Thallium-201 perfusion imaging with atrial pacing or dipyridamole stress testing for evaluation of cardiac risk prior to nonvascular surgery

Preoperative assessment of cardiac risk using thallium-201 scintigraphy and atrial pacing (n = 42) or dipyridamole stress testing (n = 35) was performed in 77 patients (mean age 65 +/- 7 years), who subsequently underwent elective nonvascular surgery. All patients were at low cardiac risk by clinical criteria; none could perform exercise stress testing due to physical limitations. ST depression consistent with ischemia occurred in 11 patients during atrial pacing and in 1 patient during dipyridamole stress testing (p less than 0.01). Nine patients had reversible perfusion defects with atrial pacing, and 10 patients with dipyridamole stress testing; fixed defects were present in 15 and 8 patients, respectively. Only one patient (fixed perfusion defect with atrial pacing, left main disease on coronary angiography) underwent preoperative coronary revascularization. Two patients subsequently had postoperative cardiac events. One patient (reversible perfusion defect with dipyridamole stress testing) experienced sudden death after a nonvascular procedure, while a second patient (normal thallium images with dipyridamole testing) had a nonfatal myocardial infarction. In patients having atrial pacing or dipyridamole stress testing, thallium-201 scans that are normal or show only a fixed perfusion defect confirm a low risk of cardiac complications following nonvascular surgery. The presence of a reversible perfusion defect does not preclude a postoperative course free of cardiac complications in patients at low cardiac risk by clinical criteria.

Tissue plasminogen activator and penetrating keratoplasty

We report a patient who developed severe intraocular fibrin formation following penetrating keratoplasty and vitrectomy surgery. The fibrin response worsened despite aggressive treatment with topical steroids. On the second postoperative day, 25 micrograms of intracameral tissue plasminogen activator was administered, resulting in rapid resolution of the fibrin response. The graft remained clear. We believe tissue plasminogen activator may be useful in selected cases of severe, recalcitrant postkeratoplasy fibrin formation.

Relaxing retinotomies and retinectomies. Surgical results and predictors of visual outcome

Functional and anatomic success after relaxing retinotomy may be limited by recurrent retinal detachment or severe hypotony. Fifty-four consecutive eyes undergoing relaxing retinotomy for proliferative vitreoretinopathy (42 eyes) and trauma (12 eyes) were analyzed to determine whether perioperative factors, including size and location of the retinotomy, influenced visual or anatomic outcome. After 6 months' minimum follow-up, anatomic success (retina attached posterior to buckle and an intraocular pressure of 3 mm Hg or more) was achieved in 35 eyes (64%). Functional success (visual acuity of 5/200 or better) was achieved in 14 eyes (26%). Factors predicting functional success by stepwise logistic regression analysis included a preoperative visual acuity of hand motions or better and location of the retinotomy in the superior four clock hours of the fundus. Causes of anatomic failure included proliferative vitreoretinopathy (11 eyes) and severe hypotony or phthisis (8 eyes). Superior location of the retinotomy and visual acuity of hand motions or better favorably influenced visual outcome after relaxing retinotomy.

Clearance of experimental vitreous hemorrhage after panretinal cryotherapy is related to macrophage influx

We investigated the effect of panretinal cryotherapy on blood clearance and on the inflammatory cellular response in rabbit eyes with experimental vitreous hemorrhage. Eyes treated with cryotherapy demonstrated less extensive vitreous opacity and more rapid clearance of blood than untreated eyes. The peak inflammatory cellular response measured by counts or radiolabeled cells in the optic nerve was 2.5 times greater in the cryotherapy-treated eyes. Panretinal cryotherapy may promote the clearance of vitreous hemorrhage by stimulating the influx of increased numbers of phagocytic inflammatory cells.

Tissue plasminogen activator for postvitrectomy fibrin formation

The authors injected 25 micrograms of recombinant tissue plasminogen activator (tPA) into the anterior chamber or vitreous cavity of 23 eyes of 22 patients with severe intraocular fibrin formation that developed after vitrectomy surgery for complicated cases of proliferative vitreoretinopathy (PVR) (13 eyes), diabetic traction retinal detachment (TRD) (7 eyes), or endophthalmitis (3 eyes). Tissue plasminogen activator injected an average (+/- standard deviation) of 73 +/- 63 hours after vitrectomy surgery resulted in complete fibrinolysis in 21 of 23 eyes and partial fibrinolysis in one eye. The mean time to fibrin resolution was 3.0 +/- 1.0 hours. Four eyes required repeat tPA injection for recurrent fibrin formation; repeat injection resulted in complete fibrinolysis in each case. The mean follow-up duration after tPA administration was 6 months. At the final follow-up examination, the retina was totally attached in 18 of 23 eyes and was partially attached in 2. Visual acuity improved in 12 eyes (52%); it was at least 20/400 in 8. Complications of tPA injection included hyphema (2 patients) and corneal stromal thickening (2 patients). Mild, transient, periocular pain that was easily managed with non-narcotic analgesia developed in three patients.

