Disturbances in Circulation

Disturbances in Circulation Notes

Overview of Fetal and Neonatal Circulation

  • Fetal Circulation:
    • Important structures:
    • Ductus Arteriosus: Connects pulmonary artery to aorta; becomes Ligamentum arteriosum after birth.
    • Foramen Ovale: Connects right and left atrium; becomes Fossa ovalis after birth.
    • Ductus Venosus: Connects umbilical vein to inferior vena cava; becomes Ligamentum venosum.
    • Oxygenated blood arrives from placenta via the umbilical vein.
    • Deoxygenated blood returns through umbilical arteries to placenta.

Heart Conduction System

  • Key Components:
    • Sinoatrial Node (SA node): Primary pacemaker; 60-100 impulses/min.
    • Atrioventricular Node (AV node): Coordinates impulses; 40-60 impulses/min.
    • Bundle of His: Conducts impulses to RV and LV through right and left branches.
    • Purkinje Fibers: Terminal points for quick impulse conduction through ventricles; 30-40 impulses/min.

Congenital Heart Defects (CHDs)

  • Incidence: 1% or about 40,000 births/year.
  • Common Anomalies:
    • Ventricular Septal Defect (VSD) is the most common.
    • 25% of CHDs require procedures in the first year.
    • 15% associated with genetic conditions.

Classification of CHDs:

  1. Acyanotic:
    • Obstruction of blood flow (e.g., Coarctation of aorta, Aortic Stenosis).
    • Increased blood flow to the lungs (e.g., ASD, VSD).
  2. Cyanotic:
    • Mixed blood flow (e.g., Tetralogy of Fallot, Transposition of Great Arteries).

Detailed Examples of Congenital Heart Defects:

Atrial Septal Defect (ASD)
  • Abnormal opening between atria; increased blood flow to right side.
  • Symptoms: Asymptomatic to fatigue, dyspnea, and a soft systolic murmur.
  • Diagnostics: 2D Echo shows enlarged right heart; catheterization measures O2 levels.
  • Treatment: Surgical closure (patch) or device closure via catheter.
Ventricular Septal Defect (VSD)
  • Defect leads to shunting of blood from left to right ventricle.
  • Symptoms include tachypnea, poor growth, and loud murmur.
  • Treatment: Diuretics, surgical repair with patch or sutures.
Patent Ductus Arteriosus (PDA)
  • Ductus should close but remains open, leading to increased pulmonary blood flow.
  • Symptoms: May be asymptomatic or present with bounding pulses and a characteristic machinery-like murmur.
  • Treatment: Indomethacin for closure; surgical ligation if needed.
Coarctation of Aorta
  • Narrowing of the aorta, causing increased BP proximal and decreased distal.
  • Symptoms: High BP in arms, weak femoral pulses, cool extremities.
  • Treatment: Balloon angioplasty or surgical resection.

Acquired Cardiovascular Disorders:

Congestive Heart Failure (CHF)
  • Heart's inability to pump adequate blood causing various symptoms.
  • Right-sided failure: Increased RA pressure, systemic venous congestion.
  • Left-sided failure: Increased LA pressure, pulmonary congestion.
  • Symptoms include tachycardia, fatigue, poor feeding, and pulmonary congestion.
  • Treatment Goals:
    • Improve cardiac function (digitalis), decrease fluid overload (diuretics), manage CHF symptoms.
Endocarditis
  • Infection of heart valves and endocardium.
  • Caused by various pathogens; common enters through dental procedures.
  • Clinical Manifestations: Fever, malaise, embolic phenomena (Osler nodes, Janeway lesions).
  • Treatment: High-dose IV antibiotics; prophylaxis for high-risk patients.

Rheumatic Fever (RF) and Rheumatic Heart Disease (RHD)

  • Complications due to post-streptococcal infection leading to heart valve damage.
  • Major criteria: Carditis, polyarthritis, erythema marginatum, chorea.
  • Treatment: Antibiotics, aspirin for inflammation, long-term follow-up.

Kawasaki Disease

  • Mucocutaneous lymph node syndrome in children <5 years.
  • Highly inflammatory; can lead to coronary artery aneurysms.
  • Symptoms: Persistent fever, conjunctival injection, rash, lymphadenopathy.
  • Treatment: IVIG and aspirin to manage inflammation and prevent coronary damage.

Cardiac Function Tests

  • Echocardiography: Visualizes heart shadowing for structural defects.
  • EKG: Assesses electrical activity; used for rhythm abnormalities.
  • Cardiac Catheterization: Diagnostic and therapeutic for congenital defects.