Name: measuring pressure volume loops in the mouse
Uploaded: 2016-05-02T15:00:00.000+00:00
Duration: 9 min 15 s
Description: Watch this Scientific Journal Video about Measuring Pressure Volume Loops in the Mouse at JoVE.com

O autor gostaria de reconhecer financiamento do NHLBI (K08 HL102066 e R01 HL114832).

<ol>
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The author has nothing to disclose.

Existem três passos críticos neste processo: 1) a colocação do tubo endotraqueal e ventilação adequado, 2) a colocação do cateter IV jugular, e 3) a colocação correcta do cateter PV no ventrículo esquerdo. Determinação da taxa respiratória apropriada é uma parte importante do fornecimento de suporte ventilatório. ratinhos conscientes geralmente manter a ventilação alveolar com respirações superficiais rápidas. Em geral, os ratinhos ventilados terá volumes correntes muito maiores. Assim, é necessá...

A doença cardiovascular continua a ser uma causa significativa de morbilidade e mortalidade em todo o mundo 1. Doenças do coração apresentar desafios particularmente difíceis no desenvolvimento de novas terapias. Os avanços no campo da genética para proporcionar a possibilidade de identificar uma grande variedade de potenciais contribuintes genética para o desenvolvimento de doença cardíaca. A natureza integradora do sistema cardiovascular exige que esses alvos genéticos ser validados em modelos animais intactos. Os custos de flexibilidade e baixa habitação genéticas do rato tê-lo trazido para o primeiro plano para a avaliação do papel fisiológico de um determinado gene. O pequeno tamanho do mouse apresenta alguns desafios únicos para a avaliação da função cardíaca. Existem várias modalidades que podem fornecer informações sobre a função cardíaca, mas apenas a medição simultânea da pressão ventricular e o volume permite pressão-volume (PV) análise do lacete da função ventricular. PV laços tudoOW função cardíaca a ser analisada independente da sua conexão com a vasculatura; um factor importante na determinação do papel funcional de um elemento genético particular. A avaliação de loops de pressão-volume tem sido utilizada tanto experimentalmente e clinicamente por muitos anos e extensa literatura existe sobre a análise desses conjuntos de dados 2,3. A adaptação da tecnologia de ciclo PV para o rato tem sido um importante avanço para a compreensão da fisiologia cardíaca murino 4-6. Cateter de tecnologias baseadas na ansa PV acoplar um transdutor de pressão e a utilização de condutância para estimar o volume do ventrículo. O volume ventricular é determinado por análise de alterações em um campo eléctrico gerado pelo cateter. Este método modelos do ventrículo como um cilindro, cuja altura é definida pela distância entre os eléctrodos no cateter e o raio é calculado a partir da condução de um campo eléctrico através do sangue emventrículo 7-9. O sinal de condutância medida pelo cateter tem duas componentes. A primeira é a condução através do sangue; esta varia com o volume do ventrículo e constitui o sinal primário usado para determinar o volume do ventrículo. O segundo componente resultante da condução através e ao longo da parede do ventrículo. Isto é chamado de condutância paralela e deve ser removido, a fim de determinar o volume do ventrículo absoluto. Há dois sistemas disponíveis comercialmente para a recolha de dados de pressão-volume no laboratório de pesquisa e o método utilizado para calcular e remover a condutância paralela é a principal diferença entre eles 6,10,11. cateteres condutância exigem a injecção de uma solução salina hipertónica para o cálculo da condutância paralelo. Esta injecção transitoriamente muda a condutividade do sangue no ventrículo, enquanto que a condutividade da parede mantém-se constante. A partir destes dados, é possível determinar acomponente do sinal de condutância que se origina a partir do sangue e o que vem a partir da parede do ventrículo. Esta abordagem assume que a condutância paralelo não varia durante o ciclo cardíaco. O método baseia-se na admissão mudanças de fase no campo eléctrico para avaliar a contribuição da parede ventricular para o sinal total de volume. Este método baseia-se uma variedade de constantes predeterminadas para a condutividade do sangue e do miocárdio para determinar o volume final, mas torna medidas contínuas de condutância paralela durante o ciclo cardíaco. Ambos estes sistemas fornecem boas estimativas do volume ventricular esquerdo e as diferenças entre eles não são susceptíveis de ser f isiologicamente significativa. O modelo cilíndrico do ventrículo e outras premissas tornar estas abordagens baseadas em cateter não tão precisos quanto outras modalidades, mas esses dados são fornecidos numa base de batimento a batimento que é essencial para a avaliação das medidas independentes de carga da função cardíaca. O procedimento aqui descrito é utilizado no meu laboratório e apresentou dados de um grande número de estudos que examinam os mecanismos patofisiológicos básicos de distrófica cardiomiopatia 12-18. O procedimento descrito abaixo é um dos dois que pode ser usado para obter dados de espira PV. Embora muitos dos princípios são aplicáveis ​​para qualquer abordagem, este protocolo vai se concentrar em uma abordagem apical de tórax aberto; um protocolo de tórax fechado foi detalhado em outros lugares 19,20. Enquanto o processo será descrito em pormenor, os princípios gerais são importantes para expor o coração com danos mínimos para quer o coração ou os pulmões. Durante todo o protocolo é importante lembrar que este é um procedimento não-sobrevivência e que tendo uma boa exposição do coração é criticamente importante para a colocação correcta do cateter.

