Left Anterior Oblique Position Research Articles

Analysis and consideration of radiation dose distribution in cardiac catheterization interventions

objective: To assess the variations in radiation dose at different areas in the cardiac catheterization room during cardiac catheterization interventions. methods:To simulate the conventional operation in cardiac catheterization interventions, perform angiography on standard manikins ,the radiation dose was collected from 22 areas in the cardiac catheterization room under 8 projection angles, and each area was repeated 5 times, and the collected data was analyzed using one-way ANOVA and independent sample t-test. results:Analysis of the radiation dose in 22 areas under 8 projection angles revealed that the lowest radiation dose was found in the area at the end of the operating table in the cardiac catheterization room (p < 0.05), and the highest radiation dose was found in the area on the left and right sides of the X-ray tube (p < 0.05); the radiation dose in the area on the right side of the X-ray tube of the DSA machine was greater than that in the conventional standing area of the first operator (p < 0.05)，and the radiation dose in the conventional standing area of the second operator was greater than that in the conventional standing area of the first operator (p < 0.05); the radiation dose in the standing area of the first operator was highest in the cephalic position (CRA 30°) (p < 0.05), and the radiation dose in the standing area of the second operator was highest in the left anterior oblique position (LAO 45°) (p < 0.05); in the angle of RAO projection, the radiation dose in the right area of the X-ray tube was greater than that in the left area of the X-ray tube (p < 0.05). Under the RAO projection angle, the radiation dose from the right side of the X-ray tube of the DSA machine was greater than that from the left side (p<0.05), and the result was reversed at the projection angle of the LAO. conclusion:The radiation dose during cardiac catheterization interventions is lowest in the area at the end of the operating table, which can be used as a standing area for nurses and as an area for the placement of surgical equipment and supplies. At the same time, it is necessary to pay attention to the radiation dose to the second operator and to further improve the radiation protection measures for the second operator, and additional measures are needed to minimize the radiation dose to the operators in the cephalic position (CRA 30°) and in the left anterior oblique position (LAO 45°).

Estimating radiation exposure of the brain of a physician with a protective flap in interventional radiology: A phantom study.

PurposeThe efficiency of protective equipment for the brain has not been verified at the left anterior oblique (LAO) position, which is commonly used in clinical procedures. The purpose of this study was to investigate radiation exposure of the brain in interventional radiology (IR) and the shielding ability of a new protective flap.MethodsWe made a flap that combined a protective cap with a left lateral face shield. The flap was made of tungsten‐containing rubber (TCR). An anthropomorphic head phantom was placed at the physician's position, and air kerma rates (μGy/min and μGy/15s) were measured by electronic dosimeter at three locations: the surface of the left side of the head, and the left and right temporal lobes with the protective cap and the flap in fluoroscopy and cine modes. The X‐ray tube was at the lower left side of the physician, and its angles were LAO60 and LAO60CAU40. The tube voltage (95–125 kV), tube current (4.7–732 mA), and air kerma rate (27.8–1078 mGy/min) were automatically adjusted by the X‐ray system. We obtained the cap and the flap shielding efficiencies.ResultsIn cine mode at LAO60CAU40, the shielding efficiencies on the surface of the left side of the head and left temporal lobe with the cap were 92.6% and 5.1%, respectively, and the corresponding shielding efficiencies with the flap were 92.5% and 86.1%, respectively. The flap can reduce radiation exposure of the brain more than the cap alone.ConclusionsAt the left anterior oblique in interventional radiology, the flap can reduce exposure to the brain.

