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Robert S D Higgins

Publications and source records attributed to Robert S D Higgins.

10 recordsLinked to original sources
PubMed2006

Electrical remodeling in a canine model of ischemic cardiomyopathy.

The nature of electrical remodeling in a canine model of ischemic cardiomyopathy (ICM; induced by repetitive intracoronary microembolizations) that exhibits spontaneous ventricular tachycardia is not entirely clear. We used the patch-clamp technique to record action potentials and ionic currents of left ventricular myocytes isolated from the region affected by microembolizations. We also used the immunoblot technique to examine channel subunit expression in adjacent affected tissue. Ventricular myocytes and tissue isolated from the corresponding region of normal hearts served as control. ICM myocytes had prolonged action potential duration (APD) and more pronounced APD dispersion. Slow delayed rectifier current (I(Ks)) was reduced at voltages positive to 0 mV, along with a negative shift in its voltage dependence of activation. Immunoblots showed that there was no change in KCNQ1.1 (I(Ks) pore-forming or alpha-subunit), but KCNE1 (I(Ks) auxiliary or beta-subunit) was reduced, and KCNQ1.2 (a truncated KCNQ1 splice variant with a dominant-negative effect on I(Ks)) was increased. Transient outward current (I(to)) was reduced, along with an acceleration of the slow phase of recovery from inactivation. Immunoblots showed that there was no change in Kv4.3 (alpha-subunit of fast-recovering I(to) component), but KChIP2 (beta-subunit of fast-recovering component) and Kv1.4 (alpha-subunit of slow-recovering component) were reduced. Inward rectifier current was reduced. L-type Ca current was unaltered. The immunoblot data provide mechanistic insights into the observed changes in current amplitude and gating kinetics of I(Ks) and I(to). We suggest that these changes, along with the decrease in inward rectifier current, contribute to APD prolongation in ICM hearts.

Action Potentials↗
PubMed2006

Risk stratification of in-hospital mortality for coronary artery bypass graft surgery.

OBJECTIVES: The purpose of this research was to develop a risk index for in-hospital mortality for coronary artery bypass graft (CABG) surgery. BACKGROUND: Risk indexes for CABG surgery are used to assess patients' operative risk as well as to profile hospitals and surgeons. None has been developed using data from a population-based region in the U.S. for many years. METHODS: Data from New York's Cardiac Surgery Reporting System in 2002 were used to develop a statistical model that predicts mortality and to create a risk index based on a relatively small number of patient risk factors. The fit of the index was tested by applying it to another year (2003) of New York data and testing the correspondence of expected and observed mortality rates for each risk score in the index. RESULTS: The risk index contains a total of 10 risk factors (age, female gender, hemodynamic state, ejection fraction, pre-procedural myocardial infarction, chronic obstructive pulmonary disease, calcified ascending aorta, peripheral arterial disease, renal failure, and previous open heart operations). The score possible for each variable ranges from 0 to 5, and total risk scores possible range from 0 to 34. The highest score observed for any patient was 22, and 93% of the patients had scores of 8 or lower. When the risk index was applied to another year of New York data with a considerably lower mortality rate, the C-statistic was 0.782. CONCLUSIONS: The risk index appears to be a valuable tool for predicting patient risk when applied to another year of New York data. It should now be tested against other risk indexes in a variety of geographical regions.

Aged↗
PubMed2005

Long-term results of surgical coarctectomy in the adolescent and young adult with 18-year follow-up.

BACKGROUND: There is no consensus in the literature regarding the optimal method for repair of coarctation of the aorta in the adolescent and young adult. METHODS: We retrospectively reviewed operations in 45 patients treated between 1978 and 2003. RESULTS: From 1978 to 2001, there were 45 adolescents or adults between the ages of 11 and 53 years (mean 21, SD +/- 10) who underwent surgical correction. The perioperative mortality rate was 0% and the morbidity rate was 18%. All patients had improved blood pressure before discharge after a mean of 7 days, which ranged from 160/90 mm Hg to 90/50 mm Hg (mean 128/73 mm Hg, SD +/- 17/12 mm Hg). This was an average improvement of 35 mm Hg (SD +/- 26) compared with the preoperative pressure (p < 0.0005). Long-term results (defined as 5 years or more) were documented for 30 (71%) with a mean follow-up of 18.2 years (range, 67 to 293 months; SD +/- 70 months). At the time of last follow-up, the blood pressure was documented and averaged 122/73 mm Hg (SD +/- 11/10 mm Hg), which was a decrease of 36 mm Hg (SD +/- 29) compared with the preoperative pressure (p < 0.0005). Seventy-six percent of patients were on no medications for hypertension. None of the 30 patients available for long-term follow-up has required a second operation for recurrence. CONCLUSIONS: Surgical repair of coarctation in the adolescent and adult is safe and durable, with a high success rate in curing patients of hypertension and making them medication-free for life. The recurrence rate is low, and most patients will not require any further intervention.

