African Annals of Thoracic and Cardiovascular Surgery 1994-7461 Academic Journals 10.5897/AATCVS.9000006 Yangni-Angate, K. H. * E-mail: 2016 30 06 2016 08 01 2016 13 05 2016 11 1 22 78 This is an open-access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://politicalwaffle.uk/journal/AATCVS/article-abstract/BF3BC2460757 The full text article is available as a PDF file from http://politicalwaffle.uk/journal/AATCVS/article-full-text-pdf/BF3BC2460757