L'ipotensione

Ipotensione: concetti generali e classificazioneA. LagiIpotensione acutaG. Costantino, M. BonziIpotensione cronica non neurogenaA. LagiIpotensione neurogena nella multiple system atrophy e nella pure autonomic failureR. Furlan, F. Dipaola, R. Lembo, F. BarbicIpotensione cronica neurogena: malattia di Parkinson e demenza a corpi di LevyF. BarbicIpertensione clinostaticaA. Lagi, S. CencettiNeuropatie autonomicheA. LagiIpotensione e sincopeS. Cencetti

Serotonin vascular reactivity and other clinical pharmacological investigations in two intestinal carcinoid patients

In two patients with carcinoid syndrome, a reduced venoreactivity to serotonin (5-HT) was found by means of the venoconstriction test. Parachlorophenylalanine (PCPA) treatment increased 5-HT venoreactivity. A normal noradrenaline venoreactivity was detected before and during PCPA administration. The altered platelet monoamine oxidase (MAO) activity corrected by PCPA treatment. The abnormal 5-HT turnover may alter the synthesis of MAO and provoke the production of isoenzymes. Low plasma amine oxidase and high plasma histaminase activity were found in 1 of these 2 patients. A low level of plasma prekallikrein in the two patients remained unchanged during PCPA administration.

Incidence of hypoglycaemia associated with transient loss of consciousness. A retrospective cohort study

OBJECTIVE

To define the incidence of hypoglycaemia associated with transient loss of consciousness (TLoC).

DESIGN

Retrospective cohort study using a nested case-control analysis.

SETTING

Presentations to the emergency departments (EDs) of four general metropolitan hospitals in Azienda Sanitaria 10, Florence, Italy during 2012.

PARTICIPANTS

The cohort consisted of 133,285 patients extracted from the database of ED presentations. All patients with TLoC were identified by nurse triage, and their levels of glycaemia were recorded. Clinical investigations were undertaken using patients' charts and witness statements. Patients were matched with controls according to year of birth, year of cohort entry and gender.

RESULTS

Of the 133,285 patients, 3964 (2.9%) presented with TLoC, and 39 (1%) of the patients with TLoC had transient hypoglycaemia. Mean glycaemia in these 39 patients was 52 mg/dl (a level of 112 mg/dl was in controls). Symptoms associated with TLoC during hypoglycaemia differed from those characteristic of syncope. TLoC during hypoglycaemia mainly occurred in elderly patients with diabetes, who had relatively long disease duration, were receiving treatment, often also had renal failure and were experiencing symptoms as a result of lack of food intake. Together, these factors make it easier to diagnose hypoglycaemia associated with TLoC, and our results may prompt modification in medical practice.

CONCLUSION

Correct diagnosis of hypoglycaemia associated with TLoC has economic benefits if a protracted and costly series of clinical investigations can be avoided. A diagnosis of hypoglycaemia might also facilitate the resolution of patients' symptoms through lifestyle changes and adjustment of therapy.

Copeptin: a blood test marker of syncope

AIMS

Copeptin (CPT) is regarded as a stress hormone, and as a novel marker of acute disease, and it has never been tested for a role in diagnosing syncope. The main objectives of the study were to measure CPT in patients suffering from syncope, to determine its diagnostic sensitivity and specificity, and compare it with that in patients with falls and mild trauma. The secondary objective was to determine whether different types of syncope correlate with different levels of CPT.

METHODS

Fifty-one patients suffering from syncope and 51 suffering from falls without syncope were included in this study. Patients with a diagnosis of acute comorbidity were excluded. The diagnostic work was in accordance with the Guidelines of the European Cardiology Society. The level of CPT was measured in each patient evaluating the mean values in syncope vs. falls and in the different syncope type and the values over or under the normal threshold.

RESULTS

Of the 51 patients with syncope, 44 had abnormal and 7 normal CPT levels. Of the 51 patients with falls, 47 had normal and 4 abnormal levels of CPT. There was no difference in mean CPT levels in patients with different types of syncope. There was no correlation between levels of CPT and age or sex. There was a relationship between normal CPT levels and falls.

