A decreasing plasma concentration of a toxicologically active metabolite 9-carboxymethoxymethylguanine after dialysis - A potential new clinical biomarker for improving encephalopathy in patients treated with acyclovir

Although acyclovir is a key drug for the treatment of herpes infections, a consciousness disorder known as "acyclovir encephalopathy" is among its side effects. We encountered a patient with encephalopathy and measured the plasma and cerebrospinal fluid concentrations of acyclovir and its toxicologically active metabolite 9-carboxymethoxymethylguanine (CMMG). Before dialysis, cerebrospinal fluid concentrations of acyclovir and CMMG in this patient with a consciousness disorder were approximately 10% and 1%, respectively, of their plasma concentrations. After 3 days of dialysis, plasma CMMG levels decreased to detectable but below quantitative levels (<0.1 μg/mL), resulting in normal consciousness. These results suggest that decreasing plasma CMMG concentration could be one of clinical biomarkers for improving consciousness in patients with encephalopathy associated with acyclovir.

The whole blood transcriptional regulation landscape in 465 COVID-19 infected samples from Japan COVID-19 Task Force

Coronavirus disease 2019 (COVID-19) is a recently-emerged infectious disease that has caused millions of deaths, where comprehensive understanding of disease mechanisms is still unestablished. In particular, studies of gene expression dynamics and regulation landscape in COVID-19 infected individuals are limited. Here, we report on a thorough analysis of whole blood RNA-seq data from 465 genotyped samples from the Japan COVID-19 Task Force, including 359 severe and 106 non-severe COVID-19 cases. We discover 1169 putative causal expression quantitative trait loci (eQTLs) including 34 possible colocalizations with biobank fine-mapping results of hematopoietic traits in a Japanese population, 1549 putative causal splice QTLs (sQTLs; e.g. two independent sQTLs at TOR1AIP1), as well as biologically interpretable trans-eQTL examples (e.g., REST and STING1), all fine-mapped at single variant resolution. We perform differential gene expression analysis to elucidate 198 genes with increased expression in severe COVID-19 cases and enriched for innate immune-related functions. Finally, we evaluate the limited but non-zero effect of COVID-19 phenotype on eQTL discovery, and highlight the presence of COVID-19 severity-interaction eQTLs (ieQTLs; e.g., CLEC4C and MYBL2). Our study provides a comprehensive catalog of whole blood regulatory variants in Japanese, as well as a reference for transcriptional landscapes in response to COVID-19 infection.

Genetic mechanisms influencing COVID-19 susceptibility are not well understood. Here, the authors analyzed whole blood RNA-seq data of 465 Japanese individuals with COVID-19, highlighting thousands of fine-mapped variants affecting expression and splicing of genes, as well as the presence of COVID-19 severity-interaction eQTLs.

Pharmacokinetics of caffeine self-administered in overdose in a Japanese patient admitted to hospital

Background

Caffeine (0.1 g) is used as a central nervous system stimulant and as a nontoxic phenotyping probe for cytochrome P450 1A2. However, an increasing number of suicide attempts by caffeine overdose have been recently reported.

Case presentation

A 25-year-old woman (body weight, 43 kg) who intentionally took an overdose of 5.9 g caffeine as a suicide attempt was emergently admitted to Kyoto Medical Center. The plasma concentrations of caffeine and its primary metabolite, N-demethylated paraxanthine, in the current case were 100 and 7.3 μg/mL, 81 and 9.9 μg/mL, 63 and 12 μg/mL, and 21 and 14 μg/mL, at 12, 20, 30, and 56 h after oral overdose, respectively. The observed apparent terminal elimination half-life of caffeine during days 1 and 2 of hospitalization was 27 h, which is several times longer than the reported normal value. This finding implied nonlinearity of caffeine pharmacokinetics over such a wide dose range, which could affect the accuracy of values simulated by a simplified physiologically based pharmacokinetic model founded on a normal dose of 100 mg. Low serum potassium levels (2.9 and 3.5 mM) on days 1 and 2 may have been caused by the caffeine overdose in the current case.

Conclusions

The patient underwent infusion with bicarbonate Ringer’s solution and potassium chloride and was discharged on the third day of hospitalization despite taking a potentially lethal dose of caffeine. The virtual plasma exposures of caffeine estimated using the current simplified PBPK model were higher than the measured values. The present results based on drug monitoring data and additional pharmacokinetic predictions could serve as a useful guide in cases of caffeine overdose.

Pharmacokinetics of loxoprofen in a self-administered overdose in a Japanese patient admitted to hospital

Background

Loxoprofen is a propionic acid derivative and is the most widely prescribed non-steroidal anti-inflammatory drug in Japan. Loxoprofen is generally considered to be relatively nontoxic.

Case presentation

A 33-year-old man (body weight, 55 kg) who intentionally took an overdose of 100 tablets of loxoprofen (6000 mg) as a suicide attempt was emergently admitted to Kyoto Medical Center. On arrival, the patient was suffering disorders of consciousness. His plasma concentrations of loxoprofen and its reduced trans-alcohol metabolite were 52 and 24 μg/mL, 3.7 and 2.3 μg/mL, 0.81 and 0.54 μg/mL, and 0.015 and 0.011 μg/mL, respectively, at 4, 26, 50, and 121 h after the oral overdose. The observed apparent terminal elimination half-life of loxoprofen during days 1 and 2 of hospitalization was in the range 6–12 h, which is several times longer than the reported normal value. This finding implied nonlinearity of loxoprofen pharmacokinetics over the current 100-fold dose range, which could affect the accuracy of values simulated by a simplified physiologically based pharmacokinetic (PBPK) model founded on data from a normal dose of 60 mg. The reasons for the delayed eliminations from plasma of loxoprofen and its trans-alcohol metabolite in this case are uncertain, but slight renal impairment (low eGFR values) developed on the second and third hospital days and could be a causal factor.

Conclusions

Because the patient’s level of consciousness had gradually improved, he was discharged on the fourth day of hospitalization. The virtual plasma exposures of loxoprofen and its reduced trans-alcohol metabolite estimated using the current simplified PBPK model were lower than the measured values in the overdose case. The present results based on drug monitoring data and pharmacokinetic predictions could serve as a useful guide in cases of loxoprofen overdose.

Pharmacokinetic modeling of over-the-counter drug diphenhydramine self-administered in overdoses in Japanese patients admitted to hospital

Background

Although the over-the-counter H₁ receptor antagonist diphenhydramine is not a common drug of abuse, it was recently recognized as one of the substances causing acute poisoning in patients attempting suicide that led to admissions to our hospital emergency room.

Case presentation

Two patients [women aged 21 and 27 years (cases 1 and 2)] were emergently admitted after intentionally taking overdoses of 900 and 1200 mg diphenhydramine, respectively. The plasma diphenhydramine concentrations in case 1 were 977 and 425 ng/mL at 2.5 and 11.5 h after single oral overdose, and those in case 2 were 1320 and 475 ng/mL at 3 and 18 h after administration, respectively. We set up a simplified physiologically based pharmacokinetic (PBPK) model that was established using the reported pharmacokinetic data for a microdose of diphenhydramine. The two virtual plasma concentrations and the area under the curve (AUC) values extrapolated using the PBPK model were consistent with the observed overdose data. This finding implied linearity of pharmacokinetics over a wide dosage range for diphenhydramine.

