Intra-aortic Balloon Pump Assistance Research Articles

Application of the radial artery after angiography in patients undergoing total arterial coronary revascularization

ObjectiveThere is growing evidence supporting the utilization of the radial artery as a secondary arterial graft in coronary artery bypass grafting (CABG) surgery. However, debates continue over the recovery period of the radial artery following angiography. This study aims to evaluate the clinical outcomes and experiences related to the use of the radial artery post-angiography in total arterial coronary revascularization.MethodsA retrospective analysis was performed on data from patients who underwent total arterial CABG surgery at the University of Hong Kong Shenzhen Hospital from July 1, 2020, to September 30, 2022. Preoperative assessments included ultrasound evaluations of radial artery blood flow, diameter, intimal integrity, and the Allen test. Additionally, pathological examinations of the distal radial artery and coronary artery CT angiography were conducted, along with postoperative follow-up to assess the safety and efficacy of using the radial artery in patients undergoing total arterial CABG.ResultsA total of 117 patients, compromising 102 males and 15 females with an average age of 60.0 ± 10.0 years, underwent total arterial CABG. The internal mammary artery was used in situ in 108 cases, while in 4 cases, it was grafted to the ascending aorta due to length limitations. Bilateral radial arteries were utilized in 88 patients, and bilateral internal mammary arteries in 4 patients. Anastomoses of the proximal radial arteries to the proximal ascending aorta included 42 cases using distal T-anastomosis and 4 using sequential grafts. The interval between bypass surgery and coronary angiography ranged from 7 to 14 days. Pathological examination revealed intact intima and continuous elastic membranes with no significant inflammatory infiltration or hyperplastic lumen stenosis in the radial arteries. There were no hospital deaths, 3 cases of perioperative cerebral infarction, 1 secondary thoracotomy for hemorrhage control, 21 instances of intra-aortic balloon pump (IABP) assistance, and 2 cases of poor wound healing that improved following debridement. CT angiography performed 2 weeks post-surgery showed no internal mammary artery occlusions, but 4 radial artery occlusions were noted.ConclusionUltrasound may be used within 2 weeks post-angiography to assess the recovery of the radial artery in some patients. Radial arteries with intact intima may be considered in conjunction with the internal mammary artery for total arterial coronary CABG. However, long-term outcomes of these grafts require further validation through larger prospective studies.

Application of radial artery in total arterial coronary revascularization in elderly patients

To summarize the application experience and clinical effect of radial artery in total arterial coronary revascularization (TAR) in elderly patients. Retrospectively analyzed the clinical data of patients who underwent TAR at the University of Hong Kong Shenzhen Hospital from July 1, 2020 to May 30, 2022. Patients were divided into ≥ 65-year-old group and < 65-year-old group according to age. The radial artery blood flow, diameter, intimal integrity and Allen test were evaluated by ultrasound before operation. The distal ends of radial artery were collected for pathological examination during operation. Coronary artery CT angiography (CTA) was examined postoperatively and follow up. The safety and reliability of ultrasonic assessment of radial artery and application of radial artery in elderly patients with TAR were summarized and analyzed. A total of 101 patients received TAR, including 35 cases aged ≥ 65 years old, 66 cases aged < 65 years old; 78 cases used bilateral radial arteries, and 23 cases used unilateral radial arteries. 4 cases of bilateral internal mammary arteries. All the proximal ends of the radial artery were anastomosed to the proximal end of the ascending aorta, 34 cases were performed of "Y" grafts, and 4 cases were sequential anastomoses. There was no in-hospital death and perioperative cardiovascular events. Perioperative cerebral infarction occurred in 3 patients. 1 patients was reoperated for bleeding. Intra-aortic balloon pump (IABP) assistance was used in 21 patients. Poor wound healing occurred in 2 cases and healed well after debridement. Follow-up of 2 to 20 months after discharge showed no internal mammary artery occlusion and 4 radial artery occlusions; no major adverse cardiovascular and cerebrovascular event (MACCE) occurred, and the survival rate was 100%. There was no significant difference in the above perioperative complications and follow-up endpoints between the two age groups. By adjusting the order of bypass anastomosis and optimizing the preoperative evaluation method, radial artery combined with internal mammary artery can obtain better outcome early in TAR, and can be safely and reliably applied to elderly patients.

Mindfulness-based stress reduction combined with early cardiac rehabilitation improves negative mood states and cardiac function in patients with acute myocardial infarction assisted with an intra-aortic balloon pump: a randomized controlled trial.

