Pressure-Volume Loops for Reviewing Right Ventricular Physiology and Failure in the Context of Left Ventricular Assist Device Implantation

Right ventricular (RV) function is complex as a number of determinants beyond preload, inotropy and afterload play a fundamental role. In particular, arterial elastance (Ea), ventriculo-arterial coupling (VAC), and (systolic) ventricular interdependence play a vital role for the right ventricle. Understanding and actively visualizing these interactions in the failing RV as well as in the altered hemodynamic and morphological situation of left ventricular assist device (LVAD) implantation may aid clinicians in their understanding of RV dysfunction and failure. While, admittedly, hard data is scarce and invasive pressure-volume loop measurements will not become routine in cardiac surgery, we hope that clinicians will benefit from the comprehensive, simulation-based review of RV pathology. In particular, the aim of this article is to first, address and clarify the pathophysiologic hemodynamic factors that lead to RV dysfunction and then, second, expand upon this basis examining the changes occurring by LVAD implantation. This is illustrated using Harvi software which shows elastance, ventricular arterial coupling, and ventricular interdependence by simultaneously showing pressure volume loops of the right and left ventricle.

Protamine titration to optimize heparin antagonization after cardiopulmonary bypass

OBJECTIVES

To optimize protamine titration for heparin antagonization after weaning from cardiopulmonary bypass (CPB).

DESIGN

A prospective, observational trial.

SETTING

Single-center, non-university teaching hospital.

PARTICIPANTS

Forty patients presenting for elective on-pump coronary artery bypass grafting with or without single valve surgery.

INTERVENTIONS

At the end of CPB, the residual amount of heparin in the patient was estimated using a Bull-curve. The total protamine dose was calculated as 1 unit of protamine for 1 unit of heparin. Protamine was administered as 5 aliquots containing 20% of the total protamine dose each, with 2-min intervals.

MEASUREMENTS AND MAIN RESULTS

Activated Clotting Time (ACT) values were measured 2 min after administration of each aliquot. ROTEM(®)-analysis was performed after the full dose of protamine had been administered. After 60% of the total protamine dose had been administered, ACT values were normalized in 86.5% of patients. After the complete dose of protamine had been administered, 61.1% of patients displayed signs of protamine overdose on ROTEM(®)-analysis.

CONCLUSIONS

In patients who present for on-pump coronary artery bypass grafting with or without single valve surgery, a 0.6-to-1 ratio of protamine-to-heparin to antagonize heparin may be sufficient and beneficial for patients.

A method to convert neural signals into sound sequences

We present a method to convert neural signals into sound sequences, with the constraint that the sound sequences precisely reflect the sequences of events in the neural signal. The method consists in quantifying the wave motifs in the signal and using these parameters to generate sound envelopes. We illustrate the procedure for sleep delta waves in the human electro-encephalogram (EEG), which are converted into sound sequences that encode the time structure of the original EEG waves. This procedure can be applied to synthesize personalized sound sequences specific to the EEG of a given subject.

Pituitary surgery as alternative to dopamine agonists treatment for microprolactinomas: a cohort study

OBJECTIVE

Microprolactinomas are currently treated with dopamine agonists. Outcome information on microprolactinoma patients treated by surgery is limited. This study reports the first large series of consecutive non-invasive microprolactinoma patients treated by pituitary surgery and evaluates the efficiency and safety of this treatment.

DESIGN

Follow-up of a cohort of consecutive patients treated by surgery.

METHODS

Between January 2008 and October 2020, 114 adult patients with pure microprolactinomas were operated on in a single tertiary expert neurosurgical department, using an endoscopic endonasal transsphenoidal approach. Eligible patients presented with a microprolactinoma with no obvious cavernous invasion on MRI. Prolactin was assayed before and after surgery. Disease-free survival was modeled using Kaplan-Meier representation. A cox regression model was used to predict remission.

RESULTS

Median follow-up was 18.2 months (range: 2.8-155). In this cohort, 14/114 (12%) patients were not cured by surgery, including ten early surgical failures and four late relapses occurring 37.4 months (33-41.8) after surgery. From Kaplan-Meier estimates, 1-year and 5-year disease free survival was 90.9% (95% CI: 85.6-96.4%) and 81% (95% CI: 71.2-92.1%) respectively. The preoperative prolactinemia was the only significant preoperative predictive factor for remission (P < 0.05). No severe complication was reported, with no anterior pituitary deficiency after surgery, one diabetes insipidus, and one postoperative cerebrospinal fluid leakage properly treated by muscle plasty.

CONCLUSIONS

In well-selected microprolactinoma patients, pituitary surgery performed by an expert neurosurgical team is a valid first-line alternative treatment to dopamine agonists.

Anesthetic neurotoxicity in the pediatric population: a systematic review of the clinical evidence

Background: Exposure to general anesthesia (GA) in early life is known to be neurotoxic to animals. Objectives: To evaluate the risk of GA inducing long-term neurodevelopmental deficits in human children. Design: Systematic review. Methods: We included observational and randomized studies that compared the long-term neurodevelopment of postnatal children exposed to GA to the long-term neurodevelopment of children not exposed to GA. We searched MEDLINE, Embase and Web of Science for relevant studies published in the year 2000 or later. We screened all the identified studies on predetermined inclusion and exclusion criteria. A risk of bias assessment was made for each included study. We identified 9 neurodevelopmental domains for which a sub-analysis was made: intelligence; memory; learning; language/speech; motor function; visuospatial skills; development/emotions/behavior; ADHD/attention; autistic disorder. Results: We included 26 studies involving 605.391 participants. Based on AHRQ-standards 11 studies were of poor quality, 7 studies were of fair quality and 8 studies were of good quality. The major causes of potential bias were selection and comparability bias. On 2 neurodevelopmental domains (visuospatial skills and autistic disorder), the available evidence showed no association with exposure to GA. On 7 other neurodevelopmental domains, the available evidence showed mixed results. The 4 studies that used a randomized or sibling-controlled design showed no association between GA and neurodevelopmental deficits in their primary endpoints. Limitations: The absence of a meta-analysis and funnel plot. Conclusions: Based on observational studies, we found an association between GA in childhood and neuro-developmental deficits in later life. Randomized and sibling-matched observational studies failed to show the same association and therefore no evidence of a causal relationship exists at present. Since GA seems to be a marker, but not a cause of worse neurodevelopment, we argue against delaying or avoiding interventional or diagnostic procedures requiring GA in childhood based on the argument of GA-induced neurotoxicity.

High-sensitivity cardiac troponin release after conventional and minimally invasive cardiac surgery

After cardiac surgery, a certain degree of myocardial injury is common. The arbitrarily proposed biomarker cut-off point in the Third Universal Definition for diagnosing coronary artery bypass grafting (CABG)–related perioperative myocardial infarction (PMI) is controversial and unvalidated for non-CABG surgery. Minimally invasive cardiac surgery is often thought to be associated with less myocardial damage compared to conventional surgical approaches. We conducted a real-life prospective study with serial sampling of high-sensitivity cardiac troponin T (hs-cTnT) in patients undergoing conventional and minimally invasive cardiac surgery. Four different types of cardiac surgery were performed in 400 patients (February 2014–January 2015): CABG, aortic valve replacement, minimally invasive mitral/tricuspid valve surgery through the HeartPort (HP) technique and combined CABG/valve surgery. Each group was further subdivided for comparison between the different surgical techniques. Blood samples were collected consecutively at intensive care unit (ICU) admission and 3, 6, 9, 12, 18, 24 and 48 h thereafter. The hs-cTnT values by peak timepoint differed significantly depending on the surgical approach. The overall peak timepoint for hs-cTnT occurred 6 h after ICU admission. The combined surgery and multiple-valve HP groups had the highest values (medians of 1067.5 (744.9–1455) ng/L and 1166 (743.7–2470) ng/L, respectively). The peak hs-cTnT values for patients developing PMI showed high variability. Differentiation between cardiac surgery–related necrosis and PMI remains challenging. This study emphasizes the importance of a clinically reliable biomarker cut-off value in addition to electrocardiography and echocardiography to optimize PMI diagnosis.

