Mechanisms of valve competency after mitral valve annuloplasty for ischaemic mitral regurgitation using the Geoform ring: insights from three-dimensional echocardiography

AIMS

Left ventricular remodelling leads to functional mitral regurgitation resulting from annular dilatation, leaflet tethering, tenting, and decreased leaflet coaptation. Mitral valve annuloplasty restores valve competency, improving the patient's functional status and ventricular function. This study was designed to evaluate the mechanisms underlying mitral valve competency after the implantation of a Geoform annuloplasty ring using three-dimensional (3D) echocardiography.

METHODS AND RESULTS

Seven patients (mean age of 65 years) with ischaemic mitral regurgitation underwent mitral valve annuloplasty with the Geoform ring and coronary artery bypass surgery. Pre- and post-operative 3D echocardiograms were performed. Following mitral annuloplasty, mitral regurgitation decreased from 3.4+/-0.2 to 0.9+/-0.3 (P-value<0.0001), mitral valve tenting volume from 13+/-1.7 to 3.2+/-0.3 mL (P-value<0.001), annulus area from 12.6+/-1.0 to 3.3+/-0.2 cm2 (P-value<0.0001), valve circumference from 13+/-0.5 to 7.3+/-0.3 cm (P-value<0.0001), septolateral distance from 2.1+/-0.1 to 1.4+/-0.06 cm (P-value<0.01) and intercommissural distance from 3.4+/-0.1 to 2.7+/-0.03 cm (P-value<0.03). There was significant decrease in the septolateral distance at the level of A2-P2 with respect to other regions. These geometric changes were associated with the improvement in the NYHA class from 3.1+/-0.3 to 1.3+/-0.3 (P-value<0.002).

CONCLUSION

The mitral valve annuloplasty with the Geoform ring restores leaflet coaptation and eliminates mitral regurgitation by effectively modifying the mitral annular geometry.

Intestinal Ischemia Complicating Ascending Aortic Dissection: First Things First

Typically acute dissections of the ascending aorta are considered operative emergencies with delays in treatment potentially resulting in considerable morbidity and mortality. However, occasionally associated unstable or poorly defined problems (such as neurologic impairment or end-organ ischemia) may warrant further investigation and possible treatment to facilitate safe aortic repair. We present a case of acute ascending aortic dissection associated with an intra-abdominal vascular and enteric catastrophe that was successfully managed prior to aortic repair.

Mycotic Coronary Artery Aneurysm From Fungal Prosthetic Valve Endocarditis

Two cases of mycotic aneurysms of the left anterior descending coronary artery in patients with fungal prosthetic valve endocarditis are reported. One was managed with exclusion and interposition graft, and the other was managed by aneurysm excision, wide debridement, and distal bypass. The current literature and management strategies are reviewed.

Single-Stage Resection of a Mixed Endometrial Stromal Sarcoma and Smooth Muscle Tumor With Intracardiac and Pulmonary Extension

A case of mixed endometrial stromal sarcoma and smooth muscle cell tumor of the uterus with intravenous extension into the right heart and pulmonary artery is presented. The current literature and diagnostic and therapeutic strategies of pelvic tumors with intravenous extension are reviewed.

The effect of adjuvant perfusion techniques on the incidence of paraplegia after repair of traumatic thoracic aortic transections

OBJECTIVE

To analyze the effect of adjuvant perfusion techniques of the distal aorta on the outcome of traumatic thoracic aortic transections.

PATIENTS AND METHODS

From 1973 to 2004, 72 patients (mean age, 39 years) with thoracic aortic transections arrived alive at the emergency department. Nineteen patients arrived in extremis and underwent emergency operations, 42 patients were stable and underwent diagnostic evaluation before surgery (4 patients experienced aortic rupture during evaluation), and 11 patients presented more than 24 hours after the accident. Sixteen patients died before aortic repair could be performed. Operative repair was possible in 53 patients (46 stable and 7 in extremis). Interposition graft was performed in 47 patients, and primary repair was performed in 6 patients. Morbidity, mortality, and paraplegia rate were analyzed.

RESULTS

Patients in extremis had a mortality rate of 84% (16 of 19), stable patients had a mortality rate of 11% (4 of 38), patients who experienced rupture during evaluation had a mortality rate of 100% (4 of 4), and patients who underwent delayed operation had a mortality rate of 0% (0 of 11). The paraplegia rate with and without adjuvant distal aortic perfusion techniques was 2% (1 of 41 patients) and 33% (4 of 12 patients), respectively (P=.007). Mortality and paraplegia rates were 4% and 4% for partial bypass (n=24), 42% and 33% for the clamp and sew technique (n=12), 0% and 0% for Gott shunt (n=10), and 29% and 0% for full cardiopulmonary bypass (n=7), respectively.

CONCLUSIONS

Although thoracic aortic transections remain a highly lethal injury, hemodynamically stable patients have a low operative mortality. Spinal cord injury is decreased by the use of adjuvant perfusion techniques that maintain distal aortic perfusion during cross-clamping of the aorta.

Mitral and tricuspid valve repair in patients with previous mediastinal radiation therapy

BACKGROUND

The purpose of this study was to evaluate outcomes of mitral and tricuspid valve repair after mediastinal radiation therapy.

METHODS

From 1976 to 2001, 22 patients (mean age 61 +/- 14 years) underwent mitral (n = 14), tricuspid (n = 6), or both (n = 2) valve repairs 15 +/- 9 years after mediastinal radiation therapy. Concomitant procedures included coronary artery bypass graft, 11 patients; valve replacement, 6 patients (4 aortic, 3 mitral, 1 tricuspid, and 1 pulmonary); and pericardiectomy, 4 patients.

