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Biomedical subjects

M J Reardon

Publications and source records attributed to M J Reardon.

At least 37 records · Page 2Linked to original sources
PubMed1999

Relation of the contractile reserve of hibernating myocardium to myocardial structure in humans.

BACKGROUND: Although dobutamine echocardiography (DE) is widely used to assess myocardial viability in humans, little is known about the relation between contractile reserve and myocardial structure. METHODS AND RESULTS: We evaluated 20 patients with coronary disease (64+/-13 years old, ejection fraction 28+/-7.5%) with DE (up to 40 micrograms . kg(-1). min(-1)), rest-redistribution (201)Tl single photon emission CT, and quantitative angiography before bypass surgery. During surgery, patients underwent transmural myocardial biopsies (n=37) guided by transesophageal echocardiography to determine the extent of interstitial fibrosis and intracellular and interstitial proteins by histopathology and immunohistochemistry. Among the 37 segments biopsied, 16 recovered function as assessed 2 to 3 months later. Segments with postoperative functional recovery had more wall thickening at low-dose DE (28% versus 3%, P<0.001), higher thallium uptake (69% versus 48%, P=0.03), and less interstitial fibrosis (2% versus 28%, P<0.001). Quantitative angiographic parameters did not predict recovery of function. Segments with DE viability (contractile reserve and/or ischemia) had less fibrosis (2.7% versus 28%, P<0.001), less vimentin and fibronectin (both P<0.01), more glycogen (P=0.016), and higher thallium uptake (64% versus 35.5%, P<0.05) than those without viability. Viable segments by both DE and thallium had less fibrosis (1%) than those viable by 1 of the 2 techniques (9%) or not viable by both (28%, P=0.005). Thickening at low-dose DE correlated well with the extent of interstitial fibrosis (r=-0.83, P<0.01). CONCLUSIONS: Contractile reserve during DE correlates inversely with the extent of interstitial fibrosis and the amount of fibronectin and vimentin and directly with rest-redistribution thallium uptake.

Adrenergic beta-Agonists↗
PubMed1999

The anatomical aspects of minimally invasive cardiac valve operations.

Cadaveric dissections were carried out to examine the relationship of the cardiac valve structures to the surface anatomy of the chest as it relates to our approaches to minimally invasive valvular operations. The techniques of upper hemisternotomy and lower hemisternotomy as used at our institution are described.

Cardiac Surgical Procedures↗
PubMed1999

Cardiac autotransplant for surgical treatment of a malignant neoplasm.

Because of their anatomic location, cardiac sarcomas often interfere with cardiac function. Excision is considered to palliate the cardiac defect, but complete excision is often difficult owing to access, particularly in left atrial tumors. Incomplete resection results in tumor recurrence. To achieve complete resection of a large left atrial sarcoma, we used the technique of cardiac explantation, extracorporeal resection of the tumor with cardiac reconstruction, and cardiac autotransplantation.

Adult↗
PubMed1999

Pharmacokinetics of liposomal aerosolized cyclosporine A for pulmonary immunosuppression.

BACKGROUND: The results of pulmonary transplantation are compromised by acute and chronic rejection. We hypothesized that a liposomal form of aerosolized cyclosporine A (CsA) would be selectively deposited and concentrated in the lungs. The theoretical advantage of this therapy is selective pulmonary immunosuppression with prolonged utilization. METHODS: Eighteen dogs were endotracheally intubated; aerosolized liposomal CsA was administered for 15 min. CsA levels were measured in whole blood, lung, trachea, heart, kidney, liver, and spleen at various times after treatment. RESULTS: The lung rapidly absorbs aerosolized liposomal CsA; other organs have much lower concentrations. The retention of pulmonary CsA delivered by liposome aerosol is approximately 120 min in this model. CONCLUSIONS: Aerosolized liposomal CsA is selectively deposited and concentrated in the lungs; other organs absorb less CsA.

Aerosols↗
PubMed1999

Completely laparoscopic resection of a rare pyloric tumor with laparoscopically sutured gastroduodenostomy.

