Acute respiratory distress syndrome
Heart Failure In Space: Scientists Calculate Potential Health Threats Facing Future Space Tourists In Microgravity
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Dr Lex van Loon combines mathematical modelling and the use of artificial intelligence to create medical digital twins. Image: Tracey Nearmy/ANU
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[The following is a guest editorial written by Dr Lex van Loon, an assistant professor at the Australian National University and the University of Twente in the Netherlands. He is co-author of a new Frontiers in Physiology article.]
Space exploration has always captivated our imagination, offering the promise of discovering new worlds and pushing the boundaries of human capability. As commercial space travel becomes more accessible, individuals with various underlying health conditions—including heart failure—may soon be among those venturing beyond Earth's atmosphere. This raises critical questions about the impact of space travel on humans with potential underlying health problems. My recent research, 'Computational modeling of heart failure in microgravity transitions,' delves into this issue, offering insights that could shape the future of space travel.
Why study heart failure in space?
The demographic of commercial space travelers is shifting, increasingly including older, wealthy individuals who may not be in optimal health. Unlike professional astronauts, these space tourists typically do not undergo rigorous health screenings or physical training. This shift necessitates a broader consideration of health conditions, such as heart failure, diabetes, and other chronic illnesses, in space mission planning.
Heart failure alone affects over 100 million people globally. Traditionally, space medicine has focused on the effects of microgravity on healthy astronauts. However, the inclusion of non-professional astronauts with preexisting health conditions demands a deeper understanding of how microgravity impacts these individuals. The unique cardiovascular challenges posed by space travel could significantly affect heart failure patients, making this an essential area of study.
Furthermore, heart failure is not a uniform condition and can be broadly categorized into two types. One type involves a weakened heart that cannot pump blood effectively, while the other is characterized by the heart's inability to relax and fill properly. These differences mean that each type of heart failure presents unique challenges and must be studied separately to understand the specific risks and required countermeasures in a microgravity environment.
The challenges of microgravity
In the microgravity environment of space, the human body undergoes significant changes. One of the most notable effects is the redistribution of bodily fluids, causing what is commonly known as 'puffy face bird leg' syndrome. Imagine a person with a swollen, puffy face paired with skinny, almost comically thin legs—like a bird, what's in the name. This fluid shift results in reduced venous pooling in the legs and increased venous pressure in the upper body. For healthy individuals, the cardiovascular system can adapt to these changes, but for heart failure patients, the risks are substantially higher.
Using computational models to simulate space conditions
Given the lack of real-world data on heart failure patients in space, we turned to computational modeling to simulate the effects of microgravity. We used our previously published 21-compartment mathematical model of the cardiovascular system. By tuning the parameters of this model, we were able to predict how heart failure patients might respond during space travel with a high degree of accuracy.
Our simulations revealed that entry into microgravity increases cardiac output in all individuals. However, for heart failure patients, this increase in cardiac output is accompanied by a dangerous rise in left atrial pressure, which can lead to pulmonary edema—a condition where fluid accumulates in the lungs, making it difficult to breathe.
The path forward
Our research underscores the need for comprehensive health screenings and personalized medical plans for space tourists with underlying health conditions. As commercial space travel becomes more accessible, ensuring the safety of all passengers, especially those with chronic health conditions like heart failure, is paramount.
Moreover, our findings highlight the importance of further research into the long-term effects of space travel on cardiovascular health. Future studies should focus on the prolonged exposure to microgravity and the cumulative impact of comorbidities in heart failure patients.
The role of human digital twins
One promising avenue for future research and safety in space travel is the development of human digital twins. A human digital twin is a highly detailed virtual model of an individual's physiological systems. By creating these digital replicas, we can simulate various scenarios and predict how different conditions, such as microgravity, might affect an individual's health. This approach allows for personalized risk assessments and tailored countermeasures.
For heart failure patients, a digital twin could simulate how their specific heart condition would respond to the stresses of space travel. This personalized model could help identify the most effective pre-flight preparations and in-flight interventions, thereby enhancing the safety and well-being of space tourists with heart conditions.
