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L Wiley Nifong

Publications and source records attributed to L Wiley Nifong.

At least 19 recordsLinked to original sources
PubMed2005

Robot-assisted epicardial ablation of the pulmonary veins: is a completed isolation necessary?

AIMS: To study the feasibility and electrophysiological efficacy of minimally invasive beating heart ablation of the pulmonary veins (PVs) via a robot-assisted single-sided approach. BACKGROUND: PV isolation by minimally invasive epicardial ablation may offer a new treatment for patients with lone atrial fibrillation (AF). However, complete PV isolation has been shown to be difficult to obtain. METHODS AND RESULTS: In 14 mongrel dogs, robot-assisted epicardial microwave ablation was performed on the beating heart by a single-sided right chest approach. Isolation of all PVs was performed in two steps to study the effect of an incomplete and a complete isolation on AF. AF was studied by random and burst pacing. Incremental pacing was performed to study conduction characteristics across the lesions. Opening of the pericardial reflections, introduction of the catheter and ablation were robotically feasible by a single-sided approach in 11 dogs. The AF duration decreased from 6.6+/-4.1 to 1.3+/-0.8 s (P=0.03) and 1.6+/-1.6 s (P=0.04 compared with control) after incomplete and completed isolation of the PVs. The AF cycle length increased from 134+/-5 to 141+/-5 and 145+/-8 ms (P=0.03) after incomplete and complete isolation, respectively. Several incomplete lesions showed 2:1 exit and/or entrance block during incremental pacing. After complete isolation, AF was no longer inducible from the PVs. CONCLUSION: Epicardial PV isolation can be successfully performed by a single-sided robot-assisted approach. The effect of PV ablation on AF is not an all or none phenomenon. Incomplete isolation already decreases AF duration and lengthens the AF cycle length. However, complete isolation is necessary to prevent AF induction by triggering from the isolated area.

Animals↗
PubMed2005

Robotic mitral valve annuloplasty with double-arm nitinol U-clips.

PURPOSE: Robotic mitral valve repair increases precision however operative times are longer. Prior studies have indicated that robotic knot tying is time consuming and it is without potential room for improvement. We therefore investigated tissue approximation devices that may shorten operative times. DESCRIPTION: A 67-year-old female was approached through a right mini-thoracotomy with the da Vinci Robotic Surgical System (Intuitive Surgical, Sunnyvale, CA). Using 12 nitinol U-clips (Coalescent Surgical, Sunnyvale, CA) an annuloplasty band was placed under robotic guidance. Clip placement and deployment times were recorded and statistical comparisons were assessed to prior suture annuloplasties. EVALUATION: Clip placement time was 1.3 +/- 0.9 (minutes +/- standard deviation), statistical comparison with first, most recent, and all prior suture annuloplasties proving no significance. Clip deployment time was 0.5 +/- 0.2, whereas knot-tying times and respective statistical comparison for first, most recent, and all prior suture annuloplasties were 2.0 +/- 0.7 (p = 0.003), 1.2 +/- 0.4 (p = 0.0004), and 1.6 +/- 0.6 (p < 0.00001). Follow-up echocardiography performed postoperatively, at 3 months, and at 9 months revealed valvular structural integrity with only minimal mitral regurgitation. CONCLUSIONS: U-clips considerably reduce time for annuloplasty over conventional suture and may help reduce operative times as well.

Aged↗
PubMed2005

Combining robotic mitral valve repair and microwave atrial fibrillation ablation: techniques and initial results.

