Sebastian Pagni

Evidence for Improved Cerebral Function After Minimally lnvasive Bypass Surgery

Abstract Background: Neurological impairment is a major cause of morbidity after cardiac surgery and may be associated with occurrence of cerebral microemboli generated during cardiopulmonary bypass (CPB). This study evaluates cerebral dysfunction following coronary artery surgery on‐pump and off‐pump. Methods: Neurological outcome was evaluated in 322 patients with a coronary artery bypass graft (CABG). Conventional CPB was used (on‐pump) in 305 patients and in 17 patients no CPB was used (off‐pump). Intraoperatively, a pulsed‐wave transcranial Doppler with a 2‐MHZ probe measured high‐intensity transient signals (HITS) by ultrasonic insonnation of the middle cerebral artery indicating the presence of emboli within the vessel lumen. Transcranial near‐infrared spectroscopy measured cerebral venous oxygen saturation for adequate perfusion. Postoperatively, all patients were subjected to the antisaccadic eye movement (ASEM) test, a sensitive indicator of neurocognitive deficits secondary to frontal lobe dysfunction. Results: While there was no significant difference in O2 saturation, the number of microemboli HITS generated was significantly higher in the on‐pump group than the off‐pump group. In the off‐pump group, 16 (94%) of 17 patients had perfect scores on the ASEM test, while only 108 (35.4%) of 305 patients achieved a perfect score in the on‐pump group (p < 0.01). Furthermore, while all patients in the off‐pump group achieved at least 90%, 28% (86/305) in the on‐pump group scored “zero” on the ASEM test. Conclusion: Cerebral dysfunction as evidenced by ASEM errors is common following coronary bypass on‐pump, but rare with off‐pump bypass surgery. Cerebral microemboli generated during CPB may account for this difference. (J Card Surg 1998;13:27–31

Anastomotic complications in minimally invasive coronary bypass grafting.

BACKGROUND Anterior wall myocardial revascularization through a left anterior minithoracotomy is an increasingly accepted procedure. Technical failure at the anastomotic site, promoting persistent or recurrent angina, is known to occur and may be underrecognized. This report summarizes the incidence of technical failure in an initial clinical experience and describes potential causes of early postoperative complications. METHODS Between December 1995 and May 1996, 15 patients underwent left internal mammary artery-to-left anterior descending artery revascularization without extracorporeal circulation. The surgical indication was single-vessel coronary disease in all patients. We exposed the left anterior descending artery target site through a 10-cm left anterior fourth space thoracotomy. The fourth costal cartilage was resected and the left internal mammary artery was harvested under direct visualization. Two 4-0 polypropylene sutures snared in tourniquets proximal and distal to the anastomotic site were used to obtain a bloodless field and stabilization of the left anterior descending artery. RESULTS All patients had procedures initially deemed successful based on disappearance of angina or postoperative transthoracic Doppler examination of the internal mammary artery 3 to 5 days postoperatively. However, 3 patients presented with recurrent angina at 2, 6, and 8 weeks. Angiography or direct visualization at operation demonstrated the technical complication (stenosis at the anastomotic site in 2 and snare injury in the native vessel in 1). Two patients required reoperation. CONCLUSIONS Initial results with minimally invasive coronary bypass grafting have generated great enthusiasm worldwide, but there is no consensus on how the procedure should be performed. These results suggest that a nonstabilized anastomosis results in an unacceptable failure rate. Furthermore, sutures encircling the left anterior descending artery should not be used for vessel stabilization as injury of the artery may occur.

ITA versus SVG: a comparison of instantaneous pressure and flow dynamics during competitive flow.

OBJECTIVE Competitive flow from patent native coronary vessels is implicated in the failure of internal thoracic artery (ITA) grafts, but it is not thought to affect saphenous vein graft (SVG) patency. This study examines instantaneous pressure and flow dynamics in left ITA and SVG grafts in competition with a patent left anterior descending (LAD) artery. METHODS SVG (3.0-4.0 mm) and ITA (1.5-2.0 mm) to proximal LAD (2.5-3.0 mm) coronary bypass was performed in 10 mongrel dogs. Flow and pressure were measured in the occluded (No Competition) and opened (Competition) ITA, SVG and LAD. RESULTS The ITA and SVG, when each was the sole inflow to the LAD, provided similar flow as the native LAD. During competitive flow, total LAD flow was preserved and flow in the ITA and SVG were reduced (8.20 +/- 1.25 and 10.00 +/- 1.73 ml/min; P < 0.005). SVG diastolic flow was reduced to 11.52 +/- 2.17 ml min (55.5%); P < 0.003. Flow in the SVG remained predominantly antegrade. In contrast, ITA diastolic flow was reduced more drastically, to 5.37 +/- 1.25 ml/min (80.7%); P < 0.0001. When the ITA was the only inflow to the LAD, there was delay in the LAD pressure wave. This delay disappears during competition due to the large, systolic retrograde flow up the ITA. CONCLUSION The ITA, compared to the SVG, is a longer and narrower conduit with lower levels of flow during competition. Due to a delay in the pressure wave, the ITA flow is retrograde during early systole. Low levels of flow, with a markedly decreased diastolic phase, and the oscillating pattern in systole (retrograde/antegrade) may be poorly tolerated by the ITA endothelium and lead to graft deterioration.

