Actually we do have something specifically for hypertension which is called Healthy Heart: Guided Imagery for Healthy Cholesterol, Open Arteries and a Strong Heart. (It targets hypertension, the narrowing of the arteries, the accruing of plaque and all the attendant issues connected with this.) Also, Emmett Miller's Down with High Blood Pressure is very good and his hypnosis/imagery would work well for this too.
But you're right - any de-stressing or relaxation CD would work to some extent for hypertension. If you want one of mine, there’s Relaxation & Wellness, Relieve Stress or General Wellness.
But we have so many other stellar ones, I hardly know where to begin. Bodhipaksa’s Guided Meditations for Stress Reduction; Sacred Pause by Karen Sothers; Jon Kabat-Zinn’s Mindfulness Meditation; A Moment’s Peace by Tracy Carreon; Letting Go of Stress by Emmett Miller & Stephen Halperin; Jim Porter’s A Day Away from Stress; David Illig’s Reduce Stress & Anxiety and more. Any one of these will slow you down, relax and open the blood vessels, and certainly shift biochemistry to counter some of the effects of running too much cortisol and adrenaline.
I hope this helps. Take care,