CONCLUSION

Copeptin is an efficient marker of syncope. It is useful for confirming or ruling out a diagnosis of syncope in patients who are unable to provide a definite history or when the event is unwitnessed.

Effect of rosary prayer and yoga mantras on autonomic cardiovascular rhythms: comparative study

OBJECTIVE

To test whether rhythmic formulas such as the rosary and yoga mantras can synchronise and reinforce inherent cardiovascular rhythms and modify baroreflex sensitivity.

DESIGN

Comparison of effects of recitation of the Ave Maria (in Latin) or of a mantra, during spontaneous and metronome controlled breathing, on breathing rate and on spontaneous oscillations in RR interval, and on blood pressure and cerebral circulation.

SETTING

Florence and Pavia, Italy.

PARTICIPANTS

23 healthy adults.

MAIN OUTCOME MEASURES

Breathing rate, regularity of breathing, baroreflex sensitivity, frequency of cardiovascular oscillations.

RESULTS

Both prayer and mantra caused striking, powerful, and synchronous increases in existing cardiovascular rhythms when recited six times a minute. Baroreflex sensitivity also increased significantly, from 9.5 (SD 4.6) to 11.5 (4.9) ms/mm Hg, P<0.05.

CONCLUSION

Rhythm formulas that involve breathing at six breaths per minute induce favourable psychological and possibly physiological effects.

Cerebral vasoconstriction in vasovagal syncope: any link with symptoms? A transcranial Doppler study

BACKGROUND

Cerebral vasoconstriction has been described previously in vasovagal syncope (VVS). This phenomenon appears paradoxical in view of the well-known decrease of systemic vascular resistances taking places during VVS. We aimed to assess (1) whether cerebral vasoconstriction in VVS is an independent paradoxical phenomenon and (2) whether cerebral vasoconstriction has any link with symptoms and/or VVS onsets.

METHODS AND RESULTS

Seven young patients with recurrent VVS participated in the study. Each patient underwent monitoring of heart rate, blood pressure, cerebral blood flow velocity (by means of transcranial Doppler), end-tidal PCO(2), peripheral oximetry, respiratory rate, and tidal volumes both at rest and during head-up tilt. All the subjects experienced tilt-induced VVS. A significant increase of respiratory tidal volumes was observed in each subject >/=160 seconds before VVS. This deep breathing induced a PCO(2) decrease and, consequently, also a decrease in cerebral blood flow velocity and increase in cerebrovascular resistance (expressed by the increase of the pulsatility index). Within 40 seconds, 5 subjects started complaining of discomfort, in the absence of any significant blood pressure drop.

CONCLUSIONS

Cerebral vasoconstriction is not a paradoxical phenomenon when it occurs before tilt-induced VVS but rather is only the physiological consequence of the hyperventilation-induced hypocapnia that occurs in habitual fainters. The large lag between the onset of syncope and cerebral vasoconstriction excludes the hypothesis that VVS is dependent on abnormal behavior of cerebral hemodynamics.

Disease-related syncope. Analysis of a community-based hospital registry

Syncope is characterized by sudden and transient loss of consciousness that follows a reduction or interruption of cerebral blood flow. The present study was designed to assess the prevalence of disease-related syncope in a wide sample of in-patients admitted for different diseases. A total of 16 809 patients (age range 18-99 years) were recruited from three hospitals in Florence in 1998. The community-based registry was reviewed to identify all patients suffering from complaints associated with syncope. Each disease-related syncope was matched with the number of patients suffering from that disease. Furthermore, each disease was expressed as a percentage of total cases included in the study. The odds ratio was calculated to determine the index of significant correlation between syncope and occasional diseases. Total syncopes were 775 (prevalence 4.46%), vasovagal syncopes were 336 (1.9% of total sample and 44% of total syncopes), and the disease-related syncopes were 439 (56% of total syncopes). We found a significant association between syncope and orthostatic hypotension, complete heart block, chronic cerebral disease, migraine, acute gastrointestinal haemorrhages and aortic stenosis. Furthermore, we found a significant association with acute gastrointestinal haemorrhage, which has not been described previously. Significant relationships emerged from our data which yield a new insight into the association between syncope and a wide range of systemic diseases.