The dream of space travel is closer than ever, but with it comes the responsibility to understand and mitigate the health risks associated with this new frontier. Our computational modeling provides a critical step toward ensuring that space travel is safe for everyone, including those with heart failure. As we continue to push the boundaries of exploration, integrating advanced technologies like human digital twins will be crucial in protecting the health and well-being of all who venture into the final frontier.
JournalFrontiers in Physiology
Method of ResearchComputational simulation/modeling
Subject of ResearchPeople
Article TitleComputational modeling of heart failure in microgravity transitions
Article Publication Date21-Jun-2024
COI StatementThe authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Disclaimer: AAAS and EurekAlert! Are not responsible for the accuracy of news releases posted to EurekAlert! By contributing institutions or for the use of any information through the EurekAlert system.
Mapping The Heart To Prevent Damage Caused By A Heart Attack
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Professor Richard Harvey at the Victor Chang Cardiac Research Institute
view moreCredit: Victor Chang Cardiac Research Institute
Scientists at the Victor Chang Cardiac Research Institute in Australia have produced a first of its kind integrated map of heart cells which unlocks the process of cardiac fibrosis – a major cause of heart failure.
The discovery opens new avenues to develop targeted drugs to prevent scarring damage caused after a heart attack.
During and after a heart attack, the heart's muscles are damaged leading to the formation of scar tissue which lacks the elasticity and contractility of healthy heart muscle. This damage is permanent and can affect the heart's ability to pump blood, eventually leading to heart failure.
Professor Richard Harvey, who led the study alongside the Institute's Dr Ralph Patrick and Dr Vaibhao Janbandhu, says the discovery is a major step forward in understanding cardiac fibrosis – which accompanies virtually all forms of heart disease including the overloading of the heart due to high blood pressure.
"Millions if not billions of dollars have been poured into seeking new drugs to control cardiac fibrosis over the years, but these efforts have largely failed. There is an urgent need to develop novel treatments that could arrest or even reverse cardiac fibrosis, benefiting millions," says Professor Harvey.
"Fibrosis is an essential part of the body's way of healing. But in the heart, if the disease triggers are not resolved, the process can go too far, causing scarring that is incredibly harmful to heart function and a major cause of heart failure.
"For the first time, using revolutionary technology that enables us to analyse gene expression in single cells, we have been able to map out the progressive cell states involved in cardiac fibrosis and how these cells evolve day by day."
The team analysed RNA signatures from 100,000 single cells focusing on those involved in fibrosis, integrating data from several pioneering studies on a variety of heart disease states.
It allowed them to produce an integrated cellular map of a mouse model heart that pinpoints cells and pathways involved in fibrosis.
The study identified resting cells, activated cells, an inflammatory population, a progenitor pool, dividing cells, and specialised cells called myofibroblasts and matrifibrocytes.
It discovered that myofibroblasts – which are believed to be the major drivers of scarring but absent in healthy hearts, start to form three days after a heart attack in a mouse model, before peaking at day five. They are then resolved to a form called matrifibrocytes, which may prevent the scar from resolving.
The study, published in Science Advances, also explored other heart disease models induced heart failure induced by high internal blood pressures as a result of aortic stenosis, or hypertension.
Dr Vaibhao Janbandhu says: "We found a surprising similarity in fibrosis progression in very different types of heart diseases. Myofibroblasts were abundant early on during hypertension and then resolved into matrifibrocytes, just as they are after a heart attack.
"This opens the doors to future therapies that will be able to target specific cell types or processes in different heart diseases. This will hopefully prevent healthy cells from being permanently damaged."
The study used data from both mouse models and human patients. In humans, heart failure may take decades to evolve, so the exact cell types and the timing of processes in human patients need to be explored in greater detail.
Dr Janbandhu adds: "Persistent high blood pressure can have devastating consequences, but it is treatable, highlighting the need to monitor for high blood pressure and get it under control quickly."
