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Biomedical subjects

Irving Shen

Publications and source records attributed to Irving Shen.

29 records · Page 2Linked to original sources
PubMed2005

Cardiopulmonary bypass using argatroban as an anticoagulant for a 6.0-kg pediatric patient.

A patient was born with transposition of the great arteries, double-outlet right ventricle, interrupted aortic arch, and a ventricular septal defect and underwent a Damus-Kaye-Stansel procedure with a modified Blalock-Taussig shunt at 14 days old. Three months later, this patient presented with hypoxia and bradycardia was found to have a thrombus present in the main pulmonary artery extending to right pulmonary artery. After initiation of thrombolytic therapy, the patient became severely hypoxic and required the institution of extracorporeal membrane oxygenation. As the result of unknown heparin resistance independent of adequate antithrombin III levels, argatroban therapy was used to achieve desired anticoagulation. The patient was taken to the operating room and converted to conventional cardiopulmonary bypass once adequate activated clotting times were achieved using argatroban. This case report summarizes the use of argatroban as an anticoagulant for a 6.0-kg pediatric patient undergoing cardiopulmonary bypass.

Anticoagulants↗
PubMed2004

Postoperative hypoxemia exacerbates potential brain injury after deep hypothermic circulatory arrest.

BACKGROUND: Deep hypothermic circulatory arrest (DHCA) is often used in infants undergoing the Norwood procedure. These infants are hypoxic after surgery. Previous investigations into the cerebral metabolic response and oxygen utilization after DHCA examined animals with normal arterial oxygenation. This study reports the cerebral metabolic consequences if hypoxemic conditions are present after DHCA. METHODS: Eighteen neonatal piglets were randomly assigned to three groups. The control group was ventilated; the cardiopulmonary bypass group underwent 60 minutes of normothermic cardiopulmonary bypass, and the DHCA group underwent cardiopulmonary bypass and 60 minutes of DHCA (16 degrees to 18 degrees C) followed by rewarming. Hemodynamic and cerebral perfusion data were measured at an arterial partial pressure of oxygen (PaO2) of 150 to 250 mm Hg, and then at moderate hypoxemia (PaO2, 50 to 60 mm Hg) and severe hypoxemia (PaO2, 25 to 35 mm Hg). RESULTS: Cerebral oxygen delivery decreased by 44% from PaO2 150 to 250 mm Hg to severe hypoxemia (p < 0.001). Cerebral oxygen extraction increased from moderate hypoxemia to severe hypoxemia in the control (57.9% +/- 3.7% to 71.8% +/- 3.8%; p = 0.002) and cardiopulmonary bypass groups (61.2% +/- 2.6% to 70.6% +/- 1.2%; p = 0.035); however, the cerebral oxygen extraction of the DHCA group did not increase under these conditions (82.8% +/- 1.8% to 77.9% +/- 4.3%; p = 0.32). The cerebral metabolic rate of oxygen consumption of the DHCA group decreased from PaO2 150 to 250 mm Hg to severe hypoxemia (1.86 +/- 0.20 to 0.99 +/- 0.24 mL O2 x 100 g(-1) x min(-1); p = 0.02), whereas the cerebral metabolic rate of oxygen consumption did not change under these conditions in the control and cardiopulmonary bypass groups. CONCLUSIONS: Under hypoxemic conditions cerebral metabolic rate of oxygen consumption deteriorates after DHCA. Infants exposed to DHCA may be at greater risk of brain injury when postoperative hypoxemia is present. Because maximal cerebral oxygen extraction after DHCA occurs at moderate hypoxemia, techniques that increase cerebral oxygen delivery may reduce the risk of hypoxic brain injury.

Animals↗
PubMed2004

Routine mechanical ventricular assist following the Norwood procedure--improved neurologic outcome and excellent hospital survival.

