Jonathan J. Rome

Arterial and venous contributions to near-infrared cerebral oximetry.

BackgroundCerebral oximetry is a noninvasive bedside technology using near-infrared light to monitor cerebral oxygen saturation (Sco2) in an uncertain mixture of arteries, capillaries, and veins. The present study used frequency domain near-infrared spectroscopy to determine the ratio of arterial and venous blood monitored by cerebral oximetry during normoxia, hypoxia, and hypocapnia. MethodsTwenty anesthetized children aged < 8 yr with congenital heart disease of varying arterial oxygen saturation (Sao2) were studied during cardiac catheterization. Sco2, Sao2, and jugular bulb oxygen saturation (Sjo2) were measured by frequency domain near-infrared spectroscopy and blood oximetry at normocapnia room air, normocapnia 100% inspired O2, and hypocapnia room air. ResultsAmong subject conditions, Sao2 ranged from 68% to 100%, Sjo2 from 27% to 96%, and Sco2 from 29% to 92%. Sco2 was significantly related to Sao2 (y = 0.85 × −17, r = 0.47), Sjo2 (y = 0.77 × +13, r = 0.70), and the combination (Sco2 = 0.46 Sao2 + 0.56 Sjo2 − 17, R = 0.71). The arterial and venous contribution to cerebral oximetry was 16 ± 21% and 84 ± 21%, respectively (where Sco2 = &agr; Sao2 + &bgr; Sjo2 with &agr; and &bgr; being arterial and venous contributions). The contribution was similar among conditions but differed significantly among subjects (range, ≈ 40:60 to ≈ 0:100, arterial:venous). ConclusionsCerebral oximetry monitors an arterial/venous ratio of 16:84, similar in normoxia, hypoxia, and hypocapnia. Because of biologic variation in cerebral arterial/venous ratios, use of a fixed ratio is not a good method to validate the technology.

Double-umbrella closure of atrial defects. Initial clinical applications.

Forty patients were catheterized for closure of atrial septal defects with the Rashkind patent ductus arteriosus umbrella device, a modified Rashkind umbrella device, and the newly designed Lock Clamshell Occluder. Patients weighed 8 kg or more (a requirement for transvenous access with the 11F delivery sheath) and had defects suitable for closure based on two-dimensional echocardiography. The new device was at least 1.6 times the diameter of the atrial septal defect as determined by balloon sizing at catheterization. Patients were followed up by telephone, clinical examination, and echocardiography at 6 months. We attempted closure in 34 patients, with atrial septal defects ranging in diameter from 3 to 22 mm; device sizes ranged from 17 to 33 mm. Initial device position immediately after release was correct in all patients. A cerebral embolus occurred in one elderly patient before device placement--the patient died 1 week later. Two instances of early device embolization occurred, and devices were retrieved by catheter without complication. Follow-up of 31 patients discharged with devices in place, for a total of 31 patient-years, has yielded no umbrella-related complications. Adequate imaging studies in 19 patients 6.5 months after device placement revealed no atrial shunt in 12; residual flow through separate, previously unrecognized atrial septal defects occurred in two; and small residual leaks (less than 3 mm) around devices were present in five patients. This initial success indicates that double-umbrella closure of atrial septal defects will aid in the treatment of intracardiac defects.

Transcatheter closure of coronary artery fistulas.

Transcatheter closure of a coronary artery fistula was undertaken in nine patients. There were three fistulas from the left circumflex coronary artery to the coronary sinus, three from the left anterior descending coronary artery to the right ventricular apex, two from the right coronary artery to the superior vena cava/right atrial junction and one fistula from the left circumflex artery to the pulmonary artery. The fistula was closed with Gianturco coils in six patients, a double-umbrella device in two and a combination of an umbrella and coils in one patient. All fistulas are completely occluded. Complications consisted of migration of two coils, one of which was retrieved, and a transient junctional tachycardia in one patient. In an additional three patients with multiple coronary artery fistulas, transcatheter occlusion was not attempted.

Preoperative Brain Injury in Transposition of the Great Arteries Is Associated With Oxygenation and Time to Surgery, Not Balloon Atrial Septostomy

