ALCAPA (anomalous left coronary artery from pulmonary artery) syndrome is a rare congenital abnormality that involves an anomalous insertion of the left coronary artery into the pulmonary artery. Ninety percent of patients present in the first year of life with signs and symptoms of heart failure or sudden cardiac death secondary to chronic myocardial ischemia. There have been an increasing number of reports of ALCAPA patients surviving to adulthood. There seems, however, to be a tendency to die suddenly in the third decade of life. Adult survivors are either asymptomatic or present with mitral regurgitation, cardiomyopathy, myocardial ischemia, or malignant arrhythmias. The management of the older patient presenting with symptoms resulting from ischemia and progressive left ventricular dysfunction remains a challenge. Treatment is largely based on guidelines for adult congenital heart disease management and an extrapolation of evidence from heart failure practice. Currently, surgical reimplantation of the anomalous coronary onto the aorta is the mainstay of treatment. The management of heart failure, sudden cardiac death, and ventricular arrhythmia present problems that are not addressed by reimplantation of the anomalous vessel alone. In this report, we present two cases with different modes of presentation and discuss treatment options.

RationaleA quantitative framework to summarize and explain the quasi-stationary population dynamics of unstable phase singularities (PS) and wavelets in human atrial fibrillation (AF) is at present lacking. Building on recent evidence showing that the formation and destruction of PS and wavelets in AF can be represented as renewal processes, we sought to establish such a quantitative framework, which could also potentially provide insight into the mechanisms of spontaneous AF termination.ObjectivesHere, we hypothesized that the observed number of PS or wavelets in AF could be governed by a common set of renewal rate constants λf (for PS or wavelet formation) and λd (PS or wavelet destruction), with steady-state population dynamics modeled as an M/M/∞ birth–death process. We further hypothesized that changes to the M/M/∞ birth–death matrix would explain spontaneous AF termination.Methods and ResultsAF was studied in in a multimodality, multispecies study in humans, animal experimental models (rats and sheep) and Ramirez-Nattel-Courtemanche model computer simulations. We demonstrated: (i) that λf and λd can be combined in a Markov M/M/∞ process to accurately model the observed average number and population distribution of PS and wavelets in all systems at different scales of mapping; and (ii) that slowing of the rate constants λf and λd is associated with slower mixing rates of the M/M/∞ birth–death matrix, providing an explanation for spontaneous AF termination.ConclusionM/M/∞ birth–death processes provide an accurate quantitative representational architecture to characterize PS and wavelet population dynamics in AF, by providing governing equations to understand the regeneration of PS and wavelets during sustained AF, as well as providing insight into the mechanism of spontaneous AF termination.

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