To investigate the clinical effects of mindfulness-based stress reduction (MBSR) intervention combined with early cardiac rehabilitation (CR) on patients with acute myocardial infarction (AMI) assisted with an intra-aortic balloon pump (IABP). A total of 100 AMI patients with IABP assistance due to hemodynamic instability at Wuhan Asia Heart Hospital were enrolled in the study. The participants were divided into two groups using the random number table method (n = 50 each group). Patients receiving routine CR were assigned to the CR control group, while patients receiving MBSR plus CR were assigned to the MBSR intervention group. The intervention was performed twice a day until the removal of the IABP (5-7 days). Each patient's level of anxiety/depression and negative mood state were evaluated before and after intervention using the self-rating anxiety scale (SAS), self-rating depression scale (SDS), and profiles of mood state scale (POMS). The results of the control and intervention groups were compared. IABP-related complications and left ventricular ejection fraction (LVEF), measured with echocardiography, were also assessed and compared between the two groups. The SAS, SDS, and POMS scores were lower in the MBSR intervention group than in the CR control group (P < 0.05). There were also less IABP-related complications in the MBSR intervention group. LVEF was significantly improved in both groups, but the degree of LVEF improvement was more significant in the MBSR intervention group than in the CR control group (P < 0.05). MBSR combined with early CR intervention can assist in alleviating anxiety, depression, and other negative mood states, reduce IABP-related complications, and further improve cardiac function in AMI patients with IABP assistance.

IABP versus Impella Support in Cardiogenic Shock: “In Silico” Study

Cardiogenic shock (CS) is part of a clinical syndrome consisting of acute left ventricular failure causing severe hypotension leading to inadequate organ and tissue perfusion. The most commonly used devices to support patients affected by CS are Intra-Aortic Balloon Pump (IABP), Impella 2.5 pump and Extracorporeal Membrane Oxygenation. The aim of this study is the comparison between Impella and IABP using CARDIOSIM© software simulator of the cardiovascular system. The results of the simulations included baseline conditions from a virtual patient in CS followed by IABP assistance in synchronised mode with different driving and vacuum pressures. Subsequently, the same baseline conditions were supported by the Impella 2.5 with different rotational speeds. The percentage variation with respect to baseline conditions was calculated for haemodynamic and energetic variables during IABP and Impella assistance. The Impella pump driven with a rotational speed of 50,000 rpm increased the total flow by 4.36% with a reduction in left ventricular end-diastolic volume (LVEDV) by ≅15% to ≅30%. A reduction in left ventricular end systolic volume (LVESV) by ≅10% to ≅18% (≅12% to ≅33%) was observed with IABP (Impella) assistance. The simulation outcome suggests that assistance with the Impella device leads to higher reduction in LVESV, LVEDV, left ventricular external work and left atrial pressure-volume loop area compared to IABP support.

Intra-Aortic Balloon Pump During Percutaneous Coronary Intervention in ST-Elevation Myocardial Infarction With High Thrombus Burden and Cardiogenic Shock.

Percutaneous coronary intervention (PCI) in ST-elevation myocardial infarction (STEMI) with high-grade thrombus is a high-risk intervention associated with poor clinical outcomes. Circulatory support with an intra-aortic balloon pump (IABP) during PCI may potentially improve coronary hemodynamics and clinical outcomes in such patients. As existing data on this situation are sparse, we did an observational study to determine short-term outcomes of PCI with IABP support in STEMI patients with high thrombus burden. To determine whether IABP has a potential role in improving outcomes in patients with STEMI with high thrombus burden who are undergoing PCI. Thirty consecutive patients of STEMI with high thrombus burden undergoing PCI with IABP assistance were included. Ninety-three percent of patients had a cardiogenic shock. Clinical and angiographic outcomes assessed include a change in left ventricular ejection fraction (LVEF), 30-day mortality, and assessment of TIMI (thrombolysis in myocardial infarction) flow, TIMI frame count, and TIMI myocardial perfusion grade in the culprit vessel.IABP was initiated before coronary angiography in 36.6% (n=11), between angiography and PCI in 30% (n=9), and after PCI in 33.3% (n=10) of patients. During the 30-dayfollow-up period, 50% (n=15) of patients died. 86.6% (n=13) of survivors had pre-PCI IABP initiation compared to only 46.6% (n=7) among those who died (p=0.020). With pre-PCI IABP initiation (n=20), 30-day mortality was 35% (n=7) compared to 80% (n=8) with post-PCI IABP initiation (n=10) (p=0.020). IABP initiation before PCI in STEMI complicated by cardiogenic shock andhigh angiographic thrombus burden can decrease mortality without any effect on angiographic parameters.

