Left Ventricular Assist Device Thrombosis: Combined Approach by Echocardiography and Logfiles Review for Diagnosis and Management.

INTRODUCTION: Left ventricular assist devices are an established therapy for end-stage heart failure. Follow-up of these patients showed complications, such as thrombosis. Our objective was to evaluate the contribution of echocardiography - in association with HeartWare HVAD online logfiles reviews and lactate dehydrogenase titration - for diagnosis and treatment of thrombosis. METHODS: Seventeen episodes of thrombosis were diagnosed in 8/20 patients with HVAD. Diagnosis was made by trans-thoracic echocardiographic blood flow velocities, logfiles review of power consumption and pump flows, and titration of lactate dehydrogenase. Data were collected at baseline routine control (Group A), during thrombosis (Group B), after thrombolysis (Group C). RESULTS: Thrombolysis was successful in all cases; one patient died of cerebral haemorrhage. Echocardiographic maximal blood flow velocity near the inflow cannula was 598±42 cm/sec (Group B), 379.41±21 cm/sec (Group C), and 378.24±28 cm/sec (Group A) (P<0.00001). In eight (47%) cases, thrombi were visualized in the left ventricle by three-dimensional modality. Logfiles recordings of blood flows were 9.52±0.9 L/min (Group B), 4.02±0.4 L/min (Group C), and 4.04±0.4 L/min (Group A) (P<00001). Power consumption was 5.01±0.7 W (Group B), 3.45±0.2 W (Group C), and 3.46±0.2 W (Group A) (P<0.00001). Lactate dehydrogenase was 756±54 IU (Group B), 234±22 IU (Group A), and 257±36 IU (Group C) (P<0.00001). CONCLUSIONS: Echocardiography of increased maximal velocity near the inflow cannula is a sign of HVAD obstruction. Logfile reviews provide a clear picture of HVAD obstruction. Combination of echocardiographic data and review of logfiles detects signs of left ventricular assist devices thrombosis leading to a successful treatment.

Left Ventricular Assist Device Thrombosis: Combined Approach by Echocardiography and Logfiles Review for Diagnosis and Management

ABSTRACT Introduction: Left ventricular assist devices are an established therapy for end-stage heart failure. Follow-up of these patients showed complications, such as thrombosis. Our objective was to evaluate the contribution of echocardiography — in association with HeartWare HVAD online logfiles reviews and lactate dehydrogenase titration — for diagnosis and treatment of thrombosis. Methods: Seventeen episodes of thrombosis were diagnosed in 8/20 patients with HVAD. Diagnosis was made by trans-thoracic echocardiographic blood flow velocities, logfiles review of power consumption and pump flows, and titration of lactate dehydrogenase. Data were collected at baseline routine control (Group A), during thrombosis (Group B), after thrombolysis (Group C). Results: Thrombolysis was successful in all cases; one patient died of cerebral haemorrhage. Echocardiographic maximal blood flow velocity near the inflow cannula was 598±42 cm/sec (Group B), 379.41±21 cm/sec (Group C), and 378.24±28 cm/sec (Group A) (P<0.00001). In eight (47%) cases, thrombi were visualized in the left ventricle by three-dimensional modality. Logfiles recordings of blood flows were 9.52±0.9 L/min (Group B), 4.02±0.4 L/min (Group C), and 4.04±0.4 L/min (Group A) (P<00001). Power consumption was 5.01±0.7 W (Group B), 3.45±0.2 W (Group C), and 3.46±0.2 W (Group A) (P<0.00001). Lactate dehydrogenase was 756±54 IU (Group B), 234±22 IU (Group A), and 257±36 IU (Group C) (P<0.00001). Conclusions: Echocardiography of increased maximal velocity near the inflow cannula is a sign of HVAD obstruction. Logfile reviews provide a clear picture of HVAD obstruction. Combination of echocardiographic data and review of logfiles detects signs of left ventricular assist devices thrombosis leading to a successful treatment.

Novel Technique for Percutaneous Retrieval of a U-kinked Impella Catheter.

We present a new technique for percutaneous retrieval of a U-kinked displaced Impella catheter. First we used the hooker from the left femoral artery to snare the catheter tip. Both catheter and hooker were pulled down simultaneously from 2 opposite sites until the U-kinking sat astride the aortic bifurcation. Finally the loop was straightened by pulling both catheter and hook. Once unfolded the hook was released, and the catheter was retrieved easily from the right femoral artery. This technique is highly reproducible because of several advantages. It is easy to perform, takes a short time, does not require special devices, and is not expensive.

