Tamara Taddei

Decreased spontaneous heart rate variability in congestive heart failure

Heart rate (HR) variability is a noninvasive index of the neural activity of the heart. Although also dependent on the sympathetic activity of the heart, HR variability is mainly determined by the vagal outflow of the heart. Several HR abnormalities have been described in patients with congestive heart failure (CHF); however, there are no data on HR variability in CHF patients. In the present study HR variability was assessed in 20 CHF patients and 20 control subjects from 24-hour Holter tapes. HR variability was evaluated by calculating the mean hourly HR standard deviation and by analyzing the 24-hour RR histogram. Mean hourly HR standard deviation was markedly and significantly reduced in CHF patients both over the 24-hour period (97.5 +/- 41 vs 233.2 +/- 26 ms, p less than 0.001) as well as during most of the individual hours examined. The 24-hour RR histogram of CHF patients had a different shape and had a decreased variation compared to control subjects (total variability 356 +/- 102 vs 757 +/- 156 ms, p less than 0.001). Thus, CHF patients with depressed ejection fraction (less than 30%) have a low HR variability compared to normal individuals. This result can be interpreted as adjunctive evidence for decreased parasympathetic activity to the heart during CHF.

Diagnostic accuracy of peak exercise echocardiography in coronary artery disease: Comparison with thallium-201 myocardial scintigraphy

To evaluate the accuracy of exercise two-dimensional echocardiography for the recognition of coronary artery disease, 53 patients (46 men and 7 women, age range 35 to 69 years) without either previous myocardial infarction or resting wall motion abnormalities, were studied. According to coronary angiography 26 had normal coronary arteries, 14 had one-vessel, seven had two-vessel, and six had three-vessel disease. After withdrawal of any therapy, all patients underwent a single exercise stress test with a stress table during which cine-loop digitized echocardiography was acquired and 74 MBq of thallium-201 (TI-201) were injected. Echocardiographic images were evaluated at rest and at peak exercise. Three-view planar scintigraphic images were collected immediately after exercise and 4 hours later. For the overall recognition of coronary artery disease, exercise electrocardiography had 77.8% sensitivity and 65.4% specificity; myocardial scintigraphy had 100% sensitivity and 92.3% specificity; and exercise echocardiography had 92.6% sensitivity and 96.2% specificity (both NS versus myocardial scintigraphy). Global accuracy was 71.7% for exercise electrocardiography, 94.3% for stress echocardiography, and 96.2% for myocardial scintigraphy. For the classification of the individual involved coronary arteries, the sensitivity of myocardial scintigraphy was 84.8% and that of exercise echocardiography was 63% (p less than 0.01); the related specificities were 98% and 98.2% respectively (NS). It may be concluded that exercise echocardiography is highly accurate for the recognition of coronary artery disease, whereas it appears less sensitive in the identification of the involved vessels, particularly in patients with multivessel disease.

The onset of symptomatic atrial fibrillation and paroxysmal supraventricular tachycardia is characterized by different circadian rhythms

Abstract Circadian patterns have been demonstrated for several biologic phenomena including cardiovascular diseases such as acute myocardial infarction and sudden death.1 Diurnal distribution of paroxysmal supraventricular arrhythmias has been less extensively investigated,2,3 but only data on hospitalized patients are available. The aim of this study was to find if a diurnal distribution could be identified in the occurrence of the different types of symptomatic supraventricular arrhythmias in patients rescued at home by the Florence Mobile Coronary Care Unit.

Thrombin generation after physical exercise

Many investigators have studied the influence of physical exercise on hemostatic system and it is well accepted that exercise causes an activation of coagulation as indicated by a shortening of aPTT and by an increase in plasma factor VIII activity and levels. A controversial point remains whether this clotting activation leads to a significant thrombin generation and fibrin formation. The type of physical exercise performed and the methods used to study blood coagulation may be two major sources of discrepancies in different studies. In the last years sensitive and reliable methods became available to evaluate prothrombin activation and thrombin generation. Thus in this study we have investigated the influence of a well standardized treadmill stress test, controlled by the measurement of cardiorespiratory and metabolic parameters, on plasma concentration of different markers of clotting activation in healthy untrained young subjects. Blood samples were also withdrawn just before anaerobic threshold to investigate a possible role of metabolic acidosis in changes of clotting system.

Role of a prehospital medical system in reducing heroin-related deaths.

ObjectiveThe mortality rate from heroin overdose in Italy between 1977 and 1987 increased significantly. However, in the same period, a significant increase was not observed in Tuscany, an administrative region in Italy. This study was performed to determine if the prehospital emergency medical system of Florence, the capital of Tuscany (the only one operating in Italy during the study period), affected this lower mortality rate. DesignRetrospective study. SettingThe Florence system consists of 17 mobile ICUs, each of which is staffed by a physician and three paramedics. These units are able to carry out advanced cardiopulmonary resuscitation with equipment transported to the scene of an emergency. PatientsA total of 126 consecutive patients with heroin overdose, assisted by four mobile ICUs from January 1, 1984 through December 31, 1987. InterventionsCommon therapeutic protocol in the treatment of heroin overdose and of cardiac arrest. ResultsFifty-two (41.3%) patients were in respiratory arrest, and seven (5.6%) patients were in cardiorespiratory arrest. The prehospital mortality rate was 1.6%, the inhospital mortality rate was 0.8%, and the overall mortality rate was 2.4%. During the period considered, the number of heroin overdose-related interventions increased significantly, as did the number of heroin overdoses complicated by respiratory arrest or by cardiorespiratory arrest, but the mortality rate remained low. ConclusionWe suggest that an emergency medical system can play an important role in reducing the mortality rate from heroin overdose.

