It's like trying to flush the toilet and take a shower when your water pipes are plugged with calcium. You can do either one but not both very well.
Since the interior wall of my left main ruptured, I have not been able to eat and then do anything strenous. If I walk fast or uphill after eating a large meal, I encounter angina.
It has to do with the autonomic system which prepares the body for food digestion. The coronary arteries are constricted to provide more blood flow to the stomach and digestive tract. In someone who only has a small percentage of normal flow through a large coronary artery, this restricts the remaining flow enough to create angina.
Actually your husbands depression could be linked to this chemistry. When you really start looking into the Acetylcholine chemistry, you begin to see that the same forces which provide vasodilation and vasoconstriction affect the nervous system. Research into depression, schizophrenia, and Alzheimers get into the same chemicals that affect the heart.
The reality is that your husband can't and shouldn't eat like he used to. Doing things the way that you always did them will not stop the progression of cardiovascular disease. He must radically change his habits, if he wants to live.
I walk for 45 minutes in the morning before I eat and then eat some cereal and fruit with non-fat milk. The same goes for lunch. I walk for 45 minutes first and then have something light and non-fat.
I have created a whole program for myself to live with coronary artery disease. It involves diet, cholesterol and BP medications, vitamins, supplements and health foods, exercise, and a daily change of attitude. Also enjoying the moment, because we never know how long we might live.
To combat depression, I suggest that your husband start walking, in the morning, before breakfast and at noon, if possible. Also I would suggest at least a multi-vitamin, B complex, and a high dose of folic acid and Vitamin E at the least.
Green tea might be the most effective at combating vasoconstriction. The prescription nitrates, such as Imdur are dead ends, if you want to improve your condition.
A couple of years ago I used St. John's Wort, successfully for depression but no longer need it. Any substance that increases circulation is probably also good for depression.
Angina can be provoked by heavy meals as well as by walking, as each of these activites can cause increased demands on the heart. However, if it is angina that he is experiencing, he needs to let his cardiologist know this. The listlessness and lack of interest in anything sound like symptoms of depression - you ought to let his internist know about this.