Autonomic control of the cerebral circulation during normal and impaired peripheral circulatory control

OBJECTIVE

To determine whether oscillations in the cerebrovascular circulation undergo autonomic modulation in the same way as cardiovascular oscillations.

DESIGN

Cardiovascular and cerebrovascular oscillations were monitored at rest and during sympathetic stimulation (head up tilt). The association with and transmission of the oscillations in the sympathetic (low frequency, LF) and respiratory (high frequency, HF) bands was assessed.

SUBJECTS

13 healthy volunteers, 10 subjects with vasovagal syncope, and 12 patients with complicated non-insulin dependent diabetes mellitus.

MAIN OUTCOME MEASURES

Power spectrum analysis of cerebral blood flow velocity, arterial blood pressure, and heart rate. Coherence analysis was used to study the association between each pair of oscillations. Phase analysis showed the delay of the oscillations in the cardiovascular signals with respect to the cerebrovascular signals.

RESULTS

The power in the sympathetic (LF) components in all the oscillations increased during head up tilt (p < 0.01) in the controls and in the subjects with vasovagal syncope, but not in patients with diabetes. Significant coherence (> 0.5) in the LF band was present between cerebrovascular and cardiovascular oscillations in most of the controls and in subjects with vasovagal syncope, but not in the diabetic patients (< 50% of the patients). In the LF band, cerebrovascular oscillations preceded the cardiovascular oscillations (p < 0.05) at rest in all groups: the phase shifts were reduced (p < 0.05) during head up tilt for all cardiovascular signals in healthy and syncopal subjects, but only for heart rate in diabetic patients.

CONCLUSIONS

The cerebrovascular resistance vessels are subject to autonomic modulation; low frequency oscillations in cerebral blood flow velocity precede the resulting fluctuations in other cardiovascular signals. Autonomic neuropathy and microvascular stiffness in diabetic patients reduces this modulation.

Autonomic control of heart rate variability in vasovagal syncope: a study of the nighttime period in 24-hour recordings

Patients experiencing vasovagal syncope have been claimed to show reduced vagal tone over 24-hour electrocardiography recordings. Assessment of sympathovagal balance in the absence of external stimuli, i.e., nighttime electrocardiography monitoring, might help to clarify if increased sympathetic activity is present in these patients. Heart rate variability was examined at nighttime in 40 patients with recurrent episodes of vasovagal syncope within the last 2 years (22 men; mean age, 37 years) and 20 comparable healthy volunteers. Time domain parameters (pNN50 [proportion of successive RR intervals difference >50 ms in %] and rMSSD [root-mean-square successive difference of RR intervals in ms]), indexes of vagal tone, and frequency domain parameters, expressing the overall heart rate variability, vagal (high frequency [HF]) and sympathetic (low frequency [LF]) activity, and autonomic balance (LF/HF ratio) were compared between groups by Mann-Whitney test. Significant (p<0.05) reduction of heart rate variability and vagal tone (pNN50 and rMSSD) were found for patients with vasovagal syncope, together with increased sympathetic activity (increased LF/HF ratio). These findings could open new insights in the pathogenesis of vasovagal syncope because of the shift of the autonomic balance toward sympathetic activation near the syncopal episode.

Age-related changes of cardiac parasympathetic modulation after vasovagal syncope

The time-domain analysis of 24-hour electrocardiographic recordings showed that vagal modulation of heart rate is reduced within 48 hours from vasovagal syncope. However, patients with recent vasovagal syncope can be differentiated from healthy subjects only up to the age of 40 years with this analysis, because this parasympathetic modulation physiologically decreases with increasing age.

The "Harlequin Sign". Case description and review of the literature

Asymmetrical facial sweating and flushing has been named the "Harlequin Sign". This is a rare feature, as evident from only 12 cases described up to date. The "Harlequin Sign" represents a local autonomic dysfunction due to a cervical sympathetic deficit located at the pre or postganglionic level on the non-flushing side. We observed slow onset and progression of the "Harlequin Sign" in a 19-year-old man, with preexisting slight miosis on the non-flushing side. The differential diagnosis included other forms of dysautonomia and a secondary origin of this partial Horner's syndrome. Both pupils normally reacted to light, convergence, and pilocarpine eye-drop instillation, but the affected side showed supersensitivity to phenylephrine. Deep tendon reflexes were normal, thus excluding Adie's syndrome. The absence of cholinergic supersensitivity in the iris muscles indicated normal function of the ciliary ganglion and excluded the ocular parasympathetic deficit, also evident for the coexisting Horner's syndrome. The clinical features could be explained by assuming that the lesion was located at the level of postganglionic sympathetic fibers, probably due to trans-synaptic postganglionic neuronal degeneration at the level of the stellate ganglion, thus determining the onset of the hemifacial symptoms.

