Hemodynamic Services

The approach used to evaluate hemodynamics in mice will generally be related to the empirical question under consideration. For example, relatively simple questions involving the presence of blood pressure anomalies, such as hypertension or hypotension, in a particular mouse model, might only require placement of a 1.4F micromanometer catheter into the carotid, central aortic arteries, or external jugular. From the obtained arterial pressure recording measures of peak systolic, end-diastolic, and mean arterial pressure can be determined, as well as heart rate.

If the empirical question relates to issues of basal function of the left ventricle (LV), such as inotropic state (contractility), or lusitropic state (relaxation), left ventricular catheterization is appropriate. From LV pressure recordings indexes related to contractility (LV peak pressure, peak +dP/dt) can be derived, as well as indexes of LV passive (LV end-diastolic pressure) and LV active relaxation (Peak –dP/dt, tau).

Suspected derangements in LV contractile and/or adrenergic reserve in genetically altered mice can be evaluated by LV catheterization and simultaneous infusion of selected inotropic agents, such as dobutamine. The function-infusion curves generated with this procedure can reveal defects in contractile reserve related to alterations in metabolic and/or signaling processes.

In situations in which apparent changes in LV function are suspected to be significantly masked or influenced by altered loading conditions, obtaining LV pressure-volume loops using a 1.4F conductance-catheter system may be advisable. Pressure-volume loops obtained under either static basal or dynamic conditions allow for the calculation of additional measures of cardiac performance such as cardiac output, work, power; load-independent measures of function such as maximum elastance, the slope of the end-systolic pressure-volume relationship, arterial elastance and preload recruitable stroke-work; as well as passive LV chamber compliance. Load-independent measures can be especially valuable when testing interventions that provoke alterations in load that might significantly confound the assessment of cardiac function.

Service and data output details

A Scisense instrument system with customized programs is used for analyzing hemodynamic parameters in mice. The catheter is either routinely placed into the left ventricle through the right carotid artery or the right ventricle through the external jugular vein. We can catheterize mice as small as 16 grams. With careful catheter placement, maintenance of basal temperatures and good heart rates we are able to obtain measurements of LVEDP, HR, and dp/dt.

Hemodynamics I

Includes surgical cut down, catheter placement, and recording of aortic or RV pressures only.

Data provided at study end: Spreadsheet with aortic systolic and diastolic pressure measurements and heart rate.

Hemodynamics II

Includes surgical cut down, Scisense catheter placement in left ventricle, recording of LV or RV pressures and derivation of LV or RV peak pressures, LV or RV end-diastolic pressure, ± dp/dt, and tau.

Data provided at study end: Spreadsheet with measurements of various LV or RV pressure-derived hemodynamic variables, including Heart Rate, LV or RV peak pressure, LV or RV end diastolic pressure, Peak +dP/dt, Peak –dP/dt, and tau. A customized spreadsheet is also available.

Hemodynamics III

Hemodynamics III includes surgical cut down, Scisense catheter placement into left ventricle and recording of LV pressure under multiple physiologic conditions such as pre-post pharmacologic interventions, plus derivation of standard indices of LV function for each condition.

Data provided at study end: Spreadsheet with various LV pressure-derived variables assessed at different time points and/or under different physiological conditions. The spreadsheet will include Heart Rate, LV peak pressure, LV end diastolic pressure, Peak +dP/dt, Peak –dP/dt, and tau. A customized spreadsheet is also available.

Hemodynamics IV

Includes surgical cut down, Scisense pressure-volume catheter placement into the left ventricle and recording of LV pressures and volumes under multiple physiologic conditions. Analysis includes derivation of indexes of LV function derived from simultaneous LV pressure-volume recordings (load-independent measurements).

Data provided at study end: Spreadsheet with various LV PV-derived variables assessed at different time points and/or under different physiological conditions. A customized spreadsheet is also available.

Organ harvest post hemodynamic study

Includes simple histo prep of weighing heart, slicing tissue, and preserving in formalin or liquid nitrogen.

Data provided at study end: Spreadsheet which provides mouse weight at time of surgery, mouse weight at time of organ harvest, whole heart weight, LV weight, RV weight, and LV/end BW ratio.

 

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