In a small saucepan, season the artichokes with salt and pepper and simmer them in the cream over moderately low heat until very tender, about 12 minutes.
Transfer the artichokes and cream to a blender and puree. Add the lemon juice and season with salt and pepper.
In a large saucepan of boiling salted water, cook the pasta until al dente. Drain the shells and return them to the pan. Add the artichoke cream, smoked chicken, tomatoes and chives; season with salt and pepper. Transfer to bowls and serve.