SPECT-guided myocardial perfusion and metabolic fatty acid planar imaging to assess the severity of the pulmonary hypertension in patients with chronic thromboembolic pulmonary hypertension

Abstract Background Patients with chronic thromboembolic pulmonary hypertension (CTEPH) represent right ventricular (RV) enlargement and hypertrophy, which consequently increase the RV myocardial perfusion. Although the main energy source of myocardium is fatty acid, it remains unknown whether myocardial fatty acid metabolism is altered in loaded RV. Herein, we report a novel approach to assess the RV perfusion and fatty acid metabolism, which is called SPECT-guided planar imaging. Purpose To evaluate if SPECT-guided myocardial perfusion and metabolic fatty acid planar imaging reflects the severity of the pulmonary hypertension in patients with chronic thromboembolic pulmonary hypertension. Methods The study groups included 30 patients with CTEPH and 20 healthy controls. In these patients with CTEPH, 15 patients underwent pulmonary thromboendarterectomy (PEA). Mean pulmonary artery pressure (mPAP) by right heart catheterization was obtained in all CTEPH patients. 201Thallium (201Tl) and iodine-123-beta-methyl iodophenyl pentadecanoic acid (123I-BMIPP) planar myocardial imaging was performed in all participants. For the patients undergoing PEA, repetitive SPECT-guided 201Tl and 123I-BMIPP planar imaging was performed one year after the procedure. To assess the RV overload, the planar images were performed in left anterior oblique position, optimized to separate the RV from the left ventricular (LV) using SPECT-guided transverse imaging. We measured the total counts of 201Tl and 123I-BMIPP in both the RV and LV. Moreover, we calculated their relative counts of the RV to LV (abbreviated as HR/HL (Tl) and HR/HL (BMIPP), respectively) to determine the indices of myocardial perfusion and fatty acid metabolism, respectively. Results Both HR/HL (Tl) and HR/HL (BMIPP) were elevated in the CTEPH patients compared with control (0.62±0.14 vs. 0.36±0.07, p<0.01 and 0.57±0.14 vs. 0.34±0.06, p<0.01, respectively). In the CTEPH patients, average mPAP was 44.0±9.52 mmHg, which was correlated with HR/HL (Tl) (r=0.675, p<0.001) and HR/HL (BMIPP) (r=0.685, p<0.01). Furthermore, the decrease of average mPAP 1 year after PEA was positively associated with the decrease of HR/HL (Tl) (r=0.646, p<0.01) and HR/HL (BMIPP) (r=0.504, p<0.05) 1 year after PEA. Conclusions In patients with CTEPH, RV myocardial perfusion and fatty acid metabolism was upregulated and moderately correlated with mPAP. SPECT-guided 201Tl and 123I-BMIPP planar imaging is a novel and noninvasive imaging modality to assess the severity of PH. Funding Acknowledgement Type of funding sources: None.

Can QRS morphology be used to differentiate between true septal vs. apparently septal lead placement? An analysis of ECG of real mid-septal, apparent mid-septal, and apical pacing.

The location of the pacemaker lead is based on the shape of the lead on fluoroscopy only, typically in the left and right anterior oblique positions. However, these fluoroscopy criteria are insufficient and many leads apparently considered to be in septum are in fact anchored in anterior wall. Periprocedural ECG could determine the correct lead location. The aim of the current analysis is to characterize ECG criteria associated with a correct position of the right ventricular (RV) lead in the mid-septum. Patients with indications for a pacemaker had the RV lead implanted in the apex (Group A) or mid-septum using the standard fluoroscopic criteria. The exact position of the RV lead was verified using computed tomography. Based on the findings, the mid-septal group was divided into two subgroups: (i) true septum, i.e. lead was found in the mid-septum, and (ii) false septum, i.e. lead was in the adjacent areas (anterior wall, anteroseptal groove). Paced ECGs were acquired from all patients and multiple criteria were analysed. Paced ECGs from 106 patients were analysed (27 in A, 36 in true septum, and 43 in false septum group). Group A had a significantly wider QRS, more left-deviated axis and later transition zone compared with the true septum and false septum groups. There were no differences in presence of q in lead I, or notching in inferior or lateral leads between the three groups. QRS patterns of true septum and false septum groups were similar with only one exception of the transition zone. In the multivariate model, the only ECG parameters associated with correct lead placement in the septum was an earlier transition zone (odds ratio (OR) 2.53, P = 0.001). ECGs can be easily used to differentiate apical pacing from septal or septum-close pacing. The only ECG characteristic that could help to identify true septum lead position was the transition zone in the precordial leads. ClinicalTrials.gov identifier: NCT02412176.