Conclusions

The determined plasma concentrations of diphenhydramine of around 1000 ng/mL at ~ 3 h after orally administered overdoses in cases 1 and 2 may not have been high enough to cause hepatic impairment because levels of aspartate aminotransferase and alanine aminotransferase were normal; however, there was an increase in total bilirubin in case 1. Nonetheless, high virtual liver exposures of diphenhydramine were estimated by the current PBPK model. The present results based on drug monitoring data and pharmacokinetic predictions could serve as a useful guide when setting the duration of treatment in cases of diphenhydramine overdose.

Factors influencing the length of emergency room stay and hospital stay in non-fatal bicycle accidents: A retrospective analysis

PURPOSE

Lengthy hospitalization places a burden on patients and healthcare resources. However, the factors affecting the length of hospital stay (LHoS) and length of emergency room stay (LERS) in non-fatal bicycle accidents are currently unclear. We investigated these factors to inform efforts to minimize hospitalization.

METHODS

We performed a retrospective analysis of data from non-fatal injured bicyclists admitted to the Emergency and Critical Care Center at Kyoto Medical Center between January 2012 and December 2016. We measured LHoS, LERS, mechanism of injury, head injury prevalence, polytrauma, operations performed, injury severity score (ISS), abbreviated injury scale (AIS) score, maximum AIS score, and trauma and injury severity score probability of survival. We conducted multiple regression analysis to determine predictors of LHoS and LERS.

RESULTS

Within the study period, 82 victims met the inclusion and exclusion criteria and were included. Mean age was (46.0 ± 24.7) years. Overall mean LHoS was (16.8 ± 25.2) days, mean LERS was (10.6 ± 14.7) days, median ISS was 9 (interquartile range (IQR): 3-16), median maximum AIS was 3 (IQR: 1-4), and median trauma and injury severity score probability of survival was 98.0% (IQR: 95.5%-99.6%). Age, maximum AIS, ISS, and prevalence of surgery were significantly greater in long LHoS and LERS group compared with short LHoS and LERS group (p < 0.05). Performance of surgery independently explained LHoS (p = 0.0003) and ISS independently explained LERS (p = 0.0009).

CONCLUSION

Surgery was associated with long hospital stays and ISS was associated with long emergency room stays. To improve the quality life of the bicyclists, preventive measures for reducing injury severity or avoiding injuries needing operation are required.

Pharmacokinetics of duloxetine self-administered in overdose with quetiapine and other antipsychotic drugs in a Japanese patient admitted to hospital

Background

Combinations of antidepressant duloxetine (at doses of 40–60 mg/day) and other antipsychotics are frequently used in clinical treatment; however, several fatal and nonfatal cases of duloxetine overdose have been documented. We experienced a patient who had taken an overdose of duloxetine (780 mg) in combination with other drugs in a suicide attempt.

Case presentation

The patient was a 37-year-old man (body weight, 64 kg) with a history of gender identity disorder and depression. He intentionally took an overdose of duloxetine in combination with three other antipsychotic drugs (18 mg flunitrazepam, 850 mg quetiapine, and 1100 mg trazodone) and was emergently admitted to Kyoto Medical Center. The patient’s plasma concentration of duloxetine during ambulance transport was 57 ng/ml, and the level was still as high as 126 ng/mL at 32 h after administration. Duloxetine disappeared most slowly from plasma, in contrast to quetiapine, which was the fastest to clear among the four medicines determined in this patient. The observed concentrations of duloxetine in this overdose patient were generally within the 95% confidence intervals of the plasma concentration curves predicted using a physiologically based pharmacokinetic (PBPK) model.

Conclusion

Even if more than 1 h (the generally recommended period) has passed after administration of duloxetine in such overdose cases, gastric lavage and/or administration of activated charcoal may be effective in clinical practice up to 6 h because of the typically slow elimination behavior illustrated by the PBPK model. Pharmacokinetic profiles visualized using PBPK modeling can inform treatment decisions in cases of drug overdose for medicines such as duloxetine in emergency clinical practice.

Pharmacokinetics of anticoagulant edoxaban in overdose in a Japanese patient transported to hospital

Background

The anticoagulant edoxaban is used clinically at doses of 30–60 mg/day; however, we experienced a patient who had taken an overdose of edoxaban of 750 mg. We investigated the pharmacokinetics of edoxaban in this patient by using liquid chromatography–tandem spectrometry to estimate the follow-up period in emergency clinical practice with this medicine.

Case presentation

The patient was a 57-year-old woman (body weight, 69 kg) who had taken a single oral dose of 750 mg of edoxaban in a suicide attempt. She was emergently admitted to Kyoto Medical Center. The patient’s edoxaban plasma concentrations during ambulance transport (8 h after oral administration) were ~ 4900 ng/ml, and the concentration gradually decreased to ~ 10 ng/mL and to detectable but unmeasurable levels of ~ 1.0 ng/mL at 60 h and 100 h, respectively. The linear range of the relationship between the dose and plasma concentration was assumed to have been exceeded during the first 8 h; however, the measured elimination rate of edoxaban was similar to that visualized curves predicted by a simplified physiologically based pharmacokinetic model previously established.

Conclusion

Simplified physiologically based pharmacokinetic models for creating visualized curves have proven to be useful not only during drug discovery or chemical risk assessment but also in cases of medical poisoning. We used a physiologically based pharmacokinetic model previously established for edoxaban to predict the pharmacokinetics in the current case. It is hoped that the results of this study, which encompass drug monitoring data in the patient and visualized pharmacokinetic prediction, will serve as an index when setting the treatment and follow-up period in cases of drug overdose for medicines such as edoxaban in emergency clinical practice.

Cerebral oxygenation monitoring during resuscitation by emergency medical technicians: a prospective multicenter observational study

Aim

To assess the feasibility and predictive ability of regional cerebral oxygen saturation monitoring during cardiopulmonary resuscitation by emergency medical technicians.

Methods

This prospective observational study included 33 cardiac arrest patients who received cardiopulmonary resuscitation in a prehospital setting. Patients were connected to a near‐infrared spectrometer through two disposable probes immediately after entering the ambulance. The monitor, which showed regional cerebral oxygen saturation readings, was obscured by covering it with a sheet of paper. Regional cerebral oxygen saturation was measured continuously until hospital arrival. Outcome variables included the prehospital return of spontaneous circulation, survival to hospital admission, and survival at 90 days.

Results

For patients who survived >90 days after hospital admission (n = 2), the mean regional cerebral oxygen saturation values upon ambulance and hospital arrival were 24% and 60%, respectively; for patients who did not survive (n = 31), the mean regional cerebral oxygen saturation values were 15% and 17%, respectively. Regional cerebral oxygen saturation values increased to a greater extent between ambulance arrival and hospital arrival in patients who survived >90 days (median, 36%; interquartile range, 32–40%) than in those who did not survive (0; 0–6%; P = 0.07). Additionally, regional cerebral oxygen saturation values were not related to the prehospital return of spontaneous circulation or survival to hospital admission.