We report the case of a 31-year-old woman who presented with epigastric pain and weight loss. Esophagogastroduodenoscopy revealed a submucosal mass in the distal antrum and pylorus. Endoscopic biopsy of the mass was nondiagnostic. A CT scan confirmed a 3.0-cm mass in the posterior wall of the distal antrum. She underwent laparoscopic resection of the distal antrum and pylorus with end-to-end gastroduodenostomy. Pathologic examination showed an adenomyoma of the antrum and pylorus. Her postoperative course was uncomplicated, and she continues to do well 38 months postoperatively. Gastric adenomyoma is a rare, benign intramural tumor of the antrum and pylorus. Fewer than 40 cases have been described in the literature. The lesions are generally within 4 cm of the pylorus. Histologically, they are characterized by ductal structures lined by cuboidal to columnar epithelium surrounded by smooth muscle bundles and, occasionally, Brunner's-type glands and heterotopic pancreas. Treatment is by resection, and recurrence has not been reported. Laparoscopic resection of portions of the stomach has been reported. Side-to-side gastrojejunostomies (Billroth II) performed laparoscopically have been reported. This is the first report in the English-language literature of a completely laparoscopically performed sutured gastroduodenostomy. Technical details of the procedure and adenomyomas are discussed.

Adenomyoma↗
PubMed1999

Thoracoscopic repair of a recurrent diaphragmatic hernia four years after initial trauma, laparotomy, and repair.

Traumatic diaphragmatic hernia is not an uncommon problem and has been noted after either penetrating or blunt trauma. A high index of suspicion must be maintained in order to identify patients with this injury, as delay in identification may result in significant morbidity and death. It is essential that a thorough evaluation be performed, and if a diaphragmatic hernia is found, surgical repair is necessary. We present a case of thoracoscopic repair of an incarcerated recurrent diaphragmatic hernia appearing several years after successful open (via laparotomy) repair of an acute blunt traumatic hernia. A brief review of the surgical literature is also presented. With the broadening use of minimally invasive surgical techniques, we feel that their application to the repair of chronic diaphragmatic hernia is safe and effective, reduces morbidity, and results in a faster recovery.

Hernia, Diaphragmatic, Traumatic↗
PubMed1999

Thoracoscopic approach to posterior mediastinal neurogenic tumors in the adult.

Although neurogenic tumors are the most frequent posterior mediastinal tumors, few reports exist on thoracoscopic resection, and methods are not yet standardized. Two cases of thoracoscopic resection of benign posterior mediastinal schwannomas are presented. We believe that in carefully selected patients, thoracoscopic resection can be performed easily and with minimal morbidity.

Adult↗
PubMed1999

Stentless xenograft aortic valves.

Replacement of the diseased aortic valve represents one of the triumphs of cardiac surgery; however, the perfect valve substitute continues to elude surgeons after almost four decades of clinical experience. The characteristics of the ideal valve substitute include the following: central flow capacity, low transvalvular gradient, low thrombogenicity, durability, easy availability, resistance to infection, non-immunogenicity, and easy implantability. The pulmonary autograft first performed by Ross (Lancet 1967, 2:956-958) came closest to achieving these goals, but creates a double valve procedure for single valve disease. Aortic valve replacement (AVR) with homograft aortic valve was introduced by Ross in 1962 (Lancet 1962, 2:487) and Barratt-Boyes in 1964 (Thorax 1964, 19:131-150). Like the pulmonary autograft, homograft AVR results in an excellent hemodynamic outcome but suffers from limitations of graft availability, lack of durability, and difficulty with implantation. Mechanical valves and stented tissue valves allow "off the shelf" easy availability as well as easy implantability. These valves are unfortunately intrinsically obstructed to some extent because of the space occupied by the stent and sewing ring. Stent mounted tissue valves also continue to exhibit limited durability. Stentless xenograft aortic valves have been developed as a compromise between these ends of the valve spectrum to allow excellent hemodynamics and hopefully improved durability while allowing "off the shelf" availability in a variety of standard sizes. We examine the rationale for use of the stentless xenograft aortic valve, the clinical development of this valve, and the surgical techniques of implantation.

Animals↗
PubMed1999

Mitral valve replacement with preservation of the subvalvular apparatus.

