Israel J. Jacobowitz

Prevention of Reperfusion Injury of the Ischemic Spinal Cord: Use of Recombinant Superoxide Dismutase

We investigated the effect of recombinant superoxide dismutase, an oxygen free radical scavenger, on the prevention of reperfusion injury of the ischemic spinal cord. Somatosensory evoked potentials (SEPs) were obtained in 23 dogs. Spinal cord ischemia was produced by cross-clamping the descending thoracic aorta just distal to the origin of the left subclavian artery through a left thoracotomy. Mean proximal aortic blood pressure was maintained between 90 and 100 mm Hg by partial exsanguination. Serial SEPs were obtained at 60-second intervals until the SEP disappeared. Aortic cross-clamping was continued for 10 additional minutes after the disappearance of the SEP. In Group 1 (N = 8), no medication was given when the aortic cross-clamp was removed. In Group 2 (N = 8), a bolus of 25,000 units of superoxide dismutase was injected into the proximal aorta prior to removal of the aortic cross-clamp, and was followed by 5,000 units per minute for 10 minutes after release of the cross-clamp. In Group 3 (N = 7), 50,000 units of superoxide dismutase was administered as a bolus prior to removal of the aortic cross-clamp, followed by an additional 10,000 units per minute for 10 minutes as in Group 2. The postoperative neurological status was assessed by Tarlovs criteria. There was no significant difference in aortic cross-clamp time among the three groups. Paraplegia developed in 4 animals in Group 1; the remaining 4 dogs had paraparesis. In Group 2, paraparesis developed in 2 of 8 dogs; the other 6 had no neurological injury. All the animals in Group 3 had complete recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

Internal Mammary Artery Bypass Grafting: Influence on Recurrent Angina and Survival in 2,100 Patients

Internal mammary artery (IMA) bypass grafting to the anterior descending coronary artery was performed in 2,100 patients between January 1978 and July 1986. The average number of additional saphenous vein grafts (SVGs) per patient was 1.8. During the same period, 1,753 patients underwent coronary artery bypass grafting using an SVG (average number of grafts per patient, 3.2). The average patient age was similar: 62.3 years for IMA grafts and 64.7 years for SVGs. Men constituted two thirds of each group. Left ventricular function was impaired (ejection fraction less than 45%) in 1,071 (51%) of IMA grafts and 847 (48.3%) of SVGs. Other aggregate risk factors, ie, elevated blood pressure, diabetes mellitus, previous myocardial infarction, and congestive heart failure, were similar in each group. Operative results and postoperative mortality of the IMA and SVG patients were comparable. However, the long-term probability of cumulative survival and occlusion-free survival were significantly greater and the probability of recurrent angina and reoperative coronary artery bypass grafting were significantly less in IMA graft patients (p less than 0.015). The relative risk of occlusion in an SVG was 4 to 5 times greater than that of the IMA graft. These data indicate that a patent IMA graft to the anterior descending coronary artery protects against recurrent angina and death from cardiac-related causes, and that the IMA should be the conduit of choice.

Analysis of morbidity and mortality in patients 70 years of age and over undergoing isolated coronary artery bypass surgery

With increasing frequency more elderly patients are referred for coronary artery bypass surgery. The operative results of 201 patients 70 years of age and over were compared with the results of 1242 patients under 70 years operated on since 1981. A larger percentage of the elderly patients had triple-vessel disease (66.2% vs 51.0%, p less than 0.001), left main coronary artery obstruction (34.8% vs 16.3%, p less than 0.01), and an ejection fraction of less than or equal to 45% (30.8% vs 21.1%, p less than 0.001). An increase percentage of the patients 70 years of age and over had perioperative myocardial infarction (7.9% vs 4.1%, p less than 0.05), required prolonged ventilatory support (7.9% vs 3.1%, NS), and had major neurologic complications (4.0% vs 1.1%, p less than 0.001). The mortality rate was significantly higher in the elderly patients (5.9% vs 1.9%, p less than 0.01) but did not correlate with degree of coronary artery disease, anginal pattern, or preoperative ventricular function. Only 2 of 12 deaths in the elderly patients were from cardiac causes. This data would suggest that elderly patients have an increased risk for significant cardiac and noncardiac morbidity and mortality following coronary artery bypass surgery and that the higher mortality rate in this age group may be a result of noncardiac organ failure.