Glucose Control in the ICU: A Continuing Story

In the present era of near-continuous glucose monitoring (CGM) and automated therapeutic closed-loop systems, measures of accuracy and of quality of glucose control need to be standardized for licensing authorities and to enable comparisons across studies and devices. Adequately powered, good quality, randomized, controlled studies are needed to assess the impact of different CGM devices on the quality of glucose control, workload, and costs. The additional effects of continuing glucose control on the general floor after the ICU stay also need to be investigated. Current algorithms need to be adapted and validated for CGM, including effects on glucose variability and workload. Improved collaboration within the industry needs to be encouraged because no single company produces all the necessary components for an automated closed-loop system. Combining glucose measurement with measurement of other variables in 1 sensor may help make this approach more financially viable.

Spatially Structured Sparse Morphological Component Separation for voltage-sensitive dye optical imaging

BACKGROUND

Voltage-sensitive dye optical imaging is a promising technique for studying in vivo neural assemblies dynamics where functional clustering can be visualized in the imaging plane. Its practical potential is however limited by many artifacts.

NEW METHOD

We present a novel method, that we call "SMCS" (Spatially Structured Sparse Morphological Component Separation), to separate the relevant biological signal from noise and artifacts. It extends Generalized Linear Models (GLM) by using a set of convex non-smooth regularization priors adapted to the morphology of the sources and artifacts to capture.

RESULTS

We make use of first order proximal splitting algorithms to solve the corresponding large scale optimization problem. We also propose an automatic parameters selection procedure based on statistical risk estimation methods.

COMPARISON WITH EXISTING METHODS

We compare this method with blank subtraction and GLM methods on both synthetic and real data. It shows encouraging perspectives for the observation of complex cortical dynamics.

CONCLUSIONS

This work shows how recent advances in source separation can be integrated into a biophysical model of VSDOI. Going beyond GLM methods is important to capture transient cortical events such as propagating waves.

Silent, but not unseen: multimicrocystic aspect on T2-weighted MRI in silent corticotroph adenomas

OBJECTIVE

Silent corticotroph adenomas (SCAs) present as nonfunctional pituitary tumours in routine pre-operative evaluation. The objective of this study was to evaluate the diagnostic accuracy of MRI T2-weighted sequences for detecting the corticotroph subtype pre-operatively.

DESIGN

The pre-operative T2-weighted MRI sequences were retrospectively evaluated in patients with SCA and two control groups: clinically manifest corticotroph macroadenomas (CSMs) and nonfunctional gonadotroph macroadenomas (NFGMs). All were selected from a registry of 1096 patients in whom transsphenoidal surgery was performed in the same tertiary reference centre. T2-weighted MRI sequences were independently classified by one senior endocrinologist and one senior radiologist who were blinded to the clinical and histological features.

PATIENTS

Seventeen patients with SCA, 14 with CSM and 60 with NFGM were included in this study.

MEASUREMENTS

Pituitary MRI with T2-weighted sequences. Two aspects were retained: multiple microcysts (MMs) and the absence of microcysts. Hormonal data included plasma prolactin, IGF-1, testosterone or oestradiol, LH, FT4, TSH, morning plasma cortisol and an ACTH-stimulation test, when available.

RESULTS

Multiple microcysts were present in 76% (13/17) of SCAs, 21% (3/14) of CSMs and 5% (3/60) of NFGMs. The presence of MMs in clinically nonfunctioning macroadenomas had a sensitivity of 76% and a specificity of 95% for predicting SCA.

CONCLUSION

The presence of MMs in T2-weighted MRI is a good diagnostic tool to suggest the corticotroph subtype in an apparently nonfunctional pituitary tumour.

Continuous glucose control in the ICU: report of a 2013 round table meeting

Achieving adequate glucose control in critically ill patients is a complex but important part of optimal patient management. Until relatively recently, intermittent measurements of blood glucose have been the only means of monitoring blood glucose levels. With growing interest in the possible beneficial effects of continuous over intermittent monitoring and the development of several continuous glucose monitoring (CGM) systems, a round table conference was convened to discuss and, where possible, reach consensus on the various aspects related to glucose monitoring and management using these systems. In this report, we discuss the advantages and limitations of the different types of devices available, the potential advantages of continuous over intermittent testing, the relative importance of trend and point accuracy, the standards necessary for reporting results in clinical trials and for recognition by official bodies, and the changes that may be needed in current glucose management protocols as a result of a move towards increased use of CGM. We close with a list of the research priorities in this field, which will be necessary if CGM is to become a routine part of daily practice in the management of critically ill patients.

Patients lost to follow-up in acromegaly: results of the ACROSPECT study

OBJECTIVE

The complex management of acromegaly has transformed this disease into a chronic condition, with the risk of patients being lost to follow-up. The objective of this study was to estimate the proportion of acromegalic patients lost to follow-up in France and to determine the impact that abandoning follow-up has on the disease and its management.

DESIGN

ACROSPECT was a French national, multicentre, cross-sectional, observational study.

METHODS

Acromegalic patients were considered lost to follow-up if no new information had been entered in their hospital records during the previous 2 years. They were traced where possible, and data were collected by means of a recall visit or questionnaire.

RESULTS

In the study population, 21% of the 2392 acromegalic patients initially followed in 25 tertiary endocrinology centres were lost to follow-up. At their last follow-up visit, 30% were uncontrolled, 33% were receiving medical therapy and 53% had residual tumour. Of the 362 traced, 62 had died and 77% were receiving follow-up elsewhere; the leading reason for abandoning follow-up was that they had not been informed that it was necessary. Our analysis of the questionnaires suggests that they were not receiving optimal follow-up.

CONCLUSIONS

This study underlines the need to better inform acromegalic patients of the need for long-term follow-up, the absence of which could be detrimental to patients' health, and to develop shared care for what must now be regarded as a chronic disease.

Cerebral haemodynamic physiology during steep Trendelenburg position and CO(2) pneumoperitoneum

BACKGROUND

The steep (40°) Trendelenburg position optimizes surgical exposure during robotic prostatectomy. The goal of the current study was to elucidate the influence of this patient positioning on cerebral blood flow and zero flow pressure (ZFP), and to assess the validity of different methods of evaluating ZFP.

METHODS

In 21 consecutive patients who underwent robotic endoscopic radical prostatectomy under general anaesthesia, transcranial Doppler flow velocity waveforms and invasive arterial and central venous pressure (CVP) waveforms suitable for analysis were recorded throughout the whole operative procedure in 14. The ZFP was determined by regression analysis of the pressure-flow plot and by different simplified formulas. The effective cerebral perfusion pressure (eCPP), pulsatility index (PI), and resistance index (RI) were determined.

RESULTS

While patients were in the Trendelenburg position, the ZFP increased in parallel with the CVP. The PI, RI, gradient between the ZFP and CVP, and the gradient between the CPP and the eCPP did not increase significantly (P<0.05) after 3 h of the steep Trendelenburg position. Using the formula described by Czosnyka and colleagues, the ZFP correlated closely with that calculated by linear regression throughout the course of the operation.

