Tomislav Klokočovnik

Understanding coronary artery bypass transit time flow curves: role of bypass graft compliance

OBJECTIVESnLow mean bypass graft flow (Q) and high pulsatility index (PI) measured by the transit time flow measurement method are not specific for anastomotic stenosis, but occur with competitive flow and poor coronary run-off. We hypothesized that graft compliance is responsible for these changes and that flow measured at the proximal end of the coronary bypass can be viewed as a sum of the graft capacitive flow and flow that passes through the distal anastomosis.nnnMETHODSnTransit time flow measurements (TTFMs) of 15 left internal thoracic artery (LITA) to LAD bypass grafts and 10 saphenous vein grafts (SVGs) to either the right coronary artery (RCA) or posterior descending artery (PDA) were analysed. The TTFM was performed on the proximal and distal end of the graft, and proximally with distal occlusion of the graft. Low mean bypass graft flow PI and diastolic filling (DF) measured distally and proximally were compared, and graft compliance was estimated.nnnRESULTSnDiastolic filling was higher distally in every single case (LITA-LAD: distal DF 76 ± 12% vs proximal 66 ± 13%, P = 0.005; SVG-RCA/PDA: distal 72 ± 15% vs proximal 63 ± 12%, P = 0.018). There were no significant differences in Q and PI. Subtracting the distal from the proximal flow gave a result identical to the proximal TTFM in distally occluded grafts, confirming the presence of graft capacitive flow. Graft compliance estimated from the flow of distally occluded grafts was 0.99 ± 0.47 μl/mmHg for LITA grafts and 0.78 ± 0.42 μl/mmHg for SVG grafts.nnnCONCLUSIONSnThe study confirmed that the TTFM measured at the proximal end of the coronary bypass could be viewed as a sum of graft capacitive flow and the flow that passes through the distal anastomosis. Graft capacitive flow increases the systolic and decreases the diastolic TTFM when measured at the proximal end of the graft. It explains the higher DF when the TTFM is measured at the distal end of the graft and the increase in the PI at the proximal end when Q decreases. As the influence of graft capacitive flow on the PI in low Q can be eliminated by performing the TTFM at the distal end of the graft, we believe that the value of PI is clinically irrelevant.

Cardiac autotransplantation and extracellular matrix patch reconstruction for a left atrial sarcoma

1Department of Cardiology, University Medical Center Ljubljana, Ljubljana, Slovenia 2Department of Cardiovascular Surgery, University Medical Center Ljubljana, Ljubljana, Slovenia 3 Faculty of Medicine, Institute of Pathology, University of Ljubljana, Ljubljana, Slovenia Correspondence Jure Dolenc PhD, University Medical Center Ljubljana, Zaloška 7, Ljubljana 1000, Slovenia. Email: jure.dolenc@kclj.si Funding information No sources of funding were used for the presented work.

Minimally Invasive Sternotomy for Aortic Valve Replacement Followed by a Minilaparotomy for Abdominal Aneurysm Repair

Abdominal aortic aneurysms (AAAs) are commonly associated with severe coronary artery disease, but the incidence of associated aortic valve disease and AAAs in the general population is not known. The standard approach for surgical repair of AAAs is a laparotomy, and for aortic valve repair, a full sternotomy; results of both approaches are well documented. However, when AAAs and aortic valve disease occur concomitantly and both are symptomatic, they should be repaired during a combined procedure, with the aortic valve repair performed first. We describe the case of a 75-year-old patient with a symptomatic infrarenal AAA and severe aortic valve stenosis. To avoid an extensive surgical incision and shorten the recovery period, we performed a combined procedure in which we replaced the aortic valve through a ministernotomy and repaired the AAA through a minilaparotomy. The postoperative period was uneventful, and the patient was discharged home 6 days after surgery.

Minimally invasive aortic valve replacement under thoracic epidural anesthesia in a conscious patient: case report.

