2nd degree, Mobitz I (Wenckebach Phenomenon) • LITFL

Definition of Mobitz I block (Wenckebach phenomenon)

Progressive prolongation of the PR interval culminating in a non-conducted P wave:

• PR interval is longest immediately before dropped beat
• PR interval is shortest immediately after dropped beat

AV block: 2nd degree, Mobitz type I

Other Features:

• The P-P interval remains relatively constant
• The greatest increase in PR interval duration is typically between the first and second beats of the cycle
• The RR interval progressively shortens with each beat of the cycle
• The Wenckebach pattern tends to repeat in P:QRS groups with ratios of 3:2, 4:3 or 5:4

Mechanism

• Mobitz I is usually due to reversible conduction block at the level of the AV node
• Malfunctioning AV nodal cells tend to progressively fatigue until they fail to conduct an impulse. This is different to cells of the His-Purkinje system which tend to fail suddenly and unexpectedly (i.e. producing a Mobitz II block)

Causes of Wenckebach Phenomenon

• Drugs: beta-blockers, calcium channel blockers, digoxin, amiodarone
• Increased vagal tone (e.g. athletes)
• Inferior MI
• Myocarditis
• Following cardiac surgery (mitral valve repair, Tetralogy of Fallot repair)

Clinical Significance

• Mobitz I is usually a benign rhythm, causing minimal haemodynamic disturbance and with low risk of progression to third degree heart block
• Asymptomatic patients do not require treatment
• Symptomatic patients usually respond to atropine
• Permanent pacing is rarely required

ECG Examples

Example 1

Mobitz I AV block

• Progressive prolongation of PR interval, with a subsequent non-conducted P wave
• Repeating 5:4 conduction ratio of P waves to QRS complexes
• Relatively constant P-P interval despite irregularity of QRS complexes

The first clue to the presence of Mobitz I AV block on this ECG is the way the QRS complexes cluster into groups, separated by short pauses. This phenomenon usually represents 2nd-degree AV block or non-conducted PACs; occasionally SA exit block.

Thanks to Dr Harry Patterson, FACEM, for providing this ECG. 

Example 2

Mobitz I AV block

• QRS complexes clustered in groups, separated by non-conducted P waves.
• The P:QRS conduction ratio varies from 5:4 to 6:5.
• Note the difference in PR interval between the first and last QRS complex of each group.

Example 3

Mobitz I AV block associated with inferior STEMI and RV infarction

• The majority of the rhythm strip shows 2:1 AV conduction, which makes discerning the type of block difficult (i.e. it could represent Mobitz I or Mobitz II)
• However, there is a single 3:2 Mobitz I cycle visible in the middle of the rhythm strip (QRS complexes 5 + 6). If you look hard, you can see a non-conducted P wave deforming the downslope of the T wave in complex 6
• Continuous rhythm strip recording revealed that this patient was indeed in Mobitz I AV block

AV block may occur in the context of an inferior STEMI due to ischaemia of the AV node, or due to increased vagal tone (Bezold-Jarisch reflex) 

An Interesting Case of Wenckebach

Mobitz I in a patient with atrial pacing following mitral valve surgery

• Small atrial pacing spikes precede the QRS complexes.
• The interval between the pacing spikes increases progressively until there is a non-conducted pacing spike.
• To find out the story behind this ECG, check out this chapter from the ECG Exigency series:”Post-op Pacing Puzzler“

Diagnosis Wenckebach?

This ECG rhythm strip was originally featured on this page as an example of Wenckebach AV block. Can you spot the “deliberate” mistake?

• Q1. What features of Wenckebach AV block are present on this ECG?
• Q2. What features of Wenckebach are notably ABSENT?
• Q3. What possible explanations could exist to explain this tracing?

Now read ECG exigency 18.2 for answers and explanations to these questions.

Related Topics

• AV block: 1st degree
• AV block: 2nd degree, Mobitz II
• AV block: 2nd degree, “fixed ratio blocks” (2:1, 3:1)
• AV block: 2nd degree, “high grade AV block”
• AV block: 3rd degree (complete heart block)

History

• Eponymythology History of Second-degree AV block. LITFL 2018
• Eponym Karel Frederik Wenckebach (1864 -1940). LITFL 2018
• Eponym. Woldemar Mobitz (1889 – 1951). LITFL 2018
• Eponym. John Hay (1873 – 1959). LITFL 2018

Advanced Reading

Online

• Wiesbauer F, Kühn P. ECG Mastery: Yellow Belt online course. Understand ECG basics. Medmastery
• Wiesbauer F, Kühn P. ECG Mastery: Blue Belt online course: Become an ECG expert. Medmastery
• Kühn P, Houghton A. ECG Mastery: Black Belt Workshop. Advanced ECG interpretation. Medmastery
• Rawshani A. Clinical ECG Interpretation ECG Waves
• Smith SW. Dr Smith’s ECG blog.

