The Guardian: an implantable system for chronic ambulatory monitoring of acute myocardial infarction

The AngelMed Guardian is an implantable medical device that records cardiac data and detects ischemic events using a standard pacemaker intracardiac lead positioned in the right ventricular apex. The Guardian has been implanted in 55 people in the United States and Brazil and is currently undergoing a Food and Drug Administration phase 2 pivotal trial in the United States. The Guardian detects acute ischemic events by analyzing ST-segment shifts. The ST-segment shifts are calculated as the difference between the ST deviation of a current 10-second electrogram window and a baseline ST deviation value. If the ST-segment shift is greater than a heart rate–dependent programmable threshold, then the device generates an emergency alert signal. Results thus far have demonstrated that (i) the intracardiac electrogram is relatively noise-free and (ii) the ST-shift technique used by the Guardian is effective for detecting acute ischemic events.     

Multiple intracranial aneurysms in a patient with Seckel syndrome

A 17-year-old girl affected by Seckel syndrome and multiple intracranial aneurysms is reported. Cerebral hemorrhage was the reason for the diagnostic work-up. The aneurysms were surgically treated. The main features of the syndrome, technical problems encountered during surgery and the prognosis of this condition are discussed. Received: 23 April 1997     

The association between socioeconomic development at the town level and the distribution of dental caries in Brazilian children.

OBJECTIVE: To investigate the association between dental caries among children in the state of S?o Paulo, Brazil, and town-level indices of socioeconomic development. METHODS: We examined 15 385 oral-examination records from children aged 5 or 6 years old from 129 towns and cities in the state of S?o Paulo. We studied two outcomes: (1) the mean number of decayed, missing, and filled deciduous teeth (dmft index) and (2) the care index, which is the proportion of decayed teeth that have already been filled. The explanatory variables were the child development index, human development index, illiteracy rate among subjects older than 20 years, household income, Gini coefficient, insufficient income, fluoridated water supply, number of dentists per 10 000 inhabitants, number of dentists in the public service per 10 000 inhabitants, and number of weekly hours of dentist work in the public service per 10 000 inhabitants. Multiple linear regression models were fitted to the two outcome variables (dmft index and care index). RESULTS: The multiple linear regression analysis showed that a higher dmft index was associated with a low child development index, a high illiteracy rate, and an unfluoridated water supply. The child development index was significantly associated with the care index, and the number of dentists in the public service per 10 000 inhabitants showed borderline statistical significance. CONCLUSIONS: Our results indicate that town-level indices of socioeconomic status are significantly correlated with caries indices. Our results also emphasize the beneficial effect that fluoridating water has on reducing the prevalence of dental caries and the fact that strategies for treating and preventing oral diseases should be emphasized within the context of overall health promotion for children.     

Assessment of cardiovascular regulation after burns by nonlinear analysis of the electrocardiogram

Critical illness and hypovolemia are associated with loss of complexity of the R-to-R interval (RRI) of the electrocardiogram, whereas recovery is characterized by restoration thereof. Our goal was to investigate the dynamics of RRI complexity in burn patients. We hypothesized that the postburn period is associated with a state of low RRI complexity, and that successful resuscitation restores it. Electrocardiogram was acquired from 13 patients (age 55 +/- 5 years, total body surface area burned 36 +/- 6%, 11 +/- 5% full thickness) at 8, 12, 24, and 36 hours during postburn resuscitation. RRI complexity was quantified by approximate entropy (ApEn) and sample entropy (SampEn) that measure RRI signal irregularity, as well as by symbol distribution entropy and bit-per-word entropy that assess symbol sequences within the RRI signal. Data (in arbitrary units) are means +/- SEM. All patients survived resuscitation. Changes in heart rate and blood pressure were not significant. ApEn at 8 hours was abnormally low at 0.89 +/- 0.06. ApEn progressively increased after burn to 1.22 +/- 0.04 at 36 hours. SampEn showed similar significant changes. Symbol distribution entropy and bit-per-word entropy increased with resuscitation from 3.63 +/- 0.22 and 0.61 +/- 0.04 respectively at 8 hours postburn to 4.25 +/- 0.11 and 0.71 +/- 0.02 at 24 hours postburn. RRI complexity was abnormally low during the early postburn period, possibly reflecting physiologic deterioration. Resuscitation was associated with a progressive improvement in complexity as measured by ApEn and SampEn and complementary changes in other measures. Assessment of complexity may provide new insight into the cardiovascular response to burns.     

Acquired methemoglobinemia after hydroxocobalamin administration in a patient with burns and inhalation injury

Context: Hydroxocobalamin is an effective cyanide antidote. While erythema, hypertension, and chromaturia are recognized side effects, methemoglobinemia has not been reported. Methemoglobin levels are most accurately measured by co-oximetry. We describe an extensively burned patient who developed methemoglobinemia within an hour of hydroxocobalamin administration.

Case details: A 47-year old man without genetic deficiencies or abnormal hemoglobin variants presented with 61% body surface area thermal burns and grade 1 inhalation injury sustained during a tugboat engine explosion. On admission, lactate was 9.24?mmol/L, methemoglobin 1%, and carboxyhemoglobin 0.2% by blood gas analysis with co-oximetry. Despite large-volume resuscitation, lactate remained elevated (7–8?mmol/L). Intravenous hydroxocobalamin (5?g) was administered at postburn hour 19 for possible cyanide toxicity. Immediately thereafter, he became hypertensive with reflex bradycardia. Lactate decreased to 5.51?mmol/L, methemoglobin rose to 4.10%, and oxygen saturation by pulse oximetry decreased to 74–80% (despite arterial oxygen saturation of 95% by cooximetry). Methemoglobin concentration peaked at 13.40% at postburn hour 33. Methylene blue was not administered.

Conclusions: Methemoglobinemia in our patient was temporally associated with hydroxocobalamin administration.