Changes in myocardial repolarization in patients undergoing balloon valvuloplasty for congenital pulmonary stenosis: evidence for contraction-excitation feedback in humans

Alterations in ventricular loading conditions lead to changes in action potential duration and arrhythmias via contraction-excitation feedback; a decrease in load leads to prolongation of repolarization. To determine whether changes in right ventricular load alter ventricular repolarization in man, the corrected QT interval, a measure of overall ventricular repolarization, was measured in 32 patients before and after valvuloplasty for pulmonary stenosis. Right ventricular systolic pressure decreased (82.5 +/- 30.7 to 40.5 +/- 9.5 mm Hg, p less than .001) and the QTc increased concurrently (409.1 +/- 24.3 to 440.7 +/- 28.0 msec, p less than .001) after successful valvuloplasty. The increase in QTc was most marked for those patients with a greater than 30 mm Hg decrease in right ventricular pressure (40.0 +/- 23.3 vs 16.3 +/- 21.3 msec, p = .006). In a subset of seven patients in whom monophasic action potentials were recorded, monophasic action potential duration, a measure of local repolarization, was prolonged (230.0 +/- 24.3 vs 216.9 +/- 21.9, p less than .001) after successful valvuloplasty, confirming that the QTc prolongation reflected changes in local ventricular repolarization. In addition, during nine acute right ventricular outflow tract occlusions in a subset of six patients, monophasic action potential duration shortened (206.6 +/- 17.6 vs 221.7 +/- 20.9 msec, p less than .01) and early afterdepolarizations developed consistent with contraction-excitation feedback. These data suggest that, in humans, changes in mechanical load are associated with changes in ventricular repolarization consistent with contraction-excitation feedback.

Blue toe syndrome: treatment with anticoagulants and delayed percutaneous transluminal angioplasty

The spontaneous onset of a painful unilateral blue toe is usually caused by fibrinoplatelet microemboli arising from an upstream stenotic or occlusive lesion of the iliac or femoral artery. This constellation of findings is referred to as the blue toe syndrome (BTS). In 12 patients who experienced 14 spontaneous episodes of BTS, angiography demonstrated 15 proximal atherosclerotic arterial lesions, which were presumed to be the source of the microemboli. Fourteen of the 15 lesions were short-segment stenoses or occlusions distal to the aortic bifurcation. Six lesions were treated with antiplatelet or anticoagulant drugs followed by delayed percutaneous transluminal angioplasty (PTA) 6-12 weeks later. Three lesions were treated with surgical bypass, three with long-term anticoagulation, and one with transcatheter clot aspiration and immediate PTA. Two were treated with immediate thrombolytic therapy and had embolic complications. Antiplatelet and anticoagulant therapy followed by delayed PTA may be an effective alternative to surgery for treating BTS.

Thermodynamic correlates of hot tip laser angioplasty

Surface temperatures of normal human cadaver arteries and polytetrofluoroethylene grafts were measured in vitro using thermography to assess vascular wall heating from the metal-capped ("hot tip") laser probe. Laser pulse duration, vessel diameter, blood flow, and saline infusion were varied; power from an Argon laser was constant at 10 watts. The surface temperatures resulting in perforation were 76.2 +/- 2.2 degrees C for arteries and 90.4 +/- 2.1 degrees C for grafts. Blood flow provided an effective heat sink reducing artery and graft wall peak temperatures from 10 watt/5 sec pulses by 12.2 +/- 1.7 and 14.1 +/- 6.1 degrees C at 100 mL/min, and by 16.3 +/- 2.4 and 22.4 +/- 4.9 degrees C at 500 mL/min, respectively. In the occluded conduit, inflow of saline proximal to the probe tip reduced peak temperatures (degrees C) from 10 watt/5 sec pulses as follows: 14.0 +/- 3.2 (artery) and 23.2 +/- 8.5 (graft) at 50 mL/min, and 19.0 +/- 0.6 (artery) and 26.6 +/- 8.5 (graft) at 100 mL/min. Radial heating by the hot tip probe can cause thermal perforation. Blood flow or saline infusion modifies nontarget heating and may offer significant protection to the vasculature.

