The document discusses various techniques for assessing myocardial viability, including stress echocardiography, single photon emission computed tomography (SPECT), positron emission tomography (PET), and cardiac magnetic resonance imaging (MRI). Stress echocardiography evaluates contractile reserve through techniques like dobutamine stress echocardiography. SPECT assesses viability by detecting thallium or technetium uptake, which relies on intact cell membranes. PET detects FDG uptake indicating active glucose metabolism. MRI evaluates viability through detection of late gadolinium enhancement, indicating scar tissue, and can also assess contractile reserve with stress MRI. A combined approach utilizing multiple techniques can provide complementary information on viability.
Various coronary physiological measurements can be made in the cardiac catheterization laboratory using sensor-tipped guidewires; they include the measurement of poststenotic absolute coronary flow reserve, the relative coronary flow reserve, and the pressure-derived fractional flow reserve of the myocardium. Ambiguity regarding abnormal microcirculation has been reduced or eliminated with measurements of relative coronary flow reserve and fractional flow reserve. The role of microvascular flow impairment can be separately determined with coronary flow velocity reserve measurements. In addition to lesion assessment before and after intervention, emerging applications of coronary physiology include the determination of physiological responses to new pharmacological agents, such as glycoprotein IIb/IIIa blockers, in patients with acute myocardial infarction. Measurements of coronary physiology in the catheterization laboratory provide objective data that complement angiography for clinical decision-making
preop TEE assessment of atrial septal defect is very important for making decision for device closure, properly assessed adequate rims of ASD will reduce risk of device embolization to almost nil.
Our concepts of heart disease are based on the enormous reservoir of physiologic and anatomic knowledge derived from the past 70 years' of experience in the cardiac catheterization laboratory.
As Andre Cournand remarked in his Nobel lecture of December 11, 1956, the cardiac catheter was the key in the lock.
By turning this key, Cournand and his colleagues led us into a new era in the understanding of normal and disordered cardiac function in huma
rotablation is procedure used in complex pci with heavily calcified lesion for adequate expansion of stent.if used in indicated case and well aware of contraindication is necessary for achieving good results.
Intracoronary Imaging – when to use, how to use and how to interpret the imagesEuro CTO Club
Intracoronary Imaging – when to use, how to use and how to
interpret the images
Javier Escaned, Spain
The Experts “Live” Workshop 2017
Saturday, September 16th, 2017
Various coronary physiological measurements can be made in the cardiac catheterization laboratory using sensor-tipped guidewires; they include the measurement of poststenotic absolute coronary flow reserve, the relative coronary flow reserve, and the pressure-derived fractional flow reserve of the myocardium. Ambiguity regarding abnormal microcirculation has been reduced or eliminated with measurements of relative coronary flow reserve and fractional flow reserve. The role of microvascular flow impairment can be separately determined with coronary flow velocity reserve measurements. In addition to lesion assessment before and after intervention, emerging applications of coronary physiology include the determination of physiological responses to new pharmacological agents, such as glycoprotein IIb/IIIa blockers, in patients with acute myocardial infarction. Measurements of coronary physiology in the catheterization laboratory provide objective data that complement angiography for clinical decision-making
preop TEE assessment of atrial septal defect is very important for making decision for device closure, properly assessed adequate rims of ASD will reduce risk of device embolization to almost nil.
Our concepts of heart disease are based on the enormous reservoir of physiologic and anatomic knowledge derived from the past 70 years' of experience in the cardiac catheterization laboratory.
As Andre Cournand remarked in his Nobel lecture of December 11, 1956, the cardiac catheter was the key in the lock.
By turning this key, Cournand and his colleagues led us into a new era in the understanding of normal and disordered cardiac function in huma
rotablation is procedure used in complex pci with heavily calcified lesion for adequate expansion of stent.if used in indicated case and well aware of contraindication is necessary for achieving good results.
