Cardiac Introduction

Notes on how the heart works...


The cardiac system develops first. It is nearly complete by 8 weeks gestation. Basically the heart is a 4-chambered structure that corresponds to the size of the child’s fist. The atria are the reservoirs, think of them as filling stations and the ventricles as the pumps. Remember the right chamber drives the blood into the low resistance pulmonary artery (1 of the great vessels) and on into the lungs. This is the only artery that carries deoxygenated blood. The left ventricle is high pressure because it pushes the blood into the high resistance systemic circulation via the aorta (the other great vessel). Remembering these basic pathways will help recognize the symptoms produced by the various abnormalities.




There is also an electrical system that initiates the mechanical activity of the heart but for this lecture we are just going to concentrate on the changes produced by structural defects.

* Fact a child's heart is about the size of their fist. This ratio continues to adulthood.*

*Forty percent of all heart malformations are diagnosed within the first year of life.* A detailed history is important:

History:
Maternal pregnancy history - drugs, medications, alcohol, infections, exposures to viruses, illnesses
Feeding patterns - feeding is exercise, do they tire, poor feeding, diaphoresis
Growth patterns - poor weight gain
Illnesses - frequent respiratory infections
Symptom history – SOB, fatigue, cyanosis

Physical Assessment and Inspection:
Respirations
Cry or speech patterns
Skin Color, nail beds, cyanosis, when, where, check lips and tongue
Activity level
Physical abnormalities
Dysmorphic facial appearance
Edema
Chest wall malformations
Clubbing of fingers
Palpation for hepatomegaly- liver enlargement can be associated with CHF


Murmurs
graded I-VI
Not all are pathologic, some are innocent


Blood Pressure:

Blood pressures factor in age, height and weight,

Can be useful to determine coarctation of the aorta, use the right arm and either leg, normally the leg bp is equal to or greater than the arm.

Pulsus paradoxus - the systolic blood pressure drops more than 10 mm Hg with inspiration indicates inadequate heart filling from tamponade (accumulation of fluid around the heart), pericardial effusion (collection of fluid in the pericardial sac), pericarditis (inflammation of the pericardium).

Diagnostic tests: used to diagnose and evaluate a child’s heart include:
Pulse oximetry
Electrocardiogram - ECG
Holter monitor - 24-48 hours
Event monitoring - month
Chest x-ray - CXR
Echo cardiogram – ECHO-
Magnetic resonance imaging – MRI
Cardiac catherization

Echo – nursing interventions
valves, septal defects, malformations
sound waves, < 2 sedation, monitor pulse oximetry, heart rate, warm ultrasound gel

Cardiac Catherization – nursing interventions
Prior ECG, ECHO, CBC, platelet count,
NPO, height, weight, allergy status (particularly latex so can be pre-medicated with Benadryl and steroids, iodine from contrast dyes)
Baseline pedal pulses and pulse oximetry
Child life specialists – preparation, tour, age appropriate language

Cardiac Cath. Post-Op Care
Temperature, color, pulse of extremity
Q 15 minute vital signs, then Q 1 hour
Intake and Output, contrast can promote diuresis
Observe for bleeding, hematoma, if bleeding pressure, call Dr.
Oxygen saturation, compare to baseline

Cardiac Cath. Later-
Child in bed with affected extremity straight for 4-8 hours
Younger child can be held by caregiver
Diet advanced as tolerated
Pressure dressing removed in 24 hours, no sand bags

Cardiac Cath. Discharge teaching-
Site care
Observe for signs and symptoms of infection
Monitor for fever
Restrict strenuous activities for 48-72 hours
Acetaminophen or Ibuprofen for pain

Knowing how a normal heart performs is essential to understanding the results of a defect!








Signs and symptoms...


Problems can lead to congestive heart failure











With the cardiac patient or defects given as a group collaborate:

Name some nursing diagnoses and outcomes.

Plan and discuss possible nursing interventions for your cardiac patient.

What tests will the patient need?

What symptoms might they display?

What family teaching topics are needed?

