Blood supply of the sternum and its importance in internal thoracic artery harvesting

Pathological study of sternal osteomyelitis after median thoracotomy-a prospective cohort study

PURPOSE

Osteomyelitis of the sternum may arise either as a primary condition or secondary to median thoracotomy after cardiac surgery, with the latter being decidedly more frequent. Deep sternal wound infections appear as a complication of median thoracotomy in 0.2 to 4.4% of cases and may encompass the infection of the sternal bone. To date, there are no exhaustive histopathological studies of the sternal osteomyelitis.

METHODS

Our work group developed a surgical technique to remove the complete infected sternal bone in deep sternal wound infections. We therefore prospectively examined the en bloc resected sternal specimens. Seven standard histological sections were made from the two hemisternums.

RESULTS

Forty-seven sternums could be investigated. The median age of the patients in the cohort was 66 (45-81) years and there were 10 females and 37 males. Two methods were developed to examine the histological findings, with one model dividing the results in inflammatory and non-inflammatory, while the second method using a score from 0 to 5 to describe more precisely the intensity of the bone inflammation. The results showed the presence of inflammation in 76.6 to 93.6% of the specimens, depending on the section. The left manubrial sections were more prone to inflammation, especially when the left mammary artery was harvested. No further risk factors proved to have a statistical significance.

CONCLUSION

Our study proved that the deep sternal wound infection may cause a ubiquitous inflammation of the sternal bone. The harvest of the left mammary artery may worsen the extent and intensity of infection.

Refinement of Coronary Artery Bypass Grafting at Juntendo University Hospital

Surgical treatment of ischemic heart disease began in 1945. After 1970, coronary artery bypass grafting (CABG) with cardiopulmonary bypass was developed along with coronary angiography. Juntendo University has been treating ischemic heart disease since 1980, and is actively performing off-pump CABG (OPCAB) since 2002. Besides the age of patients undergoing surgery, complications such as chronic hemodialysis, cerebrovascular disease, and malignancies make it challenging to reduce postoperative complications using OPCAB as graft preservation. OPCAB is technically challenging, and the CORONARY trial did not reveal its superiority over conventional CABG. Furthermore, high revascularization rates and technical differences among surgeons are important concerns. While not widely accepted in Europe and the United States, OPCAB comprises 65% of all stand-alone CABG in Japan. Japan reported a 2.5% hospital mortality rate in 2018, while the US reported 2.2% (according to the American Association of Thoracic Surgeons). In contrast, Juntendo University Hospital has maintained a 1% hospital mortality rate since 1984. To reduce the incidence of remote stroke in CABG patients, Juntendo has been using stroke-free management since 2010. Postoperative atrial fibrillation is 4-5 times more likely to recur than normal sinus rhythm after a 5-year course. In our study, 20% of patients suffered from chronic atrial fibrillation after ten years. Furthermore, left atrial appendage closure or amputation significantly reduces stroke in patients who undergo CABG and develop postoperative atrial fibrillation. Thus, OPCAB is a minimally invasive procedure with fewer complications; prevention of cardiogenic cerebral infarction can help improve remote outcomes.

Up-to-Date, Skeletonized or Pedicle Bilateral Internal Mammary Artery; Does It Matter?

PURPOSE

In this article, we reported on the up-to-date literature regarding skeletonized bilateral internal mammary artery (BIMA) flow and the effect on sternal perfusion. We also reviewed the pros and cons of the skeletonization technique versus the conventional pedicle technique for harvesting the BIMA.

METHODS

We performed an up-to-date review using the PubMed database, with a specific focus on the contemporary published literature.

RESULTS

BIMA skeletonization can preserve the sternal microcirculation, minimize tissue damage, and maintain blood supply to the chest wall at the tissue level. This effect is also apparent in diabetics. Deep sternal wound infection (DSWI) rates are significantly less with skeletonization versus the conventional pedicle technique and are comparable to single internal mammary artery harvesting.

CONCLUSIONS

Contemporary large-scale studies demonstrate that skeletonization of the BIMA increases conduit length, provides superior flow, reduces the incidence of DSWIs, and improves late survival. Hopefully, this review will increase awareness of the compelling evidence in favor of using skeletonized internal mammary arteries and stimulate increased uptake of BIMA revascularization surgery.

