disturbances

• Sinoatrial Node (SA node)


  Primary pacemaker of the heart, Inherent firing rate of 60 to 100 impulses per minute
• Atrioventricular Node (AV node)


  Located in the right atrial wall near the tricuspid valve, Coordinates the incoming electrical impulses from the atria and after a slight delay relays the impulse to ventricles, 40 to 60 impulses per minute
• Bundle of His

  Specialized conducting tissue, Right bundle branch - conducting impulses to the right ventricle, Left bundle branch - conducting impulses to the left ventricle, Divides into the left anterior and posterior bundle branches
• Purkinje fibers/ cells


  Terminal point in the conduction system, Specialized to rapidly conduct impulses through the thick walls of the ventricles, 30 to 40 impulses per minute
• Incidence of congenital heart defects: 1% of or about 40,000 births per year

  
• Most common anomaly is VSD
• 25% of babies with CHD are critical and generally needs surgery or other procedures in their 1st year of life (CDC)
• 15% of CHD are associated with genetic conditions
• 28% of kids with CHD have another recognized anomaly (trisomy 21,)
• Atrial Septal Defect (ASD)


  Abnormal opening between atria → blood from higher pressure (LA) to flow into lower pressure (RA), Increase O2 blood into R side of heart, RA & RV enlargement, Cardiac failure is unusual in uncomplicated ASD

  
• Atrial Septal Defect (ASD)

  • May be asymptomatic if small defect, Dyspnea, Fatigue and poor growth, Soft systolic murmur in pulmonic area (splitting S2), May develop CHF

  
• Diagnostic Exams for ASD

  2D Echo: reveals enlarged right side of the heart and ↑ pulmonary circulation, Cardiac catheterization: demonstrates separation of RA and the↑ O2 saturation in the RA

  
• Treatment for ASD

  Surgical treatment: Surgical Dacron patch closure, Open repair with C-P bypass during school age, Non-surgical: may be closed using devices during cardiac catheterization

  
• Nursing Management for ASD

  Explain to parents the purpose of tests and procedures, Teach parents ways to support nutrition, reduce stress on heart, promote rest, and support growth and development during preoperative period, Teach parents signs of congestive heart failure and infection, Prepare parents and child for surgery by visiting intensive care unit, explaining equipment and sounds, Prepare older child for post-operative experience, including coughing and deep breathing and need for movement, Teach need for antibiotic prophylaxis to prevent subacute bacterial endocarditis
• Ventricular Septal Defect (VSD)

  Defect in ventricular septum – error in early fetal development, Can occur anywhere in muscle or membranous ventricular septum, 20-25% of all CHDs are VSD

  
• Hemodynamics of VSD


  Pressure LV → RV and systemic arterial circulation resistance → pulmonary circulation, blood flows through the defect and into the pulmonary artery, RV becomes enlarged (Hypertrophied), over time the RA may also become distended

  
• Symptoms of VSD


  • Tachypnea, dyspnea, Poor growth, reduced fluid intake, Palpable thrills, Systolic murmur at left lower sternal border, May develop CHF
• Treatments for VSD


  Medications: Furosemide (diuretic), Digoxin (helps heart pump more forcefully), Angiotensin-converting enzyme (ACE) inhibitor (relaxes blood vessels and help heart to pump more easily), Surgical repair with bypass (procedure of choice), Pulmonary artery banding (if not too large) or patch
• Patent Ductus Arteriosus (PDA)

  Ductus SHOULD close by about age 15 hours after birth, Some shunting of blood may occur up to 24 hours of life, Prostaglandin E leads to closure of PDA, Allows blood to flow from left to right and pulmonary blood flow

  
• Symptoms of PDA


  • Small PDA: asymptomatic, Bounding peripheral pulses, Widened pulse pressure (>25), Loud machine-like murmur at upper left sternal border (Left intraclavicular area), Large PDA: CHF with tachypnea, dyspnea, and hoarse cry
• Diagnosis and Treatment of PDA

  Definitive diagnosis: ECHO, Medical (Premature) INDOMETHACIN to close PDA's, Surgical ligation if meds fail, Prophylactic antibiotics to prevent bacterial endocarditis, Surgery between age 1-2 years
• Obstructive Defects