Background— Preoperative brain injury is an increasingly recognized phenomenon in neonates with complex congenital heart disease. Recently, reports have been published that associate preoperative brain injury in neonates with transposition of the great arteries with the performance of balloon atrial septostomy (BAS), a procedure that improves systemic oxygenation preoperatively. It is unclear whether BAS is the cause of brain injury or is a confounder, because neonates who require BAS are typically more hypoxemic. We sought to determine the relationship between preoperative brain injury in neonates with transposition of the great arteries and the performance of BAS. We hypothesized that brain injury results from hypoxic injury, not from the BAS itself. Methods and Results— Infants with transposition of the great arteries (n=26) were retrospectively included from a larger cohort of infants with congenital heart disease who underwent preoperative brain MRI as part of 2 separate prospective studies. Data collected included all preoperative pulse oximetry recordings, all values from preoperative arterial blood gas measurements, and BAS procedure data. MRI scans were performed on the day of surgery, before the surgical repair. Of the 26 neonates, 14 underwent BAS. No stroke was seen in the entire cohort, whereas 10 (38%) of 26 patients were found to have hypoxic brain injury in the form of periventricular leukomalacia. Periventricular leukomalacia was not associated with BAS; however, neonates with periventricular leukomalacia had lower preoperative oxygenation (P=0.026) and a longer time to surgery (P=0.028) than those without periventricular leukomalacia. Conclusions— Preoperative brain injury in neonates with transposition of the great arteries is associated with hypoxemia and longer time to surgery. We found no association between BAS and brain injury.

Anatomic barriers influence the distribution of in vivo gene transfer into the arterial wall. Modeling with microscopic tracer particles and verification with a recombinant adenoviral vector.

We evaluated the extent to which anatomic barriers to vector penetration might influence the distribution of successful in vivo gene transfer into the normal arterial wall. A double-balloon catheter technique with infusion pressures of 100 to 400 mm Hg was used to infuse microscopic tracer particles of the size range of liposomes and viral vectors into normal elastic arteries of sheep. Localization of the tracer particles in tissue sections by light, fluorescence, and electron microscopy suggested that vector-sized particles were delivered to the intima by direct infusion and to the adventitia via the arterial vasa vasorum. Particles were virtually absent from the arterial media. To test the predictions made from the particle studies, we repeated the infusion protocol with high-titer adenoviral vectors. Gene transfer occurred at high levels in the intima and along the adventitial vasa vasorum but again was virtually absent within the media. The ability of medial smooth muscle cells to be transduced was established in separate experiments with a high-pressure (5 atm) porous balloon infusion catheter. We conclude that (1) the anatomy of the normal elastic arterial wall imposes significant limitations on the penetration of particles in the size range of most gene-transfer vectors and (2) the distribution of in vivo gene transfer with adenoviral vectors is correctly predicted by the distribution of inert tracer particles. These findings have important implications for the design of arterial gene-transfer and gene-therapy protocols.

Comparison of surgical, stent, and balloon angioplasty treatment of native coarctation of the aorta: an observational study by the CCISC (Congenital Cardiovascular Interventional Study Consortium).

OBJECTIVES The purpose of this study was to compare the safety and efficacy of surgical, stent, and balloon angioplasty (BA) treatment of native coarctation acutely and at follow-up. BACKGROUND Controversy surrounds the optimal treatment for native coarctation of the aorta. This is the first multicenter study evaluating acute and follow-up outcomes of these 3 treatment options in children weighing >10 kg. METHODS This is a multicenter observational study. Baseline, acute, short-term (3 to 18 months), and intermediate (>18 months) follow-up hemodynamic, imaging data, and complications were recorded. RESULTS Between June 2002 and July 2009, 350 patients from 36 institutions were enrolled: 217 underwent stent, 61 underwent BA, and 72 underwent surgery. All 3 arms showed significant improvement acutely and at follow-up in resting systolic blood pressure and upper to lower extremity systolic blood pressure gradient (ULG). Stent was superior to BA in achieving lower ULG acutely. Surgery and stent were superior to BA at short-term follow-up in achieving lower ULG. Stent patients had shorter hospitalization than surgical patients (2.4 vs. 6.4 days; p < 0.001) and fewer complications than surgical and BA patients (2.3%, 8.1%, and 9.8%; p < 0.001). The BA patients were more likely to encounter aortic wall injury, both acutely and at follow-up (p < 0.001). CONCLUSIONS Stent patients had significantly lower acute complications compared with surgery patients or BA patients, although they were more likely to require a planned reintervention. At short-term and intermediate follow-up, stent and surgical patients achieved superior hemodynamic and integrated aortic arch imaging outcomes compared with BA patients. Because of the nonrandomized nature of this study, these results should be interpreted with caution.

Transcatheter Device Closure of Congenital and Postoperative Residual Ventricular Septal Defects

Background—Our purpose was to describe a 13-year experience with patients undergoing transcatheter device closure of unrepaired congenital or postoperative residual ventricular septal defects (VSDs). Methods and Results—Since 1989, 170 patients (median age, 3.9 years) have undergone catheterization for closure of 1 or more congenital (n=92) or postoperative (n=78) residual VSDs using successive generations of STARFlex-type devices. Outcomes included echocardiographic assessment of residual flow and device position, assessment of VSD shunt/severity, and adverse events. Among 168 patients in whom device implantation was performed, between 1 and 7 devices were placed per patient (median, 1), with multiple devices placed in 40%. There was a significant decrease in left-to-right shunting after device implantation (P<0.001) and significant improvement in VSD size/severity, and device position proved stable. Of 332 adverse events, 39 were related to the device and 261 were related to the catheterization; all but 5 occurred in the periprocedural period. At a median follow-up of 24 months (0 to 154 months), 14 patients had died and 18 had device(s) explanted. Conclusions—Congenital and postoperative VSD closure using STARFlex-type devices resulted in stable improvement in clinical status and decreased interventricular shunting. Although periprocedural events occurred frequently, late events caused by the device were rare. Transcatheter device closure is an effective management option for patients with complex muscular VSDs that are difficult to approach surgically and for postoperative residual VSDs.