RESULTS

Total follow-up was 82.5 patient-years (mean 3.7 +/- 3.3 years). Early mortality was 3 patients. There were 7 late deaths, 4 of which were of cardiovascular origin. Of the 19 early survivors, 2 required subsequent valve replacements, and 1 required cardiac transplantation 3.4 +/- 2.8 years after valve repair. One patient died after reoperation. In 4 patients who did not undergo reoperation, echocardiographic examinations showed progressive deterioration of their repaired valve function. Overall survival, freedom from cardiac death, and freedom from valve reoperation or cardiac transplantation at 5 years for early survivors was 66%, 85%, and 88%, respectively. New York Heart Association functional class at follow-up was I or II in 8 of the 12 late survivors.

CONCLUSIONS

Functional status was good in two-thirds of late survivors. However, severe dysfunction of the repaired valve developed in 32% of early survivors and 16% required further surgery. Valve repair is technically feasible in selected patients after mediastinal radiation therapy; however, the limited durability of repairs after mediastinal radiation in this series suggests that valve replacement might be preferable.

Selective management of intrathoracic anastomotic leak after esophagectomy

OBJECTIVE

We sought to analyze our experience with management of intrathoracic anastomotic leak after esophagectomy.

METHODS

All patients who had intrathoracic anastomotic leaks after esophagectomy were reviewed. Management and factors affecting outcome were analyzed.

RESULTS

From March 1993 through February 2003, 761 patients had esophagectomy with intrathoracic anastomosis at our institution. Forty-eight (6.3%) patients had an anastomotic leak; one refused authorization to review his medical record and was excluded from further analysis. Twenty-four (51.1%) patients had a contained leak. Twenty-seven (57.4%) patients were managed nonoperatively. Twenty (42.6%) patients required surgical intervention that included primary anastomotic repair in 14 patients, reinforcement of the anastomosis with viable tissue in 6 patients, and esophageal diversion in 2 patients. A single reoperation was done in 15 patients, and 5 patients had 2 reoperations. Median hospitalization in the reoperative group was 31 days (range, 15-97 days) and 20 days (range, 10-42 days) in the nonoperative group ( P = .0037). Four (8.5%) patients died. Cause of death was sepsis in 2 patients and multiorgan failure and myocardial infarction in 1 patient each. At follow-up (median, 8 months; range, 1-120 months), 10 (58.8%) patients in the reoperative group were eating a normal diet and 5 (29.4%) patients required at least one dilatation compared with 20 (76.9%) patients in the nonoperative group who were eating a normal diet and 9 (34.6%) who required at least one dilatation. A noncontained leak had an adverse effect on long-term survival ( P = .04).

CONCLUSION

Intrathoracic anastomotic leak after esophagectomy is associated with significant morbidity and mortality. Contained leaks often can be managed nonoperatively. When surgical management is required, esophagogastric continuity can often be maintained in the majority of patients. Long-term functional results are satisfactory and similar in both the reoperative and nonoperative groups. However, a noncontained leak adversely affected long-term survival.

Selective management of intrathoracic anastomotic leak after esophagectomy

OBJECTIVE

We sought to analyze our experience with management of intrathoracic anastomotic leak after esophagectomy.

METHODS

All patients who had intrathoracic anastomotic leaks after esophagectomy were reviewed. Management and factors affecting outcome were analyzed.

RESULTS

From March 1993 through February 2003, 761 patients had esophagectomy with intrathoracic anastomosis at our institution. Forty-eight (6.3%) patients had an anastomotic leak; one refused authorization to review his medical record and was excluded from further analysis. Twenty-four (51.1%) patients had a contained leak. Twenty-seven (57.4%) patients were managed nonoperatively. Twenty (42.6%) patients required surgical intervention that included primary anastomotic repair in 14 patients, reinforcement of the anastomosis with viable tissue in 6 patients, and esophageal diversion in 2 patients. A single reoperation was done in 15 patients, and 5 patients had 2 reoperations. Median hospitalization in the reoperative group was 31 days (range, 15-97 days) and 20 days (range, 10-42 days) in the nonoperative group ( P = .0037). Four (8.5%) patients died. Cause of death was sepsis in 2 patients and multiorgan failure and myocardial infarction in 1 patient each. At follow-up (median, 8 months; range, 1-120 months), 10 (58.8%) patients in the reoperative group were eating a normal diet and 5 (29.4%) patients required at least one dilatation compared with 20 (76.9%) patients in the nonoperative group who were eating a normal diet and 9 (34.6%) who required at least one dilatation. A noncontained leak had an adverse effect on long-term survival ( P = .04).

CONCLUSION

Intrathoracic anastomotic leak after esophagectomy is associated with significant morbidity and mortality. Contained leaks often can be managed nonoperatively. When surgical management is required, esophagogastric continuity can often be maintained in the majority of patients. Long-term functional results are satisfactory and similar in both the reoperative and nonoperative groups. However, a noncontained leak adversely affected long-term survival.

Lung Abscess Due to Retained Gallstones With an Adenocarcinoma

We describe a patient who had a right lower lobe mass containing calcifications consistent with gallstones develop 3(1)/(2) years after laparoscopic cholecystectomy. Thoracotomy revealed a chronic abscess containing pigmented gallstones and an adjacent area of bronchoalveolar adenocarcinoma involving both N1 and N2 lymph nodes.

Thoracic surgical operations in patients enrolled in a computed tomographic screening trial

OBJECTIVE

Screening for lung cancer with computed tomography may detect cancers at an earlier stage but may also result in overdiagnosis. We reviewed the thoracic surgical operations performed on patients enrolled in our computed tomographic screening program.