Conclusion

Regional cerebral oxygen saturation could be monitored during resuscitation by emergency medical technicians, and it can be used during physiological monitor‐guided cardiopulmonary resuscitation.

Transient severe distributive shock due to early dumping syndrome: a case report

Background

Early dumping syndrome characterized by palpitation, dizziness, cold sweat, feebleness, and abdominal symptoms, occurs within 30 minutes after meals in patients who have undergone gastrectomy. This case report describes the case of a patient who presented with severe distributive shock due to early dumping syndrome; he recovered within a few hours after massive fluid infusion and vasopressor administration.

Case presentation

Our patient was a 68-year-old Japanese man who underwent total gastrectomy for gastric cancer and was diagnosed as having late dumping syndrome. On admission, he developed severe shock and was treated with massive fluid administration. Based on the history of the present illness, past medical history, normal findings of blood chemistry test, transient course, and Sigtad score, which helps diagnose dumping syndrome, early dumping syndrome was considered the cause of severe distributive shock.

Conclusions

Early dumping syndrome can cause severe shock requiring massive fluid infusion and vasopressor administration. It should be considered a cause of severe distributive shock in patients who have undergone gastrectomy.

Treatment of Acute Myocardial Infarction with Cardiogenic Shock using Left Ventricular Assist Device

We have treated ten cardiogenic shock patients after acute myocardial infarction (AMI) with a left ventricular assist device (LVAD). These patients were later divided into three groups: the first group with ventricular septal perforation, the second with aorto-coronary bypass grafting (ACBG) before LVAD implantation and the third group without ACBG. LVAD maintained the systemic circulation in each group, and cardiac function recovered enough to remove LVAD in 70% of the total patients. Two of three patients in the first group were discharged from hospital. Two weaned cases in the second group died of multiple organ failure and one was discharged, and hemorrhagic necrosis was seen in the bypassed area of the myocardium. One patient of the third group could not be weaned from LVAD because of respiratory failure though his heart function began to recover. Another case in the third group underwent bypass grafting after removal of LVAD. However ACBG surgery should be done very carefully because a patient in shock is occasionally intolerant to major surgery. In all groups, the major cause of death was multiple organ failure which was probably caused by the prolonged low output condition prior to LVAD application. In the light of this experience, it appears that LVAD should be applied before irreversible damage occurs to major organs, including the heart itself. To ensure the timely application of LVAD, some way must be found to introduce systematic application of LVAD into the normal course of AMI treatment.

Tracheal injury detected immediately after median sternotomy by inexperienced surgeons: two case reports

Background

Although median sternotomy is standard during cardiac surgery, the procedure is associated with a risk of injury to mediastinal organs. Here, we discuss two cases of tracheal injury following median sternotomy during cardiac surgery.

Case presentation

Ventilation failure occurred in a 78-year-old Japanese man and a 71-year-old Japanese man after median sternotomy, and tracheal injury was identified. The sites of injury were directly repaired and covered with mediastinal fat tissue, following which ventilation was successful. The burn-like deposits observed at the site of tracheal injury and on the removed endotracheal tube support the notion that the injuries in our patients were caused by electrocautery prior to median sternotomy. In one case, short sternotracheal distance may have contributed to tracheal injury during post-sternal manipulation. In both cases, the relative inexperience of both surgeons also supports the suspected cause of injury.

Conclusions

Tracheal injury represents a potential complication following median sternotomy, especially when performed by inexperienced surgeons or in cases of short sternotracheal distance. Anesthesiologists should consider this rare yet potentially lethal complication.

Combined short- and long-axis ultrasound-guided central venous catheterization is superior to conventional techniques: A cross-over randomized controlled manikin trial

OBJECTIVES

Visualizing the needle tip using the short-axis (SA) ultrasound-guided central venous catheterization approach can be challenging. It has been suggested to start the process with the SA approach and then switch to the long-axis (LA); however, to our knowledge, this combination has not been evaluated. We compared the combined short- and long-axis (SLA) approach with the SA approach in a manikin study.

METHODS

We performed a prospective randomized controlled cross-over study in an urban emergency department and intensive care unit. Resident physicians in post-graduate years 1-2 performed a simulated ultrasound-guided internal jugular vein puncture using the SA and SLA approaches on manikins. Twenty resident physicians were randomly assigned to two equal groups: (1) one group performed punctures using the SA approach followed by SLA; and (2) the other performed the same procedures in the opposite order. We compared the success rate and procedure duration for the two approaches. Procedural success was defined as insertion of the guide-wire into the vein while visualizing the needle tip at the time of anterior wall puncture, without penetrating the posterior wall.

RESULTS

Six resident physicians (30%) performed both approaches successfully, while 12 (60%) performed the SLA approach, but not the SA, successfully. Those who performed the SA approach successfully also succeeded with the SLA approach. Two resident physicians (10%) failed to perform both approaches. The SLA approach had a significantly higher success rate than the SA approach (P < 0.001). The median (interquartile range) procedure duration was 59.5 [46.0-88.5] seconds and 45.0 [37.5-84.0] seconds for the SLA and SA approaches, respectively. The difference of the duration between the two procedures was 15.5 [0-28.5] seconds. There was no significant difference in duration between the two approaches (P = 0.12).

CONCLUSIONS

Using the SLA approach significantly improved the success rate of internal jugular vein puncture performed by novice physicians on a manikin model, without increasing procedural duration. Further clinical trials are warranted to confirm the procedure's utility in actual patients.

TRIAL REGISTRATION

UMIN Clinical Trials Registry UMIN000026199.

Repetitive postoperative extubation failure and cardiac arrest due to laryngomalacia after general anesthesia in an elderly patient: a case report

The authors report a case involving an elderly patient who experienced repetitive perioperative cardiac arrest caused by laryngomalacia. The patient underwent surgery under general anesthesia; however, 2 h after initial extubation, he experienced cardiopulmonary arrest. Return of spontaneous circulation was achieved by immediate resuscitation. Four hours later, a second extubation was performed without any neurological complications. However, 2 h later, he experienced cardiopulmonary arrest again. Immediately after the third extubation, 12 h after the second cardiopulmonary arrest, fiberoptic laryngoscopy revealed laryngomalacia. His respiratory condition stabilized after emergent tracheostomy. Laryngomalacia should be considered even in adult cases when signs of upper airway obstruction manifest after extubation.

Effect of Dexmedetomidine on Mortality and Ventilator-Free Days in Patients Requiring Mechanical Ventilation With Sepsis: A Randomized Clinical Trial

IMPORTANCE

Dexmedetomidine provides sedation for patients undergoing ventilation; however, its effects on mortality and ventilator-free days have not been well studied among patients with sepsis.

OBJECTIVES

To examine whether a sedation strategy with dexmedetomidine can improve clinical outcomes in patients with sepsis undergoing ventilation.

DESIGN, SETTING, AND PARTICIPANTS

Open-label, multicenter randomized clinical trial conducted at 8 intensive care units in Japan from February 2013 until January 2016 among 201 consecutive adult patients with sepsis requiring mechanical ventilation for at least 24 hours.