BACKGROUND: Although excellent survival following the Norwood procedure for palliation of hypoplastic left heart syndrome (HLHS) is being achieved by some, most centers, especially the ones with small surgical volume and limited experience, continue to struggle with initial results. Survivors often showed evidence of significant neurologic injury. The early postoperative care is labor-intensive as attempts are made to balance the systemic and pulmonary circulation for these infants. We report our experience with routine use of mechanical circulatory assist to support the increased cardiac output requirements present following Norwood procedure. METHODS: Eighteen consecutive infants undergoing Norwood operation for HLHS (Oregon Health & Science University [OHSU] 13; University of Louisville [UL] 5) were placed on a ventricular assist device (VAD) immediately following modified ultrafiltration in the operating room using the cardiopulmonary bypass (CPB) cannulas that were in the right atrium and the neoaorta. VAD flows were maintained at approximately 200 mL x kg(-1) x min(-1) and the patients were transported to the intensive care unit (ICU). Patients operated at OHSU also received neurodevelopmental testing before their Glenn procedure, approximately 4 to 6 months following their Norwood operation. RESULTS: All patients were stable on VAD support and no attempt was made to balance the systemic and pulmonary circulation. The ventilator was manipulated to achieve systemic Pa0(2) between 30 and 45 mm Hg and PaC0(2) between 35 and 45 mm Hg. Evidence of hypoperfusion (increasing lactates) was managed by increasing the VAD flow. Lactates normalized [< 2 mmol/L]) by 1.8 +/- 1.1 days following surgery. Average time of VAD support was 3.1 +/- 1.0 (range, 2 to 5 days) and average time until chest closure was 3.4 +/- 1.5 (range, 2 to 8 days). There were two cases of postoperative bleeding (11.1%) requiring reexploration and one case of mediastinitis (5.5%) in a patient who has now gone on to successful Glenn. Sixteen of the eighteen patients survived (hospital survival mean 89% with a 95% confidence interval of 63.9% to 98.1%; 12/13 OHSU [92.3%]; 4/5 UL [80%]). Neurodevelopmental testing using the Mullen Scales of Early Learning and the Vineland Adaptive Behavior Scale were normal for all infants tested. CONCLUSIONS: Routine postoperative use of VAD can support the increased cardiac output demands of infants following Norwood operation and results in a stable postoperative convalescence that does not require aggressive ventilator or inotrope manipulation. Although not a panacea, this strategy can simplify postoperative management, lead to excellent hospital survival, and possibly augment cerebral oxygen delivery, resulting in improved neurologic outcomes for this challenging group of patients.

Cardiac Surgical Procedures↗
PubMed2004

Routine use of mechanical ventricular assist following the Norwood procedure.

Conventional postoperative management after the Norwood procedure in patients with hypoplastic left heart syndrome suffers from three main shortfalls. First, the early postoperative care is often labor-intensive and ironically (despite sometimes heroic efforts), when babies die, health care providers often feel like failures, and in the worst scenarios, surgeons or other physicians create cultures of blame. Second, hospital survival is inconsistent in most centers, especially the ones with small surgical volume and limited experience. Third, survivors often show evidence of significant neurologic impairment. To address these postoperative problems, we have adopted the strategy of routinely placing all our patients with hypoplastic left heart syndrome on mechanical circulatory support immediately after their Norwood procedure. No attempt was made to balance the systemic and pulmonary circulation. Because an oxygenator was not used in the circuit, a much lower level of anticoagulation was used. Once the lactate level normalized, the amount of mechanical circulatory support was weaned. Since January of 2001, 23 patients have been managed using this strategy. The average time of mechanical circulatory support was approximately 3 days and has decreased to 2 days in more recent experience. The overall incidence of complications was 22%, and overall hospital survival was 87%. Neurodevelopmental testing before the Glenn procedure was normal for all patients tested. Routine postoperative use of mechanical ventricular assist device can support the increased cardiac output demands of infants following Norwood procedure and results in a stable postoperative convalescence. This strategy can simplify postoperative management, lead to excellent hospital survival, and possibly augment cerebral oxygen delivery resulting in improved neurologic outcomes for these patients.

Cardiac Output↗
PubMed2004

Heparin-induced thrombocytopenia (HIT) in pediatric cardiac surgery: an emerging cause of morbidity and mortality.

Unfractionated heparin (UFH) is immunogenic, and heparin-dependent antibodies can be demonstrated 5 to 10 days postoperatively in 25% to 50% of adult postcardiac surgery patients. In a minority of these cases (1% to 3% if UFH is continued longer than 1 week) these antibodies strongly activate platelets, causing thrombocytopenia and massive thrombin generation (HIT syndrome). HIT is an intensely procoagulant disorder, and in adult cardiac surgery patients carries both significant thrombotic morbidity (38% to 81%) and mortality (28%). Despite the ubiquitous use of UFH in pediatric intensive care units, and the repeated and sustained exposures to UFH in neonates and young children with congenital heart disease, HIT has been infrequently recognized and reported in this patient population. However, emerging experience at our institution and elsewhere suggests that HIT is significantly under-recognized in pediatric congenital heart disease patients, and may in fact have an incidence and associated thrombotic morbidity and mortality in this patient group comparable to that seen in adult cardiac surgery patients. This article will review HIT in pediatric patients with congenital heart disease and emphasize the special challenges posed in clinical recognition, laboratory diagnosis, and treatment of HIT in this patient group. We will also outline our experience with the off-label use of the direct thrombin inhibitor, argatroban, in pediatric patients with HIT.