METHODS

From January 1999 through December 2002, screening computed tomography for lung cancer was performed annually on 1520 participants. All participants were at least 50 years old and smoked more than 20 pack/y. We found 3130 indeterminate pulmonary nodules in 1112 participants (73%). Fifty-five participants (3.6%) underwent 60 thoracic operations for a variety of indications. The medical records of these 55 patients were reviewed.

RESULTS

Indications for operation included suspicious pulmonary nodules, mediastinal adenopathy, and a spontaneous pneumothorax. Operations performed included a lobectomy in 37 cases, wedge resection in 11, segmentectomy in 6, video-assisted thoracoscopic surgical talc pleurodesis in 1, bilobectomy in 2, mediastinoscopy in 2, and anterior mediastinotomy in 1. Benign disease was found in 10 patients (18.1%), and lung cancer was found in 45 (81.9%), 2 of whom had metachronous lung cancers. Cell types were adenocarcinoma in 15 cancers, bronchioloalveolar cell carcinoma in 13, squamous cell in 13, carcinoid in 2, small cell in 2, and large cell and undifferentiated non-small cell in 1 case each. Twenty-eight cancers were classified as stage IA, 4 as IB, 4 as IIA, 1 as IIB, 4 as IIIA, 3 as IIIB, 1 as IV, and 2 as limited small cell carcinoma. Complications occurred in 27% of patients. Operative mortality was 1.7%.

CONCLUSION

Computed tomographic screening finds a large number of indeterminate pulmonary nodules in smokers 50 years old or older, most of which are observed and not operated on. Although 47 cancers were detected thus far in this highly selected group of patients, this represents only 1.5% of the pulmonary nodules identified.

Is there a role for the left ventricle apical-aortic conduit for acquired aortic stenosis?

BACKGROUND AND AIM OF THE STUDY

Aortic valve replacement (AVR) in patients with a heavily calcified ascending aorta and aortic root, or with conditions that preclude a median sternotomy, poses a formidable challenge. A left ventricle apical-aortic conduit (AAC) is an alternative in these situations. Herein, the authors' experience with AAC in adult patients with acquired aortic stenosis is reported.

METHODS

Between 1995 and 2003, 13 patients (mean age 71 years) underwent AAC for severe symptomatic aortic stenosis (mean valve area 0.65 +/- 0.02 cm2). Indications for AAC were heavily calcified ascending aorta and aortic root (n = 5), patent retrosternal mammary grafts (n = 4), calcified ascending aorta and aortic root plus patent retrosternal mammary graft (n = 1), retrosternal colonic interposition (n = 1) and multiple previous sternotomies (n = 2). Seven patients had previous coronary artery bypass grafting (CABG). The mean preoperative left ventricular ejection fraction was 50 +/- 4%.

RESULTS

AAC were performed under cardiopulmonary bypass through a left thoracotomy (n = 10), median sternotomy (n = 2) or bilateral thoracotomy (n = 1). Hearts were kept beating (n = 5) or fibrillated (n = 7). Circulatory arrest was used in one patient. Composite Dacron conduits with biological (n = 6), mechanical (n = 4) or homograft (n = 2) valves were used. Distal anastomoses were performed in the descending thoracic aorta (n = 12) or in the left iliac artery (n = 1). Two patients underwent simultaneous CABG. Three patients died in-hospital from ventricular failure (n = 1), intravascular thrombosis (n = 1) and multi-organ failure (n = 1). The mean hospital stay was 26 days. Complications included respiratory failure requiring tracheostomy (n = 2), stroke (n = 1) and re-exploration for bleeding (n = 2). At a mean follow up of 2.1 years, there have been four late deaths; causes of death were congestive heart failure (n = 2), ischemic cardiomyopathy (n = 1) and cancer (n = 1).

CONCLUSION

AAC provides an acceptable alternative to AVR in selected patients who are at exceedingly high risk for the standard procedure.

Giant papillary fibroelastoma of the right atrium: an unusual presentation

Papillary fibroelastomas are small tumors of the valvular endocardium with a propensity to embolize. Fibroelastomas originating in the nonvalvular endocardium are rare. We report a giant papillary fibroelastoma of the right atrial septum presenting with hemodynamic compromise that resolved after surgical excision. The current literature and the diagnostic and therapeutic strategies are reviewed.

Ischemic preconditioning improves mitochondrial tolerance to experimental calcium overload

BACKGROUND

Ca(2+) overload leads to mitochondrial uncoupling, decreased ATP synthesis, and myocardial dysfunction. Pharmacologically opening of mitochondrial K(ATP) channels decreases mitochondrial Ca(2+) uptake, improving mitochondrial function during Ca(2+) overload. Ischemic preconditioning (IPC), by activating mitochondrial K(ATP) channels, may attenuate mitochondrial Ca(2+) overload and improve mitochondrial function during reperfusion. The purpose of these experiments was to study the effect of IPC (1) on mitochondrial function and (2) on mitochondrial tolerance to experimental Ca(2+) overload.

METHODS

Rat hearts (n = 6/group) were subjected to (a) 30 min of equilibration, 25 min of ischemia, and 30 min of reperfusion (Control) or (b) two 5-min episodes of ischemic preconditioning, 25 min of ischemia, and 30 min of reperfusion (IPC). Developed pressure (DP) was measured. Heart mitochondria were isolated at end-Equilibration (end-EQ) and at end-Reperfusion (end-RP). Mitochondrial respiratory function (state 2, oxygen consumption with substrate only; state 3, oxygen consumption stimulated by ADP; state 4, oxygen consumption after cessation of ADP phosphorylation; respiratory control index (RCI, state 3/state 4); rate of oxidative phosphorylation (ADP/Deltat), and ADP:O ratio) was measured with polarography using alpha-ketoglutarate as a substrate in the presence of different Ca(2+) concentrations (0 to 5 x 10(-7) M) to simulate Ca(2+) overload.

