Sex differences in vascular reactivity of coronary artery bypass graft conduits.

Females have increase in-hospital mortality and poorer outcomes following coronary artery bypass grafting (CABG). Biological differences in the reactivity of the graft conduits to circulating catecholamine may contribute to this sex difference. This study examined sex differences in the vasoconstrictor responses of internal mammary artery (IMA) and saphenous vein (SV) conduits to phenylephrine (PE) and endothelin-1 (ET-1). Functional IMA and SV were obtained from 78 male and 50 female patients undergoing CABG (67.7 ± 11 and 69 ± 10 years, respectively) and subjected to the following experimental conditions. (1) Concentration response curves for PE and ET-1 were generated in an intact IMA and SV and endothelium denuded IMA segments, (2) in the presence of the nitric oxide synthase inhibitor (L-NAME) or the cyclooxygenase inhibitor (indomethacin) in an endothelium-intact IMA and (3) the activity state (abundance and phosphorylation) of the α1-adrenergic receptor was investigated using Phos-tag™ western blot analysis. (1) Compared to male, female IMA and SV were hypersensitive to PE but not ET-1 (p < 0.05). The female IMA hypersensitivity response to PE was abolished following endothelial denudation, (2) persisted in the presence of L-NAME but was abolished in the presence of indomethacin and (3) there was no sex differences in the abundance and phosphorylation of the α1-adrenergic receptor in IMA. Female IMA and SV graft conduits are hypersensitive to α1-adrenergic stimuli. This endothelial cyclooxygenase pathway-mediated hypersensitivity may produce excessive IMA and SV graft constriction in females administered catecholamines and could contribute to their poorer CABG outcomes.

Surgeon's Focussed Ultrasound Examination of the Long Saphenous Vein Reduces Surgical Time and Wound Complications.

BACKGROUND: Despite increased use of arterial grafts, the long saphenous vein (LSV) is often utilised as conduit for coronary artery bypass graft (CABG). Preoperative ultrasound (U/S) vein assessment is limited to patients with varicosities, clinical signs suggestive of poor vein conduits and a history of cardiac or vascular surgery. The aim of this study was to evaluate the usefulness and logistics of the surgeon incorporating intraoperative U/S assessment of the LSV into their regular practice. METHODS: All patients undergoing coronary artery revascularisation and open vein harvest in our institution were recruited from July 2016 to February 2017. Demographics, including known risk factors for wound complications were documented, in addition to surgical details such as harvest time, vein length and surgical repairs of the conduit. Focussed U/S assessment was performed intraoperatively by the surgical registrar before beginning the procedure. The diameter of the leg pre and postoperatively, as well as the incidence, type and severity of wound complications were documented for further statistical analysis. RESULTS: A total of 103 patients were included in this study. Two patients died perioperatively and were excluded from the study. The remaining 101 patients were separated in two cohorts-U/S group (n=32) and blind technique group (n=69). Demographics were similar between the groups, whilst other risk factors for harvest complications, such as presence of superficial varicosities on clinical examination and renal failure were significantly more frequent in the U/S group. The median harvest time was significantly lower within the U/S group (25 mins versus 40 mins; p=0.001), as was the rate of overall wound complications (6.2% vs 23.2%; p=0.04). CONCLUSIONS: Ultrasound assessment of the LSV by the surgical team intraoperatively is feasible, easy to learn and does not demand extra costs or delays. It significantly reduces surgical harvest time and it is associated with a reduced incidence of wound complications, swelling and postoperative mobility impairment.

Dynamic four-dimensional computed tomography (4D CT) imaging for re-entry risk assessment in re-do sternotomy - first experience.

BACKGROUND: Repeat cardiac surgeries are well known to have higher rates of complications, one of the important reasons being injuries associated with re-do sternotomy. Routine imaging with CT can help to minimise this risk by pre-operatively assessing the anatomical relation between the sternum and the underlying cardiovascular structures, but is limited by its inability to determine the presence and severity of functional tethering and adhesions between these structures. However, with the evolution of wide area detector MD CT scanners, it is possible to assess the presence of tethering using the dynamic four-dimensional CT (4D CT) imaging technique. METHODS: Nineteen patients undergoing re-do cardiac surgery were pre-operatively imaged using dynamic 4D CT during regulated respiration. The datasets were assessed in cine mode for presence of differential motion between sternum and underlying cardiovascular structures which indicates lack of significant tethering. RESULTS: Overall, there was excellent correlation between preoperative imaging and intraoperative findings. The technique enabled our surgeons to meticulously plan the procedures and to avoid re-entry related injuries. CONCLUSIONS: Our initial experience shows that dynamic 4D CT is useful in risk stratification prior to re-do sternotomy by determining the presence or absence of tethering between sternum and underlying structures based on assessment of differential motion. Furthermore we determined the technique to be superior to non-dynamic assessment of retrocardiac tethering.