INTERVENTIONS

Patients were randomized to receive either sedation with dexmedetomidine (n = 100) or sedation without dexmedetomidine (control group; n = 101). Other agents used in both groups were fentanyl, propofol, and midazolam.

MAIN OUTCOMES AND MEASURES

The co-primary outcomes were mortality and ventilator-free days (over a 28-day duration). Sequential Organ Failure Assessment score (days 1, 2, 4, 6, 8), sedation control, occurrence of delirium and coma, intensive care unit stay duration, renal function, inflammation, and nutrition state were assessed as secondary outcomes.

RESULTS

Of the 203 screened patients, 201 were randomized. The mean age was 69 years (SD, 14 years); 63% were male. Mortality at 28 days was not significantly different in the dexmedetomidine group vs the control group (19 patients [22.8%] vs 28 patients [30.8%]; hazard ratio, 0.69; 95% CI, 0.38-1.22; P = .20). Ventilator-free days over 28 days were not significantly different between groups (dexmedetomidine group: median, 20 [interquartile range, 5-24] days; control group: median, 18 [interquartile range, 0.5-23] days; P = .20). The dexmedetomidine group had a significantly higher rate of well-controlled sedation during mechanical ventilation (range, 17%-58% vs 20%-39%; P = .01); other outcomes were not significantly different between groups. Adverse events occurred in 8 (8%) and 3 (3%) patients in the dexmedetomidine and control groups, respectively.

CONCLUSIONS AND RELEVANCE

Among patients requiring mechanical ventilation, the use of dexmedetomidine compared with no dexmedetomidine did not result in statistically significant improvement in mortality or ventilator-free days. However, the study may have been underpowered for mortality, and additional research may be needed to evaluate this further.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01760967.

Successful non-operative management of traumatic extrahepatic portal venous injury without intraperitoneal hemorrhage: a case report

Case

A 52‐year‐old woman was admitted to our hospital with hypotension after falling from the fifth floor of an apartment building. Contrast‐enhanced computed tomography showed liver injury with extravasation of contrast material from the hepatic artery, and extrahepatic portal venous injury with extravasation and pseudoaneurysm. Intra‐abdominal hemorrhage was not observed, and bleeding was confined to the retroperitoneal space. Hepatic arteriography showed extravasation, while portal venography showed pseudoaneurysm but no extravasation. After transarterial embolization, the patient's vital signs improved. Non‐operative management was selected for the portal venous injury.

Outcome

Computed tomography on the 58th hospital day revealed disappearance of the portal venous pseudoaneurysm. The patient was discharged on the 90th hospital day without any complications.

Conclusion

This case shows that non‐operative management can be selected for portal venous injury when there is no retroperitoneal injury and bleeding is confined to the retroperitoneal space.

Lymph node density predicts lung metastases in oral squamous cell carcinoma

The association between lymph node density and survival free of lung metastases in oral squamous cell carcinoma (SCC), has not been investigated so far to our knowledge. Lymph node density ≧ 0.07 has been reported by a multicentre international study to be a significant predictor of shorter survival in patients with oral SCC who have invaded nodes. We investigated whether a lymph node density of ≧ 0.07 correlates with shorter overall survival, survival free of distant metastases, and survival free of lung metastases, in patients with oral SCC and invaded lymph nodes. Thirty-five patients with histologically-confirmed invaded lymph nodes werestudied. Their density was calculated as the ratio of the number of invaded lymph nodes:total number of nodes. A density of ≧ 0.07 correlated significantly with shorter overall survival (p<0.02), survival free of distant metastases (p<0.01), and survival free of lung metastases (p<0.01) on log rank testing. On testing by Cox's proportional hazards model of multivariate survival analysis with adjustment for the pathological stage (pstage IV/pstage III), and invaded surgical margins or extracapsular spread, or both, we found that lymph node density ≧ 0.07 was associated with significantly shorter survival (p<0.02). We conclude that lymph node density predicts lung metastases in patients with oral SCC.

Acute lung inflammation and ventilator-induced lung injury caused by ATP via the P2Y receptors: an experimental study

BACKGROUND

Extracellular adenosine 5'-triphosphate (ATP) is an endogenous signaling molecule involved in multiple biological phenomena, including inflammation. The effects of extracellular ATP in the lung have not been fully clarified. This study examined 1) the biological roles of extracellular ATP in the pathogenesis of lung inflammation and 2) the possibility of involvement of extracellular ATP in mechanical ventilation-induced lung injury.

METHODS

The effects of intratracheal ATP on lung permeability, edema or lung inflammation were assessed by measurements of the lung wet-to-dry weight ratio and lung permeability index, immunohistochemistry and expression of key cytokines by real-time polymerase chain reaction. The ATP concentration in broncho-alveolar lavage (BAL) fluid from mice mechanically ventilated was measured by luciferin-luciferase assay. The suppressive effects of a P2 receptor antagonist on ventilator-induced lung inflammation were also examined.

RESULTS

ATP induced inflammatory reactions in the lung mainly via the ATP-P2Y receptor system. These reactions were alleviated by the co-administration of a specific P2 receptor antagonist. Mechanical ventilation with a large tidal volume caused lung inflammation and increased the ATP concentration in BAL fluid. P2 receptor antagonism partially mitigated the inflammatory effects of large tidal volume ventilation.

CONCLUSION

Our observations suggest that the ATP-P2Y receptor system is partially involved in the pathogenesis of ventilator-induced lung injury.

[Case of cerebral salt wasting syndrome with difficulty in controling excessive urine volume]

Symptoms of hyponatremia and diuresis due to cerebral salt wasting syndrome (CSWS) are often observed after aneurysmal subarachnoid hemorrhage (SAH). Inadequately treated CSWS is known to work as a trigger of symptomatic vasospasm in SAH patients. Therefore, it is indispensable to detect and treat CSWS as early as possible in ICU. A 36-year-old man with SAH was admitted to our ICU. His urine volume increased excessively 3 days after ICU admission, and it reached a peak (39,250 ml x day(-1)) on the 6th day in ICU. Since infusion volume was controlled with regard to daily urinary output, hyponatremia was not noticeable and excessive urine volume stood out conspicuously. Though vasopressin and desmopressin were administered, the symptoms of natriuresis and hyponatremia were aggravated, associated with hyper secretion of natriuretic peptides (ANP 160 pg x dl(-1), BNP 172 pg x dl(-1)). Recent studies revealed that hyponatremia and hypovolemia following SAH might be caused by exaggerated secretion of natriuretic peptides. Experimental studies showed that the administration of vasopressin and desmopressin cause excessive secretion of natriuretic peptides under the circumstance of volume expansion in rats. We infer that the administration of vasopressin and desmopressin to our patient deterionated natriuresis in CSWS as in the previous experimental findings.

[Evaluation of postoperative pain relief after video-assisted thoracoscopic surgery (VATS) for spontaneous pneumothorax]

BACKGROUND

We have investigated correlation between postoperative pain and chest tube insertion after video-assisted thoracoscopic surgery (VATS) for patients with spontaneous pneumothorax, and have evaluated preemptive analgesia by intercostal nerve block (ICB) using bupivacaine.

