in early diastole the receiving chamber and usually

related to rapid filling of the ventricle occur while the semilunar valves are
• Best heard at the apex (in mid diastole) still closed
• Commonly heard in normal children o Wavy quality
rd
3 heart sound • May be normal in an adolescent with o Associated only with VSD, MR, & TR
relatively slow heart rate o Abnormal valve (hindi nagdidikit ng
• Loud S3 is abnormal in conditions with maganda ang valves)
dilated ventricles and decreased • Occur between S2 and S1
compliance • Early, mid-diastolic, late diastolic
• Low-frequency sound of late diastole DIASTOLIC • Early diastolic murmurs due to
and rare in infants and children MURMUS incompetence of aortic or pulmonary
th
4 heart sound • When present, it is always pathologic valve
and seen in conditions with decreased • ALWAYS pathologic
ventricular compliance or CHF • Heard at the base
• Degree of splitting varies with • Begins in systole and continue without
respiration and increases with interruption through S2
Normal splitting inspiration & decreasing or becoming CONTINUOUS • Heard in PDA (classic example), COA,
of S2 single with expiration (Lub drab) MURMURS PA stenosis
• Drab – physiologic splitting of S2 • No distinction between the S1 and S2
• Appreciated in a very quiet room + • Continues or “spills” into diastole &
sensitive stethoscope indicates continuous flow
• Wide, narrow, single S2 or paradoxical • Arise from cardiovascular structures in
• Widely split and fixed S2 the absence of anatomic abnormalities
o Found in conditions that prolong the INNOCENT or • 80% of children about 3-4 yrs old
RV ejection time or that shorten the FUNCTIONAL • Accentuated or brought out in a high-
LV ejection (ASD, PS, MR, RBBB) MURMURS output state such in febrile illness (very
o Lub-darab” high fever)
Abnormal o e.g. ASD, PS, MR, RBBB • All diagnostic tests are normal
splitting of S2 • Narrowly split S2
o Pulmonary hypertension, AS MURMUR DESCRIPTION
o “Lub DUB” (malakas ang second • Detected between 3-6 yrs old
sound) • Mid-sternal border
• Single S2 • Mid-systolic in timing and grade 2-3/6
o Aortic or pulmonary atresia, PTA, Classic • “Twanging string” musical sound
TGA, TOF, severe PS vibratory • Heard best in supine position
• Rapid triple rhythm resulting from a murmur (SS – Still’s-Supine)
loud S3 with or without S4 and (Still’s murmur) • Not detected when sitting
tachycardia • Increased during febrile illness,
Gallop rhythm • Generally implies a pathologic
excitement, after exercise, anemic
condition and commonly present in states --> high cardiac output state
CHF • Common in 8-14 yrs old
• Attributed to poor compliance of the Pulmonary • Audible at upper left sternal border
ventricle ejection murmur • Early to midsystolic in timing and grade
of childhood 1-3/6
• Heart rate and regularity, heart sounds, systolic and diastolic
• Blowing in quality
sounds, heart murmurs
• Maximal at upper left sternal border
• The diaphragm of the stethoscope is placed firmly on the
chest for high-pitched sounds
• Usually disappears by 3-6 months of
Pulmonary flow age
• A lightly placed bell is optimal for low-pitched sounds murmur of • Transmits well to the left and right chest,
newborns axilla, and back
MURMURS
• Look for intensity, timing, location, transmission, quality
• Grade 1-2/6
• Auscultation for murmurs should be carried out across the • Common in 3-6 yrs old
upper precordium, down the left or right sternal border, and out • Maximal at right or left supraclavicular
to the apex and left axilla and infraclavicular areas
• Grade 1-3/6
GRADE DESCRIPTION • Heard only in upright position (unlike
Grade 1 Barely audible Still’s murmur)
Grade 2 Soft, but easily audible • Inaudible in the supine position
Grade 3 Moderately loud, but not accompanied by a thrill • Intensity changes with rotation of head
Grade 4 Louder and associated WITH A THRILL and compression of jugular vein
Grade 5 Audible with the stethoscope barely on the chest o Can be exaggerated or made to
Venous hum disappear by varying the position of
Grade 6 Audible with the stethoscope off the chest
the head
o Can be decreased by lightly
• In patients who has undergone prior heart surgery
compressing the jugular venous
o Murmur of grade IV or greater may be heard in the
system in the neck
absence of a thrill
o If di ka sigurado, ipaturn mo yung
head nung patient to one side,
• Ejection murmur maririnig mo na
o Heard best at S2 (at the base) • Produced by turbulence of blood in
o Interval between the S2 and onset of the jugular venous system
murmur
• Heard at any age
o Coincide with the ejection or flow of
blood through narrowed structures
• Right supraclavicular area and over
the carotids
(e.g. semilunar valves)
Carotid bruit • Grade 2- 3/6
o Caused by the flow of blood through
stenotic or deformed semilunar • Produced by turbulence in the
valves or by increased flow through brachiocephalic or carotid arteries
normal semilunar valves
o Audible at the 2nd LICS From 2015 Trans (Questions):
SYSTOLIC o Heard in PS and ASD Q1: When you appreciate a murmur, will it be routine to
MURMURS • Regurgitant murmurs request for ECG?
o Heard best at the apex *Doc: Yes. ECG is a very basic test to detect cardiac
o Heard at left lower sternal border problem. Then you decide if kailangan pa ng UTZ or 2D echo pag
o Begin with S1 meron abnormality in the ECG for confirmation.
o Caused by the flow of blood from a
chamber that is at a higher Q2: If the diagnostic tests are normal, will you still ask to
pressure throughout systole than patient to come back for follow up?

