M H Scallan | PubMed Health

PubMed1999

Modified ultrafiltration improves global left ventricular systolic function after open-heart surgery in infants and children.

OBJECTIVES: Modified ultrafiltration increases blood pressure and cardiac index following open-heart surgery in children, but it is unclear if this is secondary to an improvement in global left ventricular function. A previous report has suggested that left ventricular systolic function as assessed in a single chord is improved by ultrafiltration (Davies MJ, Nguyen K, Gaynor JW, Elliott MJ. Modified ultrafiltration improves left ventricular systolic function in infants after cardiopulmonary bypass. J Thorac Cardiovasc Surg 1998;115:361--370). The prominent vascular actions of modified ultrafiltration necessitate left ventricular assessment using load-independent indices of systolic and diastolic function. METHODS: In 22 consecutive infants and children undergoing open-heart surgery, left ventricular function was assessed following bypass and then 10 min later. Sixteen children (median weight 8.1 kg) underwent modified ultrafiltration during this period, the remainder (median weight 7.3 kg) were controls for spontaneous recovery without ultrafiltration. Real-time pressure-volume loops, with transient inferior caval vein snaring were generated from conductance and microtip pressure catheters inserted through the LV apex. From these, load-independent (slope of the end-systolic pressure-volume [Ees] and end-diastolic pressure-volume [Eed] relationships) and load-dependent (Pmax, maximum LV pressure; Ped, end-diastolic LV pressure; maximum [dP/dtmax] and minimum [dP/dtmax] time derivatives of LV pressure; tau, time constant of isovolumic relaxation) indices of left ventricular function were measured. RESULTS: Haemoconcentration was achieved in all modified ultrafiltration patients, median increase in haematocrit 34% (interquartile range 21%, 42%), final haematocrit 0.40 (0.35, 0.41). Ees increased 58% (9, 159, P = 0.005). The changes in Eed, Pmax, Ped, dP/dtmax, dP/dtmin, and tau were not significantly different from the control group. CONCLUSION: Modified ultrafiltration improves global left ventricular systolic function in infants and children following open-heart surgery.

Cardiac Surgical Procedures↗

PubMed1998

Left ventricular dysfunction after open repair of simple congenital heart defects in infants and children: quantitation with the use of a conductance catheter immediately after bypass.

OBJECTIVE: Quantification of myocardial injury after the simplest pediatric operations by load-independent indices of left ventricular function, using conductance and Mikro-Tip pressure catheters (Millar Instruments, Inc., Houston, Tex.) inserted through the left ventricular apex. METHODS: Sixteen infants and children with intact ventricular septum undergoing cardiac operations had left ventricular function measured, immediately before and after bypass. Real-time pressure-volume loops were generated by conductance and Mikro-Tip pressure catheters placed in the long-axis via the left ventricular apex, and preload was varied by transient snaring of the inferior vena cava. RESULTS: Good quality pressure-volume loops were generated in 13 patients (atrial septal defects, n = 11; double-chambered right ventricle, n = 1; supravalvular aortic stenosis, n = 1; age 0.25 to 14.4 years, weight 3.1 to 46.4 kg). Their mean bypass time was 41 +/- 14 minutes and mean aortic crossclamp time 27 +/- 11 minutes. End-systolic elastance decreased by 40.7% from 0.34 +/- 0.17 to 0.21 +/- 0.15 mm Hg-1.ml-1.kg-1 (p < 0.001). There were no significant changes in the slope of the stroke work-end-diastolic volume relationship, end-diastolic elastance, time constant of isovolumic relaxation, and normalized values of the maxima and minima of the first derivative of developed left ventricular pressure. CONCLUSION: Load-independent indices of left ventricular function can be derived from left ventricular pressure-volume loops generated by conductance and Mikro-Tip pressure catheters during the perioperative period in infants and children undergoing cardiac operations. Incomplete myocardial protection was demonstrated by a deterioration in systolic function after even short bypass and crossclamp times.

Adolescent↗