Biomedical subjects

Nicola Bruno

Publications and source records attributed to Nicola Bruno.

15 recordsLinked to original sources

PubMed2006

A visual-haptic Necker cube reveals temporal constraints on intersensory merging during perceptual exploration.

When viewing a three-dimensional Necker cube with one eye, participants can experience illusory reversals even while they feel the cube with their hands. This surprising property of the visual-haptic Necker cube affords a unique opportunity to investigate temporal constraints on interactions between vision and touch during extended observation of a three-dimensional object. Our observers reported reversals while they viewed the cube and, at the same time, they either held it with two-finger grips, felt it with while their hands remained stationary, or actively explored it by moving one hand. Consistent with a multisensory approach to three-dimensional form perception, touch had a clear effect on both the number and the duration of illusory percepts. Additionally, when observers alternated between stationary and moving periods during exploration, transitions from stationary to moving-hand haptics played a crucial role in inhibiting illusory reversals. A temporal analysis of the probability of first reversals occurring after different types of motor transition revealed a "vetoing window" initiating approximately 2s after the transition and lasting at least another 1-2s. Implications for multisensory processes during exploration are discussed.

Form Perception↗

PubMed2006

Low clinical recurrence and procedure benefits following treatment of common atrial flutter by electrogram-guided hot spot focal cryoablation.

BACKGROUND: The study sought to evaluate whether electrogram-aided identification of hot spot targets produces additional clinical and/or procedure benefits when using a non-traditional focal cryo ablation method to treat common atrial flutter. METHODS: A preliminary study identified a specific electrogram criterion (e.g., a stimulus to onset of electrogram time of 74 [+/- 5] ms) that produced successful cryo testing plus subsequent cryoablation with demonstrable bi-directional isthmus block created at intervention site. In the present study, 26 consecutive patients with symptomatic common atrial flutter were ablated with a 9FR 8 mm tip cryo catheter using electrogram-aided identification of hot spot targets with a stimulus to onset of electrogram time of > or =70 ms. Outcomes measured were bi-directional isthmus block at intervention, symptom and conduction recurrence at 3 month follow-up, symptom recurrence at 6 month follow-up, and procedure characteristics. RESULTS: Acute success rate at intervention was 100%. The percentage of patients with symptom recurrence by 3 month follow-up was 4.5% and no additional patients had arrhythmia symptoms documented by 12 month follow-up. Repeat electrophysiological study (EPS) at 3 month follow-up identified 44% of patients with conduction recurrence. The mean +/- SD number of cryo tests and ablations were 11 +/- 9 and 2 +/- 1, respectively. Procedure, fluoroscopy and cryoapplication times were 77 +/- 29 min, 11 +/- 7 min, and 28 +/- 11 min, respectively. CONCLUSIONS: A high acute success rate, plus low long-term clinical recurrence rate and procedure benefits may be achieved with electrogram-aided identification of hot spots for focal cryo ablation treatment of common atrial flutter using a 9FR 8 mm tip cryo catheter. The population of patients who were asymptomatic and had demonstrated conduction recurrence on repeat EPS at 3 month follow-up require close scrutiny over the long-term to ascertain whether they eventually experience arrhythmic symptoms. However, should these patients remain symptom-free over the long-term it would suggest that the entire isthmus may not be needed to support symptomatic common atrial flutter.

Atrial Flutter↗

PubMed2006

Ames's window in proprioception.

When holding a small-scale model of Ames's trapezoidal window with the arms fully extended, several observers experience a striking proprioceptive distortion (eg one hand appears farther from the other, or one arm appears longer than the other). However, data from a matching experiment suggest that the proprioceptive misalignment of the hands is, in fact, rather less than the apparent slant of the window when this is not held. This finding argues against a 'visual-capture' account, supports an explanation in terms of bimodal integrative processes, and underscores the importance of supplementing phenomenological observations with objective measures.

Arm↗

PubMed2005

Long-term efficacy of cryo catheter ablation for the treatment of atrial flutter: results from a repeat electrophysiologic study.