<table><tbody><tr><td>Dumont 5/45 (2)</td><td>Fine Science Tools</td><td>11251-33</td><td></td></tr><tr><td>Vessel Dilating Forceps</td><td>Fine Science Tools</td><td>18153-11</td><td></td></tr><tr><td>Castroviejo Micro Dissecting Spring Scissor</td><td>Roboz Instruments</td><td>RS-5668</td><td></td></tr><tr><td>Octogon Forceps - Serrated/Curved</td><td>Fine Science Tools</td><td>11041-08</td><td></td></tr><tr><td>Octogon Forceps - Serrated/Straight</td><td>Fine Science Tools</td><td>11040-08</td><td></td></tr><tr><td>Dissector Scissors- Heavy Blade</td><td>Fine Science Tools</td><td>14082-09</td><td></td></tr><tr><td>Transpore Surgical Tape</td><td>3M</td><td>1527-1</td><td></td></tr><tr><td>3-0 Silk Suture</td><td>Fine Science Tools</td><td>18020-30</td><td></td></tr><tr><td>TOPO Ventilator</td><td>Kent Scientific</td><td>TOPO</td><td></td></tr><tr><td>Martin ME 102 Electrosurgical Unit</td><td>Harvard Apparatus</td><td>PY2 72-2484</td><td></td></tr><tr><td>Syringe Pump</td><td>Lucca Technologies</td><td>GenieTouch</td><td></td></tr><tr><td>Stereomicroscope with boom stand</td><td>Nikon</td><td>SMZ-800N</td><td></td></tr><tr><td>Thermocouple Thermometer</td><td>Cole Parmer</td><td>EW-91100-40</td><td></td></tr><tr><td>T/Pump Warm Water Recirculator</td><td>Kent Scientific</td><td>TP-700</td><td></td></tr><tr><td>ADVantage Pressure-Volume System</td><td>Transonic</td><td>ADV500</td><td></td></tr><tr><td>Data Acquision and Analysis</td><td>DSI</td><td>Ponemah ACQ-16</td><td></td></tr></tbody></table>

measuring pressure volume loops in the mouse

Compreender as causas e progressão da doença cardíaca apresenta um desafio significativo para a comunidade biomédica. A flexibilidade genética do mouse oferece um grande potencial para explorar a função cardíaca no nível molecular. O tamanho reduzido do rato apresenta alguns desafios no que diz respeito à realização de fenotipagem cardíaco detalhado. Miniaturização e outros avanços na tecnologia fizeram muitos métodos de avaliação cardíaca possível no mouse. Destes, a coleta simultânea de dados de pressão e volume fornece uma imagem detalhada da função cardíaca que não está disponível através de qualquer outra modalidade. Aqui, um procedimento detalhado para a recolha de dados de loop pressão-volume é descrito. Incluído é uma discussão sobre os princípios subjacentes às medições e as potenciais fontes de erro. manejo anestésico e abordagens cirúrgicas são discutidos em grande detalhe como ambos são cruciais para a obtenção de medida hemodinâmica de alta qualidades. Os princípios do desenvolvimento protocolo de hemodinâmica e aspectos relevantes da análise dos dados também são abordados.