The introduction of the Starr-Edwards valve allowed complete replacement of diseased left-sided heart valves. With improved cardiopulmonary bypass, myocardial protection, and surgical techniques the mortality rate from aortic valve replacement decreased substantially, whereas the mortality rate from mitral valve replacement remained high, largely because of low cardiac output syndrome. Increasing use of mitral valve repair techniques resulted in a marked decrease in short-term and long-term morbidity and mortality when treating patients with mitral regurgitation. Some believed that this resulted from maintenance of the mitral annular papillary muscle continuity during mitral valve repair. Subsequent experimental and clinical studies have validated the positive short-term and long-term effects of maintaining the integrity of the mitral valve subvalvular apparatus. This article considers the history of the clinical use of preservation of the subvalvular apparatus, the physiologic studies examining this concept, and the clinical data available on its use. It also examines the following: 1) mitral stenosis versus mitral regurgitation and the preservation of the subvalvular apparatus; 2) whether the anterior, posterior, or both areas of the subvalvular apparatus should be preserved; and 3) the surgical techniques for the preservation of the subvalvular apparatus and valve implantation.

Animals↗
PubMed1999

Pheochromocytoma associated with neuroendocrine carcinoma. A new type of composite pheochromocytoma.

The coexistence of pheochromocytoma and other tumor types in a single adrenal gland has been rarely documented. This type of pheochromocytoma is designated "composite" or "mixed," depending on whether the pheochromocytoma and the nonpheochromocytoma components show the same embryologic origin. The nonpheochromocytoma components reported in the composite pheochromocytoma include ganglioneuroma, ganglioneuroblastoma, neuroblastoma, and malignant schwannoma. The components found in the mixed pheochromocytoma include adrenal cortical neoplasms and spindle cell sarcoma. We report a unique case of composite pheochromocytoma in which the nonpheochromocytoma element is a neuroendocrine carcinoma. The histologic and the immunohistochemical profiles of the 2 distinct components of this tumor were typical for those of pheochromocytoma and neuroendocrine carcinoma. This dual differentiation was also supported by ultrastructural findings. This case not only broadens the morphologic spectrum of composite pheochromocytoma but also provides some additional insight into the histogenesis of this rare but fascinating type of tumor.

Adrenal Gland Neoplasms↗
PubMed1999

Mitral valve homograft for mitral valve replacement in acute bacterial endocarditis.

Homograft use for aortic valve replacement (AVR) in aortic valve acute bacterial endocarditis (ABE) has gained in popularity, due mainly to the relative resistance of homografts to infection. Recent success with mitral valve homograft use led us to apply homograft mitral valve replacement (MVR) in a patient with severe ABE that was not amenable to valve repair. Following surgery, the patient improved rapidly with normalization of infection parameters and chest radiography, and was discharged home on postoperative day 11. Follow up echocardiography showed good function of the homograft mitral valve with no regurgitation. After four months, the patient had normal valve function, with no evidence of infection. In conclusion, MVR with a mitral valve homograft in the setting of ABE was satisfactory, though patient follow up was relatively short (four months).

Echocardiography, Transesophageal↗
PubMed1999

Methods of acute postcardiotomy left ventricular assistance.

OBJECTIVE: Despite many technological advances in cardiovascular surgery, some patients still experience postcardiotomy left ventricular (LV) failure that is refractory to both inotropic support and intra-aortic balloon pump (IABP) placement. The primary author (MJR) recently changed from inflow cannulation at the right superior pulmonary vein/left atrial junction to inflow cannulation at the dome of the left atrium. The purpose of this study was to compare data collected during placement of a left ventricular assist device (LVAD) at the junction of the right superior pulmonary vein with positioning the device in the dome of the left atrium. Experimental design, setting, and participants: the medical records of all patients undergoing cardiac surgery by one author (MJR) between 1994 and 1997 were retrospectively reviewed, and 4 patients requiring LVAD placement for short term postcardiotomy support were identified. Each patient's chart was reviewed for duration of LVAD support, average LVAD blood flows, pulmonary capillary wedge pressures (PCWP), preoperative characteristics, postoperative complications, and final outcome for the patients. RESULTS: Accessing the left atrium through the dome resulted in excellent blood flow through the LVAD and allowed for good LV decompression. Hemostasis remained the most common complication regardless of the technique employed; however, the enhanced visibility provided by accessing the left atrium via the dome made repairs less technically difficult. Three patients (75%) were able to be weaned from the LVAD and were discharged from the hospital to home. Two of these patients were cannulated via the left atrial dome making removal of the LVAD easier, thus exposing the patients to less additional operative time. One patient could not be weaned from LVAD support secondary to development of right ventricular failure requiring RVAD insertion and subsequent development of multiple organ failure syndrome. CONCLUSIONS: Patients requiring LV assistance following cardiopulmonary bypass surgery traditionally have high levels of morbidity and mortality. In spite of the complications associated with the placement of an assist device, we remain encouraged by the excellent LV decompression and systemic flows we achieved following implantation of the LVAD through the dome of the left atrium. The superior ease of implantation and decannulation provided better operative care and postoperative management for our patients.