BACKGROUND: Left atrial microwave ablation for atrial fibrillation has become popular for isolating autonomous atrial foci. Previously, mitral valve repairs (MVP) with atrial fibrillation ablation have been performed through sternotomy. We present a technique that combines robotic MVP with left atrial fibrillation ablation. METHODS: Through a 4-cm right minithoracotomy and using cardiopulmonary bypass, the transverse and oblique sinuses are accessed. A Flex-10 microwave catheter is passed around the pulmonary veins, and after weaning from cardiopulmonary bypass, peripulmonary vein microwave ablations are performed. After cardioplegic arrest, the da Vinci system is used to manipulate the catheter to create endocardial lesions around the left atrial appendage. Another endocardial lesion is made connecting the pulmonary venous line with the mitral annulus near P3. The left atrial appendage is closed, and the MVP performed robotically. Data are expressed as mean +/- standard deviation. RESULTS: Sixteen patients underwent this combined procedure, with 80% returning to a normal sinus rhythm at 6 weeks and 73% remaining in normal sinus rhythm at 6 months. Only 1 patient was in atrial fibrillation at 6 months. The ablation procedure added 42 +/- 16.1 minutes to a robotic MVP. The average length of hospital stay was 6.3 +/- 2.2 days, 1.3 days longer than the mean of the prior 50 consecutive robotic MVP patients without a concomitant ablation. CONCLUSIONS: Robotic microwave ablation during robotic MVP is a safe, effective way to resolve atrial fibrillation. These methods offer a promising prelude to the combined totally endoscopic treatment of atrial arrhythmias and mitral insufficiency.

Aged↗
PubMed2005

Robotic mitral valve surgery: a United States multicenter trial.

OBJECTIVE: In a prospective phase II Food and Drug Administration trial, robotic mitral valve repairs were performed in 112 patients at 10 centers by using the da Vinci surgical system. The safety of performing valve repairs with computerized telemanipulation was studied. METHODS: After institutional review board approval, informed consent was obtained. Patients had moderate to severe mitral regurgitation. Operative technique included peripheral cardiopulmonary bypass, a 4- to 5-cm right minithoracotomy, a transthoracic aortic crossclamp, and antegrade cardioplegia. The successful study end point was grade 0 or 1 mitral regurgitation by transthoracic echocardiography at 1 month after surgery. RESULTS: Valve repairs included quadrangular resections, sliding plasties, edge-to-edge approximations, and both chordal transfers and replacements. The average age was 56.4 +/- 0.09 years (mean +/- SEM). There were 77 (68.8%) men and 35 (31.2%) women. Valve pathology was myxomatous degeneration in 105 (91.1%), and 103 (92.0%) had type II leaflet prolapse. Leaflet repair times averaged 36.7 +/- 0.2 minutes, with annuloplasty times of 39.6 +/- 0.1 minutes. Total robot, aortic crossclamp, and cardiopulmonary bypass times were 77.9 +/- 0.3 minutes, 2.1 +/- 0.1 hours, and 2.8 +/- 0.1 hours, respectively. On 1-month transthoracic echocardiography, 9 (8.0%) had grade 2 mitral regurgitation, and 6 (5.4%) of these had reoperations (5 replacements and 1 repair). There were no deaths, strokes, or device-related complications. CONCLUSIONS: Multiple surgical teams performed robotic mitral valve repairs safely early in development of this procedure, with a reoperation rate of 5.4%. Advancements in robotic design and adjunctive technologies may help in the evolution of this minimally invasive technique by decreasing operative times.

Adult↗
PubMed2005

Acute effects of suction retraction on atrial hemodynamics and histology.

OBJECTIVES: In minimally invasive and robotic mitral valve surgery, a blade retractor is used to elevate the left atrial roof, which often distorts tissue and impairs visualization. We tested the hemodynamic and histologic changes of intra-atrial suction, using a new suction retractor that may improve stabilization and visualization. METHODS: Swine were divided into 3 equal (n = 4) groups: blade retractor, suction retractor, and arrested heart control. Left atrial ultrasonic crystals were used to record ejection fractions. After cardioplegic arrest, the atrium was opened and sampled for preretractor histology. Retractors remained in place for 1 hour, followed by postretractor histologic sampling. Controls were crossclamped for an equivalent time and postarrest histologic data obtained. Animals were weaned from bypass, data were collected for 4 hours, and postsacrifice atrial histologic samples were obtained. RESULTS: The main effect due to treatment was not statistically significant ( P = .52) between the 3 groups, with the 4-hour average ejection fraction for blade retractor, suction retractor, and control being statistically equivalent at 33.3% +/- 8.3, 35.3% +/- 12.1, and 40.8% +/- 9.9 (mean +/- standard deviation), respectively. Histology showed equivalent amounts of myocyte fragmentation, interstitial edema, eosinophilia, and wavy fibers between blade retraction and suction retraction, while the latter showed slightly increased amounts of hemorrhage. CONCLUSIONS: Atrial endocardial suction retraction appears to be safe with no acute changes in the left atrial ejection fraction or significant acute histologic differences, compared to blade retraction. Furthermore, intra-atrial suction may be applicable to procedures other than minimally invasive and robotic mitral valve repair for providing improved stabilization.