Cardiopulmonary bypass and full median sternotomy have been recognized as major morbidity factors in cardiac surgery. Additional morbidity factors are general anesthesia and endotracheal intubation. Over the past several years high-thoracic epidural anesthesia (hTEA) has emerged as a potentially beneficial supplement to general anesthesia in the care of patients undergoing cardiac surgery. We report a case of ministernotomy aortic valve replacement performed with hTEA. The procedure was not converted to general anesthesia or to a conventional operation and was performed without adverse incidents. The patient was discharged from the hospital on the 2nd postoperative day. There were no complications within 30 days after surgery. This case demonstrates that thoracic epidural anesthesia without endotracheal intubation used for aortic valve replacement performed through ministernotomy is feasible. Further experience is necessary to determine the safety of this method and the effect on outcome.

Restrictive versus Standard Fluid Regimen in Elective Minilaparotomy Abdominal Aortic Repair—Prospective Randomized Controlled Trial

Objectiveu2003Elective minilaparotomy abdominal aortic aneurysm (AAA) repair is associated with a significant number of complications involving respiratory, cardiovascular, gastrointestinal, and central nervous systems, with mortality ranging up to 5%. In our study, we tested the hypothesis that intra- and postoperative intravenous restrictive fluid regimen reduces postoperative morbidity and mortality, and improves the outcome of minilaparotomy AAA repair. Methodsu2003From March 2009 to July 2013, 60 patients operated due to AAA were included in a prospective randomized controlled trial (RCT). About the administration of fluid during the operation and in the early postoperative period, all the patients were randomized into two groups: the group of standard fluid administration (S-group, 30 patients) and the group of reduced fluid administration (R-group, 30 patients). The verification of the treatment success was measured by the length of intensive care unit (ICU) stay, duration of hospitalization after the procedure, as well as the number and type of postoperative complications and mortality. This prospective RCT was registered in a publicly accessible database ClinicalTrials.gov with unique Identifier ID: NTC01939652. Resultsu2003Total fluid administration and administration of blood products were significantly lower in R-group as compared with S-group (2,445.5 mL vs. 3308.7 mL, pu2009=u20090.004). Though the number of nonlethal complications was significantly lower in R-group (2 vs. 9 patients, pu2009=u20090.042), the difference in lethal complications remained nonsignificant (0 vs. 1 patient, pu2009=u2009ns). The average ICU stay (1.2 vs. 1.97 days, pu2009=u20090.003) and duration of postoperative hospital stay (4.33 vs. 6.20 days, pu2009=u20090.035 for R-group and S-group, respectively) were found to be significantly shorter in R-group. Conclusionu2003Intra- and postoperative restrictive intravenous fluid regimen in patients undergoing minilaparotomy AAA repair significantly reduces postoperative morbidity, and shortens ICU and overall hospital stay. Even though incidence of lethal complication was lower in R-group, the difference did not reach statistical significance. Therefore, we may assume that this study was probably underpowered to estimate the differences in mortality between R- and S-groups. Further multicentric, sufficiently powered RCTs are needed to confirm these findings and to clarify effect of restrictive fluid management on mortality.

A giant sternum-eroding aneurysm of the ascending aorta and aortic arch.

Background: Giant aneurysms of the ascending aorta, defined as aneurysms of more than 10 cm in diameter, are a rare finding. They represent a high risk of dissection or rupture and can also compress the surrounding structures and organs. Generally, the only effective treatment is surgery.nCase report: In this report we present a case of a giant sternum-eroding aneurysm of the ascending aorta and aortic arch in a progressively dyspnoic 34-year old female and describe a stepwise surgical approach as the optimal treatment. Conclusion: Surgical treatment of giant aneurysms of the ascending aorta carries high morbidity and mortality particularly when compressing the surrounding structures or causing bone erosion. A stepwise surgical approach with the establishment of CPB and hypothermia prior to sternotomy, precise surgical technique, and meticulous postoperative care are the factors which significantly improve the safety and efficacy of the procedure and all contribute to a better outcome.

