Resetting and Entrainment of Reentrant Arrhythmias: Part I: Concepts,Recognition, and Protocol for Evaluation: Surface ECG versus Intracardiac Recordings

In this paper, we review the information accumulated over the years regarding the phenomena of resetting and entrainment of reentrant arrhythmias. Over three decades of research and clinical applications, these phenomena have demonstrated that they stay as a main tool for an intellectual understanding of reentry and to base strategies for localization of critical areas for ablative therapies. This review will be divided into two parts. This first part deals with the bases for the concept development, the means for the detection of these phenomena, and their mechanistic implications. Resetting is described as a particular response of a given rhythm to an external perturbation, indicating interaction between them. Entrainment indicates continuous reset of the rhythm when the perturbation is repetitive. The mechanisms that explain these responses in reentrant rhythms are presented. Fusion, both at the surface electrocardiogram and at the level of intracardiac recordings, is discussed in detail, with its value and limitations as a key concept to recognize entrainment and reentry. Computer simulations are used as an aid to a better understanding. Differences between resetting and entrainment are considered, and a pacing protocol to study these phenomena described.     

Application of a Clinical Magnet over Implantable Cardioverter Defibrillators: Is It Safe and Useful?

The growing number of implantable cardioverter defibrillator (ICD) implants mean that a high number of patients carrying these devices are attended by physicians. In an attempt to simplify their management, articles have been published on the safety of applying magnets to the ICD in order to avoid the administration of shocks during surgery. However, performance of these procedures without the supervision of expert personnel can be accompanied by serious and potentially fatal complications. We report a case where the use of a clinic magnet over an ICD caused it to switch to “end of life” in the battery indicator and lose some antitachycardia therapies.     

Response to Cardiac Resynchronization Therapy: Is It Time to Expand the Criteria?

Background: Cardiac resynchronization therapy (CRT) is a promising treatment for a subgroup of patients with advanced congestive heart failure and a prolonged QRS interval. Despite the majority of patients benefiting from CRT, 10–40% of patients do not respond to this treatment and are labeled as nonresponders. Given that there is a lack of consensus on how to define response to CRT, the purpose of this viewpoint is to discuss currently used definitions and their shortcomings, and to provide recommendations as to how an expansion of the criteria for CRT response may be useful to clinicians.
Methods and Results: Analysis of the literature and case reports indicates that the majority of established measures of CRT response, including New York Heart Association functional class and echocardiographic, hemodynamic, and neurohormonal parameters, are poor associates of patient-reported symptoms and quality of life. Moreover, the potential moderating role of psychological factors in determining health outcomes after CRT has largely been neglected.
Conclusions: It is recommended to routinely assess health status after CRT with a disease-specific questionnaire in standard clinical practice and to examine its determinants, including psychological factors such as personality traits and depression. This may lead to improved (secondary) treatment and prognosis in CHF patients treated with CRT.     

Transient Pigmentary Lines of the Newborn

Letters to the Editor are welcomed for publication (subject to editing). Letters must be signed by all authors, and must not exceed two pages of text including references. Letters should not duplicate material submitted or published in other journals. Prepublication proofs will not be provided.     

Sequential Variations in the Content of Bone Marrow Colony-forming Cells in Individual Patients with Aplastic Anemia Before and After Immunosuppressive Therapy; Hematopoiesis

Previous studies have shown that the levels of hematopoietic progenitor cells (colony-forming cells; CFC) are drastically reduced in the vast majority of patients with aplastic anemia (AA). This has been observed both in patients before and after immunosuppressive therapy. In those studies, however, both groups of patients were usually formed by different individuals, thus it was not possible to follow the kinetics of such cells in each particular patient. In the present study, we have determined the content of myeloid and erythroid CFC in individual AA patients before and after therapy. Treated patients were studied at two different times (8-18 months apart) to detect any possible variations due to the ongoing treatment. At diagnosis, the levels of both myeloid and erythroid CFC were drastically reduced, as compared to normal bone marrow, in all the patients studied. This correlated with very low levels of leukocytes and hemoglobin in circulation. After the patients entered an immunosuppressive treatment, all of them showed significant increments in their CFC levels, and this correlated with increments in their hematological parameters in peripheral blood. However, in most patients CFC levels were still below the normal range. When the second sample after treatment was obtained, great variations in CFC numbers were observed. In terms of erythroid CFC levels, a further increase was seen in most patients, and this correlated with a further increase in hemoglobin levels. In contrasts, the levels of myeloid CFC were increased in only some of the patients, whereas in others, significant reductions were evident. Interestingly, in this latter group of patients, CFC never reached the levels observed before treatment. Our results indicate that, in a significant proportion of patients, a common pattern seems to exist. That is to say, low CFC numbers are present before treatment; an increase in the numbers of such cells results as an effect of the immunosuppressive therapy and further variations in CFC numbers (within individual limits that may differ significantly from one patient to another) take place as long as the treatment continues. Finally, we observed a correlation between CFC levels and the clinical status of the patients, i.e., those patients that showed a complete or a partial response to treatment showed higher levels of both myeloid and erythroid CFC than those patients that did not respond to therapy.     