HawHaw 3 of 7
PEDIA2: PEDIATRIC CARDIOLOGY 2.3

*Doc: Definitely. You still have to monitor the patient. If identifies small or multiple left-
not able to appreciate murmur during follow up, then baka wala to-right or right-to-left shunts
talaga. • Done by a pediatric cardiologist
with the subspecialty of
DIAGNOSTIC WORK-UP interventional cardiology
ECHOCARDIOGRAPHY
• Best defines the morphologic features of intracardiac CHEST RADIOGRAPH
chambers, cardiac valves, and intracardiac shunts • Part of basic work-up of children with heart problem
• In congenital heart lesions: • Provide information about cardiac size, shape, pulmonary
o To evaluate cardiac structure blood flow (vascularity), pulmonary edema, and associated lung
• In stenotic valves and vessels: and thoracic anomalies that may be associated with congenital
o To estimate intracardiac pressures and gradients syndromes
• Quantitate cardiac contractile function • The most frequently used measurement of cardiac size is
• Determine the flow across a defect the maximal width of the cardiac shadow in a PA chest film
• In coronary arteries: taken mid-inspiration
o To examine the integrity • Enlargement of cardiac chambers or major arteries and veins
• In endocarditis, pericardial fluid, cardiac tumors, and results in the prominence of the areas in which these structures
thrombi: are normally outlined on the chest x-ray
o To detect the presence of vegetations • Always request for 2 views
• Used to assist in the performance of: o PA and Lateral
o Pericariocentesis o AP is taken in <2 y/o
o Balloon atrial septostomy § If more cooperative = can do PA
o Endocardial biopsy • Identify if midline structures are intact
• Basic Principle:
TYPES DESCRIPTION o Black = air; radiolucent
o White = solid; radio-opaque
• You can only appreciate RV in lateral view
o Normal:
§ With space between sternum and RV
o RV enlargement
§ RV fullness or retrosternal fullness
§ RV and sternum is very close
TRANSESOPHAGEAL • Extremely sensitive imaging • LV enlargement
ECHOCARDIOGRAPHY technique o Retrocardiac fullness
• Visualizes posteriorly located o Space behind heart is occupied by LV
structures • The term enlargement
• Extremely useful as o Describes big chambers of heart on X-ray
intraoperative technique for • The term hypertrophy
monitoring cardiac function o Used in describing big chambers on ECG
during both cardiac and non-
cardiac surgery
• For screening residual cardiac
defects after CP bypass
• Evaluates the degree of residual
regurgitation after repair of AV
septal defects
• 1-dimensional slice of cardiac
structure varying over time
• Mostly for the measurement of
cardiac dimensions (wall
thickness and chamber size) and
M-MODE cardiac function (fractional
shortening, wall thickening)
• Assess the motion of
intracardiac structures and
anatomy of valves
• Rarely used
• The contracting heart is imaged
in real-time using several
standard views that emphasize
Posteroanterior View
specific structures
• Better than angiography in
imaging the AV valves & their
chordal attachments
• Cardiac catheterization confirms
anatomic diagnosis &
physiologic derangement when
2-D PE is not consistent with the
ECHOCARDIOGRAPHY echocardiogram
• Used to evalu ate cardiac
contractile function – if LV is
functioning well (ex: decreased
when there are vegetations
[endocarditis])
• 2D-Echo is considered
confirmatory. Dapat secondary
to a finding ito like murmurs or
so.
• Displays blood flow in cardiac Lateral View
chambers and vascular channels
based on the change in OTHERS
frequency imparted to a sound 1. Electrocardiogram
wave by the movement of • A more sensitive and accurate index of ventricular
erythrocytes hypertrophy
DOPPLER • Colored Doppler – highly 2. Barium esophagogram
ECHOCARDIOGRAPHY accurate measurement of the • Delineates esophagus and great vessels in the initial
presence & direction of evaluation of suspected vascular rings
intracardiac shunts and

