Evaluation of patient radiation dose during cardiac interventional procedures: what is the most effective method?

Cardiac interventional radiology has lower risks than surgical procedures. This is despite the fact that radiation doses from cardiac intervention procedures are the highest of any commonly performed general X-ray examination. Maximum radiation skin doses (MSDs) should be determined to avoid radiation-associated skin injuries in patients undergoing cardiac intervention procedures. However, real-time evaluation of MSD is unavailable for many cardiac intervention procedures. This review describes methods of determining MSD during cardiac intervention procedures. Currently, in most cardiac intervention procedures, real-time measuring of MSD is not feasible. Thus, we recommend that physicians record the patient's total entrance skin dose, such as the dose at the interventional reference point when it can be monitored, in order to estimate MSD in intervention procedures.

Effect of radiation monitoring method and formula differences on estimated physician dose during percutaneous coronary intervention.

BACKGROUND: Currently, one or two dosimeters are used to monitor radiation exposure in most cardiac laboratories. In addition, several different formulas are used to convert exposure data into an effective dose (ED). PURPOSE: To clarify the effect of monitoring methods and formula selection on the estimated ED for physicians during percutaneous coronary interventions (PCIs). MATERIAL AND METHODS: The ED of physicians during cardiac catheterization was determined using an optically stimulated luminescence dosimeter (Luxel badge). Two Luxel badges were worn: one beneath a personal lead apron (0.35-mm lead equivalent) at the chest and one outside of the apron at the neck. RESULTS: The difference in the average ED of seven physicians was approximately fivefold (range 1.13-5.43 mSv/year) using the six different formulas in the clinical evaluation. The estimated physician ED differed markedly according to both the monitoring method and formula selected. CONCLUSION: ED estimation is dependent on both the monitoring method and the formula used. Therefore, it is important that comparisons among laboratories are based on the same monitoring method and same formula for calculating the ED.

A PHANTOM STUDY TO DETERMINE THE OPTIMAL PLACEMENT OF EYE DOSEMETERS ON INTERVENTIONAL CARDIOLOGY STAFF.

The International Commission on Radiological Protection has substantially reduced the recommended maximum annual eye lens dose for workers. Use of a dedicated eye dosemeter is one method for accurate dose monitoring. The main aim of this study was to yield recommendations for optimal placement of eye dosemeters to estimate the eye dose to interventional cardiology physicians and nurses. A phantom measurement was conducted to simulate typical interventional cardiology procedures. Considering eight X-ray tube angulations, the left side of the head position provide good estimates for physician, and the forehead position provide good estimates for nurse.

Influence of the target vessel on the location and area of maximum skin dose during percutaneous coronary intervention.

BACKGROUND: A number of cases involving radiation-associated patient skin injury attributable to percutaneous coronary intervention (PCI) have been reported. Knowledge of the location and area of the patient's maximum skin dose (MSD) in PCI is necessary to reduce the risk of skin injury. PURPOSE: To determine the location and area of the MSD in PCI, and separately analyze the effects of different target vessels. MATERIAL AND METHODS: 197 consecutive PCI procedures were studied, and the location and area of the MSD were calculated by a skin-dose mapping software program: Caregraph. The target vessels of the PCI procedures were divided into four groups based on the American Heart Association (AHA) classification. RESULTS: The sites of the MSD for AHA #1-3, AHA #4, and AHA #11-15 were located mainly on the right back skin, the lower right or center back skin, and the upper back skin areas, respectively, whereas the MSD sites for the AHA #5-10 PCI were widely spread. The MSD area for the AHA #4 PCI was larger than that for the AHA #11-15 PCI (P<0.0001). CONCLUSION: Although the radiation associated with PCI can be widely spread and variable, we observed a tendency regarding the location and area of the MSD when we separately analyzed the data for different target vessels. We recommend the use of a smaller radiation field size and the elimination of overlapping fields during PCI.

Coronary angioplasty ameliorates hypoperfusion-induced endothelial dysfunction in patients with stable angina pectoris.