Starting and finishing a cardiac case: Sternotomy, hemostasis, and closure.

The cardiac multimedia literature is abundant, but a significant gap exists in educational videos demonstrating routine essential steps such as the sternotomy or the closure. These components are common and carry significant mortality and morbidity should a sternal complication occur, highlighting the importance for the cardiothoracic surgeon to master these steps.

The radial artery: Open harvesting technique.

The radial artery is an important conduit in coronary artery surgical revascularization due to its robust long-term clinical outcomes. The use of the radial artery has become popularized in recent times. Therefore it is essential for junior surgeons to master harvest techniques that are safe, reliable, and easy to replicate.

Beating heart minimally invasive mitral valve surgery in patients with previous sternotomy: the operative technique and early outcomes.

Objective: Reoperative mitral valve surgery is increasingly required and can be associated with significant morbidity and mortality. The beating heart minimally invasive mitral valve surgery has a proposed benefit in avoiding the risks of repeat sternotomy, with reducing the need for adhesiolysis and cardioplegia reperfusion injury. We describe our experience with such a technique in patients with previous sternotomy. Methods: A retrospective study was performed and all patients undergoing surgery of mitral valve through a right limited thoracotomy without application of an aortic cross-clamp (beating heart) as a redo cardiac surgery between January 2006 and January 2015 were included (n=25). Perioperative data as well as the operative technique are presented. Results: Six patients (24%) had two previous sternotomies and one (4%) had three previous sternotomies. Mitral valve repair was performed in 11 patients (44%). No patient required conversion to median sternotomy. Inotropic support beyond 4 hours after operation was required in seven patients (28%). Ventilation time was less than 12 hours in 14 patients (56%) with another six patients (24%) extubated within 24 hours after surgery. Postoperative course was complicated with cerebrovascular accident in two patients (8%). In-hospital mortality was 4% (n=1). There was no 30-day mortality after discharge. Conclusions: Reoperative mitral valve surgery can be safely performed through a limited right thoracotomy approach on a beating heart while on full cardiopulmonary bypass. The technique can be associated with potentially shorter operation, shorter cardiopulmonary bypass and a less complicated recovery.

Mechanisms Responsible for Serotonin Vascular Reactivity Sex Differences in the Internal Mammary Artery.

BACKGROUND: The increased adverse cardiac events in women undergoing coronary artery bypass grafting are multifactorial and may include clinical, psychosocial, and biological factors. Potential contributing biological factors could include vascular hyperreactivity of the internal mammary artery (IMA) to endogenous vasoconstrictors in women, resulting in a predilection to myocardial ischemia. This study evaluated sex differences in serotonin and thromboxane A2 dependent vasoconstriction in human isolated IMA, with the mechanistic role of (1) the endothelium, (2) nitric oxide (NO), (3) prostaglandins, and (4) receptor activity investigated for any observed sex difference. METHODS AND RESULTS: Viable isolated human IMA segments were obtained from 116 patients (44 women [mean age, 66.8±12.2 years] and 72 men [mean age, 66.6±10.4 years]) undergoing coronary artery bypass grafting. Cumulative concentration-response curves for serotonin and thromboxane A2 mimetic, U46619, were determined and revealed an increased sensitivity to serotonin but not U46619 in women. This sex difference to serotonin was further assessed by the following: (1) endothelial denudation, (2) endothelial NO synthase inhibition and NO quantification using electron paramagnetic resonance, (3) cyclooxygenase inhibition and prostaglandin metabolite quantification using mass spectrometry, and (4) quantification of receptor activity status. The female hyperreactivity to serotonin was (1) abolished by endothelial denudation; (2) unaffected by NO synthase inhibition, with no difference in electron paramagnetic resonance-assessed NO levels; (3) abolished by cyclooxygenase inhibition (quantification of prostaglandins in IMA revealed a trend towards reduced 6-keto prostaglandin F1α in female IMA; P=0.08); and (4) unrelated to receptor activity. CONCLUSIONS: These data indicate that female IMAs are hyperreactive to serotonin but not U46619, with the former attributable to an endothelium-dependent cyclooxygenase pathway.

Video-assisted thoracoscopy in the management of intrapleural extravasation of cytotoxic chemotherapy.

The extravasation of cytotoxic agents into subcutaneous tissue is a serious complication of chemotherapy. Unfortunately, if such extravasation occurs into the pleural space, limited data is available to guide appropriate management. We present the first report in the literature of video-assisted thoracoscopy combined with a topoisomerase II inhibitor and iron chelator, dexrazoxane, in the successful management of this complication.

Gastrointestinal complications after cardiac surgery: 10-year experience of a single Australian centre.

