Radiation safety in the cardiac catheterization laboratory.

Over the years, permissible radiation exposure of operators working with x-ray equipment has become progressively reduced. The number of cardiac catheterizations and related interventional procedures has increased and the procedures have become more prolonged. The patient receives relatively infrequent primary radiation while the operator receives frequent but mainly secondary radiation. The operator uses protective barriers, correct positioning of the patient and careful techniques to reduce radiation exposure. The effects of radiation are cumulative and permanent. They may be stochastic or nonstochastic, and somatic and/or genetic, and onset may be delayed for many years. To minimize exposure of patient and operator, cardiologists need a better understanding of radiation physics and of cardiac x-ray equipment. Technical breakthroughs such as digital imaging, pulse fluoroscopy, reduction of frame rates from 60 or 30 frames/s to 15 frames/s, and progression to the filmless laboratory will substantially reduce radiation. This review discusses current cardiac x-ray equipment, possible future developments, radiation, and techniques for reducing radiation and improving safety in the cardiac catheterization laboratory.

Percutaneous coronary laser balloon angioplasty: initial results of a multicenter experience.

A multicenter clinical trial was initiated to test the potential safety and short-term efficacy of a percutaneous coronary application of laser balloon angioplasty, which has been shown experimentally to alleviate the common causes (dissection, recoil, thrombus) of suboptimal luminal results of conventional balloon angioplasty. Fifty-five patients, the majority (62%) of whom had relatively high risk lesions, were treated in 10 centers with a laser balloon that was identical in size (3 x 20 mm) to a balloon used for conventional balloon angioplasty performed on the same lesion immediately before laser balloon angioplasty. One or more neodymium:yttrium aluminum garnet (Nd:YAG) (1,060 nm) laser doses of 250 to 450 J were each delivered over a 20 s duration per exposure. Immediately and 1 day after laser balloon angioplasty no significant adverse effects on the arterial lumen were noted in any patient. By computerized image analysis of cineangiograms initial conventional balloon angioplasty failed to achieve a minimal luminal diameter greater than 1.5 mm in 14 patients (25%), including 3 patients with acute closure. However, after subsequent laser balloon angioplasty, minimal luminal diameter exceeded this value in all patients including this subgroup. Overall, minimal luminal diameter increased from 1.74 +/- 0.46 mm after conventional balloon angioplasty to 2.32 +/- 0.31 mm after laser balloon angioplasty (p less than 0.001) with no change found on 1 day and 1 month follow-up angiograms. Thus, laser balloon angioplasty is a safe, effective procedure for improving luminal dimensions after conventional balloon angioplasty.

Twelve-lead electrocardiogram recording during percutaneous transluminal coronary angioplasty. Analysis of reciprocal changes.

Coronary angioplasty was used as a human model of transient myocardial ischemia to evaluate the electrocardiographic characteristics and significance of "reciprocal" ST-segment depression and T wave changes. Continuous 12-lead ECGs were recorded before and during coronary angioplasty in 20 patients, 19 of whom had single vessel disease. In 12 of 14 patients, LAD occlusion produced ischemic changes (peaked T and/or ST elevation) in L1, AVL and at least two precordial leads. "Reciprocal" changes (ST depression and/or T inversion) were observed in at least two inferior wall leads. One patient had ST depression in V4-V6 with no change in the inferior leads and in the other the only ECG change was inferior ST depression with partial inversion of the T wave. In four of six patients, RCA occlusion produced ischemic changes in at least two inferior wall leads and "reciprocal" changes in L1, AVL and at least two anterior wall leads. In LAD as well as RCA occlusions "reciprocal" changes were characterized by inversion of the T wave or inversion of its ascending limb with or without ST depression. The magnitude of the ischemic changes tended to be proportional to the magnitude of the "reciprocal" changes. Our data suggest that: (1) "Reciprocal" changes are not a specific indicator of distant myocardial ischemia due to multivessel disease; (2) the magnitude of ischemic changes correlates with the magnitude of "reciprocal" changes; (3) "Reciprocal" changes may be the only manifestation of acute myocardial ischemia; and (4) "Reciprocal" changes may be represented by inversion of the T wave without displacement of the ST-segment.

Quantitative arteriographic responses to ergonovine provocation in subjects with atypical chest pain.

