1) Unipolar and bipolar pacing configurations determine the size of the electrical field for sensing and stimulation. Bipolar pacing has a smaller field to reduce muscle stimulation.
2) Pacemaker output is determined by pulse amplitude and width. Increasing either increases energy delivered. Strength-duration curves show relationships between pulse parameters and stimulation threshold.
3) Dual chamber pacing (DDD mode) provides atrioventricular synchrony for better cardiac output than single chamber pacing. It uses refractory periods and programmable delays to control ventricular pacing in response to atrial signals.
Speckle tracking echocardiography (STE) is an echocardiographic imaging technique that analyzes the motion of tissues in the heart by using the naturally occurring speckle pattern in the myocardium or blood when imaged by ultrasound.
Speckle tracking echocardiography (STE) is an echocardiographic imaging technique that analyzes the motion of tissues in the heart by using the naturally occurring speckle pattern in the myocardium or blood when imaged by ultrasound.
Aortic acceleration as a noninvasive index of left ventricular contractility ...Scintica Instrumentation
Key topics covered during this webinar include:
Evaluating cardiac contractility using mean or peak aortic acceleration
Investigating cardiac relaxation using mitral peak early velocity to peak atrial velocity ratio
Interpreting myocardial perfusion capacity through coronary flow reserve at baseline and with disease or other conditions
How Doppler Flow Velocity measurements can be used in translational research from mice to mammals
In a recent ground-breaking publication in Scientific Reports by Nature Research, Perez et al. highlight the use of noninvasive blood flow velocity measurements to quantify cardiac contractility as a surrogate to +dP/dt max. The article titled “Aortic acceleration as a noninvasive index of left ventricular contractility in the mouse” describes an alternate methodology to what is highly considered the gold standard for evaluating cardiac contractility and relaxation in preclinical research. The acute and terminal nature of acquiring +dP/dt using invasive blood pressure catheters is less than ideal, so finding a noninvasive surrogate is of great interest to the scientific research community.
Utilizing a Doppler Flow Velocity System (DFVS) from Indus Instruments, Dr. Reddy and his group show that peak acceleration in the ascending aorta can be used in place of invasive LVP catheters. This novel technique enables serial measurements in the same animal, which reduces animal-to-animal variability, allows for the use of fewer subjects, and decreases data collection time.
Please join us during our upcoming webinar on March 4th, 2021 at 11am EST to hear Dr. Reddy present his findings with a LIVE Q&A session at the end.
References:
Perez, J.E.T., Ortiz-Urbina, J., Heredia, C.P. et al. Aortic acceleration as a noninvasive index of left ventricular contractility in the mouse. Sci Rep 11, 536 (2021)
Also known as an electrocardiogram or an EKG, an ECG is a test that detects and records the strength and timing of the electrical activity in your heart. This information is recorded on a graph that shows each phase of the electrical signal as it travels through your heart.
Information and Knowledge for medical professionals about electrocardiography including rationale, standardization, and interpretation. This is part one of
All the major religions and belief systems in the UK support the principles of organ donation and transplantation and accept that organ donation is an individual choice.
We understand that you may have questions about whether your faith or beliefs affect your ability to become an organ donor. We're here to help support your decision, and have provided a selection of resources to help make sure you get the information you need.
Find out more about different attitudes to organ donation by selecting a faith or belief system below, or alternatively please consult the adviser from your religion or belief group.
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CRISPR-Cas9, a revolutionary gene-editing tool, holds immense potential to reshape medicine, agriculture, and our understanding of life. But like any powerful tool, it comes with ethical considerations.
Unveiling CRISPR: This naturally occurring bacterial defense system (crRNA & Cas9 protein) fights viruses. Scientists repurposed it for precise gene editing (correction, deletion, insertion) by targeting specific DNA sequences.
The Promise: CRISPR offers exciting possibilities:
Gene Therapy: Correcting genetic diseases like cystic fibrosis.
Agriculture: Engineering crops resistant to pests and harsh environments.
Research: Studying gene function to unlock new knowledge.
The Peril: Ethical concerns demand attention:
Off-target Effects: Unintended DNA edits can have unforeseen consequences.
Eugenics: Misusing CRISPR for designer babies raises social and ethical questions.
Equity: High costs could limit access to this potentially life-saving technology.
The Path Forward: Responsible development is crucial:
International Collaboration: Clear guidelines are needed for research and human trials.