Intracoronary Imaging – when to use, how to use and how to interpret the imagesEuro CTO Club
Intracoronary Imaging – when to use, how to use and how to
interpret the images
Javier Escaned, Spain
The Experts “Live” Workshop 2017
Saturday, September 16th, 2017
Left ventricular (LV) dysfunction remains one of the
best prognostic determinants of survival in patients
with coronary artery disease (CAD)
⚫ It was originally thought that dysfunctional
myocardium after an infarction was irreversibly
damaged
⚫ However, it was later recognized that some of the
involved tissue remained viable and contractility may
be restored with revascularization
Based on the principle that the distal coronary pressure measured during vasodilation is directly proportional to maximum vasodilated perfusion.
FFR is defined as the ratio of maximum blood flow in a stenotic artery to maximum blood flow in the same artery if there were no stenosis.
FFR is simply calculated as a ratio of mean pressure distal to a stenosis (Pd) to the mean pressure proximal stenosis, that is the mean pressure in the aorta (Pa), during maximal hyperaemia.
New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
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The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
2. Pathophysiology of Myocardial
Ischemia and Viability
• Imbalance between oxygen supply and demand results in
myocardial ischemia.
• If the imbalance is transient (i.e., triggered by exertion), it
represents reversible ischemia.
• However, if supply-demand imbalance is prolonged, high-
energy phosphates are depleted, and regional contractile
function progressively deteriorates.
• If the supply-demand balance is sufficiently prolonged, cell
membrane rupture with cell death follows.
Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 16 page 291 -294
3.
4. • The myocardium has several mechanisms of acute and chronic
adaptation to a temporary or sustained reduction in coronary
blood flow , known as
• stunning,
• hibernation, and
• ischemic preconditioning .
• These responses to ischemia preserve sufficient energy to
protect the structural and functional integrity of the cardiac
myocyte.
Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 16 page 291 -294
5. Stunned myocardium
• is most often observed after a transient period of ischemia
followed by reperfusion (depressed function at rest but
preserved perfusion).
• Regional myocardial function remains depressed for up to 6 hours
after resolution of ischemia following a 15-minute occlusion in
the absence of tissue necrosis
• The ischemic episodes can be single or multiple, brief or
prolonged, but never severe enough to result in injury.
• This state is typically observed soon after coronary occlusion
and reperfusion in the setting of acute MI.
Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 16 page 291 -294
6. Hibernating myocardium
• refers to adaptive responses of the myocardium to repetitive
episodes of ischemia resulting in myocardial hypoperfusion at
rest (depressed function and perfusion at rest).
• In clinical practice, it is likely that the adaptive responses of
hibernation and stunning coexist.
• In stunned and hibernating myocardium, myocardial function
is depressed at rest, but myocytes remain viable.
Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 16 page 291 -294
7.
8.
9.
10. Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 57 page 1092
11. Myocardial Viability
• Requirements for cellular viability include
• (1) sufficient myocardial blood flow,
• (2) cell membrane integrity, and
• (3) preserved metabolic activity.
• Myocardial blood flow must be adequate to deliver substrate
to the myocyte for metabolic processes and to remove the
end products of metabolism.
Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 16 page 291 -294
12. • If Myocardial blood flow is severely reduced,
• metabolites accumulate,
• causing inhibition of the enzymes of the metabolic pathway,
• depletion of high-energy phosphates,
• cell membrane disruption, and
• cell death.
• Thus, with severe reduction in blood flow, perfusion tracers alone
provide information about myocardial viability or absence of
viability.
Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 16 page 291 -294
13. • However, in regions in which the Myocardial blood flow
reduction is less severe,
• perfusion information alone may be an insufficient signal to
• identify clinically relevant viability, and additional data, such as
metabolic indices, may be important.
Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 16 page 291 -294
14. • Because cell membrane integrity, another requisite for cell
survival, is dependent on preserved intracellular metabolic
activity to generate high-energy phosphates,
• tracers that reflect cation flux (e.g., 201Tl),
• electrochemical gradients (sestamibi or tetrofosmin), or
• metabolic processes (FDG)
• provide insight into myocardial viability
Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 16 page 291 -294
15.