Impact of skeletonized harvesting of the internal thoracic artery on intrasternal microcirculation considering preparation quality

OBJECTIVES

Previous studies have demonstrated the impact of internal thoracic artery (ITA) harvesting on microcirculation in parasternal tissues. However, the impact of skeletonized ITA harvesting on intrasternal microcirculation is unknown. Intraskeletal tissue perfusion has been proven to be crucial for deep wound healing. Furthermore, the impact of different levels of surgical preparation quality on intrasternal microcirculation has not been investigated yet.

METHODS

Sternal microcirculation (sLDP) was monitored with a novel Laser Doppler Perfusion needle probe, while the ITA was skeletonized in a pig model. To mimic different levels of preparation quality, satellite veins were either coagulated or not during preparation. To show the effect of ideally avoiding any surgical manipulation on sLDP, the ITA was clipped in a third sham-harvested group.

RESULTS

sLDP was reduced highly significant to 71 [standard deviation (SD): 9]% (P < 0.001) after skeletonized harvesting of the ITA. Coagulation of the satellite veins as a detrimental surgical factor resulted in a significantly stronger reduction of sLDP to 56 (SD: 11)% (P < 0.05) compared to sLDP with non-coagulated satellite veins. ITA clipping reduced sLDP highly significant to 71 (SD: 8)% (P < 0.001) in the sham-operated group.

CONCLUSIONS

ITA harvesting markedly impairs microcirculation of the sternum but remains unavoidable when coronary artery bypass grafting should be performed. Nevertheless, excessive surgical damage and coagulation of satellite veins is avoidable and should be reduced to a minimum to minimize the risk of deep sternal wound healing complications.

Clinical Application of the Internal Mammary Artery Perforator Adipofascial Flap

Background:

Skin ulcers on the anterior chest wall are caused mainly by radiation therapy for breast cancer and anterior mediastinitis after thoracotomy, and they are often refractory. Some muscle flaps are commonly used for anterior chest wall reconstruction, but muscle flaps accompany high invasion. We used the internal mammary artery perforator (IMAP) adipofascial flap and IMAP skin flap for the anterior chest wall reconstruction.

Methods:

We examined the IMAPs using a handheld Doppler device and contrast-enhanced computerized tomography preoperatively. Each flap was designed based on the location of the IMAP and the size of the flap was dependent on the coverage required by the size and location of the skin ulcer. The location of the IMAPs functioned as the pivot point of the flap and the flap was flipped or swung on the defect.

Results:

We used IMAP adipofascial flap for 2 cases and IMAP skin flap for 1 case. In those 3 cases, we could elevate the flap with no complications even after the internal mammary artery had been harvested. There was no recurrence of the skin ulcer or wound infection after the operation.

Conclusions:

In this study, we reported 3 cases of skin ulcer on the anterior chest wall reconstructed with the IMAP adipofascial and skin flap. To our knowledge, this is the first report of the use of the IMAP flap as an adipofascial flap. The IMAP adipofascial flap accompanies less invasion than muscle flaps and the surgical procedure is relatively easy. The IMAP adopofascial flap is considered as one of the effective means for anterior chest wall reconstruction.

Wireless vitals-Proof of concept for wireless patient monitoring in an emergency department setting

Vital sign assessment is a common task in emergency medicine, but resources for continuous monitoring are restricted, data is often recorded manually, and entangled wires cause frustration. Therefore, we designed a small, wireless photoplethysmographic device capable of continuously assessing pulse, respiratory frequency and oxygen saturation on the sternum and tested the performance and feasibility in an emergency department setting. Fifty (56.3 ± 20.2 years), consenting emergency patients (29 male) were recruited. Heart rate, respiratory rate and oxygen saturation were recorded simultaneously using the device and standard monitoring equipment. Data was compared using Bland-Altman plotting (heart rate, respiratory rate) and mean difference (oxygen saturation). The bias for heart- and respiratory rate was 0.4 (limits of agreements -11.3, 12.2 and -6.1, 7.0). Mean difference for oxygen saturation was -0.21 ± 2.35%. This may be the first wireless device to use photoplethysmography on the sternum for vital sign assessment. We noted good agreement with standard monitors, but lack of standardization in data processing between monitoring systems may limit the generalizability of these findings. Although further improvements are needed, the feasibility of this approach provides proof of concept for a new paradigm of large scale, wireless patient monitoring.