Tracheal pressure regulated volume assist ventilation in acute respiratory failure

PurposeProportional assist ventilation (PAV) uses volume assist (VAV) and flow assist ventilation (FAV) to reduce elastic and resistive effort, respectively. Proportional assist ventilation may be difficult to apply clinically, particularly due to FAV related considerations. It was hypothesized that regulating tracheal (Ptr) rather than airway opening pressure (Pao), to overcome endotracheal tube related resistive effort, during VAV would provide an effective alternative method of ventilation. We therefore compared the effects of Pao and Ptr regulated VAV on breathing pattern and inspiratory effort.MethodsIn seven intubated patients, flow, volume, Pao, Ptr, esophageal and transdiaphragmatic pressure were measured during VAV (0-80% respiratory system elastance) using Pao vs Ptr to regulate ventilator applied pressure. Breathing pattern and the pressure-time integral of the inspiratory muscles (∫Pmus·dt) and diaphragm (∫Pdi·dt) were determined.ResultsCompared to spontaneous breathing, the respiratory rate to tidal volume ratio, or rapid shallow breathing index (RSBI), improved progressively with increasing VAV (130 ± 64 vs 70 ± 35, VAV 0 vs 80%; P < 0.05) while inspiratory effort fell (∫Pmus·dt = 39.6 ± 7.5 vs 28.5 ± 7.2 cm H2O·sec·L−1,∫Pdi·dt, = 35.4 ± 7.8 vs 24.2 ± 5.9 cm H2O·sec·L−1, VAV 0 vs 80%; P < 0.05) due to a decrease in elastic related effort. At any given level of support, there was further reduction in RSBI, ∫Pmus·dt, and ∫Pdi·dt (which averaged 23.6 ± 2.7, 33.7 ± 4.4, and 38.5 ±5.1%, respectively; P < 0.05) for Ptr compared to Pao regulated VAV due to a decrease in resistive effort.ConclusionsTracheal pressure regulated VAV can be a simple and effective method of partial ventilatory support in acute respiratory failure. Further work will be needed to determine its efficacy and potential benefit relative to PAV and other modes of ventilation in routine clinical practice.RésuméObjectifsLa ventilation assistée proportionnelle (PAV) a recours à la ventilation volume-assistée (VAV) et à la ventilation débit-assistée (FAV) pour réduire les efforts élastique et résistif, respectivement. La PAV peut être difficile à mettre en pratique cliniquement, surtout à cause de considérations relatives à la FAV. L’hypothèse a été émise que la régulation de la pression trachéale (Ptr) plutôt que de la pression d’ouverture des voies aériennes (Pao), afin de vaincre la résistance de la sonde endotrachéale, durant la VAV serait un mode de ventilation alternatif efficace. Ainsi nous avons comparé les effets de la VAV régulée par Pao et par Ptr sur les courbes respiratoires et l’effort inspiratoire.MéthodesLes mesures suivantes ont été observées chez sept patients intubés : débit, volume, Pao, Ptr, pressions œsophagienne et transdiaphragmatique durant la VAV (0-80 % d’élastance respiratoire) en utilisant soit la Pao, soit la Ptr afin de réguler la pression générée par le respirateur. Les courbes respiratoires et l’intégrale pression-temps des muscles inspiratoires ∫Pmus·dt) et du diaphragme (∫Pdi·dt) ont été déterminées.RésultatsComparé à la respiration spontanée, le ratio fréquence respiratoire : volume courant, ou index de respiration superficielle (RSBI), s’est progressivement amélioré avec une augmentation de la VAV (130 ± 64 vs 70 ± 35, VAV 0 vs 80 %; P < 0,05), alors que l’effort inspiratoire a décru (∫Pmus·dt = 39,6 ± 7,5 vs 28,5 ± 7,2 cm H2O·sec·L−1, ∫Pdi·dt, = 35,4 ± 7,8 vs 24,2 ± 5,9 cm H2O·sec·L-1, VAV0vs80%;P < 0,05) en raison de la diminution de l’effort élastique. A tous les niveaux de soutien, on a observé une diminution plus importante du RSBI, ∫Pmus·dt, et ∫Pdi·dt (atteignant en moyenne 23,6 ± 2,7, 33,7 ± 4,4, et 38,5 ± 5,1 %, respectivement; P < 0,05) pour la VAV régulée par Ptr comparée à celle régulée par Pao en raison de la diminution de l’effort résistif.ConclusionsLa VAV régulée par pression trachéale peut constituer une méthode d’assistance respiratoire partielle simple et efficace dans le cas d’insuffisance respiratoire aiguë. Des travaux supplémentaires seront nécessaires afin de déterminer son efficacité et ses bienfaits potentiels par rapport à la PAV et à d’autres moyens de ventilation mécanique courants dans la pratique clinique.