16. MajorMyocardialFuels and Energeticsin
Normaland IschemicMyocardium
• High-energy phosphates, such as adenosine triphosphate (ATP),
provide the fuel that powers the myocyte contractile proteins .
• ATP is generated in the myocardium by two different but integrated
metabolic processes: oxidative phosphorylation and glycolysis.
• Fatty acids, glucose, and lactate are the major sources of energy in
the heart, and depending on the arterial concentration of each and
the physiologic condition, any one of these three can be the
principal substrate.
• Increased uptake and use of one substrate will lead to a decreased
contribution by the others.
Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 16 page 291 -294
17. • In the fasting state,
• long-chain free fatty acids are the preferred source of energy in
the heart,
• with glucose accounting for only 15% to 20% of the total energy
supply.
• When the oxygen supply is normal, high levels of ATP and
tissue citrate formed by breakdown of fatty acids suppress the
oxidation of glucose.
• When the oxygen supply is decreased, ATP and citrate levels
fall, and the rate of glycolysis is accelerated.
Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 16 page 291 -294
18. • Anaerobic glycolysis can be maintained only if lactate and hydrogen
ion (the byproducts of glycolysis) are removed and do not
accumulate.
• In the setting of severe hypoperfusion, these end products of the
glycolytic pathway accumulate,
• causing inhibition of the glycolytic enzymes and depletion of high-
energy phosphates,
• resulting in cell membrane disruption and cell death.
• Thus, even to maintain anaerobic glycolysis, minimally sufficient
blood flow is necessary.
21. • Different non-invasive methods that assess viability tests
different facets which indicate that the “cell is alive”.
• Stress echo - contractile reserve
• SPECT - Thallium and technetium uptake indicates intact cell
membrane (thallium is a potassium analogs that relies on the
Na/K ATPase for uptake, technetium uptake relies on intact
mitochondrial membrane potential)
• PET - FDG-18 uptake indicates active glucose metabolism.
• MRI - delayed enhancement/ hyperenhancement-non viable
scarred tissue.
• stress MRI -tests contractile reserve.
22. 1 Stress Echocardiography
• there are five techniques employed;
• dobutamine stress,
• myocardial contrast,
• 2d gray scale wall motion scoring,
• tissue doppler
• adenosine speckle tracking stress echocardiography.
• Resting echocardiography highlights diastolic wall thickness of
at least 5 mm as a marker of viable myocardium.
• the most commonly used criterion to identify viable
myocardium is by detection of contractile reserve.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
23. stress echocardiography
• this is achieved by stress echocardiography using dobutamine,
Adenosine or dipyridamole.
• An infusion of low-dose dobutamine (5–10 mg/ kg/min) is
administered which results in increased contractile function of
viable segments whereas nonviable ones do not show such
response.
• Dobutamine infusion starts at 5 μg/kg per minute for 3
minutes and increases to 10 μg/kg per minute for an
additional 3 minutes.
• Myocardial viability can also be detected by using the biphasic
response
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
24. • With dobutamine infusion, it may demonstrate a
• (1) a lack of increase in baseline contractility suggesting myocardial
necrosis;
• (2) an increase in myocardial contractility suggesting myocardial
stunning or hibernation or
• (3) BIPHASIC RESPONSE at
• lower doses(5–10mg/kg/min)--an improvement in contractile
performance
• at higher doses (>15mg/kg/min)--Contractility regresses as the
metabolic demand stimulated overwhelms the tissue‘s capacity to
respond
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
25.
26. contrast echocardiography
• using intravenous micro-bubble contrast, contrast
echocardiography is able to demonstrate viability qualitatively.
• these micro-bubbles are inert gases and stay in the vascular
space and behave like red blood cells in terms of rheology.
• segments that have normal or patchy perfusion are classified
as being viable in contrast to those with no perfusion who are
taken as non-viable.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
27. • Myocardial contrast enhancement depends on an intact
microcirculation.