Acute Disease↗
PubMed1999

Technical aspects of implanting the St. Jude Toronto stentless porcine valve.

Stentless xenograft aortic valves were designed to provide superior hemodynamic characteristics and durability, in comparison with stented tissue valves. The senior author (MJR) has implanted 46 St. Jude Toronto stentless porcine valves--with excellent hemodynamic results and no aortic insufficiency--since this valve was released by the Food and Drug Administration in November 1997. Because the implantation technique is significantly different from that of implanting a stented valve, and because proper implantation is critical for proper valve function and avoidance of aortic insufficiency, we discuss our technique in some detail.

Heart Valve Prosthesis Implantation↗
PubMed1998

Operation for acute and chronic aortic dissection: recent outcome with regard to neurologic deficit and early death.

BACKGROUND: We reviewed our experience in the repair of acute and chronic aortic dissection with regard to early neurologic deficit and death. METHODS: Between February 1991 and June 1996, we performed 206 operations on 195 patients for aortic dissection. Ascending or arch repair, or a combination (type A dissection) was performed on 92 of 206 patients (45%); 44 of 92 (48%) were acute dissection and 48 of 92 (52%) were chronic. Descending or thoracoabdominal repair (type B dissection) was performed on 114 of 206 patients (55%); 22 of 114 (19%) were acute and 92 of 114 (81%) were chronic. RESULTS: Among type A cases, strokes occurred in 6 of 92 patients (7%) overall; 4 of 44 (9%) were acute cases and 2 of 48 (4%) were chronic (p < 0.34). Early deaths for type A were 11 of 92 (12%) overall; 9 of 44 (20%) acute and 2 of 48 (4%) chronic (p < 0.02). In type B cases, neurologic complications were 15 of 114 (13%) overall; 7 of 22 (32%) were acute cases and 8 of 92 (9%) were chronic (p < 0.004). Early deaths for type B were 12 of 114 (11%) overall; 3 of 22 (14%) acute and 9 of 92 (10%) chronic (p < 0.6). Preoperative hypotension was significant in acute type A patients, with strokes in 2 of 7 (29%) hypotensives compared with 2 of 37 (5%) normotensives (p < 0.05) and early death in 4 of 7 (57%) hypotensives versus 5 of 37 (14%) normotensives (p < 0.009). CONCLUSIONS: Morbidity and mortality for repair of chronic dissection types A and B were acceptable. Preoperative hypotension in acute type A dissection was a major predisposing factor toward stroke (29% versus 5%, p < 0.05). Acute type B dissection had acceptable mortality (14%) but a high rate of neurologic complications (32%).

Acute Disease↗
PubMed1998

Effect of extended cross-clamp time during thoracoabdominal aortic aneurysm repair.

BACKGROUND: In previous studies of the neurologic outcome of patients undergoing thoracoabdominal aortic aneurysm repair with the simple cross-clamp technique, cross-clamp time of greater than 30 minutes was identified as an important risk factor. We retrospectively examined the effect of clamp time of 30 minutes or greater on outcome for patients undergoing repair with the addition of surgical adjuncts. METHODS: Between February 1991 and June 1996 we operated on 370 patients for thoracoabdominal or descending thoracic aortic aneurysm. Two hundred seventy-one of these patients with cross-clamp times of 30 minutes or greater were included in this study. One hundred twelve patients underwent simple cross-clamp repair, whereas 159 were operated on with the surgical adjuncts of distal aortic perfusion and cerebrospinal fluid drainage. RESULTS: By multivariate analysis, acute dissection, surgical adjuncts, and aneurysm extent proved most significant in overall patient outcome. The overall rate of early neurologic deficits was 23 of 271 (8.5%). For highest risk patients with type II thoracoabdominal aortic aneurysms, the rate of neurologic deficits was 11 of 29 (38%) for cross-clamp versus 6 of 82 (7.3%) for adjunct operation patients (odds ratio = 0.13; p < 0.001). CONCLUSIONS: The adjuncts of cerebrospinal fluid drainage and distal aortic perfusion decreased the risk of extended cross-clamp time during thoracoabdominal aortic aneurysm repair, particularly for highest risk type II.

Aged↗