Clinical impact of the gap-angle ratio in patients with ostial lesions of the right coronary artery undergoing percutaneous coronary intervention.

The aim of this study was to investigate the incidence of binary restenosis and its predictors in patients with ostial lesions of the right coronary artery (RCAos) who underwent percutaneous coronary intervention (PCI). RCAos are associated with a high incidence of restenosis, and the implantations of drug-eluting stents for RCAos have not been fully elucidated. The study participants included 75 patients (72.3 ± 9.5years, 72% men) who underwent PCI for RCAos at our institution between November 2001 and May 2017. The angle between the greater curvature of the aortic wall and the right coronary artery take-off in the diastolic and systolic phases in the left anterior oblique position view was investigated. Clinical outcome was defined as binary restenosis at follow-up coronary angiography. We also evaluated target lesion failure (TLF) defined as a composite of cardiac mortality, target vessel myocardial infarction, and target lesion revascularization (TLR). The incidence of binary restenosis was 48.0% (n = 36) of the entire cohort. The incidence of TLF was 49.3% (n = 37) of the entire cohort, which was mainly driven by TLR (36.0%, n = 27). The area under the curve of the gap-angle ratio [(difference between the maximum and minimum angles)/(minimum angle); GAR] for binary restenosis was 0.73, and the cutoff value was 0.306 (sensitivity 67%, specificity 82%). The patients were divided into two groups: a low-GAR (< 0.306; n = 30) and high-GAR group (> 0.306; n = 45). Binary restenosis was more frequent in the high-GAR group than in the low-GAR group (76.7% vs. 28.9%, p = 0.007). The cumulative rate of TLF was significantly higher in the high-GAR group when compared with the low-GAR group (53.3% vs. 40.0%, p = 0.01), which was mainly driven by TLR (56.7% vs. 22.2%, p = 0.01). High-GAR (> 0.306) [OR 2.66 (1.34-5.31), p = 0.005] and stent under expansion [OR 2.37 (1.10-5.11), p = 0.03] were found to be independent predictors of binary restenosis after adjustment for multiple confounders. Multivariable analysis also revealed that high-GAR (> 0.306) [OR 2.06 (1.02-4.14), p = 0.03] and stent under expansion [OR 2.82 (1.28-6.19), p = 0.01] were independent predictors of TLF. We suggest that GAR (> 0.306) predicts binary restenosis and TLF in patients undergoing PCI for RCAos.

Abstract 12534: Clinical Impact of Gap Angle Ratio in Patient With Ostial Lesion of Right Coronary Artery Undergoing Percutaneous Coronary Intervention

Background: However in drug-eluting stent (DES) era, ostial lesion of right coronary artery (RCA) is associated with high incidence of in-stent restenosis (ISR). And the issue of DES implantation in ostial lesion of RCA has not been adequately evaluated. Objective: The purpose of this study is to investigate the incidence of ISR and the predictive value in patients with ostial lesion of RCA who underwent percutaneous coronary intervention (PCI). Methods: A cohort of 56 patients (73.4±9.9 years-old, 70% male) who underwent PCI for ostial lesion of RCA was retrospectively analyzed in Tokyo Metropolitan Bokutoh hospital from November 2001 to October 2015. We investigated the angle between greater curvature of aortic wall and RCA take-off at diastolic and systolic phase in left anterior oblique (LAO) position view. Clinical outcome was defined as ISR at follow up coronary angiography. We performed receiver operating characteristic analysis for ISR. Results: Incidence of ISR was 41.1% (n=23) in entire patients. Area under the curve of Gap (angle difference between maximum and minimum) / minimum Angle Ratio (GAR-min) for ISR was 0.723 and the cut off value was 0.306 (specificity 0.818, sensitivity 0.696). We divided patients into 2 group; Low GAR group (&lt;0.306: n=35); High GAR group (≥0.306: n=21). There were no significant differences between 2 groups in baseline characteristics. ISR was significantly lower incidence in Low GAR compared with High GAR (22.9% vs. 71.4%, p&lt;0.001). GAR&gt;0.306 was an independent predictor of ISR after adjustment of multiple cofounders (OR: 8.54, 95% CI: 2.18-33.1, p=0.002). Conclusion: These data suggest that High GAR (≥0.306) may predict ISR in patient undergoing PCI to ostial lesion of RCA.