The risk of mediastinitis and deep sternal wound infections with single and bilateral, pedicled and skeletonized internal thoracic arteries

Bilateral internal thoracic artery (BITA) grafting may prolong survival in coronary artery bypass graft (CABG) patients, but its use has been curtailed due to concerns of deep sternal wound infections (DSWI) resulting in mediastinitis. This article examines the association of single internal thoracic artery (SITA) and BITA grafting and the role of harvesting techniques with the development of DSWI in CABG patients. The development of DSWI following BITA grafting is multifactorial and is independent of the harvesting technique.

The 'Two Bridges Technique' for sternal wound closure. The use of vacuum-assisted closure for the treatment of deep sternal wound defects: a centre-specific technique

The objective is to describe the 'Two Bridges Technique' (TBT), which has proven to be successful and has been the standard technique at our centre for vacuum-assisted closure (VAC) of post-sternotomy mediastinitis. An extensive literature search was performed in four databases to identify all published articles concerning VAC for post-sternotomy mediastinitis. Several VAC methods have been used; however, no article has described our specific technique. TBT consists of a two-bridges construction using two types of foam with different pore sizes, which ensures an equally divided negative pressure over the wound bed and stabilisation of the chest. This guarantees a continuous treatment of the sternal defect and prevents foam displacement. It maintains an airtight seal that prevents skin maceration and provides enough protection to avoid right ventricular rupture. The main advantage of TBT is the prevention of shifting or tilting of the foam during chest movements such as breathing or couching. Along with targeted antibiotic treatment, this alternative VAC technique can be an asset in the sometimes cumbersome treatment of post-sternotomy mediastinitis.

Sterile Necrosis of the Sternum: A Rare Complication Following Coronary Artery Bypass Surgery

We herein present the unique case of a 68-year-old male diabetic patient who developed sterile necrosis of the sternum 1 month after myocardial revascularization with the use of bilateral internal thoracic artery grafts. The sternum had been closed by the bilateral Robicsek wiring technique. The sternum was removed, and bilateral pectoralis major flaps were used to cover the defect. The patient had an uneventful recovery.

A randomized comparison of flow characteristics of semiskeletonized and pedicled internal thoracic artery preparations in coronary artery bypass

Background

Harvesting the internal thoracic artery (ITA) with semiskeletonization is an alternative technique between conventional wide pedicle and skeletonization. It is almost as simple as pedicle harvesting; however, it is supposed to provide the advantage of graft flow and length. Since the heart is unique being the only organ which is perfused during diastole, for comparing the intraoperative graft flow characteristics of semiskeletonization and pedicle technique, we used diastolic filling (DF) using transit-time flow measurement as a primary result. The objective of this study is to compare if semiskeletonized ITA has a greater effect on the intraoperative DF of graft flow versus conventional pedicled ITA in coronary artery bypass.

Methods

Between July 2015 and May 2016, a prospective evaluation of 60 consecutive patients undergoing coronary artery bypass grafting for left anterior descending artery revascularization were randomized to having semiskeletonized (n = 30) or conventional pedicled (n = 30) ITA graft harvested by the same surgeon. Intraoperative transit-time flows were obtained. The DF of the ITA graft at the end of operation was evaluated in two groups.

Results

The intraoperative DF was significantly greater in the semiskeletonized grafts than in the pedicled grafts (70.50 ± 14.15 versus 57.6 ± 19.39%; p = 0.005). No statistical difference was observed comparing quantitative pulsatile flow and pulsatile index at the end of the operation in the two groups. However, the free flow of the conduit during the cardiopulmonary bypass before the anastomosis performed was greater in semiskeletonized group than in pedicled group (94 ± 48.37 versus 56.35 ± 34.90 ml/min; p = 0.003). The total operative time was comparable between two groups (p = 0.092).

Conclusions

Semiskeletonized ITA resulted in superior DF of left anterior descending bypass graft flow as compared with pedicled ITA. It is also provide a greater free flow and length of the graft without the long-delayed operative time.

Trial registration

Trial registration number (Study ID): TCTR20160913002

Date of registration: September 10, 2016

Robotically Assisted Minimally Invasive Off-Pump Coronary Artery Bypass Surgery in a Patient With Permanent Tracheostomy

BACKGROUND

Patients with a permanent tracheostomy requiring coronary surgery represent a unique challenge, being at increased risk of sternal wound complications, mediastinitis and stoma necrosis. Several techniques have been described including manubrium sparing sternotomy, thoracoscopic internal mammary harvest and hybrid revascularisation.

