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Biomedical subjects

Thomas M Beaver

Publications and source records attributed to Thomas M Beaver.

13 recordsLinked to original sources
PubMed2007

Effect of sildenafil on pulmonary artery pressure, systemic pressure, and nitric oxide utilization in patients with left ventricular assist devices.

BACKGROUND: Pulmonary artery hypertension can complicate the early postoperative care of patients with left ventricular assist devices (LVADs). Inhaled nitric oxide (INO) is frequently used to manipulate pulmonary resistance after LVADs have been placed. We evaluated the effect of oral sildenafil therapy on pulmonary artery pressure, systemic pressure, and nitric oxide utilization. METHODS: After Institutional Review Board approval, the records of 10 consecutive adult patients with LVADs and pulmonary hypertension who received sildenafil were reviewed. Demographics, surgical history, INO use, inotrope requirements, and hemodynamic response to oral sildenafil at multiple intervals were collected. Hemodynamic data were analyzed with a two-way analysis of variance of repeated measures with correction for multiple comparisons. RESULTS: There were 8 men and 2 women with 6 Heartmate XVE LVADs and 4 Thoratec LVADs (both, Thoratec, Pleasanton, California). When weaning was attempted, 8 patients who received INO demonstrated rebound pulmonary hypertension or increased right heart dysfunction. All patients were on inotropic therapy with dobutamine and milrinone. Sildenafil produced a significant reduction in pulmonary artery systolic pressure within 90 minutes of oral administration (p = 0.042). Significant changes in systolic blood pressure, mean arterial pressure, systemic vascular resistance, and heart rate were not observed. All 8 patients receiving INO were weaned within 12 hours without recurrent pulmonary hypertension. All 10 patients were weaned from inotropic support within 72 hours. No patient suffered right-side heart failure requiring intervention. CONCLUSIONS: Oral sildenafil represents a useful adjunctive therapy for patients with LVADs. In our series, it provided additional reduction of pulmonary artery pressure, and facilitated weaning from INO and inotropes without deleterious hemodynamic consequences.

Administration, Inhalation↗
PubMed2007

Perioperative differences between endovascular repair of thoracic and abdominal aortic diseases.

BACKGROUND: With the US Food and Drug Administration approval of the TAG thoracic device, more thoracic pathologies are being treated using endovascular techniques. Although endovascular abdominal and thoracic aortic repairs have some apparent similarities, there are substantive anatomic, pathologic, and technical differences that could impact perioperative outcomes. The purpose of this study is to identify these differences. METHODS: During a 5-year period, 121 endovascular thoracic aortic repairs (TEVAR) and 450 abdominal aortic repairs (EVAR) were performed at a single institution. Preoperative, intraoperative, and early postoperative data were prospectively collected and retrospectively reviewed. Aggregate outcome measures were compared between the two cohorts, with statistical significance achieved at P < .05. RESULTS: The mean age of patients undergoing EVAR was 72.8 +/- 8.3 compared with 68.3 +/- 13.9 for TEVAR (P = .02). More women underwent TEVAR (30.6% vs 11.1%, P < .001). Aneurysms undergoing TEVAR were larger than those for EVAR (62.0 mm vs 58.3 mm, P = .01). Intraoperatively, EVAR required 26.2 minutes of fluoroscopy compared with 22.1 minutes for TEVAR (P < .001). The amount of contrast used was higher in TEVAR (133.6 mL vs 93.6 mL, P < .001). The mean procedure times were 164 minutes for EVAR and 115 minutes for TEVAR (P < .001). Iliac conduits were required in 46 patients (10.2%) undergoing EVAR, and in 24 (19.8%) undergoing TEVAR (P = .007). The 30-day or in-hospital mortality was 2.0% for EVAR and 5.0% for TEVAR (P = NS). The median length of stay was longer for TEVAR (3 days vs 2 days, P =.034). There were 54 postoperative complications in 36 TEVAR patients (29.8%), including 13 neurologic (10.7%), 8 renal (6.6%), 7 pulmonary (5.8%), 6 ischemic (5.0), and 5 (4.1%) hemorrhagic events. Among the EVAR group, 136 (30.2%) patients had postoperative complications, which included 45 ischemic (10.0%), 34 wound (7.6%), 22 renal (4.9%), 12 cardiac (2.7%), 8 pulmonary (1.8%), 5 gastrointestinal (1.1%), and 4 neurologic (0.9%) events. CONCLUSIONS: A relatively higher proportion of women underwent TEVAR than EVAR, and this was reflected in the greater need for iliac conduits to accommodate the larger delivery catheters of the thoracic devices. Intraoperative imaging techniques were also different, and TEVAR required higher contrast volumes despite shorter overall procedure times. The incidence of strokes and spinal cord ischemia was also higher during TEVAR. Despite apparent similarities of devices and techniques, EVAR and TEVAR are fundamentally different procedures with different perioperative outcomes.