Deceptive appearance of a rapidly growing left atrial myxoid sarcoma with pancreatic metastasis.

The third case reported in the literature of a left atrial neoplasm characterized by a very deceptive, low grade cellular component at its early stage of growth, so as to be diagnosed as a myxoma is presented. Two months after surgical excision, regrowth of the mass occurred, producing a pancreatic mass also. The new atrial mass was excised; a left atrial myxoid sarcoma and a pancreatic metastasis were diagnosed. One week later the atrial sarcoma grew again. This time surgery was contraindicated and the patient underwent chemotherapy with a satisfactory control of the sarcoma growth. The myxoid sarcoma may present with the deceptive appearance of a myxoma in their early stages. Therefore, patients who have undergone surgical removal of a myxoma should have a close follow-up to monitor unexpected malignant turnover.

The Effect of Different Water Temperatures on Retention Loss and Material Degradation of Locator Attachments.

PURPOSE: To examine the changes in Locator attachments after exposure to different water temperatures and cyclic loading. MATERIALS AND METHODS: Four groups of pink Locator attachments (3.0 lb. light retention replacement patrix attachments; 10 per group) were soaked for the equivalent of 5 years of use in distilled water at the following temperatures: 20°C, 37°C, 60°C. One group was kept dry to test the effect of water. A universal testing machine was used to measure the retention force of each treated attachment during 5500 insertion and removal cycles, simulating approximately 5 years of use. The results were compared using Kruskal-Wallis one-way ANOVA by ranks. Surface changes of tested attachments were examined using scanning electron microscopy (SEM). RESULTS: The exposure to 60°C water significantly increased the percentage of retention loss in Locator attachments (p < 0.05) compared to the 20°C water group and significantly reduced the final retention force compared to the other groups (p < 0.05). SEM examinations revealed severe cracking and material degradation in Locator attachments after exposure to 60°C water and cyclic loading, which were not evident in other groups. Cracking was observed after exposure to 60˚C water before cyclic loading. CONCLUSIONS: Exposure to 60°C water, potentially similar to denture cleansing procedures, could cause cracking in Locator attachments. Cracking is associated with hydrolytic degradation of nylon at 60°C. The change in structure could result in a significant loss of retention.

The influence of interimplant divergence on the retention characteristics of locator attachments, a laboratory study.

PURPOSE: The aim of the study was to assess the influence of interimplant divergence on retention of two Locator attachments before and after in vitro simulation of 3 to 5 years of use. MATERIALS AND METHODS: A hydraulic universal testing machine was used to measure the retention of two blue Locator attachments during 5500 seating and unseating cycles. Ten pairs of Locators were tested with interimplant divergences of 0°, 10°, and 20°. Scanning electron microscopy (SEM) was used to examine surface changes of the components. The results were tested with ANOVA and Bonferroni post hoc correction when normally distributed. Results that were not normally distributed were tested with Kruskal-Wallis one-way ANOVA by ranks. RESULTS: At the start of the experiment the 10° group showed significantly more retention than the 0° group, but no significant difference was found between the 0° and 20° groups or the 10° and 20° groups. After 5500 cycles, there was no significant difference in retention between any of the groups. The SEM images showed an approximately equal amount of wear in the nylon patrix inserts from all the groups. CONCLUSIONS: The retention of Locator pairs was not impaired by interimplant divergence of up to 20°. Retention after 5500 removal cycles was less than the initial retention in all groups. The nylon Locator patrices showed wear defects of similar location, type, and magnitude in the SEM images, regardless of interimplant angulation.

Acute obstruction by Pannus in patients with aortic medtronic-hall valves: 30 years of experience.

BACKGROUND: Acute dysfunction of mechanical aortic valve prostheses is a life-threatening adverse event. Pannus overgrowth, which is fibroelastic hyperplasia originating from the periannular area, is one cause of dysfunction. The aim of this study was to determine the annual incidence of readmittance resulting from acute obstruction caused by pannus during 30 years of observation in patients with Medtronic-Hall aortic valve prostheses and to analyze the risk factors associated with pannus development. METHODS: From 1982 to 2004, 1,187 patients in our department underwent aortic valve replacement with Medtronic-Hall mechanical monoleaflet valve prostheses. As of December 31, 2012, 27 of these patients (2.3%) had presented with acute valve dysfunction caused by pannus obstruction. RESULTS: The annual incidence of pannus was 0.7 per 1,000. The median time from the primary operation to prosthetic dysfunction was 11.1 years (range, 1.2 to 26.8 years). Of the 20 patients who underwent reoperation, 2 died. Seven patients died before reoperation. Women had a higher risk for the development of obstructing pannus, and patients with pannus obstruction were younger. Valve size was not an independent risk factor. CONCLUSIONS: Women and younger patients are at higher risk for pannus development. When acute dysfunction by pannus is suspected in a mechanical aortic valve, an immediate echocardiogram and an emergency aortic valve replacement should be carried out because of the potential of a fatal outcome.