METHODS

We report a case of robotic assisted (daVinci^®Xi™ Surgical System) total arterial off-pump revascularisation in a patient with previous laryngectomy and permanent tracheostomy. The main advantage of this approach was to minimise the risk of postoperative sternal complication and mediastinatis, whilst still providing the prognostic benefit of total arterial grafting and the neurological advantage of the aorta no-touch technique.

A Review of Differing Techniques of Mammary Artery Harvesting on Sternal Perfusion: Time for a Randomized Study?

The use of internal mammary artery (IMA) grafts for coronary artery bypass may devascularize the sternum. We performed a literature review by searching the PubMed database for studies that assessed sternal perfusion after IMA harvesting. The majority of papers describe various techniques and compared (1) IMA harvest versus no IMA harvest, (2) single versus bilateral, and (3) skeletonized versus pedicled. Evidence is inconclusive as to whether single harvesting causes significant devascularisation and whether this is increased with bilateral harvesting. Sternal ischemia may also be a transient phenomenon. However, skeletonization may preserve perfusion more than pedicled harvesting, particularly in diabetic patients.

Pleural subxyphoid drain confers better pulmonary function and clinical outcomes in chronic obstructive pulmonary disease after off-pump coronary artery bypass grafting: a randomized controlled trial

Objective

To evaluate the lung function and clinical outcome in severe chronic obstructive pulmonary disease in patients undergoing off-pump coronary artery bypass grafting with left internal thoracic artery graft, comparing the pleural drain insertion in the intercostal versus subxyphoid region.

Methods

A randomized controlled trial. Chronic obstructive pulmonary disease patients were randomized into two groups according pleural drain site: II group (n=27) - pleural drain in intercostal space; SI group (n=29) - pleural drain in the subxyphoid region. Spirometry values (Forced Vital Capacity - and Forced expiratory volume in 1 second) were obtained on preoperative and 1, 3 and 5 postoperative days. Chest x-ray from preoperative until postoperative day 5 (POD5) was performed for monitoring respiratory events, such as atelectasis and pleural effusion. Pulmonary shunt fraction and pain score was evaluate preoperatively and on postoperative day 1.

Results

In both groups there was a significant decrease of the spirometry values (Forced Vital Capacity and Forced expiratory volume in 1 second) until POD5 (P<0.05). However, when compared, SI group presented less decrease in these parameters (P<0.05). Pulmonary shunt fraction was significantly lower in SI group (P<0.05). Respiratory events, pain score, orotracheal intubation time and postoperative length of hospital stay were lower in the SI group (P<0.05).

Conclusion

Subxyphoid pleural drainage in severe Chronic obstructive pulmonary disease patients determined better preservation and recovery of pulmonary capacity and volumes with lower pulmonary shunt fraction and better clinical outcomes on early postoperative off-pump coronary artery bypass grafting.

Factors influencing the diameter of human anterior and posterior intercostal arteries

At present, there have not been any detailed studies examining the size relationships of the intercostal arteries. This study was carried out to investigate the relationship between the vessel lumenal diameter of ipsilateral, paired anterior and posterior IC arteries, as well as with the length of the IC space supplied by each artery. Samples were collected from the second-sixth anterior and posterior IC arteries near their site of origin, and the lengths of the corresponding IC spaces were measured in 42 cadavers. Lumenal diameters of both the anterior and posterior IC arteries at consecutive IC space closely followed second degree polynomial regression models (R(2) = 0.9655, and R(2) = 0.9741, respectively), and reached maximum size at the fifth IC space, which was found to be the longest of the IC spaces. No direct relationship was observed between diameters of the paired anterior and posterior IC arteries, although there was a trend for the larger anterior IC arteries to be paired with the larger posterior IC arteries. The calculated rate of blood flow at each IC artery was approximately two-fold greater in males than in females. These results suggest that the length of the IC space, and hence the extent of the thoracic wall supplied, is a major factor in determining the diameter of both anterior and posterior IC arteries. Since COPD is such a prevalent disease, this study also examined its influence on the IC arteries, and found that the posterior IC arteries are significantly larger among afflicted subjects.

Coronary Revascularization Using Bilateral Internal Thoracic Arteries: Safe with Skeletonization?