Clinical experience with the video-assisted saphenectomy procedure for coronary bypass operations

BACKGROUND Leg wound complications after saphenectomy are frequent after coronary bypass operations and have a detrimental effect on postoperative quality of life and treatment cost. To reduce morbidity, we evaluated a new technique of video-assisted vein harvest. METHODS Between March 1996 and October 1996, 50 patients had video-assisted saphenectomy (VAS) and 40 patients had the standard open technique (control group). An additional 13 patients had both procedures (hybrid group). Level of pain, edema, and wound complications were evaluated at discharge and at 2, 4, and 6 weeks postoperatively. RESULTS The mean operating time for VAS patients was slightly higher than for control (60.6+/-24.7 minutes versus 53.2+/-21.1 minutes; p > 0.05). The average incision length in VAS patients was 13.8+/-8.8 cm for an average of 3.3 grafts per patient. Three VAS procedures were aborted, two because of time constraints, and one because of bleeding, and a segment of vein was lost to injury. The VAS group had considerably less early postoperative pain than the control group (1.7+/-1.2 versus 4.1+/-1.4 [1 = mild, 10 = severe]; p < 0.005) and edema was similar for both groups. Patients in the hybrid group reported less pain in the VAS-operated leg. Serious wound infection occurred in 4 patients, with 2 patients in the control group requiring reoperation for drainage and flap reconstruction. CONCLUSIONS Based on this initial experience, VAS harvesting, although initially more time consuming, is a rapidly mastered technique, results in shorter overall incision length, and is associated with considerably less postoperative pain than the standard open technique.

Thoracic Aortic Mobile Thrombus: Is There a Role for Early Surgical Intervention?

BACKGROUND The diagnosis of thoracic aortic mobile thrombus (TAMT) is rare and is usually made after debilitating embolic events. The optimal treatment strategy is unknown. We report 14 patients with TAMT and aim to better define the role of early (less than 2 weeks) surgical thrombectomy. METHODS Between February 1996 and February 2010, we treated 14 patients (9 women; aged 32 to 84 years, mean age 51 years) with TAMT. Hypercoagulable disorders or a strong family history of vascular thrombosis, or both, occurred in 9 patients. Diagnosis was made by transesophageal echocardiogram in 6, computed tomography angiography in 7, and digital subtraction angiography in 1. Embolic locations were extremities (n=9), cerebral (n=6), and abdominal (n=6). Aortic thrombi (n=17) locations were ascending/arch (n=7), descending (n=8), and thoracoabdominal (n=2). RESULTS All patients were initially treated with heparin and aspirin. Thoracic aortic thrombectomies were performed in 8 patients within 2 weeks of diagnosis: left thoracotomy (n=5), thoracoabdominal (n=1), and median sternotomy (n=2). Left atrial-femoral bypass was used in 5 patients, cardiopulmonary bypass in 2, and no support in 1. Additional procedures were celiac artery (n=1) and left subclavian artery (n=2) thrombectomies. Procedures for embolic complications were performed in 7 patients before aortic thrombectomy. Operative mortality was 0%, with no recurrent embolic events after 24±16 months. One patient had thrombectomy of the ascending aorta and medical therapy with warfarin and aspirin for a second concurrent small thrombus in the descending aorta. One patient presented with multiorgan failure and died shortly after admission. Six patients treated medically were discharged on a regimen of oral warfarin and aspirin (14±11 months follow-up), with 2 fatal recurrent embolic events within 6 weeks (p=0.09). CONCLUSIONS Thoracic aortic mobile thrombus is rare and is commonly associated with morbid thromboembolic events. In our experience, early surgical aortic thrombectomy had a low operative risk and may prevent fatal recurrent embolic events.

Adaptive-outward and maladaptive-inward arterial remodeling measured by intravascular ultrasound in hyperhomocysteinemia and diabetes.

Background: Coronary artery remodeling implies structural changes in the vessel wall in response to various pathophysiologic conditions. However, the classification of remodeling is unclear. We hypothesized that the adaptive, positive-outward remodeling is a reactive and compensatory response to the stress. The maladaptive negative-inward constrictive remodeling is a passive atherosclerotic condition in which the vessel becomes stiffer. Methods: Patients with atherosclerotic lesions underwent intravascular ultrasound (IVUS) scans. The size of the vessels distal to and proximal to plaques were analyzed by IVUS. Diabetes was created in mice by an intraperitoneal injection of alloxan (65 mg/kg). To reduce remodeling, mice received ciglitazone, an agonist of peroxisome proliferators activated receptor-g (PPARg) in drinking water. After 8 weeks, atherosclerotic vessels were analyzed for collagen and elastin. Results: IVUS data suggest an adaptive coronary arterial remodeling was a positive compensatory response to various pathologic stimuli; for example, with the deposition of atherosclerotic plaque, coronary arterial segments enlarged to maintain luminal area. This phenomenon was commonly observed during the initial phases of the development of atherosclerosis. However, negative coronary artery remodeling, or a decrease in vessel area with the formation of atherosclerotic plaque, was maladaptive and was associated with smoking, hypertension, hyperhomocysteinemia, diabetes mellitus, and also after percutaneous coronary interventions (restenosis). In diabetic mice, there was increased collagen and decreased elastin contents; however, treatment with ciglitazone ameliorated the decrease in elastin contents. Conclusion: Global enlargement of the coronary vascular tree occurs during pressure and volume overload associated with ventricular hypertrophic states such as athletic conditioning, hypertensive heart disease, and dilated cardiomyopathy. On the other hand, maladaptive coronary arterial remodeling occurs in patients with severe deconditioning, diabetes mellitus, after coronary artery bypass surgery, and in some instances, postintervention.