Myocarditis: a clinical perspective

Myocarditis can have many diverse presentations ranging from ventricular arrhythmias to congestive heart failure, secondary to dilated cardiomyopathy. The recent resurgence of endomyocardial biopsy has greatly enhanced our ability to diagnose this intriguing entity. The biopsy has shown that unexplained arrhythmias have a 15% to 29% incidence of myocarditis, while those with an idiopathic congestive cardiomyopathy have a biopsy-proved range of 9% to 63%. The cause of this process has, at times, been blamed on viruses, but definite cause-and-effect relationships are mostly conjecture and anecdotal. The current role of immunosuppressive therapy in myocarditis is potentially promising, and may alter the subsequent course of the illness.

Posterior segment manifestations of ocular trauma

Nonpenetrating or blunt ocular trauma, orbital trauma and systemic trauma may cause a variety of posterior segment abnormalities. Blunt ocular trauma may cause damage to the retina (commotio retinae), retinal pigment epithelium (retinal pigment epithelial edema), choroid (choroidal rupture) and optic nerve (optic nerve evulsion) alone or in combination. Traumatic macular holes and retinal detachment or dialysis may also occur after blunt ocular trauma. Trauma to the orbital tissues adjacent to the globe can cause concussive forces with damage to multiple structures within the eye (chorioretinitis sclopetaria). Systemic trauma may result in diffuse retinopathy (Purtscher's retinopathy, shaken baby syndrome) or localized retinal abnormalities (whiplash retinopathy, fat embolism syndrome). Alterations in intravascular (Valsalva retinopathy) or intracranial pressure (Terson's syndrome) due to a variety of causes may result in preretinal or vitreous hemorrhage and associated visual loss. The purpose of this report is to review each of these entities of traumatic posterior segment abnormalities.

Prognostic value of atrial pacing and thallium-201 scintigraphy in patients with stable chest pain

The value of atrial pacing and thallium-201 scintigraphy for assessing risk of subsequent cardiac events was examined in 210 patients with stable chest pain. Follow-up information was complete in 195 patients (mean age 61 years). Over an average follow-up of 19 months, cardiac events occurred in 38 patients--unstable angina in 20, nonfatal acute myocardial infarction in 6 and death from cardiac causes in 12. A history of previous myocardial infarction, diabetes mellitus, systemic hypertension or peripheral vascular disease at the time of pacing was not associated with an increased frequency of subsequent cardiac events. Six of 38 patients with later cardiac events had a history of congestive heart failure, compared with 8 of 157 without cardiac events (p less than 0.05). Neither pacing-induced angina, ST depression, nor the presence of a fixed perfusion defect was significantly more frequent in patients with cardiac events as a whole compared with patients without such events. Reversible defects and abnormal scans (reversible or fixed defects) were present, respectively, in 19 and 31 of 38 patients with cardiac events, compared with 42 and 79 patients, respectively, of the 157 patients without cardiac events (both p less than 0.01). In patients who developed unstable angina, a reversible defect was seen in 13 and an abnormal scan in 16 (both p less than 0.01 compared with patients without cardiac events). In 12 patients who died from a primary cardiac event, fixed defects were present in 8 and an abnormal scan in 11 (p less than 0.05 and p less than 0.01, respectively, compared with patients without cardiac events).(ABSTRACT TRUNCATED AT 250 WORDS)

Preoperative evaluation of cardiac risk by means of atrial pacing and thallium 201 scintigraphy

Atrial pacing and thallium 201 scintigraphy were done in 61 patients with known or suspected coronary artery disease referred for evaluation of cardiac risk before elective vascular surgery. All patients had noncardiac limitations precluding performance of an adequate exercise stress test. Before atrial pacing all were considered to be at low risk of a postoperative cardiac event based on assessment of clinical parameters. Vascular surgery was subsequently performed in 47 patients. In these patients, pacing-induced ST segment depression greater than or equal to 1 mm occurred in 18, a fixed perfusion defect occurred in 11, and a reversible defect occurred in six. Two of the six patients with reversible perfusion defects had preoperative coronary angiography; both had significant coronary artery disease (one or more lesions greater than or equal to 50%). Two patients (one of whom had a reversible perfusion defect) underwent preoperative coronary revascularization and tolerated subsequent vascular surgery well. All other patients received only medical therapy. None of the 47 patients undergoing vascular surgery had a postoperative cardiac event (unstable angina, congestive heart failure, myocardial infarction, or cardiac death). Of the 14 patients in whom vascular surgery was deferred or canceled, surgery was canceled for noncardiac reasons in seven. Six of these seven patients had a normal perfusion scan; none had a reversible perfusion defect or marked (greater than or equal to 2 mm) ST segment depression. No cardiac event occurred during a 3-month period after atrial pacing in any of these patients. Six of the remaining seven patients had reversible perfusion defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Subretinal membranes in proliferative vitreoretinopathy

