Our Team

Nathaniel Arana
Founder & CEO
NGA Healthcare’s principal, Nathaniel Arana, has many years experience in business and in the healthcare field. Nathaniel earned a management degree from the Eller College of Management with an emphasis in operational management and organization. He helped start an out-of-network billing and consulting business from concept to profitability. Thereafter, he managed and grew a healthcare consulting business; under his management, the business dramatically increased its revenues and clients.
Nathaniel started NGA Healthcare because he found that practices were looking for consulting companies that could provide results—not just empty promises. Since then, NGA Healthcare has worked with all specialties to help grow, reorganize and make practices more profitable. Nathaniel regularly contributes to many healthcare business magazines and companies as an expert in practice management. A physician advocate, Nathaniel believes in working directly with his clients to achieve, and surpass, their goals.
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Renee Vaughn
Vice President of Strategy
Renee Vaughn joined NGA with over 20 year in the healthcare industry across payer and provider. Her focus and passion has always been in strategy, partnerships and operations. She focused her early career on understanding revenue cycle and the drivers for underpayments within hospitals and physician practices She then transitioned to working and developing the strategy for some of the largest payers, United Healthcare and Centene. Renee loves the overlap between healthcare and strategy.
Renee was raised on the East Coast. With degrees from both Duke University in North Carolina and Wharton in Pennsylvania, Renee has had to adapt to sunny Tucson when moving here. She enjoys living in Arizona and avoiding cold winters.
She also shares in NGA’s mission to help clients get what they rightfully deserve from the payers. She hopes to continue to help NGA develop and refine the strategies to continue our 100% guarantee.

Erika Torres
Vice President of Network Management
As the Vice President of Network Management at NGA Healthcare, I bring a distinguished and multifaceted background spanning Contract Management, Provider Servicing, and Managed Care Operational Development, cultivated over a tenure exceeding two decades in the healthcare domain. My unyielding commitment as both a health and physician advocate radiates through my active engagement in negotiating contracts with physicians, specialists, and ancillary provider networks, laying the groundwork for my esteemed tenure at NGA Healthcare, commencing over three years ago.
Throughout my tenure at NGA, I have wholeheartedly embraced the role of mentorship, guiding my esteemed team members to ascend into team leads and assume pivotal leadership positions within the management hierarchy. My fervent passion and unwavering dedication to nurturing talent persist as I relentlessly foster the growth and development of emerging talents within both the Contract Specialist and Provider Services teams under my watchful stewardship.
Originally hailing from New York, I made a decisive transition to Lake Mary, Florida in the early 90s, where I have since established an indomitable presence.
Beyond the realm of professional obligations, the focal point of my endeavors orbits around my cherished daughter, who, at the tender age of 4, was diagnosed with autism. This deeply personal journey has ignited an unwavering flame of passion within me, propelling me to champion the cause of awareness, education dissemination, and spearheading fundraising endeavors for autism causes. Additionally, I humbly serve as the Secretary on the esteemed Board of Directors for my daughter's non-profit dance studio, generously dedicating my time and resources to fortify community fundraising initiatives.
I eagerly anticipate the opportunity to harness and leverage my profound knowledge and expertise from the insurance industry at NGA Healthcare. With an indefatigable spirit and boundless enthusiasm, I embrace each passing day as a sacred opportunity for perpetual growth, welcoming challenges with open arms, and seizing every fleeting opportunity that manifests itself before me.

Lisa Aguilar
Director Credentialing /Client Services Team
A Southwest Arizona native, born and raised in Tucson, AZ. Lisa has over 30 years of healthcare management experience in physician private practice and hospital patient access management. Her healthcare management experience provides her with a strong devotion to our NGA Healthcare clients/providers with knowledge and understanding of Insurance companies credentialing requirements.
Lisa enjoys the challenge of working with the insurance companies. She finds fulfillment after receiving those notifications that our provider enrollment dates are effective and everyone is properly loaded.
Favorite Quote: Be true to yourself and grateful for the new day!