Left Ventricular Pseudoaneurysms Discovered Early After Acute Myocardial Infarction: The Surgical Timing Dilemma.

Left ventricular pseudoaneurysm is a rare disease; it is defined as a ventricular rupture contained by epicardium, pericardial adhesions, or both. It most frequently occurs as a complication of acute myocardial infarction. Surgical treatment is recommended for pseudoaneurysms that are large or symptomatic and for those discovered less than 3 months after myocardial infarction. We report our experience with 2 patients who had left ventricular pseudoaneurysms discovered less than a week after inferior myocardial infarction. Both patients were middle-aged men with right coronary occlusion in whom the diagnoses were established by echocardiography during the first week after infarction. Because both patients were clinically stable, we opted to defer surgery until scarring could facilitate correction; this decision was based on a review of the literature showing that in-hospital mortality is higher with early surgery. The patients were monitored closely in the intensive care unit and were prescribed β-blockers and vasodilators. Both patients underwent left ventricular patch reconstruction with exclusion of the pseudoaneurysm and posterior septum; both received moderate inotropic support and prophylactic intra-aortic balloon pump assistance. Their postoperative courses were uneventful. In 5 prior reports describing 45 patients (13 with acute pseudoaneurysm [≤2 wk after infarction] and 32 with nonacute pseudoaneurysm), in-hospital mortality was 61.5% for patients in the acute group and 15.6% for the nonacute group (P = .0066). We recommend that clinicians consider deferring surgery for patients with stable acute left ventricular pseudoaneurysm to reduce the risks associated with early repair.

Aortic flow below and visceral circulation during aortic counterpulsation: Evaluation of an in vitro model.

This study aimed to test a computer-driven cardiovascular model for the evaluation of the visceral flow during intra-aortic balloon pump (IABP) assistance. The model includes a systemic and pulmonary circulation as well as a heart contraction model. The straight polyurethane tube aorta had a single visceral while four windkessel components mimicked resistance compliance of the brachiocephalic, renal and sub-mesenteric, pulmonary, and systemic circulation. Twelve flow probes were placed in the circuit to measure pressures and flows with the IABP on and off. With the balloon off, the meantime to reach the steady state was 48 ± 16 s; with the balloon on, this figure was 178 ± 20 s. The stability of pressure and flow signals was obtained after 72 ± 11 min. The number of cycles of stability of the system was 93 [86-103]. Measurements were reliable either with samples of 10 or 20 beats. Bland Altman method demonstrated the reliability of measurements. Finally, all measurements were comparable to published in vivo data. The presented mock circulation was reliable and gave values with high accuracy both at baseline and during mechanical assistance. This system allows evaluation of the mesenteric flow during IABP, under different clinical/hemodynamic conditions. Nonetheless, its translational potential needs to be further evaluated.

The Characteristics and Clinical Outcomes of Rotational Atherectomy under Intra-Aortic Balloon Counterpulsation Assistance for Complex and Very High-Risk Coronary Interventions in Contemporary Practice: An Eight-Year Experience from a Tertiary Center.

The use of Complex and High-risk Coronary Interventions (CHIPs) has increased in recent years. Both rotational atherectomy (RA) and hemodynamic support are important parts of CHIPs. This study aimed to retrospectively investigate the procedure results and clinical outcomes of intra-aortic balloon pump (IABP)-assisted RA in the contemporary drug-eluting stent era. All consecutive patients who received RA under in-procedure IABP assistance from April 2010 to March 2018 were analyzed retrospectively. A total of 63 patients (77.7 ± 10.1 years, 69.8% male) were recruited, of whom 51 underwent RA with primary IABP assistance and 12 underwent bailout IABP. RA could be completed in 61 (96.8%) of the patients. Overall, vessel perforation, profound in-procedure shock, and ventricular arrhythmia occurred in 1.6%, 4.8% and 3.2% of the patients, respectively. The in-hospital, 30-day and 90-day major adverse cardiac event (MACE) rates were 22.2%, 27.4% and 36.1%, respectively, mostly driven by mortality. The MACE rates were significantly higher in the bail-out group in the hospital (50.0% vs. 15.7%, p = 0.018) at 30 days (58.3% vs. 20.0%, p = 0.013) and 90 days (66.7% vs. 28.6%, p = 0.020). Bail-out IABP was associated with increased MACEs, implying that the use of IABP should be implemented at the beginning of RA if a complex procedure is anticipated.