RESULTS

IPC improved DP at end-RP. IPC did not improve preischemic mitochondrial respiratory function or preischemic mitochondrial response to Ca(2+) loading. IPC improved state 3, ADP/Deltat, and RCI during RP. Low Ca(2+) levels (0.5 and 1 x 10(-7) M) stimulated mitochondrial function in both groups predominantly in IPC. The Control group showed evidence of mitochondrial uncoupling at lower Ca(2+) concentrations (1 x 10(-7) M). IPC preserved state 3 at high Ca(2+) concentrations.

CONCLUSIONS

The cardioprotective effect of IPC results, in part, from preserving mitochondrial function during reperfusion and increasing mitochondrial tolerance to Ca(2+) loading at end-RP. Activation of mitochondrial K(ATP) channels by IPC and their improvement in Ca(2+) homeostasis during RP may be the mechanism underlying this protection.

Mitochondrial function during ischemic preconditioning

Background. Ischemic preconditioning (IPC) protects the myocardium from ischemia reperfusion injury. The effect of IPC on the mitochondria is not well known. However, one of the mechanisms postulated in IPC (the opening of the mitochondrial K(ATP) channels) is likely to result in changes in mitochondrial function. Therefore, the purpose of this study was to determine the effect of IPC on mitochondrial function during ischemia reperfusion. Methods. Isolated rat hearts (n = 6/group) were subjected to (1) 30 minutes of equilibration, 25 minutes of ischemia, and 30 minutes of reperfusion (RP) (control group) or (2) 10 minutes of equilibration, two-5 minute episodes of IPC (each followed by 5 minutes of re-equilibration), 25 minutes of ischemia, and 30 minutes of RP (IPC group). Left ventricular rate pressure product (RPP) was measured. At end-equilibration (end-EQ) and at end-reperfusion (end-RP) mitochondria were isolated. Mitochondrial respiratory function (state 2, 3, and 4), respiratory control index (RCI), rate of oxidative phosphorylation (ADP/Delta t), and ADP:O ratio were measured by polarography with the use of NADH- or FADH-dependent substrates. Results. IPC improved recovery of RPP at end-RP (72% +/- 5% in IPC vs 30% +/- 4% in control, P <.05). Ischemia reperfusion (IR) decreased state 3, ADP/Delta t, and RCI in both groups compared with end-EQ. IPC improved state 3 (47 +/- 3 in IPC vs 37 +/- 2 ng-atoms O/min/mg protein in control), ADP/Delta t (17 +/- 1 in IPC vs 13 +/- 1 nmol/s/mg protein in control), and RCI (3.7 +/- 0.1 in IPC vs 2.1 +/- 0.2 in control) at end-RP compared with control with the use of NADH-dependent substrate (P <.05 vs control). IPC also improved state 3 (85 +/- 6 in IPC vs 71 +/- 4 ng-atoms O/min/mg protein in control), ADP/Delta t (18 +/- 2 in IPC vs 12 +/- 1 nmol/s/mg protein in control), RCI (2 +/- 0.1 in IPC vs 1.5 +/- 0.1 in control), and ADP:O ratios (1.4 +/- 0.04 in IPC vs 1.7 +/- 0.09 in control) at end-RP compared with control with the use of FADH-dependent substrate (P <.05 vs control). Conclusions. The cardioprotective effects of IPC can be attributed at least in part to the preservation of mitochondrial function during reperfusion.

Effect of coenzyme Q10 supplementation on mitochondrial function after myocardial ischemia reperfusion

BACKGROUND

Coenzyme Q10 (CoQ10) protects myocardium from ischemia-reperfusion (IR) injury as evidenced by improved recovery of mechanical function, ATP, and phosphocreatine during reperfusion. This protection may result from CoQ10's bioenergetic effects on the mitochondria, from its antioxidant properties, or both. The purpose of this study was to elucidate the effects of CoQ10 supplementation on mitochondrial function during myocardial ischemia-reperfusion using an isolated mitochondrial preparation.

METHODS

Isolated hearts (n = 6/group) from rats pretreated with liposomal CoQ10 (10 mg/kg iv, CoQ10), vehicle (liposomal only, Vehicle), or saline (Saline) 30 min before the experiments were subjected to 15 min of equilibration (EQ), 25 min of ischemia (I), and 40 min of reperfusion (RP). Left ventricular-developed pressure (DP) was measured. Mitochondria were isolated at end-equilibration (end-EQ), at end-ischemia (end-I), and at end-reperfusion (end-RP). Mitochondrial respiratory function (State 2, 3, and 4, respiratory control index (RCI, ratio of State 3 to 4), and ADP:O ratio) was measured by polarography using NADH (alpha-ketoglutarate, alpha-KG)- or FADH (succinate, SA)-dependent substrates.

RESULTS

CoQ10 improved recovery of DP at end-RP (67 +/- 11% in CoQ10 vs 47 +/- 5% in Vehicle and 50 +/- 11% in Saline, P < 0.05 vs Vehicle and Saline). CoQ10 did not change preischemic mitochondrial function. IR decreased State 3 and RCI in all groups using either substrate. CoQ10 had no effect in the mitochondrial oxidation of alpha-KG at end-I. CoQ10 improved State 3 at end-I when SA was used (167 +/- 21 in CoQ10 vs 120 +/- 10 in Saline and 111 +/- 10 ng-atoms O/min/mg protein in Vehicle, P < 0.05). Using alpha-KG as a substrate, CoQ10 improved RCI at end-RP (4.2 +/- 0.2 in CoQ10 vs 3.2 +/- 0.2 in Saline and 3.0 +/- 0.3 in Vehicle, P < 0.05). Using SA, CoQ10 improved State 3 (181 +/- 10 in CoQ10 vs 142 +/- 9 in Saline and 140 +/- 12 ng-atoms O/min/mg protein in Vehicle, P < 0.05) and RCI (2.21 +/- 0.06 in CoQ10 vs 1.85 +/- 0.11 in Saline and 1.72 +/- 0.08 in Vehicle, P < 0.05) at end-RP.

