Cardiology

Transposition of Great

Arteries (TGA)
• Account for 5% of all CHD
• It is the most common cyanotic disease present in the neonatal period.
• In TGA the aorta arises from Rt ventricle
• Pulmonary artery arises from the Lt ventricle.

• This will result in:

• Desaturated blood return to the Rt side of the heart and pumped back to the body via the aorta
• Oxygenated blood from the lungs enter the Lt side of the heart and pumped back to the lungs via the pulmonary artery.

• Death occurs shortly after birth without mixing of the tow circulations.

• This mixing may occurs in atrial level (through a patent foramen ovale or ASD)
• Or at ventricles (through a VSD)
• Or at great vessels (through PDA).


• Cyanosis is always present and its severity depend on the amount of mixing between systemic and arterial circulations.
• Tachypnea.
• Single S2, and if there’s no VSD there’s no murmur.
Clinical Features:

• Children with TGA and large VSD may present with signs of heart failure with:

• palpable Lt and Rt V impulses
• single S2 and load VSD murmur (pansystolic murmur).

ECG: shows Rt axis deviation and RVH.

CXR:
• increase pulmonary vascularity
• egg on a string caused by narrow superior mediastinum.
Diagnosis:

Echocardiography:

• transposition of great artery
• site and amount of the shunt
• any associated anomalies.


• Prostaglandin E1 infusion immediately after birth to maintain the patency of ductus arteriosus and allow mixing of the blood.
• Balloon atrial septostomy done if there’s no response to prostaglandin infusion.
• Complete surgical repair by arterial switch operation. It is usually done within the first 2 weeks of life.
Treatment:

Acquired Heart Diseases

Infective Endocarditis (IEC):
• Acute and subacute bacterial endocarditis
• Non-bacterial endocarditis caused by viruses, fungi and other microorganisms.
• It is a significant cause of morbidity and mortality in children and adolescents.

Vascular endothelium damage

Pathogenesis:
Jet streams of turbulent blood (from PDA, VSD, or systemic-pulmonary shunt)
Nonbacterial thrombotic embolus

• Prior congenital or rheumatic heart diseases.

• Preceding dental, urinary tract or intestinal procedures.
• Intravenous drug use.
• Central venous catheter.
• Prosthetic heart valve.
Predisposing factors:


• Streptococcus Viridans
• Staphylococcus aureus
Causative MO (Etiology):
• Other: St. pneumoniae, H. influenzae, coagulase-negative staphylococci and fungi are less common.
• Blood culture is negative in about 6% of cases

the most

common

Symptoms:

• Early: mild prolonged fever with occasional weight loss.
• Or acute and sever onset with high intermittent fever and prostration
• “nonspecific” : fatigue, myalgia, arthralgia, headache, chills, nausea and vomiting, chest and abdominal pain, dyspnea, night sweating and CNS (stroke and seizures).
Clinical Features:

• Elevated body temperature.

• Tachycardia.
• Petechiae.
• New or changing heart murmur.
• Splenomegaly.
• Signs of heart failure and arrhythmias.
• Clubbing.
• Metastatic infections (Arthritis, meningitis, Mycotic arterial aneurysm, pericarditis, abscesses)
Clinical signs:


• Classical skin signs: later in the course of the disease and they may be vasculitis caused by circulating Ag-AB complexes. These signs are:

• Osler nodes (tender,

pea-size intradermal nodules
in the pads of the fingers
and toes)




• Janeway lesions (painless small erythematous or hemorrhagic lesions on the palms and soles).

• Splinter hemorrhages (linear lesions beneath the nails).

1. Blood culture:
• Is the main way for confirmation of IEC.
• 3-5 blood samples should obtained after perfect sterilization of skin.
• Causative agent is recovered from the first 2 blood cultures in 90% of the cases.
• The bacteremia is low grade in 80% of cases (<100 colony units\ ml of blood).
Diagnosis:

• Elevated ESR and C-reactive protein.

• CBC: anemia and leukocytosis.
• Immune complexes detection.
• Positive rheumatoid factor.
• GUE: hematuria.
• Echocardiography shows evidence of valve vegetation, prosthetic valve dysfunction, myocardial abscess, and new-onset valve insufficiency.

• Heart failure (most common) due to aortic or mitral vegetations.

• Systemic emboli: CNS and pulmonary.
• Mycotic aneurysm.
• Valvular obstruction by large vegetation.
• Acquired VSD.
• Heart block due to involvement of conducting system.
Complications:


• Other complications: meningitis, osteomyelitis, arthritis, renal abscess and immune complex-mediated GN.

• Antibiotic therapy immediately once the diagnosis is made.

• Empirical antibiotic therapy include:
• Vancomycin (40mg\kg\24 hr in 2-3 divided doses)
• Plus Ceftriaxone (100mg\kg\24 hr once a day).
Treatment:

• Antibiotic therapy should continue for 4-6 weeks and modified according to the blood culture results
• If the cause is St. Viridans :
• crystalline penicillin G (200,000 IU\kg\day) or ceftriaxone
• If the patient is sensitive to penicillin: ceftriaxone plus gentamycin or Vancomycin.

• If the cause is staphylococci:

• naficillin or oxacillin for 6 wk plus gentamycin for 3-5 days (optional).
• If the patient is allergic to penicillin: ceftazolin for 6 wk plus gentamycin for 3-5 days (optional).
• If the patient is infected by oxacillin-resistance strains : Vancomycin for 6 wks.

• Treatment of heart failure by:

• diuretics
• after load reducing agents
• digoxin.


Prevention:
• Indicated only before dental procedures in patient with:
• Prosthetic cardiac valve.
• Previous IEC.
• Congenital heart diseases:
• Unrepaired cyanotic CHD including palliative shunts.

• Completely repaired CHD with prosthetic materials during the first 6 mo after the procedure.
• Repaired CHD with residual defect at the site or adjacent to the prosthetic device.
• Cardiac transplant recipients.
• Permanently damaged valve by rheumatic heart disease.

• Oral amoxicillin 50 mg\kg.

• If the patient is unable for oral intake:
• Ampicillin 50mg\kg IM or IV
• Or Ceftriaxone 50mg\kg IM or IV
• Patients allergic to penicillin and able for oral intake:
• Cephalexin 50 mg\kg
• Or clindamycin 20mg\kg.
• Or Azithromycin or clarithromycin.
Prophylactic antibiotic regimens for dental procedures:


• Patients allergic to penicillin and unable for oral intake:
• Ceftriaxone 50mg\kg IM or IV.
• Or clindamycin 20mg\kg IM or IV.

• Mortality rate 20-25%

• Serious morbidity occur in 50-60% despite of antibiotic therapy.
Prognosis:
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