Enhancing Geometric Fidelity of 3-Dimensional Electroanatomic Mapping During Open Chest Epicardial Radiofrequency Catheter Ablation

Although electroanatomic mapping techniques have been previously applied to open chest epicardial ablation procedures, such efforts have often been limited by significant geometric distortions introduced by the need to use nonstandard mapping patch placements and by intrathoracic conductance changes introduced by having the pericardial space exposed. In this article, we present a case of a patient with recurrent hemodynamically unstable ventricular tachycardia who underwent a successful open chest epicardial ablation procedure with electroanatomic mapping in which geometric distortions were minimized by judicious placement of mapping patches and the use of a saline bath within the pericardial space.

Implementation and impact analysis of a transitional care pathway for patients presenting to the emergency department with cardiac-related complaints

Background

Cardiac-related complaints are leading drivers of Emergency Department (ED) utilization. Although a large proportion of cardiac patients can be discharged with appropriate outpatient follow-up, inadequate care coordination often leads to high revisit rates or unnecessary admissions. We evaluate the impact of implementing a structured transitional care pathway enrolling low-risk cardiac patients on ED discharges, 30-day revisits and admissions, and institutional revenues.

Methods

We prospectively enrolled eligible patients presenting to a single-center Emergency Department over a 12-month period. Standardized risk measures were used to identify patients suitable for early discharge with cardiology follow-up within 5 days. The primary endpoints were rates of discharge from the ED and 30-day ED revisit and admission rates, with a secondary endpoint including 30-day returns for myocardial infarction. A cost analysis of the program’s impact on institutional revenues was performed.

Results

Among patients presenting with cardiac-related complaints, rates of discharge from the ED increased from 44.4 to 56.6% (p < 0.0001). Enrollment in the transitional care pathway was associated with a reduced risk of cardiac-related ED revisits (RR 0.22, p < 0.0001), all-cause ED revisits (RR 0.30, p < 0.0001), and admission at second ED visit (RR 0.56, p = 0.0047); among enrolled patients, the 30-day rate of return with a myocardial infarction was 0.35%. No significant reductions were seen in 30-day cardiac-related and all-cause revisits in the 12-months following transitional care pathway implementation; however, there was a significant reduction in admissions at second ED visit from 45.6 to 37.7% (p = 0.0338). An early gender disparity in care delivery was identified in the first 120 days following program implementation that was subsequently eliminated through targeted intervention. There was an estimated decline in institutional revenue of $300 per enrolled patient, driven predominantly by a reduction in admissions.

Conclusions

A structured transitional care pathway identifying low-risk cardiac patients who may be safely discharged from the ED can be effective in shifting care delivery from hospital-based to lower cost ambulatory settings without adversely impacting 30-day ED revisit rates or patient outcomes.

Converting the informed consent from a perfunctory process to an evidence-based foundation for patient decision making

BACKGROUND

Standard consent forms result in highly variable communication between patients and physicians. To enhance the consent process and facilitate shared decision making, we developed a World Wide Web-based program, PREDICT (Patient Refined Expectations for Deciding Invasive Cardiac Treatments), to systematically embed patient-specific estimates of death, bleeding, and restenosis into individualized percutaneous coronary intervention informed consent documents. We then compared patients' experiences with informed consent before and after implementation of PREDICT.

METHODS AND RESULTS

Between August 2006 and May 2007, patients undergoing nonemergent cardiac catheterization who received the original consent form (n=142) were interviewed and compared with those who received the PREDICT consent form (n=193). Hierarchical modified Poisson regression models were used to adjust for clustering of patients within physicians. Compared with the original consent group, those in the PREDICT group reported higher rates of reading the consent form (72% versus 44%, relative risk [RR] 1.64, 95% confidence interval [CI] 1.24 to 2.16), increased perception of shared decision making (67% versus 45%, RR 1.48, 95% CI 0.99 to 2.22), and decreased anxiety (35% versus 55%, RR 0.70, 95% CI 0.53 to 0.91). Although there were no differences between groups in patients' ability to name complications of percutaneous coronary intervention, among patients who identified either death or bleeding as a potential complication, more patients in the PREDICT group recalled being informed of their estimated risk of that complication (death: 85% versus 62%, RR 1.37, 95% CI 1.03 to 1.82; bleeding: 92% versus 71%, RR 1.28, 95% CI 1.06 to 1.56).

