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People may feel a flip-flop in their chest when they're under stress, haven't slept well or even during normal activity. They may say, "I felt my heart stop for a second." But in most cases, that heart-stopping feeling is actually an extra heartbeat, called a premature ventricular contraction (PVC).

They're very common. Some people feel them, but others don't."

Dr. Sarah Hussain, cardiac electrophysiologist with Penn State Heart and Vascular Institute

PVCs most often originate in the bottom chambers of the heart. "A PVC is a wider looking heartbeat," said Barbara Bentz, a certified registered nurse practitioner with the Heart and Vascular Institute. "That extra beat is almost always followed by a pause, which occurs when the heart resets back to its normal beat."

For people who feel PVCs, they can seem frightening. "They are not always dangerous," Hussain said.

Causes of PVCs can vary. They may occur in high-adrenaline situations, triggered by stress or anxiety. Others may be side effects from certain medications. Sometimes electrolyte imbalances can cause PVCs. So can too much caffeine or alcohol.

PVCs can occur at any age, young or old. The causes of PVCs often varies depending on the age of the patient.

PVCs become more of a concern if they happen frequently. "If more than 10% to 15% of a person's heartbeats in 24 hours are PVCs, that's excessive," Bentz said. The more PVCs occur, the more they can potentially cause a condition called cardiomyopathy (a weakened heart muscle).

People who have experienced a prior heart attack-;or those already diagnosed with cardiomyopathy-;should also take PVCs seriously. So too should people who experience symptoms, which can include chest pain and shortness of breath, in addition to palpitations or skipped heartbeats.

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The first step in diagnosing PVCs-;and learning whether they need treatment-;is an electrocardiogram (ECG), performed in a primary care doctor's office. A physician may recommend a wearable cardiac (Holter) monitor that will record a person's heartbeats over a 24-hour period. "That will quantify how many PVCs someone is having and the frequency of their PVCs," Hussain said.

In some cases, doctors may order an exercise stress test to see whether PVCs become worse with exertion.

Treatment for PVCs depends upon their cause. "If people only experience them when they have a large cup of coffee, then reducing caffeine intake is likely the answer," Bentz says. Other lifestyle changes may include reducing alcohol or energy drink consumption.

For people experiencing frequent PVCs, medications such as beta blockers, which slow heart rate, or calcium channel blockers, which relax the heart, may reduce the number of extra beats. Antiarrhythmic medications may also be used. If medication isn't effective or well tolerated because of side effects, doctors may recommend a minimally invasive procedure called cardiac ablation. It cauterizes the spot in the bottom chamber of the heart that causes the PVCs.

While most PVCs are harmless, people who experience any irregular heartbeat should call their doctor's office. "It may be PVCs or another type of arrhythmia," Hussain says. "So always ask to be evaluated and get an ECG."

Source:

Penn State Health

A breakthrough medical technology can save the lives of children with heart defects. Scientists have developed the first-ever heart valve that grows with the child, reducing the need for risky heart surgeries in the future.

Children with congenital heart disease who need valve replacement often undergo multiple surgeries because the valve cannot grow as the child's heart grows. They need multiple heart surgeries to change the heart valve to accommodate the growing size of the heart. However, these surgeries are risky and pose a threat to the child's health.

To solve this problem, a team of scientists from Boston Children's Hospital developed a prosthetic valve that mimics the geometry of the human venous valve. Composed of polymeric leaflets attached to a stainless-steel stent, the valve can be expanded by a minimally invasive balloon catheter procedure, reducing invasive open-heart surgeries.

The doctors can use keyhole surgery to insert a rubber tube attached to a deflated balloon in the valve. They can inflate it depending on the child's heart size.

The valve replacement expanding to accommodate different lengths in implanted sheep. This material relates to a paper that appeared in the Feb. 19, 2020, issue of Science Translational Medicine, published by AAAS. The paper, by S.C. Hofferberth at Boston Children's Hospital in Boston, MA; and colleagues was titled, "A geometrically adaptable heart valve replacement." Image Credit: S.C. Hofferberth et al., Science Translational Medicine (2020)

Multiple heart surgeries

Congenital heart valve disease is life-threatening, and children with this condition may need valve replacement early in their lives. However, children grow, and the artificial heart valve may not be able to accommodate the heart's increasing size.

Many children with this condition face high-risk and multiple open-heart surgeries to remove the valves and replace then with bigger ones.

The scientists used computational modeling to predict how their valve replacement expanded to deal with the stress of blood flow. This material relates to a paper that appeared in the Feb. 19, 2020, issue of Science Translational Medicine, published by AAAS. The paper, by S.C. Hofferberth at Boston Children's Hospital in Boston, MA; and colleagues was titled, "A geometrically adaptable heart valve replacement." Credit: S.C. Hofferberth et al., Science Translational Medicine (2020)

For the first time, the new valve, a biomimetic prosthetic valve, adapts to accommodate growth and structural asymmetries within the heart. In previous heart valve models, they contain three leaflet-like flaps providing a one-way inlet or outlet for blood flow. However, in the new heart valve, it only has two flaps, with a geometry designed to maintain closure, and a one-way flow even when the veins expand in diameter.

"Veins carry approximately 70 percent of our blood volume. The vein dimensions can change dramatically depending on body position, yet the valves must remain functional. We mimicked the geometric profile of the human venous valve to design a bi-leaflet valve of programmed dimensions that is adaptable to growth without loss of one-way flow control," Dr.  Sophie C. Hofferberth, a surgical resident at Brigham and Women's Hospital and lead researcher at Boston Children's Hospital, said.