  Blood flow in heart meets an area of anatomic narrowing (stenosis) → obstruction to blood flow, Pressure in ventricle & great arteries before obstruction is increased; pressure in area beyond obstruction is decreased, Location of narrowing near the valve: Valvular, Subvalvular, Supravalvular

  
• Coarctation of Aorta


  The aorta is narrowed near the insertion of the ductus arteriosus, Increased pressure proximal to the defect, Causes high BP & bounding pulses in arms; weak or absent femoral pulses, and cool lower extremities with low BP

  
• Signs of Coarctation of Aorta

  • In infants: Condition can deteriorate rapidly, In older kids: Dizziness, headache, fainting and epistaxis from hypertension, Patient at risk for ruptured aorta, aortic aneurysm, or stroke
• Treatment of Coarctation of Aorta

  Non-surgical - balloon angioplasty, Surgical: does not require bypass since defect is outside pericardium, Usually done before age 2 yrs, Risk of recurrence

  
• Aortic Stenosis


  Narrowing of aortic valve usually malformed in BI- rather than TRI-cuspid valve, Causes increased resistance in left ventricle, decreased CO, L ventricular hypertrophy and pulmonary vascular congestion, L ventricular wall is hypertrophied>> increased pulmonary vascular resistance & pulmonary hypertension, LVH >> decrease coronary artery perfusion & increase risk of MI

  
• Symptoms of Aortic Stenosis

  • Signs of decreased CO: faint pulses, hypotension, poor feeding, tachycardia, Murmur; exercise intolerance, Chest pain, dizziness with standing
• Treatment of Aortic Stenosis


  Balloon angioplasty to dilate the valve, Surgery: Konne procedure (valve replacement), May require repeat procedures
• Pulmonary Stenosis


  Pulmonary valve is stenosed, Narrowing at entrance to pulmonary artery >> R ventricular hypertrophy and decreased pulmonary blood flow, Extreme form: Pulmonary atresia (total fusion of the commisures and no blood flow to lungs), PS >> RVH, R ventricular failure >> R atrial pressure increases and may reopen foramen ovale, Shunts unoxygenated blood to L atrium >> systemic cyanosis, May lead to CHF, Often have PDA as well

  
• Treatment of Pulmonary Stenosis


  Balloon angioplasty to dilate the valve, Surgical treatment – Breck procedure (Bypass to do valvotomy), Usually can repair with catheterization
• Defects of Decreased Pulmonary Blood Flow

  Obstruction of pulmonary blood flow + anatomic defect (ASD/ VSD) between R & L side of heart, Difficulty of blood exiting R heart via pulmonary artery → increase R side pressure > L pressure → desaturated blood shunt R to L → desaturated blood in systemic circulation, Hypoxemia, usually cyanotic

  
• Tetralogy of Fallot


  Involves four heart defects: Ventricular Septal Defect, Pulmonary stenosis, Right ventricular hypertrophy, Overriding aorta, Hemodynamics vary widely depending on extent of pulmonic valve stenosis & size of VSD

  
• Symptoms of Tetralogy of Fallot

  • "TET SPELLS" or "blue spells" with acute episodes of cyanosis and hypoxia, Anoxic after feeding or with crying, RISK of emboli, LOC, sudden death, seizures
• Treatments for Tetralogy of Fallot

  Stage 1: Blalock or modified Blalock shunt >> blood to pulmonary arteries from L or R subclavian artery, Complete repair: usually in 1st year of life, Repair of VSD, resect stenosed area, and patch R ventricular outflow

  
• Tricuspid Atresia


  Failure of tricuspid valve to develop, No communication from R atrium to R ventricle, Blood flows thru an ASD or a patent FO to L side of the heart thru a VSD to R ventricle to lungs, Often associated with PS and TGS, Complete mixing unO2 and O2 blood in L side of the heart → systemic desaturation, pulmonary obstruction → decrease pulmonary blood flow

  
• Symptoms of Tricuspid Atresia


  • Cyanosis, tachycardia, dyspnea, hypoxemia, clubbing, At risk for bacterial endocarditis

  
• Repairs


  Usually indicated when Tet spells and hypercyanotic spells increase
• Stage 1: Blalock or modified Blalock shunt

  Blood to pulmonary arteries from L or R subclavian artery

  
• Complete repair


  Usually in 1st year of life. Repair of VSD, resect stenosed area, and patch R ventricular outflow
• Tricuspid atresia


  Failure of tricuspid valve to develop