Animals↗
PubMed2005

Reexamining contraindications for minimally invasive mitral valve surgery.

Historically, contraindications to minimally invasive or robotic mitral valve surgery have included prior mastectomy, thoracic reconstruction, or chest radiation. However, we believe that by granting flexibility in the choice of skin incision site while performing careful dissection, surgeons can provide these patients the outstanding results afforded by a minithoracotomy. We present a patient who had undergone a prior mastectomy and radiation treatment in whom we performed a minimally invasive mitral valve repair through a right-sided minithoracotomy using the previous mastectomy incision.

Cardiac Surgical Procedures↗
PubMed2004

Building a surgical robotics program.

Building a strong institutional robotics program requires commitment from administrative and clinical departments. Here we present issues to be considered when developing such a program, including development of a pathway for introduction of the technology into patient care, team recruitment, creation of an objective-based curriculum, multispecialty training, and proper patient selection.

Curriculum↗
PubMed2004

Robotic skeletonizing of the internal thoracic artery: is it safe?

BACKGROUND: The advantages of internal thoracic artery skeletonization include early high blood flow, a longer conduit, and less bleeding than pedicle internal thoracic artery grafts. Longer conduits are needed for complete endoscopic arterial revascularization. Therefore this study was designed to determine the feasibility and safety of internal thoracic artery skeletonization using the da Vinci robotic system (Intuitive Surgical, Sunnyvale, CA). METHODS: Nine dogs underwent bilateral robotic internal thoracic artery harvesting through three ports placed in the left chest. One internal thoracic artery was harvested as a pedicle in each dog, and the other was skeletonized. Internal thoracic artery blood flow was measured in each graft, and comparative endothelial histologic studies were performed. Data are mean +/- the standard error of the mean. RESULTS: All 18 internal thoracic arteries were harvested successfully. Skeletonized internal thoracic artery harvests required more time (48.0 minutes +/- 1.8) than pedicle internal thoracic artery harvests (39.0 minutes +/- 1.4; p < 0.05). Internal thoracic artery flows during the final intervals were similar (skeletonized = 30.0 mL/min +/- 2.4 vs pedicle = 31.5 mL/min +/- 1.8; p = 0.9). Free internal thoracic artery bleeding flow was similar in both groups (skeletonized = 162.0 mL/min +/- 3.0 vs pedicle = 189.0 mL/min +/- 2.4; p = 0.4). Histologically, both groups were similar with minimal endothelial damage. CONCLUSIONS: Robotically skeletonized harvesting is safe, but it requires more time (48.0 minutes +/- 1.8) than pedicle internal thoracic artery harvesting. Despite muted tactile feedback with robotics, neither technique was associated with histologic or functional damage. These encouraging results may represent an advantage for complete arterial revascularization in robotic coronary bypass patients.

Animals↗
PubMed2004

Robotically-assisted left atrial fibrillation ablation and mitral valve repair through a right mini-thoracotomy.

A combined robotic-assisted left atrial ablation and mitral valve repair was done through a 5-cm right anterior mini-thoracotomy. The patient was a 54-year-old man with severe mitral regurgitation and a 10-month history of persistent atrial fibrillation. The patient underwent off-pump, beating heart epicardial peripulmonary vein microwave ablation using the FLEX 10 catheter (AFx Inc, Fremont, CA), followed by supplemental on-pump endocardial lesions. The procedure was done using the da Vinci surgical robot (Intuitive Surgical Inc, Sunnyvale, CA). The mitral valve repair consisted of a No. 38 Cosgrove annuloplasty band implantation (Edwards Life Sciences, LLC, Irvine, CA). The postoperative recovery was uneventful, and the patient maintained normal sinus rhythm.