OBJECTIVES: We investigated the long-term efficacy of cryo ablation for treatment of atrial flutter. BACKGROUND: To our knowledge, no study has assessed the long-term efficacy of cryo ablation by assessing both symptom and conduction recurrence. METHODS: A total of 45 consecutive patients with symptomatic atrial flutter were ablated with a 7-F, 6-mm-tip, quadripolar cryo catheter (Freezor Xtra, CryoCath Technologies Inc., Kirkland, Canada). Electrophysiologic studies (EPS) were performed with diagnostic catheters. Cryo ablation was at -75 degrees C for 4 min, beginning at the inferior rim of the coronary sinus os and creating a posterior line to the Eustachian ridge. Safety, bi-directional isthmus block at intervention, and recurrence at three, six, and nine months post procedure were assessed. RESULTS: There were no adverse events reported. All patients were free of discomfort on cryo energy delivery. The acute success rate at intervention was 87%. Follow-up data from 39 acutely successful patients showed 27 (69%) without conduction recurrence on repeat EPS at three months, and none (0%) had symptom recurrence documented by Holter monitoring, electrocardiogram, and/or patient diary records at three, six, and nine months follow-up. CONCLUSIONS: Our experience with a new 7-F, 6-mm-tip, quadripolar cryo catheter yielded a fairly high success rate at intervention, an excellent safety profile, and a good chronic success rate in terms of symptom recurrence. However, further monitoring is necessary to determine whether all asymptomatic patients continue to remain free of symptoms, given the small pool of patients demonstrated to have conduction recurrence.

Aged↗

PubMed2005

Comparison between a 7 French 6 mm tip cryothermal catheter and a 9 French 8 mm tip cryothermal catheter for cryoablation treatment of common atrial flutter.

BACKGROUND: Larger tipped cryothermal catheters may deliver efficacy and procedure benefits in the treatment of patients with atrial flutter. OBJECTIVE: To compare 7 French 6 mm and 9 French 8 mm tip cryothermal catheters (Freezor, Xtra or Freezor, MAX, CryoCath Technologies Inc., Kirkland, Canada) in terms of acute and chronic efficacy, and procedure characteristics in the treatment of atrial flutter. METHODS: This non-randomized clinical investigation determined bi-directional isthmus block at intervention, procedure characteristics, and symptom and conduction recurrence rates post procedure in consecutive patients with symptomatic atrial flutter ablated either with the 7 French 6 mm tip cryothermal catheter (n = 43) at -75 degrees C for 4 minutes or the 9 French 8 mm tip cryothermal catheter (n = 51) at -75 degrees C for 8 minutes. RESULTS: Clinical data showed a higher acute success rate for the larger tipped catheter (100% vs. 88%). Symptom recurrence rates were 0% for both catheters at 3, 6, and 9 month follow-up. Conduction recurrence rates were similar for both catheters on repeat electrophysiological study at 3 months post procedure (35% vs. 32%). Procedure benefits were fewer cryotests (20 +/- 17 vs. 26 +/- 21) and ablations (4 +/- 4 vs. 12 +/- 18), and shorter procedure (80 +/- 61 min vs. 87 +/- 48 min), fluoroscopy (14 +/- 9 min vs. 24 +/- 10 min), and cryoapplication times (37 +/- 18 min vs. 44 +/- 23 min) with the larger tipped catheter. There were no adverse events reported. CONCLUSIONS: Clinical results showed differences in catheter performance that favoured the larger tipped catheter. However, increased acute success rate did not translate into reduced conduction recurrence rate post ablation, although clinical recurrence was completely absent long-term.

Adult↗

PubMed2005

Cryothermal ablation treatment of atrial flutter--experience with a new 9 French 8 mm tip catheter.

BACKGROUND: Cardiac cryoablation has been used to successfully treat a variety of arrhythmias. OBJECTIVE: This study documents our experience with a new 9 French (FR) 8 mm cryocatheter for ablation treatment of symptomatic atrial flutter. METHODS: A total of 77 consecutive patients with symptomatic atrial flutter were treated. Electrophysiological studies (EPS) were performed with diagnostic catheters and ablation was performed with a 9FR, 8 mm tip, quadripolar cryocatheter (Freezor MAX catheter, CryoCath Technologies Inc., Kirkland, Canada). Cryoablation at -75 degrees C for 8 minutes was performed, beginning at the inferior rim of the coronary sinus (CS) os and creating a posterior line to the Eustachian ridge. Safety, bidirectional isthmus block at intervention, and recurrence at 3 months post procedure were assessed. RESULTS: There were no adverse events reported. All patients remained free of discomfort on cryoenergy delivery. The acute success rate at intervention was 96% for all patients and 100% for those with common atrial flutter. Follow-up data from 47 patients showed 33 (70%) patients without conduction recurrence on repeat EPS at 3 months. Although, 1 (2%) patient had both symptom and conduction recurrence. Data available from 53 acutely successful patients at 6 month clinical follow-up showed that 48 (91%) patients were asymptomatic and 5 (9%) patients had recurrence documented by ECG and/or patient diary records. CONCLUSIONS: Our experience with a new 9FR, 8 mm tip, quadripolar cryocatheter yielded a high success rate at intervention and an excellent safety profile. Although repeat EPS at 3 months post ablation identified conduction recurrence in 30% of patients, at 6 month clinical follow-up only 9% of patients had recurrence. Further monitoring is necessary to assess whether the relatively low recurrence rate observed at 6 month clinical follow-up is maintained over the long term.