Intuity™ aortic valve thrombosis

In 2017 a 79-year-old male presented 2 years after biological sutureless aortic valve replacement (IntuityTM, 25mm [Edwards Lifesciences Corporation, Irvine, CA, USA]) and mitral valve repair with worsening heart failure, severe thrombocytopenia and negative hemocultures. Prior to the first procedure in 2015, an echocardiogram showed severe enlargement of the left ventricle, with mild concentric thickening of the walls. Global systolic function of the left ventricle was mildly reduced with left ventricular ejection fraction (LVEF) of 45%. Akinesia of the basal segment of the inferior septum and hypokinesia to akinesia of basal and medial segments of the inferior wall were noticed. Left atrium was also enlarged, while the right chambers appeared of normal size. Coronarography revealed no visible disease or luminal irregularities of coronary arteries with no stenosis of two drug-eluting stents (DES) in the right coronary artery (RCA) that were inserted in 2012. Transthoracic echocardiography (TTE) on admission in 2017 showed symmetrically thickened leaflets of the IntuityTM valve (Fig. 1), maximum pressure gradient (maxPG) of 49mmHg, estimated aortic valve area (AVA) of 0.6cm2 and LVEF of 26%. Due to suspected valve thrombosis low molecular weight heparin (LMWH) treatment was initiated instead of acetylsalicylic acid [1]. After 2 weeks of therapy the leaflets appeared less thickened, with maxPG of 23mmHg and AVA of 1.1cm2 (Fig. 2) and after additional 3 months of therapy the patient was asymptomatic with normal leaflets, maxPG of 18mmHg, AVA of 2.1cm2 (Fig. 3) and LVEF of 33%.

New graft sizing rings for aortic valve reimplantation procedures

OBJECTIVESnThe objective was to design sizing rings that would enable proper sizing of the graft in reimplantation procedures and to perform leaflet repair before graft implantation.nnnMETHODSnThe rings were designed in Autodesk Fusion 360 (San Rafael, CA, USA) and 3D printed using a commercial online 3D printing service. We designed incomplete rings with a low profile and complete rings with a high profile. The complete rings are best suited for reimplantation procedures, whereas low profile C rings are intended for isolated aortic valve repair, where the ascending aorta is not transected. The rings come in sizes corresponding to Vascutek Gelweave graft sizes (Vascutek Terumo, Renfrewshire, Scotland). The ring internal diameters are 5% larger than the designated ring sizes and account for the 5% stretch of the grafts when pressurized. Blades of the rings are placed at 20° intervals. The slits between the blades are designed in such a way that the commissural U-sutures, when put in place and under tension, will lock the ring in position.nnnRESULTSnThe rings were successfully used in 10 of our latest reimplantation procedures. After dissection of the aortic root, the commissures were suspended with U-stitches and then the ring was seated onto them. Complete leaflet repair with plication to achieve adequate effective height was then performed, followed by graft implantation. No additional leaflet repair was needed.nnnCONCLUSIONSnThe newly designed sizing rings enable proper sizing of the graft in reimplantation procedures and enable complete leaflet repair before graft implantation.

Recommendations for the detection and treatment of peripheral arterial disease

In the article, recommendations for the diagnostics in suspected peripheral arterial disease are presentedxa0 together with xa0therapeutic procedures and long- term follow up of the affected patients.