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Biomedical subjects

Thomas M Bashore

Publications and source records attributed to Thomas M Bashore.

At least 19 recordsLinked to original sources
PubMed2006

Update on infective endocarditis.

With infective endocarditis afflicting 15,000 patients each year and with a mortality rate that still hovers at almost 40%, the disease remains a very serious health problem. Surprisingly, the incidence has not declined over the last 30 years, and now with more health care interventions, such as pacer/defibrillators, and an increasingly elderly population with degenerative valvular heart disease, the number susceptible to endocarditis is actually increasing. Given the weak evidence for endocarditis prophylaxis, there remains a large population at risk. Much has been learned recently about the pathogenesis of endocarditis, including the role of endothelial damage, platelet adhesion, and microbial adherence to the vegetation or intact valvular tissue. Three-fourths of patients have preexisting structural heart disease. Once infection is manifest, major cardiac complications include congestive heart failure, embolization, mycotic aneurysms, renal dysfunction, and abscess formation. The diagnosis of endocarditis has been enhanced recently by modifications in the Duke criteria to include the use of transesophageal echocardiography and microbial antibody titers. Surgery continues to play an important role, with criteria for emergency, urgent, and early surgery now defined. The major organisms involved in infective endocarditis include streptococci and staphylococcus (representing 75% or so of all cases). Enterococcal infections account for many of the remaining cases, although small series and case reports suggest almost all organisms that infect humans can be implicated at times. A sizeable number of "culture-negative" cases still occur despite all the improvements in diagnostic methodology. Recent guidelines for the diagnosis, treatment, and management of infective endocarditis from the American Heart Association are reviewed and the issues surrounding prophylaxis are summarized. International cooperative databases are now being developed that hold promise for a continual reexamination of the epidemiology of this highly aggressive disease and may help provide sorely needed prospective trial data that will enhance our understanding and treatment.

Anti-Infective Agents↗
PubMed2006

Peripheral blood levels of matrix metalloproteinases in patients referred for percutaneous balloon mitral valve commissurotomy.

BACKGROUND AND AIM OF THE STUDY: Inflammation may play a central role in the progression of stenotic valvular heart disease. Serum levels of matrix metalloproteinases (MMPs), markers of extracellular matrix (ECM) turnover and potential markers of active inflammation, have been recently demonstrated in several inflammatory processes. The present study was designed to examine whether systemic evidence of ECM turnover was present in advanced stenotic mitral valve disease. METHODS: Serum levels of MMP-1, -3 and -9 were measured in 114 patients with mitral stenosis referred for percutaneous balloon mitral valve commissurotomy, and compared to those in 48 healthy, age- and gender-matched controls. RESULTS: Serum levels of MMP-1, -3 and -9 did not vary according to hemodynamic profile or heart failure class at the time of blood sampling. Levels of MMP-1 and -3 were not significantly different between those patients with mitral stenosis and controls. The level of MMP-9 was significantly higher in patients with mitral stenosis than in controls, and did not appear to be altered by commissurotomy. CONCLUSION: Serum levels of MMP-9 were elevated in patients with mitral stenosis, providing further evidence that inflammation and ECM remodeling plays an important role in the pathophysiology of valvular heart disease.

Adult↗
PubMed2006

Unusual cardiomyopathies: ventricular noncompaction and takotsubo cardiomyopathy.

With improved imaging techniques, such as cardiac magnetic resonance imaging and computed tomography, 2 unusual cardiomyopathies have been added to the differential diagnosis of nonischemic dilated cardiomyopathies. Ventricular noncompaction (VNC) classically affects the left ventricle, although right ventricular involvement can also be seen. Symptoms can be absent or can be consistent with varying degrees of heart failure and arrhythmias. VNC can initially present in all age groups, from neonates to the elderly. In takotsubo cardiomyopathy, the characteristic appearance of the left ventricle involves transient regional dysfunction of the apex and mid-ventricle, with hyperkinesis of the basal segments. Classically, it occurs after an emotionally stressful event, and it predominantly affects postmenopausal women. This article reviews characteristics of these unique cardiomyopathies.

Cardiomyopathy, Dilated↗
PubMed2005

A nitric oxide processing defect of red blood cells created by hypoxia: deficiency of S-nitrosohemoglobin in pulmonary hypertension.

The mechanism by which hypoxia [low partial pressure of O(2) (pO(2))] elicits signaling to regulate pulmonary arterial pressure is incompletely understood. We considered the possibility that, in addition to its effects on smooth muscle, hypoxia may influence pulmonary vascular tone through an effect on RBCs. We report that exposure of native RBCs to sustained hypoxia is accompanied by a buildup of heme iron-nitrosyl (FeNO) species that are deficient in pO(2-)governed intramolecular transfer of NO to cysteine thiol, yielding a deficiency in the vasodilator S-nitrosohemoglobin (SNO-Hb). S-nitrosothiol (SNO)-deficient RBCs produce impaired vasodilator responses in vitro and exaggerated pulmonary vasoconstrictor responses in vivo and are defective in oxygenating the blood. RBCs from hypoxemic patients with elevated pulmonary arterial pressure (PAP) exhibit a similar FeNO/SNO imbalance and are thus deficient in pO(2)-coupled vasoregulation. Chemical restoration of SNO-Hb levels in both animals and patients restores the vasodilator activity of RBCs, and this activity is associated with improved oxygenation and lower PAPs.

