MATERIALS AND METHODS The four adult cardiac and vascular surgery hospitals identified as hubs were the Centro Cardiologico Monzino (Monzino), San Raffaele Hospital, Legnano Hospital and Poliambulanza Brescia. Each hub had its own spokes for cardiac and vascular surgery [16] (Fig. 1). San Donato Hospital was the paediatric cardiac surgery hub. Figure 1: Diagram of the hub-and-spoke system. (A) Interconnections between cardiovascular surgery hubs that cooperate and exchange information during weekly briefings. (B) Interconnections between a cardiac surgery hub and its spokes. (C) Interconnections between vascular surgery hub and its spokes. The surgical pathways had three simultaneous surgical teams on call at all times (two independent cardiac teams and one vascular team). Three different pathways were created: one for COVID-19-negative patients (green path), one for patients waiting for the screening result (pink path) and one for COVID-19-positive patients (red path). The postoperative ICU was split into two areas by a new dividing wall to create physical separation between COVID-19-positive and -negative patients. All procedures were carried out according to shared Italian Society of Cardiac Surgery Recommendations [17]. Hub-and-spoke and regional coordination The first step was to coordinate the different hubs. To ensure sharing of the workload, resources and surgical priorities, a weekly briefing was held among all the hubs. The goal was to obtain an update on the number of ICU beds available among the hubs, because the access rate to each area was unprecedented and unpredictable (Monzino, up to 11; San Raffaele, up to 20; Legnano, up to eight; and Poliambulanza Brescia, up to six) and on the number of operations to be performed and to share ongoing strategies and surgical indications. Surgical priorities and screening The second step involved setting up a new surgical waiting list that was shared between the hub and its own spokes. In the pre-COVID-19 era, each hospital scheduled its own referred patients using an institutional waiting list. This waiting list always took into account the recommendations of the National Health Care System: high priority patients, i.e. those with rapidly progressing diseases, were in class A (mandatory hospitalization within 30 days), whereas class B–D patients had less severe clinical presentations, were without priority and were on 60-day, 180-day and 12-month waiting lists, respectively [18]. At present, in this war-like reality, only class A cases, defined as ND, were included on a new hub-and-spoke shared waiting list and were treated independently from the cases deemed urgent and emergency. The overall criteria listed in Table 1 were defined by a task force of expert cardiovascular surgeons from all hub-and-spoke networks and were in agreement with EuroSCORE emergency/urgent definitions and in agreement with Italian Health Organization recommendations [19]. Table 1: Definitions of emergency, urgent and non-deferrable cardiac and vascular cases in the coronavirus disease 2019 era Pathology Indications Aortic disease Acute aortic dissection/intramural haematoma (exclusion criteria: age >80 years; coma; stroke; visceral organ malperfusion) Ascending aortic aneurysm ≥60 mm Ascending aortic aneurysm 55–60 mm in Marfan syndrome, yearly growth >5 mm, uncontrolled arterial hypertension Severe aortic stenosis Symptomatic for syncope, angina, NYHA functional class IIIb–IV Severe aortic regurgitation Acute pulmonary oedema with left ventricular dysfunction or haemodynamic instability Severe mitral stenosis Haemodynamic instability or acute pulmonary oedema Acute mitral regurgitation Papillary muscle or chordal rupture determining acute pulmonary oedema Cardiac ischaemic disease Cardiac rupture or acute interventricular defect Untreatable unstable angina Left main coronary artery stenosis >70% Subocclusive stenosis of left main coronary artery or anterior interventricular coronary artery Acute endocarditis Emergency (guidelines criteria) Urgent (guidelines criteria) Prosthesis dysfunctions Heart failure Urgent if non-dischargeable Masses Left atrial myxoma Other masses with high embolic risk Acute limb ischaemia Ruptured aneurysm Chronic limb ischaemia Leriche III–IV grade Thoracic and thoraco-abdominal aorta Diameter >7 cm Rapid growth (>1 cm in 6 months) Lesion instability at CT scan (blister, fissuring thrombus) Abdominal aorta Diameter >6.5 cm Rapid growth (>1 cm in 6 months) Lesion instability on CT scan (blister, fissuring thrombus) Carotid stenosis Symptomatic Stenosis >90%, monolateral and asymptomatic Ulcerated plaque CT: computed tomography; NYHA: New York Heart Association. Each urgent or scheduled patient had a mandatory screening for SARS-CoV-2, which always included a chest computed tomography (CT) scan, nasal swab, corporal temperature monitoring and blood tests. The clinical discussion and daily surgical programme for ND patients included all members of the telematic heart team (THT), one goal being to allow surgeons from the spokes to perform surgery on their own referred patients in the hub. Daily morning briefings were held internally at the Monzino hospital to monitor every aspect of all in-patients (COVID-19 status, number of available beds) and to share news from the Health Care Lombardy Regional System and the national government. Pathway organization Each new patient was considered COVID-19-positive and kept isolated in a dedicated hospital area called the ‘pink area’ while waiting for the screening result. If the screening result was negative (negative medical history for suspected contact, absence of fever or interstitial pneumonia on a chest CT scan, negative results from the nasal swab), the patient was transferred to the ‘green area’ (COVID-19-free area). If the test results were positive (chest CT scan indicative of interstitial pneumonia and/or positive results from the nasal swab), the patient was transferred to a dedicated zone called the ‘red area’, a separate zone with physical barriers and heavy use of personal protective equipment to protect working personnel, where only patients with COVID-19 were hospitalized. Emergency and urgency In case of emergency or urgency (Fig. 2), the on-call surgeon could choose between two strategies: either wheel the patient rapidly to the operating room or keep the patient in the emergency room (ER) for further assessment. In both cases, the nasal swab and the CT scan were performed in the shortest possible time. Thanks to our internal laboratory, the swabs results were obtained within 3 h or before the end of the operation in the case of an emergency procedure. Figure 2: Flow chart for emergency and urgent cases. COVID: coronavirus disease; ICU: intensive care unit. In cases of emergency surgery, the patient was considered and treated as positive for SARS-CoV-2 by the health care staff, who wore personal protective equipment, until screening results were available. At the end of the procedure, depending on the screening result, the patient was transferred to the appropriate dedicated ICU area. In cases of urgent surgery, the patient was screened and held in a pink area (in the ER), isolated from other patients until the results were available. If the results of the screening test were positive, the surgical indication had to be confirmed by the THT and the procedure was possibly postponed if clinical conditions allowed. Non-deferrable patients A different flow chart was designed for ND cases (Fig. 3). Cases were discussed in the THT. If the patient presented from home, the screening was performed upon arrival and the patient was kept in the pink waiting area. Once the screening result was available, non-COVID-19 patients were transferred to the green area, whereas patients with COVID-19 were evaluated according to clinical status: Rehospitalization was foreseen after the quarantine period with a new COVID-19 screening or, in the case of a poor clinical condition, the patient was transferred to a COVID-19 centre for further care. Figure 3: Flow chart for non-deferrable cases. COVID: coronavirus disease; OR: operating room. If the ND patient was referred from another hospital (a spoke), a first COVID screening was performed before arranging transfer: a second screening was performed upon arrival in the pink area. Negative patients were moved to the green area to wait for a surgical procedure. Patients positive for COVID-19 were transferred back to the spoke/COVID-19 centre for therapy. The THR discussion, with the reasons for acceptance or refusal of the surgical indications, was recorded in a dedicated database that was updated by the hub staff.