A COmplex Cloud: Dissecting the Vascular Impact of Hookah Use

Abstract

Reduction of tobacco use is a longstanding cardiovascular public health goal. A burgeoning array of novel tobacco products threaten to offset gains achieved in lowering cigarette smoking rates. Hookahs, or waterpipes, have been used for centuries, mainly in the Middle East, but their popularity has been growing worldwide. The uptake of hookah smoking in the United States has been attributed to the availability of flavored tobacco, advertising on social media, and the lack of regulation.1 Recent surveys report that 1 in 6 adults in the United States use hookahs and that most regular users are young adults, suggesting the potential for further increases in use.2 Furthermore, hookah smoking is associated with the use of other tobacco products and higher combustible cigarette consumption among youth, suggesting that hookah smoking may serve as a gateway to other tobacco products.2,3 Hookah smoking is often perceived to be safer than combustible cigarettes, largely because of the assumption that the water filters out carcinogens and toxicants and the perception that hookah uses more natural ingredients.4 Hookah smoke produced by traditional charcoal briquette heating contains particulate constituents similar to combustible cigarette smoke and delivers comparable levels of nicotine.5 However, the patterns of hookah use are different from the patterns of use of combustible cigarettes. Hookah smoking is usually intermittent, over the course of 30 to 60 minutes, and typically takes place in a social setting.2 During hookah use, charcoal briquettes heat the tobacco but do not achieve temperatures as high as combustible cigarette smoking (400°C versus 900°C).5 Consequently, hookah smoke contains higher levels of incomplete combusted products than combustible cigarette smoke, including higher carbon monoxide (CO) levels.5 More recently, an electric version of hookah (e-hookah) was developed that heats the tobacco by using a battery-powered device, much like electronic cigarettes. Whether produced by charcoal or electronic heating elements, hookah smoke contains multiple potential toxicants (Figure). The health effects of individual toxicants including flavorings and carbon monoxide remain incompletely understood. Few prior studies have evaluated the cardiovascular effects of hookah use. The burden of long-term hookah use has been associated with the presence and severity of coronary artery disease.6 Acute charcoal-heated hookah smoking has been shown to increase measures of arterial stiffness, blood pressure, and sympathetic activation.7–10 Circulating apoptotic endothelial cell microparticles were found to be higher in occasional hookah smokers than in nonsmokers, further suggesting that hookah use is associated with vascular injury.11 In vitro treatment of endothelial cells with hookah smoke extract decreased cell viability and proliferation, increased the number of cells in cell cycle arrest, increased oxidative © 2019 American Heart Association, Inc.