There is more or less an iron law of finance: If the interest rate is higher than the nominal growth rate on the income source servicing that debt, then eventually interest expenses will eat all your income. I looked at the numbers for Italy and the picture is quite gloomy. Until the crisis really accelerated in mid-2008, the Italian economy's annualised growth rate was more or less equal to the mid-term interest rate paid on new government debt. This led to a stable debt-to-GDP figure from 2000-2008. However, since the crisis this spread between the economic growth rate and interest rate has widen quite substantially to around minus four percent. The obvious outcome has been a significant upward move in the debt-to-GDP ratio. More troublesome, the latest relief in the spread has only come about due to ECB intervention (LTRO's and rhetoric about the new bond programme) and not an acceleration in nominal growth which is pretty much flat.