Jonathan P. Gertler

Vascular complications associated with spontaneous aortic dissection

Three hundred twenty-five cases of spontaneous aortic dissection seen at two institutions between 1965 and 1986 were reviewed to assess the incidence, morbid sequelae, and specific management of aortic branch compromise. Noncardiac vascular complications occurred in 33% of the study group, and in these patients the overall mortality rate (51%) was significantly (p less than 0.001) higher than in patients without (29%) such complications. Although aortic rupture was the strongest correlate of mortality (90%), death specifically related to vascular occlusion was common when such occlusion occurred in the carotid, mesenteric, and renal circulation. There was a strong correlation between stroke and carotid occlusion (22/26 cases), yet specific carotid revascularization was only used during the chronic phase of the disease. Similarly, peripheral operation was ineffective in reducing the mortality rate in the setting of mesenteric (87%) and renal (50%) ischemia. Fifteen patients required either fenestration or graft replacement of the abdominal aorta for acute obstruction, rupture, or chronic aneurysm development. Thirty-eight patients (12%) demonstrated some degree of lower extremity ischemia, and one third of these required a direct approach on the abdominal aorta or iliofemoral segments to restore circulation. Selected patients with acute aortic dissection may require peripheral vascular operation in accordance with a treatment strategy that directs initial attention to the immediate life-threatening complications.

Initial experience with endovascular aneurysm repair: Comparison of early results with outcome of conventional open repair

PURPOSE To determine the safety, effectiveness, and problems encountered with endovascular repair of abdominal aortic aneurysm (AAA). Initial experience with endoluminal stent grafts was examined and compared with outcome for a matched concurrent control group undergoing conventional operative repair of AAA. METHODS Over a 3-year period, 30 patients underwent attempts at endovascular repair of infrarenal AAA. Of the 28 (93%) successfully implanted endografts, 8 were tube endografts, 8 bifurcated grafts, and 12 aortouniiliac grafts combined with femorofemoral bypass. Most of the procedures were performed in the past year because the availability of bifurcated and aortoiliac endografts markedly expanded the percentage of patients with AAA who might be treated with endoluminal methods. The follow-up period ranged from 1 to 44 months, with a mean value of 11 months. RESULTS Endovascular procedures demonstrated significant advantages with respect to reduced blood loss (408 versus 1287 ml), use of an intensive care unit (0.1 versus 1.75 days), length of hospitalization (3.9 versus 10.3 days), and quicker recovery (11 versus 47 days). Although the total number of postoperative complications was identical for the two groups, the nature of the complications differed considerably. Local and vascular complications characteristic of endovascular repair could frequently be corrected at the time of the procedure and tended to be less severe than systemic or remote complications, which predominated among the open surgical repair group. On an intent-to-treat basis, 23 (77%) of the 30 AAAs were successfully managed with endoluminal repair. The seven (23%) failures were attributable to two immediate conversions caused by access problems, three persistent endoleaks, one late conversion caused by AAA expansion, and one late rupture. CONCLUSIONS Although less definitive than those for conventional operations, these early results suggest that endovascular AAA repair offers considerable benefits for appropriate patients. The results justify continued application of this method of AAA repair, particularly in the treatment of older persons at high risk.

Clinical experience with epidural cooling for spinal cord protection during thoracic and thoracoabdominal aneurysm repair

