"heavy debt" is correct and usable in written English.
You can use it to describe a large, burdensome amount of debt, such as: "After years of unsuccessful investments, I found myself in heavy debt."
Adding to its woes was a heavy debt load.
The old Clear foundered for various reasons, including heavy debt.
Third, Brazil still faces several years of heavy debt payments.
"It was their heavy debt loads as well".
If they do, then the "heavy debt, no degree" problem will be sharply reduced.
Kingfisher has never made a profit and has a heavy debt load.
Now that Mr. Bo has been excommunicated, news of Chongqing's heavy debt is beginning to emerge.
Jamaica suffers from low growth, declining productivity and a heavy debt burden (see chart).
At the same time, borrowing costs are rising, adding to an already heavy debt pile.
Students who leave college burdened with heavy debt are not the only ones who sacrifice.
It is essentially paying a single year's bill by adding to its already heavy debt load.
