Assessing Cardiac Function Gusztav Belteki Rosie Hospital, Cambridge 20/10/2014

Summary of the talk 1.Transitional circulation 2.Ventricular function 3.Cardiac output

Transitional circulation Fetal circulation: - Right ventricular dominance - Fetal shunts Postnatal circulation: - Left ventricular dominance - No shunts (“serially connected” circulation)

Transitional circulation Tricuspid regurgitationOpen ductus arteriosus These are normal findings in the first 72 hours and DO NOT mean PPHN or CHD in a newborn who is not hypoxic !

Ventricular function Stroke volume is determined by: - Preload -Contractility -Afterload Cardiac output = Heart rate X Stroke volume

Ventricular function Left ventricularRight ventricular Systolic = Contractility Diastolic

Left ventricular contractility A useful method of assessing ventricular contractility is visual inspection of the apical four chamber view by a trained eye Quantitative methods: - fractional shortening (FS) - ejection fraction (EF) - velocity of circumferential shortening (Vcf)

M-mode of the left ventricle

Fractional shortening FS = LVEDD - LVESD LVEDD X – 41 % Dependent on contractility AND preload

Poor contractility

FS = LVEDD 3 – LVESD 3 LVEDD 3 X 100 Ejection fraction (EF) (1.2) 3 = Velocity of circumferential fiber shortening Vcf c = LVEDD – LVESD LVEDD X LVET = left ventricular ejection time LVET sqrtRR

Right ventricular dominance SD DS -Dilated right ventricle -Paradoxical septal motion

Right ventricular contractility

Diastolic ventricular function Hypertrophic cardiomyopathy: - Infants of diabetic mothers - Postnatal steroid course - Inborn errors of metabolism Immature myocardium (prematurity)

Hypertrophic obtructive cardiomyopathy

Diastolic ventricular function Normal: E / A > 1 Abnormal: E / A < 0.7 E wave: passive filling A wave: atrial contraction

Cardiac output Cardiac output = Mean arterial pressure Vascular resistance

Cardiac output No shunts: systemic and pulmonary circulations serially connected: Systemic CO = Pulmonary CO Shunts (ASD, VSD, PDA): Systemic CO = Pulm. CO VSD, PDA: Systemic CO = Left ventr. output Pulmonary CO = Right ventr. output

How to measure left ventricular output Aortic stroke distance = aortic root velocity-time integral (VTI) AoSD normal (term newborn) 15 ± 3 cm

How to measure left ventricular output Aortic root diameter (d) Aortic root cross sectional area (AoCSA) AoCSA = (d 2 x π) / 4 (cm 2 )

How to measure left ventricular output Left ventricular output (LVO) = AoSD (cm) x AoCSA (cm 2 ) x HR (bpm) Body weight (ml / min / bwkg) Normal (term newborn): 160 – 320 mL/kg/min BUT: in case of PDA or VSD left ventricular output is not the same as systemic cardiac output !!)

Right ventricular output Right ventricular output (RVO) = PSD (cm) x PCSA (cm 2 ) x HR (bpm) Body weight