Complex sentence: Benyamini, Medalion and Garfinkel (2007) study wanted to find if positive and negative of interactions that are between the patients who have heart disease and their spouse can cause spouse support and spouse undermining.
Split into simpler sentences: Benyamini, Medalion and Garfinkel (2007) study used heart patients who already had heart disease. The intentions of the study was to find if positive and negative of interactions that are between the patients who have heart disease and their spouse can cause spouse support and spouse undermining.