Location and density of alpha- and beta-adrenoreceptor sub-types in myocardium after mechanical left ventricular unloading.

BACKGROUND: We hypothesized that not all subtypes of alpha- and beta-adrenoreceptors undergo similar upregulation and redistribution in human myocardium after mechanical unloading with an assist device. METHODS: We obtained core biopsy samples of the left ventricle in 19 patients before and after removal of a Jarvik or Thoratec left ventricular assist device (LVAD) to study the effect of mechanical unloading on the distribution of alpha- and beta-adrenoreceptors. Fresh, embedded tissue sections were incubated with receptor blockers and antibodies before the fluorescent labeling of receptors. Images were obtained by fluorescence deconvolution microscopy, and composite tissue renditions were made from the stacked images. Multiple adrenoreceptor subtypes were studied. RESULTS: We saw a reversal of myocyte hypertrophy in all patients, but the upregulation of receptors was not seen in all post-LVAD tissue samples. Furthermore, we noted receptor relocalization from an initial punctate/clumped pattern to a normal homogeneous distribution in many patients. Significant differences were seen in the distribution of beta(2)- and alpha(1)-receptors and in alpha(1A) subtypes. CONCLUSIONS: In this study we show not only the expected reversal of myocyte hypertrophy and the increase in adrenoreceptors after ventricular unloading, but also the relocalization of specific receptor subtypes.

Reversal of myocyte hypertrophy by ventricular unloading: cardiac improvement without adrenergic receptor up-regulation and relocalization.

In previous studies, we found that the improved contractile ability of cardiac myocytes from patients who have had left ventricular assist device (LVAD) support was due to a number of beneficial changes, most notably in calcium handling (increased sarcoplasmic reticulum calcium binding and uptake), improved integrity of cell membranes due to phospholipid reconstruction (reduced lysophospholipid content), and an upregulation of adrenoreceptors (increased adrenoreceptor numbers). However, in the case presented here, there was no increase in adrenoreceptor number, which is something that we usually find in core tissue at the time of LVAD removal or organ transplantation; also, there was no homogeneous postassist device receptor distribution. However, the patient was well maintained for 10 months following LVAD implantation, until a donor organ was available, regardless of the lack of adrenoreceptor improvement. We conclude from these studies that cardiac recovery is the result of the initiation of multiple repair mechanisms, and that the lack of expected changes, in this case increased adrenoreceptors, is not always an accurate indicator of anticipated outcome. We suggest that interventions and strategies have to consider multiple, beneficial changes due to unloading and target a number of biochemical and structural areas to produce improvement, even if not all of these improvements occur.

Internet use in families with children requiring cardiac surgery for congenital heart disease.

OBJECTIVE: We sought to document the prevalence of Internet access and usage patterns among families who have children with congenital heart disease presenting for cardiac surgery. DESIGN: A cross-sectional study was performed utilizing a questionnaire (10 questions) as the study tool. Statistical analysis was performed on all completed questionnaires. The chi(2) test was used to evaluate categorical variables and the t test to evaluate continuous variables. RESULTS: Two hundred seventy-five questionnaires were completed and analyzed. Thirty-seven percent (102/275) of the children had a cyanotic congenital heart defect. There were 21 children with Trisomy 21. Fifty-eight percent (160/275) of families had access to the Internet. The most common locations for accessing the Internet were home (80%; 129/160) and work (51%; 82/160). There were no significant differences in Internet access with regards to underlying individual congenital heart defect, cyanotic versus acyanotic heart defects, or congenital heart defects with functional univentricular hearts versus biventricular hearts. Families with older children (12--24 years) were more likely to have Internet access. Families of children undergoing placement of a right ventricle to pulmonary artery conduit were more likely to have Internet access. Of the 160 families with Internet access, 58% (93/160) used the Internet to obtain information related to their child's cardiac diagnosis. Eighty-two percent (76/93) characterized locating cardiology-related information as easy. Six parents created interactive personal Web sites specifically related to their child's congenital heart defect. Although families with older patients (12--24 years) were more likely to have access to the Internet, this did not translate into greater use of the Internet to obtain cardiology-related information. Among families who accessed the Internet for cardiology-related information, 95% (88/93) of families characterized the information as helpful or very helpful in furthering the understanding of their child's heart defect. CONCLUSION: Families are utilizing the Internet to educate themselves about congenital heart disease. Most parents consider the process easy and the information obtained helpful to the understanding of their child's congenital heart defect and surgery. Internet use in this patient population is expected to increase. Our vigilance in providing accurate Internet references, as well as in identifying inaccurate Internet information available to our patients and their parents, is of paramount importance.