CONCLUSIONS

In this preliminary, single-center experience, individualized consent forms with patient-specific risks were associated with improved participation in the consent process, reduced anxiety, and better risk recall. PREDICT is one potential strategy for improving the current practice of obtaining informed consent for percutaneous coronary intervention.

Implementing an innovative consent form: the PREDICT experience

BACKGROUND

In the setting of coronary angiography, generic consent forms permit highly variable communication between patients and physicians. Even with the existence of multiple risk models, clinicians have been unable to readily access them and thus provide patients with vague estimations regarding risks of the procedure.

METHODS

We created a web-based vehicle, PREDICT, for embedding patient-specific estimates of risk from validated multivariable models into individualized consent documents at the point-of-care. Beginning August 2006, outpatients undergoing coronary angiography at the Mid America Heart Institute received individualized consent documents generated by PREDICT. In February 2007 this approach was expanded to all patients undergoing coronary angiography within the four Kansas City hospitals of the Saint Luke's Health System. Qualitative research methods were used to identify the implementation challenges and successes with incorporating PREDICT-enhanced consent documents into routine clinical care from multiple perspectives: administration, information systems, nurses, physicians, and patients.

RESULTS

Most clinicians found usefulness in the tool (providing clarity and educational value for patients) and satisfaction with the altered processes of care, although a few cardiologists cited delayed patient flow and excessive patient questions. The responses from administration and patients were uniformly positive. The key barrier was related to informatics.

CONCLUSION

This preliminary experience suggests that successful change in clinical processes and organizational culture can be accomplished through multidisciplinary collaboration. A randomized trial of PREDICT consent, leveraging the accumulated knowledge from this first experience, is needed to further evaluate its impact on medical decision-making, patient compliance, and clinical outcomes.

Identifying heart failure patients at high risk for near-term cardiovascular events with serial health status assessments

BACKGROUND

Identification of heart failure outpatients at increased risk for clinical deterioration remains a critical challenge, with few tools currently available to assist clinicians. We tested whether serial health status assessments with the Kansas City Cardiomyopathy Questionnaire (KCCQ) can identify patients at increased risk for mortality and hospitalization.

METHODS AND RESULTS

We evaluated 1358 patients with heart failure after an acute myocardial infarction in the Eplerenone's Neurohormonal Efficacy and Survival Study, a multicenter randomized trial that included serial KCCQ assessments. Cox proportional-hazards models were used to examine whether changes in KCCQ scores during successive outpatient visits were independently associated with all-cause mortality and cardiovascular mortality or hospitalization. Change in KCCQ (deltaKCCQ) was linearly associated with all-cause mortality (hazard ratio [HR], for each 5-point decrease in deltaKCCQ, 1.11; 95% CI, 1.04 to 1.19) and the combined outcome of cardiovascular mortality or hospitalization (HR for each 5-point decrease in deltaKCCQ, 1.12; 95% CI 1.07 to 1.18). In Kaplan-Meier survival analysis, all-cause mortality among patients with deltaKCCQ of < or = -10, > -10 to < 10, and > 10 points was 26%, 16%, and 13%, respectively (P=0.008). After multivariable adjustment, the linear relationship between deltaKCCQ and both all-cause mortality and combined cardiovascular death and hospitalization persisted (HR, 1.09; 95% CI, 1.00 to 1.18; and HR, 1.11; 95% CI, 1.05 to 1.17 for each 5-point decrease in deltaKCCQ, respectively).

CONCLUSIONS

In heart failure outpatients, serial health status assessments with the KCCQ can identify high-risk patients and may prove useful in directing the frequency of follow-up and the intensity of treatment.

Prognostic value of health status in patients with heart failure after acute myocardial infarction

BACKGROUND

Disease-specific health status instruments such as the Kansas City Cardiomyopathy Questionnaire (KCCQ) can quantify symptoms, functional limitations, and quality of life in patients with heart failure. Understanding the relationship between KCCQ scores and prognosis may assist clinicians in both interpreting KCCQ scores and stratifying risk in patients.

METHODS AND RESULTS

We examined the prognostic value of the KCCQ in a prospective, international cohort of 1516 patients with heart failure after a recent acute myocardial infarction. We focused on the relationship between the KCCQ overall score (KCCQ-os), measured at the first outpatient visit (4 weeks after enrollment), and subsequent 1-year cardiovascular mortality or hospitalization (n=258, 20.3%). KCCQ-os was strongly associated with subsequent cardiovascular events in that those with a score > or =75 had an 84% 1-year event-free survival compared with 59% for those with a score <25 (P<0.001). After demographic and other clinical characteristics were controlled for in multivariable models, KCCQ-os remained strongly associated with outcome (hazard ratio, 2.02; 95% CI, 1.24 to 3.27 for KCCQ-os <25; P<0.001).

