Extracorporeal membrane oxygenation for cardiac disease: no longer a mistaken diagnosis

Numerical Study of the Effect of the Port Angle of the Superior Vena Cava Supplying Cannula on Hemodynamics in the Right Atrium in VV-ECMO

Objective: To elucidate the pattern of the influence of the port angle of the superior vena cava supplying cannula (SVCS) on hemodynamics within the right atrium in VV-ECMO. Methods: A three-dimensional model of the right atrium was established based on CT images of a real patient. The 3D models of the SVCS and inferior vena cava draining cannula (IVCD) were established based on the Edwards 18Fr and Medos 22Fr real intubation models, respectively. Based on these models, three-dimensional models of the SVCS ports with bending angles of -90°, -60°, -30°, 0°, 30°, 60°, and 90° in the plane formed by the centerline of the SVCS and the center point of the tricuspid valve (TV) were established. Transient-state computational fluid dynamics (CFD) was performed to clarify the right atrium blood flow pattern and hemodynamic states at different SVCS port orientation angles. The velocity clouds, wall pressure, wall shear stress (WSS), relative residence time (RRT), and recirculation fraction (RF) were calculated to assess hemodynamic changes in the right atrium at different angles of the port of the SVCS. Results: As the angle of the port of the superior chamber cannula changed, the location of the high-velocity blood impingement from the SVCS changed, and the pattern of blood flow within the right atrium was dramatically altered. The results for the maximum right atrial wall pressure were 13,472 pa, 13,424 pa, 10,915 pa, 7680.2 pa, 5890.3 pa, 5597.6 pa, and 7883.5 pa (-90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°), and the results for the mean right atrial wall pressure were 6788.9 pa, 8615.1 pa, 8684.9 pa, 6717.2 pa, 5429.2 pa, 5455.6 pa, and 7117.8 pa ( -90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°). The results of the maximum right atrial wall WSS in the seven cases were 63.572 pa, 55.839 pa, 31.705 pa, 39.531 pa, 40.11 pa, 28.474 pa, and 35.424 (-90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°), respectively, and the results of the mean right atrial wall WSS results were 3.8589 pa, 3.6706 pa, 3.3013 pa, 3.2487 pa, 2.3995 pa, 1.3304 pa, and 2.0747 pa (-90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°), respectively. The results for the area percentage of high RRT in the seven cases were 3.44%, 2.23%, 4.24%, 1.83%, 3.69%, 7.73%, and 3.68% (-90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°), and the results for the RF were 21.57%, 23.24%, 19.78%, 12.57%, 10.24%, 5.07%, and 8.05% (-90° vs. -60° vs. -30° vs. 0° vs. 30° vs. 60° vs. 90°). Conclusions: The more the port of the SVCS is oriented toward the TV, the more favorable it is for reducing RF and the impingement of blood flow in the right atrial wall, but there may be an increased risk of RRT. The opposite orientation of the SVCS port to the TV is not conducive to reducing flow impingement on the right atrial wall and RF.

Completion angiography after cardiac surgery for congenital heart disease: complementing the intraoperative imaging modalities

Residual structural pathology after cardiac surgery for congenital heart disease may complicate postoperative recovery. Completion angiograms obtained in the operating room may facilitate early detection and therapy of residual structural abnormalities. Our objective here is to report our institutional experience performing completion angiograms after cardiopulmonary bypass surgery. Between October 2007 and August 2008, 31 patients underwent completion angiograms after 32 cardiac surgical procedures. The median age was 7.5 months (range, 50 days to 31.2 years) and the median weight was 6.5 kg (range, 3.1-153 kg). Type of procedure, angiographic findings, and therapeutic decision were retrospectively reviewed. Procedures (proc) evaluated through completion angiography included comprehensive stage II or Glenn (n = 13), aortic arch reconstruction/conduit (n = 3), repair/palliation of tetralogy of Fallot or pulmonary atresia with ventricular septal defect (n = 4), PVR or conduit replacement (n = 5), and others (n = 7). Unexpected pathology was identified in 18 of 32 (56.3%) proc, which included left pulmonary artery (LPA) stenoses (n = 15), right pulmonary artery (RPA) stenoses (n = 11), and stenosis impairing coronary blood flow (after DKS; n = 1). In 9 of 32 (28.1%) proc, findings may have led to a change in therapeutic management. This included surgical revision (n = 1), 'Hybrid' therapy in the same setting (n = 2: LPA stent, 1; RPA balloon, 1), early catheterization within 3 months (n = 4), and change in medical management (n = 2: change in anticoagulation, 1; early CT, 1). Complications related to completion angiography were seen in only a single procedure (LPA staining). In conclusion, completion angiograms using a dedicated Hybrid cardiac operating suite may aid in early diagnosis and therapy of postsurgical abnormalities. They complement other methods of intraoperative imaging and may reduce the potential need for early surgical or transcatheter reintervention.

Clinical implication of blood levels of B-type natriuretic peptide in pediatric patients on mechanical circulatory support

BACKGROUND

B-type natriuretic peptide (BNP) is a marker of heart failure. In adult patients with heart failure, decreased BNP levels after implantation of ventricular assist devices may be indicative of recovery. However, BNP levels among pediatric patients receiving mechanical support are largely unknown.

METHODS

Fifteen pediatric patients with cardiogenic shock who were supported by extracorporeal membrane oxygenation (ECMO) were evaluated. The BNP levels were determined before ECMO initiation, during ECMO support, and after ECMO removal.