Por convenção, o volume é representada graficamente no eixo X e a pressão sobre o eixo dos Y como na Figura 1. As malhas de pressão-volume decorrentes traçando pressão contra o volume deve assemelhar a um rectângulo, os bordos verticais que representam as alterações isovolumétrica de pressão (isto é, quando ambos valvas mitral e aórtica estão fechados). A horizontal inferior representa enchimento ventricular através da válvula mitral e a parte h...

Watch this Scientific Journal Video about Measuring Pressure Volume Loops in the Mouse at JoVE.com

Measuring Pressure Volume Loops in the Mouse

Este manuscrito descreve um protocolo detalhado para a recolha de dados de pressão-volume do mouse.

Medição do volume Pressão Loops no mouse

Understanding the causes and progression of heart disease presents a significant challenge to the biomedical community. The genetic flexibility of the ...

measuring-pressure-volume-loops-in-the-mouse

Research

JoVE Journal

Biology

16.3K visualizações.  University of Minnesota.  Este manuscrito descreve um protocolo detalhado para a recolha de dados de pressão-volume do mouse. 

Vídeo: Measuring Pressure Volume Loops in the Mouse

Measuring Left Ventricular Pressure in Late Embryonic and Neonatal Mice

Blood pressure increases significantly during embryonic and postnatal development in vertebrate animals. In the mouse, blood flow is first detectable around embryonic day (E) 8.51. Systolic left ventricular (LV) pressure is 2 mmHg at E9.5 and 11 mmHg at E14.52. At these mid-embryonic stages, the LV is clearly visible through the chest wall for invasive pressure measurements because the ribs and skin are not fully developed. Between E14.5 and birth (approximately E21) imaging methods must be used to view the LV. After birth, mean arterial pressure increases from 30 - 70 mmHg from postnatal day (P) 2 - 353. Beyond P20, arterial pressure can be measured with solid-state catheters (i.e. Millar or Scisense). Before P20, these catheters are too big for developing mouse arteries and arterial pressure must be measured with custom pulled plastic catheters attached to fluid-filled pressure transducers3 or glass micropipettes attached to servo null pressure transducers4.
Our recent work has shown that the greatest increase in blood pressure occurs during the late embryonic to early postnatal period in mice5-7. This large increase in blood pressure may influence smooth muscle cell (SMC) phenotype in developing arteries and trigger important mechanotransduction events. In human disease, where the mechanical properties of developing arteries are compromised by defects in extracellular matrix proteins (i.e. Marfan's Syndrome8 and Supravalvular Aortic Stenosis9) the rapid changes in blood pressure during this period may contribute to disease phenotype and severity through alterations in mechanotransduction signals. Therefore, it is important to be able to measure blood pressure changes during late embryonic and neonatal periods in mouse models of human disease.
We describe a method for measuring LV pressure in late embryonic (E18) and early postnatal (P1 - 20) mice. A needle attached to a fluid-filled pressure transducer is inserted into the LV under ultrasound guidance. Care is taken to maintain normal cardiac function during the experimental protocol, especially for the embryonic mice. Representative data are presented and limitations of the protocol are discussed.

Measuring left ventricular pressure (LV) in embryonic and neonatal mice is described. Pressure is measured by inserting a needle connected to a fluid-filled transducer into the LV under ultrasound guidance. Care must be taken to maintain normal cardiac function during the experimental protocol.

Pressão Ventricular Esquerda de medição no final de Ratos embrionárias e Neonatal

Blood pressure increases significantly during embryonic and postnatal development in vertebrate animals. In the mouse, blood flow is first detectable ...