The team has also created the 'CardiacFibroAtlas', a resource web tool for researchers worldwide. It allows users to visualize and analyse how genes behave in heart attacks and related health problems. Available at https://cardiacfibroatlas.Victorchang.Edu.Au/
Method of ResearchExperimental study
Subject of ResearchAnimal tissue samples
Article TitleIntegration mapping of cardiac fibroblast single-cell transcriptomes elucidates cellular principles of fibrosis in diverse pathologies
Article Publication Date21-Jun-2024
COI StatementNo conflict of interests.
Disclaimer: AAAS and EurekAlert! Are not responsible for the accuracy of news releases posted to EurekAlert! By contributing institutions or for the use of any information through the EurekAlert system.
Heart Failure And The Biventricular Pacemaker
In the normal heart, the heart's lower chambers (ventricles) pump in sync with the heart's upper chambers (atria).
When a person has heart failure, often the right and left ventricles do not pump synchronously. And when the heart's contractions become out of sync, the left ventricle may not be able to pump enough blood to the body.
This eventually leads to an increase in heart failure symptoms, such as shortness of breath, dry cough, swelling in the ankles or legs, weight gain, increased urination, fatigue, or rapid or irregular heartbeat.
Cardiac resynchronization therapy (CRT), also called biventricular pacing, uses a special kind of pacemaker, called a biventricular pacemaker, designed to help the ventricles contract more normally.
It keeps the right and left ventricles pumping in sync by sending small electrical impulses through the leads.
This therapy has been shown to improve the symptoms of heart failure and overall quality of life in certain patients with significant symptoms that aren't controlled with medication.
Leads are tiny wires implanted through a vein into the right ventricle and into the coronary sinus vein to pace or regulate the left ventricle. Usually (but not always), a lead is also implanted into the right atrium. This helps the heart beat in a more balanced way.
Traditional pacemakers are used to treat slow heart rhythms. Pacemakers regulate the right atrium and right ventricle to maintain a good heart rate and keep the atrium and ventricle working together. This is called AV synchrony. Biventricular pacemakers add a third lead to help the left ventricle have a more efficient contraction.
Biventricular pacemakers improve the symptoms of heart failure in about 50% of people that have been treated with medications but still have significant heart failure symptoms. Therefore, to be eligible for the biventricular pacemaker, heart failure patients must:
In addition, the heart failure patient may or may not need this type of pacemaker to treat slow heart rhythms and may or may not need an internal defibrillator (implantable cardioverter defibrillator, or ICD), which is designed to treat people at risk for sudden cardiac death or cardiac arrests.
People with heart failure who have poor ejection fractions (a measurement that shows how well the heart pumps with each beat) are at risk for fast irregular heart rhythms -- some of which can be life-threatening -- called arrhythmias. Currently, doctors use an ICD to prevent these dangerous rhythms. The device works by detecting such a rhythm and shocking the heart back to normal.
These devices can combine biventricular pacing with anti-tachycardia (fast heart rate) pacing and internal defibrillators (ICDs) to deliver treatment as needed. Current studies are showing that resynchronization may even lessen the amount of arrhythmia that occurs, decreasing the times the ICD needs to shock the heart. These devices are helping heart failure patients live longer and improving their quality of life.
Ask your doctor what medications you are allowed to take before your pacemaker is implanted. Your doctor may ask you to stop certain drugs several days before your procedure. If you have diabetes, ask your doctor how you should adjust your diabetic medications.
Do not eat or drink anything after midnight the night before the procedure. If you must take medications, drink only small sips of water to help you swallow your pills.
When you come to the hospital, wear comfortable clothes. You will change into a hospital gown for the procedure. Leave all jewelry and valuables at home.
Pacemakers can be implanted two ways:
Inside the Heart (Endocardial, Transvenous approach): This is the most common technique used. A lead is placed into a vein (usually under your collarbone), and then guided to your heart. The tip of the lead attaches to your heart muscle. The other end of the lead is attached to the pulse generator, which is placed under the skin in your upper chest. This technique is done under local anesthesia (you will not be asleep).
