Head-out water immersion induces marked increase in the cardiac stroke volume. The present study was undertaken to characterize the stroke volume change by analyzing the aortic blood flow and left ventricular systolic time intervals. Ten men rested on a siting position in the air and in the water at 34.5degreeC for 30 min each. Their stroke volume, heart rate, ventricular systolic time intervals, and aortic blood flow indices were assessed by impedance cardiography. During immersion, the stroke volume increased 56%, with a slight (4%) decrease in heart rate, thus cardiac output increased ~50%. The slight increase in R-R interval was due to an equivalent increase in the systolic and diastolic time intervals. The ventricular ejection time was 20% increased, and this was mainly due to a decrease in pre-ejection period (28%). The mean arterial pressure increased 5 mmHg, indicating that the cardiac afterload was slightly elevated by immersion. The left ventricular end-diastolic volume index increased 24%, indicating that the cardiac preload was markedly elevated during immersion. The mean velocity and the indices of peak velocity and peak acceleration of aortic blood flow were all increased by ~30%, indicating that the left ventricular contractile force was enhanced by immersion. These results suggest that the increase in stroke volume during immersion is characterized by an increase in ventricular ejection time and aortic blood flow velocity, which may be primarily attributed to the increased cardiac preload and the muscle length-dependent increase in myocardial contractile force.
Acceleration ; Arterial Pressure ; Blood Flow Velocity ; Cardiac Output ; Cardiography, Impedance ; Heart Rate ; Humans ; Immersion* ; Male ; Stroke Volume ; Systole ; Water*

It is generally known that demonstration of absence of cerebral blood flow is necessary to confirm brain death. Transcranial Doppler(TCD) is an accurate method of monitoring the blood flow velocities of the cerebral vessels. We performed transcranial doppler(TCD) examinations on 15 patients in brain death. Anterior circulation was examined through the temporal window or transorbital window and basilar arteries were examined through the suboccipital window. All of the patients fulfilled the criteria for determination of brain death by clinical criteria, EEG and/or Brainstem Auditory Evoked Response(BAER) or clinical criteria alone, were mechanically ventilated. A TCD waveform abnormality consisting of reversed diastolic components was found in all brain death patients. The net flow velocities of <10cm/sec were present in all brain death patients. TCD may be a rapid and convenient alternative to cerebral angiography for confirming brain death when institutional protocols require such confirmation.
Basilar Artery ; Blood Flow Velocity ; Brain Death* ; Brain Stem ; Brain* ; Cerebral Angiography ; Electroencephalography ; Humans

The computational fluid dynamics methods for the limited flow rate and the small dimensions of an intracranial artery stenosis may help demonstrate the stroke mechanism in intracranial atherosclerosis. We have modeled the high wall shear stress (WSS) in a severe M1 stenosis. The high WSS in the systolic phase of the cardiac cycle was well-correlated with a thick fibrous cap atheroma with enhancement, as was determined using high-resolution plaque imaging techniques in a severe stenosis of the middle cerebral artery.
Blood Flow Velocity ; *Cerebral Angiography ; Cerebrovascular Circulation ; Computational Biology ; Humans ; Image Interpretation, Computer-Assisted ; Imaging, Three-Dimensional ; Intracranial Arteriosclerosis/*diagnosis ; *Magnetic Resonance Angiography ; Shear Strength ; Software ; Systole

Aortic dissection is clinically suspected from the typical symptoms and signs and may be confirmed by computed tomography or aortography. But atypical presentations can be seen in a minority of cases, such as SVC syndrome, right pulmonary artery stenosis etc. We present a case which was initially suspected to be a right atrial tumor because of a large filling defect in the right atrium on radionuclide angiocardiography but finally confirmed to be dissection of ascending aorta by computed tomography.
Angiocardiography ; Aorta ; Aortography ; Constriction, Pathologic ; Heart Atria ; Pulmonary Artery