New artificial heart valve on the way

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The new heart valve has been tested in large animal models, computer simulations, and benchtop studies, demonstrating that it works across a broad range of sizes. What is more, it retains functionality and efficacy when it is expanded through a balloon catheter procedure.

The team tested the prosthetic heart valve in growing young lambs. When implanted on the animals, it exhibited good performance without the blockage of blood flow. In another test in other lambs, the valves stayed functional for ten weeks without causing inflammation or injury to the heart tissues.

Though the study requires human testing and longer-follow up times, there is more work needed to validate the design. If it passes through rigorous testing, it can help more than 1.35 million children across the globe who were born with a congenital heart valve disorder.

The researchers also found that the new prosthetic valve promotes favorable blood flow through the valve, reducing the risk for blood clot formation, which is often observed in existing valve replacement devices. With the invasive heart valve device, there are fewer complications that may endanger the life of the child.

The study was published in the journal Science Translational Medicine.

What is congenital heart valve disease?

The heart pumps blood throughout the body throughout the day, and it contains valves that are responsible for keeping the blood from flowing backward. As a result, the blood flow is controlled, and the oxygenated and non-oxygenated blood will not mix.

A congenital heart valve disease happens if one or more of the valves in the heart do not work well, leading to problems such as regurgitation, stenosis, and atresia. Usually, this occurs when a heart's valves do not develop before birth, causing a defect that keeps the valve from closing completely.

Regurgitations happen when the blood backflows because the valve does not close tightly or adequately. The most common cause of blood backflow is a valve prolapse.

Stenosis happens when the flaps become thick, stiff, or fuse, resulting in the inability of the valve to open fully. Stenosis leads to blockage of blood flow. Atresia pertains to a condition when the valve does not have an opening for the blood to pass through.

All these conditions lead to a wide range of heart problems and can endanger the life of the child. Over time, these problems can strain the heart because it works double-time to compensate for the valve defect. It can cause serious problems such as aortic aneurysm, dilated cardiomyopathy, and heart failure.

Source:

National Heart, Lung, and Blood Institute. (2020). Heart Valve Disease. https://www.nhlbi.nih.gov/health-topics/heart-valve-disease.

Journal reference:

Hofferberth, S., Saeed, M., Tomholt, Fernandes, M., Payne, C., Price, K., Marx, G., Esch, J., Brown, J. et al. (2020). A geometrically adaptable heart valve replacement. Science Translational Medicine. https://stm.sciencemag.org/content/12/531/eaay4006?rss=1.

Researchers at the University of California, Riverside, have completed a cross-sectional human study that compares biomarkers and metal concentrations in the urine of e-cigarette users, nonsmokers, and cigarette smokers.

They found that the biomarkers, which reflect exposure, effect, and potential harm, are both elevated in e-cigarette users compared to the other groups and linked to metal exposure and oxidative DNA damage.

Our study found e-cigarette users are exposed to increased concentrations of potentially harmful levels of metals — especially zinc — that are correlated to elevated oxidative DNA damage.”

Prue Talbot, professor of cell biology, University of California, Riverside

Zinc, a dietary nutrient, plays key roles in growth, immune function, and wound healing. Too little of this essential trace element can cause death; too much of it can cause disease. Its deficiency, as well as its excess, cause cellular oxidative stress, which, if unchecked, can lead to diseases such as atherosclerosis, coronary heart disease, pulmonary fibrosis, acute lymphoblastic leukemia, and lung cancer.

Electronic cigarettes consist of a battery, atomizing unit, and refill fluid. Metals in e-cigarette aerosols come mainly from the metal components in the atomizer– nichrome wire, tin solder joints, brass clamps, insulating sheaths, and wicks — as well as the e-fluids that the atomizers heat.

The study, which appears in BMJ Open Respiratory Research, marks the first time researchers have examined and quantified urinary biomarkers of effect and potential harm in relation to metals in e-cigarette users.

A biomarker is a quantifiable characteristic of a biological process. Biomarkers allow researchers and physicians to measure a biological or chemical substance that is indicative of a person’s physiological state. Previous e-cigarette studies with humans have examined biomarkers of exposure — for example, nicotine or nicotine metabolites — but none have studied biomarkers of potential harm or shown how this harm correlates with metal exposure.

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The biomarkers studied by the UC Riverside researchers were 8-hydroxydeoxyguanosine (8-OHdG), a biomarker of oxidative DNA damage; 8-isoprostane, an indicator of the oxidative degradation of lipids; and metallothionein, a metal response protein. All three biomarkers were significantly elevated in e-cigarette users compared to the concentrations in cigarette smokers.

“Our findings reaffirm that e-cigarette use is not harm free,” said Shane Sakamaki-Ching, a graduate student in the Cell, Molecular and Developmental Biology Graduate Program and the research paper’s first author. “Indeed, prolonged use may lead to disease progression.”

The researchers advise physicians to exercise caution when recommending e-cigarettes to their patients. Electronic cigarette aerosols contain potentially harmful chemicals, cytotoxic flavor chemicals, metals, ultrafine particles, and reaction products. E-cigarette use has been linked to adverse health effects such as respiratory diseases, increased risk for cardiovascular disease, and impaired wound healing following surgery.

“Pregnant women, especially, should not be encouraged to use e-cigarettes,” Talbot said. “Excess of zinc in their bodies can lead to nausea and diarrhea. Given the recent deaths and pulmonary illnesses related to e-cigarette usage, everyone should be made aware of the potential health risks linked to e-cigarette usage.”

Source:

University of California – Riverside

Journal reference:

Sakamaki-Ching, S., et al. (2020) Correlation between biomarkers of exposure, effect and potential harm in the urine of electronic cigarette users. BMJ Open Respiratory Research. doi.org/10.1136/bmjresp-2019-000452.