• Left ventricular opacification (LVO) obtained with microbubbles
improves the definition of the LV border.
• This provides better quantitation of LV volume by the Simpson
method.
• The correlation between LV volume measured with cardiac magnetic
resonance (CMR) and that measured with echocardiography is
better with the use of LVO.
• Regional wall motion analysis can also be better with LVO.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
28.
29. doppler echocardiography
• uses optimum increase in coronary flow reserve (CFR) as an
additional marker of viability.
• the underlying mechanism behind that is the increased
myocardial metabolic demand with stress, which causes
dilatation of the coronary vessels.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
30. adenosine speckle tracking
• Additional information on myocardial viability can be obtained
from adenosine speckle tracking based myocardial strain
imaging.
• usually at rest, there is no significant difference between the
viable and nonviable myocardium strain.
• with adenosine stress, viable segments increase their
longitudinal strain in contrast to non-viable ones which remain
unchanged
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
31. Low Dose Dobutamine Stress
Echocardiography (LDDE)
• the most recent meta-analysis by schinkel AF et al (2007), of
33 studies (1121 patients);
• cumulative sensitivity and specificity of 81% and 78%
respectively,
• with a positive predictive value (ppV) and negative predictive
value (NpV) of 75% and 83% respectively, (p < 0.05).
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
32. Limitation and advantages
• The main limitations of echocardiography include;
• operator dependence, both in data acquisition, and interpretation,
however, this could easily be overcome by good training and
experience.
• Adequate acoustic window acquisition is another potential
limitation but has greatly improved by using contrast agents.
• The main advantages of stress echocardiography include;
• good validity,
• wide availability,
• cost effectiveness,
• lack of ionizing radiation, and
• being friendly with implanted devices.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
33. Prognostic value
• The VIAMI-trial (2012), Viability-Guided Angioplasty After Acute Myocardial
Infarction was the first randomized control trial
• investigating a viability-guided invasive approach in
• 261 patients recruited
• at least 48 hours after an acute MI who then underwent LDDE for the
• detection of viability within 72 hours of MI.
• Those with a viable myocardium were randomized to an invasive or conservative
treatment.
• The primary endpoint was the composite of death from any cause, recurrent MI
and unstable angina at 1-year follow-up.
• An invasive approach in patients with a high viability score had a substantial
reduction in ischemic events.
• The VIAMI-trial supports the concept that viability determines prognosis.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
34. 2 SPECT
• The main technique involve the administration of a radioactive tracer
such as thallium-201 or Technetium Tc-99m, with Tc-99m sestamibi
being the most widely used in clinical practice.
• The most commonly used criterion to identify viable myocardium is the
percentage tracer uptake by the dysfunctional segments,
• where a tracer activity of >50% and
• redistribution of >10% are
• used as markers of viability as a consequence of preserved membrane
integrity (detected by thallium SPECT).
• A tracer activity of >50% and improvement in tracer uptake
• after nitrates administration is also taken as a markers of viability, as a
consequence of preserved mitochondrial function (detected by technetium
SPECT).
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
35. Principles of Assessing Myocardial
Viability by Radionuclide Techniques
• Quantitative analysis of tracer uptake correlates directly with the
magnitude of preservation of tissue viability, and
• For a dysfunctional segment or territory, the probability of functional
recovery after revascularization is related to the magnitude of tracer
uptake,
• representing the degree of preserved myocardial viability (extent of
hibernation or stunning) within that territory.
• A dysfunctional territory with normal or only mildly reduced tracer
uptake thus has a high likelihood of improved function after
revascularization.
• By contrast, a territory with a severe reduction in tracer uptake would
represent predominant infarction, and the likelihood of improved
function after revascularization would be low.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
36. Relation between tracer uptake in a dysfunctional territory and the
subsequent probability of functional recovery after revascularization.
Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 16 page 291 -294
37. Imaging Protocols for Assessment of
Myocardial Viability
• Thallium-201.