Cerebral autoregulation in patients with cirrhosis and ascites. A transcranial Doppler study

BACKGROUND/AIMS

Patients with cirrhosis and ascites usually show alterations of systemic hemodynamics and are thus prone to develop arterial hypotension, which might result in cerebral hypoperfusion if cerebral autoregulation is impaired.

METHODS

We evaluated cerebral autoregulation in 15 patients with cirrhosis and ascites and 15 healthy subjects by monitoring mean blood flow velocity in the middle cerebral artery and arterial pressure during supine rest and passive tilting.

RESULTS

Tilt provoked a drop of arterial pressure in both groups. Control subjects had a prompt recovery of mean flow velocity and a progressive recovery of arterial pressure, so that, after 120 s, both parameters had returned to baseline: at 20 s the recovery of flow velocity was faster (p<0.01) than that of blood pressure. By contrast, patients with cirrhosis had a delayed and incomplete recovery of both parameters (p<0.01 vs healthy subjects). In eight patients, the recovery of mean flow velocity paralleled that of arterial pressure, indicating an impaired cerebral autoregulation. These patients had a worse liver function, a higher cardiac index and lower peripheral resistance.

CONCLUSIONS

Cerebral autoregulation is often impaired in patients with cirrhosis and ascites. These patients can develop cerebral hypoperfusion if arterial pressure falls abruptly.

Vagal control of heart rate variability in vasovagal syncope: studies based on 24-h electrocardiogram recordings

The autonomic nervous system has an important role in the pathophysiology of vasovagal syncope. The purpose of this investigation was to evaluate to what extent the autonomic system is involved in the mechanism of fainting and to characterize the profile of heart rate variability of individuals who are prone to undergo a critical event. Thirty patients (mean age 41 years) with vasovagal syncope and 15 comparable controls were monitored by 24-h electrocardiography. Heart rate variability was analysed over the whole 24 h and during the daytime and night-time using time domain parameters (average of heart periods, RR; standard deviation of heart periods, SDNN; standard deviation of the average of RR intervals over all the 5-min segments of the entire recording, SDANN; percentage of the total number of all RR intervals of pairs of adjacent RR intervals differing more than 50 ms over the entire recording, pNN50; the square root of the sum of the square of differences between adjacent RR intervals, rMSSD), as indicated by the Task Force for Clinical Use of Standard Measurements of Heart Rate Variability. These parameters explore the influence of the autonomic nervous system on sinus node function and provide information about the vagal control to the heart. Among these parameters, pNN50 and rMSSD were significantly reduced in individuals with vasovagal syncope when compared with controls, over each time period considered. The two parameters are related to high-frequency oscillations in the frequency domain and to the vagal influence of the heart. These results indicate that the vagal tone to the heart is altered in subjects who suffer from vasovagal syncope. The results of this study provide an insight into the pathophysiological mechanism of fainting and may offer another means of evaluating patients with syncope.

Effect of PCO2 changes induced by head-upright tilt on transcranial Doppler recordings

BACKGROUND AND PURPOSE

Transcranial Doppler (TCD) monitoring of mean blood flow velocity (mV) during head-upright tilt can allow testing of cerebral autoregulation. Nonetheless, head-upright tilt can induce changes in the ventilation-perfusion relationship and/or respiratory activity that might influence TCD data.

METHODS

Forty-eight healthy volunteers underwent monitoring of mV and end-tidal CO2 in the horizontal position and during head-upright tilt.

RESULTS

Both mV and end-tidal CO2 significantly decreased in orthostasis (P < .01). Linear regression analysis showed a significant linkage between end-tidal CO2 and mV changes (r = .83, P < .01).

