Transcript Syncope

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Emergencies in pediatric
cardiology
Outlines
Cardiogenic shock
Approach to a cyanotic neonate
Arrhythmias
• Brady arrhythmias
• Tachyarrhythmias
Cardiogenic Shock
severe cardiac dysfunction before or after
cardiac surgery
septicemia
severe burns
anaphylaxis
cardiomyopathy
myocarditis
myocardial infarction or stunning
Central nervous system disorders
Cardiogenic Shock
Cardiomyopathy
Arrhythmias
Mechanical abnormality
Obstructive disorder
Treatment
Treatment is aimed at reinstitution of
adequate cardiac output and peripheral
perfusion to prevent the -untoward effects
of prolonged ischemia on vital organs, as
well as management of the underlying
cause.
Cardiac output in turn is
dependent on two cardiac factors
1) heart rate (HR) and
2) stroke volume (SV).
As children are "heart rate dependent",
the heart rate is the single most important
vital sign when determining shock.
Stroke volume is the second determinant of
cardiac output, and is dependent on three
factors:
1) preload (intravascular volume/blood often called
"venous return"), (the fuel),
2) myocardial contractility (heart muscle function), (the
pump), and
3) afterload (systemic vascular resistance) (the pipes).
Children are particularly dependent upon adequate
intravascular volume, and when volume depleted, they
peripherally vasoconstrict to maintain stroke volume. The
myocardium in infants is "stiff" and plays little role in
increasing cardiac output. Therefore, the heart rate must
increase in order to maintain adequate circulatory
function. Remember
C.O.=H.R. x S.V
Preload
Optimal filling pressure is variable and
depends on a number of extracardiac
factors including ventilatory support with
high positive end-expiratory pressure and
intra-abdominal pressure.
The increased pressure necessary to fill a
relatively noncompliant ventricle should
also be considered
Preload
The mean difference between CVPs
measured from the central and peripheral
catheters was 8 ± 4 cm H2O.
The linear regression equation showed :
CVP = 0.32 PVP + 3.8 (r = 0.67; p<0.005).
H. Amoozgar, N. Behniafard, M. Borzoee ,G. H. Ajami. Correlation Between
Peripheral and Central Venous Pressures in Children with Congenital Heart
Disease. Pediatr Cardiol (2008) 29:281–284
Contractility
Dopamine, epinephrine, and dobutamine
improve cardiac contractility
The use of cardiac glycosides to treat
acute low cardiac output states should be
avoided
Afterload
Patients in cardiogenic shock may have a
marked increase in systemic vascular
resistance resulting in high afterload and
poor peripheral perfusion
Milrinone & nitroprusaid
Blood pressure
measurement in
neonates
Blood pressure measurement in neonates
Blood pressure measurement in neonates
Blood pressure measurement in neonates
the measured BP is 9 mm Hg higher than
pulse method.
In 86-92% of neonate the measured BP by
pulse had only 10 mm Hg difference with
BP by pulse oximetry.
H. Amoozegar, M.Rastegar . Comparison of neonatal blood pressure
measurement by pulse-oximetry and conventional method (Pulse)
Iran J Pediatr, Vol 16, No 3, Sep 2006
Stages
Disturbance of perfusion
End organ damage
Irreversible shock
Death
Evaluation and initial
management of cyanotic
heart disease in the
newborn
Cyanosis
HISTORY
Family history
Prenatal testing
Perinatal history
PHYSICAL EXAMINATION
Vital signs
Second heart sound
Murmur
Hepatomegaly
LABORATORY STUDIES
Complete blood count
Sepsis evaluation
Chest radiograph
Electrocardiogram
Oxygen saturation
Arterial blood gas
Hyperoxia test
Echocardiography
INITIAL MANAGEMENT
General approach
Antibiotics
Prostaglandin E1
Cardiac catheterization
Hypercyanotic Episodes and
Squatting
severe and often prolonged decrease in
arterial saturation
The cyanosis is a result of an acute,
substantial increase in right-to-left
shunting owing to a change in the ratio
between pulmonary and systemic vascular
impedance.