Adolescent↗
PubMed2004

Implementing the ACGME general competencies in a cardiothoracic surgery residency program using 360-degree feedback.

BACKGROUND: Methods to assess the six competency categories outlined by the Accreditation Council on Graduate Medical Education are essential to allow residency programs to develop reproducible evaluations of their educational curriculum. Current tools to evaluate competencies are insufficient to perform these tasks, particularly in subspecialty disciplines. The key objective of this initiative was to develop and implement an evaluative tool that would provide data to residents and program leadership regarding their performance and to provide the training program with a reliable way to assess this component of the program. METHODS: Utilizing a highly customized survey tool with a group of cardiothoracic residents, we implemented a 360-degree performance assessment process based on the six Accreditation Council on Graduate Medical Education competency areas. The full spectrum of associations in a resident's sphere of interaction were surveyed (ie, supervisors, peers, direct reports, nurses, and administrative personnel). Each resident received a comprehensive report that included detailed documentation of the self-evaluation and the average rating of others by category. Each resident also received a transcript of the responses to the open-ended questions and summary of the data highlighting areas of excellence, areas for improvement, and suggested goals and recommendations. The program director received copies of all of these as well as a chart documenting the average scores on each item for the whole cohort. RESULTS: Each resident met with the 360-degree feedback specialist and the program director to develop and commit to an action plan based on the feedback. The feedback process was repeated approximately 8 months later. CONCLUSIONS: The 360-degree feedback results provided valuable information for the residents. It also provided our program with a reproducible, quantifiable tool to assess these competencies. Combined with other instruments, the 360-degree feedback was found to be a particularly valuable instrument.

Accreditation↗
PubMed2004

Plasmolemmal potassium gradient does not affect lung protection by an ATP-regulated potassium channel opener.

BACKGROUND: We have previously shown that metabolic arrest induced with ATP-regulated potassium channel openers (PCOs) can improve lung preservation by adding Aprikalim (a PCO, Rhone-Poulene Roher) to modified Euro-Collins solution for pulmonary artery flush. Because the membrane hyperpolarizing effects of a PCO potentially competes with the depolarizing effects of a hyperkalemic solution, this study evaluated the effects of the potassium gradient on PCO-mediated lung protection. STUDY DESIGN: Twenty rabbits underwent lung protection in four groups. Group 1 underwent harvest and reperfusion as a "no ischemia" control. Groups 2, 3, and 4 underwent harvest followed by 18 hours of cold ischemic storage before reperfusion. Groups 1 and 4 received Euro Collins as the pulmonary flush at induction of ischemia. Group 2 received Euro Collins plus Aprikalim (100 microM); and group 3 received lactated Ringer's plus Aprikalim. After ischemic storage, the lungs were reperfused with autologous blood for 2 hours. Every 30 minutes, the lungs were given a 10-minute 100% fractional inspired oxygen (F(i)O(2)) challenge to measure maximal gas exchange as an indication of graft function. RESULTS: Repeated measures ANOVA showed Aprikalim improved graft function after 18 hours of cold ischemia (p < 0.0001). No significant differences were found when Aprikalim was used in either Euro-Collins (group 2) or lactated Ringer's (group 3) solution. CONCLUSIONS: The ability of the PCO Aprikalim to preserve gas exchange in a model of hypothermic pulmonary ischemia-reperfusion injury was not affected by the plasmolemmal potassium gradient. This is consistent with recent findings in myocardial protection studies that the protective effects of PCOs may be intracellular.

Adenosine Triphosphate↗
PubMed2003

Mitral valve replacement versus repair in 2003: where do we stand?

Mitral valve repair as a proportion of all mitral valve procedures continues to become more prominent in this country. As the procedures are performed more frequently and concomitantly surgeons become more comfortable performing these repairs, risks and benefits (compared with mitral valve replacement) have become better defined. The patient population and valve morphology that are most favorable for the repair approach have also been better defined, and new techniques (including minimally invasive approaches) have been reported. A prominent question remains: what to do about ischemic mitral regurgitation.

Heart Valve Prosthesis Implantation↗