Bioengenharia

Right Ventricular Systolic Pressure Measurements in Combination with Harvest of Lung and Immune Tissue Samples in Mice

The function of the right heart is to pump blood through the lungs, thus linking right heart physiology and pulmonary vascular physiology. Inflammation is a common modifier of heart and lung function, by elaborating cellular infiltration, production of cytokines and growth factors, and by initiating remodeling processes 1.
Compared to the left ventricle, the right ventricle is a low-pressure pump that operates in a relatively narrow zone of pressure changes. Increased pulmonary artery pressures are associated with increased pressure in the lung vascular bed and pulmonary hypertension 2. Pulmonary hypertension is often associated with inflammatory lung diseases, for example chronic obstructive pulmonary disease, or autoimmune diseases 3. Because pulmonary hypertension confers a bad prognosis for quality of life and life expectancy, much research is directed towards understanding the mechanisms that might be targets for pharmaceutical intervention 4. The main challenge for the development of effective management tools for pulmonary hypertension remains the complexity of the simultaneous understanding of molecular and cellular changes in the right heart, the lungs and the immune system.
Here, we present a procedural workflow for the rapid and precise measurement of pressure changes in the right heart of mice and the simultaneous harvest of samples from heart, lungs and immune tissues. The method is based on the direct catheterization of the right ventricle via the jugular vein in close-chested mice, first developed in the late 1990s as surrogate measure of pressures in the pulmonary artery5-13. The organized team-approach facilitates a very rapid right heart catheterization technique. This makes it possible to perform the measurements in mice that spontaneously breathe room air. The organization of the work-flow in distinct work-areas reduces time delay and opens the possibility to simultaneously perform physiology experiments and harvest immune, heart and lung tissues.
The procedural workflow outlined here can be adapted for a wide variety of laboratory settings and study designs, from small, targeted experiments, to large drug screening assays. The simultaneous acquisition of cardiac physiology data that can be expanded to include echocardiography5,14-17 and harvest of heart, lung and immune tissues reduces the number of animals needed to obtain data that move the scientific knowledge basis forward. The procedural workflow presented here also provides an ideal basis for gaining knowledge of the networks that link immune, lung and heart function. The same principles outlined here can be adapted to study other or additional organs as needed.

A specific and rapid protocol to simultaneously investigate right heart function, lung inflammation, and the immune response is described as a learning tool. Video and figures describe physiology and microdissection techniques in an organized team-approach that is adaptable to be used for small to large sized studies.

Sistólica do ventrículo direito Medição de Pressão em combinação com colheita de amostras de tecido pulmonar e imunológica em ratos

The function of the right heart is to pump blood through the lungs, thus linking right heart physiology and pulmonary vascular physiology. Inflammation is ...

Imunologia e Infecção

Measuring Blood Pressure in Mice using Volume Pressure Recording, a Tail-cuff Method

The CODA 8-Channel High Throughput Non-Invasive Blood Pressure system measures the blood pressure in up to 8 mice or rats simultaneously. The CODA tail-cuff system uses Volume Pressure Recording (VPR) to measure the blood pressure by determining the tail blood volume. A specially designed differential pressure transducer and an occlusion tail-cuff measure the total blood volume in the tail without the need to obtain the individual pulse signal. Special attention is afforded to the length of the occlusion cuff in order to derive the most accurate blood pressure readings. VPR can easily obtain readings on dark-skinned rodents, such as C57BL6 mice and is MRI compatible. The CODA system provides you with measurements of six (6) different blood pressure parameters; systolic and diastolic blood pressure, heart rate, mean blood pressure, tail blood flow, and tail blood volume. Measurements can be made on either awake or anesthetized mice or rats. The CODA system includes a controller, laptop computer, software, cuffs, animal holders, infrared warming pads, and an infrared thermometer. There are seven different holder sizes for mice as small as 8 grams to rats as large as 900 grams.

The CODA 8-Channel High Throughput Non-Invasive Blood Pressure system measures the blood pressure in up to 8 mice or rats simultaneously. This tail-cuff system uses Volume Pressure Recording (VPR) to measure the blood pressure by determining the tail blood volume.

Medição da pressão arterial em ratos usando Recording Volume de pressão, um método de cauda-manguito

The CODA 8-Channel High Throughput Non-Invasive Blood Pressure system measures the blood pressure in up to 8 mice or rats simultaneously. The CODA ...