CONCLUSIONS

Changes in ventilation-perfusion ratio and in the respiratory pattern induced by head-upright tilt can significantly influence TCD data by determining a PCO2 decrease.

Noninvasive assessment of posterior cerebral artery stenosis inducing hemiplegia

Posterior cerebral artery infarction usually causes hemianopsia and, occasionally, symptoms referred to infarction in the territory of the middle cerebral artery. We describe a case of cerebral infarction of the posterior cerebral artery territory that mimicked middle cerebral artery occlusion. A patient with infarction of the right surface and deep territories of the posterior cerebral artery presented with left hemiplegia and left homonymous hemianopsia. Brain computed tomography and magnetic resonance investigation disclosed a hypodense lesion in the occipital right lobe and the medial and inferior part of the right temporal lobe. Transcranial Doppler studies disclosed an abnormally increased blood flow velocity in the proximal posterior cerebral artery and a sharp reduction in distal flow velocity. This case underscores the utility of noninvasive techniques to diagnose posterior artery stenosis: they were not only more economical than angiography but also spared the patient discomfort and risk.

Heart rate and blood pressure variability in orthostatic syncope

The pathogenetic role of autonomic nervous system in the neurally mediated orthostatic vasodepressive syncope is unclear. upright tilt was used to assess the characteristics of autonomic tone during orthostatic stress. We studied 18 patients (mean age 26 +/- 5 years) suffering from vasodepressive orthostatic syncope and with positive response to a 30-minute 60 degrees upright tilt and a comparable control group with a negative response to the upright tilt test. Blood pressure and heart rate (RR Interval) were measured beat-by-beat; ECG, systolic (SAP) and diastolic arterial pressure (DAP) and respiration trace were recorded for spectral analysis. The most important result of the work is a different pattern of the parameters evaluated, between fainters and controls, in the last period of tilt test, just before the syncope, and in the fainters group between the first (at the beginning) and the last period (just before syncope) of tilting. Baseline heart rate, arterial pressure and spectral indices were similar and increased with tilting in both groups (Low Frequency: LF; High Frequency: HF; LF/HF ratio). Just before the syncope, we observed in fainters group a decrease of heart rate, blood pressure, LF-RR, LF-DAP, LF-SAP, LF/HF -RR, and an increase of HF-RR and of total power where compared to in the same subjects in the first period of tilt and in front of controls in the same period of tilt. The novel aspect of the work, regarding the autonomic control of heart rate and arterial pressure, expressed by spectral fluctuations and by haemodinamic parameters, is consistent with a reduced sympathetic reserve in the immediate pre-syncopal period.

Impaired cardiovascular autonomic response to passive tilting in cirrhosis with ascites

The autonomic regulation of cardiovascular function was evaluated in 15 cirrhotic patients with ascites and in 13 healthy subjects by the autoregressive power spectral analysis (PSA) of the intervals between adjacent R waves of the electrocardiogram (RR) interval and arterial pressure variability. Total power, low frequency (LF; index of the sympathetic activity of the heart and circulation), and high frequency (HF; index of vagal tone to the heart) components of the RR interval, systolic, and diastolic arterial pressure were evaluated in the supine position and during passive tilting, together with plasma norepinephrine levels. In the supine position, no significant differences in the PSA data were observed between the control subjects and cirrhotic patients, who had higher plasma norepinephrine levels. In healthy subjects, tilting was associated with an increase in the LF of the RR interval and arterial pressure and a decrease in the HF of the RR interval. In contrast, patients with cirrhosis showed a decrease of both LF and HF. Consequently, the LF/HF ratio significantly increased in healthy subjects, whereas it was unchanged in cirrhotic patients. The LF component of the diastolic pressure also decreased during tilting in cirrhotic patients. Plasma norepinephrine increased after tilting in both groups. These results indicate that the autonomic response to passive tilting is impaired in cirrhotic patients with ascites at both the cardiac and vascular levels, as a result of an altered sympatho-vagal balance, with reduced sympathetic predominance. These alterations occurred despite an appropriate response to the tilting of plasma norepinephrine, pointing to a receptorial or postreceptorial site of the autonomic impairment.