BACKGROUND: Gastrointestinal (GI) complications after cardiac surgery are uncommon, but are associated with high morbidity and mortality as well as significant hospital resource utilization. METHODS: We analysed a prospectively collected database containing all adult cardiac surgery procedures performed from July 2001 to March 2011 at Monash Medical Centre and Jessie McPherson Private Hospital. Patients with post-operative GI complications were compared to patients without GI complications who were operated in the same period. RESULTS: The incidence of GI complications was 1.1% (61 out of 5382 patients) with an overall 30-day mortality of 33% (versus 3% in the non-GI complication group). The most common complications were GI bleeding, gastroenteritis and bowel ischaemia. Patients who had GI complications were significantly older, had higher incidence of renal impairment, chronic lung disease and anticoagulation therapy and were more likely to be in cardiogenic shock. Emergency procedures, combined coronary artery bypass grafting and valve surgery and aortic dissection cases were more common in the GI complication group. The GI complication group also had higher incidence of return to theatre, renal failure, stroke, septicaemia and multi-organ failure. CONCLUSIONS: GI complications after cardiac surgery remain an uncommon but dreadful complication associated with high mortality. Our findings should prompt a high degree of clinical vigilance in order to make an early diagnosis especially in high risk patients. Further studies aiming to identify independent predictors for GI complications after cardiac surgery are warranted.

Custodiol versus blood cardioplegia in complex cardiac operations: an Australian experience.

OBJECTIVES: A single or dual-dose strategy for myocardial protection is attractive in long operations, in avoiding the need to interrupt the procedure to re-administer cardioplegia. We hypothesized that a single administration of Bretschneider histidine-tryptophan-ketoglutarate (HTK) crystalloid solution (Custodiol) offers myocardial protection comparable with repeated tepid blood cardioplegia. METHODS: We reviewed a prospectively compiled single-centre database containing all adult cardiac procedures performed from January 2005 to January 2011. Preoperative demographic and investigative data, operative variables and postoperative (30-day) mortality and morbidity were compared between the Custodiol and blood cardioplegia groups. The study primary endpoints were 30-day mortality, return to the operating theatre, myocardial infarction, stroke, postoperative requirement for an intra-aortic balloon pump, new renal failure, prolonged ventilation and re-admission to hospital within 30 days. Propensity score matching was performed to correct for any bias that may have been associated with the usage of Custodiol. RESULTS: A total of 1900 cardiac surgical procedures were identified of which 126 (7%) utilized Custodiol and 1774 (93%) used blood cardioplegia as the primary cardioplegic agent. After propensity-score matching, we were able to match 71 Custodiol cases one-to-one to those receiving blood cardioplegia. There were no statistically significant differences noted for any of the endpoints studied after propensity-score matching. In particular, the proportion of mortality (blood cardioplegia: 1 vs Custodiol 4%, P = 0.63) any mortality/morbidity (blood cardioplegia: 35 vs Custodiol: 39% P = 0.46) was similar between the groups. CONCLUSIONS: The use of Custodiol is convenient, simple and at least as safe as tepid blood cardioplegia for myocardial protection in complex cardiac operations. A randomized prospective comparison of myocardial protection strategies is warranted.

Baroreflex control of heart rate by oxytocin in the solitary-vagal complex.

Previous work demonstrated that oxytocinergic projections to the solitary vagal complex are involved in the restraint of exercise-induced tachycardia (2). In the present study, we tested the idea that oxytocin (OT) terminals in the solitary vagal complex [nucleus of the solitary tract (NTS)/dorsal motor nucleus of the vagus (DMV)] are involved in baroreceptor reflex control of heart rate (HR). Studies were conducted in male rats instrumented for chronic cardiovascular monitoring with a cannula in the NTS/DMV for brain injections. Basal mean arterial pressure and HR and reflex HR responses during loading and unloading of the baroreceptors (phenylephrine/sodium nitroprusside intravenously) were recorded after administration of a selective OT antagonist (OT(ant)) or OT into the NTS/DMV. The NTS/DMV was selected for study because this region contains such a specific and dense concentration of OT-immunoreactive terminals. Vehicle injections served as a control. OT and OT(ant) changed baroreflex control of HR in opposite directions. OT (20 pmol) increased the maximal bradycardic response (from -56 +/- 9 to -75 +/- 11 beats/min), whereas receptor blockade decreased the bradycardia (from -61 +/- 13 to -35 +/- 2 beats/min). OT(ant) also reduced the operating range of the reflex, thus decreasing baroreflex gain (from -5.68 +/- 1.62 to -2.83 +/- 1.05 beats x min(-1) x mmHg(-1)). OT injected into the NTS/DMV of atenolol-treated rats still potentiated the bradycardic responses to pressor challenges, whereas OT injections had no effect in atropine-treated rats. The brain stem effect was specific because neither vehicle administration nor injection of OT or OT(ant) into the fourth cerebral ventricle had any effect. Our data suggest that OT terminals in the solitary vagal complex modulate reflex control of the heart, acting to facilitate vagal outflow and the slowdown of the heart.