Biologia

Catheterization of Intestinal Loops in Ruminants

The intestine is a complex structure that is involved not only in absorption of nutrients, but also acts as a barrier between the individual and the outside world. As such, the intestine plays a pivotal role in immunosurveillance and protection from enteric pathogens. Investigating intestinal physiology and immunology commonly employs 'intestinal loops' as an experimental model. The majority of these loop models are non-recovery surgical procedures that study short-term (&lt;24 hr) changes in the intestine (1-3). We previously created a recovery intestinal loop model to specifically measure long-term (&lt;6 mo) immunological changes in the intestine of sheep following exposure to vaccines, adjuvants, and viruses (4). This procedure localized treatments to a specific 'loop', allowing us to sample this area of the intestine. A significant drawback of this method is the single window of opportunity to administer treatments (i.e. at the time of surgery). Furthermore, samples of both the intestinal mucosa and luminal contents can only be taken at the termination of the project. Other salient limitations of the above model are that the surgical manipulation and requisite post-operative measures (e.g. administration of antibiotics and analgesics) can directly affect the treatment itself and/or alter immune function, thereby confounding results. Therefore, we modified our intestinal loop model by inserting long-term catheters into the loops. Sheep recover fully from the procedure, and are unaffected by the exteriorized catheters. Notably, the establishment of catheters in loops allows us to introduce multiple treatments over an extended interval, following recovery from surgery and clearance of drugs administered during surgery and the post-operative period.

We describe a novel surgical method for catheterizing 'intestinal loops' within the ileum of sheep. Once animals have recovered from surgery and have cleared antibiotics and analgesics, multiple treatments can be deposited directly in loops via the catheters.

Cateterização de alças intestinais em Ruminantes

The intestine is a complex structure that is involved not only in absorption of nutrients, but also acts as a barrier between the individual and the ...

Measurement of the Pressure-volume Curve in Mouse Lungs

In recent decades the mouse has become the primary animal model of a variety of lung diseases. In models of emphysema or fibrosis, the essential phenotypic changes are best assessed by measurement of the changes in lung elasticity. To best understand specific mechanisms underlying such pathologies in mice, it is essential to make functional measurements that can reflect the developing pathology. Although there are many ways to measure elasticity, the classical method is that of the total lung pressure-volume (PV) curve done over the whole range of lung volumes. This measurement has been made on adult lungs from nearly all mammalian species dating back almost 100 years, and such PV curves also played a major role in the discovery and understanding of the function of pulmonary surfactant in fetal lung development. Unfortunately, such total PV curves have not been widely reported in the mouse, despite the fact that they can provide useful information on the macroscopic effects of structural changes in the lung. Although partial PV curves measuring just the changes in lung volume are sometimes reported, without a measure of absolute volume, the nonlinear nature of the total PV curve makes these partial ones very difficult to interpret. In the present study, we describe a standardized way to measure the total PV curve. We have then tested the ability of these curves to detect changes in mouse lung structure in two common lung pathologies, emphysema and fibrosis. Results showed significant changes in several variables consistent with expected structural changes with these pathologies. This measurement of the lung PV curve in mice thus provides a straightforward means to monitor the progression of the pathophysiologic changes over time and the potential effect of therapeutic procedures.

Here we present a protocol to simply and reliably measure the lung pressure-volume curve in mice, showing that it is sufficiently sensitive to detect phenotypic parenchymal changes in two common lung pathologies, pulmonary fibrosis and emphysema. This metric provides a means to quantify the lung&#8217;s structural changes with developing pathology.

Medição da curva pressão-volume no mouse Lungs

In recent decades the mouse has become the primary animal model of a variety of lung diseases. In models of emphysema or fibrosis, the essential ...

Medicina

Cardiac Catheterization in Mice to Measure the Pressure Volume Relationship: Investigating the Bowditch Effect

