Rate of Coronary Flow Adaptation in Response to Changes in Heart Rate before and during Anesthesia for Coronary Artery Surgery

Background: The rate of adaptation of coronary blood flow in response to stepwise changes in heart rate (HR) has been extensively studied in dogs and goats to improve our understanding of the dynamics of coronary regulation processes and their pathophysiology and to obtain time constants for mathematical modeling of the coronary regulation. However, little is known about the dynamic characteristics of coronary flow adaptation in humans. In patients undergoing coronary artery surgery, we investigated the rate of coronary adaptation in response to stepwise changes in HR, in the awake and anesthetized states.

Methods: In 11 patients with stable coronary artery disease, arterial blood pressure, right atrial pressure, and coronary sinus blood flow, measured by continuous thermodilution, were calculated per beat. The ratio of beat-averaged arterial blood pressure minus right atrial pressure and coronary sinus blood flow was calculated to obtain an index of coronary resistance. The rate of change of coronary resistance index was quantified by t50, defined as the time required to establish 50% of the total change in coronary resistance index. Responses of coronary resistance index after HR changes, before and after induction of anesthesia, were compared. The anesthesia technique consisted of 100 micro gram *symbol* kg sup -1 fentanyl and 0.1 mg *symbol* kg sup -1 pancuronium bromide in combination with oxygen in air ventilation (FIO2 = 0.5).

Results: In the awake situation, t50 values of the dilating and constricting responses, induced by an increase and a decrease in HR were 5.0+/-2.1 (SD) s (range 2.6-9.0 s) and 5.7+/-1.2 s (range 4.1-7.8 s), respectively. During fentanyl/pancuronium anesthesia, the rate of coronary flow adaptation was significantly slower, with t50 values of 10.2+/-2.1 s (range 7.7-13.1 s) after an HR step-up and 9.8+/-2.1 s (range 6.6-13.2 s) after an HR step-down. Compared to the awake situation, arterial blood pressure was significantly reduced during anesthesia, but coronary vascular resistance remained unchanged. This implies that the steady-state static regulation of coronary blood flow had not changed.     

Treatment synergy of silicon carbide-coated stenting and abciximab for complex coronary artery lesions: clinical results of a single-center study.

BACKGROUND: The aim of this study was to evaluate the combination of a silicon carbide-coated stent with the periprocedural use of abciximab in patients with type B2/C lesions. The study was a prospective cohort study and was conducted at the University Medical Center of Groningen. METHODS: Elective percutaneous transluminal coronary angioplasty was performed in a total of 44 patients. All had lesions with type B2/C characteristics and most were relatively small, tortuous and calcified. The involved vessel segment was stented. Silicon carbide-coated stents were used in combination with periprocedural abciximab. The main outcome measures were cardiac death, target vessel revascularization, myocardial infarction, and cerebrovascular accident. RESULTS: At 6 months of follow-up, only 4 patients had a major adverse cardiac event. Three patients had undergone target vessel revascularization and 1 patient had suffered from a cerebrovascular accident. Sixteen patients underwent re-angiography 6 months after the initial procedure. The average stenosis at 6 months was 15% with a minimal lumen diameter of 2.4 mm. CONCLUSIONS: A 9% major adverse cardiac event rate and a 7% target vessel revascularization rate at 6 months in type B2/C lesions were recorded. Further investigation on the use of this specific treatment combination is warranted.     

Diastolic dysfunction is associated with altered myocardial metabolism in asymptomatic normotensive patients with well-controlled type 2 diabetes mellitus

OBJECTIVES: This study evaluated myocardial function in relation to high-energy phosphate (HEP) metabolism in asymptomatic patients with uncomplicated type 2 diabetes mellitus using magnetic resonance (MR) techniques. BACKGROUND: Myocardial dysfunction may occur in patients with type 2 diabetes mellitus in the absence of coronary artery disease or left ventricular (LV) hypertrophy. The mechanisms underlying this diabetic cardiomyopathy are largely unknown, but may involve altered myocardial energy metabolism. METHODS: We assessed myocardial systolic and diastolic function and HEP metabolism in 12 asymptomatic normotensive male patients with recently diagnosed, well-controlled type 2 diabetes and 12 controls, using MR imaging and phosphorus-31-nuclear MR spectroscopy (31P-MRS) on a 1.5 T clinical scanner; 31P-MR spectra were quantified, and myocardial HEP metabolism was expressed as phosphocreatine to adenosine-triphosphate (PCr/ATP) ratio. RESULTS: No differences were found in LV mass and systolic function between patients and controls. However, early (E) acceleration peak, deceleration peak, peak filling rate, and transmitral early-to-late diastolic peak flow (E/A) ratio, all indexes of diastolic function, were significantly decreased in patients compared with controls (p < 0.02). In addition, myocardial PCr/ATP in patients was significantly lower than in controls (1.47 vs. 1.88, p < 0.01). Inverse associations were found between myocardial PCr/ATP and E acceleration peak, E deceleration peak, and E peak filling rate (all, p < 0.05). CONCLUSIONS: These results indicate that altered myocardial energy metabolism may contribute to LV diastolic functional changes in patients with recently diagnosed, well-controlled and uncomplicated type 2 diabetes.     

Large-scale urban disaster drill involving an explosion: lessons learned by an academic medical center.

Disaster drills are an effective way to test a hospital's preparedness for real-life disasters, but an extensive amount of coordination and time is necessary to host a successful drill with a large number of victims. The lessons learned in this drill include a number of planning, education, orientation, and follow-up issues. It is not realistic to believe that a drill can be perfectly planned and practiced; therefore each drill provides another opportunity to improve on past experience.     

Shedding light on an unknown reality in solid organ transplant patients’ self‐management: A contextual inquiry study

Traditional quantitative and qualitative research methods inadequately capture the complexity of patients’ daily self‐management. Contextual inquiry methodology, using home visits, allows a more in‐depth understanding of how patients integrate immunosuppressive medication intake, physical activity, and healthy eating in their daily lives, and which difficulties they experience when doing so. This mixed‐method study comprised 2 home visits in 19 purposively selected adult heart, lung, liver, and kidney transplant patients, asking them to demonstrate how they implement the aforementioned health behaviors. Meanwhile, conversations were audio‐taped and photographs were taken. Audio‐visual materials were coded using directed content analysis. Difficulties and supportive strategies were identified via inductive thematic analysis. We learned that few patients understood what “sufficiently active” means. Physical discomforts and poor motivation created variation across activity levels observed. Health benefits of dietary guidelines were insufficiently understood, and their implementation into everyday life considered difficult. Many underestimated the strictness of immunosuppressive medication intake, and instructions on handling late doses were unclear. Interruptions in routine and busyness contributed to nonadherence. We also learned that professionals often recommend supportive strategies, which patients not always like or need. This contextual inquiry study revealed unique insights, providing a basis for patient‐tailored self‐management interventions.