CONCLUSIONS

The cardioprotective effects of CoQ10 can be attributed to the preservation of mitochondrial function during reperfusion as evidenced by improved FADH-dependent oxidation.

Opening of potassium channels protects mitochondrial function from calcium overload

Ischemic preconditioning (IPC) protects myocardium from ischemia reperfusion injury by activating mitochondrial K(ATP) channels. However, the mechanism underlying the protective effect of K(ATP) channel activation has not been elucidated. It has been suggested that activation of mitochondrial K(ATP) channels may prevent mitochondrial dysfunction associated with Ca(2+) overload during reperfusion. The purpose of this experiment was to study, in an isolated mitochondrial preparation, the effects of mitochondrial K(ATP) channel opening on mitochondrial function and to determine whether it protects mitochondria form Ca(2+) overload. Mitochondria (mito) were isolated from rat hearts by differential centrifugation (n = 5/group). Mito respiratory function was measured by polarography without (CONTROL) or with a potassium channel opener (PINACIDIL, 100 microM). Different Ca(2+) concentrations (0 to 5 x 10(-7) M) were used to simulate the effect of Ca(2+) overload; state 2, mito oxygen consumption with substrate only; state 3, oxygen consumption stimulated by ADP; state 4, oxygen consumption after cessation of ADP phosphorylation; respiratory control index (RCI: ratio of state 3 to state 4); rate of oxidative phosphorylation (ADP/Deltat); and ADP:O ratio were measured. PINACIDIL increased state 2 respiration and decreased RCI compared to CONTROL. Low Ca(2+) concentrations stimulated state 2 and state 4 respiration and decreased RCI and ADP:O ratios. High Ca(2+) concentrations increased state 2 and state 4 respiration and further decreased RCI, state 3, and ADP/Deltat. PINACIDIL improved state 3, ADP/Deltat, and RCI at high Ca(2+) concentrations compared to CONTROL. Pinacidil depolarized inner mitochondrial membrane, as evidenced by decreased RCI and increased state 2 at baseline. Depolarization may decrease Ca(2+) influx into mito, protecting mito from Ca(2+) overload, as evidenced by improved state 3 and RCI at high Ca(2+) concentrations. The myocardial protective effects resulting from activating K(ATP) channels either pharmacologically or by IPC may be the result of protecting mito from Ca(2+) overload.

Uniform safety of beating heart surgery using the octopus tissue stabilization system

BACKGROUND AND PURPOSE

Minimally invasive coronary artery bypass grafting (CABG) has been facilitated by the introduction of the Octopus Tissue Stabilization system (OTS). OTS improves exposure immobilizing the heart with minimal hemodynamic effects allowing multivessels off cardiopulmonary bypass (CPB) CABG. The purpose of this study was to compare the utilization and clinical outcome of the OTS in three geographically distinct centers.

METHODS

239 patients who underwent OTS-CABG at Allegheny University Hospital/Medical College of Pennsylvania, Harrisburg Hospital, and Park Nicollet Clinic/HealthSystem Minnesota were reviewed. Age, acuity of patients, and number and type of vessels bypassed were recorded. Complications, mortality, length of hospital stay, incidence of conversion to CPB and blood transfusions, and operating room costs were compared to risk matched control patients who underwent CPB CABG during the same period.

RESULTS

Results were similar in all three centers. The average age was 62.3 years. Emergent operation was necessary in 7%-10% of patients, the operations averaged 1.8 grafts/patient. Arteries bypassed were LAD, DIAG, OM, RCA, PDA, and RPLB. There were 96% of operations completed without CPB. Morbidity was low (12%). Atrial fibrillation and blood transfusion rate were decreased. Mortality was 0 compared with a predicted mortality of 1.6%. Hospital length of stay was shorter and operating room costs were 61% lower.

CONCLUSIONS

OTS provides predictable reproducible immobilization allowing the performance of single and multiple off-pump CABG to almost all coronary branches with minimal morbidity and decreased costs in a variety of patients. Similar findings from three different centers suggests that these results are easily reproducible.

Bioenergetic effect of liposomal coenzyme Q10 on myocardial ischemia reperfusion injury

The antioxidant and bioenergetic effects of CoQ10 are well known but its clinical utility is limited by the requirement for enteral administration. A newly developed liposomal CoQ10 (CoQ) is water soluble and capable of intravenous administration. The purpose of this study is to determine the mechanism by which acute administration CoQ protects myocardium from reperfusion (Rp) injury. Rats were pretreated with CoQ 10 mg/kg i.v. 30 min prior to the experiment. Control rats were pretreated with liposome only. Hearts were excised and subjected to equilibration, 25 min of normothermic ischemia and 40 min of Rp on a Langendorff apparatus. At end Rp, CoQ hearts recovered 74 +/- 5% of their DP vs. 50 +/- 9% in control (p < 0.05). Aerobic efficiency was maintained (0.66 +/- 0.02 vs. control, 0.5 +/- 0.04, p < 0.003) and CoQ hearts lost less CK activity vs. control (p < 0.02). PCr and ATP were higher than control (p < 0.05, 0.02, respectively). Results show that i.v. CoQ improves recovery of function, aerobic efficiency, CK activity, and recovery of PCr and ATP after Rp. This suggests that acute administration of liposomal CoQ improves myocardial tolerance to I/R via its role as an antioxidant as well as improving oxygen utilization and high energy phosphate production.