Atrial Fibrillation↗
PubMed2004

Evaluation of epicardial microwave ablation lesions: histology versus electrophysiology.

BACKGROUND: Pulmonary vein isolation is a hallmark in current surgical ablation for atrial fibrillation. However, validation of isolation remains cumbersome. We evaluated electrophysiologic and not histologic means to test isolation. METHODS: In 16 mongrel dogs, robot-assisted epicardial beating-heart microwave ablation (FLEX 10) was performed around the pulmonary veins. Electrophysiologic isolation was tested by pacing at 4 times threshold values inside and outside the pulmonary veins (exit and entrance block). The histology of lesions was studied for transmurality and continuity of the lesion lines. In 5 dogs, lesions were studied at various time intervals. RESULTS: Histologic evaluation of the lesions showed incomplete (48% +/- 20%) circumferential myocardial damage in all dogs with acute lesions. Electrophysiologic evaluation showed completion of the box (entrance and exit block) in 8 dogs and in another 5 dogs after repeated ablation (p < 0.01 compared with histologic evaluation). Electrophysiologic evaluation of the dogs with chronic lesions showed completed lesions in 4 of 5 dogs directly after ablation. At follow-up (1 to 3 weeks), the isolations remained electrophysiologically complete. Histologic evaluation of the lesions 1 to 3 weeks after ablation showed complete (100%) circumferential lesions in all 4 dogs (p < 0.001 compared with the histology of dogs with acute lesions). CONCLUSIONS: Directly after treatment, ablation lesions are best evaluated electrophysiologically, because complete (transmural and circumferential) lesions are not shown by histologic evaluation in the acute stage. After 1 to 3 weeks, the histology is in accordance with the electrophysiology. To obtain a complete isolation, online electrophysiologic evaluation during pulmonary vein microwave ablation is necessary to optimize the results.

Animals↗
PubMed2004

Robotics in valvular surgery: 2003 and beyond.

PURPOSE OF REVIEW: Currently, cardiac surgery is an evolving field. Not only has there been a technologic explosion, but there is also a strong interest in minimally invasive operations. Mitral valve surgery can now be performed with the use of sophisticated robotic systems through small incisions, and a review of recent advances is warranted. RECENT FINDINGS: Various groups have now documented that robotic valve surgery is feasible and safe. Despite an initial learning curve, facility with the procedure is gained with increasing experience. SUMMARY: Robotic mitral valve surgery is a procedure that is gaining widespread popularity. The patient of today and the future will demand minimally invasive operations. Initial clinical experience with robotic systems will allow further developments. Ultimately, this may result in completely endoscopic heart surgery.

Heart Valve Diseases↗
PubMed2004

Methylene blue enhancement of resuscitation after refractory hemorrhagic shock.

BACKGROUND: Methylene blue has been used to treat hypovolemic states. This study evaluated prehospital resuscitation after refractory hemorrhagic shock with a combination of methylene blue and limited-volume lactated Ringer's solution. METHODS: After blood loss to a mean arterial pressure of 50 mm Hg in canines, refractory hemorrhagic shock was defined as minimal hemodynamic response to phenylephrine. Differential protocols included no treatment (control), methylene blue bolus, limited-volume lactated Ringer's solution, and combined methylene blue/lactated Ringer's solution therapies. Hemodynamic parameters were collected at baseline, during shock, during refractory hemorrhagic shock, and 30, 60, 90, and 120 minutes after treatment. Radiolabeled microspheres were used to measure end-organ perfusion and oxygen delivery. RESULTS: Methylene blue/lactated Ringer's resuscitation improved prehospital survival (p < 0.05), mean arterial pressure and cardiac output (p < 0.05), vital end-organ blood flow and oxygen delivery (p < 0.05), and decreased serum lactate levels (p < 0.05), as compared with the methylene blue and lactated Ringer's single therapies. CONCLUSIONS: Resuscitation after refractory hemorrhagic shock using a combination of methylene blue and limited-volume lactated Ringer's solution improves prehospital survival and hemodynamic stability and reduces ischemic damage in an acute setting. This form of therapy has been proved useful as a temporizing measure for resuscitation after refractory hemorrhagic shock in a canine model and warrants further study for its application to the hemorrhagic trauma patient.

