- Oral presentation
- Open Access
An isolated pig heart for the development, validation and translation of novel magnetic resonance techniques
https://doi.org/10.1186/1532-429X-12-S1-O17
© Schuster et al; licensee BioMed Central Ltd. 2010
- Published: 21 January 2010
Keywords
- Cardiac Magnetic Resonance
- Myocardial Perfusion Imaging
- Late Gadolinium Enhancement Imaging
- Magnetic Resonance Technique
- Tesla Magnetic Resonance
Introduction
Novel magnetic resonance (MR) techniques and imaging biomarkers are often validated in small animal models or empirically in patients. The direct translation of small animal cardiac MR imaging protocols to humans is rarely possible, while validation of novel imaging techniques in humans by tracking changes in MR biomarkers in response to externally controlled changes in blood flow, for example, is difficult, or unethical. An isolated blood-perfused pig heart model which closely resembles human physiology, anatomy and size, can be exquisitely controlled in terms of regional blood flow, oxygenation, afterload and workload, and can be imaged by the same equipment used for humans. It would therefore be a valuable tool for the development, validation and translation of novel magnetic resonance techniques.
Purpose
To design and build a novel MR-compatible, explanted, blood-perfused and free-beating pig heart model and test its feasibility at a clinical 3 Tesla MR Scanner.
Methods
A Scheme of the isolated perfusion mode. Starting from the perfusate resevoir (38°C) the perfusate is firstly passed through the roller pump 2 into a dialysis module and further through a blood oxygenator with integrated heat exchanger. The oxygenated blood is then pumped into the heart via roller pump 1. Before entering the heart an air trap removes air bubbles from the perfusate. The dialysate (38°C) is pumped through the dialysis module with a centrifugal pump (pump 3, flow of 51 min -1) to exchange metabolites between the venous perfusate and the dialysate. The dialysate is re-circulated in a resevoir. T: sensor for dialysate temperature: O2 and CO2: valves for oxygen and carbon dioxide input. The perfusate resevoir and the venous and arterial blood circiuts are fully water-jacketed. Termperature is controlled by an external heater. B Detail of the technical setup of the MR compatible perfusion system. All eletrical parts (control-unit, power-supply, pumps, etc) are placed approximately 6 meters distant to the magenet. The pump engines were then connected to the custom made MR compatible pump heads using polycarbon tubes. C Detail Heart Chamber
Measurements and Adjustments of physiological parameters in the isolated pig heart model
Parameter | Assessed by | Controlled by | Experimental setup |
|---|---|---|---|
pO2, pCO2 | Oxygen probe (interstitial) Part. Pressure (ven., art.) | Blood oxygenator, oxygenation of dialysate | Levels of pO2: fully adjustable to induce graded hypoxia Levels of pCo2: Adjusted to pH |
pH | blood gas analysis | CO2 saturation | Constant |
Preload, Afterload | Tip Manometer | Adjustable | |
CPP, CBF | Tip Manometer, Flowmeter | Flow/Afterload | individually for each coronary |
Heart rate | ECG | Pacer | permanent registration |
LVP, RVP | conductance catheter, tip-manometer | Constant (Modified according to the afterload level) | |
Troponin/Myoglobin/Creatine kinase/glucose/lactate | blood samples | Blood Gas Analysis | |
Tissue | EMB (Histology, immunohisto-chemistry, electron microscopy) | ||
(CPP Coronary perfusion pressure, LVP left ventricular pressure, RVP right ventricular pressure, SV stroke volume, dP/dt pressure over time/myocardial contractile function, DTF diastolic time frame, EMB endomyocardial biopsy) |
We tested functional cardiac imaging (CINE), high-resolution perfusion imaging (<2 × 2 mm) using a combination of 3 Tesla, parallel imaging (SENSE) and temporal undersampling (kt), as well as late gadolinium enhancement imaging.
Results
A midventricular short axis view (enddiastolic frame); B midventricular short axis view (endsystolic frame); C kt-SENSE selective Right Coronary Artery (RCA) first pass perfusion (midventricular slice); D Transmural Late Gadolinium Enhancement after 180 munites RCA occlusion indicating myocardial infarction (midventricular slice).
Conclusion
The technical design of an isolated pig heart model allows to represent and image in situ cardiac function ex vivo. This novel system allows for excellent control of physiological parameters, validation against gold standards, and easy translation of the methods to patients using the same equipment and imaging sequences.
Authors’ Affiliations
Copyright
This article is published under license to BioMed Central Ltd.