Acetylsalicylic acid treatment until surgery reduces oxidative stress and inflammation in patients undergoing coronary artery bypass grafting.

OBJECTIVES: Acetylsalicylic acid (ASA) is a cornerstone in the treatment of coronary artery disease (CAD) due to its antiplatelet effect. Cessation of aspirin before coronary artery bypass grafting (CABG) is often recommended to avoid bleeding, but the practice is controversial because it is suggested to worsen the underlying CAD. The aims of the present prospective, randomized study were to assess if ASA administration until the day before CABG decreases the oxidative load through a reduction of inflammation and myocardial damage, compared with patients with preoperative discontinuation of ASA. METHODS: Twenty patients scheduled for CABG were randomly assigned to either routine ASA-treatment (160 mg daily) until the time of surgery (ASA), or to ASA-withdrawal 7 days before surgery (No-ASA). Blood-samples were taken from a radial artery and coronary sinus, during and after surgery and analysed for 8-iso-prostaglandin (PG) F2α; a major F2-isoprostane, high-sensitivity C-reactive protein (hs-CRP), cytokines and troponin T. Left ventricle Tru-Cut biopsies were taken from viable myocardium close to the left anterior descending artery just after connection to cardiopulmonary bypass, and before cardioplegia were established for gene analysis (Illumina HT-12) and immunohistochemistry (CD45). RESULTS: 8-Iso-PGF2α at baseline (t1) were 111 (277) pmol/l and 221 (490) pmol/l for ASA and No-ASA, respectively (P = 0.065). Area under the curve showed a significantly lower level in plasma concentration of 8-iso-PGF2α and hsCRP in the ASA group compared with the No-ASA group with (158 pM vs 297 pM, P = 0.035) and hsCRP (8.4 mg/l vs 10.1 mg/l, P = 0.013). All cytokines increased during surgery, but no significant differences between the two groups were observed. Nine genes (10 transcripts) were found with a false discovery rate (FDR) <0.1 between the ASA and No-ASA groups. CONCLUSIONS: Continued ASA treatment until the time of CABG reduced oxidative and inflammatory responses. Also, a likely beneficial effect upon myocardial injury was noticed. Although none of the genes known to be involved in oxidative stress or inflammation took a different expression in myocardial tissue, the genetic analysis showed interesting differences in the mRNA level. Further research in this field is necessary to understand the role of the genes.

Impact of competitive flow on wall shear stress in coronary surgery: computational fluid dynamics of a LIMA-LAD model.

AIMS: Competitive flow from native coronary vessels is considered a major factor in the failure of coronary bypass grafts. However, the pathophysiological effects are not fully understood. Low and oscillatory wall shear stress (WSS) is known to induce endothelial dysfunction and vascular disease, like atherosclerosis and intimal hyperplasia. The aim was to investigate the impact of competitive flow on WSS in mammary artery bypass grafts. METHODS AND RESULTS: Using computational fluid dynamics, WSS was calculated in a left internal mammary artery (LIMA) graft to the left anterior descending artery in a three-dimensional in vivo porcine coronary artery bypass graft model. The following conditions were investigated: high competitive flow (non-significant coronary lesion), partial competitive flow (significant coronary lesion), and no competitive flow (totally occluded coronary vessel). Time-averaged WSS of LIMA at high, partial, and no competitive flow were 0.3-0.6, 0.6-3.0, and 0.9-3.0 Pa, respectively. Further, oscillatory WSS quantified as the oscillatory shear index (OSI) ranged from (maximum OSI = 0.5 equals zero net WSS) 0.15 to 0.35, <0.05, and <0.05, respectively. Thus, high competitive flow resulted in substantial oscillatory and low WSS. Moderate competitive flow resulted in WSS and OSI similar to the no competitive flow condition. CONCLUSION: Graft flow is highly dependent on the degree of competitive flow. High competitive flow was found to produce unfavourable WSS consistent with endothelial dysfunction and subsequent graft narrowing and failure. Partial competitive flow, however, may be better tolerated as it was found to be similar to the ideal condition of no competitive flow.

