The quad cab has a smaller back seat and a larger bed, the crew cab has a larger back seat and a smaller bed. To compare them you can go to http://www.ramtrucks.com/en/2011/ram_150... and select the Build My Own option from the bottom of the page.
Heart muscle thickening (called cardiac hypertrophy) can be a healthy response to exercise and pregnancy; however, it often occurs in people with high blood pressure, diabetes, heart failure and certain genetic conditions.
1 Pulmonary valve stenosis, which is the thickening of the pulmonary valve, therefore causing narrowing.  Mitral valve stenosis, which is the thickening of the mitral valve (of the left heart), therefore causing narrowing.