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.

Creatine kinase isoenzyme BB: a lung cancer associated marker.

We investigated the diagnostic role of creatine kinase isoenzyme BB (CK-BB) in lung cancer. CK-BB was assayed using a radioimmunological system by saturation with Mallinchrodt double antibody 125I labelled (RIA Quant-CPK-BB). Sensitivity was 97% and specificity 90% in 44 cancers (T2-T3), in 36 non-cancers (chronic bronchitis) and in 48 healthy controls. Mean serum CK-BB values for patients with chronic bronchitis (2.64 +/- 1.1 ng/ml) were virtually the same as in normal subjects. Patients with lung cancer had markedly higher serum CK-BB values (9.17 +/- 2.6 ng/ml) than either the control group (healthy subjects) or the chronic bronchitis patients (p less than 0.01). These results lead us to suggest that CK-BB serum determination might prove useful in screening pulmonary disorders. However, further studies are essential to establish: 1) the relationship between serum levels of the isoenzyme and the histology and stage of the neoplastic disease; 2) the relation between CK-BB and the aggressive potential of the neoplastic clone.

Reduction of cardiac toxicity of anthracyclines by L-carnitine: preliminary overview of clinical data.

Doxorubicin is one of the most effective antineoplastic agents but its limited use is due to acute and chronic cardiotoxicity. These side-effects are irreversible and dose-dependent, occurring in one-third of the patients treated after a cumulative dose of 300 mg/m2. It has been suggested that the problem of acute and chronic cardiotoxicity may be prevented by using L-carnitine. Hence nine patients receiving a cumulative dose (200-490 mg/m2) of doxorubicin have been studied. Acute cardiotoxicity has been evaluated by creatine kinase---marsh bender (MB) serum levels before and 15 h after treatment. Data demonstrated no significant increase of isoenzyme-MB after doxorubicin administration. Chronic cardiotoxicity has been monitored studying the electrocardiograph and the left ventricular performance by computerized M-Mode echocardiography measuring the maximal velocity of circumferential fibre shortening (VCF Max) which is considered a reliable and very sensitive non-invasive parameter to evaluate myocardial contractility. The results show a decrease in VCF Max (measured in diameter/cardiac cycle) from 1.7 +/- 0.4 to 1.4 +/- 0.3 but still within normal values. So the systematic use of L-carnitine as adjuvant therapy is proposed during doxorubicin administration.

[Indication for transcranial Doppler studies in transient ischemic attack]. / L'indagine al Doppler transcranico nell'attacco ischemico transitorio.

UNLABELLED: 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.

[Diagnosis of cardiocirculatory autonomic failure by the tilting method]. / Diagnosi della condizione di disautonomia cardio-circolatoria con il metodo di tilting.

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.

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.

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.

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.

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.