Adult↗
PubMed2006

Effectiveness of nesiritide on dialysis or all-cause mortality in patients undergoing cardiothoracic surgery.

BACKGROUND: Natriuretic peptides have been shown to have favorable renal effects. However, recent evidence suggests potential renal side effects in patients with congestive heart failure. HYPOTHESIS: This study examined the effect of nesiritide (human B-type natriuretic peptide) on hemodialysis or death in patients undergoing cardiothoracic surgery. METHODS: This retrospective cohort study included patients (n = 940) undergoing nontransplant adult cardiothoracic surgery between July 2001 and February 2004. Patients receiving nesiritide within 3 days after and not before surgery (n = 151) were compared with those not given nesiritide (n = 789) for incidence of hemodialysis or in-hospital death by Day 21 (HD/death). Patients with preexisting dialysis and intraoperative deaths were excluded. Forward inclusion multiple logistic regression was used based on published risk factors for HD/death. RESULTS: Of 940 patients (318 coronary artery bypass graft, 348 valve, and 274 thoracic aorta), 36 required dialysis and 60 patients died (HD/death; n = 77). Adjusted for significant confounders (gender, age, procedure, intra-aortic balloon, baseline serum creatinine mg/dl [SCr], 1 day % SCr increase), nesiritide showed a statistically nonsignificant HD/death reduction (odds ratio [OR], 0.58; 95% confidence interval [CI], 0.29-1.17; p = 0.129) in the group as a whole. When stratified by baseline SCr, a significant benefit was noted in patients with SCr > 1.0 (OR, 0.35; 95% CI 0.14-0.87; p = 0.024), while no significant effect was found in patients with SCr < 1.0 (OR, 1.55; 95% CI 0.48-5.07, p = 0.465). CONCLUSIONS: Nesiritide appears promising in reducing the risk of dialysis or death in patients with SCr > 1.0 undergoing cardiothoracic surgery; however, no effect was noted with SCr < 1.0. This study provides strong rationale for a randomized trial.

Acute Kidney Injury↗
PubMed2006

Cytokine profile after lung transplantation: correlation with allograft injury.

BACKGROUND: Post-lung transplant reperfusion edema (PLTRE) and its more severe form, primary graft failure (PGF), occur in 10% to 60% of lung transplant recipients. We hypothesized that PLTRE and PGF would be associated with an elevated proinflammatory cascade and that the allograft would be the source of cytokine appearance in the circulation. METHODS: Pulmonary arterial and systemic arterial samples were obtained at baseline and at 4, 8, and 24 hours after reperfusion. Post-lung transplant reperfusion-edema and PGF were defined as PaO2/FiO2 less than 300 with a mild or moderate infiltrate, or less than 200 with a severe infiltrate and ventilator dependence after 72 hours, respectively. Tumor necrosis factor alpha (TNFalpha), interleukin (IL)-6, IL-8, and IL-10 concentrations were determined by immunoassay. RESULTS: Fifteen single and 6 bilateral lung recipients were studied. Six (29%) had PLTRE and 4 (19%) had PGF; these patients had an overall elevation in plasma IL-6, IL-8, and IL-10 concentrations (all p < 0.05). Subgroup analysis revealed a significantly greater elevation in IL-6, IL-8, and IL-10 levels in PGF patients (all p < 0.01) versus PLTRE. In the PGF group, TNFalpha and IL-10 concentrations were significantly greater in the systemic versus the pulmonary arterial samples (p < 0.05). CONCLUSIONS: Patients with PLTRE and PGF exhibited graded increases in IL-6, IL-8, and IL-10 concentrations. The PGF patients had higher TNFalpha and IL-10 systemic arterial concentrations overall, consistent with the allograft being a source of this cytokine production.

Adult↗
PubMed2006

Using recurrence quantification analysis determinism for noise removal in cardiac optical mapping.

Selecting signal processing parameters in optical imaging by utilizing the change in Determinism, a measure introduced in Recurrence Quantification Analysis, provides a novel method using the change in residual noise Determinism for improving noise quantification and removal across signals exhibiting disparate underlying tissue pathologies. The method illustrates an improved process for selecting filtering parameters and how using measured signal-to-noise ratio alone can lead to improper parameter selection.