Cryopreserved Homologous Saphenous Vein: Early and Late Patency in Coronary Artery Bypass Surgical Procedures

Autologous saphenous vein has proved to be a satisfactory conduit for use in coronary artery bypass grafting. Unfortunately, it is not always available, and substitute material must sometimes be used. When satisfactory autologous veins were not available and the internal mammary arteries were unsuitable, cryopreserved homologous saphenous veins were used in 28 patients. A total of 76 grafts were constructed. Cryopreserved homologous veins were used for 61 grafts, autologous saphenous veins for 11 grafts, and the internal mammary artery for 2 grafts. Coronary angiography was performed 8 to 12 days postoperatively in 16 patients. Of the 31 homografts studied, 8 were occluded (26%), 3 were stenotic (9%), and 20 were normal (65%). The one internal mammary artery and six autologous veins studied were all patent. Six patients underwent late catheterization 6 to 12 months postoperatively. Thirteen homografts were studied at late catheterization: 11 were occluded, 1 was severely stenotic, and 1 was mildly stenotic. At late catheterization, the one internal mammary artery studied was patent, and the one autologous saphenous vein was 95% occluded. Results of both early and late catheterization performed on 18 patients demonstrated that of the 35 homografts studied, 17 (49%) were occluded, 3 (9%) had greater than 70% stenosis, 1 (3%) had mild disease, and 14 (40%) were free of disease. One year follow-up data obtained on 26 patients revealed that 4 patients (15%) died of cardiac causes, 2 patients (8%) died of noncardiac causes, 11 patients (42%) have recurrent angina, and 9 (35%) are asymptomatic. It is concluded that use of cryopreserved homologous saphenous veins for coronary artery bypass grafting should be avoided if at all possible.

Intrathecal perfusion of an oxygenated perfluorocarbon prevents paraplegia after aortic occlusion

A canine model was used to evaluate the effects of continuous intrathecal perfusion of an oxygenated perfluorocarbon emulsion on systemic and cerebral hemodynamics and neurologic outcome after 70 minutes of normothermic aortic occlusion. Twelve mongrel dogs were instrumented to monitor proximal and distal arterial blood pressure, cerebrospinal fluid pressure, spinal cord perfusion pressure, and somatosensory evoked potentials. The intrathecal perfusion apparatus consisted of two perfusing catheters, placed in the intrathecal space through a laminectomy, and a draining catheter percutaneously inserted in the cisterna cerebellomedullaris. The aorta was cross-clamped just distal to the left subclavian artery for 70 minutes. Animals were randomized into two groups: group 1 (n = 6) animals were treated with intrathecal perfusion of saline solution, whereas group 2 (n = 6) animals received oxygenated Fluosol-DA 20%. Data were acquired at baseline, during the cross-clamp period, and after reperfusion. Normothermic Fluosol or saline solution was infused at a rate of 15 mL/min beginning 15 minutes before cross-clamping and continued throughout the ischemic interval. There was no difference in proximal arterial blood pressure (97.2 versus 95.4 mm Hg; p > 0.05) or distal arterial blood pressure (14.6 versus 15.0; p > 0.05) between the two groups throughout the cross-clamp interval. Cerebrospinal fluid pressure rose significantly in both groups with the onset of intrathecal perfusion of either saline solution or Fluosol (7 +/- 1 versus 24 +/- 5 and 8 +/- 1 versus 40 +/- 4 mm Hg, respectively; p < 0.05). The rise in cerebrospinal fluid pressure was sustained throughout the perfusion interval in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Demographic changes in coronary artery bypass surgery and its effect on mortality and morbidity.

Over the past 4-5 years, possibly with the advent of percutaneous transluminal coronary angioplasty (PTCA), there has been a changing patient population for coronary artery bypass surgery (CABS) with a gradual increase in the operative mortality. In an attempt to analyze the changing demographics in patients undergoing CABS and its effect on operative mortality, we analyzed data from 5536 consecutive patients undergoing isolated CABS. There was 4151 patients less than 70 years of age and 1385 patients greater than 70 years. Reoperative CABS procedures were performed in 385 patients, and CABS for post infarction unstable angina pectoris was performed in 578 patients. During the same time period, 2910 patients underwent PTCA. The mean age of bypass patients was 68.5 years with 38% being 70 years or older. The left ventricular ejection fraction in patients undergoing CABS averaged 38%. The average number of bypasses performed was 3.1. In comparison, patients presenting for PTCA were younger (average age 55), had normal ejection fractions (average 55%) and were predominantly treated for single or double vessel disease. The hospital mortality for elective CABS in patients less than 70 years of age was 1.8%, for reoperative CABS 3.6%, for post infarction unstable angina pectoris 4%, and for patients greater than 70 years 8%, for a combined operative mortality of 4.8%. These data suggest that because of the increasing number of elderly patients (greater than 70 years of age), and the increasing number of reoperative CABS cases and acute myocardial infarction patients with unstable angina pectoris presenting for CABS, the operative mortality will continue to rise.