Acute administration of liposomal coenzyme Q10 increases myocardial tissue levels and improves tolerance to ischemia reperfusion injury

The antioxidant and bioenergetic effects of CoQ10 (CoQ) suggest it might be ideal therapy for acute myocardial ischemia. Its utility is limited by the requirement for enteral administration. This study related the administration of a new liposomal suspension of CoQ given intravenously to (1) serum and myocardial [CoQ] and (2) recovery of function, myocardial efficiency, and oxidant injury after cardiac ischemia and reperfusion (I/R). Rats (n = 8/group) were given liposomal CoQ 10 mg/kg iv or placebo (Control), 15 min (C-15), 30 min (C-30), and 60 min (C-60) before (1) measurement of serum and myocardial CoQ or (2) Langendorff perfusion of hearts subjected to 15 min equilibration, 25 min ischemia (37 degrees C), and 40 min reperfusion (RP). Developed pressure (DP) was measured via an intraventricular balloon and coronary flow was measured by a digital flow meter. Myocardial efficiency was defined as DP/MVO2 where MVO2 = microl O2 consumed/min/gram LV. At end RP hearts were assayed for CK, an oxidant sensitive enzyme. Maximum preischemic CoQ levels in serum and myocardium occurred 15 and 30 min after administration, respectively. At end reperfusion, C-30 hearts improved the most, recovering 75 +/- 4% of their preischemic DP while Control recovered only 52 +/- 6% (P < 0.03) as well as maintaining better myocardial efficiency (0.69 +/- 0.02 vs Control, 0.43 +/- 0.05) (P < 0.001). C-15, C-30, and C-60 groups all lost less CK activity after RP vs Control (P < 0.04).

CONCLUSION

(1) Serum and myocardial levels of CoQ can be raised acutely by iv liposomal CoQ. (2) Myocardial CoQ levels correlate best with I/R protection. (3) Acute iv CoQ improves function and efficiency and decreases oxidant injury after I/R. Intravenous CoQ may be effective clinically for acute cardiac ischemic syndromes.

Pyruvate improves myocardial tolerance to reperfusion injury by acting as an antioxidant: a chemiluminescence study

BACKGROUND

There is indirect evidence that pyruvate improves myocardial tolerance to ischemia by scavenging oxygen radicals during reperfusion. The objectives of this study were to evaluate (1) lucigenin-enhanced chemiluminescence (LEC) as a method to measure oxygen radical (OR) production in vitro and in vivo and (2) the antioxidant effect of pyruvate during myocardial reperfusion.

METHODS

LEC was measured in vitro by adding to lucigenin (1) increasing concentrations of H2O2, (2) H2O2 and different concentrations of catalase, and (3) H2O2 plus pyruvate. Isolated rat hearts perfused with Krebs Henseleit-Lucigenin inside a chemiluminescence chamber were subjected to equilibration, ischemia, and reperfusion without (control) or with pyruvate. Developed pressure, contractility, compliance, and chemiluminescence were recorded.

RESULTS

In vitro, LEC directly correlated with H2O2 concentrations (r2 = 0.997) and decreased in the presence of catalase or pyruvate. During myocardial reperfusion there was a surge of chemiluminescence that peaked at 4 minutes. Pyruvate decreased the initial reperfusion peak (9.8 +/- 0.3 x 10(3) cpm in pyruvate group vs 12.4 +/- 0.9 x 10(3) cpm in control; p < 0.05) and the total amount of chemiluminescence generated during reperfusion (65.7 +/- 12 x 10(3) in pyruvate group vs 117.1 +/- 8.2 x 10(3) counts in control; p < 0.05). Pyruvate improved recovery of function after ischemia reperfusion.

CONCLUSIONS

LEC is a sensitive indicator of H2O2 concentrations and can evaluate the effect of antioxidants in vitro. It is a continuous, sensitive, and direct measurement of OR production in vivo. LEC is ideal for the evaluation of antioxidant interventions and provides direct evidence that pyruvate acts as an antioxidant while improving myocardial function during reperfusion.

The mechanisms of coenzyme Q10 as therapy for myocardial ischemia reperfusion injury

It has been hypothesized that CoQ10 (CoQ) pretreatment protects myocardium from ischemia reperfusion (I/R) injury by its ability to increase aerobic energy production as well as its activity as an antioxidant. Isolated hearts from rats pretreated with either CoQ 20 mg/kg i.m. and 10 mg/kg i.p. or vehicle 24 and 2 h prior to the experiment, were subjected to 15 min of equilibration (EQ), 25 min of ischemia, and 40 min of reperfusion (RP). Developed pressure, +/-dp/dt, myocardial oxygen consumption, and myocardial aerobic efficiency (DP/MVO2) were measured. 31P NMR spectroscopy was used to determine ATP and PCr concentrations. Lucigenin-enhanced chemiluminescence of the coronary sinus effluent was utilized to determine oxidative stress through the protocol. CoQ pretreatment improved myocardial function after ischemia reperfusion. CoQ pretreatment improved tolerance to myocardial ischemia reperfusion injury by its ability to increase aerobic energy production, and by preserving myocardial aerobic efficiency during reperfusion. Furthermore, the oxidative burst during RP was diminished with CoQ. Similarly it was hypothesized that CoQ protected coronary vascular reactivity after I/R via an antioxidant mechanism. Utilizing a newly developed lyposomal CoQ preparation given i.v. 15 min prior to ischemia, ischemia reperfusion was carried out on Langendorff apparatus as previously described. Just prior to ischemia and after RP, hearts were challenged with bradykinin (BK) and sodium nitroprusside (SNP) and change in coronary flow was measured. CoQ pretreatment protected endothelial-dependent and endothelial-independent vasodilation after I/R. We conclude that CoQ pretreatment protects coronary vascular reactivity after I/R via OH radical scavenger action.