Animals↗
PubMed2004

Should a video-assisted mini-thoracotomy be the approach of choice for reoperative mitral valve surgery?

BACKGROUND AND AIM OF THE STUDY: Reoperative cardiac surgery carries a greater morbidity and mortality than primary cardiac surgery. The study aim was to compare perioperative outcomes in patients undergoing mitral valve surgery who had already undergone a previous cardiac operation using either a minimally invasive video-assisted (MIVA) mini-thoracotomy or a redo median sternotomy (MS). METHODS: Between January 1996 and June 2003, 71 consecutive patients with prior cardiac surgery underwent mitral valve surgery. Of these operations, 38 were MIVA procedures, performed through a 5-cm right anterior thoracotomy using voice-activated robotic camera control (AESOP 3000). Outcome was compared with results in 33 consecutive patients who underwent a standard redo MS. RESULTS: The MIVA and redo MS cohorts differed in preoperative ejection fraction (46 +/- 2% versus 55 +/- 2%; p = 0.004) and percentage of urgent operations (33 versus 8.3%; p = 0.01). Operative mortality was similar in both groups (5.7% and 5.9% respectively; p = 0.976), as were cardiopulmonary bypass, operating room, and ICU times. Postoperative intubation time was shorter in the MIVA group than in the redo MS group (29.1 +/- 8.9 versus 38.0 +/- 9.9 h; p = 0.008), and blood transfusion requirements were also reduced (2.9 +/- 0.6 versus 5.5 +/- 0.7 units; p = 0.001) respectively. Length of hospital stay was significantly less in the MIVA group (7.1 +/- 1.3 versus 11.2 +/- 1.1 days; p = 0.001). CONCLUSION: Minimally invasive video-assisted mitral valve operations may be performed safely and efficiently in patients with prior cardiac surgery. Demonstrated advantages include fewer red blood cell and blood product transfusions, as well as decreased intubation time and length of hospital stay.

Aged↗
PubMed2004

Robot-assisted sutureless minimally invasive mitral valve repair.

Our institution has performed over 100 robot-assisted mitral valve repairs. The procedure has shown many advantages to conventional sternotomy-based repair. However, the robotic approach leads to longer cross-clamp and bypass times than conventional sternotomy. As a result of the increased risk of myocardial damage and arrhythmias from lengthy arrest times, nitinol U-clips have been used in the laboratory and currently in patients for the tissue-annuloplasty ring approximation. The technology replaces the time-consuming task of knot tying, as well as provides better visualization during placement of the annuloplasty ring. The animal studies show excellent tissue incorporation. Short-term echocardiographic imaging shows durability without evidence of mitral stenosis or regurgitation. Further studies are ongoing in our patient population, and the data suggest shorter, more efficient and effective robot-assisted mitral valve repairs.

Cardiac Surgical Procedures↗
PubMed2003

Angiogenic growth factor response to acute systemic exercise in human skeletal muscle.

We investigated whether acute systemic exercise increases vascular endothelial growth factor (VEGF), VEGF receptor (KDR and Flt-1) mRNA, and VEGF protein in sedentary humans. Twelve sedentary subjects were recruited and performed 1 h of acute, cycle ergometer exercise at 50% of maximal oxygen consumption. Muscle biopsies were obtained from the vastus lateralis before exercise and at 0, 2, and 4 h postexercise. Acute exercise significantly increased VEGF mRNA at 2 and 4 h and increased KDR and Flt-1 mRNA at 4 h postexercise. The sustained increase in VEGF mRNA through 4 h and the increases in KDR and Flt-1 at 4 h are different from their respective time course responses in rats. In contrast to the increase in VEGF mRNA postexercise, VEGF protein levels were decreased at 0 h postexercise. These results provide evidence in humans that 1) VEGF, KDR, and Flt-1 mRNA are increased by acute systemic exercise; 2) the time course of the VEGF, KDR, and Flt-1 mRNA responses are different from those previously reported in rats (Gavin TP and Wagner PD. Acta Physiol Scand 175: 201-209, 2002); and 3) VEGF protein is decreased immediately after exercise.

