Biomedical subjects

Nizar A Yonan

Publications and source records attributed to Nizar A Yonan.

3 recordsLinked to original sources

PubMed2003

Transforming growth factor beta and diastolic left ventricular dysfunction after heart transplantation: echocardiographic and histologic evidence.

BACKGROUND: The mechanism for chronic left ventricular diastolic dysfunction in the non-rejecting cardiac allograft has not been fully studied. OBJECTIVES: The purposes of this study were to analyze the significance and frequency of left ventricular diastolic dysfunction after heart transplantation and to examine the involvement of fibrotic cytokines (transforming growth factor beta [TGF-beta]) in development of clinical and echocardiographic changes in cardiac allograft recipients. METHODS: We studied 152 heart transplant recipients who had survived for at least 24 months. We compared histopathologic findings (staining of endomyocardial biopsy specimens using hematoxylin and eosin, and polyclonal antibodies expressed as TGF-beta score), left ventricular function (Doppler echocardiography), and clinical course (New York Heart Association [NYHA] status). We classified patients into Group 1 (n = 41 recipients) with a restrictive filling pattern, mitral deceleration time (MDT) <140 milliseconds, and Group 2 (n = 111 recipients), MDT >or=140 milliseconds. RESULTS: The MDT was 122 +/- 7 milliseconds in Group 1 compared with an MDT of 177 +/- 17 milliseconds in Group 2 (p = 0.0003). Group 1 showed significant immunohistochemical staining in endomyocardial biopsy specimens (a mean TGF-beta score of 9.1 +/- 1.2 for Group 1 compared with a mean TGF-beta score of 3.6 +/- 0.8 for Group 2 p = 0.001). The TGF-beta expression correlated inversely with both MDT and isovolumic relaxation time (r = -0.77, p = 0.0004, and r = -0.69, p = 0.004, respectively). Mean NYHA status in Group 1 recipients was 2.2 +/- 1.1 compared with 1.37 +/- 0.6 for Group 2 (p = 0.006). CONCLUSIONS: Transforming growth factor beta expression in cardiac allografts is associated with impaired left ventricular diastolic function. The pathogenesis of diastolic dysfunction may be an aberrant repair process after rejection-caused TGF-beta expression in the allograft.

Adult↗

PubMed2002

Pulmonary vein gas analysis for assessing donor lung function.

BACKGROUND: Radial artery oxygenation (PaO2) is the standard method for assessing potential lung donors. This study was proposed to assess the use of pulmonary vein gases (PvO2) in selection of donor lung for transplantation. METHODS: We studied 170 lungs from 85 consecutive donors. Lungs were classified into group A, PaO2 and PvO2 > 300 mm Hg; group B, PaO2 < 300 mm Hg, and PvO2 > 300 mm Hg; and group C, PvO2 < 300 mm Hg. RESULTS: Lungs retrieved from group A and group B were used for transplantation. Allograft function, assessed by the arterial and alveolar oxygen tension ratio, was similar at 12 hours and at 24 hours after operation (0.69, 0.73, vs 0.70, 0.71, for groups A and B, respectively (p = 0.8, 0.7, respectively). Similar radiologic appearance was seen in both groups (p = 0.2). Median duration of intubation was also similar (p = 0.6). The 30-day mortality rate was 12% versus 11.3% (p = 0.8), and 1-year survival rate was 80% versus 82% (p = 0.8) for recipient received lungs from group A and B donors, respectively. CONCLUSIONS: Selective pulmonary veins analysis gives an accurate assessment of individual gas exchange in comparison with arterial PaO2, identifying more potential donor lungs for transplantation.

Adult↗

PubMed2002

Clinical significance of tricuspid valve dysfunction after orthotopic heart transplantation.

OBJECTIVES: Tricuspid regurgitation (TR) is common after heart transplantation (OHT), but its clinical relevance is undetermined. This study documents the clinical progress of patients with TR after OHT in relation to the severity of TR. METHODS: We studied 238 transplant recipients who had survived for at least 12 months after OHT. Tricuspid regurgitation was graded clinically and by assessing regurgitant jet area. Recipients were divided into those with no TR Group 1 (n = 64), those with sub-clinical TR (TR absent clinically and regurgitant jet area <25%, Group 2 (n = 89), and those with clinical TR (with clinical TR or regurgitant jet area > or =25%, Group 3 (n = 85). RESULTS: We found no significant difference among the groups in terms of age, or pre-operative events. At 12 months after OHT, mean right atrial and pulmonary artery pressures were higher in Group 3 than in Group 1 or Group 2 (p = 0.005 and 0.03, respectively). Right ventricular end-diastolic and end-systolic volumes were smaller for recipients in Groups 1 and 2 compared with those in Group 3 (p = 0.01 and 0.02). The annual development of renal impairment was 0.019 (95% confidence interval [CI], 0.014-0.029), 0.026 (95% CI, 0.022-0.62), and 0.613 (95% CI, 0.346-0.756) in Groups 1, 2, and 3, respectively (p = 0.02). At the most recent follow-up, mean New York Heart Association class for Group 1 was 1.4, for Group 2 was 1.7, and for Group 3 was 2.7 (p = 0.04). CONCLUSIONS: The integrity of the tricuspid valve has a significant impact on long-term clinical progress of OHT recipients. Recipients with significant TR are more symptomatic and have poorer right-sided heart function compared with those with mild or no TR.

Adult↗