OBJECTIVES: This study sought to investigate the effect of coronary angioplasty on chronic hypoperfusion-induced endothelial dysfunction in patients with coronary heart disease. BACKGROUND: The endothelium is an important component for organ flow regulation. Ischemia with or without reperfusion is known to cause endothelial dysfunction. We tested the hypothesis that chronic hypoperfusion impairs endothelial function in the angiographically normal coronary artery segment distal to stenosis and that the impairment by chronic hypoperfusion is reduced by coronary angioplasty. METHODS: In 13 patients with stable angina pectoris, substance P (10, 30 and 100 pmol) and nitroglycerin (200 micrograms) were sequentially infused into the coronary artery in a cumulative manner on the day after coronary angioplasty. In 10 of these patients, vascular responses to these agents were again investigated 3 months after angioplasty. Changes in vascular diameter were evaluated in vessels located proximal and distal to the target lesion, both of which were angiographically normal, by performing computer-assisted quantitative coronary angiography. In five patients, the transstenotic pressure gradient was also measured with a pressure sensor-mounted guide wire before angioplasty. RESULTS: On the day after angioplasty, the magnitude of dilation by substance P in distal segments was significantly less than that in proximal segments and inversely correlated with the transstenotic pressure gradient (p < 0.05) and lesion stenosis (p < 0.05). There was no difference in nitroglycerin-induced vasodilation between the two vessel segment groups. Three months later, the impaired response to substance P in the distal segment was restored to normal. CONCLUSIONS: We conclude that chronic hypoperfusion impairs endothelium-dependent dilation of coronary artery distal to critical stenosis in patients with ischemic heart disease and that coronary angioplasty ameliorates the endothelial dysfunction within 3 months.

Stent angioplasty for renovascular disease associated with acute aortic dissection.

Aortic replacement was performed in a patient with acute type A aortic dissection originating from the descending thoracic aorta. Postoperatively, a persistent false lumen resulted in severe stenosis of the right renal artery. Percutaneous stent angioplasty improved renovascular hypertension and renal function. This procedure is useful for management of patients with branch complications of aortic dissection.

Cine viewing of abdominal CT.

A few studies have been reported that CT cine viewing on the CRT is superior to film-based viewing of CT images (Seltzer et al., Radiology 197 (1994) 119; Bonaldi et al., Am. J. Roentgenol. 170 (1998) 373; Tillich et al., Am. J. Roentgenol. 169 (1997) 1611). The purpose of our study is to know how to use cine viewing of abdominal CT. Thirty CT studies on the abdomen with both precontrast and postcontrast images were examined. The suitable rate of cine viewing ranged from 1 to 6 frames per second according to the size, the contrast and the complexity of the anatomical structures, and the slice thickness. For small or complex structures, checking each image might be required to know the full detail of them. Positional sorting among multiphase images, which is followed by consecutive display of a precontrast image, postcontrast early and late phase images at one position and so on, is useful to see the dynamic pattern of enhancement of the anatomical structures. However, there was no significant difference between cine viewing and film-based viewing concerning both the detectability of the anatomical structures and the conspicuity of enhancement of the liver and the pancreas, so that cine viewing might be an alternative to film-based viewing for CT diagnosis of the abdomen.

Bronchial artery aneurysm treated with percutaneous transluminal coil embolization.

We present a case with asymptomatic mediastinal bronchial artery aneurysm at the origin of the left bronchial artery. This bronchial artery aneurysm was successfully treated with percutaneous transluminal coil embolization. Complete embolization of the feeding artery and tributaries from the aneurysm is the key to successful isolation of a large bronchial artery aneurysm from the circulation. Percutaneous transluminal embolization is one of the treatment options for a patient with asymptomatic, incidentally-identified bronchial artery aneurysm.

[Percutaneous transcatheter coil embolization of the patent ductus arteriosus for elderly patient with left ventricular disfunction].

We performed the coil embolization for 64-year-old male with patent ductus arteriosus and left ventricular dysfunction. We used "snare method" and "cross catheter technique" delivering one coil transvenously and one coil transarterially. Echocardiograms at 7 month after the procedure demonstrated complete occlusion of the ductus, though small shunt was detected at discharge.

[Acquired pulmonary stenosis caused by mediastinal mature teratoma: a case report].

A 13-year-old girl was admitted with a sudden onset of chest oppression. Mediastinal teratoma was suspected on chest X-ray and CT scan. A grade 2/6 systolic murmur was heard at the upper left sternal area and cardiac catheterization showed mild pulmonary stenosis. After resection of the tumor, the murmur disappeared and histopathological diagnosis was mature teratoma. This is a rare case report of pulmonary stenosis caused by mediastinal mature teratoma.