To evaluate the nonspecific vasoconstrictor response to intravenous ergonovine, and identify patient-related factors that systematically alter changes in coronary dimensions, 33 subjects (22 women, 11 men), mean age 54 years (range 39 to 70) were studied using a standardized ergonovine provocation test (Stanford protocol). Clinical responses, systemic hemodynamics and electrocardiographic changes were determined, with quantitative arteriography used for sequential measurement of proximal right coronary dimensions. A progressive decrease in proximal right coronary diameter was observed, with average control values and final diameters equaling 3.25 +/- 0.49 and 2.56 +/- 0.49 mm, respectively, thus representing an overall -21.2% change from baseline. No significant differences existed in control dimensions when analyzed with respect to gender (3.20 +/- 0.59 vs 3.40 +/- 0.72 mm, women vs men, difference not significant), although women demonstrated a greater decrease from baseline values (0.80 +/- 0.30 vs 0.50 +/- 0.24 mm, women vs men, p less than 0.05). The presence of minor atherosclerotic disease, as determined by the presence of minor (less than 30% diameter) luminal irregularities within the right coronary artery, failed to alter control dimensions (3.30 +/- 0.48 vs 3.20 +/- 0.51 mm, normal vs atherosclerotic persons, difference not significant), but was associated with more ergonovine-induced coronary vasospasm (0.41 +/- 0.27 vs 0.84 +/- 0.21 mm, normal vs atherosclerotic persons, p less than 0.01). Therefore, sequential intravenous ergonovine maleate infusion resulted in progressive, nonspecific reductions in proximal right coronary artery dimensions in subjects without a history compatible with vasospastic angina. This nonspecific vasoconstrictor effect was accentuated in women and subjects with intimal irregularities suggestive of minor atherosclerotic coronary disease.

Percutaneous transluminal angioplasty of stenotic saphenous vein right coronary bypass grafts utilizing a peripheral balloon dilatation catheter without a guiding catheter.

Effective angioplasty of stenosed saphenous vein coronary bypass grafts may be impossible with the standard-size coronary dilatation catheters because the large diameter of these grafts results in unacceptable balloon-to-vessel ratios. We avoided this problem by using a peripheral arterial dilatation catheter with an inflation diameter of 6 mm and obtained a satisfactory short- and long-term result in two patients in whom previous attempts with the largest coronary dilatation catheter (4 mm) had failed. This technique, which precludes the use of a guiding catheter, is suitable only for right bypass grafts.

Aspirin and dipyridamole in the prevention of restenosis after percutaneous transluminal coronary angioplasty.

To examine the role of antiplatelet therapy in the prevention of arterial restenosis after percutaneous transluminal coronary angioplasty (PTCA), we conducted a randomized, double-blind, placebo-controlled study in 376 patients. The active treatment consisted of an oral aspirin-dipyridamole combination (330 mg-75 mg) given three times daily, beginning 24 hours before PTCA. Eight hours before PTCA, the oral dipyridamole was replaced with intravenous dipyridamole at a dosage of 10 mg per hour for 24 hours, and oral aspirin was continued. Sixteen hours after PTCA, the initial combination was reinstituted. Treatment was continued in patients with a successfully dilated vessel until follow-up angiography four to seven months after PTCA--or earlier, if symptoms dictated. Of 249 patients who underwent follow-up angiography, 37.7 percent of patients receiving the active drug had restenosis in at least one segment, as compared with 38.6 percent of patients taking placebo (P not significant). The number of stenotic segments was virtually the same in the two groups. Among the 376 randomized patients, there were 16 periprocedural Q-wave myocardial infarctions--13 in the placebo group and 3 in the active-drug group (6.9 percent vs. 1.6 percent, P = 0.0113). Although the use of this antiplatelet regimen before and after PTCA did not reduce the six-month rate of restenosis after successful coronary angioplasty, it markedly reduced the incidence of transmural myocardial infarction during or soon after PTCA. Thus, the short-term use of antiplatelet agents in relation to PTCA can be recommended.

The use of dextran-40 during percutaneous transluminal coronary angioplasty: a report of three cases of anaphylactoid reactions--one near fatal.

Successful percutaneous transluminal coronary angioplasty is achieved by fracture of the atheromatous plaque and perhaps dilatation of the arterial walls to increase the luminal diameter of the artery. Because this "controlled" injury stimulates platelet adhesion on the subendothelial matrix, the use of dextran-40 in addition to heparin has been advocated. The overall incidence of Dextran-induced anaphylactoid reactions at our institution was 0.6% and of severe life-threatening reactions, 0.2%. With the recent doubts cast on the efficacy of dextran-40, the question arises regarding its routine use in PTCA.

Percutaneous transluminal angioplasty of an anomalous left circumflex coronary artery arising from the right sinus of Valsalva.

This case report describes a patient with isolated stenosis of an anomalous circumflex artery with evidence of left ventricular lateral wall ischaemia. Percutaneous dilatation of this vessel was successfully performed and was facilitated by removing the tip of a standard guiding catheter permitting selective cannulation of the anomalous ostium. Similar innovations in the standard angioplasty technique may permit its application in other unusual anatomical situations.

Transvascular removal of catheter fragments from the great vessels and heart.

