Mechanical Cardiovascular Support Research Articles

Use of cardiopulmonary bypass machine in intensive care unit as a short term mechanical circulatory support for recovery of cardiac function.

Extracorporeal Membrane Oxygenation (ECMO) is used as a bridge to recovery of cardiac function following completion of congenital cardiac surgeries where there is failure to wean from cardiopulmonary bypass (CPB) or severe low cardiac output states in the post operative periods. Although ECMO is a well-established form of mechanical circulatory support, the associated cost can be a huge financial burden on families. We are an ECMO center and use the same in post operative congenital cardiac surgeries for mechanical cardiovascular support if needed. However, a significant proportion of the children, whom we operate, are funded by government aides. The resources are limited in such circumstances. If needed, we use the same CPB circuit and cannulae used in the Operating Room (OR) and support them at a significantly lower cost compared to ECMO. We report our experience of using conventional CPB machine as a short-term bridge to recovery of cardiac function in Intensive Care Unit where there was limitation of funds. Essentially same CPB circuit with roller pump is retained, by omitting cardiotomy suckers. We use D901 Lilliput 1 Oxygenator (Sorin, Italy) for children <5kg and D902 Lilliput 2 (Sorin, Italy) Oxygenator for children >5Kg. We supported nine patients on CPB between March 2019 and December 2021. During this time, 1392 congenital cardiac surgeries were performed. We could wean off three patients (33.3%) and discharge two patients (22.2%). Our support time ranged from 21h to 60h with a median of 48h. Beyond 48h of support, we experienced several CPB induced complications in our cohort. In resource-limited settings, conventional CPB machines can be used for short-term cardiac support. Although results may not be comparable to using ECMO, some patients can be definitely salvaged, who would otherwise die in the absence of institution of mechanical circulatory support.

COVID-19 after heart transplantation: experiences from aGerman transplantation center

HintergrundDie durch SARS-CoV‑2 (Severe acute respiratory syndrome coronavirus type 2) verursachte Erkrankung gilt bei immunsupprimierten Patienten als besonders gefährlich. Patienten nach einer Herztransplantation zählen zu den Gruppen mit langjähriger, meist 3‑facher Immunsuppression. In der Literatur werden schwerwiegende klinische Verläufe beschrieben.Ziel der Arbeit (Fragestellung)In dieser Arbeit wird über unsere Erfahrungen mit COVID-19 (coronavirus disease 2019) bei herztransplantierten Patienten an einem deutschen Transplantationszentrum longitudinal über die bisherigen Pandemiewellen berichtet und es erfolgt eine Einordnung dieser in publizierte Erfahrungen anderer Zentren.Material und MethodenAlle adulten herztransplantierten Patienten unseres Zentrums, bei denen nach der Herztransplantation eine SARS-CoV-2-Infektion nachgewiesen wurde (n = 12), wurden eingeschlossen und retrospektiv analysiert.ErgebnisseDas Durchschnittsalter betrug 61,5 (49 bis 63) Jahre; die Mehrheit der Patienten war männlich (83 %). Die häufigsten Komorbiditäten waren Diabetes (42 %), arterielle Hypertonie (43 %) sowie chronische Niereninsuffizienz (67 %). Bei 50 % erfolgte bei Krankenhausaufnahme eine passive Immunisierung (Rekonvaleszenzplasma/monoklonale Antikörper). Eine Sauerstoffgabe war bei 33 % der Patienten notwendig; nur ein Patient erhielt eine nichtinvasive Ventilation (8 %). Kein Patient benötigte eine invasive Beatmung oder eine mechanische Herz-Kreislauf-Unterstützung (ECMO). Es fanden sich keine neuen kardiovaskulären oder thrombembolischen Ereignisse.ZusammenfassungIn dieser Kohorte konnten wir longitudinal keine schweren Verläufe oder eine erhöhte Mortalität von COVID-19 in herztransplantierten Patienten detektieren. Prospektive Studien sind notwendig, um in Zukunft bessere Prognoseabschätzungen bei COVID-19 in (herz-)transplantierten Patienten treffen zu können.

Conventional cardiac surgery in patients with end-stage coronary artery disease: yesterday and today.

Surgical therapy of combined coronary artery disease (CAD) and heart failure, also referred to as end-stage CAD, has evolved throughout the years and patients are currently being offered traditional coronary artery bypass grafting (CABG), with or without surgical ventricle restoration (SVR), interventions for ischemic mitral valve regurgitation, heart transplantation or implantation of mechanical cardiovascular support systems. Among surgical methods, operative myocardial revascularization (with or without ventricle restoration) is still playing an important role, aiming at restoration of proper myocardial perfusion, especially if heart muscle viability is present. Facing the donor shortage, CABG may constitute a valuable alternative to transplantation in selected patients. In individuals considered not suitable for surgical revascularization, implantation of mechanical circulatory support (MCS) not only appears as a salvage procedure, but also allows for reevaluation of future therapy directions. This article aims at providing an overview of evolving and current surgical practices in patients with end-stage CAD.

