Minimally invasive cardiac surgery

In a short period of time, tremendous progress has been made in the field of minimally invasive cardiac surgery. The goal of true "minimally invasive" cardiac surgery should be a totally thoracoscopic or transvascular procedure that allows a very short hospital stay and prompt patient recovery at acceptable costs. To accomplish this goal, efforts to miniaturize and refine instrumentation/cannulae/visualization and the development of innovative new techniques must be pursued. The concept of performing intracardiac repair of a variety of pathologies on the beating heart is under investigation and will require a new generation of technology, which will include through-blood imaging, such as blood displacement videoscopes, and task-specific instruments. Robotics may offer additional assistance in the performance of complex and fine maneuvers.     

Minimally invasive knee joint surgery

The treatment of knee joint injuries has seen a marked development. Arthroscopy is standard for diagnostic purposes, for meniscus resection and meniscus refixation. Anterior cruciate ligament reconstruction may be performed mini-invasive by arthroscopic or mini-open technique with comparable result. Drill guide systems and fixation techniques allow for precise and stable graft placement. Posterior cruciate ligament surgery is presently undergoing a similar process of optimisation as ACL surgery has some years ago. The surgical trauma of intraarticular fracture reconstruction was also reduced significantly. Retrograde nailing, percutaneous plating and specific exposures to distal femur and proximal tibia fractures have been established. Percutaneous osteosynthesis controlled by arthroscopy or fluoroscopy is widely used for B-fractures of the tibial plateau. Injectable bone mineral cement adds to reduced trauma of surgical treatment of these fractures. Mini-invasive knee surgery will develop rapidly in the coming years.     

Minimally invasive pediatric cardiac surgery

We quantitatively studied the role of periosteum and bone marrow-endosteum during lengthening in 18 growing rabbits, comparing four surgical procedures: 1) periosteum and bone marrow preservation, 2) periosteum preservation, bone marrow destruction, 3) periosteum destruction, bone marrow preservation, 4) periosteum and bone marrow destruction. An external fixator was set on one femur, the other serving as a control. Distraction began on day 5 and stopped on day 25 (0.25 mm/12 hours). On day 30, femora were harvested with a layer of muscle. Area, bone mineral content and density were measured by dual-energy x-ray absorptiometry. Procedure 2 showed the highest increase in bone mineral content around the elongated callus (127%) compared to procedures: 1 (81%), 3 (25%) and 4 (-8%, i.e., resorption of bone ends). A statistically significant effect on bone formation was observed when preserving (vs. destroying): 1) periosteum, 2) bone marrow (effect observed only around the distraction gap), 3) periosteum and bone marrow in combination. Periosteum alone forms a larger callus, with more mineral content than bone marrow alone, and destruction of both results in the absence of bone formation around the distraction area. Careful preservation of periosteum is essential to bone healing. Formation of bone with a large mineral content does not require bone marrow preservation, but there is an interaction effect on healing between bone marrow and periosteum.     

Minimally invasive interventions in heart surgery

Recently a number of minimally invasive surgical techniques have been developed in order to reduce surgical trauma especially to avoid median sternotomy and cardio-pulmonary bypass (CPB). In March 1996 we started successfully a clinical trial with the Port Access technique at our institution for the first time in Europe for the treatment of coronary artery single vessel disease. In addition mitral valve disease, aortic valve disease and ASD were treated successfully with minimally invasive surgical techniques. We developed a new minimally invasive surgical technique (Dresden technique) for the treatment of coronary artery multi vessel disease at our institution. Besides we used several minimally invasive surgical techniques without CPB. Our results indicate that minimally invasive surgical techniques routinely used will decrease the morbidity and time of convalescence after cardiac surgery. These techniques can be applied for a variety of cardiac diseases.     

Minimally invasive surgery for solid tumors

The use of minimally invasive surgery in patients with cancer is slowly evolving. There are a number of reports describing laparoscopy in adults for pancreatic, ovarian, gastric, and colon cancers. In addition, thoracoscopy has been described for lung and esophageal cancers. The role of laparoscopy and thoracoscopy in children with cancer is less clear because a number of pediatric neoplasms are sensitive to adjuvant therapy and surgery is often part of a planned multi-dimensional approach. This article describes a previous reported experience with minimally invasive surgery in children with cancer, current indications for this approach, and general principles which are important regarding the operative technique. In addition, future applications for this technology are suggested.     

