Patients with vasoplegic syndrome (VPS) in the post-cardiopulmonary bypass setting usually require escalating vasopressor support. The utilization of methylene blue (MB) in the treatment of VPS in the adult population has been well described. We present a 5-year-old girl who developed vasodilatory shock due to VPS that was resistant to escalating doses of adrenergic agonists following cardiac transplantation. After receiving 1 mg/kg of MB, there was a significant improvement in the patient’s mean arterial pressure which allowed for progressive weaning of the vasopressor support. To date, there are limited data regarding the use of MB in pediatric patients with VPS following cardiothoracic surgery. The cellular mechanisms of MB in VPS are discussed and reports of its use in the adult and pediatric population are reviewed. Dosing regimens and potential adverse effects of MB are presented.
Transcatheter mitral valve replacement has been successfully performed with the use of aortic transcatheter heart valves in hundreds of patients worldwide with severe dysfunction of a degenerated mitral bioprosthesis and high surgical risk for repeat operation. The delivery approach in the vast majority of the mitral valve-in-valve procedures has been transapical. Although the transseptal approach may be more technically challenging, it is less invasive and may be preferred by patients. Data from case series and a large international registry suggest that patients treated with transseptal mitral valve-in-valve have faster recovery, more improvement in left ventricular ejection fraction and possibly lower mortality compared with patients treated with transapical approach. A prospective clinical trial, the MITRAL trial (Mitral Implantation of TRAnscatheter vaLves) is evaluating the safety and feasibility of transvenous transseptal mitral valve-in-valve. The experience from this trial has allowed us to improve our procedural approach. In anticipation of a wider adoption of the transseptal approach for mitral valve-in-valve, we describe our current method step-by-step from planning the procedure through postprocedural management. This is an evolving technique that has changed with experience and the transition to newer generation transcatheter heart valve devices. We discuss the use of cardiac computed tomography for planning the procedure including transseptal puncture and valve size selection, provide procedural and technical tips, and discuss postprocedural care.
While surgical repair of tetralogy of Fallot (TOF) is generally associated with good early outcomes, late complications affect long-term survival and may require reoperation. Pulmonary regurgitation (PR) and tricuspid regurgitation (TR) may increase the risk of arrhythmias, reduced cardiac function, and sudden death. Tricuspid valve function can be compromised secondarily in the setting of PR or directly as a result of injury or alteration of the valve related to the original TOF repair. This article reviews the etiologic mechanisms, pathophysiological implications, and surgical interventions for TR. Effective management following TOF repair requires consideration of TR to optimize late outcomes.
Cardiomyopathy (CM) is associated with a significant risk for thrombosis and an increased risk for thromboembolic events. Early studies invoked blood stasis or flow disturbance as the principal underlying mechanisms. More recent evidence has linked CM with a hypercoagulable state, as demonstrated by elevated levels of thrombin-antithrombin complexes, prothrombin fragment F1+2, and fibrinopeptide A, all indices of thrombin activation. Thrombomodulin (TM), an integral membrane protein found on the endocardial endothelium (EE), is a potent thrombin inhibitor via activation of the protein C pathway. We hypothesized that the increased ventricular wall tension characteristic of CM would result in reduced TM protein expression on the surface of EE, which would, in turn, result in an impairment of local activated protein C (APC) activity, thereby increasing the risk for thrombosis. Using a rabbit pacing-induced CM model, we quantified TM protein expression on EE over time by digital immunohistochemical analysis (n = 4/time point), expressed as arbitrary units (AU)/mm of left ventricular (LV) perimeter. Baseline TM staining of LV endocardial segments was 1,669 ± 128 AU/mm. After 8 weeks of rapid pacing, TM protein expression on EE was markedly decreased (175 ± 41 AU/mm, p < .0001 vs control LV). TM protein expression remained significantly low after 15 weeks of pacing compared to control LV (142 ± 32 AU/mm, p < .0001). Western blot analysis confirmed the immunohistochemical pattern of reduced TM protein expression in CM. Persistence of staining for von Willebrand factor, which is stored in intracellular Weibel-Palade bodies, provided evidence that decreased TM staining was not due to endocardial loss. To assess the physiologic consequence of reduced TM expression, we measured in situ formation of APC using a chromogenic assay. Segments of control LV (n = 4) generated 2,100 ± 138 fmol APC/min/cm2. In contrast, LV harvested after 8 and 15 weeks of pacing generated only 329 ± 35 and 307 ± 78 fmol APC/min/cm2, respectively (p < .0001 vs control LV). Conclusion: Endocardial TM protein expression is reduced by 90% at 8 weeks and 92% at 15 weeks following rapid pacing. This decrease in TM results in an 85% reduced capacity of the EE to generate activated protein C compared to normal LV. Reduced TM expression in CM markedly impairs APC formation, thereby contributing to a significant loss of endocardial thromboresistance.
Interrupted aortic arch (IAA) is a rare congenital defect resulting from the loss of luminal continuity between the ascending and descending aorta. Classification is determined by the location of the interruption. Nearly all patients have a ventricular septal defect (VSD) and patent ductus arteriosus. Patients with IAA should be evaluated for microdeletion of chromosome 22q11 and DiGeorge syndrome. Diagnosis may be made by prenatal ultrasound or with postnatal echocardiography. Advanced medical imaging (catheterization, CT) may aid diagnosis and operative planning. Prior to operative repair, ductal patency is maintained with a PGE1 infusion and lower body perfusion is optimized. After resuscitation of the patient, surgical repair with a direct aortic anastomosis and correction of associated cardiac anomalies (VSD) is performed. Following repair of IAA, patients should be monitored for development of late complications of arch obstruction, left ventricular outflow obstruction, and bronchial obstruction.