Evaluation of balloon angioplasty of coarctation restenosis by magnetic resonance imaging

Eight patients treated by balloon angioplasty for coarctation restenosis have been followed for 4 to 54 months (mean 40) by physical examination using Doppler pressures and by magnetic resonance imaging in a superconducting magnet operating at 0.6 tesla. Image analysis was performed by inspection and by measurement of the aorta, with particular attention to the angioplasty site and its relation to the ascending aorta at the same axial level. Similar measurements were made from immediate postangioplasty angiograms. Residual pressure gradients were 0 to 12 mm (mean 2), reflecting persistent absence of a gradient in 1 patient and further gradient reduction in 7. Images showed no aneurysm formation, mild residual or recurrent stenosis in 4 patients, minimal focal periaortic soft tissue thickening in 1 patient and an interval increase in the ratio of ballooned segment diameter to ascending aortic diameter in the 7 patients in whom it could be measured. Thus, intermediate-term results of balloon dilatation of coarctation restenosis are excellent and magnetic resonance imaging is well suited to the serial studies required in these patients.

Mesoatrial shunts for Budd-Chiari syndrome and inferior vena cava thrombosis: angiographic and hemodynamic evaluations

When inferior vena caval obstruction complicates the Budd-Chiari syndrome, conventional portosystemic shunts are not possible. The mesoatrial shunt has been devised to enable portal and sinusoidal decompression in these patients. Findings in 12 patients with Budd-Chiari syndrome and inferior vena caval obstruction in whom a mesoatrial shunt was performed are reported. Preoperative inferior vena cavography with pressure measurements is essential to determine the appropriate shunt procedure. Postoperatively, shunt patency is assessed with superior mesenteric arterial portography. Where possible, transvenous catheterization of the shunt is performed to confirm patency and assess hemodynamic function.

Interventional radiology: reflections and expectations. The 1985 Eugene P. Pendergrass new horizons lecture

The history and current practice of interventional radiology are reviewed. Interventional radiology is considered a subspecialty of diagnostic radiology that involves the use of a variety of percutaneous techniques to treat a spectrum of vascular and nonvascular diseases. It is physician intensive and requires a commitment to patient care analogous to that in surgery. Still considered in its infancy, interventional radiology should prosper and undergo continued growth over the next several decades.

The role of CT in the management of pelvic arteriovenous malformations

Four cases of pelvic arteriovenous malformations (AVM) were diagnosed and managed by CT, angiography, and embolotherapy. CT was used to determine the size, extent, and vascularity of each AVM and the involvement of adjacent organs. Thus CT was pivotal in the choice between surgical extirpation or embolotherapy. CT was also useful in monitoring patients following therapy.

Outpatient embolotherapy of varicocele

A detectable balloon technique for precise embolotherapy of varicocele has been developed. Results in 334 patients whose internal spermatic veins were occluded between 1979 and 1985 indicate satisfactory restoration of fertility with minimal morbidity and cost.

Long-segment femoropopliteal stenoses: is angioplasty a boon or a bust?

Analysis of 193 femoropopliteal angioplasties demonstrated patency rates in the stenotic group of 75.5% at 6 months and 54.4% at 54 months. The patency rates for the occlusive group were 93.7% at 6 months and 72.9% at 54 months; these rates were significantly better than those in patients with stenoses. A group of 14 patients with long-segment (greater than 7 cm) stenosis had the highest risk of early failure, with a 6-month patency of 23.1%. After removal of the long-segment stenosis group from the results, there were no significant differences between the long-term patencies for stenotic and occlusive lesions. If angioplasty of long stenoses is attempted, a high initial success rate but early failure should be anticipated.

Percutaneous spermatic vein occlusion: evaluation of sclerosing agents in experimental animals

The 5%-20% rate of recurrence of testicular varicoceles after embolotherapy has been a persistent clinical problem. Three sclerosing agents--sodium tetradecyl sulfate 3%, absolute ethanol, and 100 degrees C contrast material--were evaluated in canine spermatic veins for degree and durability of venous occlusion. Pathologic examination for perivenous, pulmonary, and neural changes was performed. Both sodium tetradecyl sulfate and absolute ethanol were effective sclerosants, but sodium tetradecyl sulfate was technically easier to use. The use of a sclerosant in conjunction with balloons or coils is the safest, most effective technique for occluding variococeles and minimizing postembolotherapy recurrences.

Vessel sizing wire: accurate vessel measurement using digital subtraction arteriography

A simple method of measuring vessel diameters using intraarterial digital subtraction angiography has been designed. With a catheter in place within the vessel of interest, a segmented guide wire with known dimensions is advanced into the catheter in the area to be measured. We have used the method successfully for balloon angioplasty as well as balloon embolization.