METHODS

Thirty patients received VATS for spontaneous hemi-pneumothorax. There were two groups of the patients; Group CT received chest tube before the operation, and the Group NCT received no chest tube. Both groups received general anesthesia combined with ICB by 0.25% bupivacaine at the surgical region before operation. Postoperative pain was assessed using visual analogue scale (VAS scale: 0-10) and the need for additional supplemental analgesics before the operation, and at 6 and 24 hours after the operation, and at 3, 7, 14, and 30 days after the operation.

RESULTS

Visual analogue scale in Group NCT before the operation, and at 24 hours, 3, 7, 14, and 30 days after the operation was significantly lower than that of Group CT. Analgesic requirements were significantly lower in the Group NCT than in the Group CT.

CONCLUSIONS

We should avoid the insertion of a chest tube before the operation as much as possible. Furthermore early operation and intercostal nerve blockade before the operation were useful to prevent postoperative pain and its shift to chronic post thoracostomy pain.

[Mechanical supports for stunned myocardium after esophagectomy]

Coronary vasospasm can cause a wide spectrum of clinical syndromes ranging from transient myocardial ischemia to irreversible infarction. A 72-year-old male patient had intense vasospasms intraoperatively, which led to stunned myocardium. Though MB fraction of creatine kinase after the spasms was almost within normal limits, postoperative transcutaneous echocardiogram showed diffuse hypokinesis of heart wall motion. He developed low output syndrome, acute respiratory distress syndrome and acute renal failure. He was treated with mechanical supports (intra-aortic balloon pumping, high frequency oscillatory ventilation, and continuous hemodiafiltration), in addition to intravenous administration of cathecolamines, on the first postoperative day. It took 6 days to wean the patient from these mechanical supports and catecholamine infusion. This case suggests stunned myocardium after coronary vasospasm, despite the rapid disappearing ST elevation, and of importance of mechanical supports for the circulatory failure.

Serial assessment of left and right ventricular filling in patients with congestive heart failure

Serial changes in the diastolic filling of both ventricles were studied using Doppler echocardiography in 19 patients with congestive heart failure from the acute to the convalescent stage. During the acute stage, left ventricular early filling velocity (E) was high (88 +/- 17 cm/s) and atrial filling velocity (A) was low (44 +/- 23 cm/s), whereas the right ventricular E was depressed (17 +/- 8 cm/s) and A was enhanced (40 +/- 9 cm/s). As the condition improved, left ventricular E decreased (43 +/- 11 cm/s, p < 0.01) and A increased (59 +/- 24 cm/s, p < 0.01) along with a decrease in the left ventricular and atrial dimensions. In contrast to the changes in left ventricular filling, right ventricular E increased (31 +/- 10 cm/s, p < 0.01) and A decreased (32 +/- 5 cm/s, p < 0.05). There are opposite directional changes in left and right ventricular filling with clinical improvement from the acute to the convalescent stage of congestive heart failure, which suggest that the changes are related to improvement of the hemodynamic conditions of both ventricles. The changes in the right ventricular filling pattern was likely to be related to changes in right ventricular afterload, ventricular interaction and external constraint rather than a change in right ventricular filling pressure.

[On line display of the reconstructed pressure waves of the radial artery from the monitored output pressure waves at the same site]

The input-output relationship of transducer and catheter system is described by linear, second-order differential equation with three coefficients: inductance (L), resistance (R), and capacitance (C). Once the natural frequency (fo) and the damping ratio (beta) of the monitoring system have been measured, three coefficients of the differential equation are uniquely obtained. We measured the frequency response of the monitoring system, which we usually use in our hospital, to obtain fo and beta, and reconstructed the original input arterial pressure wave from output signal on the display using the simple time-domain approach. The analysis of this linear, second-order differential equation, is applicable in on-line bedside monitoring, because the calculation of this equation is simpler than that using Fourier's translation. The pressure waves of the radial artery both monitored (output) and restored (input) were depicted on the same display at the same time. We can evaluate the changes in systemic circulation from the changes in the wave shapes of arterial blood pressure.

[Effect of oxygen inhalation on myocardial opacification using levovist: an animal experimental study]

OBJECTIVES

Levovist can opacify the myocardium via venous injection, and is widely used in the clinical field. However, left ventricular opacification deteriorates during oxygen inhalation using Albunex, one of the first generation of contrast agents. This study examines the effect of blood oxygen pressure on the myocardial opacification by Levovist.

METHODS

Myocardial contrast echocardiography (Toshiba Power Vision 6000) was performed using second harmonic imaging, intermittent exposure of ultrasound (every 4 cardiac beats) and acoustic power of 1.4 mechanical index. The video intensity of the ventricular septum after venous injection of Levovist (0.5 ml of 300 mg/ml) was measured under various respiratory conditions by manipulating the respirator and oxygen inhalation. Arterial blood gas was measured and correlated with the myocardial video intensity.

RESULTS

The video intensity of myocardial opacification was lower with higher oxygen pressure in the arterial blood. Visual recognition of myocardial opacification was only 14% under high oxygen pressure over 200 mmHg. Microbubbles of Levovist form from normal air, and are easily affected by the gas concentration of the surrounding blood.

CONCLUSIONS

Myocardial opacification using Levovist is deteriorated under high oxygen pressure at examination.

[Optimal setting of focus points for myocardial contrast echocardiography with intravenous Optison (FS-69): an experimental study]

OBJECTIVES

Myocardial contrast echocardiography is useful to assess myocardil perfusion, but myocardial opacification is affected by the setup of the ultrasonic equipment. The optimal setting of focus points for adequate opacification of the myocardium was examined in myocardial contrast echocardiography.

METHODS

Myocardial contrast echocardiography was performed in six dogs using triggered second harmonic technology following intravenous administration of Optison(FS-69). The short-axis view was recorded and baseline subtracted video intensity(peak intensity: PI) was calculated at three regions of the left ventricular wall, the anterior, septum, and posterior walls, to evaluate myocardial opacification. The focus point was set at near(2 cm), middle(4 cm) and far(6 cm)points. The myocardial opacification was evaluated at each focus setting. The effect of the acoustic power was also examined by changing the mechanical index to 1.6, 1.2 or 0.8.

RESULTS

Myocardial opacification was recognized at all focus points, and segments near the focus points had high PI. However, the PI of the posterior wall was lowest at near focus, whereas the PI of the anterior wall was lowest at far focus. The difference of PI between the anterior and posterior walls was significant (p < 0.05, p < 0.01, respectively) at either focus point. Adequate myocardial opacification of all segments was observed when the focus was set at the middle point. The PI of the whole left ventricle increased relative to mechanical index.

CONCLUSIONS

Setting up of focus points at the middle of the left ventricle provides more homogeneous myocardial opacification of the whole left ventricle in myocardial contrast echocardiography, and high acoustic power possibly improves myocardial opacification. Inadequate setting of focus points leads to inadequate estimation of myocardial perfusion by myocardial contrast echocardiography.