Ischemic preconditioning decreases oxidative stress during reperfusion: a chemiluminescence study

The mechanism responsible for ischemic preconditioning (IPC) is still unknown but may involve the induction of antioxidant enzymes decreasing oxidative stress during subsequent periods of ischemia (I) and reperfusion (RP). The purpose of this study was to determine whether, in fact, an antioxidant mechanism is involved in the protection afforded by IPC. Lucigenin-enhanced chemiluminescence (LEC), a direct, continuous, nondestructive, on-line method was used to monitor the net amount of free oxygen radicals (FOR) produced during perfusion of rat hearts. Isolated rat hearts were perfused inside a chemiluminescence chamber with lucigenin (1 x 10(-5) M) and subjected to either: (a) 80 min of equilibration (EQ80 group, n = 6), (b) 15 min of EQ, 2 min of IPC, 10 min of reequilibration (REQ), 25 min of I, and 28 min of RP (IPC group, n = 8), or (c) 27 min of EQ, 25 min of I, and 28 min of RP (CTRL, n = 7). Chemiluminescence was measured as counts per minute (cpm) and expressed as %EQ15 (mean +/- SEM). Paired and nonpaired t tests were used for statistical evaluation. EQ80 showed no changes in oxidative stress throughout perfusion (4.5 +/- 0.2 x 10(3) cpm at EQ15 vs 5.1 +/- 0.5 x 10(3) cpm at EQ80, P = NS). During REQ (after IPC) there was a surge of chemiluminescence in IPC hearts compared with CTRL (130 +/- 8% vs 108 +/- 4%, P < 0.05). During reperfusion there was a surge of chemiluminescence in CTRL hearts that was diminished in the IPC hearts (550 +/- 50% vs 380 +/- 50% in IPC, P < 0.05). We conclude that: (1) IPC induces an oxidative stress generating FOR during REQ, (2) IPC decreases the initial FOR burst during RP. We speculate that IPC increases cellular antioxidant defenses which result in decreased oxidative stress during early RP.

Coenzyme Q10 protects coronary endothelial function from ischemia reperfusion injury via an antioxidant effect

BACKGROUND

Cardiac ischemia reperfusion (I/R) injury causes coronary vascular dysfunction. Coenzyme Q10 (CoQ), which preserves cardiac mechanical function after I/R, recently has been recognized as a free radical scavenger. We hypothesized that CoQ protects coronary vascular reactivity after I/R via an antioxidant mechanism.

METHODS

Rats were pretreated with either CoQ (20 mg/kg intramuscular and 10 mg/kg intraperitoneal [CoQ group]) or a vehicle (Control) before the experiment. Isolated perfused rat hearts were subjected to 25 minutes of global normothermic ischemia and 40 minutes of reperfusion. The reperfusion-induced oxidative burst was directly assessed by lucigenin enhanced chemiluminescence. Coronary flow was measured at equilibration and after reperfusion with or without bradykinin, an endothelium-dependent vasodilator, and sodium nitroprusside (SNP), an endothelium-independent vasodilator. The effect of intracoronary infusion of hydrogen peroxide (H2O2 0.1 mumol/gm body weight given over 5 minutes), simulating the free radical burst after I/R, also was evaluated.

RESULTS

I/R decreased the bradykinin-induced change in coronary flow (-5% +/- 4% versus 26% +/- 3% at equilibration; p < 0.05) and the SNP-induced change (+20% +/- 6% versus +56% +/- 5% at equilibration; p < 0.05). The coronary vasculature after H2O2 infusion revealed a similar loss in vasodilatory responsiveness (+4% +/- 4% in response to bradykinin, +35% +/- 8% in response to SNP; p < 0.05 versus equilibration). Pretreatment with CoQ improved BK-induced vasorelaxation after I/R (+12% +/- 2%; p < 0.05 versus control I/R) or H2O2 infusion (18% +/- 4%; p < 0.05 versus control I/R) but failed to improve SNP-induced vasorelaxation. The CoQ pretreatment decreased the I/R-induced maximal free radical burst (9.3 +/- 0.8 x 10(3) cpm versus 11.5 +/- 1.1 x 10(3) cpm; p < 0.05) during the early period of reperfusion.

CONCLUSIONS

Endothelium-dependent vasorelaxation is more sensitive than endothelium-independent relaxation to I/R injury. Via a direct antioxidant effect, CoQ preserved endothelium-dependent vasorelaxation by improving tolerance to I/R injury.