Miocarditis en Pediatría

Myocarditis is an inflammatory disease of the heart muscle unrelated to valvular abnormalities and ischaemic disease. The prevalence and incidence are unknown since it is presented sub-acutely or with non-specific initial symptoms. Its pathophysiology consists of three phases: acute <3 days–myocardial damage mediated by direct action a virus), sub-acute (4-14 days–the myocardial damage is due to a dysregulation of an autoimmune host response), and chronic (>15 days - insufficient viral clearance and perpetuation of the inflammatory process, which leads to cardiac remodelling and heart failure). Parvovirus B19 and human herpesvirus 6 have been described as the most common aetiological agents. The clinical signs include, chest pain, arrhythmias, and in infants (lethargy, tachypnoea, mild shortness of breath, etc.) It can start with a viral prodrome, ventricular dysfunction, or sudden death. There are four possibilities of clinical presentation: asymptomatic, acute myocarditis, fulminant or dilated chronic cardiomyopathy. The electrocardiogram detects between 93%-100% of abnormalities. Cardiovascular nuclear magnetic resonance with gadolinium is the most used, mainly in endomyocardial biopsy. Treatment is based on the haemodynamic monitoring of the patient, the evaluation of the need for diuretics, angiotensin converting enzyme inhibitors, non-selective beta-blockers, inotropic support, anti-arrhythmic drugs or, in severe cases, and the need for mechanical cardiovascular support. The use of immunoglobulin has been evaluated, and there is controversy over the use of immunosuppressives and antivirals. The prognosis is variable and depends on factors inherent to the environment and the host. An updated review of the literature is presented.

Novel combination of impella and extra corporeal membrane oxygenation as a bridge to full recovery in fulminant myocarditis.

A 31-year-old male was transferred to our hospital with severe heart failure due to viral myocarditis. He progressed to multiorgan failure requiring intubation and maximal doses of multiple vasopressors. Circulatory support was provided with an Impella device as a bridge to an extracorporeal membrane oxygenation (ECMO) system. On full mechanical cardiovascular support, the patient's hemodynamic status improved and ECMO and Impella were explanted after 48 hours. Three days later, he was extubated and continued on to a full recovery. There are no specific therapies for fulminant myocarditis but first-line treatment is supportive care. ECMO is commonly used in patients with severe heart failure. In severe systolic dysfunction, left ventricular decompression is required to reduce myocardial wall stress, decrease myocardial oxygen requirements, and enhance the chances of recovery. The Impella, an active support system, is less invasive than classical decompressive techniques and is associated with lower requirements for blood products with fewer thromboembolic complications. This is the only case reported of the contemporary use of Impella and ECMO as a bridge to full recovery in an adult with myocarditis. It also presents a novel use of the Impella device in decompressing the left ventricle of an adult patient on ECMO.

Treatment of Serious Calcium Channel Blocker Overdose With Levosimendan, a Calcium Sensitizer

Calcium channel blocker (CCB) overdose is often lethal. Conventional medical treatment includes i.v. calcium, high doses of catecholamines, insulin, and glucagon. A new inotropic drug, levosimendan, should be considered in severe CCB poisoning. Levosimendan's pharmacologic features differ from other inotropic drugs. It is a calcium sensitizer and improves contraction without increasing intracytosolic calcium concentration. We describe two patients with serious CCB overdose. Despite intensive medical and mechanical cardiovascular support, both patients remained in shock. Hemodynamics gradually improved after administration of levosimendan.

Extracorporeal membrane oxygenation for postcardiotomy mechanical cardiovascular support in children with congenital heart disease

Extracorporeal membrane oxygenation (ECMO) is increasingly used to support postcardiotomy cardiorespiratory failure in children with congenital heart disease. We report on survival outcomes and factors associated with survival for postcardiotomy ECMO patients.