[Usefulness of intravenous myocardial contrast echocardiography in rats]

OBJECTIVES

Few intravenous myocardial contrast echocardiography trials have evaluated myocardial perfusion in small animals. The feasibility of using intravenous myocardial contrast echocardiography to assess the ischemic area in rats was investigated.

METHODS

Fourteen open chest Wister male rats were examined. Intravenous myocardial contrast echocardiography was performed by fundamental and intermittent mode using a high frequency (5-12 MHz) transducer (SONOS 5500) with injection of NC100100 (20% dilution) into the femoral vein. The mechanical index was set to 1.6. Baseline-subtracted video intensity (256 level) was measured in the anterior, posterior, septal and lateral walls of the left ventricle. The left anterior descending artery was ligated in 16 rats. The area at risk was evaluated by myocardial contrast echocardiography and compared to the area of defect by Evans Blue staining.

RESULTS

All wall segments were clearly opacified (anterior 63.8 +/- 24.7, posterior 27.0 +/- 11.0, septal 44.5 +/- 11.6, lateral 52.3 +/- 19.1), although the baseline-subtracted video intensity of the posterior wall was low. The area at risk was clearly observed, and there was a good correlation with the nonperfused area by Evans Blue staining (y = 1.13x-3.54, r = 0.98).

CONCLUSIONS

Intravenous myocardial contrast echocardiography can detect the perfusion defect even in rats using a high frequency transducer and suitable setup of equipment.

Myocardial ischemia activates the JAK-STAT pathway through angiotensin II signaling in in vivo myocardium of rats

There have been many studies concerning the hemodynamics and physiological mechanisms in ischemic heart disease, little is known about molecular mechanisms during myocardial ischemia in in vivo study. As the signal transduction pathway responsible for myocardial hypertrophy and apoptosis, janus kinase (JAK) and signal transducers and activators of transcription (STAT) are suggested to play an important role. However, whether in vivo activation of JAK-STAT pathway occurs during myocardial ischemia is still unknown. The purpose of this study was to determine whether myocardial JAK or STAT is activated in ischemic heart, and to evaluate the angiotensin blockade on the pathway. Myocardial infarction was produced by ligation of the coronary artery in Wistar rats. After myocardial ischemia, we analysed both activated levels and total amounts of JAK1, JAK2, STAT1 and STAT3 by Western blot analyses at 0, 5, 15, 30, 60, 120 and 240 min. Compared with JAK activities at 0 min, JAK1 activities were significantly increased at 60 and 120 min (3.0- and 3.7-fold, respectively, P<0.01). JAK2 and STAT1 activities of ischemic myocardium were unchanged through the time course. STAT3 activities were increased at 5 min (3.3-fold, P<0.01) and markedly enhanced at 30, 60 and 120 min (4.6-, 7.7- and 8.7-fold, respectively, P<0.01). Pretreatment with imidapril (ACE inhibitor) and candesartan cilexitil (AT1 receptor antagonist) significantly prevented the increase in the phosphorylation of JAK1 at 120 min and STAT3 at 30 and 120 min. Sis-inducing factor (SIF) DNA complex was supershifted by specific anti-STAT3 antibody, indicating that increased SIF complex at least contained activated STAT3 proteins in ischemic myocardium. Imidapril and candesartan cilexitil inhibited the activation of SIF DNA binding at 1 day after coronary ligation. In conclusion, we showed that JAK1 and STAT3 were activated by ischemia from the basal activities in in vivo rat myocardial ischemia model. Imidapril and candesartan cilexitil prevented the increase in phosphorylated JAK1 and STAT3, thereby suggesting that angiotensin II, especially angiotensin II type I receptor, partially mediates activation of myocardial JAK-STAT pathway in acute myocardial ischemia.

Effects of sildenafil citrate (Viagra) combined with nitrate on the heart

BACKGROUND

Sildenafil citrate (Viagra) is indicated for the treatment of erectile dysfunction. Large and sudden decreases in systemic blood pressure were reported in a substantial number of patients taking sildenafil citrate combined with nitroglycerin. We studied the effect of sildenafil citrate on the relationship between changes in systemic blood pressure and coronary blood flow.

METHODS AND RESULTS

Healthy male beagles were used to assess systemic blood pressure, pulmonary arterial pressure, and flow in the left circumflex artery (in which a critical stenosis was established) and left anterior descending coronary artery. After measurement of the hemodynamic variables, 2 mg/kg sildenafil citrate was administered via a nasogastric tube. Hemodynamic changes were monitored for 1 hour. Subsequently, the acute effect of nitrate combined with sildenafil citrate was studied by the bolus injection of 0.2 mg isosorbide dinitrate before and after sildenafil citrate. Systemic blood and pulmonary arterial pressures and circumflex flow did not change during this study; however, left anterior descending coronary arterial flow increased from 16.0+/-5.8 to 24.6+/-8.7 mL/min 1 hour after administration of sildenafil citrate. The prolongation of systemic blood pressure decrease and the circumflex flow decrement induced by isosorbide dinitrate after sildenafil citrate were significantly larger and longer than those before sildenafil citrate.

CONCLUSIONS

Sildenafil citrate had the effect of vasodilation in a normal coronary artery; however, a combined effect with nitrate resulted in large and protracted decreases in systemic blood pressure and coronary blood flow in vessels with critical stenosis.

Assessment of flow mismatch with pharmacologic stress test on myocardial contrast echocardiography in a model of critical stenosis: adenosine triphosphate and dipyridamole

Although adenosine triphosphate (ATP) is a favorable vasodilator because of its short-acting duration, the agent's effectiveness in facilitating the diagnosis of myocardial ischemia with myocardial contrast echocardiography (MCE) is not fully understood. The goal of this study was to examine the efficacy of intravenous ATP administration (0.15 to 0.30 mg/kg/min for 5 minutes) in diagnosing the flow mismatch with MCE. To achieve this, a critical stenosis was produced in the left circumflex artery in 10 anesthetized dogs. The peak intensity ratio of risk area to control area was reduced by ATP from 0.51 +/- 0.19 to 0.31 +/- 0.12 (P <.05). Systolic wall thickening of the risk area did not change significantly (32.8% +/- 9.8% to 27.5% +/- 12.8%). These changes did not differ from those obtained after dipyridamole. We conclude that MCE with intravenous ATP administration is as useful as the dipyridamole method for diagnosing critical coronary stenosis.

Characteristic cardiovascular manifestation in homozygous and heterozygous familial hypercholesterolemia

BACKGROUND

The aortic valve dysfunction of patients with homozygous familial hypercholesterolemia (FH) suggests that hypercholesterolemia affects not only coronary arteries but also the aortic valve. We studied the aortic root of patients with homozygous FH and those of patients with heterozygous FH to characterize the premature atherosclerotic lesions by using histopathologic specimens.