Intra-aortic balloon counterpulsation timing: A new numerical model for programming and training in the clinical environment.

Background and ObjectiveThe intra-aortic balloon pump (IABP) is the most widely available device for short-term mechanical circulatory support, often used to wean off cardiopulmonary bypass or combined with extra-corporeal membrane oxygenation support or as a bridge to a left ventricular assist device. Although based on a relatively simple principle, its complex interaction with the cardiovascular system remains challenging and open to debate. The aim of this work was focused on the development of a new numerical model of IABP. MethodsThe new model was implemented in CARDIOSIM©, which is a modular software simulator of the cardiovascular system used in research and e-learning environment. The IABP is inserted into the systemic bed divided in aortic, thoracic and two abdominal tracts modelled with resistances, inertances and compliances. The effect induced by the balloon is reproduced in each tract of the aorta by the presence of compliances connected to PIABP generator and resistances. PIABP generator reproduces the balloon pressure with the option to change IABP timing. We have used literature data to validate the potential of this new numerical model. ResultsThe results have shown that our simulations reproduced the typical effects induced during IABP assistance. We have also simulated the effects induced by the device on the hemodynamic variables when the IABP ratio was set to 1:1, 1:2, 1:4 and 1:8. The outcome of these simulations is in accordance with literature data measured in the clinical environment. ConclusionsThe new IABP module is easy to manage and can be used as a training tool in a clinical setting. Although based on literature data, the outcome of the simulations is encouraging. Additional work is ongoing with a view to further validate its features. The configuration of CARDIOSIM© presented in this work allows the simulation of the effects induced by mechanical ventilatory assistance. This facility may have significant importance in the management of patients affected by COVID-19 when they require mechanical circulatory support devices.

A CFD investigation of intra-aortic balloon pump assist ratio effects on aortic hemodynamics

Intra-aortic balloon pump (IABP) is a mechanical circulatory support approach used in case of several cardiac diseases and a challenge of IABP therapy is the weaning process accomplished by decreasing the assist ratio. However, the impact of weaning on aortic hemodynamics on organs perfusions is not well known.Aim of this study was to evaluate and compare the global effects of IABP assistance frequencies on hemodynamics and perfusions in a patient-specific geometry by means of the computational fluid dynamics (CFD). A 3D aorta model was obtained from CT images using segmentation and reverse engineering techniques. The balloon was modeled and positioned in the descending aorta as in clinical practice and its inflation/deflation behavior was realized with a parametric study. Four assist ratios have been investigated: full assistance (1:1), partial assistances (1:2 and 1:3) and weak assistance (1:4). To perform the comparison, same boundary conditions were applied.Our results highlighted that the presence of balloon in aorta modifies significantly its hemodynamics and that the four assist ratios generate different perfusions in the human districts. Data suggested also that the biggest difference occurs between 1:2 and 1:3 frequencies and that 1:4 ratio is more suitable for the weaning of counterpulsation treatment than the 1:3 ratio.This first CFD analysis of IABP weaning increases information and knowledge on hemodynamics and organs perfusions.

Modified double patch repair with infarct exclusion technique for ventricular septal perforation: a case study

BackgroundVentricular septal perforation (VSP) after acute myocardial infarction (AMI) is accompanied by the worsening of rapid hemodynamics, resulting in a poor prognosis. In our department, infarct lesions are preoperatively detected with electrocardiogram (ECG)-synchronized contrast computed tomography, and the scope of approach and exclusion is determined. Furthermore, to effectively prevent a residual shunt, modified double patch repair and infarct exclusion techniques were used in combination to preserve left ventricular (LV) function. This method is reported because it considers both techniques as a surgical procedure that can be accomplished relatively easily and simultaneously.Case presentationWe targeted two consecutive VSP patients who underwent this procedure. It took an average of 1 day from the onset of VSP to surgery. We performed double patch and infarct exclusion for VSP using bovine pericardium via an LV incision. Two patches were marked with a skin pen to anastomose eight mattresses equally. In addition, a one piece-coupled patch was made for infarct exclusion. The two patients were extubated on the day after surgery and intra-aortic balloon pump assistance was also withdrawn. Without perioperative complications, they could leave the intensive care unit after 6.5 days on average. Early postoperative ECG and magnetic resonance angiography showed good LV wall contraction, except at the infarcted area, with no evidence of a residual shunt.ConclusionThe modified double patch repair with infarct exclusion technique is more effective for preventing a residual shunt and maintaining postoperative cardiac function than either of the techniques alone.

Comparative in vivo analysis of the role of the adventitia and the endothelium on arterial mechanical function: relevance for aortic counterpulsation.