Subretinal membranes (SRMs) are an important but rarely identified component of proliferative vitreoretinopathy (PRV). In 153 consecutive cases that had vitreoretinal surgery for this condition and were followed for at least 6 months, SRMs were encountered in 72 eyes (47%). In 20 (28%) of the 72 eyes, the SRMs prevented complete retinal reattachment and needed to be removed or excised through one or multiple retinotomies. Intraoperative complications related to the SRMs or their removal included choroidal or retinal hemorrhage in three eyes (15%), subretinal air in three eyes (15%), and unplanned extension of the retinotomies in two eyes (10%). The 20 eyes requiring SRMs removal were followed for a median of 11 months. Retinas were reattached in 13 eyes (65%), although only 4 eyes (20%) had a visual acuity of 5/200 or better. Recognizing SRMs as a component of PVR is important in helping to maximize the anatomic success rate although the effects on visual function are not fully known.

Treatment of postvitrectomy fibrin pupillary block with tissue plasminogen activator

We injected 25 micrograms of recombinant tissue plasminogen activator into the anterior chamber or the vitreous cavity in seven aphakic patients for pupillary block caused by a complete fibrin pupillary membrane that formed after vitrectomy with fluid-gas exchange. Progressive fibrin deposition resulted in pupillary block by three days after vitrectomy surgery in six patients, and seven days after vitrectomy in one patient. The pupillary block was associated with increased intraocular pressure in six patients. Tissue plasminogen activator was injected via the corneoscleral limbus in five patients and via the pars plana in two patients. In all patients, injection of tissue plasminogen activator resulted in complete fibrinolysis of the fibrin pupillary membrane within four hours, associated with a deepening of the anterior chamber. In the six patients with increased intraocular pressure at the time of tissue plasminogen activator injection, dissolution of the fibrin membrane was associated with a decrease in pressure. In all patients, intraocular pressure had returned to normal by three days after the injection. No complications were associated with the injection.

Illuminated retinal picks for vitreous surgery

We developed a new illuminated disposable retinal pick system for use in vitreoretinal surgery. These instruments facilitate bimanual dissection of proliferative tissue while allowing ocular endoillumination. We have found these instruments to be helpful in the management of complicated retinal detachment due to proliferative diabetic retinopathy or proliferative vitreoretinopathy.

Results of vitrectomy for diabetic traction retinal detachments using the en bloc excision technique

En bloc excision is a technique in which fibrovascular diabetic membranes and the posterior hyaloid are separated from the retina as a single unit. In a consecutive series of 69 eyes with diabetic traction retinal detachment treated with this technique, initial retinal reattachment was accomplished in 100% (69/69) of the eyes. With a minimum of 6 months' follow-up, the retina remained completely attached in 83% (57/69) of eyes, while the macula was attached in 88% (61/69) of eyes. Final visual acuity was 5/200 or better in 71% (49/69) of eyes. While current surgical techniques allow a high rate of anatomic success in the repair of diabetic traction retinal detachment, visual results remain limited by irreversible alterations in retinal function.

Diagnostic value of atrial pacing and thallium-201 scintigraphy for the assessment of patients with chest pain

Atrial pacing was performed either alone (n = 23) or in combination with thallium-201 scintigraphy (n = 113) in 136 patients referred for evaluation of chest pain. The presence of coronary artery disease (CAD) was excluded by cardiac catheterization in 12 patients and confirmed in 124. Both pacing-induced ST depression and angina had sensitivities of 48% for CAD; specificities were 75% and 83%, respectively. An abnormal thallium-201 scan (one or more reversible and/or fixed perfusion defects) was seen in 72% of patients with CAD (specificity 83%). Reversible perfusion defects were present in 47% of patients with CAD (specificity 83%), and fixed defects in 36% (specificity 100%). Pacing was associated with either ST depression or an abnormal perfusion scan in 81% of patients (specificity 67%). There were no significant differences in the results of atria pacing or thallium-201 scintigraphy in patients with or without a history of myocardial infarction, or in those with or without previous coronary artery bypass surgery. Pacing-induced ST depression, or both ST depression and a reversible perfusion defect occurred significantly less frequently in patients with peripheral vascular disease than in those without this diagnosis (p less than .05). With only one exception, there were no significant differences in the sensitivities of any indicators of ischemia (ST depression, angina, or perfusion scans), either individually or in combination, as the peak pacing rate or double product achieved increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial pacing and thallium-201 scintigraphy in patients with chest pain: correlation with coronary anatomy