METHODS AND RESULTS

The aortic roots of 10 patients with homozygous FH, age 9 to 58 years, were studied by cardiac catheterization with several angiographies. The aortic roots of 39 patients with heterozygous FH under age 60 years were also examined for aortic and mitral valvular functions by color Doppler echocardiography, and 30 normocholesterolemic patients with coronary artery disease were examined as control subjects. In addition, in 22 patients with FH and 20 control subjects, the internal diameter of the aortic annulus and the aortic ridge in cardiac cycles were measured. Of the 10 homozygotes with FH, 8 patients had aortic regurgitation demonstrated by aortography; 3 of them showed significant transvalvular pressure gradients. Stenotic changes of coronary ostia were observed in 8 of the 10 homozygotes with moderate coronary atherosclerosis. Of the 39 heterozygotes with FH, 10 patients had aortic regurgitation shown by Doppler echocardiography, as did only 1 of the 30 control subjects (P <.05). The average diameter and distensibility of the ascending aorta were significantly reduced in the heterozygotes compared with the control subjects. The surgically resected cusp specimens of aortic valves obtained from 1 homozygous and 1 heterozygous patient showed significant thickening of the cusp with foam cell infiltration.

CONCLUSIONS

Premature atherosclerosis in FH had a characteristic distribution, affecting the aortic root dominantly. The involvement of the aortic valve indicating "hypercholesterolemic valvulopathy" was a peculiar feature of FH, especially its homozygous form, but was reminiscent of ubiquitous processes caused by hypercholesterolemia.

Preparation and characterization of echogenic liposome as an ultrasound contrast agent: size-dependency and stabilizing effect of cholesterol on the echogenicity of gas-entrapping liposome

The liposome entrapping CO2 gas inside the vesicle, which is called the echogenic liposome, has been made and characterized in vitro as an ultrasound contrast agent. The small unilamellar vesicle (SUV), large unilamellar vesicle (LUV) and multilamellar vesicle (MLV) as echogenic liposomes were compared in their echogenic efficiency and stability, and the effect of size and acoustic property was tested. The acoustic reflectivity increased with the increase in size of the vesicle, largest for the gas filled MLV among the three liposome suspensions. The acoustic reflectivity obtained with the echogenic MLV was larger than that of the gas bubbles enclosed within a surfactant mixture. A half-lifetime of 39 min was observed for the MLV prepared from egg-yolk phosphatidylcholine liposomes. The duration of reflectivity was prolonged drastically to a half-lifetime of 866 min by incorporating cholesterol into the MLV, although the echogenicity was decreased by such incorporation. The stabilizing effect of cholesterol for the ordinary liposomal membrane was thus ascertained in the present case of the gas-entrapping liposome. Our findings encourage the future development of improved gas-entrapping liposomes for the clinical trials of ultrasound contrast agents.

[Levovist]

SH/TA-508 (Levovist) is agglomerates of microparticles consisting of galactose (99.9%) and palmitic acid (0.1%), and the active entity is the microbubbles stabilized by palmitic acid which covers the bubbles. SH/TA-508 micro-bubbles are stable under high-pressure condition and they circulate the whole body for several minutes along with blood flow after the intravenous injection. The left sided cardiac cavities and arteries are clearly opacified by using this contrast agent and the Doppler signals from the mitral, aortic and pulmonic vein are also enhanced significantly. Also microcirculating flow image of the liver, kidney and other organs are well enhanced in the clinical studies. SH/TA-508 improves the capability of ultrasound diagnosis.

Extension of hemorrhage after reperfusion of occluded coronary artery: contrast echocardiographic assessment in dogs

OBJECTIVES

The aim of this study was to elucidate the progression of intramural hemorrhage complicated by reperfusion with the use of myocardial contrast echocardiography.

BACKGROUND

Although hemorrhagic infarction is known to occur in ischemia followed by reperfusion, its onset and sequence have not been well characterized.

METHODS

In 20 anesthetized dogs, 3-h occlusion of the left circumflex-coronary artery was followed by reperfusion. The area at risk during coronary occlusion was approximately 25%. Myocardial contrast echocardiogram was examined, and the time-intensity curves for both ischemic and nonischemic areas were obtained at baseline, at 3 min after reperfusion and then at 15-min intervals until 90 min after reperfusion. The wall thickness of both areas was also measured.

RESULTS

Gross hemorrhage in the reperfused areas was observed in five dogs (Group H) but not in seven dogs (Group NH). All wall segments were opacified at 3 min after reperfusion in both groups. However, the contrast defect spread significantly with time after reperfusion in Group H but not in Group NH (18.7 +/- 3.4% and 3.3 +/- 1.8%, respectively, at 90 min after reperfusion p < 0.005). The wall of the risk area at 90 min after reperfusion had thickened to 1.3 times baseline thickness in Group H but was unchanged in Group NH. The other eight dogs were excluded from study because of fatal arrhythmias or the existence of collateral circulation during coronary occlusion.

CONCLUSIONS

Both progression of the contrast defect area on myocardial contrast echocardiography and a gradual thickening of the wall with reperfusion are characteristic of hemorrhagic infarction.

Relationship between progressive microvascular damage and intramyocardial hemorrhage in patients with reperfused anterior myocardial infarction: myocardial contrast echocardiographic study

BACKGROUND

Recent studies indicated that ischemic microvascular damage may be reversible or progressive after coronary reflow. Intramyocardial hemorrhage is a phenomenon that reflects severe microvascular injury. We examined the relationship between temporal changes in microvascular perfusion patterns detected by myocardial contrast echocardiography (MCE) and intramyocardial hemorrhage detected by magnetic resonance imaging (MRI) in patients with acute myocardial infarction (AMI).

METHODS AND RESULTS

The study population consisted of 24 patients with anterior AMI. All patients underwent MCE shortly after reflow and in the chronic stage (a mean of 31 days after reflow). Wall motion score (WMS) was determined as the sum of 16 segmental scores (dyskinetic/akinetic=3 to normal=0) at days 1 and 31. Gradient-echo acquisition and gadolinium-DTPA-enhanced spin-echo MRI were performed within 10 days after reflow. In MCE shortly after reflow, 16 patients (67%) showed contrast enhancement and the other 8 patients (33%) showed a sizable contrast defect. In the chronic stage, a persistent contrast defect was observed in 7 of 8 patients with a contrast defect shortly after reflow. Consistent contrast enhancement was observed in 12 of 16 patients (75%) with contrast enhancement shortly after reflow, indicating that a contrast defect newly appeared in 4 patients (25%). Intramyocardial hemorrhage was detected in 9 patients (38%): 5 of 7 patients with a persistent contrast defect and in all 4 patients with a new appearance of a contrast defect during the chronic stage. The patients without hemorrhage showed a significant improvement in WMS compared with patients with hemorrhage at day 31 (5+/-5 versus 19+/-6, P<.0005).

CONCLUSIONS

These results suggest that irreversible microvascular damage to the ischemic myocardium may cause intramyocardial hemorrhage after reflow, associated with impaired recovery of left ventricular function. Contrast enhancement within the risk area shortly after reflow does not necessarily indicate long-term microvascular salvage.

Functional myocardial perfusion abnormality induced by left ventricular asynchronous contraction: experimental study using myocardial contrast echocardiography

OBJECTIVES

The aim of this study was to clarify how myocardial perfusion is impaired by asynchronous contraction.

BACKGROUND

False septal hypoperfusion is noted in some patients with left bundle branch block.