Textbooks

• Mattu A, Tabas JA, Brady WJ. Electrocardiography in Emergency, Acute, and Critical Care. 2e, 2019
• Brady WJ, Lipinski MJ et al. Electrocardiogram in Clinical Medicine. 1e, 2020
• Straus DG, Schocken DD. Marriott’s Practical Electrocardiography 13e, 2021
• Hampton J. The ECG Made Practical 7e, 2019
• Grauer K. ECG Pocket Brain (Expanded) 6e, 2014
• Brady WJ, Truwit JD. Critical Decisions in Emergency and Acute Care Electrocardiography 1e, 2009
• Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric 6e, 2008
• Mattu A, Brady W. ECG’s for the Emergency Physician Part I 1e, 2003 and Part II
• Chan TC. ECG in Emergency Medicine and Acute Care 1e, 2004
• Smith SW. The ECG in Acute MI. 2002 [PDF]

LITFL Further Reading

• ECG Library Basics – Waves, Intervals, Segments and Clinical Interpretation
• ECG A to Z by diagnosis – ECG interpretation in clinical context
• ECG Exigency and Cardiovascular Curveball – ECG Clinical Cases
• 100 ECG Quiz – Self-assessment tool for examination practice
• ECG Reference SITES and BOOKS – the best of the rest

Ed Burns

Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

Robert Buttner

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

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Not perpetual, but mobile – Nizhny Novgorod News

Many great minds fought over the invention of a perpetual motion machine, capable of generating an immense amount of energy at minimal cost and effort, but, as you know, all ideas about a perfect device were recognized as utopia. Olgerd Skripko from Nizhny Novgorod, who developed a new improved energy-efficient engine, partly managed to cope with a seemingly impossible task.

Practiced at the “bottling”

The first invention of Olgerd Yakovlevich, an artist by profession, was . .. a filling machine. After graduating from an art school, our hero managed to work at several machine-building plants, where he acquired good design and ergonomic skills. The acquired knowledge was most useful at a new place of work – a pharmaceutical company that produces liquid medicines. Medicines were poured here manually, and the productivity of the workflow left much to be desired (one employee managed to fill no more than three thousand bottles per hour, despite the fact that they had to work in two shifts).

Thanks to the filling machine designed by Skripko, the productive forces of the enterprise have increased no less than 13 times, and in just one hour the pourers began to produce 39 thousand ready-made bubbles!

However, the technique he designed did not cause much trepidation among the creator himself, because even at a young age our hero became seriously interested in aircraft modeling, or rather, rotary engines used both in aviation and in other industries. Over time, the innovator analyzed all the disadvantages of the device and decided to bring the design to perfection.

For fighters, it’s the most

– By the principle of operation, my device is similar to an internal combustion engine with the only difference being that in a conventional internal combustion engine there is a reciprocating motion, that is, the piston rises up and down and makes only one in four revolutions tact, – explains the designer. – In my engine, all processes occur simultaneously, in one direction, and if the pistons in the internal combustion engine have two dead points, then there is only one, and there is no reciprocating motion.

In simple terms, the motor avoids mechanical overload, it is more durable and energy efficient. The exhaust process here occurs continuously, while there is no combustion chamber, due to which the device is much smaller in size.

— Automotive industry, shipbuilding — for these industries, the compactness and durability of parts is of decisive importance, — continues the innovator. “My development is especially advantageous for aviation military equipment. Due to the small engine, a fighter-bomber, for example, holds more fuel, the freed space can be used to carry additional cargo.

An improved small-sized engine (by the way, at the patent competition, Olgerd Yakovlevich’s creation was awarded first place in the nomination “The Best Invention in the Nizhny Novgorod Region in the field of mechanical engineering and transport) has already become seriously interested abroad. In particular, Skripko received several offers from German manufacturers, but the innovator refused to implement his invention on the side. He is currently negotiating with one of the Nizhny Novgorod enterprises specializing in engine building.

Marina ANDRONOVA.