• The presence of 201Tl after redistribution implies preserved
myocyte cellular viability.
• Because the absence of 201Tl uptake on the redistribution images is
not a sufficient sign of the absence of regional viability
• After 201Tl reinjection, approximately 50% of regions with fixed
defects on stress-redistribution imaging show significant
enhancement of 201Tl uptake, predictive of improvement in
regional LV function.
• The presence of a severe 201Tl defect after reinjection identifies
areas with a very low probability of improvement in function.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
38. Standard SPECT imaging display.
A, The short-axis images
represent a portion of the
anterior, lateral, inferior, and
septal walls.
B, Vertical long-axis images
represent the anterior wall,
apex, and inferior wall.
C, Horizontal long-axis images
represent the septum, apex, and
lateral walls.
42. • Various protocols have been developed to optimise the
information obtained from thallium-201 imaging such as;
• stress redistribution imaging,
• late redistribution imaging,
• thallium-201 re-injection and
• rest-redistribution imaging
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
43. 201Tl stress redistribution
• The uptake of 201Tl is an energy-dependent process requiring
intact cell membrane integrity, and the presence of 201Tl
implies preserved myocyte cellular viability.
• Imaging is done-
• immediately following stress, with either exercise or
pharmacologically induced coronary hyperemia with
dipyridamole or adenosine, and
• after 3–4 hr redistribution of Tl-201
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
44. INTERPRETATION
• Defects on post-stress images, may fill in by the time the rest-
redistribution images are acquired, indicating viability.
• A defect that persists and appears again on the 3–4 hr images
• (i.e., a fixed-defect) may be due to:
(1) markedly reduced regional perfusion,
(2) impaired cellular membrane integrity, inadequate for the
active sequestration of the tracer into the cell,
(3) cell death (acute infarction), or
(4) scar tissue.
• Thus, fixed-defects on 3– 4 hr redistribution images may
represent only severely hypoperfused—and not necessarily
infarcted tissue
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
45. Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 16 page 291 -294
46. Late redistribution images
• Acquire a third set of images at 24-48 hours
• This would allow for redistribution of the tracer to very-
ischemic (yet viable) tissue
• It has been shown that 22% of fixed defects (at early
redistribution imaging) demonstrate normal Tl-201 uptake at
later redistribution.
• This may indicate a poorly perfused, yet viable region
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
47. • Late redistribution imaging, 24 to 48 hours after the initial
stress 201Tl injection, allows more time for redistribution to
occur and has good positive predictive value (PPV) for
improvement in function.
• Even with late redistribution imaging, the NPV is suboptimal,
because redistribution does not occur in some patients even
after a prolonged period, and in addition, image quality may
be poor.
• In such patients, 201Tl reinjection after late redistribution
imaging may provide further insight into defect reversibility
and thus viability.
48. 201Tl reinjection
• This may be necessary because redistribution depends on the
continued delivery of the tracer over the 3–4 hr period.
• If the blood concentration of Tl- 201 decreases a great deal,
there may be insufficient delivery of the tracer and the defect may
not fill-in during redistribution imaging
• The second injection of thallium with delayed imaging after
this repeat injection will give the myocytes with reduced
perfusion the greatest opportunity to sequester thallium
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
49. Rest-redistribution 201Tl imaging
• With this, images are obtained 15 to 20 minutes after tracer
injection at rest, reflecting regional blood flow at rest, and
images obtained 3 to 4 hours after redistribution reflect
myocyte viability.
• The finding of a reversible resting defect may identify areas of
myocardial hibernation .
• This finding appears to be an insensitive but specific sign of
potential improvement in regional function.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
50.