Public Education: Open discussions ensure informed decisions about CRISPR.
Prioritize Safety and Ethics: Safety and ethical principles must be paramount.
CRISPR offers a powerful tool for a better future, but responsible development and addressing ethical concerns are essential. By prioritizing safety, fostering open dialogue, and ensuring equitable access, we can harness CRISPR's power for the benefit of all. (2998 characters)
Leading the Way in Nephrology: Dr. David Greene's Work with Stem Cells for Ki...Dr. David Greene Arizona
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Navigating the Health Insurance Market_ Understanding Trends and Options.pdfEnterprise Wired
From navigating policy options to staying informed about industry trends, this comprehensive guide explores everything you need to know about the health insurance market.
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CHAPTER 1 SEMESTER V PREVENTIVE-PEDIATRICS.pdfSachin Sharma
This content provides an overview of preventive pediatrics. It defines preventive pediatrics as preventing disease and promoting children's physical, mental, and social well-being to achieve positive health. It discusses antenatal, postnatal, and social preventive pediatrics. It also covers various child health programs like immunization, breastfeeding, ICDS, and the roles of organizations like WHO, UNICEF, and nurses in preventive pediatrics.
Medical Technology Tackles New Health Care Demand - Research Report - March 2...pchutichetpong
M Capital Group (“MCG”) predicts that with, against, despite, and even without the global pandemic, the medical technology (MedTech) industry shows signs of continuous healthy growth, driven by smaller, faster, and cheaper devices, growing demand for home-based applications, technological innovation, strategic acquisitions, investments, and SPAC listings. MCG predicts that this should reflects itself in annual growth of over 6%, well beyond 2028.
According to Chris Mouchabhani, Managing Partner at M Capital Group, “Despite all economic scenarios that one may consider, beyond overall economic shocks, medical technology should remain one of the most promising and robust sectors over the short to medium term and well beyond 2028.”
There is a movement towards home-based care for the elderly, next generation scanning and MRI devices, wearable technology, artificial intelligence incorporation, and online connectivity. Experts also see a focus on predictive, preventive, personalized, participatory, and precision medicine, with rising levels of integration of home care and technological innovation.
The average cost of treatment has been rising across the board, creating additional financial burdens to governments, healthcare providers and insurance companies. According to MCG, cost-per-inpatient-stay in the United States alone rose on average annually by over 13% between 2014 to 2021, leading MedTech to focus research efforts on optimized medical equipment at lower price points, whilst emphasizing portability and ease of use. Namely, 46% of the 1,008 medical technology companies in the 2021 MedTech Innovator (“MTI”) database are focusing on prevention, wellness, detection, or diagnosis, signaling a clear push for preventive care to also tackle costs.
In addition, there has also been a lasting impact on consumer and medical demand for home care, supported by the pandemic. Lockdowns, closure of care facilities, and healthcare systems subjected to capacity pressure, accelerated demand away from traditional inpatient care. Now, outpatient care solutions are driving industry production, with nearly 70% of recent diagnostics start-up companies producing products in areas such as ambulatory clinics, at-home care, and self-administered diagnostics.
3. SM
-
Unipolar
Stimulation
& Sensing
Polarity of the Pacemaker System
• Larger “antenna” for sensing
√ bigger signals
√ more interference (myopotentials !)
• Big spike on ECG
• Pectoral (pocket) stimulation possible
+
+
4. SM
CONFIGURATION
UNIPOLAIRE
-
Polarity of the Pacemaker System
Bipolar
Stimulation
& Sensing
+
• Smaller “antenna” for sensing
√ smaller, more specific signals
√ less interference
• Spike difficult to see on ECG
• No pectoral (pocket) stimulation
5. SM
Fixation mechanisms of the Electrode
Passive fixation
Wingtips
Active fixation
Screw
Active fixation
Tines
7. SM
• Inversely proportional to current density
(amount of current per mm²)
• Electrode surface as small as possible
• Compromise with the sensing of intracardiac
signals, for which a larger surface is required
• Surface of the electrode: around 6 to 8 mm²
Stimulation Threshold
17. SM
Energy and Longevity
E = x PW
V
R
²
Example : 5 V, 500 Ω , 0.5 ms
2.5 V, 500 Ω , 0.5 ms
E = x 0.5 = 25 µJ
5 ²
500
18. SM
Energy and Longevity
E = x PW
V
R
²
Example : 5 V, 500 Ω , 0.5 ms
2.5 V, 500 Ω , 0.5 ms
E = x 0.5 = 25 µJ
5 ²
500
E = x 0.5 = 6.25 µJ
2.5
500
²
( Increased longevity! )
25. SM
Single Chamber Pacemaker (VVI)
Easy to implant a ventricular lead
Easy to program the pacemaker
Easy follow-up
Longevity of > 6 years
Only one pacing rate (except rate responsive
pacemakers)
26. SM
NASPE/ BPEG Generic (NBG) Pacemaker Code
I. Chamber II. Chamber III. Response to IV. Programmability V. Antitachy
Paced Sensed Sensing Rate Modulation arrhythmia
funct.
