Survival may be enhanced and transfer for revascularization facilitated when community hospitals use both thrombolysis and IABP to treat patients with acute MI complicated by cardiogenic shock.
Background
The purpose of this study was to examine the spatial resolution of unipolar atrial pace mapping by pacing at adjacent sites within the coronary sinus and the right atrium.
Methods and Results
Unipolar pacing from each pole of a quadripolar catheter was performed in the coronary sinus (n=29) and in the right atrium (n=10). Pacing from the distal electrode was used to simulate the site of origin of an atrial tachycardia. These P waves were compared with the P waves generated by unipolar pacing from each of the three proximal electrodes. The P waves were analyzed for changes in amplitude, duration, and configuration. Pacing within the coronary sinus resulted in significant changes in amplitude and duration at distances of 17 and 21 mm from the distal pole, respectively. Similarly, pacing in the right atrium resulted in significant changes in amplitude and duration at distances of 17 and 32 mm from the distal pole, respectively. No significant changes in configuration were noted in the coronary sinus in any lead at pacing sites ≤32 mm from the distal pole. Configurational changes were noted in the right atrium at pacing sites 17 mm from the distal pole.
Conclusions
The spatial resolution of unipolar atrial pace mapping is ≈17 mm. These findings indicate that mapping techniques that depend on the accurate discrimination of P-wave morphology, such as pace mapping or concealed entrainment, are likely to be imprecise when used in the atria.
Unstable angina is one of the most common reasons for hospital admission in the United States and causes substantial morbidity and mortality. Diagnosis of unstable angina is complicated by the dynamic range of presentations, which can vary between atypical chest pain and acute myocardial infarction. Overcautious management can result in unnecessary hospital admission, whereas inappropriate conservative strategies can cause cardiac injury and death. To define treatment strategies for these patients, the US Agency for Health Care Policy and Research in March 1994 published guidelines on the diagnosis and management of unstable angina. The emphasis is on diagnosis or exclusion of coronary artery disease, establishment of the patient's risk for adverse outcome, and triage to the most appropriate treatment regimen. The guidelines emphasize the use of aspirin, heparin sodium, nitroglycerin, and [3-blockers as the core therapy. Appropriate strategies are reviewed, starting with intensive medical management and ending with patient care after discharge. Many physicians will probably modify their approach to the diagnosis and treatment of unstable angina on the basis of these new guidelines.
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