Background: The Kingdom of Saudi Arabia (KSA), like many other countries worldwide, is experiencing a shortage of surgeons in cardiothoracic surgery. To overcome this chronic shortage, non-medical practitioners have been introduced into the field of cardiac surgery to expand its surgical capability, referred to as 'Surgical Assistants' (SAs). Although there is growing evidence that non-medical practitioners in their extended surgical role provide safe practice and add value, and benefit the workforce environments and surgical teams, concerns about the job design of the cardiac surgical assistant workforce, such as role autonomy and job dissatisfaction have been outlined in the literature by both non-medical practitioners and surgeons, although scant empirical research has examined these concerns from the perspective of cardiac SAs themselves. Aims: To describe the current role and job design of cardiac SAs across the Kingdom of Saudi Arabia (KSA), to explore what factors influence the levels of motivation and job satisfaction amongst cardiac SAs, and to examine how the role and job design of cardiac SAs could be redesigned to enhance their motivation and job satisfaction. Methods: To accomplish this aim, three distinct studies were conducted in four phases. The first study was a narrative review (first phase), the second consisted of two phases (mixed method with sequential design), and the third was a small-scale survey (fourth phase). These phases are outlined below: (i) the first phase consisted of a narrative review study of the literature to systematically explore pertinent literature to provide evidence on the current situation of surgical care assistants' clinical outcomes within their surgical extended role, with an emphasis on the cardiothoracic surgical field. (ii) the second phase consisted of a quantitative cross-sectional survey using Morgeson and Humphrey's (2006) Work Design Questionnaire in the first phase of the mixed methods study to ascertain the perspectives of cardiac SAs on their job design across KSA and to prioritise the aspects of the cardiac SA role which need to be redesigned. (iii) the third phase consisted of a qualitative study to gain a thorough understanding of cardiac SAs' perspectives on their job design and to consider how the job could be redesigned from their perspectives. (iv) the fourth phase included a small-scale survey to establish prioritisation on recommendations for enhancing the job design of cardiac SAs across KSA. The second and third phases were sequential in nature; mixed methods with an explanatory design were used and underpinned by the Job Characteristics Theory. Findings: A review of the literature resulted in only one outdated audit-style study on the clinical outcomes of the cardiac SA workforce, conducted in the United Kingdom, two single-centre studies conducted in the United States, and no study conducted in KSA, and none of the identified studies had discussed job design concerns. In the second phase, I surveyed the job design of cardiac surgical assistants in KSA. All scalable items within the questionnaire were reported as satisfactory except for 'autonomy,' 'task identity,' 'feedback from the job,' 'job complexity,' 'social support,' 'feedback from others,' 'ergonomics' and 'work conditions.' Based on the results of this national survey, a qualitative study was conducted to gain an in-depth understanding of SAs' perspectives, examine the survey findings in greater detail and consider ways to redesign the job to address these factors from the perspective of cardiac surgical assistants. Through thematic analysis of 14 individual interviews, six themes were identified: the importance of the role, earned autonomy, lack of recognition, inconsistency of training, poor appraisal and feedback, and feeling unappreciated and undervalued. The data allowed a number of specific recommendations to be formulated that could be implemented at the service, organisational and professional levels to enhance SAs' job satisfaction. Conclusion: It is imperative that the working conditions of SAs should be further expanded to address the issues which cause lower levels of motivation and a greater intention to leave their role. While it is acknowledged that the thesis is highly contextualised for Saudi Arabia, it equally highlighted contemporary issues for the role of cardiac extended surgical team members. Thus, the results may be of interest to cardiac SAs practicing in other countries as well as other non-medical practitioners in other professions.