In situ saphenous vein bypass grafts: angiographic evaluation and interventional repair of complications

In situ saphenous vein grafts are being used with increasing frequency for bypass procedures involving the femoral and popliteal arteries. Complications of these procedures include anastomotic stenoses and persistent arteriovenous fistulae that may result in failure of the graft. Balloon angioplasty and embolotherapy with detachable balloons were employed successfully in three or four recent cases of patients with complications from in situ grafts. Tailored angiography is essential for evaluating in situ grafts, and interventional techniques are extremely useful for managing complications.

Interventional procedures in congenital heart disease

Balloon septostomy changed the natural history of transposition of the great arteries. Relatively little more occurred in catheter treatment of congenital heart disease until the development of the balloon catheter for transluminal angioplasty. Modification of these catheters led to successful treatment of valvular pulmonic stenosis, peripheral pulmonic stenosis, and coarctation restenosis. Possible future applications of balloon valvuloplasty include valvar aortic stenosis, stenotic shunts, and palliative operations. Pulmonary arteriovenous malformations are well managed by detachable balloon techniques, and balloons and coils are used for occluding large systemic collaterals. Interventional techniques have made a significant impact on the treatment of congenital heart disease, and it is anticipated that as technology improves further advances will occur.

Measurement of peripheral blood flow by thermodilution techniques

Recent advances in the diagnosis and treatment of cardiovascular pathology, including balloon angioplasty of atherosclerotic lesions in peripheral vascular disease, have led to an increased need for in vivo quantitation of blood flow. This study has three purposes: (1) to validate thermodilution techniques as a viable method for measuring low blood flow rates, (2) to calibrate accurately thermodilution catheters at these low flows, and (3) to develop an animal model that can be used to quantitate and compare many different flow measuring techniques. Modified commercially available 6F thermodilution catheters were used with a standard cardiac output computer to measure flows between 200 and 700 ml/minute. Eight anesthetized dogs were surgically interfaced with a variable flow, pressure, and compliance carotid-carotid/jugular bypass perfusion system. Three milliliters of normal saline at room temperature were injected through the catheters intra-arterially to measure different flows below, at, and above physiologic pressures and compliances. Results of this study indicate that with proper calibration, thermodilution techniques of measuring arterial and venous flows between 200 and 700 ml/minute are simple, accurate, and reliable. Using the designed system to generate known flows in vivo at various physiologic conditions allowed easy calibration of catheters and should facilitate calibration and comparison of other measurement techniques.

Liquid gold: low-osmolality contrast media

The use of low-osmolality versus high-osmolality contrast media is debated. The authors conclude that more studies need to be performed before the high cost of low-osmolality contrast media can justifiably be passed on to the patient population.

Long-term results of superficial femoral artery angioplasty

Short-term results of superficial femoral artery and popliteal percutaneous transluminal angioplasty have been good, but long-term results and factors influencing long-term patency are less commonly reported. One hundred thirty-seven superficial femoral artery angioplasties with follow-up for 54 months were reviewed. The 4-year patency for stenoses was 61% and for occlusions was 68%. If the initial result was clinically successful, the 4-year patency was not influenced by the quality or patency of runoff or by the length of the occlusion. Nineteen patients returned for redilatation, eight of whom had developed new lesions. Patency was adversely affected in patients with diabetes or with long-segment stenoses. Modifications of equipment and technique that may improve long-term patency rates are discussed.

Upper-extremity venography using digital subtraction angiography

Venography to evaluate the patency of upper-extremity veins was performed with digital subtraction angiography (DSA) and conventional angiography. Venous thrombosis was easily diagnosed, and the innominate veins and superior vena cava were more easily visualized using DSA. Iodine concentration for DSA was one-third that of conventional venography, and the examination time was reduced by 50% using DSA. Patient comfort and acceptance were greater with DSA. DSA is a superior technique for upper-extremity vein evaluation in cooperative patients.