CONCLUSIONS

Prolonged steep Trendelenburg positioning and CO(2) pneumoperitoneum does not compromise cerebral perfusion. ZFP and eCPP are reliable variables for assessing brain perfusion during prolonged steep Trendelenburg positioning.

Management of tight intraoperative glycemic control during off-pump coronary artery bypass surgery in diabetic and nondiabetic patients

OBJECTIVES

To optimize intra- and postoperative insulin management in cardiac surgical patients.

DESIGN

A prospective, randomized, open-label, single-center study.

SETTING

A large nonuniversity hospital.

PARTICIPANTS

Sixty diabetics and 60 nondiabetics undergoing off-pump cardiac bypass surgery.

INTERVENTIONS

Intra- and postoperative tight glycemic control were achieved using different approaches with a modified insulin protocol.

MEASUREMENTS AND MAIN RESULTS

Nondiabetics were divided randomly: in the ND-ind group (n = 30), insulin was started at induction according to preinduction blood glucose (BG) concentrations. In group ND >110 (n = 30), insulin was started when BG concentrations exceeded 110 mg/dL during surgery. Up to 85% of the ND >110 group started on insulin intraoperatively. Intraoperatively, the ND-ind group had more BG within target (80-110 mg/dL) (p = 0.002), less BG >130 mg/dL (p = 0.015), and more BG between 70 and 79 mg/dL (p = 0.002). In diabetics, BG concentration was checked every 30 (DM-30), n = 30) versus 60 minutes (DM-60, n = 30) to improve the protocol's performance. Intraoperatively, there were more BG concentrations within target (80-110 mg/dL) (p = 0.02) and less >130 mg/dL (p = 0.0002) in the DM-30 group. During surgery, the hyperglycemic index and the glycemic penalty index were lower in the ND-ind group (p < 0.05). Postoperatively, the mean BG concentrations, hyperglycemic index, and glycemic penalty index in diabetics and nondiabetics were comparable between groups (p < 0.05). In the overall 2,641 BG samples, the lowest BG concentration in the operating room was 71 and in the intensive care unit (ICU) it was 61 mg/dL.

CONCLUSIONS

In diabetics and nondiabetics undergoing off-pump coronary artery bypass surgery, tight perioperative glycemic control is feasible and efficient, with minimal risks for hypo- and hyperglycemia. In nondiabetics, starting insulin therapy from induction onwards results in more measurements within target, without affecting the mean BG. In diabetics, decreasing the sampling interval from 60 to 30 minutes results in more measurements within target and in a mean blood glucose within target at ICU arrival.

Repeat dosing of rocuronium 1.2 mg kg-1 after reversal of neuromuscular block by sugammadex 4.0 mg kg-1 in anaesthetized healthy volunteers: a modelling-based pilot study

BACKGROUND

Re-intubation and re-operation may occasionally be required after neuromuscular block (NMB) reversal. This study evaluated block onset times of a second dose of rocuronium (1.2 mg kg(-1)) after sugammadex reversal of rocuronium 0.6 mg kg(-1).

METHODS

In this open-label study of healthy anaesthetized volunteers, subjects received rocuronium 0.6 mg kg(-1), were antagonized at 1-2 post-tetanic counts with sugammadex 4.0 mg kg(-1), and received rocuronium 1.2 mg kg(-1) at 5, 7.5, 10, 15, 20, 22.5, 25, 27.5, 30, 45, or 60 min after sugammadex. Spontaneous recovery occurred after repeat rocuronium dose. Primary endpoints were the onset time of maximal block (time to lowest T(1) value reached) and the clinical duration of block (until T(1)=25%) after repeat rocuronium dose.

RESULTS

Sixteen subjects were included. For subjects receiving rocuronium 1.2 mg kg(-1) 5 min after sugammadex (n=6), mean (sd) onset time (to T(1)=0) was 3.06 (0.97) min; range, 1.92-4.72 min. For repeat dose time points ≥25 min (n=5), mean onset was faster (1.73 min) than for repeat doses <25 min (3.09 min) after sugammadex. The duration of block ranged from 17.7 min (rocuronium 5 min after sugammadex) to 46 min (repeat dose at 45 min). Mean duration was 24.8 min for repeat dosing <25 min vs 38.2 min for repeat doses ≥25 min.

CONCLUSIONS

Rapid re-onset of NMB occurred after repeat dose of rocuronium 1.2 mg kg(-1) as early as 5 min after sugammadex in healthy volunteers. Re-onset of block took longer if second rocuronium dose was <25 min after sugammadex. The duration of action of second rocuronium dose increased with later repeat dose time points.

Tight glycaemic control: clinical implementation of protocols

Implementation of tight glycaemic control in hospitalised patients presents a huge challenge. It concerns many patients, there are many interfering factors and many health-care professionals are involved. The current literature provides little practical guidance. This article offers the clinical anesthesiologist direction for the organisation of inpatient blood glucose control in acute situations, in the perioperative setting and in the intensive care unit. An effective, safe and user-friendly algorithm for intravenous insulin administration is presented that can be executed by regular nurses and used in many situations. Practical advice is offered for the use of subcutaneous basal-bolus insulin, for fasting orders and for transition to discharge care. The main safety considerations are discussed.

Influence of steep Trendelenburg position and CO(2) pneumoperitoneum on cardiovascular, cerebrovascular, and respiratory homeostasis during robotic prostatectomy

BACKGROUND

The steep (40 degrees ) Trendelenburg position optimizes surgical exposure during robotic prostatectomy. The goal of the current study was to investigate the combined effect of this position and CO(2) pneumoperitoneum on cardiovascular, cerebrovascular, and respiratory homeostasis during these procedures.

METHODS

Physiological data were recorded during the whole surgical procedure in 31 consecutive patients who underwent robotic endoscopic radical prostatectomy under general anaesthesia. Heart rate, mean arterial pressure, central venous pressure, Sp(o(2)), Pe'(co(2)), P(Plat), tidal volume, compliance, and minute ventilation were monitored and recorded. Arterial samples were obtained to determine the arterial-to-end-tidal CO(2) tension gradient. Continuous regional cerebral tissue oxygen saturation (Sct(o(2))) was determined by near-infrared spectroscopy.

RESULTS

Although patients were in the Trendelenburg position, all variables investigated remained within a clinically acceptable range. Cerebral perfusion pressure (CPP) decreased from 77 mm Hg at baseline to 71 mm Hg (P=0.07), and Sct(o(2)) increased from 70% to 73% (P<0.001). Pe'(co(2)) increased from 4.12 to 4.79 kPa (P<0.001) and the arterial-to-Pe'(co(2)) tension difference increased from 1.06 kPa in the normal position to a maximum of 1.41 kPa (P<0.001) after 2 h in the Trendelenburg position.

CONCLUSIONS

The combination of the prolonged steep Trendelenburg position and CO(2) pneumoperitoneum was well tolerated. Haemodynamic and pulmonary variables remained within safe limits. Regional cerebral oxygenation was well preserved and CPP remained within the limits between which cerebral blood flow is usually considered to be maintained by cerebral autoregulation.