Reference “НН”

Perpetuum mobile (lat. Perpetuum Mobile) efficiency is greater than 100 percent). The first mention of a perpetual motion machine dates back to the 12th century, and Leonardo da Vinci and the famous Russian writer and literary critic Nikolai Chernyshevsky are among the innovators who tried to invent a perfect device.

Dmitry Yalov: “Our business turned out to be extremely mobile”

The economy of the Leningrad region, which was predicted to experience a significant decline due to the export orientation of key industries and the departure of large Western companies (such as IKEA, which had a factory in Tikhvin), showed unexpectedly positive results. Last year, the volume of industrial production in the region declined markedly. However, despite the tightening of sanctions, the industry quickly began to recover and already in April exceeded last year’s figures.

Dmitry Yalov, Deputy Chairman of the Government of the Leningrad Region, Chairman of the Committee for Economic Development and Investment Activity, spoke about the factors of growth, the current state of various industries, how the government helps businesses cope with problems, and the fate of investment projects in the region in an interview with RBC Petersburg. .

“What we did not expect”

― According to the latest data, the IPP of the Leningrad Region for January-April is 100. 4%, but the volume of shipment of manufacturing industries for the first quarter is 15.5% less than in Last year. What do these numbers say? Can we say that the decline in industrial production has been overcome? And the economy of the region as a whole – has it already overcome the crisis of 2022?

– The numbers we are seeing now are affected by two things. Firstly, at the beginning of 2022, the economy, in fact, was still working in conditions that were before the special military operation. In addition, in the first time after the start of the NWO, the pace of industrial production and shipments was largely anomalous, because everyone rushed to buy consumer goods – furniture, household appliances, etc.: they were afraid of a shortage or a strong rise in price. The real decline began later. Therefore, the current level of production is a fantastically good indicator; this is something that we did not expect and did not predict.

Secondly, shipment largely depends on the overstocking of warehouses, since products for various reasons, sometimes not related to the dynamics of production, first go to the warehouse and only then are shipped to customers.

– How would you characterize the current state of industry in the Leningrad Region?

– There are three industries that are currently experiencing some difficulties. The first, which, unfortunately, shows a decline of approximately 23% over the last 4 months, is the production of building materials. One of the reasons was the decrease in purchasing power and the cooling in the individual housing market after rapid growth during the pandemic.

The next area of ​​concern is the timber industry. It was largely focused on Europe. High-quality lumber, paper and pellets were exported there. This market is currently closed.

And the third industry is everything related to the production of automotive components. It is clear that the situation there is the most difficult, the most severe drawdown due to the withdrawal of foreign assembly plants. At the moment, there is virtually no one to produce auto components for anyone. Chinese automakers have not yet localized, while European, American, Korean and Japanese have already left.

All other sectors are doing well.

– What sectors can be called the most prosperous against the general background?

– Food production and mechanical engineering make the greatest positive contribution. Mechanical engineering grew by almost a third – in relation to the fall that was last year. The Tikhvin Freight Car Building Plant made a significant contribution to this growth. Due to problems with bearings, production there actually stopped in May last year, but by autumn it began to recover. Now, due to changes in logistics flows, there is a shortage of railcars on the Russian market, so their production is in full swing.

Also, more than 40% of growth was shown by the production of finished metal products. The production of beverages increased by 62% – this is import substitution in its purest form. The production of clothing increased 2.3 times, furniture – by 21%, medicines – by 18%, leather and leather products – 3 times.

“You can’t change one addiction for another”

― What is the fate of the most significant investment projects for the region, including those signed during SPIEF 2022 and at previous forums?

– Gas chemical projects are being successfully implemented. Among medium-sized projects, for example, the mass production of PVC sheets by the Karmatekh company has already begun. These sheets are used, for example, for printing signs, advertisements. The production is small, but very useful and important. Technopark “Marienburg” continues to develop production for the processing of polyolefins. Polyplast successfully implements its projects. In total, 16 projects are being implemented in the petrochemical industry. 9 projects – in mechanical engineering.

― To what extent does the process of import substitution compensate the region for the loss of Western suppliers?

– Import substitution projects are implemented in the region quite effectively. Let me give you one important example. In the spring of 2022, there was a problem with packaging, especially for food products. It was a critical risk, because selling milk, kefir, juices, etc. no one will be in glass bottles, as in Soviet times – this is inconvenient for both manufacturers and retail chains. And in terms of laminated cardboard, we depended on European suppliers. It wasn’t easy to readjust. At first, our manufacturers switched to Chinese laminated cardboard, and later the Elopak company located in the region was able to replace it. This example clearly demonstrates that it is impossible to change dependence on European suppliers for dependence on Chinese ones. There are industries, especially the food industry, where the concept of food safety is very important.