Atrial pacing and thallium-201 scintigraphy were performed in 72 patients referred for evaluation of chest pain. Coronary artery disease (CAD) was present in 63 patients, as documented by cardiac catheterization performed at the same time or within 2 months of atrial pacing. Nine patients had no or insignificant (less than 50% stenosis) CAD. The sensitivity of pacing-induced angina for CAD was 51%, and was 49% for ST depression. Specificities were 89% and 78%, respectively. A reversible perfusion defect was seen in 54% of patients with CAD (specificity 89%), and a fixed defect in 29% (specificity 100%). The sensitivity of an abnormal thallium-201 scan (one or more reversible or fixed defects) was 79% (p less than 0.05 compared to angina or ST depression). Combined sensitivity of ST depression and/or an abnormal thallium-201 scan was 87%. There were no significant changes in any of these sensitivities as the number of vessels with CAD increased. Thallium-201 scintigraphy correctly identified 11 of 19 (58%) patients with single-vessel disease as having CAD in only one vessel, but underestimated the extent of disease in all but a few patients with multivessel disease. The sensitivity of perfusion imaging to identify lesions in specific vessels ranged from 27% (circumflex) to 57% (right coronary artery). Specificities were 100% for circumflex, 78% for anterior descending, and 83% for right coronary artery lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of right ventricular ejection fraction by two-dimensional echocardiographic single plane subtraction method

Right ventricular ejection fraction is a useful measurement for evaluating right ventricular function in various states, including coronary artery disease, chronic obstructive pulmonary disease, and both congenital and valvular heart diseases. The right ventricular geometry has made it difficult to evaluate right ventricular ejection fraction by simple echocardiographic methods. In this study 36 consecutive patients were examined by two-dimensional echocardiography within 4 hours of radionuclide-determined right ventricular ejection fraction to test a simplified method for calculating right ventricular ejection fraction by two-dimensional echocardiography. Echocardiographic measurements were independently determined in the subcostal and apical four-chamber views. Correlation with first pass radionuclide right ventricular ejection fraction was r = 0.89 and 0.84. Right ventricular ejection fraction could be calculated from one of two views in 92% of patients studied. This technique for determination of right ventricular ejection fraction offers a simple noninvasive method of evaluating right ventricular function.

Photoablation of ocular melanoma with a high-powered argon endolaser

We studied the use of a 15-W argon blue-green laser in the treatment of choroidal melanoma in a rabbit model. Greene melanoma cells were used to produce 2- to 4-mm thick tumors posteriorly in the suprachoroidal space in pigmented rabbits. Endophotocoagulation delivered through a 600-micron fiberoptic probe was performed to ablate the tumor tissue and a surrounding margin of normal tissue. A vitreous cutter was used simultaneously to remove liberated necrotic debris. The effect of the laser on tumor and normal ocular tissue was evaluated by light microscopy and the extent of the proliferative response by tritiated thymidine radioautography. Application of 100 to 400 pulses of laser energy using treatment parameters of 12 to 14 W of power and 0.1-s pulses resulted in complete ablation of melanoma tissue, overlying retina, and choroid. There was no substantial intraoperative or postoperative hemorrhage. Material liberated during the laser treatment was found to be nonviable. The effect of the laser on tissue appeared localized to within approximately 1.25 mm of the margin of the central lesion. The high-energy argon laser seems to offer a means of effectively ablating melanoma tissue via an internal resection approach.

Structural Studies of Technetium Complexes. XI. The Crystal Structure of Bis(tetraphenylarsonium) Bis(1,2-dicyanoethenedithiolato)nitridotechnetate(V)

The crystal structure of [AsPh4]2 [ TcN(mnt)2] ( mnt = 1,2-dicyanoethenedithiolate) has been determined by single-crystal X-ray diffraction methods at 21 � 1 C. Crystals are monoclinic, space group Pn , with a 11 369(2), b 15.530(2), c 14.421(3) � , P 97.58(2)�, and Z 2. Full-matrix least-squares refinement gave a final R value of 0.057 for 4232 independent reflections. The technetium atom in the [TcN( mnt )2]2- anion has square-pyramidal coordination geometry with the nitrido ligand in the apical position, Tc =N 1.59(1) � , and four Tc -S bonds with distances varying between 2.367(4) and 2.419(4) �. The Tc =N core is disordered about a pseudo-inversion centre, but unequal occupancies of the disordered sites preclude a centrosymmetric structure.