201Tl and 99mTc-MIBI Retention in an Isolated Heart Model of Low-Flow Ischemia and Stunning: Evidence of Negligible Impact of Myocyte Metabolism on Tracer Kinetics

Adey Ayalew; Pierre-Yves Marie; Patrick Menu; Paul-Michel Mertes; Sandra Audonnet; Valérie Jouan; Pierre Olivier; Gilles Karcher; Dan Ungureanu-Longrois; Alain Bertrand

Article Figures & Data

Figures

Tables

Download figure
Open in new tab
Download powerpoint
FIGURE 1.
Variations in systolic contraction pressure (A) and coronary flow rates (B) between onset and end of experiments conducted in normoxia (○; n = 16), low-flow ischemia (•; n = 15), and stunning (; n = 15).
Download figure
Open in new tab
Download powerpoint
FIGURE 2.
Comparison of activity in interstitial fluid for ²⁰¹Tl (A) and MIBI (B) during experiments conducted in normoxia (□; n = 16), low-flow ischemia (▪; n = 15), and stunning (▨; n = 15). Activities expressed as a fraction of total injected activity per milliliter of interstitial fluid for each of 4 consecutive 10-min periods following myocardial extraction of tracer. *P < 0.05.
Download figure
Open in new tab
Download powerpoint
FIGURE 3.
Comparison of tracer concentration ratios between interstitial (Ci [g⁻¹]) and cellular (Cc [g⁻¹]) spaces for ²⁰¹Tl (A) and MIBI (B) during experiments conducted in normoxia (□; n = 16), low-flow ischemia (▪; n = 15), and stunning (▨; n = 15). Activity ratios determined for each of 4 consecutive 10-min periods following myocardial extraction of tracer. *P < 0.05.
Download figure
Open in new tab
Download powerpoint
FIGURE 4.
Comparison of average tracer myocardial retention fractions for ²⁰¹Tl (A) and MIBI (B) during experiments conducted in normoxia (□; n = 16), low-flow ischemia (▪; n = 15), and stunning (▨; n = 15). Fractions calculated for each of 4 consecutive 10-min periods following myocardial extraction of tracer. *P < 0.05.

Tables

Figures

View popup

TABLE 1

Hemodynamic and Oximetric Parameters in Experiments Performed in Normoxia, Low-Flow Ischemia, and Stunning

		Normoxia (n = 16)	Low-flow ischemia (n = 15)	Stunning (n = 15)
Left ventricular pressure (mm Hg)
Systolic	O	106 ± 16^*†	77 ± 16	68 ± 15
	E	99 ± 18^*	70 ± 16^†	98 ± 18^*
Diastolic	O	7 ± 4	6 ± 5	8 ± 3
	E	7 ± 6	9 ± 7	9 ± 3
Mean	O	51 ± 9^*†	37 ± 5	35 ± 7
	E	44 ± 7^*	33 ± 9^†	43 ± 8^*
Coronary circulation
Flow (mL · min⁻¹ · g⁻¹)	O	5.9 ± 1.8^*†	2.7 ± 0.9^†	4.0 ± 1.6^*
	E	5.6 ± 1.5^*	2.7 ± 1.1^†	4.8 ± 1.8^*
Pressure (mm Hg)	O	78 ± 7^*†	40 ± 9^†	90 ± 16^*
	E	89 ± 22^*	51 ± 25^†	93 ± 20^*
Oxygen extraction (cm³ · mL⁻¹)	O	0.05 ± 0.02^*	0.08 ± 0.01^†	0.06 ± 0.02^*
	E	0.05 ± 0.02^*†	0.08 ± 0.01	0.07 ± 0.02
Oxygen consumption (cm³ · min⁻¹ · g⁻¹)	O	0.31 ± 0.07^*†	0.21 ± 0.06	0.25 ± 0.09
	E	0.30 ± 0.07^*	0.21 ± 0.08^†	0.35 ± 0.11^*

↵* P < 0.05 vs. low-flow ischemia.
↵† P < 0.05 vs. stunning.
O = onset of 40-min period of tracer kinetics analysis; E = end of 40-min period of tracer kinetics analysis.

View popup

TABLE 2

First-Pass Kinetics Parameters in Experiments Performed in Normoxia, Low-Flow Ischemia, and Stunning

	Normoxia (n = 16)	Low-flow ischemia (n = 15)	Stunning (n = 15)
Permeability-surface area product (mL · min⁻¹ · g⁻¹)
²⁰¹TI	10.5 ± 2.0^*†	5.6 ± 2.0^†	7.5 ± 2.5^*
MIBI	3.9 ± 0.8^*†	2.5 ± 0.8^†	3.2 ± 0.9^*
Peak extraction fraction (E_peak)
²⁰¹TI	0.83 ± 0.04^*	0.87 ± 0.02	0.85 ± 0.04
MIBI	0.49 ± 0.10^*	0.59 ± 0.11	0.55 ± 0.11
Net extraction fraction (E_net)
²⁰¹TI	0.73 ± 0.05^*	0.79 ± 0.03	0.77 ± 0.05
MIBI	0.38 ± 0.10^*†	0.48 ± 0.09	0.48 ± 0.11
Mean retention fraction
²⁰¹TI	0.50 ± 0.14^*†	0.63 ± 0.09	0.59 ± 0.10
MIBI	0.31 ± 0.09^*†	0.45 ± 0.10	0.41 ± 0.12
Mean fractional escape rate (min⁻¹)
²⁰¹TI (×10²)	1.5 ± 0.7^*†	0.8 ± 0.4	0.8 ± 0.5
MIBI (×10²)	1.0 ± 0.9^*†	0.3 ± 0.3	0.3 ± 0.3