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Biomedical subjects

C Mavroudis

Publications and source records attributed to C Mavroudis.

At least 163 records · Page 9Linked to original sources
PubMed1977

A metastasizing ependymoma of the cauda equina. Case report.

A case is described in which a metastatic ependymoma of the cauda equina recurred after prolonged remission. Similarities to five previously reported cases are discussed, with emphasis on the mode of metastasis. Factors most closely associated with distant metastases include early onset, numerous local operations, long survival, and massive local recurrence at the time of distant metastases.

Adult↗
PubMedDate not supplied

Cardiac plasma cell granulomas: response to oral steroid treatment.

Plasma cell granulomas are lesions of uncertain histogenesis arising in a variety of locations, most commonly the lung. Treatment for these lesions is complete surgical excision if possible. Unresectable pulmonary lesions respond to oral corticosteroids and radiation therapy. We report the long-term outcome of two unusual pediatric cases of cardiac plasma cell granulomas originating within the right ventricle and posterior aspect of the left ventricle. The limited literature reports advocate surgical resection for this entity, with no discussion of alternative treatment strategies for unresectable lesions. We prospectively evaluated the response to postoperative oral steroid therapy, as complete surgical excision was not possible in either case. Sequential echocardiography demonstrated additional significant reduction in the size of the masses and the patients remain asymptomatic at 9 and 5.5 years follow-up, without evidence of obstruction or recurrence. Oral corticosteroids should be considered as a treatment option for any unresectable plasma cell granuloma.

Administration, Oral↗
PubMedDate not supplied

Alterations in the natriuretic hormone system related to cardiopulmonary bypass in infants with congestive heart failure.

This study examined changes in the natriuretic hormone system in five infants with congestive heart failure (CHF) due to intracardiac left-to-right shunting who were exposed to cardiopulmonary bypass (CPB) during surgical repair. Plasma concentrations of three hormones [atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and dendroaspis natriuretic peptide (DNP)] and their secondary messenger, guanosine 3',5'-monophosphate (cGMP), were measured, and the biological activity of the system was quantified. At baseline, BNP and DNP concentrations were normal in our patients, a finding that is strikingly different from that of adult CHF patients, whereas ANP concentrations were elevated. Following CPB, ANP concentrations decreased (median, 175 vs 44 pg/ml; p = 0.043) and BNP concentrations increased (median, 25 vs 66 pg/ ml; p = 0.043), whereas DNP concentrations did not change. Following modified ultrafiltration, BNP concentrations increased (p = 0.043), but other natriuretic peptide concentrations did not change. The calculated biological activity of the natriuretic hormone system decreased following CPB [molar ratio, cGMP / (ANP + BNP + DNP); median, 213 vs 127; p = 0.043)]. Additional studies are needed to expand on these findings and identify patients with other types of congenital heart disease who have perioperative disturbances in the natriuretic hormone system and thus might benefit from pharmacologic intervention.

Atrial Natriuretic Factor↗
PubMedDate not supplied

New directions in surgical therapy of arrhythmias.

The success of the radiofrequency catheter ablation procedure for most types of supraventricular and ventricular tachycardia, particularly in young patients, largely eliminated the role of surgical therapy of arrhythmias. However, there remains a subset of arrhythmia patients in whom the catheter approach has not been successful and types of arrhythmias with high recurrence rates following initially successful catheter ablation procedures where surgery can provide more definitive therapy. In addition, the concepts of ablation therapy can be successfully incorporated into the concomitant repair of complex congenital heart disease, resulting in single-stage therapy for structural and rhythm abnormalities. Prospectively, knowledge of the role of anatomic barriers as substrates for future reentrant arrhythmia circuits provides the opportunity to alter these circuits prophylactically at the time of initial surgical repair of congenital heart disease in an attempt to avoid the late development of tachycardia. This article describes our experience during the past decade with 71 patients undergoing arrhythmia surgery using this approach.

Arrhythmias, Cardiac↗
PubMedDate not supplied

Is surgical ligation of an accessory left superior vena cava always safe?