Transcatheter closure of atrial septal defects

Recent experience with the spring-loaded patent ductus arteriosus (PDA) occluder has demonstrated several advantages of this device in the closure of intracardiac defects compared with previously described techniques. Pathologic and animal model studies were performed to identify which atrial septal defects (ASDs) might be suitable for device closure and to test a new septal closure double umbrella. Fifty specimens from the Cardiac Registry with unrepaired ASD secunda (20) were analyzed. Mean ASD size was 8x 10 mm (range, 3 x4 to 30x30 mm); 80% (n =40) of ASDs were judged closable with the new device. ASD closure was attempted in four lambs with the Rashkind (hooked single umbrella) ASD occluder. One of four umbrellas

Tetralogy of Fallot with pulmonary atresia. Rehabilitation of diminutive pulmonary arteries.

BackgroundPatients with tetralogy of Fallot, pulmonary atresia, and diminutive pulmonary arteries are a high-risk group for whom there is no consensus on the correct approach to medical management. The purpose of this report is to review a 14-year experience in the treatment of these patients comparing management schemes. Methods and ResultsBetween January 1978 and August 1988, 91 patients with tetralogy of Fallot and pulmonary atresia had an adequate evaluation of their pulmonary artery anatomy before any surgical management. Forty-eight of these patients had diminutive pulmonary arteries (38 to 104 mm2/m2) supplied by aortopulmonary collaterals and were managed in four different fashions. Of the 9 patients repaired primarily, 7 died early and the two survivors had poor hemodynamic outcome. Of the 9 patients conservatively managed with no intervention before 5 years of age, 4 died and only 1 had a satisfactory hemodynamic result after repair. Of 10 shunted patients, 3 died and 3 had satisfactory repairs. Since 1984, we have rehabilitated pulmonary arteries with (1) right ventricle to pulmonary artery surgical graft, (2) balloon dilation of residual pulmonary artery stenoses and embolization of collaterals, and (3) surgical closure of ventricular septal defect and repair of remaining obstructions. Of 20 patients so managed, 7 died after various stages, but 10 of 20 had complete repairs. All repaired patients with subsystemic right ventricular pressures had at least one successful pulmonary artery dilation. ConclusionsA combined catheter-surgery approach begun at an early age in patients with tetralogy of Fallot and pulmonary atresia with diminutive pulmonary arteries appears to enhance the chances of satisfactory complete repair.

Melody Valve Implant Within Failed Bioprosthetic Valves in the Pulmonary Position A Multicenter Experience

Background—Transcatheter pulmonary valve implantation using the Melody valve has emerged as an important therapy for the treatment of postoperative right ventricular outflow tract dysfunction. Melody-in-bioprosthetic valves (BPV) is currently considered an off-label indication. We review the combined experience with transcatheter pulmonary valve implantation within BPVs from 8 centers in the United States and discuss technical aspects of the Melody-in-BPV procedure. Methods and Results—A total of 104 patients underwent Melody-in-BPV in the pulmonary position at 8 US centers from April 2007 to January 2012. Ten different types of BPVs were intervened on, with Melody valve implantation at the intended site in all patients. Following Melody valve implant, the peak right ventricle-to-pulmonary artery gradient decreased from 38.7±16.3 to 10.9±6.7 mm Hg (P<0.001), and the right ventricular systolic pressure fell from 71.6±21.7 to 46.7±15.9 mm Hg (P<0.001). There was no serious procedural morbidity, and no deaths related to the catheterization or implant. At a median follow-up of 12 months (1–46 months), no patients had more than mild regurgitation, and 4 had a mean right ventricular outflow tract gradient ≥30 mm Hg. During follow-up, there were 2 stent fractures, 3 cases of endocarditis (2 managed with surgical explant), and 2 deaths that were unrelated to the Melody valve. Conclusions—Transcatheter pulmonary valve implantation using the Melody valve within BPVs can be accomplished with a high rate of success, low procedure-related morbidity and mortality, and excellent short-term results. The findings of this preliminary multicenter experience suggest that the Melody valve is an effective transcatheter treatment option for failed BPVs.