Substantial evidence exists to support a long-term survival benefit with bilateral internal thoracic artery (BITA) revascularization in coronary artery bypass grafting. However, this technique remains grossly underutilized worldwide and especially in the United States. In this review, we discuss evidence for the advantages of BITA grafting as well as the associated the risk of sternal wound complications. We then review a growing body of literature that suggests 'skeletonization' of the internal thoracic artery during harvest confers a protective benefit against sternal wound infection in patients receiving BITA.

Laser Doppler flowmetry assessment of peristernal perfusion after cardiac surgery: beneficial effect of negative pressure therapy

Negative pressure therapy has been successfully applied to clean, closed incisions in patients at high-risk for wound complications. Using laser Doppler flowmetry, we evaluated peristernal perfusion after cardiac surgery via median sternotomy, assessing the influence of mammary artery harvesting and the impact of negative pressure therapy. Twenty adult patients underwent median sternotomy for cardiac surgery followed by routine closure. Negative pressure was applied at 125 mm Hg for 4 days postoperatively in patients with increased risk for wound complications (n = 10, negative pressure group); standard dressings were applied to control incisions postoperatively (n = 10). Presternal perfusion was determined at baseline and daily for 4 days postoperatively using laser Doppler flowmetry. Results within and between groups were compared with analysis of variance. No wound complications were encountered in either group. Perfusion increased among the patients who underwent negative pressure therapy and decreased among the controls (P = 0.004). Mammary artery harvesting reduced peristernal perfusion by 25.7% in the controls, but negative pressure increased perfusion by 100% after mammary harvesting (P = 0.04). Negative pressure therapy increased perfusion relative to controls and compensated for reduced perfusion rendered by mammary artery harvesting, providing additional support for 'well wound therapy' in high-risk patients.

A novel technique of coronary revascularization in porcelain aorta: report of two cases

Severe atherosclerosis of the distal ascending aorta increases the risk of intraoperative stroke during coronary artery bypass. More than one in situ arterial graft is required to avoid aortic manipulation during proximal anastomosis. The application of bilateral internal thoracic arteries is a good choice, but it also carries the risk of sternal wound complications. Using a composite graft constructed with a partially harvested in situ right internal thoracic artery graft and another vascular conduit prevents extreme ischemia of the sternum. This study describes the experience of successful coronary revascularization using bilateral internal thoracic arteries and modified with a composite graft in two patients with a severely atherosclerotic ascending aorta.

Influence of pleurotomy on pulmonary function after off-pump coronary artery bypass grafting

BACKGROUND

This study evaluated the influence of pleurotomy on pulmonary function after off-pump coronary artery bypass grafting (CABG) using the left internal thoracic artery (LITA).

METHODS

Thirty patients were prospectively allocated into two groups: 15 patients with an opened left pleural cavity (OP group) and 15 patients with an intact pleural cavity (IP group). Bedside pulmonary function tests were recorded preoperatively and on postoperative days 1, 3, and 5. Arterial blood gas analyses and ratio of partial pressure of arterial oxygen (PaO2/fraction of inspired oxygen (FiO2) ratio were evaluated preoperatively and on postoperative day 1.

RESULTS

A significant decrease of pulmonary function was observed in both groups until postoperative day 5. When compared with the percentage of the preoperative value, the forced vital capacity was significantly lower in the OP group than in the IP group on postoperative days 1 (33.3% +/- 8.3% versus 49.1% +/- 8.4%, p < 0.001), 3 (45.4% +/- 7.0% versus 62.1% +/- 8.6%, p < 0.001), and 5 (56.1% +/- 8.7% versus 77.5% +/- 11.6%, p < 0.001). Similar results were found for forced expiratory volume in 1 second on postoperative days 1 (35.7% +/- 8.6% versus 50.0% +/- 9.8%, p < 0.001), 3 (48.4% +/- 7.0% versus 61.5% +/- 9.02%, p < 0.001) and 5 (58.8% +/- 8.5% versus 75.9% +/- 10.2%, p < 0.001). The PaO2 value and the PaO2/FiO2 ratio dropped on postoperative day 1 in both groups (p < 0.05), with a higher fall in the OP group (p < 0.05). Orotracheal intubation time (p = 0.012) and hospital stay (p = 0.002) were lower in the IP group.

CONCLUSIONS

Off-pump CABG using the LITA, independently of pleural opening, induced a significant reduction in early postoperative pulmonary function. However, the patients undergoing pleurotomy demonstrated more pronounced pulmonary dysfunction.