OBJECTIVE: We evaluate the role of multislice computerized tomographic angiography(MCTA) in the diagnosis of intracranial vasospasm following subarachnoid hemorrhage(SAH) in patients suspected of having vasospasm on clinical ground. METHODS: Between October 2003 and June 2005, patients with ruptured cerebral aneurysms of the anterior circulation clipped within 3 days of the onset were included. We performed follow-up MCTAs in patients who were suspected to have vasospasm on transcranial doppler sonography(TCD) findings and clinical grounds. Based on the clinical presentation of symptomatic vasospasm, we investigated the correlation between clinical, TCD, and MCTA signs of vasospasm and evaluated the role of MCTA in vasospasm. RESULTS: One hundred one patients met the inclusion criteria and symptomatic vasospasm developed in 25 patients (24.8%). We performed follow-up MCTAs in 28 patients. MCTA revealed spasm in the vessels of 26 patients. The sensitivity of MCTA was 100%. Among the 26 patients with MCTA evidence of vasospasm, 3 patients had TCD signs of vasospasm after symptomatic vasospasm presentation. Another 3 patients with symptomatic vasospasm had no TCD signs of vasospasm in daily serial recordings. Six other patients without symptomatic vasospasm showed MCTA evidence of vasospasm (false positive result) but these patients had also positive TCD signs of vasospasm. Volume rendering(VR) images tended to show significantly more exaggerated vasospasm than maximum intensity projection(MIP) images. The mean cerebral blood flow velocity of both proximal segment of the middle cerebral artery (M1) was significantly correlated with each reduced M1 diameter on MCTA (P<0.05). CONCLUSION: MCTA could be a useful tool for evaluation and planning management of critically ill patients suspected of having vasospasm; however, more randomized controlled trials are necessary to assess these points definitively.
Aneurysm* ; Angiography* ; Blood Flow Velocity ; Critical Illness ; Diagnosis ; Follow-Up Studies ; Humans ; Intracranial Aneurysm ; Middle Cerebral Artery ; Spasm ; Subarachnoid Hemorrhage* ; Ultrasonography, Doppler, Transcranial ; Vasospasm, Intracranial

OBJECTIVE: Aberrant right subclavian artery (ARSA) is a rare anatomical variant of the origin of the right subclavian artery. ARSA is defined as the right subclavian artery originating as the final branch of the aortic arch. The purpose of this study is to determine the prevalence and the anatomy of ARSA evaluated with computed tomography (CT) angiography.METHODS: CT angiography was performed in 3460 patients between March 1, 2014 and November 30, 2015 and the results were analyzed. The origin of the ARSA, course of the vessel, possible inadvertent ARSA puncture site during subclavian vein catheterization, Kommerell diverticula, and associated vascular anomalies were evaluated. We used the literature to review the clinical importance of ARSA.RESULTS: Seventeen in 3460 patients had ARSA. All ARSAs in 17 patients originated from the posterior aspect of the aortic arch and traveled along a retroesophageal course to the right thoracic outlet. All 17 ARSAs were located in the anterior portion from first to fourth thoracic vertebral bodies and were located near the right subclavian vein at the medial third of the clavicle. Only one of 17 patients presented with dysphagia.CONCLUSION: It is important to be aware ARSA before surgical approaches to upper thoracic vertebrae in order to avoid complications and effect proper treatment. In patients with a known ARSA, a right transradial approach for aortography or cerebral angiography should be changed to a left radial artery or transfemoral approach.
Angiography ; Aorta, Thoracic ; Aortography ; Catheterization ; Catheters ; Cerebral Angiography ; Clavicle ; Deglutition Disorders ; Diverticulum ; Humans ; Korea ; Prevalence ; Punctures ; Radial Artery ; Subclavian Artery ; Subclavian Vein ; Thoracic Vertebrae

