Transit time flow measurement (TTFM) is a quality control tool for intraoperative graft evaluation in coronary artery bypass graft (CABG) surgery. A critical review of the literature available using TTFM in CABG surgery is the focus of this article. The main objectives will be to detail precise parameters for flow evaluation, to show limitations of TTFM and to prove its predictive impact on postoperative graft failure rate. Publications listed in the PubMed database were reviewed, searching for intraoperative graft verification in coronary surgery by TTFM, with postoperative imaging follow-up (FU) modality and with a special focus on publications released after European guidelines from 2010. Nine included publications revealed an overall graft failure rate of ∼12%. Mean graft flow had a positive predictive value in the largest study, and cut-offs, of at least 20 ml/min for internal mammary artery (IMA) grafts, therein partially confirming guidelines, and 30-40 ml/min for saphenous venous grafts (SVGs) were proposed. An explicit correlation between graft flow, patency rate and severity of coronary stenosis, by indicating the fractional flow reserve, was found for IMA grafts. Increased pulsatility index and increased systolic reverse flow probably predict worse outcome and may help identifying competitive flow. Diastolic filling, rarely indicated, could not be confirmed as the predictive marker. No significant correlation of TTFM and graft failure rate for radial and other arterial grafts could be found, partially due to the small number of these types of grafts analysed. Larger target vessels and lower postoperative CK-MB levels may predict better graft patency rates. Low sensitivity for TTFM to reliably detect graft failure is certainly a major issue, as found in randomized analyses. However, methodical limitations and varying threshold values for TTFM render a general consensus difficult. Influence of quantity (vessel territory distribution) and quality (myocardial scar) of the graft perfusion area, on TTFM and FU outcome, was not included by anyone and should be part of future research. TTFM is probably not the tool of choice to detect progressive late graft failure of SVG. Peroperative TTFM values should be correlated with one type of conduit, differentiating between early and late graft failure (by applying a uniform, appropriated definition), to precise and confirm threshold values.
Reoperations for SVD after bioprosthesis implantation occurred exclusively among younger patients (<56 years), not suitable for systemic anticoagulation. Previous studies, together with our experience, are in favour of an age limit between 56 and 60 years, taking into consideration alternative transcatheter approaches to SVD treatment.
OBJECTIVES Current guidelines recommend prophylactic replacement of the ascending aorta at an aneurysmal diameter of >55 mm to prevent acute Type A aortic dissection (TAAD) in non-Marfan patients. Several publications have challenged this threshold, suggesting that surgery should be performed in smaller aneurysms to prevent this devastating disease. We reviewed our experience with measuring aortic size at the time of TAAD to validate the existing recommendation for prophylactic ascending aorta replacement. METHODS All patients who had been admitted for TAAD to our emergency department from 2014 to 2019 and underwent ascending aorta replacement were included. Marfan patients were excluded. The maximum diameter of the dissected aorta was measured preoperatively using CT scan. We estimated the aortic diameter at the time of dissection to be 7 mm smaller than the measured maximum diameter of the dissected aorta (modelled pre-dissection diameter). RESULTS Overall, 102 patients were included. Of these, 67 were male (65.6%) and 35 were female (34.4%), and the cohort’s mean age was 65 ± 12.1 years. In addition, 66% were treated for arterial hypertension. The mean maximum modelled pre-dissection diameter was 39.6 ± 4.8 mm: 39.1 ± 5.1 mm in men and 40.7 ± 2.8 mm in women (P = 0.1). The cumulative 30-day mortality rate was 19.6% (20/102). CONCLUSIONS TAAD occurred at a modelled aortic diameter below 45 mm in 87.7% of our patients. Therefore, the current aortic diameter threshold of 55 mm excludes ∼99% of patients with TAAD from prophylactic replacement of the ascending aorta. The maximum diameter of the ascending aorta warrants reappraisal and this parameter should be a distinct part of a personalized decision-making process that also takes into account age, gender and body surface area to establish the surgical indication for preventive aorta replacement aimed to improve the survival benefit of this procedure.
Predominant etiologies for type A dissection in young patients are connective tissue diseases, BAV, severe hypertension, vascular diseases and cocaine abuse. Early in-hospital mortality rate was low and principally influenced by massive myocardial infarction due to coronary dissection as well as severe neurological disorders. Aortic root dilatation after a prosthetic ascending aortic replacement was the main re-operation cause and occurred earlier during follow-up than arch or more distal aortic dilatation. Surgical ascending aortic repair for type A dissection in young patients is lifesaving with excellent long-term survival.
Right ventricular (RV) rupture in cases of mediastinitis following cardiac surgery is a rare and dangerous complication. Bleeding from the right ventricle occurs mainly after sternal reopening, due to either iatrogenic manipulation (wire removal, lesions due to wiring maneuvers) or mechanical shearing forces, producing direct injury. We present a case of RV wall perforation due to infection in a recurrent postoperative mediastinitis with a closed chest. The current literature on treatment of postoperative mediastinitis is also reviewed.
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