Interhemispheric synchrony in visual cortex and abnormal postnatal visual experience

The question of whether neural synchrony may be preserved in adult mammalian visual cortex despite abnormal postnatal visual experience was investigated by combining anatomical and computational approaches. Single callosal axons in visual cortex of early monocularly deprived (MD) adult cats were labeled anterogradely with biocytin in vivo and reconstructed in 3D. Spike propagation was then orthodromically simulated within each of these axons with NEURON software. Data were systematically compared to those previously obtained in normally reared (NR) adult cats with comparable approaches. The architecture of the callosal axons in MD animals differed significantly from the NR group, with longer branches and first nodes located deeper below the cortex. But, surprisingly, simulation of spike propagation demonstrated that transmission latencies of most spikes remained inferior to 2 ms, like the NR group. These results indicate that synchrony of neural activity may be preserved in adult visual cortex despite abnormal postnatal visual experience. According to the temporal binding hypothesis, this also indicates that the necessary timing for visual perception is present despite anatomical abnormalities in visual cortex.

[Endoscopic treatment of pituitary adenomas]

The endoscopic approach is increasingly used for surgical treatment of pituitary adenomas. Early outcome is generally excellent, especially in experienced hands, and particularly for non invasive tumors. Treatment of these patients requires multidisciplinary collaboration among endocrinologists, radiologists and neurosurgeons.

Perioperative blood glucose management in patients undergoing tumor hepatectomy

STUDY OBJECTIVE

To determine whether our institutional insulin management (modified Atlanta) protocol is efficient and safe in controlling blood glucose levels in the perioperative period in surgical patients undergoing tumor hepatectomy.

DESIGN

Retrospective study.

SETTING

Large community hospital.

PATIENTS

20 consecutive patients undergoing liver resection for hepatocellular carcinoma, liver metastasis, or other hepatobiliary tumors.

INTERVENTIONS AND MEASUREMENTS

All patients continuously received intravenous glucose (5% dextrose in water, one mL/kg/hr); insulin was administered according to a strict algorithm, and dose adjustments were based on measurements of whole-blood glucose intraoperatively at one-hour intervals, and in the intensive care unit (ICU). Lower and upper blood glucose limits were set at 85 mg/dL and 110 mg/dL, respectively, in the operating room (OR). In the ICU, lower and upper limits were 90 mg/dL and 140 mg/dL, respectively.

MAIN RESULTS

Intraoperatively, 51.3% of measurements were within the target range. In the ICU, 75.2% of measurements showed a blood glucose level of 90 - 140 mg/dL. Two of 78 (2.6%) and two of 363 (0.5%) measurements had a blood glucose level < 70 mg/dL in the OR and ICU, respectively. The lowest blood glucose levels were 65 mg/dL (OR) and 66 mg/dL (ICU).

CONCLUSIONS

The modified Atlanta protocol is efficient and safe in controlling blood glucose levels in the perioperative period of hepatic tumor resection. Because of decreased insulin needs in the ICU, the use of a more liberal algorithm successfully reduced the risk of hypoglycemia.

Tight perioperative glucose control is associated with a reduction in renal impairment and renal failure in non-diabetic cardiac surgical patients

Introduction

Acute renal failure after cardiac surgery increases in-hospital mortality. We evaluated the effect of intra- and postoperative tight control of blood glucose levels on renal function after cardiac surgery based on the Risk, Injury, Failure, Loss, and End-stage kidney failure (RIFLE) criteria, and on the need for acute postoperative dialysis.

Methods

We retrospectively analyzed two groups of consecutive patients undergoing cardiac surgery with cardiopulmonary bypass between August 2004 and June 2006. In the first group, no tight glycemic control was implemented (Control, n = 305). Insulin therapy was initiated at blood glucose levels > 150 mg/dL. In the group with tight glycemic control (Insulin, n = 745), intra- and postoperative blood glucose levels were targeted between 80 to 110 mg/dL, using the Aalst Glycemia Insulin Protocol. Postoperative renal impairment or failure was evaluated with the RIFLE score, based on serum creatinine, glomerular filtration rate and/or urinary output. We used the Cleveland Clinic Severity Score to compare the predicted vs observed incidence of acute postoperative dialysis between groups.

Results

Mean blood glucose levels in the Insulin group were lower compared to the Control group from rewarming on cardiopulmonary bypass onwards until ICU discharge (p < 0.0001). Median ICU stay was 2 days in both groups. In non-diabetics, strict perioperative blood glucose control was associated with a reduced incidence of renal impairment (p = 0.01) and failure (p = 0.02) scoring according to RIFLE criteria, as well as a reduced incidence of acute postoperative dialysis (from 3.9% in Control to 0.7% in Insulin; p < 0.01). The 30-day mortality was lower in the Insulin than in the Control group (1.2% vs 3.6%; p = 0.02), representing a 70% decrease in non-diabetics (p < 0.05) and 56.1% in diabetics (not significant). The observed overall incidence of acute postoperative dialysis was adequately predicted by the Cleveland Clinic Severity Score in the Control group (p = 0.6), but was lower than predicted in the Insulin group (1.2% vs 3%, p = 0.03).

Conclusions

In non-diabetic patients, tight perioperative blood glucose control is associated with a significant reduction in postoperative renal impairment and failure after cardiac surgery according to the RIFLE criteria. In non-diabetics, tight blood glucose control was associated with a decreased need for postoperative dialysis, as well as 30-day mortality, despite of a relatively short ICU stay.

Dynamic tight glycemic control during and after cardiac surgery is effective, feasible, and safe

BACKGROUND

Tight blood glucose control reduces mortality and morbidity in critically ill patients, but intraoperative glucose control during cardiac surgery is often difficult, and risks hypoglycemia. In this study, we evaluated the safety and efficacy of a nurse-driven insulin protocol (the Aalst Glycemia Insulin Protocol) for achieving a target glucose level of 80-110 mg/dL during cardiac surgery and in the intensive care unit (ICU).

METHODS

We included 483 nondiabetics and 168 diabetics scheduled for cardiac surgery with cardiopulmonary bypass. To anticipate rapid perioperative changes in insulin requirement and/or sensitivity during surgery, we developed a dynamic algorithm presented in tabular form, with rows representing blood glucose ranges and columns representing insulin dosages based on the patients' insulin sensitivity. The algorithm adjusts insulin dosage based on blood glucose level and the projected insulin sensitivity (e.g., reduced sensitivity during cardiopulmonary bypass and normalizing sensitivity after surgery).

RESULTS

A total of 18,893 blood glucose measurements were made during and after surgery. During surgery, the mean glucose level in nondiabetic patients was within targeted levels except during (112 +/- 17 mg/dL) and after rewarming (113 +/- 19 mg/dL) on cardiopulmonary bypass. In diabetics, blood glucose was decreased from 121 +/- 40 mg/dL at anesthesia induction to 112 +/- 26 mg/dL at the end of surgery (P < 0.05), with 52.9% of patients achieving the target. In the ICU, the mean glucose level was within targeted range at all time points, except for diabetics upon ICU arrival (113 +/- 24 mg/dL). Of all blood glucose measurements (operating room and ICU), 68.0% were within the target, with 0.12% of measurements in nondiabetics and 0.18% in diabetics below 60 mg/dL. Hypoglycemia < 50 mg/dL was avoided in all but four (0.6%) patients (40 mg/dL was the lowest observed value).

CONCLUSIONS

The Aalst Glycemia Insulin Protocol is effective for maintaining tight perioperative blood glucose control during cardiac surgery with minimal risk of hypoglycemia.

Safety and tolerability of single intravenous doses of sugammadex administered simultaneously with rocuronium or vecuronium in healthy volunteers

BACKGROUND

Sugammadex rapidly reverses rocuronium- and vecuronium-induced neuromuscular block. To investigate the effect of combination of sugammadex and rocuronium or vecuronium on QT interval, it would be preferable to avoid the interference of anaesthesia. Therefore, this pilot study was performed to investigate the safety, tolerability, and plasma pharmacokinetics of single i.v. doses of sugammadex administered simultaneously with rocuronium or vecuronium to anaesthetized and non-anaesthetized healthy volunteers.