Adolescent↗
PubMed2004

Argatroban usage for anticoagulation for ECMO on a post-cardiac patient with heparin-induced thrombocytopenia.

We report a post-Norwood Stage I patient requiring ECMO support using Argatroban as an anticoagulant following diagnosis of heparin-induced thrombocytopenia (HIT). A 2.6 kg female was born with hypoplastic left heart syndrome and underwent a Norwood Stage I operation on day 4 of life. The patient weaned off cardiopulmonary bypass with no complications and was routinely placed on a ventricular assist device (VAD) for 3 days. Heparin was infused at a rate of 16-32 IU/ kg/h to maintain an ACT of 160-180 seconds. Two days after VAD termination, the patient was placed on continuous veno-veno hemofiltration (CVVH). Shortly after CVVH, the patient was diagnosed with HIT and placed on an Argatroban infusion. Five days later, a VAD and subsequent ECMO was used because of decreasing left ventricular function, gross body edema, and poor renal function. This case report summarizes the use of Argatroban during VAD and ECMO support for a patient diagnosed with HIT.

Anticoagulants↗
PubMed2003

Current strategies for optimizing the use of cardiopulmonary bypass in neonates and infants.

The use of cardiopulmonary bypass is still necessary for the repair of many congenital cardiac defects. However, exposure to cardiopulmonary bypass can still lead to major morbidity and sometimes mortality, especially in neonates and infants, despite a perfect surgical repair. Various research-based strategies have been used to minimize some of the complications related to cardiopulmonary bypass, including the systemic inflammatory response, hemodilution, and transfusion requirement. This overview provides some of the strategies that we use in our practice in applying cardiopulmonary bypass in the repair of congenital cardiac defects in neonates and infants.

Aprotinin↗
PubMed2003

Optimizing response of the neonate and infant to cardiopulmonary bypass.

Despite the ability to surgically correct complex defects in neonates and infants, limitations in outcome are sometimes encountered in relation to exposure to cardiopulmonary bypass (CPB). The deleterious effects of CPB in neonates are often pronounced because of their immature tissue/organ function and the disparity between the CPB circuit size and the patient. A variety of techniques that have been developed to prevent or lessen tissue edema, including miniaturization of the circuit and oxygenator, prime additives (eg, albumin, steroids), biocompatible circuitry, and variations in perfusion strategies, are discussed as are post-CPB strategies such as modified ultrafiltration, which removes inflammatory mediator-rich fluid from the patient and bypass circuit. With optimization of the response of the infant to our systems used during repair of their cardiac lesion, we will see significant improvement in surgical outcomes.

Cardiopulmonary Bypass↗
PubMed2002

New technology and methodologies for intraoperative, perioperative, and intraprocedural monitoring of surgical and catheter interventions for congenital heart disease.

We review the new technology and methods available for support of intraoperative and intraprocedural imaging in the catheterization laboratory for surgical and interventional catheterization procedures in the treatment of congenital heart disease. The methods reviewed include miniaturized probes and new ways of using them perioperatively for cardiac imaging from transesophageal, substernal, and intracardiac imaging locations. The smaller and more versatile the probes, the better adapted they will be in providing methods to improve the outcomes in babies born with serious forms of congenital heart disease.

Cardiac Surgical Procedures↗
PubMedDate not supplied

Recurrent pulmonary artery sarcoma.

Pulmonary artery sarcomas are a diagnostic and therapeutic challenge. Most patients are initially thought to have pulmonary emboli, and during embolectomy, a sarcoma is found. Given the significant morbidity and mortality of cardiac sarcomas, an aggressive strategy for resection is indicated, as this leads to benefits in disease-free and overall survival. Imaging tests and clinical signs and symptoms may assist in accurate preoperative determination of pulmonary artery sarcoma. We present an interesting case of a patient with pulmonary artery sarcoma who underwent successful re-resection, along with a brief discussion regarding preoperative imaging and the surgical resection of these tumors.

Aged↗