Right-sided varicocele: technique and clinical results of balloon embolotherapy from the femoral approach

Among 227 patients undergoing outpatient balloon embolotherapy for varicocele, venography of the right internal spermatic vein (ISV) was attempted in 48. A percutaneous technique from the right femoral vein was used for all patients. The right ISV was successfully occluded with detachable balloons in 41 of 46 (89%), while in five (11%), the right ISV could not be embolized. A competent valve was found in two patients. The right ISV alone was embolized in ten patients: one had a solitary right varicocele, six had left varicoceles but competent valves in the left ISV, and three had recurrent left varicoceles after successful left ISV occlusion. Bilateral ISV embolization was achieved in 31 patients. Long-term follow-up study was available for 25 patients; 12 couples (48%) achieved a pregnancy. Percutaneous balloon occlusion of right varicoceles is a safe, effective outpatient technique.

Comparison of recurrent varicocele anatomy following surgery and percutaneous balloon occlusion

Venography of 44 recurrent varicoceles in 37 patients demonstrated different anatomical patterns of recurrence in surgical patients (26) compared to those treated by percutaneous balloon occlusion (18). The 3 types of patterns identified included parallel, renal vein and transcrotal collateral pathways. Virtually all surgical recurrences were owing to mid retroperitoneal (27 per cent) or low (inguinal) parallel collaterals (58 per cent). The majority of post-balloon occlusion recurrences were due to either high retroperitoneal parallel (44 per cent) or renal vein collaterals (28 per cent). Surgical recurrences were treated easily with percutaneous balloon occlusion. However, 39 per cent of the patients with recurrences following balloon embolization were not anatomical candidates for repeat percutaneous occlusion. We conclude that venous collaterals are identified easily by renal venography, and knowledge of these collaterals is helpful in planning further surgical or radiological treatment.

Biliary catheter drainage complicated by hemobilia: treatment by balloon embolotherapy

Seventeen patients experienced severe hemobilia following percutaneous (nine patients) or surgical (eight patients) placement of biliary drainage catheters. Fourteen patients bled early after catheter placement (0.5-32 weeks; mean, 5.4 weeks) and three bled late during long-term biliary drainage (1.1-3.6 years; mean, 2 years). Hepatic angiography demonstrated the source of bleeding in 15 (88%) patients (hepatic artery pseudoaneurysm in ten, hepatic artery-portal vein fistula in four, varix along the tube tract in one) but showed no source of bleeding in two. Thirteen patients with hemobilia were treated with embolotherapy, using detachable balloons in 12. The advantages of this technique included the ability to flow-direct the balloon without selective catheterization; the ability to test-inflate the balloon at the site of the aneurysm or fistula during angiographic study and adjust its position before detachment; and preservation of the hepatic artery proximal and distal to the inflated balloon, thus preserving hepatic function following embolization.

Cost incentives for peripheral angioplasty

Hospital costs and length of stay for 86 patients with peripheral vascular disease treated by bypass or percutaneous transluminal angioplasty (PTA) were assessed. The length of stay averaged 4-4.5 times longer, and the total hospital charge was 3-3.7 times greater, for bypass than for PTA. These charges are discussed in relation to current diagnosis-related groups (DRGs) and the allowed reimbursement from the Federal Prospective Payment System. In appropriately selected patients with peripheral vascular disease, PTA should be the treatment of choice from both medical and financial points of view.

Low-dose thrombolytic therapy for infrainguinal graft occlusions: an idea whose time has passed?

Despite the growing enthusiasm for low-dose intra-arterial thrombolytic therapy, the efficacy and risks in specific clinical situations have not been defined. During the past 13 months, 10 infrainguinal bypass graft occlusions occurred in nine patients 2 to 48 months postoperatively and were treated with local infusions of either streptokinase or urokinase. The grafts treated included two saphenous vein femoropopliteal grafts, two expanded polytetrafluoroethylene (PTFE) femoropopliteal grafts, four saphenous vein femoro-anterior tibial grafts, one saphenous vein-PTFE composite femoro-anterior tibial graft, and one saphenous vein-PTFE composite femoroperoneal graft. The graft occlusions occurred 2 to 14 days prior to initiation of treatment. The infusion failed to restore flow completely in seven grafts; and of the three successes, two patients required surgical treatment of complications. All successful recanalizations occurred within 48 hours of the initiation of thrombolytic therapy. Of the seven failures, two patients had viable limbs and were discharged, whereas two required amputation (one above and one below knee). Three patients underwent surgical thrombectomy and revisions that were successful in two and resulted in a below-knee amputation in the other. Despite all precautions, complications occurred in five patients. Low-dose intra-arterial thrombolytic therapy is a poorly efficacious, risky method of infrainguinal graft occlusion management.