Cardiology Notes

Cardiology

8 per 1000 live born infants have some significant cardiac malformation

1-2% of live births have some abnormality of the CV system

The 9 common abnormalities listed below accoount for 80%

Left to Right Shunts (Breathless)

• VSD

• Persistent arterial duct (pulmonary aa to aorta reverses when pulmonary R falls)

• Atrial septal defect

Right to Left Shunts (Blue)

• Tetralogy of Fallot

• Transposition of the great arteries

Common Mixing (Breathless and Blue)

• Atrioventricular septal defect (complete)

Outflow Obstruction in a WELL Child (asymptomatic with a murmur)

• Pulmonary stenosis

• Aortic stenosis

Outflow Obstruction in a SICK Neonate (collapsed with shock)

• Coarction of the aorta

• (Hypoplastic LH syndrome)

Circulatory Changes At Birth

• In the fetus the LA pressure is low very little blood returns from the lungs

• Pressure in the RA is higher receives the systemic venous return (including blood from the placenta)

• Flap valve of the foramen ovale is held open and blood flows into the LA and hence the LV

• With the first breath pulmonary resistance falls and the volume of blood flowing through the lungs increases

  • Rise in LA pressure

• Volume of blood returning to the RA falls due to exclusion of the placenta

• Flap valve of the foramen ovale closes

• Ductus arteriosus connects the pulmonary artery and aorta in fetal life closes within the first few hours/days of life

  • Some circulations are duct dependent and a deterioration will be seen upon closure

    • Rx postaglandins maintain duct

Presentation of Congenital Heart Disease

• Will be detected due to one of the following:

  • Antenatal

  • Murmur

  • Heart failure

  • Shock

  • Cyanosis

Antenatal Diagnosis

• Fetal anomaly scan around 18-20 weeks

• 70% of infants who will require surgery within the first 6 months of life are diagnosed

• Abnormality or increased risk identified fetal echo

Heart Murmurs

• 30% of children have an innocent murmer

• Hallmarks of an innocent murmur:

  • ASymptomatic

  • Soft blowing

  • Systolic only

  • Left Sternal edge

• Also

  • Normal heart sounds, non added

  • No parasternal thrill

  • No radiation

  • Innocent murmurs common during illness and situations of increased CO

• Pathological Murmurs

  • All diastolic

  • All pansystolic

  • Late systolic

  • Loud (>3/6)

  • Continuous

  • Abnormal clinical findings

• NB; conditions such as VSDs or ductus arteriosus may only become apparent at several weeks of age when the pulmonary vascular resistance falls

Heart Failure

• Symptoms

  • Increased compensatory sympathetic drive

    • SOB

    • Sweating

    • Tachypnoea/tachycardia

  • Poor feeding

  • Recurrent chest infections

  • Symptoms of poor tissue perfusion fatigue, poor exercise tolerance and confusion

• Signs

  • Poor weight gain

  • Tachypnoea

  • Tachycardia

  • Heart murmur, Gallop rhythm

  • Cardiomegaly, Hepatomegaly

  • Cool peripheries

  • (Typically few signs of systemic congestion as observed in adults)

• Diagnosis CXR, echo, ECG, arterial blood gase

• Rx rest in semi recumbent position, O₂, diuretics, digoxin, vasodilators

• In the first week of life typically left heart obstruction (coarction. Etc.)

  • Arterial perfusion may be predominantly by R to L flow of blood duct dependent systemic circulation

• After the first week of life likely L to R shunt

  • As pulmonary resistance falls, progressive increase in L to R shunt

  • Pulmonary oedema and SOB

  • May subsequently improve as pulmonary vascular resistance rises in response to the L to R shunt

    • Untreated = Eisenmenger syndrome irreversibly raised pulmonary vascular resistance

      • Now the shunt is from R to L and the teenager is blue

        • Rx Heart lung transplant

• Neonates obstructed (duct dependent) systemic circulation

  • Hypoplastic left heart syndrome

  • Critical aortic valve stenosis

  • Severe coarction

  • Interruption of the aortic arch

• Infants (high pulmonary blood flow)

  • VSD

  • Atriventricular septal defect

  • Large persistent ductus arteriosus

• Older children and adolescents (R or L heart failure)

  • Eisenmenger syndrome (R sided failure)

  • Rheumatic heart disease

  • Cardiomyopathy

Cyanosis

• Peripheral cyanosis

  • Cold

  • Unwell

  • Polycythaemia

• Central cyanosis

  • Fall in arterial blood oxygen tension

  • Only recognised if the concentration of reduced Hb in the blood is >5g/dl

    • Harder to recognise in anaemic children

• Check oxygen saturation with pulse oximetry (>94%)

• Cyanosis in a newborn with respiratory distress (RR >60)

  • Cardiac disorders – cyanotic congenital heart disease (tetralogy of Fallot, transposition, Eisenmenger syndrome)

  • Respiratory disorders – surfactant deficiency, meconium aspiration, pulmonary hypoplasia

  • Persistent pulmonary hypertension – vascular resistance fails to fall after birth

  • Infection

  • Metabolic acidosis and shock

• NB; nitrogen washout, if Pa02 is <15kPa likely heart Vs. resp

Left to Right Shunts (Breathless)

• Atrial septal defects

• Ventricular septal defects

• Patent ductus arteriosus

Atrial Septal Defect

• 2 main types

  • Secundum ASD (80%)

    • Defect in the centre of the atrial septum involving the foramen ovale

    • Usually isolated and well tolerated

      • Typically present in 3^rd decade

    • More common in girls

  • Partial / Primum AVSD

    • Affects the endocardial tissue that gives rise to the AV valves

    • Located in the...

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