Intracoronary electrocardiogram.

SEE PAGE 988 A nimal studies on the intracoronary electrocardiogram (IC ECG) preceded coronary angioplasty, today referred to as percutaneous coronary intervention (PCI), by 1 year, almost 40 years ago (1). Even the balloon was there, but it was used for temporary coronary occlusion producing ischemia rather than for treating coronary stenoses. In 1983, pacemaker electrodes were used to derive an intracardiac ECG in patients with various degrees of ischemia (2). In 1984, IC ECG was first used in patients. This happened in the realm of PCI (3). When hooking up the coronary guidewire to equipment for coronary pacing to obviate the need for a temporary right ventricular pacemaker, it was found that simultaneous connection to the precordial input socket of any ECG machine revealed a continuous I.C. ECG (4). This not only reflected by definition the territory of interest but also showed ischemia much more conspicuously (and therefore conceivably sooner) than even the precordial leads. The I.C. ECG appeared particularly helpful in the territory of a nondominant left circumflex coronary artery, notoriously poorly represented by standard ECG leads (Figure 1). These findings were confirmed in further clinical papers (5–7). The poor representation of the territory of the left circumflex coronary artery in the traditional 12-lead ECG (Figure 1) was again highlighted in 1989 when the I.C. ECG was examined in the role of the gold standard for regional myocardial ischemia during PCI. The I.C. ECG excelled indeed due to the unfavorable traditional external lead position. Ischemia in the I.C. ECG, but not in the traditional leads, was identical in