PURPOSE This report summarizes our experience with epidural cooling (EC) to achieve regional spinal cord hypothermia and thereby decrease the risk of spinal cord ischemic injury during the course of descending thoracic aneurysm (TA) and thoracoabdominal aneurysm (TAA) repair. METHODS During the interval July 1993 to Dec. 1995, 70 patients underwent TA (n = 9, 13%) or TAA (n = 61) (type I, 24 [34%], type II, 11 [15%], type III, 26 [37%]) repair using the EC technique. The latter was accomplished by continuous infusion of normal saline (4 degrees C) into a T11-12 epidural catheter; an intrathecal catheter was placed at the L3-4 level for monitoring of cerebrospinal fluid temperature (CSFT) and pressure (CSFP). All operations (one exception, atriofemoral bypass) were performed with the clamp-and-sew technique, and 50% of patients had preservation of intercostal vessels at proximal or distal anastomoses (30%) or by separate inclusion button (20%). Neurologic outcome was compared with a published predictive model for the incidence of neurologic deficits after TAA repair and with a matched (Type IV excluded) consecutive, control group (n = 55) who underwent TAA repair in the period 1990 to 1993 before use of EC. RESULTS EC was successful in all patients, with a 1442 +/- 718 ml mean (range, 200 to 3500 ml) volume of infusate; CSFT was reduced to a mean of 24 degrees +/- 3 degrees C during aortic cross-clamping with maintenance of core temperature of 34 degrees +/- 0.8 +/- C. Mean CSFP increased from baseline values of 13 +/- 8 mm Hg to 31 +/- 6 mm Hg during cross-clamp. Seven patients (10%) died within 60 days of surgery, but all survived long enough for evaluation of neurologic deficits. The EC group and control group were well-matched with respect to mean age, incidence of acute presentations/aortic dissection/aneurysm rupture, TAA type distribution, and aortic cross-clamp times. Two lower extremity neurologic deficits (2.9%) were observed in the EC patients and 13 (23%) in the control group (p < 0.0001). Observed and predicted deficits in the EC patients were 2.9% and 20.0% (p = 0.001), and for the control group 23% and 17.8% (p = 0.48). In considering EC and control patients (n = 115), variables associated with postoperative neurologic deficit were prolonged (> 60 min) visceral aortic cross-clamp time (relative risk, 4.4; 95% CI, 1.2 to 16.5; p = 0.02) and lack of epidural cooling (relative risk, 9.8; 95% CI, 2 to 48; p = 0.005). CONCLUSION EC is a safe and effective technique to increase the ischemic tolerance of the spinal cord during TA or TAA repair. When used in conjunction with a clamp-and-sew technique and a strategy of selective intercostal reanastomosis, EC has significantly reduced the incidence of neurologic deficits after TAA repair.

Clinical outcome of internal iliac artery occlusions during endovascular treatment of aortoiliac aneurysmal diseases.

PURPOSE To determine the clinical outcome of hypogastric artery occlusion in patients who underwent endovascular treatment of aortoiliac aneurysmal disease. MATERIAL AND METHODS From January 1994 to March 1998, 94 patients underwent endovascular treatment of aneurysmal diseases involving the infra-abdominal aorta or iliac arteries. Preoperative and intraoperative radiologic data were reviewed. Discharge summaries, clinic visits, and phone calls formed the basis for clinical follow-up, with a mean follow-up period of 7.3 months (range, 1-24 months). RESULTS Because of the anatomy of the aneurysms, 28 patients required occlusion of one or more hypogastric arteries. One of the 28 patients died of unrelated causes before follow-up. Seven (26%) of the remaining 27 patients developed symptoms attributable to the hypogastric artery occlusions. Five patients developed new buttock or thigh claudication; of these five patients, three with initially mild symptoms noted complete or near complete resolution of symptoms upon follow-up. One patient with originally significant claudication at 2-year follow-up noted near resolution of symptoms. The other patient with severe pain did not improve significantly on final 1-year follow-up before his death (of unrelated causes). Other clinical complications were worsening sexual function in one patient and a nonhealing sacral decubitus ulcer that developed in a debilitated patient in the postoperative setting, which required surgery. No bowel ischemia was observed. CONCLUSION When treating aortoiliac aneurysmal disease through an endovascular approach, the occlusion of internal iliac artery is often necessary but carries with it a small but finite chance of morbidity.

Magnetic resonance angiography in the management of lower extremity arterial occlusive disease: a prospective study.

