In vivo evidence of coronary artery vasospasm in Sur2^–/– mice. (a–f) Representative telemetric ECG recording of a 12-week-old male Sur2^–/– mouse. Each of the serial tracings reflects 1.5 seconds of the entire 160-second episode. The timing of each 1.5-second segment with respect to the duration of the entire episode is indicated in seconds below the tracing. (a) A baseline tracing at the beginning of the event. (b and c) Marked ST segment elevation that occurs within 30 seconds. ST segment elevation leads to atrioventricular heart block seen in d. Following the acute injury pattern of ST segment elevation, ST segment depression was present during recovery (e). (f) A return to baseline ECG readings. (g) Continuous ECG recording capturing sudden death. Upper tracing depicts heart rate and bradycardia events (downward spikes) over a 17-hour period. Individually, numbered regions are magnified in the lower three sets of ECG waveform tracings indicating: 1, normal rate and rhythm; 2, post-ST elevation atrioventricular heart block with bradycardia; 3, agonal rhythm with a widened QRS.