The Effects of Quality of Care on Costs: A Conceptual Framework

Context

The quality of health care and the financial costs affected by receiving care represent two fundamental dimensions for judging health care performance. No existing conceptual framework appears to have described how quality influences costs.

Methods

We developed the Quality-Cost Framework, drawing from the work of Donabedian, the RAND/UCLA Appropriateness Method, reports by the Institute of Medicine, and other sources.

Findings

The Quality-Cost Framework describes how health-related quality of care (aspects of quality that influence health status) affects health care and other costs. Structure influences process, which, in turn, affects proximate and ultimate outcomes. Within structure, subdomains include general structural characteristics, circumstance-specific (e.g., disease-specific) structural characteristics, and quality-improvement systems. Process subdomains include appropriateness of care and medical errors. Proximate outcomes consist of disease progression, disease complications, and care complications. Each of the preceding subdomains influences health care costs. For example, quality improvement systems often create costs associated with monitoring and feedback. Providing appropriate care frequently requires additional physician visits and medications. Care complications may result in costly hospitalizations or procedures. Ultimate outcomes include functional status as well as length and quality of life; the economic value of these outcomes can be measured in terms of health utility or health-status-related costs. We illustrate our framework using examples related to glycemic control for type 2 diabetes mellitus or the appropriateness of care for low back pain.

Conclusions

The Quality-Cost Framework describes the mechanisms by which health-related quality of care affects health care and health status–related costs. Additional work will need to validate the framework by applying it to multiple clinical conditions. Applicability could be assessed by using the framework to classify the measures of quality and cost reported in published studies. Usefulness could be demonstrated by employing the framework to identify design flaws in published cost analyses, such as omitting the costs attributable to a relevant subdomain of quality.     

Rescue Angioplasty: Characteristics and Results in a Single‐Center Experience

Purpose and Methods: Rescue angioplasty (RA) has demonstrated its efficacy for the treatment of failed thrombolysis after acute myocardial infarction (AMI). We analyzed clinical, angiographic, and procedural characteristics, and prognosis at 30 days of prospective cohort of unselected patients admitted for RA. Results: From August 2004 to August 2009, 361 patients were included in a single center. The median time pain to the thrombolysis was 140 minutes (interquartile range [IQR] 90–210), delay transfer 100 minutes (IQR 65–120); pain to PCI was 330 minutes (IQR 270–400). Initial flow TIMI 3 (Thrombolysis in Myocardial Infarction) was presented in 102 (28.3%) of cases and blush grade 3 in 88 (24.4%). After the procedure, TIMI 3 flow was achieved in 286 (79.2%) and blush grade 3 in 256 (71%) (P < 0.001 and P < 0,001, respectively). A glycoprotein IIb/IIIa receptor inhibitor (Abciximab) was used in 115 patients (32%). Stents were implanted in 339 (94%) of patients, 137 (38%) of which were drug‐eluting stent. Complete ST segment resolution was observed in 202 (64.5%) patients in 12‐lead electrocardiogram (ECG) and procedural success was 77.6%. Adverse cardiac events and death after 30 days follow‐up were 13.6% and 10.7%, respectively. Target vessel revascularization at 30 days was 1.9%. Conclusions: Routine application of RA in patients with persistent ST elevation 90 minutes after thrombolysis is a useful technique for achieving revascularization of the affected artery. In‐hospital mortality remains high especially in patients with cardiac shock, despite new interventional techniques available, and adjunctive antithrombotic therapy. (J Interven Cardiol 2011;24:42–48)