PURPOSE We conducted a prospective study to clarify the clinical utility of magnetic resonance angiography (MRA) in the treatment of patients with lower extremity arterial occlusive disease. METHODS During the interval of September 1993 through March 1995, 79 patients (43% claudicants, 57% limb-threatening ischemia) were studied with both MRA and contrast arteriography (ANGIO) and underwent intervention with either balloon angioplasty (9%), surgical inflow (28%), or outflow (63%) procedures. MRA and ANGIO were interpreted by separate blinded vascular radiologists, and arterial segments from the pelvis to the foot were graded as normal or with increasing degrees of mild (25% to 50%), moderate (51% to 75%), or severe (75% to 99%) stenosis or occlusion. Treatment plans were formulated by the attending surgeon and were based initially on hemodynamic, clinical, and MRA data and thereafter with ANGIO. Additional study surgeons formulated independent and specific treatment plans based on MRA or ANGIO alone. Indexes of agreement (beyond chance) for arterial segments depicted by MRA and ANGIO were assessed (kappa value), and treatment plans formulated were compared (chi-square). RESULTS Precise agreement (%) and the percent of major discrepancies (segment classified as normal/mild stenosis on one study and severe stenosis/occlusion on the other) between MRA and ANGIO for respective arterial segments was as follows: common and external iliacs (n = 256) 77/3.5; superficial femoral and above-knee popliteal (n = 255) 73/6.7; below-knee popliteal (n = 131) 84/3.8; infrapopliteal runoff vessels (n = 864) 74/12.4; pedal vessels (n = 111) 69/19.8 Kappa values indicated moderate agreement (between MRA and ANGIO) beyond chance for all arterial segments. Treatment plans formulated by the attending surgeon, the MRA surgeon, and the ANGIO surgeon agreed in more than 85% of cases. Inability of MRA to assess the significance of inflow disease and inadequate detail of tibial/pedal vessels were the principal deficiencies of MRA in those cases where it was considered an inadequate examination. CONCLUSION These findings suggest MRA and ANGIO are nearly equivalent examinations in the demonstration of infrainguinal vascular anatomy. MRA is an adequate preoperative imaging study (and may replace ANGIO), particularly in those circumstances when the risk of ANGIO is increased or when clinical and hemodynamic evaluation predict the likelihood of straightforward aortofemoral or femoral-popliteal reconstruction.

Renal artery reconstruction for the preservation of renal function

PURPOSE We reviewed a 13-year experience with an emphasis on long-term survival and renal function response when renal artery reconstruction (RAR) was performed primarily for the preservation or restoration of renal function in patients who had atherosclerotic renovascular disease. METHODS From January 1, 1980, to June 30, 1993, 139 patients underwent RAR for renal function salvage and were retrospectively reviewed. Inclusion criteria were either preoperative serum creatinine level > 2.0 mg/dl (67% of patients) or RAR to the entire functioning renal mass irrespective of baseline renal function. Patient survival was calculated by life-table methods. Cox regression analysis was used to determine relative risk (RR) estimates for the late outcomes of continued deterioration of renal function and late survival after RAR. A logistic regression model was used to evaluate variables associated with perioperative complications. RESULTS Clinical characteristics of the cohort were notable for advanced cardiac (history of congestive heart failure, 27%; angina, 22%; previous myocardial infarction, 19%) and renal disease (serum creatinine level < 2.0 mg/dl, 33%; 2.0 mg/dl to 3.0 mg/dl, 40%, > 3.0 mg/dl, 27%). Cardiac disease was the principle cause of early (6 of 11 operative deaths) and late death. Operative management consisted of aortorenal bypass in 47%, extraanatomic bypass in 45%, and endarterectomy in 8%; 45% of patients required combined aortic and RAR. The operative mortality rate was 8%; significant perioperative renal dysfunction occurred in 10%. Major operative morbidity was associated with increasing azotemia (RR = 2.1; p = 0.001; 95% confidence interval [CI], 1.3 to 4.7 for each 1.0 mg/dl increase in baseline creatinine level). Of those patients who had a baseline creatinine level > or = 2.0 mg/dl, 54% had > or = 20% reduction in creatinine level after RAR. Late follow-up data were available for 87% of operative survivors at a mean duration of 4 years (range, 6 weeks to 12.6 years). Actuarial survival at 5 years was 52% +/- 5%. Continued deterioration in renal function occurred in 24% of patients who survived operation, and eventual dialysis was required in 15%. Deterioration of renal function after RAR was associated with increasing levels of preoperative creatinine (RR = 1.6; 95% CI, 1.2 to 1.8; p = 0.001 for each 1.0 mg/dl increment in baseline creatinine level), and inversely related to early postoperative improvement in creatinine level (RR = 0.41; 95% CI, 0.2 to 0.9; p = 0.04). CONCLUSIONS Intervention before major deterioration in renal function and an aggressive posture toward the frequently associated coronary artery disease are necessary to improve long-term results when RAR is performed for renal function salvage.