51. Rest-redistribution imaging protocol
• Rizzllo V. et al (2005) analysis of 22 studies (557 patients) using
Tl-201 rest-redistribution showed an average sensitivity and
specificity of 88% (range 44-100%) and 59% (range 22-92%)
respectively, and PPV 69% and NPV of 80%, for predicting
regional function recovery
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
52. Thallium-201re-injection protocol
• Re-injection protocol is an extra value on top of rest-
redistribution results. Rizzllo V. et al (2005) found lower
specificity of 50% having analysed 11 studies (301 patients)
and sensitivity of 86%, with low PPV of 57% and NPV of 83%
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
53. 99mTc Sestamibi and Tetrofosmin.
• The performance of the 99mTc agents in predicting improvement in
regional function after revascularization is similar to that of 201Tl.
• They do not share the redistribution properties of 201Tl
• The key finding to evaluate is the magnitude of tracer uptake in a
dysfunctional region.
• Normal uptake is consistent with preserved viability;
• only mild reduction in uptake is consistent with predominantly preserved
viability;
• moderate reduction in uptake is consistent with an admixture of viable and
infarcted tissue; and
• a severe defect is consistent with predominant infarct.
• Administration of nitrates to improve blood flow at rest before injection
of sestamibi appears to improve slightly the ability of these tracers to
detect myocardial viability
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
54. Technetium-99m sestamibi (MIBI)
• Rizzllo V. et al (2005) analysis of 20 studies (488 patients)
assessing Technetium-99m sestamibi studies, without the use
of nitrates concluded a lower sensitivity of 81%, but better
specificity of 66%, with PPV of 71% and NPV of 86%.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
55. Limitation and advantages
• The main limitations of SPECT include;
• higher cost compared to echocardiography,
• limited spatial resolution,
• potential difficulty in interpreting results in patients with
balanced myocardial ischemia (3-vessel disease) and the risk of
radiation.
• The main advantages include;
• extensive validation,
• increasing availability,
• good sensitivity and
• lower cost compared to PET.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
56. Prognostic value
• Cardiac SPECT viability study results can predict the recovery
of global LV function;
• 99mTc-sestamibi demonstrated a sensitivity of 81% and
specificity of 60%,
• thallium re-injection a sensitivity of 86% and specificity of 47%,
• thallium rest redistribution a sensitivity of 90% and specificity of
54%.
57. 3 PET
• MAGING OF GLUCOSE METABOLISM.
• Although fatty acids are the primary source of fuel in the fasting state,
• increased arterial glucose concentration in the fed state results in an increase in
insulin levels, stimulating glucose metabolism while inhibiting lipolysis.
• Fluorine-18 deoxyglucose (18-FDP), is the most validated radiotracer for cardiac
PET metabolism.
• The result is a switch in myocardial metabolism from predominant use of fatty
acids to glucose.
• The principle of using a metabolic tracer that tracks glycolysis is based on the
concept that glucose utilization may be preserved or increased relative to flow
in hypoperfused but viable (hibernating) myocardium, termed metabolism-
perfusion mismatch.
• Myocardial glucose use is absent in scarred or fibrotic tissue, represented by
metabolism-perfusion match.
58.
59. PET Blood Flow–Metabolism Mismatch.
• The extent of the PET mismatch pattern (enhanced FDG
uptake relative to blood flow) (PERFUSION-FDG MISMATCH)
• correlates with improvement in LV function after
revascularization as well as with the clinical course, magnitude of
improvement in HF symptoms, and survival after
revascularization.
• Patients with HF and an extensive PET match pattern
(PERFUSION-FDG MATCH) (diminished blood flow and severe
reduction in FDG uptake),
• representing predominant infarction, are unlikely to benefit
clinically from revascularization.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
60.
61. PATTERNS OF PERFUSION: 18F-FDG
IMAGES
• Normal perfusion and normal FDG or “normal match” of
healthy subjects or patients with low EF caused by nonischemic
cardiomyopathy (A)
• Abnormal perfusion and abnormal FDG or “abnormal match” of
myocardial scar (B)
• Abnormal perfusion and normal 18F-FDG or “abnormal mismatch”
of hibernating myocardium in the distal half of the LV (C)
• Normal perfusion and low FDG uptake or “reverse mismatch” of
adequately perfused myocardium metabolizing fatty acids rather
than glucose (D)
62.