Neuropsychological outcome of survivors of out-of-hospital cardiac arrest

Thirty patients resuscitated from out-of-hospital cardiac arrest (15 with and 15 without postanoxic coma on admission) underwent a clinical examination and neuropsychological testing. In order to assess quality of life, they were compared to two matched control groups; 15 patients with previous myocardial infarction and 15 healthy subjects. None of the survivors showed severe neurologic impairment, and all had returned to self-sufficient physical activity. However, the behavior rating scale scores were significantly worse in patients with postanoxic coma. The processing ability linked to memory was significantly worse in the postanoxic coma group. Mood disorders were also observed in this group, but they did not have pathological significance. The remarkably low incidence of neurologic and psychological sequelae in these resuscitated patients, particularly in those with early clinical evidence of severe cerebral damage, is an encouraging result that supports the therapeutic systems development and efforts in the management of out-of-hospital cardiac arrest.

Early out-of-hospital lidocaine administration decreases the incidence of primary ventricular fibrillation in acute myocardial infarction

This study was designed to assess the effectiveness of early prehospital intravenous administration of lidocaine in preventing primary ventricular fibrillation (PVF) in patients with suspected acute myocardial infarction (AMI). Sixty patients with suspected AMI, seen by the Mobile Coronary Care Unit (MCCU) of Florence, were randomly allocated at home to treatment with lidocaine (bolus i.v. of 1 mg/kg, followed by an infusion of 4 mg/min) or placebo (infusion of saline at a rate of 1 mL/min), respectively. The lidocaine group (27 patients) and the control group (33 patients) were not significantly different in age, clinical condition, or time of randomization. The diagnosis of AMI was confirmed in all 60 patients during the hospital stay. Ventricular fibrillation (VF) occurred in 5 patients in the control group in comparison to none in the lidocaine group (P < 0.05). Three patients experienced VF at home and were successfully resuscitated by an MCCU cardiologist. In another two patients, VF occurred during the first 4 hours after onset of symptoms. No major side effects were observed after the infusion of lidocaine. Our findings support the effectiveness of the prophylactic administration of lidocaine in preventing PVF in the prehospital phase of AMI and suggest that the drug can be safely administered in this setting by prehospital personnel.

Evaluation of a mobile coronary care unit protocol in patients with acute onset chest pain

This study was designed to assess the accuracy of a diagnostic protocol of the mobile coronary care unit (MCCU) of Florence for acute chest discomfort. During 1986, 706 patients with chest pain were seen by the MCCU. Of these, 324 of 376 (95.2%) of those hospitalized and 247 of 324 (76.2%) of the nonhospitalized patients were entered in the study. The MCCU diagnosis of acute myocardial infarction (AMI) was confirmed in 120 patients (80.3%). A false positive diagnosis of AMI was made in 27 patients (6.9%), while in 37 patients AMI was not diagnosed at the first MCCU clinical examination (false negative). The sensitivity in the diagnosis of AMI was 80.5%, the specificity 91.8%, and the diagnostic accuracy 89.1%. In the recognition of acute coronary syndromes (AMI + unstable angina), sensitivity and specificity were, respectively, 94.0% and 94.4%. The protocol of the Florence MCCU provides high accuracy in the diagnosis of AMI and acute coronary insufficiency; close adherence to the protocol can decrease the number and the costs of undue hospital admissions while protecting the safety of patients.

Feasibility of out-of-hospital treatment of supraventricular tachycardias

Abstract Despite the overall good prognosis, most patients with supraventricular tachyarrhythmias require hospitalization for the restoration of sinus rhythm. In the last decade, Mobile Coronary Care Units (MCCU) were instituted in several towns for the treatment of out-of-hospital cardiac arrest and to decrease prehospital times in acute myocardial infarction. 1 Cardiologist-staffed MCCUs can successfully attempt at-home cardioversion in patients with supraventricular arrhythmias, thus decreasing the number and cost of most hospitalizations. The present study reviews the results of 10 years of activity by Florences MCCU in the out-of-hospital treatment of recent onset (

Automated Blood Pressure Determination During Exercise Test. Clinical Evaluation of a New Automated Device

The accuracy and reproducibility of a new automatic device (P) specially designed for noninvasive blood pressure monitoring during the exercise stress test were evaluated in 50 consecutive subjects (34 normotensives and 16 hyper tensives). Automatic measurements were compared with those taken by a sphygmomanometer (RR). A good agreement between systolic pressure values obtained by the two methods was found (RR 159±30 mmHg, P 158 ± 28 mmHg, mean difference = -1.53 ± 13 mmHg, p = 0. 166, ns). On the contrary the new device significantly underestimated diastolic pressure values (RR 89.3 ± 13 mmHg; P 84±13 mmHg, mean difference -5.37±9.3, p < 0.001). In conclusion the new device seems able to measure systolic but underesti mates diastolic blood pressure both in hypertensives and in normotensives dur ing the effort test.