Many people believe that electronic cigarettes are less harmful than traditional cigarettes, but research at the University of Louisville School of Medicine has shown that electronic cigarettes have a variety of negative effects on the body. Physicians with UofL Health also have had significant experience treating patients who have experienced a wide array of negative effects from vaping.
Alex Carll, an associate professor in the Department of Physiology, studies the impacts of ingredients in vape liquids in the laboratory. Rodrigo Cavallazzi, professor of medicine in the Division of Pulmonary, Critical Care and Sleep Disorders, treats patients as director of the medical intensive care unit at UofL Health – UofL Hospital.
UofL News spoke with Carll and Cavallazzi about their findings and insights to understand how work in the laboratory echoes patients’ experience with e-cigarettes.
UofL News: Dr. Carll, what is the focus of your research and what have you discovered about the effects of vaping?
Alex Carll: We test the impacts of inhaled electronic cigarette aerosols on heart function and blood pressure. We have found that exposures to these aerosols in mice can rapidly disrupt heart rhythm, causing abnormal heart beats that occur either prematurely or are skipped.
Our studies in animal models indicate that vaping likely causes cardiac arrhythmias (abnormal heart beats) and does so by causing fight-or-flight stress responses. It increases blood pressure in humans and mice, as well. These abnormal heart beats can increase risk for fatal arrhythmias and sudden cardiac death, which have recently been associated with vaping in young adult patients.
Another recently published mouse study from our group indicates that vaping during pregnancy may cause peripartum arrhythmias, with these effects continuing well after e-cigarette cessation.
UofL News: Dr. Cavallazzi, have you seen these types of effects in your patients?
Rodrigo Cavallazzi: When I see patients, my focus is more on the respiratory system, but it is definitely conceivable that patients who vape have several consequences to their cardiovascular system, including arrhythmias, based on the load of nicotine and other potentially toxic chemical substances they are exposed to through vaping.
UofL News: What are the symptoms you most often see in patients who vape?
Cavallazzi: I see respiratory symptoms such as cough, shortness of breath, chest tightness and wheezing, which I am certain can be attributed to vaping in some patients. I also see exacerbation of underlying lung diseases such as asthma and COPD.
Some of these patients end up in the ICU. I have seen a few patients with acute respiratory failure that I believe was due to a very serious condition called “e-cigarette or vaping product use-associated lung injury” (EVALI). These patients develop acute respiratory failure that sometimes resembles severe pneumonia or a severe Covid-19 infection. The medical literature indicates that this happens when tetrahydrocannabinol (THC, the principal psychoactive constituent of cannabis) is added to an e-cigarette device and is contaminated with vitamin E acetate. It also has been reported in patients inhaling nicotine only.
The effects mentioned in Dr. Carll’s studies seem to corroborate what other authors have written on the cardiovascular effects of inhaled nicotine and other potentially toxic chemical substances through e-cigarettes.
UofL News: Dr. Carll, have you been involved in any human studies?
Carll: Yes, my lab has published two population studies detailing smoking’s adverse impacts on cardiac conduction, and we have associated some of our observations with long-term cardiovascular mortality.
Our population studies in smokers showed correlations between cotinine in the blood, a biomarker indicating nicotine exposure, and electrocardiogram (ECG) abnormalities. Some of these ECG abnormalities in smokers corresponded with increased cardiovascular mortality over a 25-year follow-up period. Additionally, some of the ECG effects associated with smoking and nicotine corresponded with changes in the fight-or-flight stress hormones norepinephrine, epinephrine and dopamine. Dopamine itself also appeared responsible for smoking-related shortening in the time between atrial and ventricular contraction.
I also have been involved in a yet-unpublished clinical trial focused on preventing smoking’s adverse impacts on heart conduction.
UofL News: Dr. Cavallazzi, how would the effects that Dr. Carll documented in the lab affect patients?
Cavallazzi: As a clinician, the chronic cardiovascular effects of combustible cigarette smoking I often see are myocardial infarction, stroke and peripheral vascular disease. The latter manifests as difficulty walking and erectile dysfunction.
UofL News: How does the knowledge we have about the effects of cigarette smoking translate to vaping? And what do you tell your patients about the health impacts of vaping and smoking?
Cavallazzi: I tell them the truth. Combustible cigarette smoking increases the risk of lung cancer development by 15 to 30 times. Up to 50% of people who smoke combustible cigarettes develop COPD. This is a much higher figure than previously thought.
Combustible cigarette smoking increases the risk of a heart attack by 4 to 7 times and increases the risk of other cancers and conditions, including peripheral vascular disease and stroke.
We are now starting to understand the risks of e-cigarette smoking: EVALI, exacerbation of asthma and COPD. There is data that daily users of e-cigarettes have more than double the odds of chronic lung disease, including chronic bronchitis, emphysema or COPD.
UofL News: How do you help your patients quit smoking or vaping?
Cavallazzi: I remind my patients that smoking combustible cigarettes or e-cigarettes is not a failure of character. It is never too late to quit smoking. Most people who quit for good tried a number of times before they were successful. Nicotine is highly addictive and is often listed as one of the most addictive substances out there.
Since nicotine is so addictive, I often offer pharmacological aids such as nicotine replacement – patches, gum and lozenges. The nicotine exposure obtained through these medications is sustained, low dose, designed to be of short term (weeks), not inhaled and not combined with other potentially toxic chemical substances.
There are also other medications that are sometimes offered, including an antidepressant called bupropion, which is often combined with nicotine replacement. And there is a medication called varenicline, which acts on the nicotine receptors.
UofL News: Cigarette smoking has been declining since 1965, which is great news. But e-cigarettes are a relatively new product. What is the most concerning trend in the use of e-cigarettes?
Cavallazzi: Unfortunately, the rates of e-cigarette use are moving in the opposite direction. From 2014 to 2022, current e-cigarette users increased from 3.7% to 6.0% of adults. From 2011 to 2022, the rates went from 0.6% to 4.6% among middle school students and from 1.5% to 10.0% among high school students. This is concerning. These pre-adolescents and adolescents are more vulnerable, and some of the vape companies have marketed their products in ways that attract young users.
Carll: The e-cigarette market is constantly evolving to dodge regulations and enhance appeal, nicotine delivery and the potential for addiction. New untested products and chemical combinations are routinely deployed to users with minimal safety testing. While the long-term risks of current vaping products remain unclear, this real-world uncontrolled experiment continues with little regulation. Our research remains critical to inform users, practitioners and regulators about the overall risks of e-cigarettes and the specific device types, settings and ingredients that pose the greatest harms.