O= none O= none O= none O= none O= none
A=atrium A= atrium T= triggered P= simple P= pacing
V= ventricle V= ventricle I= inhibited M= multi S= shock
D= dual D= dual D= dual C= communication D= dual
(A+V) (A+V) (T+I) R= Rate Modulation
Manufacturers’ Designation only:
S= single S= single
(A or V) (A or V)
29. SM
VVI MODE
Automatic
Interval
• Automatic interval starts
from a paced complex (to
the next paced complex)
• Escape interval starts from
a sensed complex (to the
next paced complex)
Escape Interval
If the intervals are equal:
•No hysteresis
If the escape interval > automatic interval:
•Hysteresis
37. SM
DDD Pacemaker
A DDD pacemaker puts in the
beat that’s missing in order to
maintain AV synchrony
38. SM
DDD timing
Ap Vp Ap VpAsVs As Vs PVC
AA interval
AV-D
NPAVD
VB
CSW
PVARP ARE
VRP
VTL
VA int.
TARP
39. SM
DDD Pacing
• Indications:
– Sick Sinus Syndrome
– AV block
– Chronic Sinus Bradycardia with AV conduction
problems
– Pacemaker Syndrome (instead of VVI)
– AV synchrony needed (instead of VVI)
• Contraindication:
– Atrial tachyarrhythmias
40. SM
DUAL CHAMBER STIMULATION
Advantages AV Synchrony
Variability of the pacing rate
Results Increase of the cardiac output
Improved quality of life
No Pacemaker Syndrome
41. SM
AV Synchrony
• Cardiac Output = Heart Rate X Stroke Volume
= amount of blood expelled from the heart per
minute
• Ventricles contribute 70 % to the C.O.
• Atria contribute 30 % to the C.O.
If there is AV synchrony: C.O. = 100 %
+ appropriate opening and closing of AV valves!
42. SM
Pacemaker Syndrome
• = the result of a loss of AV synchrony
atria contract against closed valves
• Symptoms: Cannon A waves
Pulsations in the neck
Fatigue
Diziness
Syncope
43. SM
NASPE/ BPEG Generic (NBG) Pacemaker Code
I. Chamber II. Chamber III. Response to IV. Programmability V. Antitachy
Paced Sensed Sensing Rate Modulation arrhythmia
funct.
O= none O= none O= none O= none O= none
A=atrium A= atrium T= triggered P= simple P= pacing
V= ventricle V= ventricle I= inhibited M= multi S= shock
D= dual D= dual D= dual C= communication D= dual
(A+V) (A+V) (T+I) R= Rate Modulation
Manufacturers’ Designation only:
S= single S= single
(A or V) (A or V)
46. SM
Differential AV delay
• AV s < AV p
• Provides shorter AV delay following sensed atrial
events than following paced atrial events
• atrial sensing and pacing for optimal ventricular filling
• Equalizes true PR interval after
47. SM
Adaptive AV delay
• Adapts AV delay after atrial events to changes in atrial
interval:
if atrial interval shortens AV delay shortens
• Maintains relatively constant relationship between AV
delay and total cardiac cycle for optimal hemodynamics
(AV delay = 15-20 % of total cardiac cycle)
• Improves upper rate characteristics
48. SM
Adaptive AV delay
• AV delay adapts in an 8:1 ratio
• For every shortening of the AA interval of 8 ms,
the AV delay shortens by 1 ms (but never < 75
ms)
• Enhances ventricular filling and increases cardiac
output
• Improves upper rate behaviour characteristics
49. SM
NASPE/ BPEG Generic (NBG) Pacemaker Code
I. Chamber II. Chamber III. Response to IV. Programmability V. Antitachy
Paced Sensed Sensing Rate Modulation arrhythmia
funct.
