Peripartum cardiomyopathy (PPCM) is a rare form of congestive heart failure characterized by left ventricular dysfunction that develops towards the end of pregnancy or during the early postpartum phase. Even though the majority of PPCM patients show partial or complete recovery of their heart functions, the mortality rate of PPCM remains high. Previous research has suggested that vascular dysfunction triggered by late-gestational hormones and potent anti-angiogenic factors play key roles in the pathogenesis of PPCM; however, the exact mechanisms remain elusive due to limited patient tissues for characterization. Here, we report a case of PPCM where the coronary vessels from the patient's explanted heart showed marked vascular dysfunction with impaired nitric oxide response. Importantly, these vessels exhibited deficient adenosine-mediated vasorelaxation when subjected to myograph studies, suggesting impaired Kv7 ion channels. Results from this work may lead to new therapeutic strategies for improving Kv7 function in PPCM patients.