Ambient oxygen tension modulates endothelial fibrinolysis

PURPOSE Vascular procedures reoxygenate ischemic endothelial cells (EC) and arterialize saphenous vein (HSV) EC. The balance between the EC-derived fibrinolytic components, plasminogen activator (tPA), and plasminogen inhibitor (PAI-1) contributes to maintaining thromboresistance. This balance also affects proteolysis through plasmin generation, mediating matrix metabolism endothelial migration, angiogenesis, and theoretically affecting the development of intimal hyperplasia. METHODS To explore the impact of varying oxygen tensions on EC fibrinolysis, HSV and human umbilical vein (HUV) were subjected to Po2 of 40 mm Hg for 24 hours with restoration of Po2 to 150 mm Hg for 24 hours. The tPA and PAI-1 antigen and tPA/PAI-1 antigen ratio in conditioned media (CM), expressed as increases or decreases % change, normalized for cell count, versus controls, were analyzed by enzyme-linked immunosorbent assay. Cellular tPA and PAI-1 mRNAs were assessed by Northern analysis. RESULTS The tPA but not PAI-1 was significantly decreased after the first 24 hours in HSVEC and significantly decreased after 48 hours in both HUVEC and HSVEC when compared with controls. Messenger RNA for tPA was unchanged but PAI-1 mRNA increased significantly for HSVEC and HUVEC after 24 hours of Po2 of 40 mm Hg, returning to baseline within 24 hours of Po2 to 150 mm Hg restoration. CONCLUSIONS These data support the hypothesis of a fibrinolytic shift after altered ambient O2 tensions exposure in endothelium and demonstrate that HSVEC are more sensitive to altered O2 tension than HUVEC. Altered O2 tensions depress EC fibrinolysis in this model.

Carotid endarterectomy for unstable and compelling neurologic conditions: Do results justify an aggressive approach?

PURPOSE In a retrospective study the outcome of 70 carotid endarterectomies (CEA) in 68 patients with neurologically unstable conditions or anatomically compelling findings on carotid angiography was examined to more accurately identify patients who might benefit from CEA in this setting. METHODS Out of a total of 1734 CEAs performed from 1978 to 1992, five groups of patients were selected: group A, stroke in evolution with tight stenosis (n = 5); group C, crescendo transient ischemic attacks (CTIA) continuing despite heparin (n = 14); group D, CTIA (above criteria) ceasing with heparin (n = 21); and group E, anatomically compelling situation on carotid angiography (n = 13). Data collected included preoperative and postoperative Neurologic Event Severity Score (NESS), CHAT classification, arteriosclerosis risk factors, demographics, and long-term overall and transient ischemic attack/stroke-free survival rates. RESULTS Risk factors and demographics were similar in all groups. By NESS criteria the conditions of 97.3% of patients in the neurologically unstable groups A to C were improved or stabilized after operation, with one deterioration (2.7%). All patients in group B either stabilized or improved. In group D, one patients NESS deteriorated, resulting in 3.5% overall morbidity rate and no deaths for groups A to D. Follow-up showed an overall survival rate by Kaplan-Meier analysis equivalent to a matched control population, with 85% alive at 5 years. The cumulative TIA/stroke-free survival rate at 5 years was 75%. CONCLUSIONS In this retrospective series, CEA performed for compelling or unstable neurologic findings carried low morbidity and mortality rates. Early aggressive surgical therapy of neurologically unstable patients may be warranted because our results improved on the anticipated natural history of the conditions studied. Further clarification of proper patient selection is necessary before this principle can be applied broadly.