O= none O= none O= none O= none O= none
A=atrium A= atrium T= triggered P= simple P= pacing
V= ventricle V= ventricle I= inhibited M= multi S= shock
D= dual D= dual D= dual C= communication D= dual
(A+V) (A+V) (T+I) R= Rate Modulation
Manufacturers’ Designation only:
S= single S= single
(A or V) (A or V)
50. SM
DDI Pacing
• DDI= DVI + Atrial sensing / inhibition
• DDI is NOT a pacemaker type but a MODE
• DDD pacemaker: mode switch to DDI
Paroxysmal atrial tachycardia’s: no tracking
allowed!
Switch from DDD to DDI
51. SM
Refractory Periods
• Refractory period =
a programmable interval occurring after the
delivery of a pacing impulse or after a sensed
intrinsic complex, during which the pacemaker
can sense signals but chooses to ignore them
52. SM
Atrial Refractory Period
• AV delay
• PVARP= Post Ventricular Atrial Refractory Period
TARP = Total Atrial Refractory Period
= AV delay + PVARP
55. SM
Clinical Considerations in DDD pacing
• Upper Rate Behaviour
• Control of Pacemaker Mediated Tachycardia
• Crosstalk Inhibition Protection
56. SM
Upper Rate Behaviour
• The pacemaker’s response to sensed rapid atrial
rates.
• A rapid atrial rate is a rate > Upper Rate Limit (URL) or
Ventricular Tracking Limit (VTL)
• VTL= a rate beyond which 1:1 tracking will NOT occur
= “the absolute speed limit in the ventricle”
(max. 180 bpm)
58. SM
Wenckebach Response
• Progressive prolongation of the AV delay until a
ventricular output pulse is missed in response
to atrial activity exceeding the ventricular
tracking limit
62. SM
How to recognize Wenckebach?
• Grouped beating
• Progressive prolongation of the AV delay until
the ventricular output is missed
• Ventricular pacing at the VTL
63. SM
Pacemaker Mediated Tachycardia (PMT)
Rapid ventricular pacing due to RETROGRADE
CONDUCTION, most commonly at exactly the
upper rate limit.
64. SM
Retrograde Conduction
• Propagation of an impulse from the ventricle
back to the atrium.
• Also known as VA conduction
• 60 % of the population have the ability to conduct
retrogradely
• 33 % of patients with complete heart block have the
ability to conduct retrogradely
• Average retrograde conduction time= 235ms ± 55 ms
68. SM
PMT Prevention
• Program PVARP longer than VA
conduction time
• PVARP + AV delay = TARP determines 2:1 block
250 ms + 150 ms = 400 ms 2:1 block at 150 bpm
350 ms + 150 ms = 500 ms 2:1 block at 120 bpm
70. SM
Tachycardia Termination Algorithm (TTA)
• After 15 consecutive paced ventricular events
at EXACTLY the upper rate limit, the 16 th
ventricular output pulse is dropped.
• TTA breaks PMT, but does not prevent it.
• TTA breaks PMT only at the upper rate limit.
71. SM
Retrograde P wavesPVC
1 2 14 15 Inhibition of the 16 th
ventricular output
pulse
Tachycardia Termination Algorithm
74. SM
Factors Affecting Crosstalk
• Atrial pulse amplitude and pulse width
• Ventricular sensitivity
• Anatomical location of atrial and ventricular
electrodes
75. SM
Managing Crosstalk
• Atrial Pulse Energy
• Ventricular Sensitivity
• Ventricular Blanking Period
• Crosstalk Sensing Window
• Safety Pacing (Non Physiologic AV delay)
76. SM
Ventricular Blanking Period (VB)
• A short (21-75 ms) period that begins
simultaneously with an atrial output pulse and
during which the ventricular sense amplifier is
totally blind to incoming signals.
AV delay
VB
78. SM
Crosstalk Sensing Window
• A short (25-40ms) period of time that starts at
the end of the ventricular blanking period
• If during this time interval the ventricular lead
senses an event (may be crosstalk, may also
be a PVC), a ventricular output pulse is
delivered after 100 ms = SAFETY PACING
• This 100 ms time period = Non Physiologic AV
delay
79. SM
Safety Pacing
Non Physiologic AV delay (100 ms)
Ventricular Blanking
Period
Crosstalk Sensing Window
Atrial Output
Ventricular Output
Ventricular Sense