The comparative effect of the intimal and adventitial layers on arterial biomechanics control, in basal and altered conditions, remains to be elucidated. This study aimed (1) to characterize the arterial conduit (CF) and buffering (distensibility) function of the iliac arteries in in vivo animals, in which the intimal and adventitial layers were removed; (2) to determine the effects of intra-aortic ballon pumping (IABP) on simultaneously de-adventitialized (DA) and de-endothelialized (DE) iliac arteries before and after induced heart failure. Pressure and diameter signals were measured in the iliac arteries of sheep (n = 7) in which the adventitial and intima layer were removed. Intra-aortic balloon pump (IABP) assistance was used in a control state and after heart failure induction. Both DE and DA determined significant changes in arterial diameter, distensibility and CF. Changes were higher after DA than after DE in terms of distensibility and CF (p<0.05). DA followed by DE (DA + DE) showed significant increases in arterial diameter and CF, accompanied by a decrease in distensibility (p<0.05) with respect to intact arteries. Heart failure induction caused significant hemodynamic changes without modifying the already impaired local biomechanical parameters. Nonsignificant improvements in the biomechanical parameters of DA + DE iliac arteries were observed during IABP before and after heart failure induction. Biomechanical changes caused by DA of iliac arteries were more important than those observed after DE. The DA + DE arteries showed significant differences with respect to intact arteries and with DA or DE arteries. IABP-related effects on arterial mechanics were absent in DA + DE arteries.

Is visceral flow during intra-aortic balloon pumping size or volume dependent?

We evaluated the influence of intra-aortic balloon size and volume on mesenteric and renal flows. Thirty healthy swine underwent 120-minute ligation of the left anterior descending coronary artery followed by 6 hours of reperfusion. Then, they were randomly assigned to the following five groups of animals, with six animals in each group: no intra-aortic balloon pump (IABP), a short 35-mL IABP, a short 40-mL IABP, a long 35-mL IABP and a long 40-mL IABP. Superior mesenteric artery (SMA) and renal flows were measured at baseline (t0), at 2-hour ischemia (t1) and every hour thereafter until 6 hours of reperfusion (from tR1 to tR6). SMA flows increased significantly at tR1 only in the two short IABP groups (p<0.001) and balloon volume did not appear to affect flows which, at any experimental time-point, were comparable using 35 mL or 40 mL balloons (p>0.05). Renal flows appeared to be influenced by balloon length, but not by volume. Indeed, flows in the renal arteries rose during IABP treatment; the increase was significantly higher in the short balloon groups and throughout the whole reperfusion (all, p<0.001). Changes in visceral perfusion during IABP assistance were significantly related to balloon length, but not to its volume. This could be relevant for the evolution of balloon engineering design in order to reduce the incidence of mesenteric ischemia following IABP. Further research is necessary to confirm these findings.

Expanding minimally invasive innovation to complex mitral reoperations.

The increasing familiarity with minimally invasive mitral surgical approaches have enabled the technical progression from sternotomy to mini-sternotomy, from direct vision mini-thoracotomy to video-assisted mini-thoracotomy, and now to a resurgence of robotic-assisted mitral surgery [1]. Maintaining quality outcomes through this step-wise progression is essential. Perfusion and cannula enhancements facilitating non-sternotomy mitral access can be applied safely using conventional cross-clamping and endoballoon aortic occlusion, even in reoperations [2]. Similarly, good outcomes to isolated mitral reoperations can be accomplished via right thoracotomy on the normothermic centrally cannulated beating heart. At our institution, this has become the favoured method to address these complex cases, with the majority of patients extubated immediately postoperatively without blood products. In this issue of the Multimedia Manual of Cardio-Thoracic Surgery, Botta et al. [3] from Milano bravely outline their approach to complex reoperations using a minimally invasive approach on the unclamped aorta. Their experience with 40 patients between 2008 and 2014 showcases their use of moderate hypothermic ventricular fibrillation including an elegantly performed video case example on a 75-year-old patient requiring a fourth time redo operation. Though the average ejection fraction was 50%, their patients were admittedly at high risk with one-quarter having more than one prior cardiac operation, one-third in renal failure and half having undergone prior surgical revascularization. The authors believe that fibrillatory arrest performed between 27 and 28° centigrade for an average time of 95 min with transient flow reductions enabled better valve exposure with minimal dis section while still achieving adequate myocardial protection. However, in this series of complex patients, 10% (4/40) had low output states requiring intra-aortic balloon pump assistance, 7.5% (3/40) had a cerebrovascular event, the majority were transfused and there was a 10% (4/40) in-hospital operative mortality. Whether centrally or peripherally cannulated, the use of fibrilla tory arrest under moderate hypothermia for redo mitral operations remains popular in selected experienced centres. As demon strated by the authors, this may indeed be a useful tool in certain cases where surgical courage is called upon to navigate otherwise very complex patients through a mitral reoperation. While fibrillatory arrest can be useful, history recounts that even with hypothermia, the ventricular subendocardium may be suboptimally protected when the perfusion pressure is reduced to the levels used in clinical cardiac surgery [4]. The reduced wall stress and myocardial demands from an empty beating heart or arrested heart may continue to have a role in these complex operations. Moreover, the use of CT angiographic mapping preoperatively, as done by the authors, is essential to avoid complications of femoral cannulation in mitral reoperations [1, 5]. Botta et al. have provided us with a progressive approach to add to the armamentarium of high-risk mitral reoperations. However, as programmes attempt these cases for the first time, the use of outcome-focused patient-specific alternate cannulation and perfusion strategies should still be considered. Attention to safety and quality should always be kept at the forefront as we expand the application of technical innovation to a broader array of patients.