METHODS

Eight dogs were examined with epicardial pacing at the left ventricular posterior wall, the right ventricular anterior wall and, as a control, the right atrial appendage. The pacing rate was 80, 110 and 150 beats/min (bpm). Myocardial perfusion was assessed by contrast echocardiography.

RESULTS

Left ventricular pacing at 80 and 110 bpm did not change systolic wall thickening or contrast intensity at the pacing site, although an early excitation notch was noted at the pacing site. However, at 150 bpm, systolic thickening was impaired (23.3 +/- 4.2% vs. 37.0 +/- 2.6% during atrial pacing, p < 0.05), and the peak intensity ratio of the pacing site to the ventricular septum was significantly decreased (24.1 +/- 5.7% vs. 37.0 +/- 2.8% at a pacing rate of 80 bpm, p < 0.01). The peak intensity ratio correlated with systolic wall thickening at the pacing site (y = 0.413 x -0.028, r = 0.81, p < 0.0001). However, right ventricular pacing did not change either systolic thickening or the peak intensity ratio at any pacing rate, although an early excitation notch was noted on the ventricular septum.

CONCLUSIONS

Wall motion abnormalities after early excitation vary depending on the pacing mode. When tachycardia induces regional wall motion abnormalities, the ventricular wall of the pacing site is functionally hypoperfused.

Prolonged myocardial contrast echocardiography via peripheral venous administration of QW3600 injection (EchoGen): its efficacy and side effects

We examined the efficacy and side effects of a newly developed contrast agent for intravenous myocardial contrast echocardiography, QW3600 Injection (EchoGen; Sonus Pharmaceuticals, Bothell, Wash.). Doses of 0.1, 0.2, 0.5, and 0.8 ml/kg of this agent were administered intravenously to 8 open-chested dogs. The left ventricular (LV) myocardium was uniformly well opacified for the 0.5 and 0.8 ml/kg doses, for which the peak intensity was an average of 40 gray levels above the baseline intensity. The myocardial opacification persisted even after the contrast echo intensity in the LV cavity had decreased. After ligation of the coronary artery, the area at risk was clearly delineated by the same doses. The agent emulsion and dissolved bubbles were examined microscopically in vitro and in vivo to elucidate the mechanism of prolonged opacification. A microscopic investigation of the mesenteric vessels of a rat indicated that bubbles had formed, growing as large as 30 to 50 microm [corrected] in diameter. The hemodynamic parameters did not change at low doses (0.1 and 0.2 ml/kg), but the systemic pressure fell and the arterial blood oxygen saturation decreased at high doses (0.5 and 0.8 ml/kg). EchoGen provides prolonged contrast for myocardial contrast echocardiography via peripheral venous administration, although the hemodynamic parameters deteriorate at high doses.

Identification of pseudonormal transmitral flow pattern using color Doppler echocardiography

The jet size of flow in color Doppler is dependent on both jet momentum and the compliance of the receiving chamber. Thus, the jet size of left ventricular (LV) late filling standardized by its jet momentum should reflect LV compliance. We investigated the feasibility of using color Doppler echocardiography to differentiate a pseudonormal from a normal transmitral flow pattern. We divided 37 patients with ischemic heart diseases who demonstrated a "normal" transmitral flow pattern into 2 groups according to their LV end diastolic pressure (LVEDP): a pseudonormalization group (LVEDP > or = 18 mmHg, 16 patients), and a normal group (LVEDP < 18 mmHg, 21 patients). We measured the maximum color Doppler jet length (L) and the peak velocity of transmitral flow during atrial contraction (Av). Filling volume (Q) was measured as the increase in LV volume during atrial contraction. A simplified jet momentum index (M) was obtained from Av x Q, and L/M was considered to reflect LV compliance. L/M was significantly lower in the pseudonormalization group that in the normal group (1.55 +/- 0.46 x 10(-3) vs 2.72 +/- 0.59 x 10(-3) p < 0.01). On the other hand, conventional Doppler variables such as isovolumic relaxation time and the deceleration time of early diastolic filling were not sufficient for discriminating between the 2 groups. In conclusion, color Doppler echocardiogram during atrial contraction was useful for differentiating a pseudonormal from a normal transmitral flow pattern.

[Prediction of ineffective outcome of surgical treatment for constrictive pericarditis]

The preoperative factors predicting the outcome of surgical treatment for constrictive pericarditis were investigated in 22 patients with constrictive pericarditis who underwent pericardiectomy. The NYHA functional class was improved in nine patients after surgery (improved group), but not in the other 13 patients (unimproved group). Preoperative right and left heart catheterization data and echocardiograms were compared between these two groups. Right atrial pressure (RAP) and pulmonary capillary wedge pressure (PCWP) were significantly higher in the unimproved group. The left atrial diameter (LAD) measured by echocardiography was significantly greater in the unimproved group. These results indicate that pericardiectomy will cause a worsened immediate outcome in patients with severe pericardial constriction. LAD was the most useful parameter in predicting the ineffectiveness of the pericardiectomy. If the borderline value of LAD is taken as 40 mm, the sensitivity and specificity predicting ineffective surgery were 92% and 89%, respectively. RAP and PCWP could not separate the two groups satisfactorily. Pericardiectomy should be performed before the pericardial constriction progresses, and before LAD reaches 40 mm.

[Feasibility of the left ventricular volume measurement by acoustic quantification method: comparison with ultrafast computed tomography]

Acoustic quantification (AQ: the real-time automated boundary detection system) allows instantaneous measurement of cardiac chamber volumes. The feasibility of this method was evaluated by comparing the left ventricular (LV) volumes obtained with AQ to those derived from ultrafast computed tomography (UFCT), which enables accurate measurements of LV volumes even in the presence of LV asynergy, in 23 patients (8 with ischemic heart disease, 5 with cardiomyopathy, 3 with valvular heart disease). Both LV end-diastolic and end-systolic volumes obtained with the AQ method were in good agreement with those obtained with UFCT (y = 1.04 x - 16.9, r = 0.95; y = 0.87x + 15.7, r = 0.91; respectively). AQ was reliable even in the presence of LV asynergy. Interobserver variability for the AQ measurement was 10.2%. AQ provides a new, clinically useful method for real-time accurate estimation of the left ventricular volume.

[Diagnosis of coronary artery dehiscence and pseudoaneurysm after modified Bentall operation by Doppler color flow imaging: a case report]

This 48-year-old man presented with anterior chest and back pain in 1981. He was treated with replacement of the ascending aorta and aortic valve under a diagnosis of dissection of the ascending aorta with severe aortic regurgitation. He underwent modified Bentall reoperation for the dilation of the aortic root in 1991. Postoperative two-dimensional echocardiography was performed because of sustained atrial flutter. An echo-free space was detected between the aorta graft and aorta wrapping on the short-axis view. Doppler color flow imaging revealed blood flow from the left coronary artery graft into the echo-free space. This leakage was suspected to be the cause of the echo-free space. Transesophageal echocardiography was performed to conform this hypothesis, which revealed blood flow from the left coronary artery graft into the echo-free space in systole and flow into the left coronary artery graft from the echo-free space in diastole.