Algorithms↗
PubMed2005

Oral sildenafil reduces pulmonary hypertension after cardiac surgery.

BACKGROUND: Treatment of postoperative pulmonary hypertension with intravenous (IV) pulmonary vasodilators is hampered by the lack of selectivity. Inhaled nitric oxide produces selective pulmonary vasodilation; however, it requires a special device, and weaning can cause rebound. Oral sildenafil is a phosphodiesterase type V inhibitor. Sildenafil can produce sustained pulmonary vasodilatation in patients with hypoxic or primary pulmonary hypertension; however, experience with postoperative pulmonary hypertension is limited. We report our initial experience with eight patients who received oral sildenafil as adjunctive therapy for postoperative pulmonary hypertension METHODS: We reviewed the charts of eight adult patients with postoperative pulmonary hypertension who received oral sildenafil (25 to 50 mg) to facilitate weaning of IV (milrinone, nitroglycerine, and sodium nitroprusside) and inhaled (nitric oxide) pulmonary vasodilators. Hemodynamic data were recorded before and 30 and 60 minutes after the initial dose of sildenafil. RESULTS: After the initial dose of sildenafil, mean pulmonary artery pressure was reduced by 20% and 22% at 30 and 60 minutes, respectively (p < 0.05). Pulmonary vascular resistance index decreased by 49% and 44% at 30 and 60 minutes, respectively (p < 0.05). Sildenafil had no clinically significant effects on cardiac index, mean arterial pressure, or systemic vascular resistance. Subsequent doses of sildenafil were administered at regular intervals, allowing successful weaning of concomitant pulmonary vasodilators. CONCLUSIONS: Oral sildenafil is an effective agent for treatment of postoperative pulmonary hypertension and can be used to facilitate weaning of inhaled and IV pulmonary vasodilators.

Adult↗
PubMed2005

Transferring diagnosis versus actual diagnosis at a center for thoracic aortic disease.

BACKGROUND: Lack of physician awareness of thoracic aortic disease has received increased media attention. As a referral center for thoracic aortic disease our institutional experience confirms discrepancies between the transferring diagnosis and the actual pathologic diagnosis. A retrospective review was undertaken to identify the incidence and sources for disparate diagnoses. METHODS: Medical records from 100 consecutive patients transferred to The University of Florida--Shands Hospital between April 2002 and October 2003 were reviewed. To identify sources for error, the charts of 24 patients with diagnostic discrepancies were examined in detail with attention to outside radiologic reports, level of physician experience, and additional diagnostic testing required. RESULTS: The transferring diagnosis of 24 patients was different from the final aortic pathologic disease. The most common discrepancies were misclassifications of dissections and aneurysms. Seven patients had either no leak or no dissection. Two patients had misleading "pulsation artifacts" on their computed tomographic scans. In half of the patients diagnostic differences were secondary to initial misinterpretation by the referring radiologist. Seventeen of 24 patients underwent additional diagnostic testing. Misdiagnoses were more common when the referring physician was not a surgeon (15 of 24). The diagnosis of 5 patients was confirmed only in the operating room. CONCLUSIONS: A significant incidence of disparate diagnosis was identified between transferring facilities and our referral center. Discrepancies were secondary to initial radiographic misinterpretation and the complexity of thoracic aortic pathologic disease. Medical schools and continuing medical education programs should place increased emphasis on thoracic aortic disease in their curricula.

Adolescent↗
PubMed2004

Distal aortic perfusion during aortic arch reconstruction: another tool for the aortic surgeon.

Complex aortic arch reconstruction remains one of the greatest challenges facing cardiothoracic surgeons today. Deep hypothermic circulatory arrest is the most common technique for open arch replacement. Either antegrade or retrograde cerebral perfusion is often utilized in an attempt to decrease neurologic complications. In addition to cerebral perfusion, we have employed continuous perfusion of the thoracic aorta to minimize spinal cord, visceral, and lower extremity ischemia. This approach does not significantly increase the complexity of the operative procedure while reducing the ischemic time of critical areas, which may lead to improved patient outcomes.

Aorta, Thoracic↗
PubMed2004

Heme-oxygenase-1 expression correlates with severity of acute cellular rejection in lung transplantation.