In patients considered for bidirectional Glenn or Fontan procedures, the association of left superior vena cava (LSVC) with ostial atresia of the coronary sinus should be diagnosed preoperatively in order to avoid surgical division or ligation of the LSVC and the negative effect of resulting coronary venous hypertension on myocardial perfusion. This report discusses the angiographic and hemodynamic features of LSVC when it is the only drainage route from a blind coronary sinus. A retrograde flow in the LSVC seen by Doppler ultrasonography should raise the suspicion of this diagnosis.

Angiography↗
PubMedDate not supplied

Testing of an intrathoracic artificial lung in a pig model.

A low input impedance, intrathoracic artificial lung is being developed for use in acute respiratory failure or as a bridge to transplantation. The device uses microporous, hollow fibers in a 0.74 void fraction, 1.83 m2 surface area bundle. The bundle is placed within a thermoformed polyethylene terephthalate glucose modified housing with a gross volume of 800 cm3. The blood inlet and outlet are 18 mm inner diameter vascular grafts. Between the inlet graft and the device is a 1 inch inner diameter, thin-walled, latex tubing compliance chamber. These devices were implanted in Yorkshire pigs via median sternotomy with an end to side anastomosis to the pulmonary artery and left atrium. The distal pulmonary artery was occluded to divert the right ventricular output to the device. Pigs 1 and 2 were supported fully for 24 hrs and then killed. Pig 3 was supported partially for 20 hrs and died from bleeding complications. The first implant, in a 55 kg male pig, transferred an average of 176 ml/min +/- 42.4 of O2 and 190 ml/min +/- 39.7 of CO2 with an average blood flow rate of 2.71/min +/- 0.46. The normalized average right ventricular output power, Pn, was 0.062 W/(L/min) +/- 0.0082, and the average device resistance, R, was 3.5 mmHg/(L/min) +/- 0.62. The second implant, in a 60 kg male pig, transferred an average of 204 ml/min +/- 22.5 of O2 and 242 ml/min +/- 17.2 of CO2 with an average blood flow rate of 3.7 L/min +/- 0.45, Pn of 0.064 W/(L/min) +/- 0.0067, and R of 4.3 mmHg/(L/min) +/- 0.89. The third implant, in an 89 kg male pig, transferred an average of 156 ml/min +/- 39.6 of O2 and 187 ml/min +/- 21.4 of CO2 with an average blood flow rate of 2.5 L/min +/- 0.49, Pn of 0.052 W/(l/min) +/- 0.0067, and R of 3.4 mmHg/(L/min) +/- 0.74. These experiments suggest that such an artificial lung can temporarily support the gas transfer requirements of adult humans without over-loading the right ventricle.

Adult↗
PubMedDate not supplied

New design for a pumping artificial lung.

A new prototype of a pumping artificial lung (PAL) has been designed and tested. The device performs the functions of both the pump and oxygenator components of an extracorporeal perfusion circuit. Previous prototypes that the authors developed (Type A) had gas exchanging microporous fibers formed into propeller-like vanes that, upon rotation, pump the blood. The design of the new PAL prototypes (Type B) uses the rotation of an annular bank of fibers to drive flow. The fiber bank, including sealed gas manifolds, lies within the housing of a modified Bio-Medicus BMP-50 pump head (Bio-Medicus, Eden Prairie, MN). Rotation of the fiber bank is driven through a magnetic coupling. Inlet and outlet gas lines enter the pump head through a sealed bearing. The Type A PAL suffered from insufficient pumping rates and gas exchange, necessitating redesign. The authors have constructed two PAL-B prototypes with a priming volume of only 140 ml and gas exchange surface areas of 0.16 and 0.60 m2. During in vitro saline testing, these prototypes showed significant pump performance, pumping 7.0 L/min against zero head at 3,500 rpm. The larger prototype had exchange rates in saline of up to 71 ml O2/min and 75 ml CO2/min. Gas exchange fluxes (O2 = 119 ml/[min.m2] and CO2 = 125 ml/[min.m2]) for the PAL-B are significantly higher than that of commercially available oxygenators in saline. Future prototypes will have increased surface area and fibers smaller than the 0.038 cm outside diameter fibers used in the present prototypes. A primary concern in using microporous fibers to push the blood was the durability of the fibers at high pump speeds. High speeds exhibited no negative effects on gas exchange abilities or fiber durability.

Artificial Organs↗
PubMedDate not supplied

Ascending aortic extension for right pulmonary artery stenosis associated with ventricular-to-pulmonary artery conduit replacement.