Animal models that mimic human cardiac disorders have been created to test potential therapeutic strategies. A key component to evaluating these strategies is to examine their effects on heart function. There are several techniques to measure in vivo cardiac mechanics (e.g., echocardiography, pressure/volume relations, etc.). Compared to echocardiography, real-time left ventricular (LV) pressure/volume analysis via catheterization is more precise and insightful in assessing LV function. Additionally, LV pressure/volume analysis provides the ability to instantaneously record changes during manipulations of contractility (e.g., &#946;-adrenergic stimulation) and pathological insults (e.g., ischemia/reperfusion injury). In addition to the maximum (+dP/dt) and minimum (-dP/dt) rate of pressure change in the LV, an accurate assessment of LV function via several load-independent indexes (e.g., end systolic pressure volume relationship and preload recruitable stroke work) can be attained. Heart rate has a significant effect on LV contractility such that an increase in the heart rate is the primary mechanism to increase cardiac output (i.e., Bowditch effect). Thus, when comparing hemodynamics between experimental groups, it is necessary to have similar heart rates. Furthermore, a hallmark of many cardiomyopathy models is a decrease in contractile reserve (i.e., decreased Bowditch effect). Consequently, vital information can be obtained by determining the effects of increasing heart rate on contractility. Our and others data has demonstrated that the neuronal nitric oxide synthase (NOS1) knockout mouse has decreased contractility. Here we describe the procedure of measuring LV pressure/volume with increasing heart rates using the NOS1 knockout mouse model.

This article describes the measurement of murine left ventricular function via pressure/volume analysis at different heart rates.

O cateterismo cardíaco em camundongos para medir o volume Pressão do relacionamento: Investigando o efeito Bowditch

Animal models that mimic human cardiac disorders have been created to test potential therapeutic strategies. A key component to evaluating these ...

Biventricular Assessment of Cardiac Function and Pressure-Volume Loops by Closed-Chest Catheterization in Mice

Assessment of cardiac function is essential to conduct cardiovascular and pulmonary-vascular preclinical research. Pressure-volume loops (PV loops) generated by recording both pressure and volume during cardiac catheterization are vital when assessing both systolic and diastolic cardiac function. Left and right heart function are closely related, reflected in ventricular interdependence. Thus, recording biventricular function in the same animal is important to get a complete assessment of cardiac function. In this protocol, a closed chest approach to cardiac catheterization consistent with the way catheterization is performed in patients is adopted in mice. While challenging, the closed chest strategy is a more physiological approach, because opening the chest results in major changes in preload and afterload that create artifacts, most notably a fall in systemic blood pressure. While high-resolution echocardiography is used to assess rodents, cardiac catheterization is invaluable, particularly when assessing diastolic pressures in both ventricles.
Described here is a procedure to perform invasive, closed chest, sequential left and right ventricular pressure-volume (PV) loops in the same animal. PV loops are acquired using&#160;admittance technology with a mouse pressure-volume catheter and pressure-volume system acquisition. The procedure is described, beginning with the neck dissection, which is required to access the right jugular vein and the right carotid artery, to the insertion and positioning of the catheter, and finally the data acquisition. Then, the criteria required to ensure the acquisition of high-quality PV loops are discussed. Finally, the analysis of the left and right ventricular PV loops and the different hemodynamic parameters available to quantify systolic and diastolic ventricular function are briefly described.

Presented here is a protocol to assess biventricular heart function in mice by generating pressure-volume (PV) loops from the right and left ventricle in the same animal using closed chest catheterization. The focus is on the technical aspect of surgery and data acquisition.

Avaliação Biventricular da Função Cardíaca e Alças Pressão-Volume por Cateterismo Fechado de Tórax em Camundongos

Assessment of cardiac function is essential to conduct cardiovascular and pulmonary-vascular preclinical research. Pressure-volume loops (PV loops) ...

Cardiac Response to &#946;-Adrenergic Stimulation Determined by Pressure-Volume Loop Analysis

Determination of the cardiac function is a robust endpoint analysis in animal models of cardiovascular diseases in order to characterize effects of specific treatments on the heart. Due to the feasibility of genetic manipulations the mouse has become the most common mammalian animal model to study cardiac function and to search for new potential therapeutic targets. Here we describe a protocol to determine cardiac function&#160;in vivo using pressure-volume loop measurements and analysis during basal conditions and under &#946;-adrenergic stimulation by intravenous infusion of increasing concentrations of isoproterenol. We provide a refined protocol including ventilation support taking into account the positive end-expiratory pressure to ameliorate negative effects during open-chest measurements, and potent analgesia (Buprenorphine) to avoid uncontrollable myocardial stress evoked by pain during the procedure. All together the detailed description of the procedure and discussion about possible pitfalls enables highly standardized and reproducible pressure-volume loop analysis, reducing the exclusion of animals from the experimental cohort by preventing possible methodological bias.

