chemistry

Remote ischemic conditioning

Remote ischemic conditioning is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Remote ischemic conditioning rather than just read about it. In short: Remote ischemic conditioning (RIC) is an experimental medical procedure that aims to reduce the severity of ischaemic injury to an organ such as the heart or the brain, most commonly in the situation of a heart attack or a stroke, or during procedures such as heart surgery when the heart may temporary suffer ischaemia during the operation, by triggering the body's natural protection against tissue injury. Although n…

Key takeaways

Remote ischemic conditioning belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Remote ischemic conditioning to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Remote ischemic conditioning from memory before moving on to harder problems.

Reference excerpt

Remote ischemic conditioning (RIC) is an experimental medical procedure that aims to reduce the severity of ischaemic injury to an organ such as the heart or the brain, most commonly in the situation of a heart attack or a stroke, or during procedures such as heart surgery when the heart may temporary suffer ischaemia during the operation, by triggering the body's natural protection against tissue injury. Although noted to have some benefits in experimental models in animals, this is still an experimental procedure in humans and initial evidence from small studies have not been replicated in larger clinical trials. Successive clinical trials have failed to identify evidence supporting a protective role in humans as of 2015. Two large studies completed in 2023 had re-ignited interest in this technique with positive results. The procedure involves repeated, temporary cessation of blood flow to a limb to create ischemia (lack of oxygen and glucose) in the tissue. This "conditioning" activates the body's natural protective physiology against reperfusion injury and the tissue damage caused by low oxygen levels—a protection present in many mammals. RIC essentially mimics the cardio-protective effects of exercise; in fact, exercise can be considered a form of RIC in which the stimulus is distant from the organ being protected. RIC has been termed "exercise in a device", especially suited for patients who are unable or unwilling to work out.

History The phenomenon of ischemic preconditioning (IPC) was discovered in 1986 by C. E. Murry and colleagues, who observed that repeated, temporary cross-clamping of the left anterior descending artery (LAD) in dogs protected the LAD territory of the heart against a subsequent prolonged ischemic event, reducing infarct size by 75%. This was thought to be a local effect and was termed local ischemic preconditioning. The phenomenon was confirmed by other researchers in dogs, pigs, mice, and rats. In 1993, Karin Przyklenk and colleagues began using the term "remote" when they observed that cross-clamping on the right side of the heart (right circumflex artery) protected the left side of the heart (LAD territory) from ischemia: that is, the protective trigger was remote from the observed effect. Other researchers confirmed this remote effect and found that performing the preconditioning protocol on kidney or gastrointestinal tissue also provided protection to the heart. In 2002, Raj Kharbanda and Andrew Redington, working at the Hospital for Sick Children in Toronto, showed that non-invasively stopping and starting blood flow in the arm provided the same protection as invasive preconditioning of the heart. This adaptation of the RIC protocol significantly improved its safety and applicability, and resulted in a surge of clinical interest in the technique.

Clinical trials More than 10,000 patients worldwide have completed clinical trials involving RIC, and another 20,000 are enrolled in ongoing trials. The first human clinical trial of RIC was conducted by Dr. Redington in pediatric patients undergoing heart surgery at the Hospital for Sick Children. The patients treated with RIC prior to surgery exhibited less heart damage, as measured by the biomarker troponin, as well as less need for supportive drugs. This trial was followed by others measuring the effects of RIC on rates and outcomes of heart attacks, heart failure, stroke, and cardiothoracic intervention.

Heart attacks In multiple randomized controlled trials, remote ischemic conditioning reduced infarct size in ST-elevation myocardial infarction (STEMI) patients when used in the ambulance or emergency department as an adjunct therapy to primary percutaneous coronary intervention (PCI), or when used with thrombolytic drugs. In seven trials comprising 2,372 STEMI patients, infarct size—a measure of damage to the heart—was reduced by 17–30% on average, and the reduction was greatest (~60%) in the largest infarcts. Further analysis of a Danish study (CONDI-1), in which patients were treated in the ambulance, showed that those who received RIC did not show a decline in myocardial salvage index (a measure of a healthy heart) when they experienced a delay in treatment, while the control group experienced a significant decline in salvage index. The RIC treatment therefore resulted, effectively, in an extension of the "golden hour", the period in which medical treatment for heart attacks is most effective. Infarct size is a predictor of future cardiovascular events as well as mortality, and researchers doing long-term follow-up on STEMI patients treated with RIC found that the reduction in heart damage at the time of the heart attack resulted in clinical improvement four years later: MACCE (major adverse cardiovascular and cerebrovascular event) rates were reduced by 47% (13.5% vs. 25.6%, p=0.018). This improvement resulted in mean cumulative cardiovascular medical care costs that were €2,763 lower in the RIC-treated group than in the control group (€12,065 vs. €14,828)—savings of approximately 20%. There are currently two large randomized controlled trials of RIC treatment in STEMI patients ongoing in Europe, both of which will examine the effects of RIC treatment on coronary death and hospitalization for heart failure after one year.

Percutaneous coronary intervention Remote ischemic conditioning significantly reduced heart damage (as measured by troponin elevations) in four randomized controlled trials involving 816 elective (non-emergency) PCI patients. The myocardial damage and troponin elevations seen in elective PCI patients are less than that in emergency STEMI patient, because there is less acute reperfusion injury in elective PCI, and damage instead results from distal embolization and side-branch occlusion. Nevertheless, myocardial damage during elective PCI remains a significant predictor of morbidity and mortality, as patients exhibiting any increase in troponin are at a significantly increased risk of future cardiovascular events. Researchers at Papworth Hospital in Cambridge conducted the first large study of RIC in elective PCI patients (the CRISP study) and found that patients treated with RIC prior to stenting showed a 62% reduction in troponin levels, less chest discomfort, and reduced six-month hospitalization rates. Long-term follow-up of the CRISP study showed that this single RIC treatment resulted in a 35% reduction in six-year MACCE rates.

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Worked examples

Example 1 — a first encounter with Remote ischemic conditioning

Start with the simplest possible case. Write down what Remote ischemic conditioning claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Remote ischemic conditioning before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Remote ischemic conditioning ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Remote ischemic conditioning

In research: Remote ischemic conditioning appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Remote ischemic conditioning in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Remote ischemic conditioning is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cardiac procedures, so understanding it makes those chapters shorter.
In everyday life: Look for Remote ischemic conditioning outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Remote ischemic conditioning in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Remote ischemic conditioning means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Remote ischemic conditioning out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Remote ischemic conditioning in simple terms?

Why does Remote ischemic conditioning matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Remote ischemic conditioning?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Remote ischemic conditioning.