Air pollution linked to deadly heart rhythm disorder

WELLNEWS

Victor Romulo Gallardo Dumaguing, MD

MADRID, Spain – Life-threatening arrhythmias are more common on days with highly polluted air, according to research presented today at Heart Failure 2022, a scientific congress of the European Society of Cardiology (ESC).1 The study was conducted in patients with an implantable cardioverter defibrillator (ICD), enabling the authors to track the occurrence of arrhythmias and delivery of life-saving therapy.
    “Our study suggests that people at high risk of ventricular arrhythmias, such as those with an ICD, should check daily pollution levels,” said study author Dr. Alessia Zanni, now working at Maggiore Hospital, Bologna and previously at Piacenza Hospital, Italy. “When particular matter (PM) 2.5 and PM 10 concentrations are high (above 35 μg/m3 and 50 μg/m3, respectively), it would be sensible to stay indoors as much as possible and wear an N95 mask outside, particularly in areas of heavy traffic. An air purifier can be used at home.”  
    Outdoor air pollution kills an estimated 4.2 million people every year, according to the World Health     Organization.2 Nearly one in five cardiovascular disease deaths are due to dirty air, which was ranked the fourth highest risk factor for mortality after high blood pressure, tobacco use and poor diet.3
    This study investigated the relationship between air pollution and ventricular arrhythmias in Piacenza, Northern Italy. The European Environment Agency graded the city 307 worst out of 323 cities for annual mean PM2.5 concentrations in 2019 and 2020, with a figure of 20.8 μg/m3.4
    “We had observed that emergency room visits for arrhythmias in patients with ICDs tended to cluster on days with particularly high air pollution,” noted Dr. Zanni. “We therefore decided to compare the concentration of air pollutants on days when patients had an arrhythmia versus pollution levels on days without an arrhythmia.”
    The study included 146 consecutive patients who received an ICD between January 2013 and December 2017. Of those, 93 received an ICD because of heart failure after a heart attack while 53 had a genetic or inflammatory heart condition. Just over half (79 patients) had never experienced a ventricular arrhythmia, and 67 patients had previously had a ventricular arrhythmia.
    Data on ventricular arrhythmias (ventricular tachycardia and ventricular fibrillation) were collected remotely from the ICD until study completion at the end of 2017. The researchers also recorded the therapy delivered by the device. This included antitachycardia pacing for ventricular tachycardia (fast heartbeat), which delivers electrical impulses to the heart muscle to restore a normal heart rate and rhythm. The second therapy was an electric shock to reset the heartbeat during ventricular fibrillation.
    Daily levels of PM10, PM2.5, carbon monoxide (CO), nitrogen dioxide (NO2) and ozone (O3) were obtained from Regional Environmental Protection Agency (ARPA) monitoring stations. Patients were assigned exposures based on their home address. The researchers analyzed the association between pollutant concentrations and the occurrence of ventricular arrhythmias.
    A total of 440 ventricular arrhythmias were recorded during the study period, of which 322 were treated with ant tachycardia pacing and 118 were treated with a shock. The researchers found a significant association between PM2.5 levels and ventricular arrhythmias treated with shocks, corresponding to a 1.5% increased risk for each 1 μg/m3 rise in PM2.5. They also found that when PM2.5 concentrations were elevated by 1 μg/m3 for an entire week, compared to average levels, there was a 2.4% higher likelihood of ventricular arrhythmias regardless of the temperature. When PM10 was 1 μg/m3 above average for a week there was a 2.1% raised risk of arrhythmias.
    Dr. Zanni said: “Particulate matter may cause acute inflammation of the heart muscle which could act as a trigger for cardiac arrhythmias. As these toxic particles are emitted from power plants, industries and cars, green projects are needed to protect health, on top of the actions individuals can take to protect themselves.”
She concluded: “These data confirm that environmental pollution is not only a climate emergency but also a public health problem. The study suggests that the survival of patients with heart disease is affected not only by pharmacological therapies and advances in cardiology but also by the air that they breathe. This battle can be won by an alliance between scientific societies and politicians to protect not only the environment but also the health of the human population.

Hypertension

Victor Romulo Gallardo Dumaguing, MD
                                                                                               
May 17 is World Hypertension Day; In the Philippines, May is hypertension awareness month.
With the kind indulgence of our readers, allow the column to do our humble part to raise awareness and promote the prevention, detection and control of hypertension.
    Blood pressure is the force by which blood- 5 liters or 5000 cc in an adult-is delivered to the approximately 75 trillion cells of the body through a network of tubes called blood vessels- arteries carrying oxygen and nutrients which are slowly given to the cells by the capillaries then the veins carry carbon dioxide and metabolic byproducts from the cells back to the heart and their respective excretory organs particularly the lungs and the kidneys.
    Major determinants of blood pressure are cardiac output and total peripheral resistance. Cardiac output is the product of Stroke volume- amount of blood ejected by the heart for every contraction – 60-80 ml -and heart rate- normal is 60-100 beats/min. Thus if stroke volume is 70 and the heart arte is the ideal resting rate of 70, the product is 4900 ml which is close to the normal 5000 ml. Therefore anything that increases cardiac output can raise blood pressure as exemplified by too much salt –sodium chloride- intake. Sodium or natrium exerts greatest osmotic pressure, meaning it attracts water, thus a heavy salty meal can raise the blood pressure by increasing cardiac output to more than 5000ml within the circulatory-blood vessel- system. Emotional outburst whether negative- anger, fear, worry, anxiety- as well as positive – excitement, joy, would make the heart race like a galloping horse, thus raising the blood pressure.
    Total peripheral resistance is the pressure exerted by the volume of blood on the walls of the blood vessels, especially the arteries. In our youth, the arteries are elastic, in other words, flexible enough to expand or distend to accommodate the increase in volume of blood; in short, it’s a balance between vasoconstrictions- less luminal diameter or smaller opening- and vasodilatation.  Ageing process makes the blood vessels less elastic, made worse with lifestyle that revolves around vices like alcohol, smoking and wanton disregard for healthy diet with fat deposits- cholesterol and triglycerides- being deposited on the walls of the blood vessels, thus making the passageway of blood smaller, exerting additional challenge of the heart to contract stronger eventually leading to congestive heart failure.
    Systole’ is heart-contraction-although to be strict about the term, ventricular contractions of the two lower chambers of the heart; atria being the two upper chambers of the heart; diastole’ refers to relaxation of the heart. Thus, with the usual normal blood pressure 120/80, 120 is the systolic pressure or the force by which blood is ejected from the heart, measured in mm mercury; the 80 mm Hg is the pressure when the heart is at its relaxation phase.
    There is a wide variance of blood pressure based on age, gender and other issues like co-morbidities, as exemplified by adult diabetics, which some –not all- doctors prefer a 110/70-80  blood pressure. In so far as hypertension is concerned, the American Heart Association warns that it should not be higher than 140/90 mm Hg, European Society of Cardiology (ESC) puts the ceiling at 135/85mm Hg.
    For sure, there would still be more issues about blood pressure. A stern caveat or a take home message, if you may, hypertension like diabetes is one of so-called “loyal diseases” meaning once they come into your lives, they stay with you forever. Simply put, once diagnosed to be hypertensive, please take the maintenance medicines regularly, to prevent the dreadful complications like heart attack or stroke. The consolation is, with lifestyle modification- dietary and exercise regimen- the blood pressure may stabilize, and yes, the dose of BP medicines may be reduced but NEVER taken off or stopped.