METHODS

In this phase I study, 12 subjects were anaesthetized with propofol/remifentanil and received sugammadex 16, 20, or 32 mg kg(-1) combined with rocuronium 1.2 mg kg(-1) or vecuronium 0.1 mg kg(-1); four subjects were not anaesthetized and received sugammadex 32 mg kg(-1) with rocuronium 1.2 mg kg(-1) or vecuronium 0.1 mg kg(-1) (n=2 per treatment). Neuromuscular function was assessed by TOF-Watch SX monitoring in anaesthetized subjects and by clinical tests in non-anaesthetized volunteers. Sugammadex, rocuronium, and vecuronium plasma concentrations were measured at several time points.

RESULTS

No serious adverse events (AEs) were reported. Fourteen subjects reported 23 AEs after study drug administration. Episodes of mild headache, tiredness, cold feeling (application site), dry mouth, oral discomfort, nausea, increased aspartate aminotransferase and gamma-glutamyltransferase levels, and moderate injection site irritation were considered as possibly related to the study drug. The ECG and vital signs showed no clinically relevant changes. Rocuronium/vecuronium plasma concentrations declined faster than those of sugammadex.

CONCLUSIONS

Single-dose administration of sugammadex 16, 20, or 32 mg kg(-1) in combination with rocuronium 1.2 mg kg(-1) or vecuronium 0.1 mg kg(-1) was well tolerated with no clinical evidence of residual neuromuscular block, confirming that these combinations can safely be administered simultaneously to non-anaesthetized subjects. Rocuronium and vecuronium plasma concentrations decreased faster than those of sugammadex, reducing the theoretical risk of neuromuscular block developing over time.

Muscle relaxation does not influence venous oxygen saturation during cardiopulmonary bypass

STUDY OBJECTIVE

To examine whether the omission of neuromuscular blocking drugs during cardiopulmonary bypass (CPB) is associated with increased anesthetic requirements, higher frequency of intraoperative movements, and lower venous oxygen saturation (SvO(2)).

DESIGN

Prospective, randomized study.

SETTING

Large community hospital.

PATIENTS

30 ASA physical status III and IV patients scheduled for cardiac surgery.

INTERVENTIONS

Patients were randomized to one of two groups: group 1 (n = 15) received a 3xED(95) bolus dose of cisatracurium at induction and thereafter no more neuromuscular blocking drug; group 2 (n = 15) received a continuous infusion of cisatracurium during the entire procedure.

INTERVENTIONS

Both groups received a standardized anesthetic with bispectral index-guided propofol target-controlled infusion and a remifentanil infusion steered by hemodynamic changes. Venous oxygen saturation was continuously determined during CPB.

MEASUREMENTS AND MAIN RESULTS

Propofol consumption was 5.4 +/- 1.7 and 4.4 +/- 1.0 mg/(kg/h) in groups 1 and 2, respectively (P = 0.07). Remifentanil consumption was 0.15 +/- 0.05 and 0.17 +/- 0.05 mug/(kg/min) in groups 1 and 2, respectively (P = 0.19). In groups 1 and 2, no patient recalled any intraoperative phenomena; none moved or had diaphragmatic contractions. During CPB, SvO(2) was 81.3 +/- 3.2% (76%-85%) in group 1 and 80.6 +/- 3.1% (73%-85%) in group 2 (P = 0.53).

CONCLUSIONS

Omitting the continuous administration of neuromuscular blocking drugs during CPB did not increase anesthetic requirements. No intraoperative movements occurred, nor was there decreased SvO(2).

Preinduction glycemia and body mass index are important predictors of perioperative insulin management in patients undergoing cardiac surgery

STUDY OBJECTIVE

To investigate whether preinduction glucose is an important predictor for perioperative insulin management in patients undergoing cardiac surgery.

DESIGN

Prospective cohort study.

SETTING

Large community hospital.

PATIENTS

80 consecutive patients scheduled for cardiac surgery.

INTERVENTIONS

Patients were subdivided into those with a preinduction blood glucose of 110 mg/dL or lower with or without history of diabetes (group 1) and those with a preinduction blood glucose of above 110 mg/dL with or without history of diabetes (group 2). In group 1, there were no known diabetics. In group 2, 31% (11/35) had diabetes (group 2DM), while 24/35 (69%) did not (group 2NDM). An insulin infusion was started intraoperatively and adjusted according to a strict protocol in order to maintain normoglycemia (80-110 mg/dL) until discharge from intensive care.

MEASUREMENTS AND MAIN RESULTS

In patients with preinduction glucose above 110 mg/dL, whether or not previously treated for diabetes, perioperative insulin requirements were higher, and intraoperative insulin management was more difficult than in those with lower preinduction glucose. In patients with a preinduction glucose above 110 mg/dL, hospital stay was longer, and inhospital mortality was significantly higher than in those with lower preinduction glucose. Multivariate analyses showed that preinduction glycemia was a good predictor of intraoperative insulin consumption, as was the body mass index (BMI) for intensive care and total insulin needs.

CONCLUSIONS

In cardiac surgical patients with a preinduction glucose above 110 mg/dL, even if diabetes was not previously suspected, perioperative insulin requirements were higher, and intraoperative insulin management is more difficult than in those with a preinduction glucose 110 mg/dL or lower. Preinduction glycemia and BMI are good predictors of perioperative insulin management. Preinduction glycemia above 110 mg/dL predicts difficult perioperative glucose control and, moreover, that a preinduction blood glucose of 110 mg/dL or lower is associated with less insulin need.

Mechanical Stress Activates Platelets at a Subhemolysis Level: An In Vitro Study

A feasibility study is performed to quantify sheep platelets (PLTs) and to identify the relationship between PLT count and hemolysis as a consequence of mechanical stress. Six adult, healthy Dorset sheep have been used for in vitro blood sampling test procedures in a hemoresistometer device (HRM). In each experiment, blood of the same animal was exposed to six different shear rates. Free hemoglobin levels and PLT count for each shear rate were detected. In all animals (A-F), hemolysis increased significantly between the shear rates of 2325 and 3100/s (P < 0.05) and the mean PLT count dropped immediately (contact, low shear) 40% in the beginning, between the shear rates of 0 and 775/s (P < 0.05). PLT count increased slightly as soon as hemolysis started. At higher shear rates, hemolysis increased and PLTs reduced further. Precise counting of PLTs indicates that PLTs are consumed dramatically at very low shear (by contact) and further by applied mechanical stress when hemolysis is obvious. A repetition of these tests with human blood could indicate species differences.

Avoiding vascular complications during minimally invasive, totally endoscopic intracardiac surgery

OBJECTIVE

The introduction of minimally invasive valve surgery has been associated with an increased use of peripheral vessel cannulation in cardiopulmonary bypass. These techniques are associated with potential problems at the aorta or cannulation sites. The goal of this study was to review and describe our current practice to avoid vascular problems during cannulation of peripheral vessels.

METHOD

Data collection for this study was done retrospectively by reviewing the files of all patients who underwent a minimally invasive mitral and/or tricuspid surgery in our institution from 1997 to the end of 2005.