Anaphylactic Shock Decreases Cerebral Blood Flow More Than What Would Be Expected From Severe Arterial Hypotension

To the Editor In a recent issue of Shock (1), a very important paper was published with the title: “Anaphylactic Shock Decreases Cerebral Blood Flow More Than What Would Be Expected From Severe Arterial Hypotension.” The authors of this article concluded that, in anaphylactic shock, severe impairment of the cerebral blood flow takes place, which could not be explained by the level of arterial hypotension. In their experiments with rat model of anaphylaxis, the tissue oxygen partial pressure decreased very rapidly, as early as 1 min following the onset of anaphylaxis, and this was attributed to the early and direct action of anaphylactic mediators on cerebral vessels. Indeed, mast cell mediators such as histamine, chymase, and leukotrienes can induce cerebral artery spasm (2), and platelet-activating factor can reduce cerebral blood flow (3), leading to postischemic hypoperfusion. Therefore, cerebral ischemia and brain injury following anaphylactic shock could be due to direct action of anaphylactic mediators on the cerebral arterial system and not due to arterial hypotension. The above came to support our view on pathophysiology of anaphylactic shock that systemic vasodilatation and plasma and volume loss due to vascular permeability, reduced venous return, reduced cardiac output, and coronary hypoperfusion are not the sole primary cause of tissue damage. Experimental and clinical evidence has shown that, in anaphylactic shock, the coronary arteries could be the primary target of anaphylaxis (4), resulting in the development of Kounis anaphylaxis–associated coronary syndrome (5). In an experiment with ovalbumin-sensitized guinea pigs, which took place more than 20 years ago (6), it was concluded that the registered anaphylactic damage was not due to peripheral vasodilatation, and this can be definitely excluded. This was based on the finding that within 3 min after antigen administration, the left ventricular end-diastolic pressure and arterial blood pressure increased, indicating pump failure. Contemporarily, electrocardiographic recordings uniformly showed signs of acute myocardial ischemia. The blood pressure started declining steadily after 4 min. Today, Dr Stephan Felix (6), the author who performed the above experiments, still believes that, in anaphylactic shock, tissue ischemia is due to disturbances of vasomotion of the coronaries (either coronary vasospasm or disturbances of the microcirculation). However, he cannot exclude fluid extravasation (personal communication, email, November 26, 2012). Other experiments (7), with isolated guinea pig hearts undergoing anaphylaxis following intra-aortic injection of antigen, have shown a prompt and prolonged decrease in coronary blood flow, an abrupt heart rate increase reaching the peak within 2 min, and a transient increase in ventricular contractile force. It has been shown also (8) that anaphylactic cardiac damage is dissociated temporarily into two sets of events: an initial primary coronary reaction caused by intracardiac release of histamine and a subsequent cardiovascular reaction secondary to systemic release of mediators. There are, currently, patients with anaphylactic cardiac shock who did not respond to intravenous fluid administration and antiallergic therapy but required coronary event treatment protocol. In a patient (9) who was stung by multiple wasps and developed type I variant of Kounis syndrome with anaphylactic shock and myocardial ischemia, treatment with 2 L of normal saline, adrenaline, hydrocortisone, and antihistamines did not have any immediate effect, and the patient recovered in a later stage with vasopressors and myocardial infarction protocol treatment. In an atopic female nurse (10) with previous atopic eczema, asthma, and allergy to milk protein, who suffered an anaphylactic reaction, hemodynamic status was unresponsive to intravenous administration of fluids such as Ringer’s acetate and antiallergic treatment with adrenaline and corticosteroids, but the patient recovered with myocardial infarction protocol treatment. It was commented that hemodynamic disturbance was most probably due to myocardial stunning leading to reduced cardiac output rather than due to fluid extravasation. In another patient with hymenoptera sting–induced anaphylactic shock (11), urgent coronary angiography revealed acute coronary thrombosis, and the patient recovered with intra-aortic balloon pump assistance and myocardial infarction treatment. Differentiating global hypoperfusion from primary tissue suppression due to mast cell mediator action on systemic arterial vasculature seems to be challenging. Combined tissue suppression from arterial involvement and peripheral vasodilatation, perhaps, occur simultaneously. Although the mechanisms of anaphylactic shock still remain to be elucidated, the above effects resemble those during endotoxin administration and postischemic hypoperfusion (3). In this aspect, the experiments of Davidson et al (1) help to understand the pathophysiology of anaphylactic shock, but further studies are needed to determine the importance of mediators of anaphylaxis in cerebral and myocardial pathobiology. Nicholas Kounis George N. Kounis George D. Soufras Andreas Mazarakis Department of Medical Sciences Patras Highest Institute of Education and Technology Patras, Grecce