RESULTS

All patients had elevated BNP levels before initiation of ECMO (median, 1,430 pg/mL; range, 361 to 5,000 pg/mL). Among the 15 patients, 1 received heart transplantation. Extracorporeal membrane oxygenation was withdrawn in 2 patients, and the other 12 patients were weaned from ECMO. Four patients died after initially successful weaning from ECMO. The BNP levels of the nonsurvivors (median, 3,685 pg/mL; range, 2,494 to 5,000 pg/mL) were higher than those of the survivors (median, 1,127pg/mL; range, 108 to 3,030 pg/mL) on the next few days after ECMO removal (p = 0.016). The BNP levels on the fourth day after removal of ECMO among the survivors (median, 498 pg/mL; range, 108 to 890 pg/mL) were lower than those among the nonsurvivors (median, 3,900 pg/mL; range, 3,230 to 5,000 pg/mL; p = 0.017).

CONCLUSIONS

Among pediatric patients supported with ECMO, the survivors had lower BNP levels than those who did not survive. We suggest that serial blood BNP levels can be potential markers for monitoring pediatric patients on mechanical circulatory support, and the concept merits further study.

Intra-aortic balloon pumping in children undergoing cardiac surgery: an update of the Liverpool experience

OBJECTIVE

Intra-aortic balloon pumping in children remains a rarity. We report our experience in supporting pediatric cardiac surgical patients with intra-aortic balloon pumping.

METHODS

We reviewed the cases of 24 children supported with intra-aortic balloon pumping after cardiac surgery in our institution from 1994 through 2003.

RESULTS

Mean age at the time of the operation was 5.0 +/- 5.6 years (range, 7 days-17.5 years). Ten patients were infants less than 6 months old. Mean weight was 18.9 +/- 18.1 kg (range, 3.5-58.7 kg). Indications for intra-aortic balloon pump deployment were postoperative hemodynamic deterioration (n = 11, 8 survivors), failure to wean off cardiopu(n = 7, 5 survivors), and prophylaxis before weaning off cardiopulmonary bypass (n = 6, 5 survivors). The balloon was inserted through the ascending aorta in infants and through the femoral artery in children. Eighteen children (7 infants) were weaned off the intra-aortic balloon pump successfully (intra-aortic balloon pump survival, 75%). Mean duration of intra-aortic balloon pump support was 121.3 +/- 140.60 hours (range, 8-670 hours). There were 3 post-intra-aortic balloon pump in-hospital deaths (survival to hospital discharge, 62.5%). Severe intra-aortic balloon pump-related complications were mesenteric ischemia in 1 patient and lower limb ischemia requiring intra-aortic balloon pump removal in 1 patient. At a mean follow-up of 85 +/- 31 months (range, 18-124 months), all 15 long-term survivors were alive and well.

CONCLUSIONS

Use of an intra-aortic balloon pump is an effective modality of cardiac support in properly selected pediatric cardiac surgical patients with refractory low cardiac output. It can be safely used in small infants and neonates. In selected cases with known left ventricular dysfunction, there is a place for prophylactic use of an intra-aortic balloon pump.

Mechanical cardiac support in the young with the Berlin Heart EXCOR pulsatile ventricular assist device: 15 years' experience

The pediatric-size pneumatically driven pulsatile extracorporeal ventricular assist device (VAD) Berlin Heart EXCOR (Berlin Heart Mediprodukt GmbH, Berlin, Germany) was introduced into clinical practice by the German Heart Institute Berlin in 1992. Until July 1, 2005, Berlin Heart EXCOR systems have been used for circulatory support in 68 children up to 18 years of age with severe circulatory failure resistant to pharmacologic therapy. These were patients suffering from cardiomyopathy, fulminant myocarditis, end-stage congenital cardiac defects, and acute heart failure following congenital heart surgery. Mean VAD support time was 35 days (range, 0 to 420 days). Forty-two patients (62%) survived to transplantation or after weaning; 37 patients (54%), including eight infants, were discharged home. These results in patients with very advanced disease have improved significantly in recent years because of technical developments and growing experience in the treatment of patients on the device, in postoperative care and optimal timing for VAD implantation. Timely implantation of the Berlin Heart EXCOR in the course of progressive heart failure now appears to be justified because the system has undergone the necessary modifications and the accumulation of clinical knowledge has made its use highly reliable and safe.

Experience with Extracorporeal Life Support in Pediatric Patients after Cardiac Surgery

Extracorporeal life support (ECLS) had been successfully used in neonatal respiratory failure, but cardiac ECLS has been used increasingly in recent years. The purpose of this study was to review our experience in pediatric patients supported by ECLS for postoperative circulatory failure and to analyze the factors associated with mortality. Between January 1999 and December 2004, 68 pediatric patients (< 18 years old) who received ECLS within 7 days after cardiac surgery at the National Taiwan University Hospital were included in this study. The overall survival rate of this cohort was 32.4%. Age and gender did not affect survival. Patients with separate biventricular physiology had a higher probability of survival than those with systemic-pulmonary shunt or cavopulmonary anastomosis (41.3% vs. 13.6%, p < 0.05). Acute renal failure during ECLS was significantly associated with mortality (83% vs. 33.5%, p < 0.001). After ECLS initiation, the lowest lactate levels on the second to fourth days were lower in survivors than in nonsurvivors (2.4 vs. 3.3 mmol/L, p < 0.05). There was a trend toward a better survival in the most recent 2 years in comparison with the previous 4 years (47.6% vs. 25.5%, p = 0.07), although this trend did not reach statistical significance. In conclusion, nonbiventricular physiology, acute renal failure, and high blood lactate levels after ECLS increased the risk of mortality for pediatric patients requiring ECLS for postoperative cardiac support.