slide1 l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Pediatric Fundamentals – Heart and Circulation PowerPoint Presentation
Download Presentation
Pediatric Fundamentals – Heart and Circulation

Loading in 2 Seconds...

play fullscreen
1 / 11

Pediatric Fundamentals – Heart and Circulation - PowerPoint PPT Presentation


  • 286 Views
  • Uploaded on

Pediatric Fundamentals – Heart and Circulation. Embryology 1. Cardiovascular system begins forming at 3 weeks (diffusion no longer adequate) 2. Angiogenetic cell cluster and blood islands -> intraamniotic blood vessels 3. Heart tube 4. Heart begins to beat 22 – 23 days

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Pediatric Fundamentals – Heart and Circulation' - niveditha


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Pediatric Fundamentals – Heart and Circulation

Embryology

1. Cardiovascular system begins forming at 3 weeks

(diffusion no longer adequate)

2. Angiogenetic cell cluster and blood islands ->

intraamniotic blood vessels

3. Heart tube

4. Heart begins to beat 22 – 23 days

5. Heart looping -> 4 chambers, 27 – 37 days

6. Valves 6 – 9 weeks

slide2

Pediatric Fundamentals - Growth and Development

Cardiovascular system

In utero circulation

placenta ->

umbilical vein (UV)->

ductus venosus (50%) ->

IVC ->

RA ->

foramen ovale (FO) ->

LA ->

Ascending Ao ->

SVC ->

RA ->

tricuspid valve ->

RV (2/3rds of CO) ->

main pulmonary artery (MPA) ->

ductus arteriosus (DA) (90%) ->

descending Ao ->

umbilical arteries (UAs)->

slide3

Pediatric Fundamentals – Heart and Circulation

Transitional circulation

Placenta Out and Lungs In

PVR drops dramatically

(endothelial-derived NO and prostacyclin)

FO closes

DA closes

10-12 hours to 3 days to few weeks

prematures: closes in 4-12 months

PFO potential route for systemic emboli

DA and PFO routes for R -> L shunt in PPHN

slide4

Pediatric Fundamentals – Heart and Circulation

Persistent pulmonary hypertension of the newborn (PPHN)

Old PFC misnomer

Primary

Secondary

meconium aspiration

sepsis

birth asphyxia

Treatment

cardiopulmonary support

inhaled NO

ECMO

slide5

Pediatric Fundamentals – Heart and Circulation

Nitric oxide (NO) – cGMP transduction pathway

l-arginine

eNOS (endothelial NO synthetase)

oxidation of quanidine N moiety

NO

activates

GTP

sGC (soluble guanylate cyclase)

cGMP (cyclic-3’,5’-guanosine monophosphate)

activates

PDE (phosphodiesterase)

protein kinase

GMP

slide6

Pediatric Fundamentals – Heart and Circulation

Neonatal myocardial function

Contractile elements comprise 30% (vs 60% adult) of newborn myocardium

Alpha isoform of tropomyosin predominates

more efficient binding for faster relaxation at faster heart rates

Relatively disorganized myocytes and myofibrils

Most of postnatal increase in myocardial mass due to

hypertrophy of existing myocytes

Diminished role of relatively disorganized sarcomplasmic reticulum (SR)

and greater role of Na-Ca channels in Ca flux so

greater dependence on extracellular Ca

may explain:

Increased sensitivity to

calcium channel blockers (e.g. verapamil)

hypocalcemia

digitalis

slide7

Pediatric Fundamentals – Heart and Circulation

Myocardial energy metabolism

Young infant heart

lactate: primary metabolite

later: glucose oxidation and amino acids (aa’s)

metabolize glucose and aa’s under hypoxic conditions

(may lead to greater tolerance of ischemic insults)

Gradual transition to adult:

fatty acid primary metabolite by 1-2 years

slide8

Pediatric Fundamentals – Heart and Circulation

Normal aortic pressures

Wt (Gm) Sys/Dias mean

1000 50/25 35

2000 55/30 40

3000 60/35 50

4000 70/40 50

Age (months) Sys/Dias mean

1 85/65 50

3 90/65 50

6 90/65 50

9 90/65 55

12 90/65 55

slide9

Pediatric Fundamentals – Heart and Circulation

Adrenergic receptors

Sympathetic receptor system

Tachycardic response to isoproterenol and epinephrine

by 6 weeks gestation

Myocyte β-adrenergic receptor density

peaks at birth then

decreases postnatally

but coupling mechanism is immature

Parasympathetic, vagally-mediated responses are mature at birth

(e.g. to hypoxia)

Babies are vagotonic

slide10

Pediatric Fundamentals – Heart and Circulation

Normal heart rate

Age (days) Rate

1-3 100-140

4-7 80-145

8-15 110-165

Age (months) Rate

0-1 100-180

1-3 110-180

3-12 100-180

Age (years) Rate

1-3 100-180

3-5 60-150

5-9 60-130

9-12 50-110

12-16 50-100

slide11

Pediatric Fundamentals – Heart and Circulation

Newborn myocardial physiology

Type I collagen (relatively rigid) predominates (vs type III in adult)

Neonate Adult

Cardiac output HR dependent SV & HR dependent

Starling response limited normal

Compliance less normal

Afterload compensation limited effective

Ventricular high relatively low

interdependence

So:

Avoid (excessive) vasoconstriction

Maintain heart rate

Avoid rapid (excessive) fluid administration