Minimally invasive direct coronary artery bypass surgery

Traditional coronary artery bypass surgery involves a median sternotomy and the use of a heart-lung machine to stabilize the heart during suturing. Minimally invasive coronary artery surgery employs small incisions directly over the target vessels and avoids the use of a heart-lung machine, which can cause postoperative complications. The target coronary vessels are stabilized in alternative ways, potentially hazardous manipulation of the ascending aorta is avoided, and the subclavian and axillary arteries provide alternative inflow sources. Other new techniques used in minimally invasive procedures include a coronary artery cannula to avoid intraoperative ischemia and wound irrigation catheters to administer postoperative bupivacaine hydrochloride. Perioperative nurses need to become familiar with these new techniques to be able to plan and implement effective patient care.     

Minimally invasive valve surgery versus the conventional approach

As a result of reports touting the effectiveness of minimally invasive valve operations, many cardiovascular surgeons and their patients are beginning to believe that smaller incisions are always better. According to its proponents, the minimally invasive approach results in less pain, a faster recovery, and a more satisfactory cosmetic result. Proponents also believe that the operation can be done safely and effectively at a lower cost than traditional surgical approaches. This may not be the case, however, and additional prospective studies must be done before firm conclusions can be drawn. For example, cardiopulmonary bypass, myocardial ischemia, and overall operative times are significantly longer (40% or more) for minimally invasive surgical procedures. Morbidity and mortality rates do not appear to be decreased, the length of hospital stay varies by only 1 or 2 days, and patients do not necessarily report less postoperative pain. When the conventional technique is used, the operation can be performed precisely and expeditiously. Should complications occur, the surgeon will have direct access to the heart. The cost of a conventional procedure should not be much more than that of a minimally invasive procedure, and in some instances it may even be less-particularly when the less invasive procedure significantly extends the operating room time or requires additional monitors or costly disposables.     

Minimally invasive disc surgery. Nucleotomy versus fragmentectomy

There is continued debate as to the optimum surgical management of a herniated disc with sciatica. There are proponents of conventional microdiscectomy as well as those who advocate minimally invasive approaches, including central disc decompression or nucleotomy as well as arthroscopic lumbar microdiscectomy and fragmentectomy. In this controversy (I), Dr. Gary Onik takes the position that central disc decompression is both safe and efficacious and may be the procedure of choice for recurrent disc herniations (II). Dr. Parvis Kambin takes the opposing position and advocates arthroscopically assisted fragmentectomy as the procedure of choice.     

Minimally invasive cardiac surgery: current status and perspective

This study investigated the features of calf deep vein thrombosis (DVT) as a pulmonary embolic source. Fifty-eight lower limbs in 29 patients who were suspected of having DVT distal to the popliteal vein were screened by ultrasonography. Then, ascending venography was performed to confirm the diagnosis. Pulmonary embolism (PE) was diagnosed in suspected patients by use of pulmonary perfusion scanning or pulmonary angiography. Venography revealed calf DVT in 33 limbs in 28 patients. Of 28 patients, six had symptomatic PE. Thrombosis was found in the muscle veins in 18 limbs, the trunk veins in 11, and both veins in four. Isolated single vein thrombosis was found in the soleal vein in 14 limbs (42%), the posterior tibial vein in eight, the peroneal vein in two, and the gastrocnemius vein in two. The overall percentage of soleal vein thrombi was 61%. All six patients with symptomatic PE had isolated soleal vein thromboses. Calf DVT was a pulmonary embolic source when isolated thrombosis of the large soleal vein was more than 7 mm in diameter. Soleal veins were the most frequent and important location of calf DVT, suggesting that these were an occasional embolic source of critical PE.     

Minimally invasive surgery in the management of Mirizzi syndrome]

BACKGROUND: Evidence accumulating over the last 10 years suggests that the exposed spinal cord tissue in a myelomeningocele sustains a secondary injury as the result of prolonged exposure to the intrauterine environment. These data suggest that early closure of the myelomeningocele sac might prevent such injury and in turn improve the neurologic outcome in the affected infant. METHODS: Three patients with fetuses carrying the ultrasonic diagnosis of myelomeningocele elected to enter a study of the feasibility of repairing myelomeningocele in utero. At approximately 28 weeks of gestation each patient underwent laparotomy and hysterotomy, thus exposing the myelomeningocele defect. The defect was closed in a routine surgical fashion, and the hysterotomy was then closed. RESULTS: The 3 patients recovered from surgery without incident. Early premature contractions subsided, and they were discharged by the 5th postoperative day. At between 33 and 36 weeks of gestation, each infant was delivered via cesarean section. The observed neurologic deficits were within the range expected from the anatomic level of the defects. Two of the infants have not required ventriculoperitoneal shunting. CONCLUSIONS: This limited series of patients suggests that myelomeningocele can be repaired in utero with minimal morbidity to either the mother or her fetus. A larger study will be needed to substantiate this low morbidity and to determine the extent of any neurologic benefit of early surgery.     