Pulsatility index variations using two different transit-time flowmeters in coronary artery bypass surgery.

OBJECTIVE: Transit-time flow measurement is widely accepted as an intra-operative assessment in coronary artery bypass grafting (CABG). However, the two most commonly applied flowmeters, manufactured by MediStim ASA and Transonic Inc., have different default filter settings of 20 and 10 Hz, respectively. This may cause different flow measurements, which will influence the reported results. The aim was to compare pulsatility index (PI) values recorded by the MediStim and Transonic flowmeters in two different clinical settings: (1) analysis of the flow patterns recorded simultaneously by both flowmeters in the same CABGs; and (2) evaluation of flow patterns under different levels of filter settings in the same grafts. METHODS: Graft flow and PI were measured using the two different flowmeters simultaneously in 19 bypass grafts. Finally, eight grafts were assessed under different digital filter settings at 5, 10, 20, 30, 50 and 100 Hz. RESULTS: The Transonic flowmeter provided substantially lower PI as compared with the MediStim flowmeter. By increasing the filter setting in the flowmeter, PI increased considerably. CONCLUSIONS: The Transonic flowmeter displayed a lower PI than the MediStim, due to a lower filter setting. In the Transonic,flow signals are filtered at a lower level, rendering a 'smoother' pattern of flow curves. Because different filter settings determine different PIs, caution must be taken when flow values and flowmeters are compared. The type of flowmeter should be indicated whenever graft flow measurements and derived indexes are provided [corrected].

A technique to verify or correct analogue position and soft tissue profile on an implant working cast.

A procedure which allows verification of the implant working cast and a method to correct the position of one or more implant analogues, if necessary, is described. In a single procedure, a corrected, accurate cast with soft tissue profile can be obtained by using a polyether impression material in conjunction with an acrylic resin jig. (J Prosthet Dent 2009;102:137-139).

Different graft flow patterns due to competitive flow or stenosis in the coronary anastomosis assessed by transit-time flowmetry in a porcine model.

OBJECTIVE: To assess whether coronary graft flow patterns are affected differently by native coronary competitive flow or by stenosis of the coronary anastomosis. METHODS: Nine pigs (65-70 kg) underwent off-pump grafting of the left internal mammary artery to the left anterior descending artery (LAD). Transit-time flow patterns in the mammary grafts were recorded under four different conditions: (1) baseline flow (proximal LAD occluded), (2) full competitive flow, (3) partial competitive flow and (4) after creation of a stenosis in the anastomosis. Competitive flow was achieved by an adjustable occluder on the left anterior descending artery. The mean luminal stenosis of the anastomosis was 75+/-11%, calculated by epicardial ultrasound. Mean flow, systolic and diastolic antegrade and retrograde flow during different flow conditions were calculated as ratios of baseline flow and compared. Different derived flow indexes were calculated and compared in the same manner. Friedman's test and post hoc analyses by Wilcoxon signed-ranks were performed without correction for multiple comparisons. RESULTS: Mean graft flow was more reduced by competitive flow than by a stenotic anastomosis of 75+/-11%. Competitive flow significantly decreased diastolic antegrade flow and both diastolic and systolic maximum peak flows, but increased retrograde flow, compared with baseline and stenosis. Furthermore, competitive flow and stenosis could be distinguished by analysis of several derived indexes. Pulsatility index (maximum-minimum flow/mean flow) and insufficiency percent (retrograde flow as fraction of total flow) was increased significantly more by competitive flow than by stenosis. Diastolic filling percent was significantly reduced at competitive flow compared with stenosis and baseline. CONCLUSIONS: The mammary graft flow was significantly reduced by native coronary competitive flow, but marginally decreased by a stenotic anastomosis of 75% mean luminal stenosis. Reduction of graft flow due to competition was particularly evident in diastole. A detailed flow pattern analysis may differentiate between competitive flow and stenosis of the anastomosis.

Transit-time blood flow measurements in sequential saphenous coronary artery bypass grafts.