[Physical exercise and increase in arterial pressure and temperature in a female heterozygote for anhidrotic ectodermal dysplasia]

A 51-year-old woman suffered from an increase in body temperature from 37 degrees to 38.4 degrees C after physical exercise. She did not sweat. The patient also had labile hypertension with maximum values reaching 210/130 mmHg. Tests were carried out to explore the possibility of a link between the increase in body temperature and her hypertension. Evaluation of the patient's blood pressure and temperature changes after exercise and after environmental modification suggests a pathogenetic link between hyperthermia and hypertension.

[Indication for transcranial Doppler studies in transient ischemic attack]

The diagnostic procedures for the assessment of transient ischemic attacks (TIA) include both brain imaging (computed tomography, nuclear magnetic resonance) and cerebrovascular investigation by means of ultrasound studies and angiography. Transcranial Doppler sonography (TCD) has not yet become a widely used diagnostic tool, although it allows noninvasive investigation of the intracranial cerebral circulation. The aim of this study was to assess the value of TCD investigation in patients who suffered from TIA. Eighty-one consecutive patients admitted to our General Medicine Department with a diagnosis of TIA underwent cranial computed tomography, ultrasound investigation of the extracranial cerebral arteries, and TCD.

RESULTS

39% of the TCD findings were not significant; TCD findings were highly significant in 18% of the patients with TIA, mainly for intracranial arterial stenoses and symptomatic subclavian steal; the other abnormal TCD findings were nonspecific, but in all these cases TCD yielded information on the efficiency of intracranial collateralization and the mechanisms regulating cerebral hemodynamics. These results suggest that TCD is a useful tool for the assessment of TIA.

Observations on the arterial baroreflex in neurally mediated vasodepressor syncope

The arterial baroreflex was studied in subjects who had recently had an episode of vasodepressor syncope. This was determined using 2-3 mcg/kg intravenous boluses of phenylephrine and assessing the bradycardic response. The values were measured in ms/mmHg and expressed as the angular coefficient of the regression line between the increase in R-R interval on the electrocardiograph and the systolic arterial pressure. In subjects examined immediately after the vasodepressor syncope episode the bradycardic response was much more marked than in controls (p < 0.01) and in the subjects themselves 6 months after the episode, provided that they were symptom-free (p < 0.01). It is concluded that in vasodepressor syncope there is a phase in which the baroreflex is highly sensitive and that this is due not to a lowering of the stimulation threshold but to a gain in the efferent arc, which explains a 'vagotonic' response.

Power spectrum analysis of heart rate variations in the early detection of diabetic autonomic neuropathy

Power spectrum analysis of the R-R interval was used in 20 controls and in two groups of type I (insulin dependent) diabetics (27 patients) to detect changes in total power or in its components (low frequency and high frequency) that might be considered an early evidence of impairment of cardiac autonomic nervous system control. A significant difference between controls and severe diabetics (with autonomic involvement) was found in all components. In the early stage of diabetes without evidence of autonomic involvement, an absolute reduction of the low frequency component in the standing position and a significant reduction of the percentage increase compared with the lying position, was found to discriminate diabetics from controls. The occurrence of somatic neuropathy was unrelated to changes in autonomic function. These data indicate that: (1) power spectrum analysis is sensitive enough to detect cardiac autonomic neuropathy in diabetics, where standard methods fail; (2) power spectrum analysis is the method of choice in the early stages; (3) in severe type I dependent diabetes there is a reduction of power spectrum analysis total power and a defective response to standing up; (4) cardiac autonomic neuropathy develops independently from somatic neuropathy.

Cerebral autoregulation in orthostatic hypotension. A transcranial Doppler study

BACKGROUND AND PURPOSE

Transcranial Doppler measurements of blood flow velocity permit an assessment of variations in intracranial hemodynamics in response to acute arterial pressure variations. The purpose of this study was to scan healthy volunteers and patients with autonomic failure for differences in cerebral hemodynamic patterns under an acute hypotensive stimulus.

METHODS

We used transcranial Doppler monitoring of blood flow velocity in the middle cerebral artery and noninvasive monitoring of arterial blood pressure and heart rate before, during, and after acute arterial hypotension induced by reactive hyperemia of the lower limbs.