Coronary angiograms in left anterior oblique position showing the initial result after complex retrograde CTO-PCI with a patent RCA with regular TIMI 3 flow and the helical-shaped neoluminal right coronary artery as a result of "spiral stenting"

Coronary angiograms in left anterior oblique position showing the initial result after complex retrograde CTO-PCI with a patent RCA with regular TIMI 3 flow and the helical-shaped neoluminal right coronary artery as a result of "spiral stenting"

Editor's Choice – Angulation of the C-Arm During Complex Endovascular Aortic Procedures Increases Radiation Exposure to the Head

The increased complexity of endovascular aortic repair necessitates longer procedural time and higher radiation exposure to the operator, particularly to exposed body parts. The aims were to measure directly exposure to radiation of the bodies and heads of the operating team during endovascular repair of thoracoabdominal aortic aneurysms (TAAA), and to identify factors that may increase exposure. This was a single-centre prospective study. Between October 2013 and July 2014, consecutive elective branched and fenestrated TAAA repairs performed in a hybrid operating room were studied. Electronic dosimeters were used to measure directly radiation exposure to the primary (PO) and assistant (AO) operator in three different areas (under-lead, over-lead, and head). Fluoroscopy and digital subtraction angiography (DSA) acquisition times, C-arm angulation, and PO/AO height were recorded. Seventeen cases were analysed (Crawford II-IV), with a median operating time of 280minutes (interquartile range 200-330minutes). Median age was 76 years (range 71-81 years); median body mass index was 28kg/m(2) (25-32kg/m(2)). Stent-grafts incorporated branches only, fenestrations only, or a mixture of branches and fenestrations. A total of 21 branches and 38 fenestrations were cannulated and stented. Head dose was significantly higher in the PO compared with the AO (median 54μSv [range 24-130μSv] vs. 15μSv [range 7-43μSv], respectively; p=.022), as was over-lead body dose (median 80μSv [range 37-163μSv] vs. 32μSv [range 6-48μSv], respectively; p=.003). Corresponding under-lead doses were similar between operators (median 4μSv [range 1-17μSv] vs. 1μSv [range 1-3μSv], respectively; p=.222). Primary operator height, DSA acquisition time in left anterior oblique (LAO) position, and degrees of LAO angulation were independent predictors of PO head dose (p<.05). The head is an unprotected area receiving a significant radiation dose during complex endovascular aortic repair. The deleterious effects of exposure to this area are not fully understood. Vascular interventionalists should be cognisant of head exposure increasing with C-arm angulation, and limit this manoeuvre.

Geometric changes of the inferior vena cava in trauma patients subjected to volume resuscitation.