Atrial Flutter↗

PubMed2005

Unifying sequential effects in perceptual grouping.

Temporally-extended perception involves a delicate balance of constancy and change. 'This can be seen, for instance, when viewing bistable figures such as the Necker cube. A recent study by Gepshtein and Kubovy of sequential effects in multistable dot lattices demonstrates constancy and change within the same set of data. They propose that these opposing trends might be explained by the same single factor: a persistent random orientation bias that is intrinsic to brain activity. This proposal could form the basis for a new account of multistability.

Cognition↗

PubMed2004

How does action resist visual illusion? Uncorrected oculomotor information does not account for accurate pointing in peripersonal space.

Using spatially identical displays (variants of the Müller-Lyer illusion), we compared the accuracy of spatial verbal judgments with that of saccadic (eye) and pointing (hand) movements. Verbal judgments showed a clear effect of the illusion. The amplitude of the primary saccade from one endpoint of the pattern (at fixation) to the other also showed an effect of the illusion. Conversely, movement amplitudes when pointing from one endpoint (initial finger position) to the other were significantly more accurate than both saccades and verbal responses. In a control experiment in which the viewing conditions between the saccade and pointing experiments were equalized, saccade amplitude was again affected by the illusion. In several studies, systematic biases in conscious spatial judgments have been contrasted with accurate open-loop pointing in peripersonal space. It has been proposed that such seeming dissociations between vision-for-action and vision-for-consciousness might in fact be because of a simple oculomotor strategy: saccade to the target before it disappears, then use the efference copy of the (accurate) saccadic movement to drive pointing. The present data do not support the hypothesis in this simple form.

Eye Movements↗

PubMed2004

Illusory surfaces affect the integration of local motion signals.

A 2IFC paradigm was used to measure speed discrimination thresholds for pairs of Gabor patches. When one of these patches was phenomenally placed over an illusory surface (IS), we observed higher thresholds relative to control conditions without ISs. Additional controls demonstrated that this effect was due to the placement of the patch on a different phenomenal depth plane rather than to the mere presence of an IS. We conclude that (i) ISs can affect the long-range integration of local motion signals, and (ii) long-range motion integration obeys a coplanarity principle.

Depth Perception↗

PubMed2004

Implantable loop recorders: a novel method to judge patient perception of atrial fibrillation. Preliminary results from a pilot study.

INTRODUCTION: At the present time, several techniques are used or are under investigation for atrial fibrillation (AF) therapy. Nowadays, no well-defined target for such therapies has been yet completely identified. Furthermore, AF is an arrhythmia with high rates of recurrences, both symptomatic and asymptotic. Thus the measure of therapy success rates not only based on symptom perception remains a goal to be reached. AIMS OF THE STUDY: This study investigates the role of an implantable loop recorder (ILR) as an additional tool to identify initiating and perpetuating mechanisms of AF. The role of right atrial linear ablation (RALA) procedures is also investigated using the monitoring capabilities of the ILR. METHODS AND RESULTS: Nine patients (mean age 63.8 +/- 5.9) with paroxysmal AF were referred to our institution as candidates for AF ablation. All patients (pts) had in their medical history several years of AF episodes. Therefore pts were aware of AF related symptoms. Six of them were implanted with an ILR before ablation and were monitored one month before and six months after the procedure. The ILRs stored 54 patient activated events (PAE) and 124 automatically activated events (AAE). 68% of PAEs and 67% of AAEs were classified as appropriate. Most common reasons for inappropriate detections were premature atrial or ventricular contractions among PAEs and undersensing among AAEs. The arrhythmia onset was properly identified in 4 pts (44%). The average AF recurrence rate was 10.8 +/- 3.5 ep/month before ablation and 5.0 +/- 1.8 ep/month after the procedure ( p = 0.042). CONCLUSION: The ILR may be a helpful tool in monitoring pts undergoing ablation. Dedicated AF detection characteristics could give additional value to the device. RALA appears as a feasible, safe and relatively effective first approach in AF therapy.

