The points below have been extracted from Lama Zopa Rinpoche's commentary on this text, given in New Zealand, October 1994:
What is a heart-spoon? When you're eating, you use a small spoon to extract the very best portion of the food in front of you. Similarly, this teaching on impermanence and death by Pabongka Dechen Nyingpo helps you extract the most precious essence from this human life: the ability to secure the happiness of all future lives, liberation from cyclic existence, and enlightenment for the sake of all sentient beings.
The evil thought of the worldly concerns—supported by the concept of permanence—is constantly attacking us, interfering with our practice of Dharma, and preventing the actions of our daily life from becoming pure Dharma. The advice of the great Gelug lama Pabongka Dechen Nyingpo contained in this teaching is extremely powerful in destroying the concept of permanence and the evil thought of the worldly concerns.
Reading this teaching is similar to seeing a corpse: it brings your mind back to earth from its usual state of distraction, thoughts scattered like leaves in a gale. Instead of being distracted by hallucinations and wrong conceptions, you are caused to think deeply about your forthcoming death and what will happen to your consciousness at that time, what kind of life your next one will be. Such thoughts lead to the realization that you must practice Dharma continuously from now on. This is the only way to ensure a happy death.
You can find The Heart's Utmost Need PDF (formerly known as Heart-Spoon) in the FPMT Catalogue.