Dynamic changes in anatomic geometry of the inferior vena cava from changes in intravascular volume may cause passive stresses on inferior vena cava filters. In this study, we aim to quantify variability in inferior vena cava dimensions and anatomic orientation to determine how intravascular volume changes may impact complications of inferior vena cava filter placement, such as migration, tilting, perforation, and thrombosis. Retrospective computed tomography measurements of major axis, minor axis, and horizontal diameters of the inferior vena cava at 1 and 5 cm below the lowest renal vein in 58 adult trauma patients in pre-resuscitative (hypovolemic) and post-resuscitative (euvolemic) states were assessed in a blinded fashion by two independent readers. Inferior vena cava perimeter, area, and volume were calculated and correlated with caval orientation. Mean volumes of the inferior vena cava segment on pre- and post-resuscitation scans were 9.0 cm(3) and 11.0 cm(3), respectively, with mean percentage increase of 48.6% (P < 0.001). At 1 cm and 5 cm below the lowest renal vein, the inferior vena cava expanded anisotropically, with the minor axis expanding by an average of 48.7% (P < 0.001) and 30.0% (P = 0.01), respectively, while the major axis changed by only 4.2% (P = 0.11) and 6.6% (P = 0.017), respectively. Cross-sectional area and perimeter at 1 cm below the lowest renal vein expanded by 61.6% (P < 0.001) and 10.7% (P < 0.01), respectively. At 5 cm below the lowest renal vein, the expansion of cross-sectional area and perimeter were 43.9% (P < 0.01) and 10.7% (P = 0.002), respectively. The major axis of the inferior vena cava was oriented in a left-anterior oblique position in all patients, averaging 20° from the horizontal plane. There was significant underestimation of inferior vena cava maximal diameter by horizontal measurement. In pre-resuscitation scans, at 1 cm and 5 cm below the lowest renal vein, the discrepancy between the horizontal and major axis diameter was 2.1 ± 1.2 mm (P < 0.001) and 1.7 ± 1.0 mm (P < 0.001), respectively, while post-resuscitation studies showed the same underestimation at 1 cm and 5 cm below the lowest renal vein to be 2.2 ± 1.2 mm (P < 0.01) and 1.9 ± 1.0 mm (P < 0.01), respectively. There is significant anisotropic variability of infrarenal inferior vena cava geometry with significantly greater expansive and compressive forces in the minor axis. There can be significant volumetric changes in the inferior vena cava with associated perimeter changes but the major axis left-anterior oblique caval configuration is always maintained. These significant dynamic forces may impact inferior vena cava filter stability after implantation. The consistent major axis left-anterior oblique obliquity may lead to underestimation of the inferior vena cava diameter used in standard anteroposterior venography, which may influence initial filter selection.

Origem das artérias dos nós sinoatrial e atrioventricular em população do sul da Índia: um estudo angiográfico

To study the arterial supply of the conducting system and its correlation with the dominance of the coronary arteries in the South Indian population.To determine angiographically the origins of the sinoatrial nodal artery (SAna) and atrioventricular nodal artery (AVna) in Indians.The study included 300 consecutive patients (114 females, 186 males; mean age, 55 years) living in the southern coastal region of India, who underwent coronary angiography either for the symptoms of chest pain, angina pectoris or positive Treadmill Test. The angiograms contained both coronary arteries (right and left) in the right and left anterior oblique position. The origin of SAna and AVna from the coronary arteries was observed and correlated with the arterial dominance.The SA (sinoatrial) node was supplied by the right coronary artery (RCA) in 53% of the cases, by the circumflex (Cx) branch of left coronary artery (LCA) in 42.66%, and by both coronary arteries in 4.33% of cases. The AV (atrioventricular) node was also more often supplied by the RCA (72.33% of cases) than by the Cx branch of the LCA (27.66%), and surprisingly in none of the cases was this node supplied by both coronary arteries.The results of the present study may help cardiac surgeons, particularly in surgeries related to certain valvular disorders, due to the proximity of the nodal branches to the valve complex.