They tended to occur more commonly in
patients with iron deficiency anemia
changes in the degree of subpulmonic
Treatment
Knee chest position
O2 2L/Min
Hydration 20 cc/Kg
Morphine 0.2 mg/Kg
Bicarbonate 1 meg /KG
Propranolol 0.01-0.1 mg/KG
Phenylephrine
Arrhythmias
Brady arrhythmia
Abnormalities of impulse propagation
and/or inhibitory neural influence in the AV
conduction system may result in
abnormalities including intra-atrial block,
block within the AV node, block within the
His, or aberrant ventricular conduction
owing to block within one of the
specialized intraventricular fascicles.
Management
Treatment for sinus node dysfunction
depends on symptoms, which may include
syncope, exercise intolerance, and/or
cardiac dysfunction aggravated by loss of
AV synchrony, all of which are treated with
pacing.
Isoperoteranol (B1,B2 agonist)
0.05-2 mac/Kg/Min
Pacing
Supraventricular tachycardias
(SVTs)
categories:
• re-entrant tachycardias using
an accessory pathway
• Re-entrant tachycardias without an
accessory
• pathway, and ectopic or automatic
tachycardias
CLINICAL MANIFESTATI0N
The heart rate usually exceeds 180 beats/min
and may occasionally be as rapid as 300
beats/min
The only complaint may be awareness of the
rapid heart rare.
ECG
SVT may occur in the presence of
unoperated congenital heart disease (Ebstein
anomaly).
In children, SVT may be precipitated by
exposure to the sympathomimetic amines
contained in over-the-counrer decongestants
associated with abnormal hearts
(cardiomyopathy) or with posroperative
congenital heart disease
Differentiation from sinus
tachycardia
Differentiation from sinus tachycardia may
be difficult; if the rate is >230 beats/min
with an abnormal P-wave axis (a normal P
wave is positive in leads I and aVF)
TREATMENT
Vagal stimulation by submersion of the
face in iced saline (in older children) or by
placing an ice bag over the face (in
infants) may abort the attack
To abolish the paroxysm, older children
may be taught vagotonic maneuvers such
as the Valsalva maneuver, straining,
breath holding, drinking ice water, or
adopting a particular posture.
Pharmacologic
In stable patients, adenosine by rapid
intravenous push is the treatment of
choice because of its rapid onset of action
and minimal effects on cardiac
contractility.
Adenosine 0.1-0.2 mg/Kg over 1-2
sec(Max 0.25 Mg/Kg up to 12 Mg)
DC cardio version
when symptoms of severe heart failure
have already occurred, synchronized DC
cardio version (0.5-2 W-sec/kg) is
recommended as the initial management
maintenance therapy
In patients without an antegrade accessory
pathway, digoxin or propranolol is the
mainstay of therapy.
In children with evidence of preexcitation
(WPW syndrome) digoxin or calcium channel
blockers may increase the rate of
anterograde conduction of impulses through
the bypass tract and should be avoided.
Radiofrequency ablation
Ventricular tachycardia
Ventricular tachycardia (VT) is less
common than SVT in pediatric patients.
VT is defined as at least three PVCs at
>120 beats/min
Treatment
For patients who are hemodynamically
stable, intravenous amiodarone, lidocaine,
or procainamide are the initial drugs of
choice.
Lidocaine 1 mg/Kg slowly IV *2 times 15
min and then 20-50 mcg /Kg/Min
ETT Dose 2-2.5* IV
Amiodarone 5-10 mg/Kg over 30 min
DC shock
when symptoms of severe heart failure
have already occurred, synchronized DC
cardioversion (4 J/kg) is recommended as
the initial management
Unless a clearly reversible cause is
identified, electrophysiologic study is
usually indicated for patients in whom VT
has developed