Aged↗

PubMed2004

Amodal completion in visual search: preemption or context effects?

In a previous study, search for a notched-disk target abutting a square among complete-disk nontargets and squares was inefficient in 250-ms exposures, but relatively efficient in 100-ms exposures. This finding was interpreted as evidence that amodal completion proceeds through a mosaic and then a completion stage, with the latter preempting the former. We used the same target but changed its context: Nontargets were instead notched disks near squares. Task set was also different: Participants searched for a complete disk. Contrary to the prediction of the preemption model, search was efficient in the 100-ms condition and inefficient in the 250-ms condition. We propose that in both the present and the previous studies, the target was ambiguous, and task set and context affected how it was perceived. In both experiments, set effects were evident for 100-ms exposures; context effects were evident for 250-ms exposures.

Affect↗

PubMed2003

When does action resist visual illusions? Effector position modulates illusory influences on motor responses.

Actors viewed horizontal segments either in isolation or embedded in patterns that produce spatial illusory effects (Kanizsa's compression illusion and the "dumbbell" version of the Müller-Lyer compression-expansion illusion). They were asked to reproduce the apparent horizontal extent of these segments by the amplitude of open- or closed-loop motor responses (after having positioned a finger on position A, choose a position B on the right of A such that apparent width = B-A). A touchmonitor was used to present the displays and to record movement amplitudes and times. In open-loop motor responses, displays were turned off as soon as actors raised their finger from position A. In closed-loop responses, displays could be viewed continuously during the actions. Four conditions were investigated: (1). open-loop responses starting from A at the right endpoint of the segment; (2). closed-loop responses from A at the right endpoint of the segment; (3). open-loop responses from A at the left endpoint of the segment; and (4). open-loop responses from A aligned horizontally with the left endpoint of the segment but displaced vertically below that segment. With both kinds of display, results in conditions (1). and (2). demonstrated illusory effects comparable to those measured in standard visual matching experiments, whereas results in conditions (3). and (4). showed essentially no illusory effects. Implications for models of visuomotor transformations in peripersonal space are discussed.

Adult↗

PubMed2003

Measuring surface achromatic color: toward a common measure for increments and decrements.

Surface color is traditionally measured by matching methods. However, in some conditions, the color of certain surfaces cannot be measured: The surface simply looks brighter or darker than all the patches on a matching scale. We studied the reliability, validity, and range of application of three different types of simulated Munsell scales (white-, black-, and split-surrounded) as methods for measuring surface colors in simple disk-ring displays. All the scales were equally reliablefor matching both increments and decrements, but about 2096 of the increments were unmatchable on the white-surrounded scale, about 1396 of the decrements were unmatchable on the black-surrounded scale, and about 9% of the increments were unmatchable on the split-surrounded scale. However, matches on all the scales were linearly related. Therefore, it is possible to convert them to common units, using regression parameters. These units provide an extended metric for measuring all increments and decrements in the stimulus space, effectively removing ceiling and floor effects, and providing measures even for surfaces that were perceived as out of range on some of the scales.

Algorithms↗

PubMed2002

Dissociating perception and action in Kanizsa's compression illusion.

When a horizontally elongated surface is occluded in the middle by a larger surface, it appears narrower than its true width (Kanizsa's compression illusion). We report that a similar compression effect occurs for closed-loop visuomotor matches of size, but not for otherwise comparable open-loop "mimed" reaching or size-matching visuomotor responses. Our study is the first in which a comparison of size perception in personal space with bilateral actions performed with both hands (instead of precision grips employing the thumb and the index finger) is used to investigate motor responses to Kanizsa's compression illusion. Implications for the current debate on the existence of dissociations between spatial perception and visually controlled actions in personal space are discussed.

Adult↗

PubMed2002

Coronary vasospasm and aborted sudden death treated with an implantable defibrillator and stenting.

In selected patients suffering from variant angina, an implantable cardioverter-defibrillator (ICD) and coronary stenting can be helpful to prevent sudden death and treat coronary artery spasm. We report a case of a 47-year-old woman suffering from variant angina, who experienced an episode of ventricular fibrillation promptly cardioverted. After coronary angiography documentation of a mild atherosclerosis, an ICD was implanted and oral nitrates and calcium antagonists were prescribed. The recurrence of chest pain and palpitations prompted us to perform a second coronary angiography that documented a focal coronary artery spasm successfully treated with stent implantation. No other episodes of angina or ventricular arrhythmia were documented during the following 6 months of follow-up.

Angina Pectoris, Variant↗