This study documents relationships between handedness and carotid arterial asymmetries. The article is divided into two sections, considering first geometric (n = 195) and then haemodynamic (n = 228) asymmetries. In the geometric study, diameters, lengths, and angles of the common carotid arteries in left and right-handed participants were measured using computed tomography angiography scans. Resistance to blood flow was calculated according to Poiseuille's formula. In the haemodynamic study, peak systolic and end-diastolic velocity, vessel diameter, and volume flow rate of the common, internal, and external carotid arteries were measured in left and right-handed participants, using Doppler ultrasonography. The findings reveal for the first time that the extracranial arteries supplying the cerebral hemispheres are asymmetrical in a direction that increases blood flow to the hemisphere dominant for handedness. Significant handedness interactions were identified in arterial length, diameter, resistance to blood flow, velocity and flow volume rate (p < .001). Arterial resistance and volume flow rates significantly predicted hand preference and proficiency. Our findings reveal a vascular correlate of handedness, but causality cannot be determined from this study alone. These asymmetries appear to be independent of aortic arch anomalies, suggesting a top-down, possibly demand-driven, pattern of development.

BackgroundEarly presentation is desirable in all cases of acute prolonged chest pain. Causes of delayed presentation vary widely across geographic regions because of different patients' profile and different healthcare capabilities.ObjectivesTo detect causes of delay of Non-ST elevation acute coronary syndrome (NSTE-ACS) patients in our country.MethodsPatients admitted with NSTE-ACS were included. We recorded the time delay between the onsets of acute severe symptoms till their arrival to the hospital (Pre-hospital delay). We also recorded the time delay between the arrival to hospital and the institution of definitive therapy (hospital delay). Causes of pre-hospital delay are either patient- or transportation-related, while hospital delay causes are either staff- or system-related.ResultsWe recruited 315 patients, 200 (63.5%) were males, 194 (61.6%) hypertensives, 180 (57.1%) diabetics, 106 (33.7%) current smokers and 196 (62.2%) patients had prior history of cardiac diseases. The mean pre-hospital delay time was 8.7 ± 9.7 h. Sixty-six percent of this time was due to patient-related causes and 34% of pre-hospital delay time was spent in transportation. The mean hospital delay time was 2.3 ± 0.95 h. In 89.8% of cases, the hospital delay was system-related while in 10.2% the reason was staff-related. The mean total delay time to definitive therapy was 11.0 ± 9.8 h.ConclusionPre-hospital delay was mainly patient-related. Hospital delay was mainly related to healthcare resources. Governmental measures to promote ambulance emergency services may reduce the pre-hospital delay, while improving the utilization of healthcare resources may reduce hospital delay.