HawHaw 4 of 7
PEDIA2: PEDIATRIC CARDIOLOGY 2.3

3. CT • ~65% of descending aortic blood flow

• Adjunct to echocardiogram to evaluate extracardiac vascular o Returns to the placenta
morphology • ~35% perfusion
4. MRI o To fetal organs and tissues
• Quantitate ventricular volumes, cardiac function, and shunt • Any deviation or problem occurring in any part of fetal
and regurgitant fractions circulation will have an effect in the circulation of infant when he
comes out in the real world
NORMAL HEART DEVELOPMENT & PHYSIOLOGY • Presence of narrowing (stenosis) of an upstream structure such
CARDIAC MORPHOGENESIS as the mitral valve, flow downstream into the left ventricle is
• Early presomite embryo: 1st identifiable cardiac precursors limited and left ventricular growth may be compromised, leading
are angiogenetic cell clusters arranged on both sides of the to hypoplastic left heart syndrome
embryo’s central axis
FOUR FETAL SHUNTS IN FETAL CIRCLAION
AOG DESCRIPTION
18 days AOG • Clusters form paired cardiac tubes
• Primitive heart (Minsan akala ng mga babae
3 weeks AOG na missed menstruation lang, pero yun pala
may heart na si baby)
• Paired tubes fuse in the midline on the
22 days AOG ventral surface of the embryo to form the
primitive heart tube
• Embryonic heart begins to contract & exhibit
20-22 days phases of the cardiac cycle
• Heart tube begins to bend ventrally & toward
22-24 days the right (looping)
25 days • Septation of the ventricles
30 days • Septation of the atria
3 months • AV valve formation
9 months • Semilunar valves are complete
CAR
FETAL CIRCULATION
• Right & left ventricles exist in a parallel circuit
o Maintained by:
§ Ductus venosus
§ Foramen ovale
§ Ductus arteriosus
• Placenta
o Provides gas exchange & vessels in the pulmonary
circulation
o Due to this, the vessels are vasoconstricted
• Appearance of lung vessels:
o Vasoconstricted
§ When baby is delivered, the first gasp of air causes Fetal circulation shunts
expansion of pulmonary vessels • Shunts
• Oxygenated blood from placenta à 50% of umbilical venous o Primitive structures that are present and open in utero and
blood enters hepatic circulation à the other 50% bypasses eventually closes after birth
liver & joins IVC via DVà RA à FO à LA à LV à ascending
aorta SHUNTS DESCRIPTION
• Receives the largest amount of combined
ventricular output (55%)
Placenta • Has the lowest resistance in the fetus
• Its removal (once delivered) results in
increased systemic vascular resistance
Ductus • Removal of placenta from the circulation
Venosus result in its closure
• Between right and left atrium
• Most of the SVC blood goes to the RV
• About 1/3 of IVC blood is directed to the LA
Foramen through the FO
Ovale • 2/3 enters the RV and PA resulting in the
brain and coronary circulation receiving the
blood with higher 02 saturation
• High arterial p02 signals its constriction
which then becomes the ligamentum
Ductus arteriosum
Arteriosus • Shunt that is present only in the fetal life
• Persistently open - PDA

• Basically, all shunts will eventually close right after birth

• Fetal cardiac output
o The fetal heart is unable to increase stroke volume when
the HR falls because it has a low compliance.
o Depends on the HR
§ When the HR drops, a serious fall in CO results
Blood circulation in fetal heart • In the human fetus, which has a larger percentage of blood flow
going to the brain, right ventricular output is probably closer to
• Upper part of fetal body 1.3 times the left ventricular flow
o Perfused exclusively from the LV o The RV is not only pumping against systemic blood
§ With blood that has slightly higher pO2 than the blood pressure but is also performing a greater volume of work
perfusing the lower part of the fetal body (derived mostly than the LV
from the RV)
• Only a small volume of blood from the ascending aorta flows TRANISITIONAL CIRCULATION
across the aortic isthmus to the descending aorta CHANGES AFTER BIRTH
o 10% of fetal CO • The primary change after birth
• 450 ml/kg/min o Shift of blood flow for gas exchange from the placenta to
o Total fetal cardiac output the lungs
o Combined output of RV & LV • Interruption of the umbilical cord results in the following:

HawHaw 5 of 7
PEDIA2: PEDIATRIC CARDIOLOGY 2.3

o An increase in systemic vascular resistance • With expansion of the lungs and the resulting increase in
§ Due to removal of the low-resistance placenta alveolar O2 tension
o Closure of the ductus venosus o There is an initial, rapid fall in the PVR.
§ Result of lack of blood return from the placenta o This rapid fall is secondary to the vasodilating effect of O2
o Lung expansion on the pulmonary vasculature.
§ To do its function o Between 6-8 weeks of age
• Lung expansion results in the following: § There is a slower fall in the PVR and PA pressure
o Reduction of the pulmonary vascular resistance (PVR) § Murmur may not be heard at once and may take 6-8
o Increase in pulmonary blood flow weeks
o Fall in PA pressure • In acyanotic congenital heart problems like VSD, ASD, PDA
o Functional closure of the FO occurs • It takes several weeks before murmurs are heard
§ Due to increased pressure and volume in the LA • Significant differences between the neonatal circulation and
o Closure of PDA that of older infants include:
§ Result of increased arterial O2 saturation (ligamentum o right-to-left or left-to-right shunting may persist across the
arteriosum) patent foramen ovale
o LV plus high-resistance systemic circulation o in the presence of cardiopulmonary disease, continued
§ Wall thickness & mass increases patency of the ductus arteriosus may allow left-to-ring, right-
o RV plus low-resistance pulmonary circulation to-left, or bidirectional shunting
§ Wall thickness decreases o the neonatal pulmonary vasculature constricts more
• LV now must deliver the entire systemic CO vigorously in response to hypoxemia, hypercapnea, and
o Almost 200% increase in CO acidosis
• FUNCTIONAL CLOSURE o the wall thickness and muscle mass of the neonatal left and
o DA occurs by constriction of the medial, smooth muscle in right ventricles are almost equal
the ductus o newborn infants at rest have relatively high cardiac output
o Within 10-15 hours after birth • The newborn cardiac output (≈350 mL/kg/min) falls in the first
• ANATOMIC CLOSURE 2 months of life to approximately 150 mL/kg/min and then
o Completed by 2-3 weeks of age by permanent changes in more gradually to normal adult cardiac output of ≈75
the endothelium and subintimal layers of the ductus mL/kg/min
rd
• The responsiveness of the ductal smooth muscle to O2 is • Foramen ovale is usually functionally closed by the 3 month
related to the gestational age of the newborn of life
o Term: • Functional closure of the ductus arteriosus is usually
§ DA close spontaneously complete by 10-15 hr in a normal neonate
o Preterm: o May remain patent much longer in the presence of
§ Increase risk of PDA congenital heart disease, especially when associated with
§ The ductal tissue of a premature infant responds less cyanosis
intensively to oxygen than that of a full-term infant.
§ The premature infant’s ductal smooth muscle does not NORMAL BLOOD CIRCULATION
have a fully developed constrictor response to oxygen
§ This decreased responsiveness of the immature ductus
to O2 is due to its decreased sensitivity to O2-induced
contraction
§ It may also be due to persistently high levels of PGE2 in
preterm infants
Ÿ Removal of the placenta from the circulation also results in
closure of the ductus venosus
Ÿ LV is now coupled to the high-resistance systemic circulation
o Wall thickness and mass begin to increase
o Must deliver the entire systemic cardiac output(≈350
mL/kg/min)

Normal flow of blood

Unoxygenated blood (right side) enters RA à TV à RV à

Pulmonic valve à PA à lungs (for oxygenation),
Pulmonary vein, LA, mitral valve, LV, AV, aorta,
distributed to the systemic circulation

NEONATAL CIRCULATION
• Decrease in PVR usually occurs within 1st 2-3 days
o May be prolonged for 7 more days
st
• 1 several weeks of life:
o PVR decreases further
§ Due to remodeling of pulmonary vasculature
§ Includes thinning of the smooth muscle vessels and
recruitment of new vessels
o The reason why acyanotic heart problem do not readily
st
exhibit the murmur in the 1 several weeks kasi it takes time
before mag stabilize yung pag-decrease ng PVR
• Decrease in PVR
o Significantly influences the timing of clinical appearance of
CHD
§ Are dependent on the relative systemic and pulmonary
vascular resistance

HawHaw 6 of 7
PEDIA2: PEDIATRIC CARDIOLOGY 2.3

HawHaw 7 of 7