Preoperative Dual-Phase Parathyroid Imaging With Tc-99m-Sestamibi

Previously, we have found that the additional use of a pinhole collimator in parathyroid scintigraphy resulted in a decrease in the number of incorrect side localizations and an increase in reproducibility compared with that of using a parallel-hole collimator alone. The aim was to investigate whether the addition of anterior oblique views to parathyroid scintigraphy (PS) with a pinhole collimator could further enhance the diagnostic ability and reproducibility. The level of preoperative parathyroid hormone (PTH) as a potential predictor of the usefulness of the supplementary views was also studied. Forty-seven patients with primary hyperparathyroidism (HPT) underwent dual-phase PS using a combined protocol with parallel-hole and pinhole collimators. The pinhole collimator was used in the anterior as well as right and left anterior oblique positions. Thyroid pertechnetate scans were undertaken in the same positions. Two observers assessed the images independently. By adding oblique views, the gain in correct side localization occurred in all cases but one was seen in patients with rapid washout. The level of PTH could not predict these patients. The observer agreement on correct side localizations rose significantly from 81% to 94%. The addition of oblique views to the imaging protocol using the pinhole collimator for parathyroid and thyroid scintigraphy in primary HPT results in an increase in observer agreement and the number of correct side localizations in patients with rapid washout of MIBI. The preoperative level of PTH cannot, however, predict these patients.

Usefulness of rotational spin for coronary angiography in patients with advanced renal insufficiency

Coronary angiography in patients with advanced renal insufficiency is typically restricted to cases of life-threatening circumstances such as acute myocardial infarction and unstable angina. To gather a large amount of visual information with a minimum number of cine runs, and consequently, with a minimum volume of contrast medium, we rotated the gantry at 40°/s throughout an angle of 120°, from the right toward the left anterior oblique positions. This technique of rotational spin during cinegraphic runs has not yet become established in invasive cardiology. Three experienced cardiologists independently evaluated all coronary segments in rotational versus standard coronary angiography modes for 15 patients, on the basis of an 11-point scale (0 = cardiac spin far better to 10 = standard mode far better). A score of 5 signified that there was no difference in quality between the 2 modes. The arithmetic mean of the assessment values was 4.9 ± 0.3 for coronary segments, 5.4 ± 1.3 for coronary lesions, 5.1 ± 1.4 for bifurcations, and 5.0 ± 0.1 for coronary flow. The arithmetic means for the volume of contrast medium (25 ± 4 ml), for the overall dose area product (8.6 ± 4.5 Gy × cm 2), and for the number of cine graphic frames (203 ± 65) for a diagnostic cardiac spin were significantly below published typical values in standard mode. Cardiac spin enables 3-dimensional coronary impression under conditions of adequate image quality and represents a new, useful, and beneficial method in invasive cardiology for applications involving the special indication of advanced renal insufficiency.

Giant pseudoaneurysm of the left ventricle diagnosed by radionuclide ventriculography.

A 65-year-old woman was hospitalized with an anterior wall myocardial infarction, complicated with congestive heart failure. Three months later, she was rehospitalized with acute pulmonary edema and a new apical holosystolic murmur. Radionuclide ventriculography in the left anterior oblique position showed a giant pseudoaneurysm of the left ventricle that was verified on echocardiography. The patient was transferred to the cardiosurgery center, and a successful aneurysmectomy was performed.

Non-invasive assessment of technetium-99m albumin transit time distribution in the pulmonary circulation by first-pass angiocardiography.

