Edward W.K. Peng

Pre-operative sildenafil and pulmonary endothelial-related complications following cardiopulmonary bypass : a randomised trial in children undergoing cardiac surgery*

In a randomised trial, we compared the effects of oral sildenafil (0.5 mg.kg−1) and placebo, administered the day before cardiac surgery, in 24 children. In sildenafil vs placebo patients, pre‐cardiopulmonary bypass median (IQR [range]) cyclic‐guanosine‐monophosphate was not significantly different (29.9 (2.1–208.1 [0.5–391.5]) vs 5.2 (0.3–54.6 [0–628.9]) pmol.ml−1, respectively). Post‐cardiopulmonary bypass, nitrate/nitrite levels were also not significantly different (0.7 (0–8.0 [0–142.8]) vs 0 (0–2.7 [0–52.7]) μM, respectively). Postoperatively, mean (SD) pulmonary vascular resistance (2.64 (2.28) vs 1.90 (1.12) WU.m−2, respectively and oxygenation index (5.29 (4.60) vs 3.38 (2.54), respectively) remained unchanged, whilst oxygen delivery (57.18 (21.24) vs 74.13 (35.46) ml.min−1.m−2, respectively) and bi‐ventricular systolic function (left ventricle 3.78 (0.94) vs 4.55 (1.08) cm.s−1, respectively; p = 0.002; right ventricle 6.93 (1.47) vs 8.09 (2.25) cm.s−1, respectively; p < 0.001) were significantly reduced in the sildenafil group. In this trial, pre‐operative sildenafil did not affect postoperative pulmonary vascular resistance. There was, however, a negative impact on ventricular function and oxygenation.

Tissue Doppler imaging following paediatric cardiac surgery: early patterns of change and relationship to outcome

In this study, tissue Doppler imaging (TDI) was used to assess changes in ventricular function following repair of congenital heart defects. The relationship between TDI indices, myocardial injury and clinical outcome was explored. Forty-five children were studied; 35 with cardiac lesions and 10 controls. TDI was performed preoperatively, on admission to paediatric intensive care unit (PICU) and day 1. Regional myocardial Doppler signals were acquired from the right ventricle (RV), left ventricle (LV) and septum. TDI indices included: peak systolic velocities, isovolumetric velocities (IVV) and isovolumetric acceleration (IVA). Preoperatively, bi-ventricular TDI velocities in the study group were reduced compared with normal controls. Postoperatively, RV velocities were significantly reduced and this persisted to day-1 (PreOp vs. PICU and day-1: 7.7+/-2.2 vs. 3.4+/-1.0, P<0.0001 and 3.55+/-1.29, P<0.0001). LV velocities initially declined but recovered towards baseline by day-1 (PreOp vs. PICU: 5.31+/-1.50 vs. 3.51+/-1.23, P<0.0001). Isovolumetric parameters in all regions were reduced throughout the postoperative period. Troponin-I release correlated with longer X-clamp times (r=0.82, P<0.0001) and reduced RV velocities (r=0.42, P=0.028). Reduced pre- and postoperative LV velocities correlated with longer ventilation (PreOp: r=0.54, P=0.002; PostOp: r=0.42, P=0.026). This study identified reduced postoperative RV velocities correlated with myocardial injury while reduced LV TDI correlated with longer postoperative ventilation.

Synergistic interaction between right ventricular mechanical dyssynchrony and pulmonary regurgitation determines early outcome following tetralogy of Fallot repair

OBJECTIVE The ability of the right ventricle to tolerate acute pulmonary regurgitation (PR) following tetralogy of Fallot (TOF) repair is variable and the mechanisms that underlie this are not completely understood. We hypothesise that dyssynchronous wall mechanics affects the RV tolerance to postoperative PR with adverse effect on early surgical outcome. METHODS Twenty-four TOFs (mean age 19.5+/-15.5 months) undergoing elective repair were prospectively recruited. Ventricular wall mechanics was studied by tissue Doppler echocardiography following induction (preop) and postoperative day one (POD1) and compared with a control group (10 VSD/AVSD). Segmental dyssynchrony, defined as out-of-phase peak myocardial contraction, was determined at the base, mid, apical segments of the septum, RV and LV free walls and scored by the total number of affected segments. PR was graded from absent to severe and RV dimension was quantified by end-diastolic area index (RVEDAI). Cardiac index (CI) was measured by pulse contour cardiac output analysis. Outcome measures were CI, mixed venous oxygen saturation (SvO2), lactate, and duration of ventilation and critical care stay. RESULTS Preoperatively, biventricular free-wall motion was synchronous in both groups. Following surgery, TOF developed RV-septal dyssynchrony (>2 segments in 11 (46%) vs none in control, p=0.01), while the LV free wall remained normal in both groups. RV-septal dyssynchrony correlated with the ventilation time (rho=0.69, p=0.003), critical care stay (rho=0.58, p=0.02) in the presence of PR (n=16), but not with other outcome measures. The relationships between dyssynchrony and early outcome were not seen when PR was absent. In the presence of PR, median RVEDAI was greater with higher dyssynchrony score (>3 segments; p=0.009). The degree of PR did not affect critical care/ventilation time or RVEDAI. The presence of transannular patch (p=0.007) or at least moderate PR (p=0.01) was associated with a more severe dyssynchrony. CONCLUSIONS Dyssynchronous RV-septal wall mechanics occurs early after Fallot repair. The magnitude of dyssynchrony appears to interact synergistically with pulmonary regurgitation to influence RV dimension and early outcome.