RESULTS

Our cohort of 978 patients revealed an overall rate of peripheral vascular complication of 1.0% with 44.4% presenting at the time of the surgery and 63.6% at long-term follow-up. Acute peripheral vascular problems were treated by simple graft replacement of the diseased segment in most cases. All aortic complications happened at the time of the surgery (complication rate of 0.9%) with 60% of them associated with cannulation problems. Most patients were treated by replacement of the ascending aorta.

CONCLUSIONS

A systematic and careful approach is associated with a low risk of vascular problems. Prevention and planning with precise surgical technique remain the main conditions to safely use peripheral cannulation and perfusion for minimally invasive mitral valve surgery.

Minimally invasive aortic root replacement: a bridge too far?

AIM

Minimally invasive aortic valve surgery has been studied widely with outcomes comparable or better than standard sternotomy. We recently reported on decreased blood loss, cross clamp time and length of hospital stay when compared to conventional full sternotomy. We expanded the indication to aortic root surgery and report here our 8 years experience.

METHODS

From December 1997 to November 2005, 35 patients (mean age 51.3+/-15 years) underwent aortic root replacement, through a partial upper J-sternotomy. A homograft was implanted in 26 (74.3%) patients; the remainder received a valved (4 bioprosthesis, 5 mechanical) conduit. Mean preoperative euroscore was 7+/-2.7 and mean predicted mortality was 11.5+/-13.8%. Mean and median follow-up time was 51+/-31 and 66 months, respectively.

RESULTS

Mean aortic cross clamp and cardiopulmonary bypass time were 126+/-25 and 182+/-61 min respectively. Revision for bleeding was necessary in 1 (2.9%) patient. Mean extubation time was 10.4+/-4.8 hours. No postoperative strokes occurred. Intensive care unit stay ranged from 1 to 42 days (2.7+/-7.4 days, median 1). There were 3 (8.5%) early deaths (sepsis, multi-organ failure and low cardiac output) and 2 late non-cardiac deaths. Hospital morbidity included acute renal failure (n=3), pacemaker implantation (n=3), and prolonged ventilation (n=3). Eleven (31.4%) patients experienced atrial fibrillation. No other reoperations were performed. Actuarial survival at 99 months was 74.4% (n=30).

CONCLUSIONS

Our results indicate that minimally invasive aortic root replacement is a challenging but feasible procedure with a lower observed mortality than predicted mortality. We continue to perform this procedure in good risk patients.

Intraoperative Severity Assessment of Coronary Artery Stenosis in Patients at Risk: The Role of Transesophageal Echocardiography

A 71-yr-old male was scheduled for infrarenal abdominal aortic aneurysm repair. Although he had only minor clinical predictors for increased perioperative cardiovascular risk with >4 estimated metabolic equivalents for activities, intraoperative transesophageal echocardiography revealed an abnormal maximal-to-prestenotic blood flow velocity ratio in the left main coronary artery. Postoperatively, a severe distal left main coronary artery stenosis was confirmed with coronary angiography. Understanding the flow velocity patterns in the coronary arteries helps the anesthesiologist to detect coronary lesions with transesophageal echocardiography.

Postoperative Residual Paralysis in Outpatients Versus Inpatients

Postoperative residual paralysis is an important complication of the use of neuromuscular blocking drugs. In this prospective study, the incidence of residual paralysis detected as a train-of-four response <90% was less frequent in surgical outpatients (38%) than inpatients (47%) (P = 0.001). This might have been the result of the more frequent use of mivacurium for outpatients. Before undertaking tracheal extubation, the anesthesiologists had applied clinical criteria (outpatients, 49%; inpatients, 45%), pharmacological reversal (26%, 25%), neuromuscular transmission monitoring (12%, 11%), or a combination of these. None of these measures seemed to reduce the incidence of residual paralysis except for quantitative train-of-four monitoring. Postoperatively, eight individual clinical tests or a sum of these tests were also unable to predict residual paralysis by train-of-four. Although the incidence of residual paralysis was less frequent in surgical outpatients, predictive criteria were not evident.

Glycopyrrolate during sevoflurane–remifentanil-based anaesthesia for cardiac catheterization of children with congenital heart disease

BACKGROUND

Remifentanil is recommended for use in procedures with painful intraoperative stimuli but minimal postoperative pain. However, bradycardia and hypotension are known side-effects. We evaluated haemodynamic effects of i.v. glycopyrrolate during remifentanil-sevoflurane anaesthesia for cardiac catheterization of children with congenital heart disease.

METHODS

Forty-five children undergoing general anaesthesia with remifentanil and sevoflurane were randomly allocated to receive either saline, glycopyrrolate 6 microg kg(-1) or glycopyrrolate 12 microg kg(-1). After induction of anaesthesia with sevoflurane, i.v. placebo or glycopyrrolate was administered. An infusion of remifentanil at the rate of 0.15 microg kg(-1) min(-1) was started, sevoflurane continued at 0.6 MAC and cisatracurium 0.2 mg kg(-1) was given. Heart rate (HR) and non-invasive arterial pressures were monitored and noted every minute for the first 10 min and then every 2.5 min for subsequent maximum of 45 min.

RESULTS

Baseline HR [mean (SD)] of 117 (20) beats min(-1) decreased significantly from 12.5 min onwards after starting the remifentanil infusion in the control group [106 (18) at 12.5 min and 99 (16) beats min(-1) at 45 min]. In the groups receiving glycopyrrolate, no significant decrease in HR was noticed. Glycopyrrolate at 12 microg kg(-1) induced tachycardia between 5 and 9 min after administration. Systolic and diastolic arterial pressures decreased gradually, but there were no significant differences in the pressures between groups.

CONCLUSION

I.V. glycopyrrolate 6 microg kg(-1) prevents bradycardia during general anaesthesia with remifentanil and sevoflurane for cardiac catheterization in children with congenital heart disease. Administering 12 microg kg(-1) of glycopyrrolate temporarily induces tachycardia and offers no additional advantage.

Multivessel distal sutureless off-pump coronary artery bypass grafting procedure using magnetic connectors

Proximal anastomotic devices for beating heart coronary artery bypass grafting (CABG) have been developed to avoid ascending aortic manipulation. Distal anastomotic devices may become an extremely useful tool to assist in enabling minimally invasive (robotic) multivessel CABG. As a transition phase toward this ultimate goal we have been using a distal anastomotic device for the left internal mammary artery-left anterior descending artery (LIMA-LAD) anastomosis. In addition we recently performed two off-pump coronary artery bypass procedures that were distally completely sutureless.

Large bolus dose vs. continuous infusion of cisatracurium during hypothermic cardiopulmonary bypass surgery

BACKGROUND AND OBJECTIVE

We investigated whether a high bolus dose of cisatracurium (8x ED95) given at induction can provide muscle relaxation for the major part of a cardiac procedure with hypothermic cardiopulmonary bypass, avoid important postoperative residual curarization and cause no waste of product.

METHODS

Twenty patients were randomly assigned either to Group 1 (n = 10) or Group 2 (n = 10). Those in Group 1 were given cisatracurium in a high bolus dose (0.4 mg kg(-1)). Those in Group 2 received cisatracurium 0.1 mg kg(-1) at induction followed after 30 min by a continuous infusion of cisatracurium. As an escape medication in case of patient movement, a bolus dose of cisatracurium 0.03 mg kg(-1) was given.

RESULTS

In Group 1 (large cisatracurium bolus dose), the clinical duration of effect (until T1/T0 = 25%) was 110 min. Six of 10 patients in Group 1 required additional boluses of cisatracurium intraoperatively. Four of these six had received an additional bolus near the end of surgery and had a train-of-four (TOF) ratio = 0 at the end. The other four patients in Group 1 had a final TOF ratio >0.9. In Group 2 (continuous cisatracurium infusion), only two patients had a TOF ratio >0.9 at the end of surgery, no patient moved and none received additional boluses. The total amount of cisatracurium used in the bolus and infusion Groups was 34.5 +/- 7.8 and 21.3 +/- 5.7 mg, respectively (P = 0.0004).