This study describes a non-invasive method for assessment of the lung transit time distribution of a tracer, using first-pass technetium-99m albumin angiocardiography and a model-free method of deconvolution. Ten patients received a first injection of 1 MBq kg-1 in the external jugular vein to position a gamma camera in the left anterior oblique position and two additional injections (5 MBq kg-1) to record first-pass angiocardiographic data. Right and left ventricular time-activity curves were derived from regions of interest every 0.5 s over a 1-min period. The left ventricular curve was deconvoluted by the right ventricular curve to obtain the lung transport function. The deconvolution procedure was based on a modified version of the Kalman filtering technique. The procedure was repeated at an interval of 30 min in eight patients. Two patients were re-examined up to 2 years later. Skewness, kurtosis and relative dispersion of the distributions did not change over time. We also found that the distribution, once normalized by its first moment, was independent of isolated changes in heart rate or cardiac output. Comparison of curve shapes at an interval of 30 min by point by point analysis demonstrated the reproducibility of the technique. We conclude that computation of the pulmonary transit time distribution of 99mTc-albumin from a standard angiocardiography procedure by model-free deconvolution is reliable and reproducible over time. We suggest that it may be a valuable tool for the non-invasive follow-up of the pulmonary circulation.

Influence of meal energy on gastric emptying in healthy Chinese.

Radionuclide gastric emptying studies of liquid phases were used to evaluate the gastric motility of healthy Chinese. A total of 53 normal volunteers were included in this study and divided into two groups. Group 1, included 20 males and 8 females (ages: 17-73) who received a meal which consisted of 500ml normal saline containing 500 uCi of Tc-99m phytate. Group 2, included 19 males and 6 females (ages: 27-73) who received a meal which consisted of 500ml 5% glucose solution (25g glucose, 100Kcal) labeled with 500 uCi Tc-99m phytate. Studies were performed with the subjects in the supine position and a gamma camera in a left anterior oblique (LAO) position, while data were collected for 30 minutes after injection of the liquid meal. The gastric emptying time was presented as the half-time (T1/2) for the food to empty from the stomach. The study results showed that the T1/2 was 20.5 +/- 7.2 min in Group 1 and 35.3 +/- 11.7 min in Group 2. We conclude that gastric emptying is slower for a liquid meal with a higher caloric content.

Influence of Age on Gastric Emptying in Healthy Chinese

Radionuclide gastric emptying studies, including solid and liquid phases, were used to evaluate the gastric motility of healthy Chinese. Forty-eight patients (18-76 years old) and 38 volunteers (27-79 years old) accepted solid or liquid food gastric emptying studies, respectively. The solid meal was two fried eggs mixed with 500 microCi Tc-99m phytate and two pieces of toast to form a sandwich. The liquid meal was 500 ml of water with 5% glucose and 500 microCi Tc-99m phytate. Studies were performed with the subjects in the supine position and a gamma camera in a left anterior oblique (LAO) position while data were collected for 90 minutes and 30 minutes after finishing the solid and liquid meal, respectively. The gastric emptying time was presented as a half-time (t1/2) of the food emptying from the stomach. The study results showed that the t1/2 is 89.0 +/- 17.8 in older patients (> 60 years old) and 88.0 +/- 18.2 in younger patients (< or = 60 years old) for the solid phase studies (P > 0.05), and that the t1/2 is 46.2 +/- 11.1 in older patients (> 60 years old) and 31.9 +/- 11.3 in younger patients (< or = 60 years old) for the liquid phase studies (P < 0.05). We concluded that the age effects of gastric emptying in healthy Chinese occurred only in the liquid phase.

Cholelithasis

Extracorporeal shock wave lithotripsy (ESWL) is one nonsurgical method available to treat cholelithiasis. Optimal imaging of gallstones is crucial in assessment and treatment using ESWL. The purpose of this study was to see if placing the patient in the left anterior oblique (prone with the right side elevated) position, rotating the patient 360°, or doing both of these things made it easier to visualize and measure gallstones during ultrasound examination of patients both before and after lithotripsy. There was improvement in stone visualization in 29% of the cases in this study when one or the other of these positions was used.

Human left ventricular wall vibration responded to precordial minute vibration.