RESULTS

After maximum hypotension, the mean blood flow velocity was higher in the healthy volunteers than in the patients. In the healthy subjects mean velocity rose significantly (P < .01) higher than arterial blood pressure after 30 seconds and 60 seconds; in the patients mean velocity and arterial pressure moved in parallel fashion. The diastolic blood flow velocity increased more in the control group than in the patients during the early stages of the test; furthermore, only in the healthy volunteers did it increase significantly more than arterial pressure after 30 seconds and 60 seconds. Regarding the pulsatility index, the differences between the two groups were similar to the diastolic velocity results.

CONCLUSIONS

(1) Monitoring of mean blood flow velocity showed the ability to maintain an adequate cerebral blood flow in healthy subjects; this mechanism was not efficient in the patients with autonomic failure. (2) Diastolic velocity and pulsatility index values clearly showed that only in healthy subjects were cerebral hemodynamics relatively independent of pressure values.

Blood pressure and heart rate relationship in normotensive and hypertensive subjects

A twenty-four-hour blood pressure (BP) monitoring was performed in 20 normotensive and 20 hypertensive subjects, matched by sex and age. Blood pressure and heart rate (HR) variability were evaluated both as absolute and percent standard deviation. In agreement with the literature no significant difference in HR and BP variability was observed between the two groups. The linear regression between HR and BP values was evaluated in both groups. The authors observed a significant difference in the relationship between these two cardiovascular variables between the two groups. In the hypertensive group the cardiovascular control of HR and BP showed a different relationship than in normotensive subjects, suggesting a different neurovegetative modulation.

Mitotic activity in colorectal mucosa of healthy subjects in two Italian areas with different dietary habits

The proliferative activity was evaluated in colorectal biopsies of 39 healthy subjects living in two distinct geographical areas, Trieste in northern and Florence in central Italy. Subjects living in Trieste had a significantly higher mitotic activity compared with subjects living in Florence (mitoses/cells counted x 100 were 0.17 +/- 0.04 in Trieste and 0.089 +/- 0.02 in Florence). The results of a dietary questionnaire also showed that subjects in Trieste consumed significantly fewer starches, fibers, nitrites, and proteins. However, no correlation was evident between the consumption of these nutrients and intestinal proliferation.

[Pulmonary embolism. A case report of right atrial thromboembolism treated by thrombolysis]

This case report describes a 40-years-old man affected by fracture of leg and pulmonary embolism. Two-dimensional echocardiography showed a large right atrial migrant thromboembolus prolapsing into tricuspid valve during diastole. The patient was treated with rt-PA through right atrial venous catheter and underwent to serial echocardiographic examinations. The rt-PA determined the dissolution of the thrombo-embolus at the 2nd hour of infusion. It is concluded that early two-dimensional echocardiography might be a very helpful technique to diagnose and follow-up therapy of pulmonary embolism.

[Diagnosis of cardiocirculatory autonomic failure by the tilting method]

The variation of SBP, DBP and HR is evaluated on tilting in a group of 34 patients affected by orthostatic hypotension versus a group of 54 healthy subjects, age and sex cross-matched. The patients affected by cardiovascular autonomic failure showed: 1) a fall of SBP greater than -19 mmHg in the 1st min; 2) a fall of the SBP average value (for 10 minutes) greater than -22 mmHg. Contrarily, the healthy subjects showed: 1) no variations of SBP values during the 1st minute and 2) a growing of SBP between the 2nd and the 10th minute; 3) a SBP average value (for 10 minutes) with a positive trend. The DBP and HR showed not differences between the groups. We suggest that the measure of SBP on standing may be considered an easy and fast method to perform a diagnosis of autonomic cardiovascular failure.

The tilting cardiovascular response in orthostatic syncope

159 patients with a previous discharge diagnosis of recurrent vasodepressor syncope associated with prolonged standing or other circumstance known to trigger the condition were examined in order to isolate the orthostatic form. 72 patients with a history of at least two episodes of loss of consciousness after standing still for at least 10' were selected for testing by head-up tilt. Those who showed signs or symptoms during the test were tested a further twice, the third time after atropine administration. This process resulted in the diagnosis of orthostatic vasodepressor syncope in 28 patients who presented both 1) a positive test associated with hypotension and bradycardia and 2) bradycardia-free hypotention on repetition of the test with atropine.

