TASK DEFINITION: Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.
PROBLEM: Context: Pulmonary vein (PV) isolation is a curative treatment for patients with atrial fibrillation. The aim of this study was to evaluate prospectively the effects of adenosine administration on the PV activity and atrio-venous conduction after PV isolation.', 'Twenty-nine patients (21 m; age: 55+/-8 years) were submitted to ostial PV isolation guided by basket catheter recordings. After successful isolation, the effects of a 12 mg intravenous bolus of adenosine were tested in 62 PVs. In 22/62 PVs (35%), left atrium (LA)-to-PV conduction was transiently (16.6+/-7.1 s, range: 3.8-27.9 s) or permanently (3 PVs) restored in response to adenosine administration. The prevalence of this phenomenon was 39% in left superior PVs, 43% in right superior PVs, and 22% in left inferior PVs (p=0.365). It occurred more frequently in the presence of dissociated PV activity (11/15 PVs, 73% vs. 11/47 PVs, 23%; p=0.002), whereas it was not influenced by the median duration of the radiofrequency current (RFC) delivery for each PV [19 (IQR: 12-26) min vs. 16 (IQR: 11-24) min: p=0.636]. A lengthening or shortening of the LA-PV conduction time was observed at LA-PV conduction appearance and disappearance in 36% and 55% of the cases, respectively. Further RFC applications (median: 5.5 min, IQR: 4-11 min) at the residual conduction breakthrough(s) indicated by the basket catheter recordings definitively eliminated adenosine-induced recovery of LA-PV conduction in all cases. Finally, when present, intrinsic PV discharge was invariably depressed by adenosine administration.
Answer: Adenosine may transiently or permanently re-establish LA-PV conduction after apparently successful PV isolation. This phenomenon is abolished by additional RFC delivery. However, its possible influence on the clinical results of PV ablation must be evaluated by properly designed, randomized studies.

SOLUTION: Does adenosine restore atrio-venous conduction after apparently successful ostial isolation of the pulmonary veins?

PROBLEM: Context: Behavioral studies of spatial navigation in aging indicate that orientation using an allocentric reference frame (object-centered orientation) is impaired, whereas orientation using egocentric processes (self-centered orientation) is not. It has been proposed that navigational deficits may result from more general alterations of perception and attention or executive functions. The purpose of this study is to assess allocentric and egocentric representation in elderly individuals, and to determine if age-related deficits in spatial navigation are related to an attentional decline.', 'We assessed encoding of the position of geometrical shapes, depending specifically on an allocentric or egocentric reference frame, during ERP recording in young and old subjects.', 'Aging was associated with a performance decline in allocentric, but not egocentric, encoding. Both allocentric and egocentric conditions elicited parietal early components P1 and N1, reflecting top-down modulation, and components P2 and N2, reflecting selective attention and stimulus categorization. We observed age-associated effects on N1 and N2 amplitudes and on N2 latency in both spatial conditions. Moreover, impaired allocentric performance in older subjects was associated with a greater P2 amplitude and delayed P2 latency compared with younger subjects.
Answer: These results suggest that elderly individuals present with deficits when spatial orientation relies on allocentric representation, and are associated with age-related deficits in spatial attention.

SOLUTION: Is allocentric but not egocentric orientation impaired during normal aging : an ERP study?

PROBLEM: Context: Nonoperative management of hemodynamically stable patients with blunt hepatic injuries has become the standard of care over the past decade. However, controversy regarding the role of in-hospital follow-up computed tomographic (CT) scans as a part of this nonoperative management scheme is ongoing. Although many institutions, including our own, have advocated routine in-hospital follow-up scans, others have suggested a more selective policy. Over time, we have perceived a low yield from follow-up studies. The hypothesis for this study is that routine follow-up imaging of asymptomatic patients is unnecessary.', 'All patients selected for nonoperative management of blunt hepatic injury were evaluated for utility of follow-up CT scans over a 4-year period.', 'There were 530 stable patients with hepatic injury on admission CT scans in which follow-up scans were obtained within a week of admission. All injuries were classified according to the revised American Association for the Surgery of Trauma Organ Injury Scale: 102 (19.2%) grade I, 181 (34.1%) grade II, 158 (29.8%) grade III, 74 (13.9%) grade IV, and 15 (2.8%) grade V. Follow-up scans showed that most injuries were either unchanged (51%) or improved (34.7%). Only three patients underwent intervention based on their follow-up scans: two patients had arteriography (one with therapeutic embolization) and one had percutaneous drainage. Each of those patients had clinical signs or symptoms that were indicative of ongoing hepatic abnormality.
Answer: These data demonstrate that, regardless of injury grade, routine in-hospital follow-up scans are not indicated as part of the nonoperative management of blunt liver injuries. Follow-up scans are indicated for patients who develop signs or symptoms suggestive of hepatic abnormality.

SOLUTION:
Is routine follow-up imaging unnecessary in the management of blunt hepatic injury?