Hybrid Model Analysis of Intra‐Aortic Balloon Pump Performance as a Function of Ventricular and Circulatory Parameters

We investigated the effects of the intra-aortic balloon pump (IABP) on endocardial viability ratio (EVR), cardiac output (CO), end-systolic (V(es)) and end-diastolic (V(ed)) ventricular volumes, total coronary blood flow (TCBF), and ventricular energetics (external work [EW], pressure-volume area [PVA]) under different ventricular (E(max) and diastolic stiffness) and circulatory (arterial compliance) parameters. We derived a hybrid model from a computational model, which is based on merging computational and hydraulic submodels. The lumped parameter computational submodel consists of left and right hearts and systemic, pulmonary, and coronary circulations. The hydraulic submodel includes part of the systemic arterial circulation, essentially a silicone rubber tube representing the aorta, which contains a 40-mL IAB. EVR, CO, V(es), and V(ed), TCBF and ventricular energetics (EW, PVA) were analyzed against the ranges of left ventricular E(max) (0.3-0.5-1 mm Hg/cm(3)) and diastolic stiffness V(stiffness) (≈0.08 and ≈0.3 mm Hg/cm(3), obtained by changing diastolic stiffness constant) and systemic arterial compliance (1.8-2.5 cm(3)/mm Hg). All experiments were performed comparing the selected variables before and during IABP assistance. Increasing E(maxl) from 0.5 to 2 mm Hg/cm(3) resulted in IABP assistance producing lower percentage changes in the selected variables. The changes in ventricular diastolic stiffness strongly influence both absolute value of EVR and its variations during IABP (71 and 65% for lower and higher arterial compliance, respectively). V(ed) and V(es) changes are rather small but higher for lower E(max) and higher V(stiffness). Lower E(max) and higher V(stiffness) resulted in higher TCBF and CO during IABP assistance (∼35 and 10%, respectively). The use of this hybrid model allows for testing real devices in realistic, stable, and repeatable circulatory conditions. Specifically, the presented results show that IABP performance is dependent, at least in part, on left ventricular filling, ejection characteristics, and arterial compliance. It is possible in this way to simulate patient-specific conditions and predict the IABP performance at different values of the circulatory or ventricular parameters. Further work is required to study the conditions for heart recovery modeling, baroreceptor controls, and physiological feedbacks.

Mechanical Assistance by Intra‐Aortic Balloon Pump Counterpulsation During Reperfusion Increases Coronary Blood Flow and Mitigates the No‐Reflow Phenomenon: An Experimental Study