Detection of normotension, borderline and hypertension cutoffs in a population evaluated by non invasive blood pressure monitoring

The 24-hour blood pressure (BP) average value in normotensive and hypertensive subjects is not defined. In 329 subjects three occasional blood pressure data were measured. The same day a non invasive 24-hour blood pressure monitoring was performed. The average of the occasional blood pressure and the average of the 24-hour blood pressure data were compared. In many cases the occasional blood pressure average was not strictly linked with the 24-hour blood pressure average. A statistical procedure (K-Means Cluster Analysis) was performed separately on occasional blood pressure values and on the hourly blood pressure average of the whole day. By this method three clusters of subjects were selected to evaluate the occasional and the 24-hour blood pressure cluster's cutoffs. The cluster's blood pressure cutoffs evaluated on occasional blood pressure values were not dissimilar from the blood pressure values suggested by literature for normotensive, borderline and hypertensive groups. The K-Means Clusters Analysis seems an interesting statistical method to research the subsets in a population evaluated by 24-hour blood pressure monitoring. We suggest that the 24-hour BP cutoffs evaluated in the three cluster groups may be considered as indicative for a clinical diagnosis of normotensive, borderline and hypertensive state.

[Hypersensitivity of the carotid sinus in syncope and its diagnostic role: therapeutic implications and follow-up]

Our aim was to assess the incidence and clinical characteristics of carotid sinus hypersensitivity in a group of subjects suffering from syncope. The total number of patients was 118. Twenty-four of them (20%) were diagnosed as epileptics (first attack) and 38 (32%) as vasodepressors. 56 patients with unexplained syncope underwent carotid sinus massage during electrocardiographic registration and pressure monitoring. 41 patients were found to have carotid sinus hypersensitivity. 34 of these 41 patients received implantation of a pacemaker. Abnormal sinus node function was noted in 30, abnormal atrioventricular node function in 3 and combined abnormal sinus node and AV node function in 1. Furthermore three other patients who were negative to massage were implanted with a pacemaker because they had an organic heart disease and recurrent syncope. Different tests as 24-hour monitoring ecg and electrophysiologic study showed no better results in the diagnosis of syncope. Our data demonstrates the diagnostic importance of carotid sinus massage in the diagnosis of syncope. The validity of this method is confirmed by the 24 month follow-up.

[Incidence of exertion hypertension in normotensive individuals]

Exercise hypertension is the blood pressure response to dynamic exercise stress which is considered excessive as compared to what is normally observed in a healthy population. It is a useful indicator to assist in detecting those persons who may develop sustained hypertension. Research has been conducted on a large number of patients, carefully selected using as criteria: arterial pressure, presence of other diseases and age. The examination has been conducted by observing the stressor test on the cycloergometer and annotating the Pa with the traditional method. The data was then analyzed using statistical methods. We conclude that at the moment of maximum effort the patients can be divided into two groups based upon PaD values superior or inferior to 20% of base values or to 95 mmHg. Those who exceed these values (43% of all patients studied) are considered as effort hypertensive subjects. The work's originality derives from the statistically proven consideration that the evaluation of PaD at the 8th minute of the test with cardiac rate between 70 and 90% of the maximum theoretical cardiac rate is predictive of effort hypertension. Hence continuation of the test can be avoided with advantages in terms of time and reduction of the generic risks inherent in carrying out a maximal test. Follow up on the patients is in progress.

The Valsalva maneuver in vasodepressor syncope

In this work the authors propose the Valsalva maneuver as a diagnostic test in a group of patients shown, by anamnestic, physical, and instrumental criteria, to be affected by vasodepressor syncope. They studied the response of heart rate and baseline arterial pressure to the maneuver performed in passive orthostasis in 7 healthy volunteers and 24 patients. These patients showed a hypotensive response and a time of recovery to the initial values that was significantly longer than in the control group (p less than 0.01). The authors conclude that studying the response to the Valsalva maneuver can be useful in the diagnosis of vasodepressor syncope.