Assessment of left-to-right shunt and left ventricular function in isolated ventricular septal defect. Echocardiographic study

Left Ventricular Dysfunction Following Repair of Ventricular Septal Defects in Infants

Left ventricular systolic dysfunction (LVSD) is frequently observed following repair of ventricular septal defects (VSD), although little is known about its incidence, time course, or risk factors. Among infants undergoing VSD repair, for postoperative LVSD, we sought to determine (1) incidence, (2) predictors, and (3) time to resolution. We queried our institution's surgical database for infants who underwent repair of isolated VSDs from November 2001 through January 2019. The primary outcome was postoperative LVSD, which was defined as a shortening fraction (SF) of <26% by M-mode. Postoperative echocardiograms were reviewed, and measurements were made using standard methods. Receiver operating characteristic analysis was generated to determine the preoperative left ventricular internal dimension (LVIDd) z-score most predictive of LVSD. Multivariable analysis was conducted to determine associations with LVSD; covariates in the model were weight percentile, genetic syndrome, preoperative diuretic, VSD type, and preoperative LVIDd z-score. Of the 164 patients who met inclusion criteria, 62 (38%) had postoperative LVSD. Fifty-eight (94%) of patients had resolution of LVSD within 9 months of surgery. Preoperative LVIDd z-score of >3.1 was associated with both an increased incidence of postoperative LVSD and prolonged time to resolution. Multivariable logistic regression analysis showed only preoperative LVIDd z-score was independently associated with postoperative LVSD. LVSD following VSD closure is common, but nearly all cases resolve by 9 months postoperatively. Elevated LVIDd prior to surgery is associated with postoperative LVSD. These data suggest VSD closure should be considered prior to the development of significant left ventricular dilation.

Regional functional depression immediately after ventricular septal defect closure

Left ventricular ejection is depressed immediately after repair of ventricular septal defect (VSD). Postrepair functional depression seen after VSD closure could result from a reduction in preload. However, other mechanisms could be at work. Functional depression could also be caused by closure of a low-impedance path for left ventricular ejection, the introduction of a stiff akinetic patch, or the operation itself. We reasoned that functional depression mediated by changes in preload or afterload should symmetrically affect end-diastole and end-systole, whereas depression resulting from changes in septal mechanics should be localized. We, therefore, performed segmental wall-motion analysis on intraoperative echocardiograms from patients undergoing VSD and atrial septal defect repair. After VSD closure, there was an asymmetric change in left ventricular end-systolic segment length and a decrease in fractional segment shortening localized to the septal and lateral walls, whereas patients with atrial septal defect had a symmetric increase in fractional shortening. These results suggest that acute functional depression after VSD repair is a result of localized impairment of septal function.

Mechanism of decreased forward stroke volume in children and swine with ventricular septal defect and failure to thrive

Children with ventricular septal defect (VSD) often demonstrate failure to thrive (FTT). Such patients usually have reduced systemic cardiac output which has been postulated as a cause for their growth retardation. This study was conducted to ascertain the mechanism of the reduced cardiac output in children with VSD and FTT and also in a porcine model of VSD. Forward stroke volume was reduced in VSD-FTT children, 31 +/- 8 ml/m2, compared to normal children, 49 +/- 15 ml/m2 (P less than 0.05), but was not reduced in children with VSD and normal growth and development (41 +/- 16 ml/m2). Forward stroke volume was also reduced in swine with VSD compared to controls. Contractility assessed by mean velocity of circumferential shortening (Vcf) corrected for afterload was similar in normals and VSD-FTT children. Contractile performance was also similar in normal and VSD swine. Afterload assessed as systolic stress was similar in FTT-VSD children and normal subjects. Preload assessed as end-diastolic stress was increased in the VSD-FTT group. End-diastolic volume was not larger in the VSD-FTT group. We conclude that the reduced stroke volume seen in VSD-FTT children and VSD-swine was not due to reduced contractility, increased afterload or reduced preload. The reduced stroke volume may have been due to failure of end-diastolic volume to increase adequately.

Rest and exercise ventricular function in adults with congenital ventricular septal defects

Rest and exercise right and left ventricular function were compared using equilibrium gated radionuclide angiography in 19 normal sedentary control subjects (mean age 28 years, range 22 to 34) and 34 patients with hemodynamically documented congenital ventricular septal defect (VSD) (mean age 27 years, range 20 to 40). The 34 patients with VSD were divided into 3 groups: those in Group 1 (17 patients) had pulmonary to systemic blood flow ratios of less than 2 to 1; those in Group 2 (12 patients) had prior surgical closure of VSD (mean interval from surgery 17 years, range 9 to 22), and those in Group 3 (5 patients) had Eisenmenger's complex. Gated radionuclide angiography was performed at rest and during each level of graded supine bicycle exercise to fatigue. Heart rate, blood pressure, maximal work load achieved, and right and left ventricular ejection fractions were assessed. The control subjects demonstrated an increase in both the left and right ventricular ejection fractions with exercise (0.70 +/- 0.07 to 0.79 +/- 0.05 and 0.46 +/- 0.06 to 0.57 +/- 0.04; p less than 0.001 for left and right ventricles, respectively). All study groups failed to demonstrate an increase in ejection fraction in either ventricle with exercise. Furthermore, resting left ventricular ejection fraction in Groups 2 and 3 was lower than that in the control subjects (0.59 +/- 0.09 and 0.54 +/- 0.06 versus 0.70 +/- 0.07; p less than 0.001) and resting right ventricular ejection fraction was lower in Group 3 versus control subjects (0.30 +/- 0.07 versus 0.46 +/- 0.06; p less than 0.001). Thus (1) left and right ventricular function on exercise were abnormal in patients with residual VSD as compared with control subjects; (2) rest and exercise left ventricular ejection fractions remained abnormal despite surgical closure of VSD in the remote past; (3) resting left and right ventricular function was abnormal in patients with Eisenmenger's complex; (4) lifelong volume overload may be detrimental to myocardial function.