BACKGROUND: Ventricular-to-pulmonary artery conduits in growing patients with congenital heart disease will require replacement from time to time due to somatic growth, neointimal hyperplasia, and pulmonary artery stenosis. The purpose of this article is to review our experience with ascending aortic extension for significant long-segment pulmonary artery stenosis in patients undergoing reoperation for right ventricular-to-pulmonary artery conduit replacement. METHODS: From 1989 to 1997, 8 patients had aortic transection, right pulmonary artery augmentation arterioplasty, and aortic interposition graft (Hemashield in 7 and Gore-tex in 1) in association with right ventricular-to-pulmonary artery conduit replacement in 7 patients and completion Fontan operation in 1 patient. Aortic cross-clamp time was 90 +/- 34 minutes, and the cardiopulmonary bypass time was 205 +/- 37 minutes. RESULTS: All patients survived. In those 7 patients who had conduit replacement, the RV/LV ratio declined from 0.78 +/- 0.15 to 0.45 +/- 0.05 postoperatively (P < 0.05). Average length of stay was 8.9 +/- 7.2 days. Follow-up range is 18 months to 8 years (mean 4 years). Two complications included cardiac transplantation for pre-existing poor left ventricular function and accelerated conduit stenosis leading to conduit re-replacement. CONCLUSION: Ascending aortic extension facilitates long-segment pulmonary artery augmentation arterioplasty and enlarges the retroaortic space, preventing future compression restenosis.

Adolescent↗
PubMedDate not supplied

Complete repair of Tetralogy of Fallot with absent pulmonary valve including the role of airway stenting.

Tetralogy of Fallot (TOF) with absent pulmonary valve (APV) represents an extreme form of tetralogy where pulmonary insufficiency and mild annular stenosis often results in massive pulmonary arterial (PA) dilatation. The aneurysmal left and right PAs often compress the adjacent trachea and bronchi, leading to airway obstruction and respiratory failure in infancy. Between 1991 and 1997, 11 patients underwent a single stage repair of TOF and APV using a valved (10 patients) or nonvalved (1 patient) homograft conduit and PA reduction arterioplasty. There was one (1/11 [9.1%) perioperative and one (9.1%) late death. Both deaths were related to airway complications. Morbidity associated with postoperative respiratory complications and ventilator-dependency due to underlying tracheobronchomalacia is an important problem. Intermediate follow-up shows a high incidence of reintervention for conduit stenosis and/or insufficiency and tracheobronchial compression. These infants also required multiple hospitalizations for recurrent respiratory infections secondary to their tracheobronchomalacia. Stenting of the right and left main bronchi with balloon expandable metallic stents is a new experimental therapy that has been useful in two recent patients with respiratory failure despite satisfactory intracardiac repair. It may provide an attractive alternative therapy to prolonged mechanical ventilation with positive end expiratory pressure in patients with severe tracheobronchomalacia. Complete repair with a valved homograft conduit and reduction pulmonary arterioplasty in infancy at the time of diagnosis is the procedure of choice for infants with TOF with APV. With this approach the patient outcome is essentially determined by their airway status and airway management.

Bronchi↗
PubMedDate not supplied

A comparison of steroid-eluting epicardial versus transvenous pacing leads in children.

OBJECTIVE: To evaluate the acute and chronic performance of steroid-eluting (SE) epicardial (EPI) pacing leads as compared to SE transvenous (TV) pacing leads in children. METHODS: From 1989 through 1997, 55 children with congenital heart disease received a total of 85 SE pacing leads, of which 38 were EPI and 47 TV. The mean age of children receiving EPI leads was younger than those receiving TV leads (7.7 months vs 15.1 years, p = 0.001), and they had shorter follow-up (17.2 months vs 36.2 months, p < 0.001). All leads were evaluated for acute and chronic sensing and capture thresholds, and impedance. RESULTS: Acute and in particular chronic atrial and ventricular sensing and capture thresholds in SE EPI and TV leads were essentially equivalent. [table: see text]. The chronic impedance of TV leads (atrial 525 ohms, ventricular 520 ohms) was consistently higher than EPI leads (atrial 404 ohms, ventricular 386 ohms). CONCLUSION: At intermediate follow-up, SE EPI leads are functionally equivalent to SE TV leads. We recommend the use of SE EPI leads as long as practically feasible prior to using the TV approach in children who will require a life-time of pacing.