Minimally invasive surgery for coronary disease: a new alternative

To avoid the inflammatory syndrome generated by cardiopulmonary bypass, a new surgical technique, minimal invasive direct coronary artery bypass (MIDCAB), has been developed. An anastomosis is performed between the left internal mammary artery (LIMA) and the left anterior descending artery (LAD) on a beating heart, through a limited anterior thoracotomy. We describe our experience with this technique. Ten consecutive patients underwent a MIDCAB procedure. (9 males, age 65.9 +/- 9 years). There were 8 bypasses of the LIMA on the LAD, one bilateral mammary bypass on the LAD and the right coronary artery, and one conversion to a standard sternotomy with CPB for a saphenous vein bypass on the LAD because of injury to the LIMA (2nd case). There was one redo for haemostasis of the mammary artery bed (3rd case). The first 3 patients required postoperative blood transfusion. From the 4th operation onwards, with the introduction of new instrumentation which was better adapted to the narrowness of the surgical field, there were no further surgical complications. During the follow-up (mean 5 months; range 2-9), no patient suffered anginal recurrence. With the improvement of instrumentation, the MIDCAB technique offers satisfactory short- and mid-term results, while avoiding CPB with its adverse effects. Lastly, the cosmetic result is far better than with the conventional procedure.     

Minimally invasive surgery with the Port-Access method. Preliminary experience

METHODS: Data from the initial experience of 40 patients operated on with the Port-Access technique are reported. Indication to surgery was mitral disease in 24 patients and coronary stenosis in 16 patients. Mean age was 52 years (range 32-75). Operations performed were: 8 mitral valvuloplasties, 16 valve replacements, 9 single CABG (associated with an MVR in one case), 1 double CABG, 6 triple CABG and one quadruple CABG. Coronary endarterectomy was performed in 5 patients and left atrial isolation was associated with MV surgery in 5 cases. RESULTS: There were no operative deaths and every patient was discharged after a mean postoperative stay of 5.5 days (range 3-30). Postoperative course was complicated in 7 patients: surgical revision was necessary in 4 patients due to bleeding (through the mini-thoracotomy incision in 3 cases), 1 pacemaker was implanted for A-V block, one retained pulmonary catheter was removed through the mini-thoracotomy without the aid of cardiopulmonary bypass and in one case, there was an emergency conversion to median sternotomy due to a ventricular fibrillation unresponsive to usual resuscitative maneuvers a few hours after surgery. Some of these complications can be ascribed to the learning phase of this new technique and should disappear as experience is increased. CONCLUSIONS: Port-Access surgery is a new minimally invasive technique that utilizes a cardiopulmonary bypass with femoral access and a specialized catheter system that provides endoaortic clamping, pulmonary artery venting and myocardial preservation with infusion of cardioplegic solution in the aortic bulb or in the coronary sinus. Major contraindications to this technique are iliac-femoral disease or severe dilatation of ascending aorta. The aim of the Port-Access technique is to combine the aesthetic and functional advantages of the minimally invasive surgery with the wide range of surgical options that cardiopulmonary bypass can afford (to operate on atrioventricular valves and perform all the CABG that the patient need), without the limitations characteristic of the classic minimally invasive direct coronary artery bypass (MIDCAB) technique.     

Minimally invasive coronary surgery at the beginning of the new millennium

Several formulations of poly(epsilon-caprolactone) (PCL), poly(lactic acid) (PLA), and poly(lactic-co-glycolic acid) (PLGA) nanocapsules containing phenylbutazone were prepared according to the interfacial deposition technique. These formulations differed in the type of polymer used to form the shell of the nanocapsules. Analysis of particle size distribution and encapsulation efficiency of the nanocapsules revealed that the type and molecular weight of polyester used were the main factors influencing these properties. PLA had the highest encapsulation efficiency with the best reproducibility. From in vitro release studies, a small amount of drug release was observed at pH 7.4. However, in the gastric medium, an important burst effect occurred and was highest with the PLGAs and lowest with PCL, suggesting that drug release from these systems is affected by the type of polymer and the environmental conditions. The two formulations of phenylbutazone-loaded nanocapsules should be evaluated based on PCL and PLA in vivo in order to determine to what extent they are able to reduce the local side effects of this drug.