Acute B-type natriuretic peptide response and early postoperative right ventricular physiology following tetralogy of Fallot's repair

B-type natriuretic peptide (BNP) response early after a tetralogy of Fallots repair remains unclear. BNP was measured pre- and post-operatively (immediately, day 1) in 18 children undergoing corrective repair with concurrent echocardiography (pre-, post-op day 1) to assess right ventricular (RV) systolic dysfunction, restrictive physiology, wall motion and pulmonary regurgitation (PR). In the first 24 h postoperatively, BNP rose acutely in all patients (mean 34.9 vs 144.4 vs 716.9 pg/ml at pre-op, days 0 and 1; P < 0.001). Immediate postoperative BNP correlated with preoperative haematocrit (rho = 0.52, P = 0.03) and inversely with preoperative oxygen saturation (rho = -0.63, P = 0.007). All patients showed reduced RV systolic function and abnormal wall motion with at least moderate PR in six patients (33.3%) and restrictive physiology in four (24%). Subsequent BNP expression (post-op day 1) correlated with a low RV fractional area change (rho = -0.51, P = 0.04), high oxygen extraction ratio (rho = 0.56, P = 0.02) and high central venous pressure (rho = 0.79, P < 0.001). The LV function and wall motion remained preserved in all patients. The mechanism of BNP expression is likely to be multi-factorial in the presence of a complex postoperative RV physiology in tetralogy of Fallot. An acute BNP response in the early postoperative period reflects an important physiological role and may be used as an adjunct biomarker to assess the RV function.

Myocardial expression of heat shock protein 70i protects early postoperative right ventricular function in cyanotic tetralogy of Fallot

BACKGROUND Right ventricular dysfunction occurs after tetralogy of Fallot repair and may relate to greater myocardial vulnerability to ischemia-reperfusion injury in cyanotic patients. The inducible form of heat shock protein 70 (HSP-70i), a molecular chaperone, is upregulated in response to cellular stress and limits myocardial injury against ischemia-reperfusion. We evaluated the myocardial expression of HSP-70i and its relation to right ventricular function and clinical outcome in patients with tetralogy of Fallot undergoing corrective surgery. METHODS Twenty patients with tetralogy of Fallot were studied: 10 cyanotic (group Cy) and 10 noncyanotic (group noCy). Western blot was used to quantify HSP-70i from resected right ventricular outflow tract myocardium at baseline and subsequent ischemic time. Biventricular function was quantified by tissue Doppler echocardiography and compared with that of 15 age-matched healthy children. Postoperative systemic perfusion was assessed by mixed venous oxygen saturation, oxygen extraction ratio, and lactate. RESULTS Group Cy had thicker septum (median 0.85 vs 0.66 cm; P = .01) and longer crossclamp time (median 100.0 vs 67.5 minutes; P = .004). There were no difference in HSP-70i between groups at baseline (4.12 vs 3.44 relative optical density; P = .45) or subsequent ischemic time. Preoperative biventricular systolic function was reduced in patients with tetralogy compared with controls with further postoperative right ventricular impairment. Group Cy had higher troponin-I levels (median 16.5 vs 11.1 ng/mL; P = .04) and inotrope scores (14.0 vs 6.5; P = .05) but no differences in ventricular function, mixed venous oxygen saturation, oxygen extraction ratio, and lactate between groups. In group Cy, baseline HSP-70i correlated with better postoperative right ventricular function (rho = 0.80; P = .009), mixed venous oxygen saturation (rho = 0.68; P = .04), and oxygen extraction ratio (rho = -0.71; P = .03). These relationships were absent in group noCy. CONCLUSIONS The association of HSP-70i expression with improved right ventricular function and systemic perfusion suggests an important cardioprotective effect of HSP-70i in cyanotic tetralogy of Fallot.

The risk of fatal re-expansion pulmonary oedema in poor left ventricular reserve

Re-expansion pulmonary oedema (REPO) is an uncommon complication which may be encountered following drainage of pneumothorax, pleural effusion or haemopneumothorax. Treatment is usually supportive and some patients may require positive pressure ventilation. We provide a novel description of the mechanism of a fatal REPO in a patient with a small and non-compliant left ventricle (LV). We urge for an extreme caution when performing thoracocentesis in patients with poor LV reserve.

Comprehensive preassessment form for adult cardiac surgery

Comprehensive evaluation of our patients before putting them under “the knife” can never be overemphasized. It is our duty to care for the patients. Detailed history-taking, clinical examination, and investigations are mandatory prior to surgery. For many years, we have striven to make our method thorough and safe for all patients. We propose here a simple, comprehensive preassessment form that is easily applicable in any unit.