BACKGROUND: Heme-oxygenase-1 (HO-1) has been shown to play an important role in oxidative stress, and recent studies indicate that it is a graft survival protein in cardiac and liver transplant models. Our laboratory previously found HO-1 to be increased in human lung allografts with acute cellular rejection (ACR) and in active obliterative bronchiolitis. To better understand the role of HO-1 in ACR we studied the relationship between HO-1 expression and ACR in a rodent model of lung transplantation. STUDY DESIGN: Orthotopic left lung transplantation was performed from Lewis (donor) to Sprague-Dawley (recipient) rats, and ACR (Grade A0 to A4) was evaluated at days 3, 5, and 7. HO-1 expression was assessed by immunohistochemistry and Western analysis, and compared with the degree of ACR. Myeloperoxidase staining was evaluated as an indirect measure of oxidant stress. Donors and recipients were also treated with either an inhibitor of HO activity, tin protoporphyrin or an inducer, cobalt protoporphyrin, and the severity of ACR was compared with that in untreated allografts. RESULTS: HO-1 expression was elevated in transplanted versus native lungs or isografts, and the degree of elevation was closely correlated with ACR grade (p < 0.001). Similarly, myeloperoxidase expression increased with time and severity of ACR. Administration of the metalloporphyrins, tin protoporphyrin and cobalt protoporphyrin, produced no significant difference in the degree of ACR, but did alter the severity of ischemia-reperfusion injury. CONCLUSIONS: Similar to what occurs in human lung transplantation, HO-1 expression is increased in a rodent lung transplant model of ACR and correlates with the severity of rejection. Altering its expression does not appear to affect the degree of ACR.

Animals↗
PubMed2004

Effects of sildenafil analogue UK 343-664 on a porcine model of acute pulmonary hypertension.

BACKGROUND: Sildenafil (Pfizer Pharmaceuticals, Sandwich, Kent, UK) has been associated with pulmonary vasorelaxation. A more potent Sildenafil analogue (UK 343-664 [Pfizer Pharmaceuticals]) has been developed, but its effects in vivo have not been studied. This study evaluated the effects of UK 343-664 (Pfizer) during acute pulmonary hypertension. METHODS: Fourteen adult swine were anesthetized with 1 minimum alveolar concentration isoflurane and were mechanically ventilated with an FIO(2) of 50%. End tidal CO(2) was maintained between 32 and 36 mm Hg. Micromanometer tipped catheters were placed in the ascending aorta, pulmonary artery, and right ventricle. Pulmonary flow was measured with a perivascular probe using transit time ultrasound. RESULTS: Pulmonary hypertension was induced with a continuous infusion of the thromboxane analogue U46619. Animals were randomized into two groups. Group 1 (n = 9) received 500 microg of UK 343-664 (Pfizer) intravenously for more than 2 minutes. Group 2 (n = 5) served as the control group. Data were recorded continuously for 60 minutes. Statistical analyses were performed with the analysis of variance and t tests. A p less than 0.05 was considered significant.Pulmonary hypertension was achieved in all animals. The administration of UK 343-664 (Pfizer) was associated with a significant decrease in pulmonary artery pressure (30.3%; p < 0.05) and pulmonary vascular resistance (42%; p < 0.05) with mild systemic vasodilatation. These effects were partially maintained at 30 minutes (a 17.3% and 39% decrease, respectively; p < 0.05). CONCLUSIONS: The administration of UK 343-664 (Pfizer) was associated with predominant pulmonary vasodilatation without systemic hypotension. This may represent a significant advance in the treatment of acute pulmonary hypertension. Potential clinical implications for this new phosphodiesterase enzyme type V (PDEV) inhibitor merit further study.

Acute Disease↗
PubMed2004

Jehovah's Witnesses requiring complex urgent cardiothoracic surgery.

Blood-sparing surgical technique and perioperative medical management allows complex surgery in Jehovah's Witnesses. The authors review four cases of urgent cardiothoracic surgery performed on Jehovah's Witnesses. No lasting sequelae associated with either bleeding or end-organ ischemia were noted. Cardiopulmonary bypass management, meticulous hemostatic operative technique, and pharmacologic support of hemostasis and erythropoiesis permit this complex surgery.

Adult↗
PubMedDate not supplied

Managing the post-left ventricular assist device patient.

The implantation of ventricular assist devices allows the opportunity for patients with intractable heart failure to have improved quality and quantity of life. The devices may be implanted after failed attempts to wean from bypass, as a bridge to transplantation, or as destination therapy. Key issues following the implantation of assist devices include the prevention of right ventricular failure, appropriate pharmacologic management, prevention and management of infection, and detection and treatment of device dysfunction.

Assisted Circulation↗