Outside the Heart (Epicardial approach): Your chest will be opened and the lead tip is attached to the outside of the heart. The other end of the lead is attached to the pulse generator, which is placed under the skin in your abdomen. This technique is done under general anesthesia (you will be asleep) by a surgeon. This is typically performed in conjunction with open heart surgery being performed for another reason.
Your doctor will decide which approach is best for you, although almost all patients receive the transvenous approach.
Hospital stay: After the pacemaker implant, you will be admitted to the hospital overnight. The nurses will monitor your heart rate and rhythm. You will also have a monitor (a small recorder that is attached to your chest by small electrode patches). It will record your heart rhythm while you are in the hospital. This is another way to check proper pacemaker function. The morning after your implant, you will have a chest X-ray to check your lungs and the position of your pacemaker and leads. Your pacemaker will be checked to make sure it's working properly. The results of the test will be reported to your doctor.
Final pacemaker check: For your final pacemaker check, you will sit in a reclining chair. A small machine known as a programmer is used to check your pacemaker. It has a wand that is placed directly over the device. This machine allows the technician to read your pacemaker settings and make changes during testing. With these changes, the function of the pacemaker and leads can be evaluated. You may feel your heart beating faster or slower. This is normal; however, report all symptoms to the technician. Results of the pacemaker check are discussed with your doctor who will then determine your pacemaker settings.
After your pacemaker check, an echocardiogram may be done. The technician nurse will be there during your echo and will check your pacemaker settings. The echocardiogram will be repeated with each setting to evaluate heart function. The pacemaker will keep the settings that were associated with your best heart function.
Usually, you will be able to go home the day after your pacemaker is implanted. Your doctor will discuss the results of the procedure and answer any questions you may have. A doctor or nurse will go over specific instructions for your care at home. Please ask a responsible adult to drive you home, as the medications you received may cause drowsiness, making it unsafe for you to drive or operate heavy machinery.
Keep the area where the pacemaker was inserted clean and dry. After about five days, you may take a shower. Look at your wound daily to make sure it is healing. Call your doctor if you notice:
After your pacemaker is implanted, you may move your arm; you don't have to restrict its motion during normal daily activities. Avoid extreme pulling or lifting motions (such as placing your arm over your head without bending at the elbow). Activities such as golf, tennis, and swimming should be avoided for six weeks from when the pacemaker was implanted. Microwave ovens, electric blankets, and heating pads may be used. Cellular phones should be used on the side opposite your pacemaker. Ask your doctor or nurse for more specific information regarding what types of equipment may interfere with your pacemaker.
Pacemaker Identification: You will receive a temporary ID card that tells you what type of pacemaker and leads you have, the date of implant and the doctor who implanted it. In about three months following implantation, you will receive a permanent card from the company. It is important that you CARRY THIS CARD AT ALL TIMES in case you need medical attention at another hospital.
Your medical team will arrange for a complete pacemaker check after your pacemaker is implanted. This check is very important because adjustments will be made that can prolong the life of your pacemaker. After that, your pacemaker should be checked every six months using a telephone transmitter to evaluate battery function. The nurse will explain how to check your pacemaker using the telephone transmitter. When the battery gets low, you will need to replace your pacemaker.
A follow-up pacemaker check is scheduled every three to six months. This check differs from the telephone check because the leads are also tested. Leads cannot be checked thoroughly over the telephone.
Here is an outline of a typical pacemaker follow-up schedule:
Pacemakers usually last 6 to 10 years. Biventricular pacemakers that are combined with an ICD do not tend to last as long.
After getting a pacemaker, you will need to follow-up with the doctor and nurses in a pacemaker clinic and through phone check-ups. This will allow them to monitor your pacemaker's function and anticipate when it will need to be changed. In addition, the pacemaker may be programmed to beep when the battery is low. Your doctor will demonstrate this beep for you.
Resynchronization therapy is only one part of a comprehensive heart failure management program. Device and/or surgical therapy, when combined with taking medications, following a low-sodium diet, making lifestyle changes, and following up with a heart failure specialist, will help you decrease symptoms and live a longer, more active life. Your doctor will help determine what treatment options are best for you.
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