Erick Fonseca
Network Management Manager
Erick Fonseca, Network Management Manager at NGA Healthcare, blends international affairs expertise with hands-on contracting experience to drive impactful changes. With a bachelor's degree in international affairs, Erick's early career included a pivotal role at the comptroller general's office in Venezuela. There, he honed his skills in legal language, economy, and politics. Despite having no prior experience in the US healthcare system, having been born and raised in Venezuela, Erick quickly rose through the ranks under the mentorship of Erika Torres, now supervising negotiations and driving favorable outcomes through persistence, thorough review of information, and leveraging previous experience.
His years at NGA Healthcare are marked by his role as the principal architect of training programs in the Network Management department, where he collaborated in nurturing and elevating numerous team members into leadership roles, fostering a culture of growth. Erick's commitment to innovation and operational excellence has significantly contributed to NGA Healthcare's success in delivering top-tier consulting services to medical practices across specialties and his journey from starting with no prior knowledge to becoming a key leader in the company showcases the dedication, hard work, and passion NGA Healthcare delivers to all clients.

Justin Stickel
Lead Software Developer Manager
Justin Stickel has been building analytic data tools for over 15 years. After graduating from the University of Pittsburgh with a degree in Astrophysics and Mathematics, he leveraged coding skills developed in his research on Gravitational Radiation to create a career in programming and data science. Justin has worked with hospital systems, created transformation tools for genetic data, contributed to web tools for sharing craniofacial and dental genetic data, and worked in the news startup industry creating content classification and recommendation algorithms. Now at NGA Healthcare, he is working to show how technology can push the industry of medical credentialing and contract negotiation forward, enabling physicians to get clarity on their compensation, and grant insights into a historically opaque sector.
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Luis Felipe Mata
Data Analytics Manager
Luis Felipe brings a unique combination of engineering expertise and a passion for innovation to his role at NGA Healthcare. Born in Venezuela, his drive to solve complex problems and his desire to make a positive impact in the lives of the providers who are against a healthcare system that isn’t designed to support them, fueled his pursuit of this role.
Leveraging his strong foundation in analytical thinking and problem-solving, Luis Felipe has become a key player in NGA's negotiation team. Over the past two years, he has played a pivotal role in improving the reimbursement rates for healthcare providers across multiple states, directly impacting hundreds of negotiations.
In his role, Luis Felipe meticulously analyzes contract data, compares rates, evaluates offers, and reviews contract language to identify areas for improvement. He then proposes strategic solutions and collaborates effectively across departments to ensure the best possible outcomes for our clients.
Luis Felipe's keen eye for detail, combined with his exceptional communication skills, fosters a work environment that encourages the development of new ways to improve our already robust system. He is a valuable asset to the NGA Healthcare team, consistently working to ensure our clients receive the fair reimbursements they deserve.

Annie Fields
Client Success Manager
Annie is a dedicated Accounts Receivable Specialist at NGA, where she applies her expertise in auditing and business process management. Her passion lies in optimizing reimbursement rates for healthcare practices, ensuring they receive the compensation they deserve from insurance payers. At NGA Healthcare, Annie leverages her skills to enhance practice reimbursement rates, directly improving patient care.

Ken Riesgo
Sales and Marketing Consultant
With a six-month tenure at NGA Healthcare, I am dedicated to driving sales and marketing initiatives that align with the company's strategic goals. My role encompasses responsibilities, such as developing marketing campaigns, managing sales pipelines and building client relationships. Prior to joining NGA Healthcare, I honed my sales and leadership skills in the competitive equipment rental industry, where I held key positions for 10 years.
My professional background, coupled with a results-oriented mindset, has equipped me with a proven ability to build relationships and close deals. I am passionate about delivering exceptional customer service and building long-lasting partnerships.
Outside of work, I am a proud family man who enjoys golfing and spending time with family and pets. This personal balance fuels my drive and enthusiasm for achieving professional success. I am excited to contribute to NGA Healthcare's growth by building and growing relationships and making our customers see the benefits that NGA Healthcare can bring to them and their practice.

Karla Lopez
Executive Assistant to the CEO
Karla serves as the Executive Assistant to the CEO at NGA Healthcare, providing high-level, strategic support to ensure the CEO’s time is spent efficiently and effectively. With a strong background in executive operations, Karla plays a critical role in managing the CEO’s schedule, coordinating key meetings, and facilitating seamless communication between the CEO and internal teams, clients, and external partners.
Karla excels at managing complex logistics, anticipating needs, and handling confidential information with the utmost discretion. Karla’s ability to prioritize competing demands and stay ahead of rapidly changing priorities makes her an indispensable partner to the CEO, allowing leadership to focus on business growth and strategic initiatives. Known for her exceptional organizational skills, attention to detail, and calm under pressure, Karla thrives in a fast-paced environment.
Outside of work, Karla enjoys spending time with her family and friends, her two dogs, and volunteering for community service, bringing a well-rounded and positive perspective to her professional role.