CONCLUSIONS

For continued neuromuscular block during hypothermic cardiac surgery, a high bolus dose of cisatracurium appears to be safe, although it is not an alternative to a continuous infusion, as its neuromuscular blockade does not cover the intraoperative period and a high incidence of movements occurs. In the patients who received a high bolus dose of cisatracurium, postoperative residual curarization appeared after additional boluses had been given. The consumption of cisatracurium by high bolus was significantly greater than with continuous infusion.

Lipoprotein lipase activity and common gene variants in severely hypertriglyceridemic patients with and without diabetes

OBJECTIVES

In severe type IV hypertriglyceridemia (triglyceride levels >10 g/l), it is yet unknown whether lipoprotein lipase (LPL) differs according to the presence or not of diabetes.

METHODS

We compared LPL activity and the presence of four common variants in the LPL gene (Asp 9 Asn (exon 2), Gly 188 Glu (exon 5), Asn 291 Ser (exon 6) and Ser 447 Ter (exon 9)) in a group of 34 patients of whom 17 presented diabetes mellitus.

RESULTS

Maximum triglyceride, cholesterol levels and distribution of apolipoprotein E phenotypes did not differ between the two subgroups. Mean post-heparin LPL activity was lower in non-diabetic compared to diabetic patients (9.74 vs. 12.98 micromol FFA/ml/h, p=0.033). Four patients were carrying a mutation in exon 9 (1 non-diabetic), 6 patients in exon 2 (4 non-diabetic) and 1 patient in the non-diabetic subgroup in exon 5. All mutations were at the heterozygous state.

CONCLUSION

We found that LPL activity was lower in type IV hyperlipidemia in the absence of diabetes. Genetic defects in the LPL gene that could lead to this lower LPL tended to be more frequently observed in patients without diabetes. These data suggest that the pathomechanisms which contribute to severe type IV hyperlipidemia are different according to the presence or not of diabetes.

Intermittent nitric oxide combined with intravenous dipyridamole in a piglet model of acute pulmonary hypertension

Continuous administration of inhaled nitric oxide is now widely used as a potent and selective pulmonary vasodilator. We have evaluated the effects of IV dipyridamole, a cyclic guanosine monophosphate (cGMP) phosphodiesterase inhibitor, on the magnitude and duration of action of inhaled nitric oxide (NO)-mediated pulmonary vasodilation. We hypothesized that inhibition of cGMP degradation could augment and prolong the pulmonary vasodilating effects of NO and allow for intermittent NO inhalation. In eight anesthetized and mechanically ventilated piglets, IV U-46619, a thromboxane A(2) analog, was used to induce pulmonary hypertension. The effects of 2, 5, and 10 ppm of NO, delivered during 4 min for each concentration and followed by a 10-min NO-free interval after each NO concentration, were evaluated without and with dipyridamole. Pulmonary vascular resistance decreased from 825 +/- 49 dynes. s. cm(-5) (U-46619) to 533 +/- 48 dynes. s. cm(-5) (10 ppm NO) (P < 0.05 versus U-46619) and 396 +/- 42 dynes. s. cm(-5) (dipyridamole 10 microg kg-1x min-1 and 10 ppm NO) (P <0.05 versus NO), and cardiac output increased from 1.93 +/- 0.09 L/min to 2.03 +/- 0.13 L/min and 2.60 +/- 0.30 L/min (P < 0.05 versus NO). Mean arterial blood pressure decreased from 90 +/- 5 mm Hg (10 ppm NO) to 75 +/- 3 mm Hg (dipyridamole plus 10 ppm NO) (P < 0.01). The pulmonary vasodilation obtained with NO alone could be prolonged from 12 to 42 min when inhaled NO was combined with IV dipyridamole, accounting for a time-weighted reduction in NO exposure by 72%. We conclude that dipyridamole augments the effects of NO on right ventricular afterload, allows for intermittent NO inhalation, and can significantly reduce exposure to NO.

IMPLICATIONS

IV dipyridamole prolongs the action of inhaled nitric oxide (NO) in a piglet model of acute pulmonary hypertension. Intermittent NO inhalation combined with IV dipyridamole decreases pulmonary artery pressure for a prolonged period of time and reduces exposure to NO.

Beta-adrenergic blocking drugs in the perioperative period

During the last years increasing evidence has indicated that patients at risk for coronary artery disease may benefit from beta-adrenergic blocking therapy in the perioperative setting. It has been demonstrated that even a relatively brief treatment with beta-adrenergic blocking drugs decreases the incidence of perioperative myocardial ischemia. Even more important is the observation that this reduction in perioperative ischemic events ultimately results in a decrease in long term cardiac morbidity and mortality. Despite overwhelming evidence on the beneficial effects of beta-adrenergic blocking in patients with coronary artery disease, many clinicians still feel some reluctance to use this type of drugs in the perioperative period. We organized a meeting to search for the major objectives that keep anesthetists from implementing prophylactic beta blocking therapy in their daily clinical practice. In this brief review we summarize the results of this meeting and discuss the current knowledge on this subject.

Successful treatment of acute dissection of the donor aorta after orthotopic heart transplantation

Acute aortic dissection is one of the rare aortic complications that occur after orthotopic heart transplantation. We report the second case of successful surgical treatment of aortic dissection confined to the donor aorta in a recipient of an orthotopic cardiac allograft. A 68-year-old patient was admitted with chest pain and shortness of breath 7 years after orthotopic heart transplantation. He previously had undergone twice coronary artery bypass grafting. Echocardiography revealed acute dissection of the donor aorta. The patient underwent urgent Bentall procedure with a prosthetic conduit. The post-operative course was uneventful. The heart donor was a 40-year-old man with known arterial hypertension and who had received long-term ergotamine tartrate therapy for migraine. This case demonstrates that heart-transplant recipients with arterial hypertension and donor-related risk factors are prone to aortic complications and require careful follow-up.

The midwall stress-velocity relationship during manipulation of afterload

Despite providing a physiological correction, measurements of contractility using the midwall stress-velocity relationship still show evidence of an unexplained hypercontractile state in some children. We investigated if by using midwall shortening indexes, the known overestimation of contractility at low afterload could be prevented. In 12 piglets (5 or 6 weeks old), afterload was manipulated by balloon occlusion of the descending aorta and infusion of sodium nitroprusside up to 5 mg/kg/min, and left ventricular function was measured using multiple variables. The regression line between the echocardiographically derived midwall velocity of circumferential fiber shortening and end systolic wall stress differed from the regression line of the endocardial stress-velocity relationship. Although the midwall regression line was almost horizontal (or afterload independent) for end systolic wall stress values of more than 30 g/cm2, the slope was still steeper below a certain point of afterload. The increased midwall velocity of fiber shortening at low afterload is comparable to the endocardial stress-velocity relationship and could account for the pseudo-hypercontractile state found in some children.

An experimental model of coronary anastomosis without suturing

OBJECTIVE

The aim of the study is to explore the feasibility and mid-term patency of an easier anastomotic technique for Minimally Invasive Direct Coronary Bypass Grafting (MIDCAB).

