What sanctions do you mean, specifically? The US had barely any sanctions against Venezuela. Most sanctions were against members of the regime, not the country. The US remained the biggest customer for Venezuelan oil long after Chavez gained power.

https://en.wikipedia.org/wiki/Sanctions_during_the_Venezuelan_crisis

Early sanctions came in response to repression during the 2014 and the 2017 Venezuelan protests, and activities both during the 2017 Constituent Assembly election and the 2018 presidential election. Sanctions were placed on current and former government officials, including members of the Supreme Tribunal of Justice(TSJ) and the 2017 Constituent National Assembly (ANC), members of the military and security forces, and private individuals accused of being involved in human rights abuses, degradation in the rule of law, repression of democracy, and corruption. Canada and the E.U. began applying sanctions in 2017.

Chavez took power in 1999. More than a decade before these sanctions started.

The utter mismanagement by the Chavistas in power are the main reason Venezuela has been doing badly for years leading to a fucked economy, rising crime, lacking healthcare and food.

https://en.wikipedia.org/wiki/Hugo_Chávez

The high oil profits coinciding with the start of Chavez’s presidency^[15]resulted in temporary improvements in areas such as poverty, literacy, income equality and quality of life between primarily 2003 and 2007,^[16][15][17] though extensive changes in structural inequalities did not occur.^[18] On 2 June 2010, Chávez declared an “economic war” on Venezuela’s upper classes due to shortages, arguably beginning the crisis in Venezuela.^[19] By Chávez’s death in 2013, economic actions performed by his government during the preceding decade, such as deficit spending^[20][21][22] and price controls,^[23][24] proved to be unsustainable, with Venezuela’s economy faltering. At the same time, poverty,^[15][25] inflation^[26] and shortages increased.

Of course, of course. Nothing to do with corruption and incompetence of an authoritarian regime.