The effects of the intra-aortic balloon pump (IABP) counterpulsation on the extent of myocardial infarction (MI), the no-reflow phenomenon (NRP), and coronary blood flow (CBF) during reperfusion in an ischemia-reperfusion experimental model have not been clarified. Eleven pigs underwent occlusion of the mid left anterior descending coronary artery for 1 h, followed by reperfusion for 2 h. CBF, distal to the occlusion site, was measured. In six experiments, IABP support began 10 min before, and continued throughout reperfusion (IABP Group). Five pigs without IABP support served as controls. At the end of each experiment, the myocardial area at risk (MAR) of infarction and the extent of MI and NRP were measured. Hemodynamic measurements at baseline and during coronary occlusion were similar in both groups. During reperfusion, systolic aortic blood pressure was significantly lower in the IABP Group than in controls. In the IABP Group, CBF reached a peak at 5 min of reperfusion, gradually decreased, but remained higher than at baseline, and significantly higher than in controls throughout the 2 h of reperfusion. In controls, CBF increased significantly above baseline immediately after the onset of reperfusion, then returned to baseline within 90 min. The extent of NRP (37 ± 25% vs. 68 ± 17%, P = 0.047) and MI (39 ± 23% vs. 67 ± 13%, P = 0.036), both expressed as percentage of MAR, was significantly less in the IABP group than in controls. After prolonged myocardial ischemia, IABP assistance started just 10 min before and throughout reperfusion increased CBF and limited infarct size and extent of NRP.

Wave energy patterns of counterpulsation: A novel approach with wave intensity analysis

In counterpulsation, diastolic augmentation increases coronary blood flow and systolic unloading reduces left ventricular afterload. We present a new approach with wave intensity analysis to revisit and explain counterpulsation principles. In an acute porcine model, a standard intra-aortic balloon pump was placed in descending aorta in 4 pigs. We measured pressure and velocity with probes in left anterior descending artery and aorta during and without intra-aortic balloon pump assistance. Wave intensities of aortic and left coronary waves were derived from pressure and flow measurements with synchronization correction. We identified predominating waves in counterpulsation. In the aorta, during diastolic augmentation, intra-aortic balloon inflation generated a backward compression wave, with a "pushing" effect toward the aortic root that translated to a forward compression wave into coronary circulation. During systolic unloading, intra-aortic balloon pump deflation generated a backward expansion wave that "sucked" blood from left coronary bed into the aorta. While this backward expansion wave translated to reduced left ventricular afterload, the "sucking" effect resulted in left coronary blood steal, as demonstrated by a forward expansion wave in left anterior descending coronary flow. The waves were sensitive to inflation and deflation timing, with just 25 ms delay from standard deflation timing leading to weaker forward expansion wave and less coronary regurgitation. Intra-aortic balloon pumps generate backward-traveling waves that predominantly drive aortic and coronary blood flow during counterpulsation. Wave intensity analysis of arterial circulations may provide a mechanism to explain diastolic augmentation and systolic unloading of intra-aortic balloon pump counterpulsation.

Hemodynamic and Metabolic Effects of Para- versus Intraaortic Counterpulsatile Circulation Supports

Despite the success of intraaortic balloon counterpulsation, data on physiologic indices and optimal inflation/deflation timing control of chronic counterpulsation devices are unclear. This study explored the acute hemodynamic and metabolic efficacy of a novel 40-ml stroke volume paraaortic blood pump (PABP) versus a standard intraaortic balloon pump (IABP). Acute porcine model was used with eight pigs randomly divided into PABP (n = 4) and IABP (n = 4) groups. Hemodynamic and metabolic measurements were obtained with and without mechanical assistance. In one pig, the inflation/deflation control was adjusted to different settings, with corresponding performance indices measured. The PABP significantly improved classical counterpulsation indices (p ≤ 0.05) and achieved an average beneficial effect on these indices 1.5-3.5 times greater than that of the IABP. Classical metabolic indices (tension time index and endocardial viability ratio [EVR]), and indices new to chronic counterpulsation research (coronary perfusion, left ventricular stroke work (SW), and a newly derived EVR) were also used in assessment. Both IABP assistance and PABP assistance improved these physiologic indices, with a trend toward PABP superiority in reducing left ventricular SW (p = 0.08). An optimal PABP deflation timing occurs during systole (25 milliseconds after the R-wave) and can minimize coronary regurgitation.

Cardiac output by thermodilution and the MostCare system in patients on intra-aortic balloon pump

The intra-aortic balloon pump (IABP) is a device used to help the heart pump. During the IABP assistance, significant changes in arterial pressure waveform occur. The so-called pulse contour methods (PCMs) use proper algorithms to analyse the arterial pressure waveform and obtain the cardiac output (CO) [1]. As a consequence, changes in pressure waveform in patients on IABP may affect the reliability of different PCMs. The aim of this study was to investigated the reliability of a new PCM, the MostCare powered by the pressure recording analytical method (PRAM) (Vytech Health, Laboratoires Pharmaceutiques Vygon, Ecouen, France), by comparing its CO values (PRAM-CO) with those determined by bolus thermodilution (ThD-CO) during aortic counterpulsation.