Blood Flow Velocity ; Coronary Angiography ; Coronary Vessels

BACKGROUND AND OBJECTIVE: Magnetocardiography (MCG) is a noninvasive method for the registration of the magnetic component of electromagnetic fields in the heart that arise from electrical activity during the cardiac cycle. It has a theoretical advantage, over ECG, for the detection of coronary artery disease (CAD), mainly due to its higher sensitivity for local currents and better spatial resolution. However, its clinical value in the diagnosis of CAD, compared to other diagnostic tools, remains untested. The feasibility of MCG for detecting myocardial ischemia was studied. SUBJECTS AND METHODS: Ninety three patients (54 male, 39 female) with chest pain were enrolled in this study. Patients with a pacemaker or other metal implants, as well as those in unstable conditions, were excluded. Coronary angiography was performed on all the patients, following ECG and MCG measurements, on the same day. Coronary artery disease was diagnosed when intraluminal narrowing was greater than 70%. The ECG and MCG findings were compared to those of the coronary angiography, which was used as the gold standard. RESULTS: Forty two patients were diagnosed with CAD by the coronary angiography. The sensitivities and specificities of MCG and ECG for detecting a CAD were 76.2 and 47.1%, and 38.1 and 86.3%, respectively. Seventy patients showed non-diagnostic ECG for CAD. The sensitivity and specificity of MCG for detecting a CAD in this group of patients were 69.2 and 52.3%, respectively. CONCLUSION: MCG is a novel noninvasive technique for the diagnosis of coronary artery disease, but further investigation for the optimization of the efficacy of this technology will be required.
Chest Pain ; Coronary Angiography ; Coronary Artery Disease* ; Coronary Vessels* ; Diagnosis ; Diagnostic Techniques, Cardiovascular ; Electrocardiography* ; Electromagnetic Fields ; Heart ; Humans ; Magnetocardiography* ; Male ; Myocardial Ischemia ; Sensitivity and Specificity

A handy-type monitoring system for cardiovascular haemodynamic functions based on the volume-compensation and electrical admittance method is developed. In this system, the inconvenient and discomfort due to cuff occlusion of the biological segment for BP measurement is improved by developing a new device using a local pressurization method, the stability for the physiological information detection is improved by developing a new detecting system, and the noise during detection using the system is greatly reduced by using a newly developed nozzle-flapper type electro-pneumatic converter. Also, for electrical admittance cardiography to estimate CO, the applicability of a two-compartment coaxial cylindrical model and the optimal position of a spot-electrode array that is used to replace the conventional band-electrode are discussed in this research. Experimental result shows that the monitoring system should satisfy non-invasive BP and CO measurement on beat by beat, and the comfort of measurement is significantly improved.
Cardiovascular Diseases ; prevention & control ; Diagnostic Techniques, Cardiovascular ; instrumentation ; Equipment Design ; Hemodynamics ; Monitoring, Physiologic ; instrumentation ; methods

BACKGROUND/AIMS: Although drug-eluting stents (DESs) effectively reduce restenosis following percutaneous coronary intervention (PCI), they also delay re-endothelialization and impair microvascular function, resulting in adverse clinical outcomes. Endothelial progenitor cell (EPC) capturing stents, by providing a functional endothelial layer on the stent, have beneficial effects on microvascular function. However, data on coronary microvascular function in patients with EPC stents versus DESs are lacking. METHODS: Seventy-four patients who previously underwent PCI were enrolled in this study. Microvascular function was evaluated 6 months after PCI based on the index of microvascular resistance (IMR) and the coronary flow reserve (CFR). IMR was calculated as the ratio of the mean distal coronary pressure at maximal hyperemia to the inverse of the hyperemic mean transit time (hTmn). The CFR was calculated by dividing the hTmn by the baseline mean transit time. RESULTS: Twenty-one patients (age, 67.2 +/- 9.6 years; male:female, 15:6) with an EPC stent and 53 patients (age, 61.5 +/- 14.7 years; male:female, 40:13) with second-generation DESs were included in the study. There were no significant differences in the baseline clinical and angiographic characteristics of the two groups. Angiography performed 6 months postoperatively did not show significant differences in their CFR values. However, patients with the EPC stent had a significantly lower IMR than patients with second-generation DESs (median, 25.5 [interquartile range, 12.85 to 28.18] vs. 29.0 [interquartile range, 15.42 to 39.23]; p = 0.043). CONCLUSIONS: Microvascular dysfunction was significantly improved after 6 months in patients with EPC stents compared to those with DESs. The complete re-endothelialization achieved with the EPC stent may provide clinical benefits over DESs, especially in patients with microvascular dysfunction.
Aged ; Blood Flow Velocity ; Coronary Angiography ; Coronary Artery Disease/diagnosis/physiopathology/*therapy ; *Coronary Circulation ; Coronary Vessels/*physiopathology/radiography ; Drug-Eluting Stents ; *Endothelial Progenitor Cells/radiography ; Female ; Humans ; Male ; Microvessels/*physiopathology/radiography ; Middle Aged ; Percutaneous Coronary Intervention/*instrumentation ; Prosthesis Design ; *Re-Epithelialization ; *Stents ; Time Factors ; Treatment Outcome ; Vascular Resistance