Animals↗
PubMed2005

The response to inhaled nitric oxide in patients with pulmonary artery hypertension is not masked by baseline vasodilator use.

BACKGROUND: Assessment of pulmonary vasodilator responsiveness is important in determining the prognosis and management of patients with pulmonary hypertension. Many patients, however, are already on vasodilators at the time of testing. It is unclear if these agents should be temporarily discontinued to improve the sensitivity of testing. METHODS: We examined the hemodynamic effects of nitric oxide (NO) inhalation in 60 patients with pulmonary arterial hypertension. Thirty-one of these patients were receiving medications with vasodilating properties. Vasodilator testing was performed with invasive measurement of pressure of the right side of the heart at baseline and during inhalation of 40 ppm NO. RESULTS: No significant demographic differences were seen between patients receiving and not receiving vasodilators. Similar reductions in mean pulmonary artery pressure (19 +/- 12% vs 20 +/- 12%, P = .734) and pulmonary vascular resistance (31 +/- 18 vs 32 +/- 16, P = .967) were seen in patients receiving and not receiving vasodilators. Using the definition of positive vasodilator response (> or = 20% drop in mean pulmonary artery pressure), 55% (17/31) of patients in the baseline vasodilator group had a positive response compared with 62% (18/29) of the patients not on vasodilators (P = .570). CONCLUSIONS: Concurrent use of oral vasodilators does not appear to mask a significant response to inhaled NO on the pulmonary vasculature. Therefore, routine discontinuation of pulmonary vasodilators is likely unnecessary before vasodilator testing in patients with pulmonary arterial hypertension.

Administration, Inhalation↗
PubMed2005

The emerging role of percutaneous intervention in adults with congenital heart disease.

Adults with congenital heart disease (CHD) constitute a patient population that has grown rapidly, due to advances in diagnosis and treatment of children with CHD. Though ideally served by cardiologists with advanced training in congenital conditions, adults with CHD often receive the majority of their care from primary care physicians and general cardiologists. These patients often have unique clinical presentations. An understanding of available therapeutic modalities can assist clinicians in the timing of subspecialty referral. This review focuses on the unique challenges of cardiac catheterization and the role of percutaneous interventions in adults with CHD.

Adult↗
PubMed2004

Usefulness of percutaneous balloon mitral commissurotomy in preventing the development of atrial fibrillation in patients with mitral stenosis.

A prospective cohort of patients with mitral stenosis and no history of atrial arrhythmias showed no decrease in the incidence of atrial fibrillation (AF) after successful versus unsuccessful Inoue balloon percutaneous balloon mitral valve commissurotomy. Advanced age and left atrial dimension best predicted which patients developed AF during follow-up, whereas percutaneous balloon mitral valve commissurotomy procedural success and left atrial pressure reduction did not have an impact on incidence of AF.

Adult↗
PubMed2004

Five-year clinical and echocardiographic evaluation of the Das AngelWings atrial septal occluder.

BACKGROUND: The late outcome of patients treated with atrial septal occluder devices remains incompletely defined. The purpose of this study was to assess the late outcome (range 4-7 years postprocedure) of patients in whom the Das AngelWings septal occluder device was implanted in the atrial septum. We report the clinical and echocardiographic outcome, at an average of 5 years following the procedure, of patients treated with the Das AngelWings device used to close either a secundum atrial septal defect (ASD) or a patent foramen ovale (PFO). METHODS: Thirty-two patients underwent successful percutaneous closure of an atrial septal closure, patent foramen ovale, or fenestration in the lateral tunnel of their Fontan with the Das AngelWings device between June 1995 and March 1998 at Duke University Medical Center. Two of the 32 patients were lost to follow-up. The remaining 30 patients were divided into 3 groups based on indication for device implantation. Group 1 consisted of 14 patients with a secundum ASD and predominantly left-to-right atrial shunting. Group 2 consisted of 8 patients who had a PFO and who suffered a thromboembolic event. Group 3 (compassionate use) consisted of 10 patients with multiple comorbid medical problems with predominantly right-to-left shunting at the atrial level causing hypoxemia. Eight of the patients in group 3 were severely ill at the time of device implantation. The 2 remaining patients in group 3 underwent AngelWings implantation for closure of right-to-left shunting through a Fontan fenestration. Mean follow-up was 59 months. RESULTS: There was no device embolization. No patient in the ASD or PFO/stroke group had a clinical complication. By radiographic examination, 2 of 27 patients had evidence of fracture of the nitinol framework at 2-year follow-up. Residual shunting was present in 44% at 24 hours, 20% at 1 year, and 18.8% at 2 years by use of Doppler color flow imaging and/or microcavitation echocardiographic studies. Mild mitral regurgitation caused by the AngelWings device occurred in 1 patient. One patient in the compassionate use group had a subsequent neurologic event. Five of the 10 patients in the compassionate use group died of comorbid illnesses in follow-up, none directly related to device complications. CONCLUSION: The late clinical outcome of secundum ASD and PFO/stroke patients in this study demonstrates that Das AngelWings closure of the atrial septum is effective and safe. These data are encouraging with respect to the expanding use of other percutaneously implanted ASD occlusion devices, although late clinical safety and efficacy data are needed for the specific devices being implanted.

Adolescent↗
PubMed2003

Valvular heart disease.

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Angiotensin-Converting Enzyme Inhibitors↗