In vitro bursting strength studies of laser-welded tissue and comparison with conventional anastomosis

We compared the mechanical integrity of microvascular anastomoses created with a carbon dioxide (CO2) laser with conventional suture anastomoses. Seventy rat femoral artery segments (35 lased and 35 sutured) were harvested at 1, 24, and 72 hours, and 1, 3, 6, and 12 weeks postoperatively. These segments were subjected to increasingly higher in vitro intraluminal hydrostatic pressures (bursting pressure). Conventionally sutured anastomoses exhibited significantly increased ability (p less than 0.05) to withstand greater bursting pressures than the laser-welded tissue up to 3 weeks postoperatively. After the third postoperative week, the laser anastomoses demonstrated increased bursting pressures compared with the conventional anastomoses. At the end of the 12-week period both groups demonstrated an ability to withstand supraphysiologic pressures in excess of 2000 mm Hg.

Radiation induced cardiac valve disease in a man from Chernobyl.

A young man presented with a new heart murmur. History revealed that the patient was from Ukraine, which was affected by the Chernobyl nuclear plant explosion in 1986. Physical examination revealed murmurs of mitral regurgitation and aortic stenosis. Transesophageal echocardiography revealed severely calcified mitral and calcified tricuspid aortic valves with mitral and aortic regurgitation and aortic stenosis. Following valve replacement surgery, pathologic examination of the valves showed severe dystrophic calcifications and changes suggestive of a chronic inflammatory process such as radiation-induced valve disease. In the absence of another etiology explaining such severe valve disease in a young man, it can only be surmised that heavy radiation exposure from the nuclear plant caused this significant valve damage.

Internal mammary artery bypass: effect on longevity and recurrent angina pectoris in 2900 patients.

Internal mammary artery bypass (IMA) to the anterior descending coronary artery was performed in 2900 patients from January 1978 to December 1987. The average age of the patients was 64 years. Males accounted for 68% (1972 patients) and 82% (2378 patients) were in New York Heart Association (NYHA) class III. Left ventricular function was impaired in 51%. The average number of additional saphenous vein grafts per patient was 1.8. The operative mortality was 1.6%. Mediastinitis occurred in 29 patients (1%). Reoperation for bleeding was necessary in 32 patients (1.1%). Perioperative myocardial infarction (MI) was seen in 58 patients (2%) and neurological complications occurred in 32 patients (1.1%). Repeat coronary angiography was performed in 703 patients (25%) and demonstrated a patency rate of 96% in IMA grafts and 81% in saphenous vein grafts (SVG). Survival at 9 years was 90% from all causes and 95% when noncardiac deaths were excluded. Recurrence of angina occurred in 522 patients (18%) and reoperation was performed in 15 patients (0.5%). During the same time period, 1783 patients underwent coronary artery bypass utilizing a SVG. Survival at 9 years was 78% from all causes and 83% when noncardiac deaths were excluded. Recurrent angina was present in 546 patients (39%). These data suggest that a patent-IMA to the anterior descending protects against recurrent angina and death from cardiac causes and should be the conduit of choice.

Pericardial hernia: an unusual complication of convergent atrial fibrillation ablation.

A 59-year-old woman with highly symptomatic recurrent paroxysmal atrial fibrillation had failed antiarrhythmic therapy and pulmonary vein isolation. Owing to her large left atrial size and failed pulmonary vein isolation, she underwent the convergent atrial fibrillation ablation. A 3-cm subxiphoid incision was made at the central tendon of diaphragm above the liver, medial to the falciform ligament. Through this port, the VisiTrax ablation device (nContact, Inc., Morrisville, NC, USA) was advanced into the pericardial space and ablation was performed at the posterior left atrium and around the pulmonary veins. Subsequently, through an transseptal approach, endocardial lesions were created at the posterior antrum of the left superior pulmonary vein. Bidirectional block was confirmed across all four veins and a right-sided cavotricuspid isthmus line was created. Amiodarone was continued for 3 months. Four months after the procedure, she complained of constant bloating. Physical examination and routine laboratories were normal. Echocardiography showed an echogenic mass anterior to her heart. Computed tomography of her chest confirmed a diaphragmatic hernia with portions of greater omentum and transverse colon extending into the pericardium (Fig.xa01). Laparoscopic hernia repair was performed. Diaphragmatic and pericardial openings were closed with figure of eight sutures and her abdominal symptoms resolved. n n n nFigurexa01: n nCT chest showing diaphragmatic hernia with portions of greater omentum and transverse colon extending into the pericardium. n n n nDiaphragmatic hernia is rare and usually congenital or traumatic [1]. There are few case reports documenting diaphragmatic hernias following a pericardial window, pacemaker placement [2] and coronary artery bypass graft [3]. Being a minimally invasive procedure, the convergent ablation has minimal complications [4]. We have modified our technique to create a more posterior pericardial access site and we have not had any further cases of intrapericardial hernia. Alternatively, routine closure of the diaphragmatic access with a suture may also reduce the possibility of hernia formation.