CONCLUSIONS

In outpatients with heart failure complicating an acute myocardial infarction, KCCQ-os is strongly associated with subsequent 1-year cardiovascular mortality and hospitalization. Use of the KCCQ in outpatient clinical practice can both quantify patients' health status and provide insight into their prognosis.

Interactive computer simulations of knee-replacement surgery

OBJECTIVE

Current surgical training programs in the United States are based on an apprenticeship model. This model is outdated because it does not provide conceptual scaffolding, promote collaborative learning, or offer constructive reinforcement. Our objective was to create a more useful approach by preparing students and residents for operative cases using interactive computer simulations of surgery. Total-knee-replacement surgery (TKR) is an ideal procedure to model on the computer because there is a systematic protocol for the procedure. Also, this protocol is difficult to learn by the apprenticeship model because of the multiple instruments that must be used in a specific order. We designed an interactive computer tutorial to teach medical students and residents how to perform knee-replacement surgery. We also aimed to reinforce the specific protocol of the operative procedure. Our final goal was to provide immediate, constructive feedback.

DESCRIPTION

We created a computer tutorial by generating three-dimensional wire-frame models of the surgical instruments. Next, we applied a surface to the wire-frame models using three-dimensional modeling. Finally, the three-dimensional models were animated to simulate the motions of an actual TKR. The tutorial is a step-by-step tutorial that teaches and tests the correct sequence of steps in a TKR. The student or resident must select the correct instruments in the correct order. The learner is encouraged to learn the stepwise surgical protocol through repetitive use of the computer simulation. Constructive feedback is acquired through a grading system, which rates the student's or resident's ability to perform the task in the correct order. The grading system also accounts for the time required to perform the simulated procedure. We evaluated the efficacy of this teaching technique by testing medical students who learned by the computer simulation and those who learned by reading the surgical protocol manual. Both groups then performed TKR on manufactured bone models using real instruments. Their technique was graded with the standard protocol. The students who learned on the computer simulation performed the task in a shorter time and with fewer errors than the control group. They were also more engaged in the learning process.

DISCUSSION

Surgical training programs generally lack a consistent approach to preoperative education related to surgical procedures. This interactive computer tutorial has allowed us to make a quantum leap in medical student and resident teaching in our orthopedic department because the students actually participate in the entire process. Our technique provides a linear, sequential method of skill acquisition and direct feedback, which is ideally suited for learning stepwise surgical protocols. Since our initial evaluation has shown the efficacy of this program, we have implemented this teaching tool into our orthopedic curriculum. Our plans for future work with this simulator include modeling procedures involving other anatomic areas of interest, such as the hip and shoulder.

PapD-like chaperones provide the missing information for folding of pilin proteins

A fundamental question in molecular biology is how proteins fold into domains that can serve as assembly modules for building up large macromolecular structures. The biogenesis of pili on the surface of Gram-negative bacteria requires the orchestration of a complex process that includes protein synthesis, folding via small chaperones, secretion, and assembly. The results presented here support the hypothesis that pilus subunit folding and biogenesis proceed via mechanisms termed donor strand complementation and donor strand exchange. Here we show that the steric information necessary for pilus subunit folding is not contained in one polypeptide sequence. Rather, the missing information is transiently donated by a strand of a small chaperone to allow folding. Providing the missing information for folding, via a 13-amino acid peptide extension to the C-terminal end of a pilus subunit, resulted in the production of a protein that no longer required the chaperone to fold. This mechanism of small periplasmic chaperone function described here deviates from classical hsp60 chaperone-assisted folding.

Periplasmic chaperone recognition motif of subunits mediates quaternary interactions in the pilus

The class of proteins collectively known as periplasmic immunoglobulin-like chaperones play an essential role in the assembly of a diverse set of adhesive organelles used by pathogenic strains of Gram-negative bacteria. Herein, we present a combination of genetic and structural data that sheds new light on chaperone-subunit and subunit-subunit interactions in the prototypical P pilus system, and provides new insights into how PapD controls pilus biogenesis. New crystallographic data of PapD with the C-terminal fragment of a subunit suggest a mechanism for how periplasmic chaperones mediate the extraction of pilus subunits from the inner membrane, a prerequisite step for subunit folding. In addition, the conserved N- and C-terminal regions of pilus subunits are shown to participate in the quaternary interactions of the mature pilus following their uncapping by the chaperone. By coupling the folding of subunit proteins to the capping of their nascent assembly surfaces, periplasmic chaperones are thereby able to protect pilus subunits from premature oligomerization until their delivery to the outer membrane assembly site.