Here we describe a cardiac pressure-volume loop analysis under increasing doses of intravenously infused isoproterenol to determine the intrinsic cardiac function and the &#946;-adrenergic reserve in mice. We use a modified open-chest approach for the pressure-volume loop measurements, in which we include ventilation with positive end-expiratory pressure.

Resposta cardíaca à estimulação β-adrenérgica determinada pela análise do loop de pressão-volume

Determination of the cardiac function is a robust endpoint analysis in animal models of cardiovascular diseases in order to characterize effects of ...

Cardiac Pressure-Volume Loop Analysis Using Conductance Catheters in Mice

Cardiac pressure-volume loop analysis is the &#8220;gold-standard&#8221; in the assessment of load-dependent and load-independent measures of ventricular systolic and diastolic function. Measures of ventricular contractility and compliance are obtained through examination of cardiac response to changes in afterload and preload. These techniques were originally developed nearly three decades ago to measure cardiac function in large mammals and humans. The application of these analyses to small mammals, such as mice, has been accomplished through the optimization of microsurgical techniques and creation of conductance catheters. Conductance catheters allow for estimation of the blood pool by exploiting the relationship between electrical conductance and volume. When properly performed, these techniques allow for testing of cardiac function in genetic mutant mouse models or in drug treatment studies. The accuracy and precision of these studies are dependent on careful attention to the calibration of instruments, systematic conduct of hemodynamic measurements and data analyses. We will review the methods of conducting pressure-volume loop experiments using a conductance catheter in mice.

Cardiac pressure-volume loop analysis is the most comprehensive way to measure cardiac function in the intact heart. We describe a technique to perform and analyze cardiac pressure volume loops, using conductance catheters.

Cardiac Pressão-Volume Análise loop usando Conductance Cateteres em Ratos

Cardiac pressure-volume loop analysis is the &#8220;gold-standard&#8221; in the assessment of load-dependent and load-independent measures of ventricular ...

Explorando o desempenho cardíaco dependente de FC usando um protocolo de estimulação atrial

A Pacing-Controlled Procedure for the Assessment of Heart Rate-Dependent Diastolic Functions in Murine Heart Failure Models

Heart failure with preserved ejection fraction (HFpEF) is a condition characterized by diastolic dysfunction and exercise intolerance. While exercise-stressed hemodynamic tests or MRI can be used to detect diastolic dysfunction and diagnose HFpEF in humans, such modalities are limited in basic research using mouse models. A treadmill exercise test is commonly used for this purpose in mice, but its results can be influenced by body weight, skeletal muscle strength, and mental state. Here, we describe an atrial-pacing protocol to detect heart rate (HR)-dependent changes in diastolic performance and validate its usefulness in a mouse model of HFpEF. The method involves anesthetizing, intubating, and performing pressure-volume (PV) loop analysis concomitant with atrial pacing. In this work, a conductance catheter was inserted via a left ventricular apical approach, and an atrial pacing catheter was placed in the esophagus. Baseline PV loops were collected before the HR was slowed with ivabradine. PV loops were collected and analyzed at HR increments ranging from 400 bpm to 700 bpm via atrial pacing. Using this protocol, we clearly demonstrated HR-dependent diastolic impairment in a metabolically induced HFpEF model. Both the relaxation time constant (Tau) and the end-diastolic pressure-volume relationship (EDPVR) worsened as the HR increased compared to control mice. In conclusion, this atrial pacing-controlled protocol is useful for detecting HR-dependent cardiac dysfunctions. It provides a new way to study the underlying mechanisms of diastolic dysfunction in HFpEF mouse models and may help develop new treatments for this condition.

Autor em destaque: investigando a função cardíaca dependente de FC em modelos de camundongos por meio de uma nova abordagem de estimulação atrial 

The present protocol describes obtaining the pressure-volume relationship through transesophageal pacing, which serves as a valuable tool in evaluating diastolic function&#160;in mouse models of heart failure.

Um procedimento de estimulação cardíaca controlada para avaliação das funções diastólicas dependentes da frequência cardíaca em modelos murinos de insuficiência cardíaca