Perceptual axioms are irreconcilable with Euclidean geometry.

There are different definitions of axioms, but the one that seems to have general approval is that axioms are statements whose truths are universally accepted but cannot be proven; they are the foundation from which further propositional truths are derived. Previous attempts, led by David Hilbert, to show that all of mathematics can be built into an axiomatic system that is complete and consistent failed when Kurt Gödel proved that there will always be statements which are known to be true but can never be proven within the same axiomatic system. But Gödel and his followers took no account of brain mechanisms that generate and mediate logic. In this largely theoretical paper, but backed by previous experiments and our new ones reported below, we show that in the case of so-called 'optical illusions', there exists a significant and irreconcilable difference between their visual perception and their description according to Euclidean geometry; when participants are asked to adjust, from an initial randomised state, the perceptual geometric axioms to conform to the Euclidean description, the two never match, although the degree of mismatch varies between individuals. These results provide evidence that perceptual axioms, or statements known to be perceptually true, cannot be described mathematically. Thus, the logic of the visual perceptual system is irreconcilable with the cognitive (mathematical) system and cannot be updated even when knowledge of the difference between the two is available. Hence, no one brain reality is more 'objective' than any other.

Techniques for Percutaneous Access.

Percutaneous epicardial access continues to have a growing role within cardiac electrophysiology. The classic approach has typically been with a Tuohy needle via a subxiphoid approach guided by fluoroscopic landmarks and tactile feedback. Recent developments have highlighted the role of the micropuncture needle, electroanatomic mapping, and real-time pressure sensors to reduce complications. Further, different access sites, such as the right atrial appendage, have been described and may offer a novel approach to percutaneous epicardial access. In addition, future directions of percutaneous access may involve direct visualization, near-field impedance monitoring, and real-time virtual imaging.

Slow-pathway visualization by using voltage-time relationship: A novel technique for identification and fluoroless ablation of atrioventricular nodal reentrant tachycardia.

BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) is treatable by catheter ablation. Advances in mapping-system technology permit fluoroless workflow during ablations. As national practice trends toward fluoroless approaches, easily obtained, reproducible methods of slow-pathway identification, and ablation become increasingly important. We present a novel method of slow-pathway identification and initial ablation results from this method. METHODS AND RESULTS: We examined AVNRT ablations performed at our institution over a 12-month period. In these cases, the site of the slow pathway was predicted by latest activation in the inferior triangle of Koch during sinus rhythm. Ablation was performed in this region. Proximity of the predicted site to the successful ablation location, complication rates, and patient outcomes were recorded. Junctional rhythm was seen in 40/41 ablations (98%) at the predicted site (mean, 1.3 lesions and median, 1 lesion per case). One lesion was defined as 5 mm of ablation. The initial ablation was successful in 39/41 cases (95%); in two cases, greater or equal to 2 echo beats were detected after the initial ablation, necessitating further lesion expansion. In 8/41 cases (20%), greater than one lesion was placed during initial ablation before attempted reinduction. Complications included one transient heart block and one transient PR prolongation. During follow-up (median, day 51), one patient had lower-extremity deep-vein thrombosis and pulmonary embolus, and one had a lower-extremity superficial venous thrombosis. There was one tachycardia recurrence, which prompted a redo ablation. CONCLUSIONS: Mapping-system detection of late-activation, low-amplitude voltage during sinus rhythm provides an objective, and fluoroless means of identifying the slow pathway in typical AVNRT.

Incidence, Predictors, and Significance of Ventricular Arrhythmias in Patients With Continuous-Flow Left Ventricular Assist Devices: A 15-Year Institutional Experience.

OBJECTIVES: The aim of this study was to evaluate the incidence, predictors, and associated mortality of pre-implantation, early, and late ventricular arrhythmias (VAs) in patients receiving continuous-flow left ventricular assist devices (CFLVADs). BACKGROUND: VAs are common both pre- and post-implantation of left ventricular assist devices. Limited data exist on their prognostic impact in contemporary CFLVADs. METHODS: A retrospective review was performed to identify patients who underwent CFLVAD implantation between 2000 and 2015 with 2 years of follow-up. All VAs, defined as ventricular fibrillation, ventricular tachycardia lasting >30 s, or a ventricular rhythm requiring defibrillation, were analyzed. VAs occurring within 30 days of implantation were defined as early. Recorded outcomes included death and receipt of cardiac transplant. RESULTS: A total of 517 patients were included for analysis. Early VAs were associated with a significant reduction in survival (hazard ratio: 1.83; 95% confidence interval: 1.28 to 2.61; p = 0.001) compared with patients with late or no VAs. Pre-implantation variables independently predictive of early VAs included prior cardiac surgery (odds ratio: 1.90; 95% confidence interval: 1.09 to 3.32; p = 0.023) and pre-CFLVAD ventricular tachycardia storm (odds ratio: 3.15; 95% confidence interval: 1.49 to 6.69; p = 0.003). The incidence of early VAs from 2000 to 2007 was as high as 47%, whereas the highest incidence from 2008 to 2015 was <22%. CONCLUSIONS: VAs within 30 days after CFLVAD implantation are associated with an increased risk for death. Predictors of early VAs include prior cardiac surgery and pre-CFLVAD ventricular tachycardia storm. Temporal trends have shown a decrease in VA from 2000 to 2015. Strategies to reduce arrhythmia burden shortly after CFLVAD implantation warrant further investigation.