Embolization of catheter fragments or fractured spring guidewires used during cardiac catheterization or fractured central venous pressure (CVP) lines is not uncommon. Although CVP lines are usually used in seriously ill patients, often with complications secondary to prior surgical intervention, if the catheter fragments are not removed they can give rise to serious illness or death in about 50% of patients. Experience with the removal of nine such catheter fragments is reported. In eight patients a helical basket was available for removal through a Dotter retrieval catheter. With prolonged hyperalimentation therapy polyethylene catherters become very brittle. They are relatively easy to grip with the wire basket. Silicone elastomer catheters remain pliable but are so bouncy that they are difficult to grip. For removal of catheter fragments from vessels of small diameter, such as the subclavian vein, or vessels in which the catheter has to take an acute bend to enter, such as the right or left pulmonary artery, a smaller, more pliable Bean-Smith-Mahorner biliary stone helical basket was adapted by extending the length of wire to 100 cm. For removal of catheter fragments from the right pulmonary artery it is probably better to use a softer, 100-cm-long no. 8 French right heart catheter. A Dotter retriever catheter set with both large and small helical wire baskets should be available in any cardiac catheterization laboratory.

Better visualization of the asymmetric lesion in coronary arteriography utilizing cranial and caudal angulated projections.

For optimum accuracy, coronary arterial lesions should be visualized as perpendicularly and circumferentially as possible to the course of the affected segments. In the presence of left ventricular enlargement or a heart lying transversely within the chest, the proximal left coronary artery and its two major branches, as well as the distal right coronary artery, show foreshortening or overlap in the standard transverse oblique projections, leading to serious underestimation of the degree of disease present. If the lesions are also asymmetric, then the underestimation will be further enhanced unless the vessel is viewed with added transverse axial projections obtained when an image-intensifier system mounted with a C-arm or U-arm is used.

Specification of angulated projections in coronary arteriography.

In coronary arteriography cranial and caudal angulations are combined with oblique angulations to obtain additional views. The angulations are obtained with a variety of equipment rotating about different axes. The planes and axes in and about which the patient and equipment rotate are defined and the equipment is grouped according to the axes about which it rotates. It is shown that a simple definition of the angulation of a projection may be obtained using concepts and terminology consistent with current radiological practice. One group of equipment then gives directly from the rotation of its component parts the angles specifying the projection. For other equipment, the angles specifying the projection are calculated and tabulated for angles of rotation of the equipment from 0 to 90 degrees. Thus, equivalent projections for the different equipment may be found and compared.

Aortocoronary bypass made possible by coronary endarterectomy.

Thirty bypass grafts to coronary arteries were made possible by manual core endarterectomy. The overall patency rate of the grafts was 57%, which is less than the patency rate of bypass grafts to nonendarterectomized vessels (75 to 80%). In the perioperative period and during follow-up to 29 months there was no increase in mortality or morbidity even when the endarterectomized vessel subsequently became occluded. These results represent early technical experience. Routine anticoagulant therapy in the postoperative period, to prevent early occlusion, was not used. The results of this and other studies suggest that coronary endarterectomy with bypass grafting is a useful procedure in situations where the coronary artery is so severely obstructed that standard saphenous vein bypass grafting cannot be performed; the procedure is superior to coronary endarterectomy alone.

Improved diagnosis in coronary cinearteriography with routine use of 110 degrees oblique views and cranial and caudal angulations. Comparison with standard transverse oblique views in 100 patients.

Conventionally mounted X-ray systems for coronary cinearteriography limit angulation of the X-ray beam to the transverse plane of the patient, and use of the motorized cradle restricts rotation to 60 degrees to 70 degrees. These limitations of available projections seriously hamper adequate examination of the coronary arteries. With use of the Siemen's Cardoskop-U, which was designed to overcome this problem, the coronary arteries of 100 consecutive patients were examined with standard oblique projections, and in addition with cranial and caudal angulated oblique and 110 degrees oblique projections. These arteriograms were independently examined by two expert observers. In approximately 20 percent of patients the additional views unmasked lesions that would otherwise have been missed. In a further 34 percent the diagnosis was significantly improved because the full extent of a lesion was revealed, overlap of branches was avoided or the degree of an eccentric stenosis was upgraded. In 4 of 12 patients with apparently normal arteriograms in standard projections, lesions were unmasked by the additional views.

Saphenous vein bypass grafting. Changes in native circulation and collaterals.

One hundred patients were evaluated 12 to 43 months after saphenous vein bypass surgery. The rate of progression of obstructive disease in the native vessels and changes in collateral circulation were analyzed in detail. Fifty-five per cent of preoperatively patent vessels showed progression proximal to the site of graft insertion, 40% proximal to patent grafts; there was distal progression in only 7% of grafted vessels. The progression rate for nongrafted vessels was 14%. Patent grafts were associated with a high rate of disappearance of collaterals to the grafted vessels, while occluded grafts were associated with preservation of collaterals or appearance of new collaterals. Progression of obstructive disease in the native circulation and changes in collaterals did not prevent symptomatic improvement (93% of patients were symptomatically improved).