Cardio - 3 Flashcards
What are the risk factors for subacute bacterial endocarditis?
In children:
Unlike in acute endocarditis, an underlying valvular heart disease is needed for streptococcus viridans to cause infection of the valve
Also VSD and ASD
Previous Hx of SBE
In adults, there are others such as valve surgery and IVDU
What are the causes for subacute bacterial endocarditis?
Normally streptococcus viridians (in mouth - dentition)
Also streptococcus intermedius
Less often:
enterococci (eg. from UTI)
Staphylococci
(gastro or pelvic procedures)
What is the management for subacute bacterial endocarditis?
If untreated, it can become fatal within 6weeks to a year
Minimum 4 weeks of iv penicillin + (aminoglycoside eg. gentamycin)
Rarely, valve repair/replacement via surgery.
What are the causes of myocarditis?
Viral infections (parvovirus B19, human herpes virus 6, enterovirus coxsackie virus)
Associated with respiratory tract infections.
Lyme disease
Autoimmune
Toxins (cocaine, metal, snake poison)
ADRs
What are the presenting features of myocarditis?
Usually signs and symptoms of acute decompensation of heart failure: tachycardia, gallop,mitral regurgitation, edema
SOB during exercise
Later also when sleeping
Fever, sweats, chills
Palpitations, syncope and even sudden cardiac death may develop! (20% of sudden death in young adults)
In viral myocarditis, there may be previous URTI, flu-like syndrome, arthralgia, tonsillitis
What is hypoplastic left heart syndrome?
Underdevelopment of entire left heart.
Mitral valve atretic, LV small, aortic valve atretic
Almost always with coarctation
What are the features of hypoplastic left heart syndrome?
Duct-dependent circulation
Profound acidosis +
Circulatory collapse around day 2 (duct closes)
Peripheral pulses absent/weak
How is hypoplastic left heart syndrome managed?
It is a duct-dependent lesion:
ABC
Prostaglandin infusion
Operations:
Norwood - Sano procedure (aorta connected to RV + huge Sano shunt from RV to pulmonary tree = provides circulation to body and lungs. Only works due to the presence of ASD)
Glenn at ca. 6 months (SVC connected to pulmonary tree and opening closed up)
Fontan at 3 years (IVC closed up and also connected to pulmonary artery). At this point, there is no mixing of oxygenated and unoxygenated blood - only oxygenated. Uses 1 ventricle.
What are the key features of Tetralogy of Fallot? (right-to-left shunt).
4 defects:
Pulmonary stenosis RV hypetrophy (as a result of pulmonary stenosis)
Large VSD
Overriding Aorta
Blood from RV is more likely to enter Aorta than pulmonary artery (due to stenosis). Cyanosis
Also, RV too powerful and pushes blood across into LV
Loud, harsh ejection systolic murmur at left sternal edge from day 1. Usually picked up antenatally
What are characteristics of cyanotic spells? (eg in tetralogy)
rapid cyanosis, irritability, inconsolable crying because of severe hypoxia.
SOB/pallor because of acidosis.
Very short murmur
What is the infant management of Tetralogy of Fallot?
If very cyanosed: shunt - to increase pulmonary blood flow.
A modified Blalock-Taussig (BT) shunt is a tube placed between the subclavian artery and the pulmonary artery.
Describe complete correction of tetralogy of Fallot
In infancy (6 months??) Most babies nowadays, apart from babies who are too weak to tolerate it.
Widen pulmonary valve (ballon or replaced)
Patch VSD
Describe the parallel circulation and duct-dependence in transposition of great arteries
Pulmonary artery connected to LV
Aorta connected to RV
Unoxygenated blood pumped straight into the body, whereas oxygenated blood returns to the lungs
Means that there are 2 closed off circuits. A patent ductus arteriosus is required to pump oxygenated artery into the body! CYANOTIC
Often, there is concurrent VSD or ASD, so some blood mixes.
What is the immediate management of TPA?
Prostaglandin
Balloon atrial septostomy life-saving and required in 20%
A catheter with an inflatable balloon is passed through umbilical vein or femoral into RA and through foramen ovale. Balloon is inflated in LA and pulled back through atrial septum. Renders flap of foramen ovale incompetent and allows mixing of pulmonary venous and systemic blood.
Describe the arterial switch procedure (needed in all patients with TPA)
Usually performed in the first few days of life.
Pulmonary artery and aorta transsected above the arterial valves and switched over.
The coronary arteries also need to be transferred over to the new aorta