Elucidation of a tripartite mechanism underlying the improvement in cardiac tolerance to ischemia by coenzyme Q10 pretreatment

Coenzyme Q10, which is involved in mitochondrial adenosine triphosphate production, is also a powerful antioxidant. We hypothesize that coenzyme Q10 pretreatment protects myocardium from ischemia reperfusion injury both by its ability to increase aerobic energy production and by protecting creatine kinase from oxidative inactivation during reperfusion. Isolated hearts (six per group) from rats pretreated with either coenzyme Q10, 20 mg/kg intramuscularly and 10 mg/kg intraperitoneally (treatment) or vehicle only (control) 24 and 2 hours before the experiment were subjected to 15 minutes of equilibration, 25 minutes of ischemia, and 40 minutes of reperfusion. Developed pressure, contractility, compliance, myocardial oxygen consumption, and myocardial aerobic efficiency were measured. Phosphorus 31 nuclear magnetic resonance (31P-NMR) spectroscopy was used to determine adenosine triphosphate and phosphocreatine concentrations as a percentage of a methylene diphosphonic acid standard. Hearts were assayed for myocardial coenzyme Q10 and myocardial creatine kinase activity at end equilibration and at reperfusion. Treated hearts showed higher myocardial coenzyme Q10 levels (133 +/- 5 micrograms/gm ventricle versus 117 +/- 4 micrograms/gm ventricle, p < 0.05). Developed pressure at end reperfusion was 62% +/- 2% of equilibration in treatment group versus 37% +/- 2% in control group, p < 0.005. Preischemic myocardial aerobic efficiency was preserved during reperfusion in treatment group (0.84 +/- 0.08 mm Hg/(microliter O2/min/gm ventricle) vs 1.00 +/- 0.08 mm Hg/(microliter O2/min/gm ventricle) at equilibration, p = not significant), whereas in the control group it fell to 0.62 +/- 0.07 mm Hg/(microliter O2/min/gm ventricle, p < 0.05 vs equilibration and vs the treatment group at reperfusion. Treated hearts showed higher adenosine triphosphate and phosphocreatine levels during both equilibration (adenosine triphosphate 49% +/- 2% for the treatment group vs 33% +/- 3% in the control group, p < 0.005; phosphocreatine 49% +/- 3% in the treatment group vs 35% +/- 3% in the control group, p < 0.005) and reperfusion (adenosine triphosphate 18% +/- 3% in the treatment group vs 11% +/- 2% in the control group, CTRL p < 0.05; phosphocreatine 45% +/- 2% in the treatment group vs 23% +/- 3% in the control group, p < 0.005). Creatine kinase activity in treated hearts at end reperfusion was 74% +/- 3% of equilibration activity vs 65% +/- 2% in the control group, p < 0.05). Coenzyme Q10 pretreatment improves myocardial function after ischemia and reperfusion. This results from a tripartite effect: (1) higher concentration of adenosine triphosphate and phosphocreatine, initially and during reperfusion, (2) improved myocardial aerobic efficiency during reperfusion, and (3) protection of creatine kinase from oxidative inactivation during reperfusion.

Nitric oxide as a positive inotropic agent in isolated rat hearts

The purpose of this study was to examine the inotropic effects of nitroprusside (NP), a direct nitric oxide (NO) donor, in isolated rat hearts. Langendorff-perfused hearts (n = 5), paced at 6 Hz, were subjected to 15 min of equilibration (EQ) followed by infusion of NP, producing a coronary artery concentration of 1 x 10(-5) M. Coronary flow, left ventricular developed pressure (DP), end-diastolic pressure, and contractility and compliance (+/- dP/dt) were monitored throughout the experiment by a computerized data acquisition system. Myocardial oxygen consumption (MVO2) was measured at the end of EQ and after 2 1/2 min of NP infusion. Myocardial efficiency was calculated as the quotient of DP divided by MVO2. Values are expressed as the mean +/- SEM. Paired t tests were used to calculate statistical significance. Values for parameters monitored at end EQ and at 2 1/2 min NP infusion showed that there was a 93% increase in coronary flow, 18, 17, and 16% increases in developed pressure, contractility, and compliance, respectively, no significant change in end-diastolic pressure, a 49% increase in myocardial oxygen consumption, and a 21% decline in myocardial efficiency (P < 0.05 for all differences). We conclude that in the isolated rat heart, NO behaves as a positive inotrope.

The cumulative nature of pyruvate's dual mechanism for myocardial protection

Pyruvate (PYR) supplementation protects myocardium from ischemia reperfusion injury. This study was designed to characterize and quantify the mechanism underlying this protection: specifically whether this ability resides in PYR's metabolic effect or in its antioxidant effect. Isolated perfused rat hearts (n = 6/group) were subjected to 15 min of equilibration (EQ), 25 min of ischemia, and 10 min of reperfusion (RP). Glucose was the sole metabolic substrate (Control) or was supplemented with PYR (5 mM) during (a) EQ only (PYREQ group), (b) RP only (PYRRP group), or (c) EQ and RP (PYREQ-RP group). Left ventricular developed pressure (DP) and +/- dP/dt were recorded throughout the experiment. ATP concentrations and intracellular pH were determined by 31P NMR spectroscopy. Myocardial creatinine kinase (CK) activity was assayed at end EQ and end RP. In vitro, purified CK was assayed and, after exposure to H2O2 (200 microM) and increasing concentrations of PYR (0-6 mM) for 10 min, reassayed to determine the antioxidant effect of PYR. In all cases PYR improved recovery of mechanical function at end RP (DP: Control, 11 +/- 1%; PRYRP, 23 +/- 6%; PYREQ, 34 +/- 8%; PRYEQ&RP, 53 +/- 7%; P < 0.05 between all groups and Control). Ischemic contracture was delayed in hearts that received PYR during EQ (PYREQ and PYREQ&RP: 17.8 +/- 0.2 vs 12.5 +/- 0.3 min, P < 0.001). PYR during EQ (PYREQ and PYREQ&RP) led to higher end ischemic ATP levels (32 +/- 4% vs 14 +/- 3%, P < 0.001) and a more acidic end ischemic pH (5.92 +/- 0.02 vs 5.98 +/- 0.03 in Control and PYRRP, P < 0.05). PYREQ&RP showed the highest end reperfusion ATP levels (55 +/- 7% vs 38 +/- 4%, P < 0.05 vs other groups).(ABSTRACT TRUNCATED AT 250 WORDS)