Defects with increased pulmonary blood flow and CHF, primarily acyanotic:

Atrial Septal Defect (ASD)
Ventricular Septal Defect (VSD)
Patent Ductus Arteriosus (PDA)
Atrioventricular Septal Defect
Truncus Arteriosus

Pathology:
These cause shunting of blood from the left to the right side of the heart.
These cause clinical symptoms of Congestive Heart Failure

Clinical Manifestations of Congestive Heart Failure - Newborns/ Infants:
Tachycardia
Tachypnea
Gallop rhythm
Retractions
Diminished pulses
Wheezing
Cool, mottled extremities
Hepatomegaly
Pallor
Low urine output
Edema
Failure to thrive
Restlessness

Clinical manifestations of Congestive Heart Failure – Children/ Adolescents:
Jugular vein distention
Tachycardia
Wheezing
Gallop rhythm
Rales or rhonchi
Diminished pulses
Dyspnea
Pallor
Orthopnea
Edema
Hepatomegaly
Low urine output
Ascites
Exercise intolerance
Poor weight gain

Treatments:
Reduce volume overload (Diuretics)
Improve contractility, reduce rate and work, positive inotropes, (Digoxin)
Angiotensin-converting enzyme (ACE) inhibitors, Vasodilation, decrease resistance

*Must check Potassium levels before can administer digoxin*

*Digoxin*
  • use syringe, not dropper
  • Check apical pulse for 1 full minute
  • Do not give if pulse is below 90-110
  • Check Potassium level to avoid hypokalemia (arrhythmias)
  • Decrease potassium enhances digoxin
  • If miss dose > 4 hours wait till next dose, < 4 hours give
  • Notify Dr. if loss of appetite, nausea, vomiting, diarrhea, abdominal pain or visual changes
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Notes on Atrial Septal Defects (ASD):
Abnormal connection between the right and left atria
Accounts for 6-10% of heart defects
Acyanotic defect
Easily missed

Pathology:
Blood flows from left to right side of the heart
This increases volume in the right atria, ventricle and pulmonary artery
Enlarging the right atria, ventricle and pulmonary artery

Clinical Manifestations:
Asymptomatic
Systolic murmur
Chest x-rays indicate an enlarged heart
Echo
No cardiac cath. necessary

Treatment:
Diuretics
Surgery when school age because it may close in first 2 years
Cardiac Cath. Used to thread an occlusive device





Notes on Ventral Septal Defect (VSD):
Hole between the right and left ventricles
One of the most common congenital heart defects
Accounts for 50% of heart defects alone or in combination
Blood shunts through defect left to right, overloads pulmonary artery leading to pulmonary congestion and right heart enlargement.
Small defect may be asymptomatic

Moderate to large defect produces signs of CHF:
  • Tachypneic
  • Diaphoretic
  • Fatigues easily

Usual tests:
  • Listen for a Murmur
  • X-ray
  • Echo, not cardiac cath.

*Small VSD no treatment 75-80% will close spontaneously

Large defects treated for the first few months for CHF
  • Digoxin
  • ACE inhibitors
  • Diuretics
  • High calorie feeding
  • Nasogastric tube if too tired

Surgical repair is between 3 and 12 months of age. Stitched or patched, sometimes patched during a cardiac catherization.



Truncus Arteriosus

Single arterial trunk gives rise to pulmonary arteries, the aorta and the coronary arteries
Approximately 1.4 % often with DiGeorge syndrome (Thymus and Parathyroid)

Pathophysiology:
Oxygenated and unoxygenated blood flow from the ventricles into the common trunk, then to pulmonary circulation and systemic circulation.

Clinical Manifestations:
Mildly cyanotic
Later CHF
Murmur

Diagnosis:
Chest x-ray
Echo
Cardiac Cath

Treatment:
Surgery in first 1-2 weeks of life


Normal_Heart_by_childheartspecialist.com.jpg Truncus_by_childheartspecialist.com.jpg

These two drawings are from child heart specialist.com. You can see the right and left ventricle form a common trunk before separating into the aorta and the pulmonary artery. This causes the oxygenated blood and unoxygenated blood to mix.


References:
O'Brien, P., & Baker, A. L. (2009). Chapter 25: The child with cardiovascular dysfunction. In M. J. Hockberry & D. Wilson (Eds.), Wong's essentials of pediatric nursing (8th ed., pp. 861-910). St. Louis, MO: Mosby Elsevier.

Videos:
VSD video located at http://youtu.be/w-iiD6aeZOY
Normal heart and truncus located at child heart specialist.com