We examined, noninvasively, the response of the left ventricular (LV) wall to precordially applied vibration in seven normal subjects. The LV posterobasal wall vibration was detected by an esophageal vibration sensor. Even though the amplitude of input vibration was maintained at a constant level, a sharp change in amplitude of the LV wall vibration was observed during the cardiac cycle, especially when 1) the subject was lying in a 45 degree left anterior oblique supine position, 2) the sensor was positioned at approx. 40 cm from the incisor teeth and 3) breath was at expiration. The pattern of this amplitude modulation changed with the input frequency. We concluded that the change in amplitude of output signal must have resulted from LV contraction and relaxation.

Quantification of valvular regurgitation using radioisotopes

Mitral and aortic regurgitations impose an abnormal volume overload on the left ventricle. Recent advances in radionuclide angiographic measurements of all cardiac volumes have made this a practical technique for the detection, quantification and functional assessment of valvular regurgitations and shunts. The method is based on the comparative evaluation of total and effective left ventricular stroke volume. In the radionuclide technique, the right ventricular stroke volume is most frequently used to represent the effective left ventricular stroke volume although techniques have been presented which used as reference the left ventricular stroke volume calculated from measurements of heart rate and cardiac output (Fick method or dye dilution or scintigraphic techniques). The technique can be performed either during first-pass or at equilibrium. Equilibrium measurements are performed in the left anterior oblique position. The stroke volume ratio and the regurgitant fraction are calculated. This technique has been shown to provide adequate quantitative measurements of mitral and aortic regurgitations. Its specificity is adequate with careful positioning and if regions of interest are determined and care is taken to exclude inadequate studies (as these can be prospectively recognized). The technique can separate moderate from severe regurgitation, provide follow-up values for both left ventricular volume and regurgitant fraction, and assess the effect of interventions on the amount of regurgitation. The technique is, however, not adequate to detect mild or minimal regurgitation. In conclusion, equilibrium scintigraphic measurement of valvular regurgitation is an attractive new technique for measuring valvular regurgitation. Its clinical value lies in its simplicity, its reproducibility and its wide applicability. Its accuracy will be improved by performance of gated tomographic acquisitions.

Effects of the Mueller maneuver on global and regional left ventricular function in angina pectoris with or without previous myocardial infarction

In patients with coronary artery disease, left ventricular (LV) regional wall akinesia can develop during the Mueller maneuver. 15 The present study determines if the presence of myocardial ischemic disease with no infarction is a sufficient condition for this to occur, or if the presence of prior acute myocardial infarction (MI) is necessary. In men, first-pass radionuclide ventriculography was performed in the 30 ° left anterior oblique supine position to measure LV ejection fraction, end-diastolic and end-systolic volumes and heart rate, and to obtain an image of the LV cavitary perimeter. This procedure was performed in 4 subject groups: 13 normal volunteers, 25 patients with coronary artery disease but no prior MI, 13 patients with coronary artery disease and prior nontransmural MI, and 36 patients with coronary artery disease and prior transmural MI. All patients had angina and underwent routine contrast coronary angiography; 60 also underwent contrast LV angiography. Ejection fraction decreased during the Mueller maneuver in each of all the coronary artery disease groups (p < 0.01), but not in the normal subjects. Heart rate increased in groups 1, 2 and 4 (p < 0.01), and end-diastolic volume decreased in all 4 groups (p < 0.01), whereas end-systolic volume did not change. Only in group 4 did regional wall akinesia develop (17 patients) during the Mueller maneuver. Among patients who had akinesia during the Mueller maneuver and also underwent routine contrast ventriculography, half of the akinetic segments were not seen on routine contrast study, but were seen only on radionuclide ventriculography during the Mueller maneuver. Thus, the appearance of regional LV wall akinesia on the radionuclide ventriculogram during the Mueller maneuver signifies the presence of prior transmural MI. The Mueller maneuver enhances the sensitivity of the radionuclide ventriculogram for detecting poorly functioning or nonfunctioning myocardium. The decrease in ejection fraction occurring in the patient groups, even in the absence of prior MI, may indicate that subtle abnormalities are present, which are exaggerated and detected during the performance of the Mueller maneuver.