FFT analysis of the X-ray tube voltage waveforms of high-frequency generators for radiographic systems.

PURPOSE: To present a novel method for analyzing the voltage waveform from high-frequency X-ray generators for radiographic systems. MATERIAL AND METHODS: The output signal of the actual voltage across the tube of a high-frequency generator was measured using the built-in voltage sense taps that are used for voltage regulation feedback in X-ray generators. The output signal was stored in an analyzing recorder, and the waveforms were analyzed using FFT analysis. The FFT analysis of high-frequency generators consisted of obtaining the power spectrum, comparing the major frequency components in the tube voltage waveforms, and examining the intensity of each frequency component. RESULTS: FFT analysis enables an objective comparison of the complex tube voltage waveforms in high-frequency X-ray generators. FFT analysis detected the change in the X-ray tube voltage waveform that occurred when there were problems with the high-frequency generator. CONCLUSION: High-frequency X-ray generators are becoming the universal choice for radiographic systems. The X-ray tube voltage and its waveform are important features of an X-ray generator, and quality assurance (QA) is important, too. As a tool for engineers involved in the design and development of X-ray generators, we can see that our methods (FFT analysis) might have some value as a means of describing generator performance under varying conditions. Furthermore, since the X-ray tube voltage waveform of a high-frequency generator is complex, FFT analysis may be useful for QA of the waveform.

Feasibility of rapid-sequence 31P magnetic resonance spectroscopy in cardiac patients.

PURPOSE: To determine the clinical feasibility of rapid-sequence phosphorus-31 magnetic resonance spectroscopy (31P-MRS) of the heart with cardiac patients using a 1.5T clinical MR system. MATERIAL AND METHODS: Twenty cardiac patients, i.e. dilated cardiomyopathy (DCM) 13 cases, hypertrophic cardiomyopathy (HCM) 3 cases, hypertensive heart diseases (HHD) 3 cases, and aortic regurgitation (AR) 1 case were examined using rapid cardiac 31P-MRS. Complete three-dimensional localization was performed using a two-dimensional phosphorus chemical-shift imaging sequence in combination with 30-mm axial slice-selective excitation. The rapid-sequence 31P-MRS procedure was phase encoded in arrays of 8 x 8 steps with an average of 4 acquisitions. The total examination time, including proton imaging and shimming, for the rapid cardiac 31P-MRS procedure, ranged from 10 to 15 min, depending on the heart rate. Student's t test was used to compare creatine phosphate (PCr)/adenosine triphosphate (ATP) ratios from the cardiac patients with those of the control subjects (n = 13). RESULTS: The myocardial PCr/ATP ratio obtained by rapid 31P-MRS was significantly lower (P < 0.001) in DCM patients (1.82 +/- 0.33, mean +/- SD), and in patients with global myocardial dysfunction (combined data for 20 patients: 1.89 +/- 0.32) than in normal volunteers (2.96 +/- 0.59). These results are similar to previous studies. CONCLUSION: Rapid-sequence 31P-MRS may be a valid diagnostic tool for patients with cardiac disease.

[Improved methods for transseptal left heart catheterization].

Although the transseptal approach is useful for evaluation of reliable hemodynamics, this technique is not used commonly for its invasive procedure. We report a new technique for transseptal left heart catheterization utilizing J-shaped guide wire (0.018 inch). The guide wire is available for protecting the atrial wall from perforation by transseptal needle. Transseptal approach was performed by this technique in 58 patients with aortic valvular disease and mitral stenosis, including 6 cases of percutaneous transluminal mitral commissurotomy. We conclude that the J-shaped guide wire and the new technique make transseptal approach a safe and reliable procedure for even inexperienced hands.

[Right ventricular endomyocardial biopsy from the femoral vein].

Several methods are used for percutaneous right ventricular endomyocardial biopsy, including the subclavian venous approach, internal jugular venous approach and femoral venous approach. The femoral venous approach is the most suitable for routine cardiac catheterization, but the risk of right bundle branch block may be increased because the specimens often must be taken from a high position in the right ventricle. We modified the femoral venous approach using King's biotome, and obtained adequate tissue specimens in 14 cases without any complications. We reformed the tip of the biotome into an inverted S shape by scrubbing with the thumb, and we reformed the tip of the long sheath (Cordis) into a J shape by warming with steam, for easy introduction of the biotome and safe biopsy. We describe here the methodological details of our technique.