Early and Midterm Outcomes Following Surgery for Acute Type A Aortic Dissection

Surgical repair of acute Type A aortic dissection (AADA) is still associated with high in‐hospital mortality. We evaluated the impact of perioperative risk factors on early and midterm survival.

Serious wound infections after minimally invasive coronary bypass procedures

BACKGROUND Minimally invasive coronary artery bypass grafting has become an increasingly accepted therapy for selected patients with single-vessel coronary artery disease. Reported morbidity has focused on anastomotic problems, but the occurrence of serious wound complications after these procedures has not been well documented. METHODS We reviewed our institutional experience with 35 patients to look for the incidence of serious wound complications. RESULTS Three patients had serious wound problems after minithoracotomy for coronary artery bypass graft procedures. This represents an overall 9% wound morbidity rate and a 100% rate in the obese women. CONCLUSIONS Wound complications at the incision site after minithoracotomy coronary artery bypass graft procedures seem to occur distinctly in obese women with redundant breasts.

Electrical stimulation of cardiomyocytes activates mitochondrial matrix metalloproteinase causing electrical remodeling.

Cardiac arrhythmias, instigated by mechanical and electrical remodeling, are associated with activation of extracellular matrix metalloproteinases (MMPs). However, the connection between intracellular MMPs activation and arrhythmogenesis is not well established. Previously, we determined localization of MMP in the mitochondria using confocal microscopy. We tested the hypothesis that electrical pacing induces the activation of mitochondrial MMP (mtMMP) and is associated with myocyte mechanical dysfunction. Myocytes were isolated and field stimulated at 1 and 4 Hz. Myocyte mechanics and calcium transient was studied using Ion-Optix system. Mitochondrial MMP-9 activation was evaluated using zymography. There was a 25% increase in 1 Hz and 40% increase in 4 Hz stimulation. We observed an increase in mtMMP activation with increase in electrical pacing compared to 0 Hz with a significant increase (p<0.05, n=3). Field stimulation at 4 Hz decreased cell re-lengthening. The levels of calcium transient were reduced with increase in contraction frequency. We conclude that electrical stimulation activates mtMMP-9 that is associated with myocyte mechanical dysfunction.

Clinical Outcome After Triple-Valve Operations in the Modern Era: Are Elderly Patients at Increased Surgical Risk?

BACKGROUND Despite modern advances in surgical care, triple-valve surgery (TVS) remains a challenge and carries a mortality of 10% to 20%. No validated risk score is available for TVS, and the effect of advanced age is unknown. This study examined our results in the modern era with the aim of identifying perioperative predictors of adverse outcomes. METHODS Between 1997 and 2013, 131 patients (mean age, 67.2±13.4 years) underwent TVS at our institution. Sixty-eight patients (51.9%) were aged 70 years and older. The most common etiology for aortic and mitral disease was degenerative (77.1%), rheumatic (10%), and endocarditis or prosthetic-related, or both, in the rest. Tricuspid valve disease was functional in 96%. New York Heart Association functional class III/IV was present in 69.4%, and 24% had had previous cardiac operations. One or more concomitant cardiac procedures were performed in 77 patients (58.8%), including coronary revascularization in 54. All aortic procedures were replacements, 14 patients required a prosthetic root conduit and 7 thoracic aorta replacement. Mitral replacements were used in 55%, repairs in 45%, and 96.2% of tricuspid procedures were repairs. Univariate and multivariate analyses were used to determine predictors of adverse outcomes. RESULTS The 30-day and hospital mortality was 10.6% (n=14). Major complications occurred in 70 (53.4%). Univariate analysis identified New York Heart Association functional class III/IV (p=0.04), preoperative renal failure requiring dialysis (p=0.04), urgent operation (p=0.04), intraaortic balloon pump placement (p=0.02), and postoperative low cardiac output (p<0.0001) as predictors for early death. Proximal aortic operations, urgent operation, and New York Heart Association class IV correlated with increased early mortality (p<0.04) in patients aged 70 and older in addition to their decreased overall survival and decreased likelihood of discharge to home. Overall actuarial survival at 1, 5, and 10 years was 84.5%, 75%, and 45%, respectively. CONCLUSIONS TVS remains a surgical challenge in the modern era. Despite a trend of increasing age and surgical risk, the early mortality rate and long-term survival remain respectable. Advanced age is associated with increased perioperative risk, but age per se should not be a contraindication for TVS.