METHODS

Eight mongrel dogs (+/-15 kg) underwent direct anastomosis between the left internal thoracic artery (LITA) and the left anterior descending coronary artery (LAD) via inferior sternotomy on the beating heart. After positioning the graft, the distal part of the LAD was opened to allow retrograde filling of the LITA-graft. The anastomosis was secured by the use of biological glue (BioGlue, Cryolife, Marietta, GA, USA). No intravascular suture material was used. Ischemic time averaged 6 min. The proximal LAD was occluded upstream the arteriotomy. All survivors were angiographically controlled for patency after 6-8 weeks. Consequently, four dogs were sacrificed after 6 weeks and the remaining after 3 months for anatomo-pathological and histological examination by light and electron microscopy of the anastomotic site.

RESULTS

All procedures were successful except for one animal that died of uncontrollable bleeding at the anastomotic site. Another sustained post-operative transmural anterior myocardial infarction due to a late graft occlusion. All angiographically controlled grafts were patent with two vascular strings near the anastomotic site. Histology showed early macrophage infiltration into the glue. At post-mortem examination, new endothelialization was noticed in 80% of the cases. However, ultrastructural examination detected marked differences in endothelial fibroblastic lining compared to normal histology.

CONCLUSIONS

Good mid-term permeability of the LITA grafts was observed in this new anastomotic technique for MIDCAB in the canine model. Although neo-endothelialization was present in most cases, ultrastructural differences were noticed after 3 months in the neo-intima compared to normal.

Intravenous dipyridamole enhances the effects of inhaled nitric oxide and prevents rebound pulmonary hypertension in piglets

Inhaled nitric oxide (NO) is increasingly used in the treatment of pulmonary hypertension, despite its potential toxicity and the risk of life-threatening rebound pulmonary hypertension upon its discontinuation. We investigated whether i.v. dipyridamole, a cGMP phosphodiesterase inhibitor, increased the effects of inhaled NO and prevented rebound pulmonary hypertension. In 14 anesthetized and mechanically ventilated piglets, pulmonary hypertension was induced with U-46619, a thromboxane A(2) analogue. Response to NO and rebound pulmonary hypertension were evaluated without and with i.v. dipyridamole. Low-dose dipyridamole (10 micro g/kg/min) increased cardiac output and augmented the effects of inhaled NO on pulmonary vascular resistance, with marginal additive effect on mean pulmonary artery pressure. Pulmonary vascular resistance decreased from 904 to 511 (20 parts per million NO) (p < 0.0005) and 358 dyne s cm(-5) (20 parts per million NO + dipyridamole) (p < 0.001 versus NO alone), and mean pulmonary artery pressure decreased from 29.0 to 20.5 (p < 0.0001) and 19.3 mm Hg (NS versus NO), respectively. Mean arterial pressure decreased from 85 to 74 mm Hg (dipyridamole + NO) (p < 0.01). High-dose dipyridamole (100 micro g/kg/min) with inhaled NO reduced pulmonary vascular resistance to 334 dyne s cm(-5) but also decreased mean arterial pressure to 57 mm Hg. Eight piglets developed rebound pulmonary hypertension. Two died of acute right ventricular failure and, in five, rebound pulmonary hypertension was prevented by low-dose dipyridamole. In conclusion, low-dose i.v. dipyridamole augments the effects of inhaled NO on right ventricular afterload with moderate changes in systemic hemodynamics, and can prevent rebound pulmonary hypertension.

Remifentanil infusion for cardiac catheterization in children with congenital heart disease

BACKGROUND

Cardiac catheterization of children with congenital heart disease is increasingly being performed under general anesthesia. Haemodynamic stability during anesthesia and fast and adequate recovery after the procedure is crucial in these patients. We performed a pilot study to evaluate hemodynamic stability when using remifentanil for anesthesia during cardiac catheterization. We also evaluated extubation times and recovery characteristics.

METHODS

In a randomized, prospective, double-blind study 30 children (aged 1.5-20 months) received a continuous infusion of either 0.2 (group 0.2) or 0.3 microg/kg/min remifentanil (group 0.3) as part of a balanced anesthesia with 0.6 MAC sevoflurane. Heart rate, noninvasive arterial blood pressure, end tidal CO2 and pulse oxymetry were monitored throughout the procedure. Extubation times were noted, and recovery from anesthesia was evaluated using Aldrete scores.

RESULTS

: Haemodynamic response to intubation was well blunted in both groups. No significant changes in hemodynamic variables were noted from induction of anesthesia until 10 min after intubation. From then on there was a decrease in HR and systolic arterial pressure, which remained significant throughout the procedure in both groups. Extubation times were similar in both groups: 7.3 min (2,1) in group 0.2 vs. 6.6 min (2,1) in group 0.3 (NS). The number of patients with an Aldrete score of nine or more was 14 (group 0.2) vs. 15 (group 0.3), 10 min after extubation (NS).

CONCLUSION

Both dose regimens of remifentanil provided stable hemodynamic conditions during anesthesia for cardiac catheterization of children with congenital heart disease and allowed for rapid and adequate recovery.

Comparison of octreotide acetate LAR and lanreotide SR in patients with acromegaly

BACKGROUND AND OBJECTIVE

The most effective option for the medical treatment of patients with acromegaly is the use of somatostatin analogues. Long-acting depot formulations for intramuscular injection of two somatostatin analogues have recently become available: octreotide acetate LAR (Sandostatin LAR, Novartis Pharma AG) and lanreotide SR (Somatuline, Ipsen Biotech). We wished to compare efficacy of octreotide LAR and lanreotide SR in acromegalic patients.

PATIENTS AND METHODS

A group of 125 patients with acromegaly (67 females; mean age, 47 years; 59 patients had previous pituitary irradiation) from 26 medical centres in France, Spain and Germany were studied. Before the study, all patients had been treated with intramuscular injections of lanreotide SR (mean duration, 26 months) at a dose of 30 mg which was injected every 10 days in 64 and every 14 days in 61 patients, respectively. All patients were switched from lanreotide SR to intramuscular injections of 20 mg of octreotide LAR once monthly for three months. In order to obtain efficacy and safety data of lanreotide SR under study conditions, it was decided to randomly assign at day 1, in a 3 : 1 ratio, the time point of the treatment switch; 27 of the patients were randomly assigned to continue the lanreotide SR treatment for the first 3 months of the study (group A); they were on octreotide LAR 20 mg from month 4-6. The other 98 patients were assigned to be switched to treatment with octreotide LAR 20 mg at day 1 (group B). In group B patients, octreotide LAR treatment was continued until month 6, with an adjustment of the dose based on GH levels obtained at month 3.

RESULTS

The mean GH concentration decreased from 9.6 +/- 1.3 mU/l at the last evaluation on lanreotide SR to 6.8 +/- 1.0 mU/l after three injections of octreotide LAR (P < 0.001). The percentages of patients with mean GH values < or = 6.5 mU/l (2.5 microg/l) and < or = 2.6 mU/l (1.0 microg/l) at the last evaluation on lanreotide SR were 54% and 14%, and these values increased after 3 months treatment with octreotide LAR to 68% and 35% (P < 0.001), respectively. IGF-I levels were normal in 48% at the last evaluation on lanreotide SR and in 65% after 3 months on octreotide LAR (P < 0.001). Patients with pre-study pituitary irradiation had lower mean GH and IGF-I concentrations. But the effects of the treatment change did not differ between the irradiated and the nonirradiated patients. In general both drugs were well tolerated.

CONCLUSION

Octreotide LAR 20 mg administered once monthly was more effective than lanreotide SR 30 mg administered 2 or 3 times monthly in reducing GH and IGF-I in patients with acromegaly.