R1, as Helena says, is ruido 1, more propertly the "primer tono cardiaco", and in English the "first heart sound". It is commonly referred to in English as S1. "Desdoblamiento", as you say, is splitting, meaning that there is a delay or separation between the two components of S1, known as M1 and T1, meaning the closure of the mitral and tricuspid valves respectively. It often indicates a dysfunction such as a left bundle branch blockage.
https://en.wikipedia.org/wiki/Heart_sounds
https://es.wikipedia.org/wiki/Ruido_cardíaco

"Splitting of S1:
The first heart sound is made up of several components, although the most audible components heard at the bedside are the high frequency vibrations related to mitral and tricuspid closure. Generally, the louder sound of mitral closure drowns out the softer sound of tricuspid closure. Occasionally the two are separated sufficiently such that there is audible splitting of S1, heard best at the apex or lower left sternal border."
http://accesspharmacy.mhmedical.com/data/InteractiveGuide/ph...

FAo, as Helena also suggests, stands for foco aórtico. This abbreviation seems to be used mostly in Portuguese; in Spanish FA is standard. But that must be what it means here:

"Ausculta cardíaca
foco aórtico (FAo): no segundo espaço inter-costal direito, junto ao Esterno"
http://www.enciclopedia.med.br/wiki/Ausculta_cardíaca

"FM: foco mitral. FA: foco aórtico. FP: foco pulmonar. FT: foco tricuspideo. R1: primer ruido cardíaco. R2: segundo ruido cardíaco."
http://www.monografias.com/trabajos80/diagnostico-diferencia...

"Foco aórtico: segundo espacio intercostal derecho."
http://www.gastromerida.com/secciones/semiologia/corazon/aus...

It's an auscultation site, and is called the aortic area in English:

"The murmur of aortic stenosis is typically a mid-systolic ejection murmur, heard best over the “aortic area” or right second intercostal space, with radiation into the right neck."
http://www.wilkes.med.ucla.edu/Systolic.htm

And "preferentemente" probably means "predominantly" rather than "preferably" here:
http://www.proz.com/kudoz/spanish_to_english/medical_general...