– Does the government help replace the loss of Western supplies?

– We work flexibly with the Ministry of Industry and Trade. Where domestic production has not yet been established, we ask that restrictive measures be lifted on foreign products, and in those areas that were urgently needed, duties were removed. And now, on the contrary, some duties have been returned – to protect the domestic market for those manufacturers who have managed to establish production.

Of course, we don’t have super-optimism. Unfortunately, some components, the same microchips, cannot yet be replaced, but in many areas, business is coping with import substitution. There were difficulties with chemical components for paper products, but they were solved. This helped to restore the work of Svetogorsk Pulp and Paper Mill, which lacked a significant number of components. It was possible to increase the production of components for the production of car tires at Ikon Tires (the successor to Nokian Tires, now owned by Tatneft). A real breakthrough has been achieved in many areas.

― Which of the business support measures developed by the Leningrad region government’s economic bloc turned out to be the most in demand?

– I have always advocated a fairly liberal approach to state intervention in the economy. Our task is not to interfere with business, but to help: somewhere to support financially, simplify regulatory procedures, create the necessary infrastructure, and advise. In the current situation, help is especially needed. Entrepreneurs use all possible support measures – both federal and regional.

I would like to point out some of the most popular support tools for small and medium-sized businesses. These are soft loans for working capital. In the portfolio of our Entrepreneurship Support Fund, they account for more than 90%.

It is worth noting the work of our development institutions – the Economic Development Agency of the Leningrad Region and the Center for Industry Support. These organizations systematically, and sometimes even manually, respond to business requests, help to find contacts with interested parties. The number of requests from investors is constantly growing. So, last year, 64 projects applied to AERLO for support, and for the first 4 months of 2023 – 85 projects.

– Is your Green Corridor system in demand among businesses?

– The numbers above are just talking about demand. Now the second stage of the Green Corridor system for the investor is being implemented. At the first stage, we fine-tuned the interaction of the project support system. Thanks to the operation of a single window, the response time for standard requests has been reduced from 30 to 7 days. Agreements have been concluded with resource-supplying organizations, and businesses can quickly receive an answer on the possibility of technical connection to electricity, water supply or gas.

At the second stage, we are working on upgrading the investor’s personal account. Now this is already a single digital window for communication between the investor and the project manager from the Agency, the investment commissioner from the municipal district.

The Green Corridor practice has been recognized by the Ministry of Economic Development of the Russian Federation as one of the best in Russia, and we are constantly approached from other regions with requests to share their experience.

The “Green Corridor” is especially useful for an average investor who, unlike a large one, does not have a large project team, no opportunity to hire consultants, no reliable connections in government offices, no team of lawyers who can deal with approvals. Such an investor cannot spend years on approvals, because in many cases during this time his project will lose its meaning. And he will either leave for another region, or he will buy or rent some ready-made areas. For such companies, fast, simple and free support is especially critical.

“It is too early to talk about stabilization”

– Is it possible to talk about the stabilization of the economy of the Leningrad Region after the sanctions strike in 2022? What are your forecasts for the situation in 2023?

– I think it’s premature to talk about stabilization. It is too early to say that we have already passed the bottom point and are on a sustainable growth trajectory. Although in the last quarter of last year and in the first quarter of this year, a slight increase in industrial production was recorded. In March of this year, compared to February, it even amounted to a significant 8.2%. But these are still very short intervals, they do not reflect the whole picture. I would like to say that this is a long-term trend, but as an economist I cannot. Only by autumn will it be possible to speak with confidence about what is happening.

Objectively, there are negative factors, for example, a reduction in consumer demand, because a 10% drop in consumption is a rather alarming factor that can drag the industry along with it. Much will depend on consumer sentiment, which is already associated with geopolitical factors, and not with economic ones.

Of the positive aspects, we are most pleased with the fact that the business turned out to be extremely mobile and efficient. This is the main point. At first there were panic moods, expectations that it would be like at 1990s. But both I and the experts were sure that this would not happen – and life confirmed the correctness of our words. In the nineties, there was a transition from an inefficient command and control economy to a market economy. And then there were simply no players who could quickly make decisions themselves.