Prescribing trends of atrial fibrillation patients who switched from warfarin to a direct oral anticoagulant.

Direct oral anticoagulant (DOAC) agents offer several lifestyle and therapeutic advantages for patients relative to warfarin in the treatment of atrial fibrillation (AF). These alternative agents are increasingly used in the treatment of AF, however the adoption practices, patient profiles, and reasons for switching to a DOAC from warfarin have not been well studied. Through the Michigan Anticoagulation Quality Improvement Initiative, abstracted data from 3873 AF patients, enrolled between 2010 and 2015, were collected on demographics and comorbid conditions, stroke and bleeding risk scores, and reasons for anticoagulant switching. Over the study period, patients who switched from warfarin to a DOAC had similar baseline characteristics, risk scores, and insurance status but differed in baseline CrCl. The most common reasons for switching were patient related ease of use concerns (37.5%) as opposed to clinical reasons (16.5% of patients). Only 13% of patients that switched to a DOAC switched back to warfarin by the end of the study period.

Imaging the urologic patient: the utility of intravenous pyelogram in the CT scan era.

PURPOSE: An opportunity exists to evaluate the quality of care in patients undergoing intravenous pyelogram (IVP) imaging and to define the role of IVP in the computed tomography scan era. METHODS: Medical records were reviewed for patient demographics, inpatient versus outpatient setting, indication for IVP, physician/specialty who ordered IVP, and the need for subsequent imaging within a 30-day period in patients who underwent IVP from October 2007 to December 2011. Chi-square test was used to compare the number of additional radiologic examinations ordered within 30 days of the initial IVP across the different specialties ordering IVPs. RESULTS: Six hundred and eighty patients underwent IVP imaging during the study period. The primary reason to order an IVP was the evaluation of urolithiasis/flank pain (50%), followed by urologic evaluation after surgery (23%). Three hundred and twenty-five patients (48%) subsequently had an additional 547 radiologic studies within 30 days of the IVP to further evaluate their condition. Of the 325 patients undergoing additional imaging studies, 36% had differing or additional diagnostic information noted that could change medical decision-making. CONCLUSIONS: Inferior imaging of the urologic patient by IVP leads to the acquisition of additional imaging studies to render a diagnosis. IVP has a limited clinical role, and thus, its use should be strictly limited to highly select cases.

Focal cryosurgical ablation of the prostate: a single institute's perspective.

BACKGROUND: With the stage migration of prostate cancer witnessed in the late 1990's and early 2000's along with the persistent morbidities associated with prostatectomy and radiation therapy, the concept of focal prostate cancer treatment remains quite attractive. Herein we evaluate the tolerability and non-oncologic outcomes of a highly select cohort of men that underwent focal cryoablation of the prostate for the treatment of localized prostate cancer. METHODS: Pre-operatively, erectile function was assessed by SHIM questionnaire while voiding symptoms were assessed by AUA symptom score. Twenty-six highly select patients (23 low-risk prostate cancer and 3 intermediate-risk prostate cancer) with documented minimal disease on saturation prostate biopsy underwent focal cryoablation of the prostate (24 hemi-ablation and 2 subtotal ablation). Subsequently, serum PSAs were obtained every 3 months for 2 years and then every 6 months thereafter. PSA failure was defined as an increase of 0.50 ng/ml over nadir. Mean follow-up was 19.1 months. Subjective assessment of erectile function and voiding was assessed post-operatively at each visit. RESULTS: Based on our PSA failure definition, 11.5% (3 patients) of the cohort experienced biochemical failure. In two of the three patients, localized disease was detected on subsequent transrectal ultrasound guided biopsy. These two patients went on to have favorable PSA nadirs after undergoing conventional definitive therapy (one patient had external beam radiation and one patient had whole gland cryoablation). Within the study cohort, 27% (7 patients) reported new post-operative erectile dysfunction requiring therapy while no patients reported new post-operative urinary incontinence or worsening of voiding symptoms. CONCLUSION: These preliminary results add to the expanding body of literature that the minimally invasive focal cryosurgical ablation of the prostate is a safe procedure with few side effects. The true extent of cancer control remains in question, but in highly select patients, favorable PSA kinetics have been demonstrated. If confirmed by further studies with long-term follow-up, this treatment approach could have a profound effect on prostate cancer management.