The NMR chemical shift pH measurement revisited: analysis of error and modeling of a pH dependent reference

A standard differential calculus-based propagation of error treatment is applied to the traditional chemical-exchange Henderson-Hasselbalch NMR pH model in which the reference shift is pH independent. It is seen naturally from this analysis that (i) the error minimum in derived pH occurs in the region where pH and indicator pKa are equal and that (ii) the dynamic range, or difference between the limiting chemical shifts of acid and base forms of indicator species, determines the insensitivity of the technique to propagation of errors. To extend the useful pH range and utility of NMR pH determination methodology, a more general model is developed in which the internal reference species is also considered as having a pH-dependent chemical shift. Data from standard solution pH titrations are fitted to both models and parameters are estimated for the normally observed family of ionizable phosphorus metabolites (ATP, inorganic phosphate, phosphoethanolamine and phosphocholine) and the xenometabolite 2-deoxyglucose-6-phosphate with either phosphocreatine, the alpha-phosphate of ATP, or H2O taken as the 31P or 1H chemical shift internal reference species as well as with an external reference.

Tumor 31P NMR pH measurements in vivo: a comparison of inorganic phosphate and intracellular 2-deoxyglucose-6-phosphate as pHnmr indicators in murine radiation-induced fibrosarcoma-1

Uncertainty regarding the intracellular/extracellular distribution of inorganic phosphate (P(i)) in tumors has raised concerns that pH calculated from the tumor P(i) chemical shift may not accurately represent the intracellular pH (pHin). This issue was addressed in subcutaneously transplanted murine radiation induced fibrosarcoma-1 by directly comparing pH measured via P(i) with pH measured via the in situ generated intracellular xenometabolite 2-deoxyglucose-6-phosphate (2DG6P). In 131 comparative measurements employing eight tumor-bearing mice under both control and hyperglycemic conditions (the latter to extend the range of tumor pH examined), the pH as derived from either 2DG6P or P(i) showed only a small, but statistically significant, difference (0.07 +/- 0.11 SD; P = 0.0001). Scatter in the comparative analysis over the pH range examined (ca. 5.5-7.5) was not uniform. Above pH 6.6, 2DG6P indicated a pH lower than that of P(i) by 0.088 +/- 0.105 SD (n = 107, P = 0.0001); below pH 6.6, 2DG6P indicated a pH essentially identical to and not statistically different from that of P(i) (mean difference 0.003 +/- 0.128 SD (n = 24, P = 0.92)). Evidence is presented in support of this differential arising from a systematic measurement error due to peak overlap between 2DG6P and endogenous phosphomonoester species. These results support the use of P(i) as a tumor 31P NMR pHin indicator, at least in RIF-1 tumors under control and hyperglycemic conditions.

Serial section electron tomography: a method for three-dimensional reconstruction of large structures

We present a method for combining single axis tomography and serial sectioning techniques to derive a three-dimensional reconstruction of large structures at electron microscopic resolution. This serial-tomography method allows the use of sufficiently thin sections to achieve adequate resolution with electron tomography, yet enables the generation of large reconstructions with considerably fewer sections than would be required using a serial thin section reconstruction technique. Serial thick sections (1-2 microns) are cut through the structure of interest, tomographic volume reconstructions are obtained for each section from a single axis tilt series, and the resulting series of volumes are then aligned and combined to form a single large volume. The serial-tomography method is illustrated with several samples, including red blood cells, the Golgi apparatus, and a spiny dendrite of a cortical pyramidal neuron. In some of these samples, the reconstruction is compared to correlated light microscopic views. The resulting large volume reconstructions appear to represent accurately the size and shape of objects such as red blood cells and spiny dendrites. The continuity of complex, tortuous structures such as the Golgi apparatus is also maintained across serial volumes. These examples demonstrate that it is possible to align and link a series of tomographic volumes accurately and that serial-tomography is a useful method for reconstructing relatively large structures without resorting to large numbers of serial thin sections.