Adolescent↗
PubMedDate not supplied

Risk factors for recoarctation and results of reoperation: a 40-year review.

BACKGROUND: We analyzed a single institution 40-year experience with children that had coarctation repair to define risk factors for recoarctation and to evaluate the results of reoperation for recoarctation. MATERIAL AND METHODS: Between 1957 and 1998, 271 patients had primary surgical repair of coarctation of the aorta. Techniques for primary repair included Gore-tex patch aortoplasty (PATCH; n = 118), resection with extended end-to-end anastomosis (RXEEA; n = 69), subclavian flap aortoplasty (SFA; n = 61), resection with simple end-to-end anastomosis (ETE; n = 18), resection and interposition graft (n = 4), and extra-anatomic graft (n = 1). Techniques for recoarctation repair included PATCH, interposition graft, and extra-anatomic graft. RESULTS: Median age at initial repair was 156 days. Major associated cardiac anomalies were present in 96 patients (35%). A hypoplastic aortic arch was present in 37 patients (14%). There were three early deaths (1%) and six late deaths (2%). One patient had paraplegia (0.4%). Recoarctation occurred in 29 patients (11%) and was most frequent with ETE and SFA repairs (33% and 20%, respectively). Multiple logistic regression analysis revealed ETE repair (p = 0.0002), SFA repair (p = 0.049), and aortic arch hypoplasia (p = 0.0001) to be risk factors for recoarctation. Using PATCH as the covariate, the odds ratio to develop recoarctation was 3.5 for SFA, 17.2 for ETE, and 15.2 for hypoplastic aortic arch. There was no mortality or paraplegia after recoarctation repair (n = 23). Six patients had seven balloon angioplasties; two of these patients later required reoperation. Three patients required a second reoperation for persistent coarctation. CONCLUSIONS: In our 40-year review, simple end-to-end anastomosis and subclavian flap repair had the highest incidence of recoarctation, especially when associated with aortic arch hypoplasia. We recommend resection with extended end-to-end anastomosis for repair of neonates and infants and Gore-tex patch aortoplasty for children over the age of 1 year. Surgical repair of recurrent coarctation is safe, effective, and has a low incidence of persistent coarctation.

Anastomosis, Surgical↗
PubMedDate not supplied

Heart transplantation in neonates and in children.

Between May 1988 and July 1991, 28 neonates and children underwent orthotopic heart transplantation at Children's Memorial Hospital in Chicago. Indications for heart transplantation were hypoplastic left heart syndrome (10), dilated cardiomyopathy (13), aortic stenosis with endocardial fibroelastosis (1), complex D-transposition of the great arteries after Senning repair (1), L-transposition of the great arteries with single ventricle after shunt (1), cor biloculare, pulmonary atresia, and situs inversus after Fontan (1), and chronic rejection after heart transplantation for hypoplastic left heart syndrome (1). The age at time of transplantation ranged from 2 days to 17 years (mean, 5.3 +/- 6.1 years). Early deaths were from intraoperative donor right ventricular failure (2) and acute rejection after a second transplant procedure at 21 days (1), for an in-hospital mortality rate of 10.7%. Immunosuppression was with cyclosporine, azathioprine, and prednisone, with an attempt to discontinue the prednisone in neonates at age 6 months as guided by endomyocardial biopsy. Rejection episodes were treated with methylprednisolone pulse (34) or with OKT3 (4). Endomyocardial biopsy (in patients older than 6 months) was used extensively, and acute rejection was diagnosed in 29 of 301 biopsies. Three late deaths occurred (mean follow-up, 16.3 +/- 11.8 months): one of acute rejection at 13 months, one of viral pneumonia at 7 months, and one of intraabdominal sepsis as a complication of peritoneal dialysis at 5 months. Actuarial survival at 2 years is 77% +/- 9% (standard error of the estimate). Heart transplantation for neonates and for children can be performed with acceptable operative mortality. Intermediate results with triple therapy immunosuppression and an intensive rejection surveillance regimen relying on endomyocardial biopsy are encouraging.

Actuarial Analysis↗