63.
64. Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 16 page 291 -294
67. PET
• The recent analysis by Schinkel AF et al (2007) of 24 studies involving
756 patients noted weighted mean sensitivities and specificities of
92% and 63%, and positive and negative predictive values of 74%
and 87% respectively.
• Prognostic value
• A meta-analysis by Beanlands et al (1998) of 10 studies involving
1046 patients, found that,
• the mortality rate was higher in those who did not undergo
revascularization despite a PET scan confirming significant myocardial
viability.
• The annual death rate was 4% in those that had revascularization
versus 17% in those who did not undergo revascularization.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
68. Limitation and advantages
• The main limitations of PET include its
• high cost,
• limited availability, and
• the use of radio-active tracers.
• The main advantages include;
• established validity and
• excellent sensitivity.
• Compared with the SPECT, PET has better spatial and
temporal resolution, with better quality pictures and less
radiation.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
69. ACC/AHA/ASNC Guidelines for the Clinical Use of Cardiac Radionuclide Imaging—Executive Summary A Report
of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines
(ACC/AHA/ASNC Committee to Revise the 1995 Guidelines for the Clinical Use of Cardiac Radionuclide Imaging)
( Circulation. 2003;108:1404–1418.)
70. 4 Cardiovascular Magnetic
Resonance Imaging - CMR
• Three main techniques employed when using CMR in
assessing myocardial viability are;
• delayed enhancement (DE), known as late-gadolinium
enhancement (LGE),
• dobutamine stress (DS) and
• end-diastolic wall thickness (EDWT)
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
71. CardiovascularMagneticResonance
Imaging
• CMR imaging offers a multicomponent assessment of structure and
physiology to evaluate myocardial viability.
• From early cine CMR studies,
• end-diastolic wall thickness of 5.5 mm or more and
• dobutamine-induced systolic wall thickening of 2 mm or more
• have excellent sensitivity and specificity in the prediction of
segmental contractile recovery after revascularization.
• In addition, the transmural extent of myocardial scar detected by
LGE imaging accurately depicts a progressive stepwise decrease in
functional recovery despite successful coronary revascularization,
especially in myocardial regions of akinesia or dyskinesia.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
72. Cardiovascular Magnetic Resonance
Imaging {CMR}
• DE/LGE techniques demonstrate the status of myocardial perfusion
and tissue enhancement by i.v. administration of gadolinium-
chelated contrast.
• After 5min of contrast agent, T1-weighted images are acquired
which show regions of myocardial infarction exhibiting high signal
intensity i.e. high contrast enhancement.
• This hyperenhancment is related to the interstitial space between
collagen fibers, which is larger in scar tissue/non viable myocardium,
than in normal viable myocardium.
• This allows the determination of the extent of transmural disease,
which in turn correlates inversely with the likelihood of functional
recovery of the myocardium following revascularization.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
73. Extent transmurality of LGE is the gold
standard technique for viability
assessment by CMR.
LGE with a cutoff of less than 50%
transmurality of scar tissue had a high
sensitivity and a high negative predictive
value to predict functional recovery.
74.
75. AKINETIC SEGMENT
NO SCAR ON MRI
VIABLE
SEGMENT
BECAME FUNCTIONAL
POST
REVASCULARISATION
REVERSIBLE
DYSFUNCTION
76. AKINETIC SEGMENT
SCAR ON MRI
NON VIABLE
SCAR AND
AKINESIS WAS
PERSISTENT POST
REVASCULARISATION
IRREVERSIBLE
DYSFUNCTION
77. • A meta-analysis by Romero et al (2012), included 24
prospective trials in 698 patients; 11 studies assessing DE, 9
DS and 4 EDWT.
• DE demonstrated the highest sensitivity of 95% with
specificity of 51%, PPV of 69% and NPP of 90% in detecting
viable myocardium.