BACKGROUND: Little information is available on transit-time flow measurements of sequential saphenous vein grafts. The aim of the study was evaluation of mean blood flow and pulsatility index of sequential saphenous vein grafts in a large population of patients operated on with coronary artery bypass grafting. METHODS: In 581 patients 1,390 grafts were nested into left internal mammary artery to left anterior descending artery, single vein grafts, or double and triple sequential vein grafts, and analyzed. RESULTS: Within the single vein graft group there were no differences between flow of grafts to different target vessels except for diagonals (diagonal versus obtuse marginal, p < 0.001; versus posterior descending artery, p = 0.035; versus right coronary artery, p = 0.003). Flows measured in single vein grafts were significantly lower than in double (p < 0.001) and triple sequential vein grafts (p < 0.001). Flows were lower in double versus triple sequential vein grafts (p = 0.017) and higher in men versus women (p < 0.001). Mean pulsatility index of vein grafts were lower in the left versus the right coronary system, 2.0 +/- 0.01 and 2.4 +/- 0.06, respectively (p < 0.001). Between sex and groups of vein grafts within each coronary system, mean pulsatility index had similar values. CONCLUSIONS: Blood flow increases from single to double and up to triple sequential grafts. Single grafts directed to diagonals have the lowest flow. Graft blood flows are higher in male versus female patients. Single, double, and triple saphenous vein grafts have similar pulsatility indexes. Pulsatility index of grafts to the right coronary system is significantly higher than that of grafts to the left coronary system.

Is unilateral antegrade cerebral perfusion equivalent to bilateral cerebral perfusion for patients undergoing aortic arch surgery?

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was whether unilateral antegrade cerebral perfusion is equivalent to bilateral cerebral plegia for cerebral protection during aortic arch surgery. Altogether 233 papers were found using the reported search, of which 17 presented the best evidence to answer the clinical question. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results, and study weaknesses of these papers are tabulated. These papers documented antegrade selective cerebral perfusion in a total of 3548 patients: bilateral cerebral perfusion in 2949 patients and unilateral perfusion in 599 patients. Both methods of cerebral perfusion resulted in neurological injury rates of <5%, but the period of antegrade cerebral perfusion allowed by bilateral perfusion was significantly higher. While unilateral perfusion allowed around 30-50 min, bilateral perfusion allowed 86 to over 164 min of ASCP with an acceptably low CVA rate. Therefore, we conclude that while both methods are acceptable, once the ASCP time is expected to rise over 40-50 min, bilateral cerebral perfusion is the technique that is best documented to be safe.

Blood flow imaging: a new two-dimensional ultrasound modality for enhanced intraoperative visualization of blood flow patterns in coronary anastomoses.

OBJECTIVES: The study's objective was to evaluate a novel two-dimensional ultrasound imaging modality termed "blood flow imaging" (BFI) for intraoperative assessment of blood flow patterns in coronary anastomoses. The BFI modality extends color Doppler imaging (CDI) with information on flow direction and velocity that is not limited by angle dependency or aliasing artifacts. METHODS: Intraoperative ultrasound recordings of patent left internal mammary artery-left anterior descending anastomoses were acquired from an experimental porcine model (N = 9). Three independent observers randomly evaluated CDI and BFI cineloops with regard to different assessments of flow direction and velocity. Further, a selection of technical problems that might occur in clinical practice was induced in three pigs to investigate the resulting flow patterns. RESULTS: The BFI modality was found to provide an improved visual assessment of blood flow patterns in the left internal mammary artery-left anterior descending anastomosis compared with CDI. CONCLUSION: The modality may therefore increase the certainty and efficiency of flow evaluation for intraoperative quality control in coronary surgery.

Narrowing effect of off-pump CABG on the LIMA-LAD anastomosis: epicardial ultrasound assessment.

AIM: Effects of off-pump CABG on LIMA-LAD anastomotic dimensions vs. on-pump CABG assessed by epicardial ultrasound imaging. MATERIAL AND METHODS: LIMA-LAD anastomoses were performed off-pump in 38 patients and on-pump in 12. Intra-operative imaging was by a GE Vivid 7 ultrasound scanner and i13L transducer. Length of the anastomosis (DA), LAD diameters at the toe (D1) and heel (D3) of the anastomosis, the reference downstream LAD (D2) were measured in diastole by two-dimensional imaging (B-mode). Relationships between these dimensions were compared between on- and off-pump patients. RESULTS: In off-pump patients, D3 dimension was smaller than D1 (p=0.004). Both D3 and D1 were smaller than D2 (p<0.01). Ratio D3/D2 was smaller than D1/D2 (p=0.009). In on-pump patients, these ratios were similar. D3/D2 ratio was smaller in off- than in on-pump patients (p=0.01), D1/D2 were similar in the two groups. CONCLUSION: Off-pump CABG may cause a narrowing of the coronaries, especially at the anastomotic heel. The anastomotic technique at the heel may have to be modified to improve its patency.