Adult↗
PubMed2003

Robotic mitral valve repair: experience with the da Vinci system.

BACKGROUND: As part of a Food and Drug Administration trial, mitral repairs were performed in 38 patients using the robotic da Vinci surgical system (Intuitive Surgical, Inc, Mountain View, CA). Prospectively, we evaluated safety and efficacy in performing both simple and complex mitral repairs. METHODS: Eligible patients had nonischemic moderate to severe mitral insufficiency. Operative techniques included peripheral cardiopulmonary perfusion, a 4- to 5-cm mini-thoracotomy, transthoracic aortic occlusion, and antegrade blood cardioplegia. Transesophageal echocardiograms were done intraoperatively with three-dimensional reconstructions. Successful repairs were defined as mild or less residual regurgitation. RESULTS: Enhanced three-dimensional visualization of mitral leaflets and the subvalvar apparatus allowed safe, dexterous intracardiac tissue manipulation. All patients had successful valve repairs including quadrangular resections, sliding plasties, and edge-to-edge approximations, as well as both chordal transfers and replacements. There were no operative deaths, strokes, or device-related complications. One patient required valve replacement for hemolysis and 1 was reexplored for bleeding. There were no incisional conversions. Both robotic repair and total operating times decreased significantly from 1.9 +/- 0.1 and 5.1 +/- 0.1 hours (mean +/- standard error of the mean) for the first 19 patients to 1.5 +/- 0.1 (p = 0.002) and 4.4 +/- 0.1 hours (p = 0.04) for the last 19 operations, respectively. Total hospital length of stay for patients was 3.8 +/- 0.6 days. Of all patients, 31 (82%) had a 4-day or less length of stay. Seven patients (18%) had stays between 5 and 9 days (6.4 +/- 1.0). CONCLUSIONS: This study shows that the da Vinci surgical system (Intuitive Surgical, Inc) has few limitations in performing complex valve repairs. Articulated wrist-like instruments and three-dimensional visualization enabled precise tissue telemanipulation. Future robotic design advances and adjunctive suture technologies may promote continuing evolution of robotic cardiac operations.

Cardiac Surgical Procedures↗
PubMed2003

Outcomes and perioperative hyperglycemia in patients with or without diabetes mellitus undergoing coronary artery bypass grafting.

BACKGROUND: The association between perioperative hyperglycemia and outcomes in patients with and without diabetes mellitus undergoing coronary artery bypass grafting is not well defined. We measured the association between perioperative hyperglycemia and outcomes among patients undergoing coronary artery bypass grafting. METHODS: We report a historic cohort study of 1574 patients who had undergone coronary artery bypass grafting between 1998 and 1999, 545 (34.6%) with diabetes. Perioperative blood glucose level was defined as the average of all blood glucose tests obtained on the day of and the day after surgery. Outcomes were 30-day mortality, infection rates (sternum, harvest site, sepsis, pneumonia, urinary tract), and resource utilization. RESULTS: After adjusting for diabetes status and calculated preoperative mortality or mediastinitis risk scores, each 50 mg/dL (2.78 mmol/L) blood glucose increase was not statistically associated with higher mortality (odds ratio 1.37; 95% confidence interval, 0.98 to 1.92; p = 0.07), or higher infection rate (odds ratio 1.23, 95% confidence interval 0.94 to 1.60; p = 0.14). Each 50 mg/dL blood glucose increase was associated with longer postoperative days by 0.76 days (95% confidence interval 0.36 to 1.17 days; p < 0.001), increased hospitalization charges by 2824 dollars (95% confidence interval 1599 dollars to 4049 dollars; p < 0.001), and increased hospitalization cost by 1769 dollars (95% confidence interval 928 dollars to 2610 dollars; p < 0.001). In the unadjusted analysis, infections occurred more frequently in patients with diabetes (6.6% vs 4.1%, p = 0.03). CONCLUSIONS: Perioperative hyperglycemia is associated with increased resource utilization in patients undergoing coronary artery bypass grafting with and without diabetes.

Blood Glucose↗