• The respective values for DS were 81%, 91%, 93% and 75%.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
78. Limitation and advantages
• The main limitations of CMR include;
• high cost,
• long study time,
• the requirement for breath-holding sequences and restrictions in patients
with implant devices and impaired renal function.
• However, advances in MRI technology are holding promises to reduce
imaging time, increase spatial resolution and adapt to scan implanted
devices.
• The main advantages of CMR include
• excellent anatomical details using steady state free precision (SSFP) cine
sequences in EDWT,
• good sensitivity/specificity with good interobserver/intraobserver agreement
in DE imaging, and
• excellent sensitivity offered with DS.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
79. Prognostic value
• Gerber et al (2012) included 144 patients with ischemic LV
dysfunction who had undergone DE imaging,
• then either received revascularization with PCI or CABG or
were managed conservatively
• demonstrated good prediction of survival, which was
significantly lower in patients who did not undergo
revascularization.
• Furthermore, it has been suggested that by combining CMR
with nuclear imaging additional benefits are obtained.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
80. Comparison of Imaging Techniques
for Viability Assessment.
• dobutamine echocardiography appears to be slightly more
specific, and
• PET techniques appear to have better accuracy.
• For patients with more severe LV dysfunction, in whom
thinner myocardial walls are often present, an advantage of
PET and CMR is their better spatial resolution for imaging
thinner objects.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
81. • On the other hand, low-dose dobutamine cine imaging
provides a highly specific physiologic assessment of the
• midmyocardial and subepicardial contractile reserve and early
after acute MI, when tissue edema is prominent.
• Contrast-enhanced CMR in combination with low-dose
dobutamine stimulation seems to be the most accurate
method, with a growing body of evidence to support it.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
83. Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
84.
85. Conclusion
• The recommended approach to assess myocardial viability begins
with either
• dobutamine echocardiogphy or
• radionuclide myocardial perfusion imaging,
• depending upon availability and local expertise.
• Despite cardiac magnetic resonance (CMR) and positron emission
tomography (PET) scanning have greater sensitivity they may be
more challenging to perform and not as widely available.
• Dobutamine stress echocardiography is the most widely used
method for assessing myocardial viability
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
86. • The best data on the clinical impact of myocardial viability assessment comes from a meta-
analysis and from two randomised trials;
• The Surgical Treatment for Ischemic Heart Failure (STICH) trial and The Canadian PPAR
study.
• The meta-analysis of 24 observational studies by Allman et al of 3088 patients,
demonstrated that revascularization compared to medical therapy,
• in patients with heart failure and myocardial viability have a significantly better survival
compared to patients with no viability who did poorly irrespective of therapy.
• However, perhaps contrary to expectation, both The STICH trial and The Canadian PPAR
study reported a lack of association between the presence or absence of residual
myocardial viability in patients mortality outcome when treatment was allocated
(revascularization vs medical therapy).
• Several limitations with potentially confounding effects may explain the seemingly opposing
results, and further trials are necessary to explore this outcome.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
87. • In a meta-analysis of outcome studies after viability imaging,
patients with evidence of preserved myocardial viability
• who underwent revascularization had a substantial reduction
in the risk of cardiac death during long-term follow-up
compared with those treated medically .
• current HF guidelines consider revascularization as a class IIa
indication (level of evidence B) to improve survival in patients
with mild to moderate LV systolic dysfunction and significant
multivessel CAD or proximal LAD stenosis when viable
myocardium is present.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014
88. Braunwald’s Heart Disease_ A Textbook of Cardiovascular Medicine (2018, Elsevier) 11th edition ch 16 page 291 -294
89. • Finally,
• it is important to note the European Society of Cardiology (ESC), the
European Association for Cardio- Thoracic Surgery (EACTS), and
American College of Cardiology/ American Heart Association
guidelines for
• revasculirazation of heart failure still recommend viability testing
as a part of diagnostic work up.
Assessment of Myocardial Viability: A Review of Current Non Invasive Imaging Techniques Ahmed talib et al march 2014