Surgical Placement of Catheters for Long-term Cardiovascular Exercise Testing in Swine

Daphne P M De Wijs-Meijler; Kelly Stam; Richard W B van Duin; Annemarie Verzijl; Irwin K Reiss; Dirk J Duncker; Daphne Merkus

doi:10.3791/53772

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Method Article

Surgical Placement of Catheters for Long-term Cardiovascular Exercise Testing in Swine

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DOI:

10.3791/53772

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February 9th, 2016

Daphne P M De Wijs-Meijler^*¹ , Kelly Stam^*² , Richard W B van Duin¹ , Annemarie Verzijl² , Irwin K Reiss³ , Dirk J Duncker² , Daphne Merkus²

¹Experimental Cardiology and Neonatology, Erasmus MC, ²Experimental Cardiology, Erasmus MC, ³Neonatology, Erasmus MC

^* These authors contributed equally

Summary

Here we present a protocol to assess cardiopulmonary function in awake swine, at rest and during graded treadmill exercise. Chronic instrumentation allows for repeated hemodynamic measurements uninfluenced by cardiodepressive anesthetic agents.

Abstract

This protocol describes the surgical procedure to chronically instrument swine and the procedure to exercise swine on a motor-driven treadmill. Early cardiopulmonary dysfunction is difficult to diagnose, particularly in animal models, as cardiopulmonary function is often measured invasively, requiring anesthesia. As many anesthetic agents are cardiodepressive, subtle changes in cardiovascular function may be masked. In contrast, chronic instrumentation allows for measurement of cardiopulmonary function in the awake state, so that measurements can be obtained under quiet resting conditions, without the effects of anesthesia and acute surgical trauma. Furthermore, when animals are properly trained, measurements can also be obtained during graded treadmill exercise.

Flow probes are placed around the aorta or pulmonary artery for measurement of cardiac output and around the left anterior descending coronary artery for measurement of coronary blood flow. Fluid-filled catheters are implanted in the aorta, pulmonary artery, left atrium, left ventricle and right ventricle for pressure measurement and blood sampling. In addition, a 20 G catheter is positioned in the anterior interventricular vein to allow coronary venous blood sampling.

After a week of recovery, swine are placed on a motor-driven treadmill, the catheters are connected to pressure and flow meters, and swine are subjected to a five-stage progressive exercise protocol, with each stage lasting 3 min. Hemodynamic signals are continuously recorded and blood samples are taken during the last 30 sec of each exercise stage.

The major advantage of studying chronically instrumented animals is that it allows serial assessment of cardiopulmonary function, not only at rest but also during physical stress such as exercise. Moreover, cardiopulmonary function can be assessed repeatedly during disease development and during chronic treatment, thereby increasing statistical power and hence limiting the number of animals required for a study.

Introduction

Adequate cardiopulmonary function is essential to supply the body with oxygen and nutrients, particularly during conditions of increased metabolic demand such as during exercise¹. The cardiopulmonary response to exercise is characterized by a number of adaptations in cardiac function, i.e., an increase in heart rate, contractility and stroke volume, and microvascular function, i.e., vasodilation in the vascular beds supplying exercising muscles as well as in the pulmonary vasculature, and vasoconstriction in the vascular beds supplying the gastrointestinal system as well as inactive muscles¹. Impaired exercise capacity is an ear....