The effects of external compression on venous blood flow and tissue deformation in the lower leg.

External pneumatic compression of the lower legs is effective as prophylaxis against deep vein thrombosis. In a typical application, inflatable cuffs are wrapped around the patients legs and periodically inflated to prevent stasis, accelerate venous blood flow, and enhance fibrinolysis. The purpose of this study was to examine the stress distribution within the tissues, and the corresponding venous blood flow and intravascular shear stress with different external compression modalities. A two-dimensional finite element analysis (FEA) was used to determine venous collapse as a function of internal (venous) pressure and the magnitude and spatial distribution of external (surface) pressure. Using the one-dimensional equations governing flow in a collapsible tube and the relations for venous collapse from the FEA, blood flow resulting from external compression was simulated. Tests were conducted to compare circumferentially symmetric (C) and asymmetric (A) compression and to examine distributions of pressure along the limb. Results show that A compression produces greater vessel collapse and generates larger blood flow velocities and shear stresses than C compression. The differences between axially uniform and graded-sequential compression are less marked than previously found, with uniform compression providing slightly greater peak flow velocities and shear stresses. The major advantage of graded-sequential compression is found at midcalf. Strains at the lumenal border are approximately 20 percent at an external pressure of 50 mmHg (6650 Pa) with all compression modalities.

Diagnosis and treatment of thoracic aortic intramural hematoma

PURPOSE This report reviews our recent experience with nine patients who had intramural hematoma of the thoracic aorta. METHODS This was a retrospective study of all patients who had intramural hematoma at our institution from 1989 to 1994. Patients who had identifiable intimal flap, tear, or penetrating aortic ulcer were excluded from the study. RESULTS Among these nine elderly patients (mean age, 76 years), the most common presentation was chest or back pain. Intramural hematoma was diagnosed by a variety of high-resolution imaging techniques. The descending thoracic aorta alone was involved in seven patients, whereas the ascending aorta was affected in the other two patients. One patient had evidence of an aneurysm (5.0 cm diameter) in the region of the hematoma. All patients were initially managed nonsurgically with blood pressure control. Both patients who had ascending aortic involvement had progression of aortic hematoma, which resulted in death in one case and in successful surgery in the other. Six of the seven patients who had descending aortic involvement alone were successfully managed without aortic surgery. The patient who had intramural hematoma and associated aortic aneurysm, however, had severe, recurrent pain and underwent successful aortic replacement. Another patient had recurrent pain associated with hypertension, but was successfully managed nonsurgically with antihypertensive therapy. All eight survivors are doing well at a median follow-up of 19 months. CONCLUSIONS Intramural hematoma appears to be a distinct entity, although overlap with aortic dissection or penetrating aortic ulcer exists. Aggressive control of blood pressure with intensive care unit monitoring has been our initial management. Patients who have involvement of the descending thoracic aorta alone can frequently be managed without surgery in the absence of coexisting aneurysmal dilatation or disease progression. Our experience suggests that a more aggressive approach with early surgery is warranted in patients who have ascending aortic involvement or those who have coexisting aneurysm and intramural hematoma.