Change in design of intra‐aortic balloon catheter

We would like to report an incident which led us to mistakenly believe that the gas lumen insert from an intra-aortic balloon catheter (IABC) had broken in situ. A patient was admitted to the Critical Care Unit with severe cardiogenic shock. Mechanical cardiovascular support was required and an 8 Fr Co-Lumen 40 cc Intra-Aortic Balloon Catheter (Datascope Corp., Mahwah, NJ) was inserted. Once the catheter had been correctly placed, the long plastic gas lumen insert was removed and the tip was inspected to look for the two black stripes that mark the distal end (Fig. 3). These markings are provided to allow confirmation that the entire gas lumen insert has been removed. The black stripes were, however, absent. In the belief that a piece of the insert had broken off and remained in situ, we removed the IABC and inserted a second catheter. On this occasion the markings indicating complete removal of the insert were present and intra-aortic balloon counterpulsation was initiated with good effect. Subsequent inspection revealed that both inserts were of the same length. The markings on the Profile design (left) are clearly visible. The Fidelity insert (right) has no markings. Following further investigation we have established that there were two types of Datascope 8 Fr catheter available on our unit. The first variant (Profile 8 Fr) had been in use for several years and the instruction booklet supplied clearly states ‘to verify that the entire gas lumen insert has been removed look for the two black stripes at the end of the insert’. This had become our normal practice. A new catheter had been subsequently introduced (Fidelity 8 Fr) but the gas lumen insert lacks such marking at the tip. On this occasion we had used the Fidelity catheter for the initial insertion and removed it in error as we were unaware that the markings were no longer provided. The medical and nursing staff were unaware of the change in the design of the IABC gas lumen insert. In addition, the relevant section of the instruction booklet provided with the ‘Fidelity’ catheter (paragraph C4) does not mention that the markings are no longer present. As a result we removed, and wasted, the initial catheter and subjected the patient to the additional risk of a second placement. We would suggest that clinicians check carefully whether or not they should expect to find markings on the gas lumen insert prior to use.

VALIDATION OF CFD RESULTS USED FOR HEMOLYSIS PREDICTION

Computational fluid dynamics (CFD) analyses have played important roles in developing heart valves, blood pumps, and other mechanical cardiovascular support devices. Increasingly, investigators are attempting to predict hemolysis directly from their CFD simulations of the devices they are developing. This requires a hemolysis prediction model usually derived from a power-law equation of shear stress and exposure time, and a shear field estimate based on various assumptions underlying the CFD analyses. However, most of these investigators either have no experimental data at all to validate their CFD simulations or only have global performance measurements for comparison. Our experience with one of our blood pumps has shown that for the same pump system, slight changes of the meshing parameters will result in pressure rise predictions that are all confirmed by experimental performance measurements. However, the hemolysis prediction varies by 36%. With another blood pump we developed, two simulations using the same meshing parameters but two different turbulence models again accurately predicted the pressure rise, but the hemolysis prediction varied by an order of magnitude. With either pump, different simulations resulted in different pressure contours in local regions, even though gross performance was the same. Our results indicate that it is inadequate to validate CFD simulations with pressure-flow-power data. It is necessary to validate CFD simulations with detailed flow field measurements, before a hemolysis prediction can be made with useful accuracy.

Prognostic Significance of Inverted T Waves in Patients With Acute Pulmonary Embolism

The significance of inverted T waves remains unclear in patients with acute pulmonary embolism (PE). The relationship of the number of leads with inverted T waves to the severity of PE in 40 patients with acute PE was studied. Patients were classified into 3 groups according to the number of leads with inverted T waves on the admission electrocardiogram (ECG): 15 patients, <or=3 leads (group L); 12 patients, 4-6 leads (group M); and 13 patients, >or=7 leads (group H). In groups L, M and H, the rates of right ventricular dysfunction on echocardiography were 47%, 92% and 100% (p<0.01), respectively, and the rates of in-hospital complicated events (including death or the need for catecholamine support, cardiopulmonary resuscitation or mechanical cardiovascular support because of hemodynamic instability) were 0%, 8% and 46% (p=0.004), respectively. On multivariate analysis, arterial hypotension at presentation (odds ratio (OR) 8.96, p=0.049) and inverted T waves in >or=7 leads on the admission ECG (OR 16.8, p=0.037) were the only independent predictors of in-hospital complicated events. The number of leads with inverted T waves may be a useful and simple marker of increased risk for early complications in patients with acute PE.

Utility of B-type natriuretic peptide in predicting the level of peri- and postoperative cardiovascular support required after coronary artery bypass grafting*

To determine whether preoperative plasma levels of B-type natriuretic peptide would allow for the prediction of perioperative and early postoperative cardiovascular support requirements and hospital bed usage after coronary artery surgery. A prospective observational cohort study. A tertiary referral cardiothoracic unit in Scotland. Forty-six consecutive patients undergoing coronary artery surgery. None. Demographics, clinical details, preoperative and postoperative B-type natriuretic peptide levels, type of surgery, postoperative complications, postoperative cardiac troponin I levels, and duration of stay were collected. Preoperative plasma levels of B-type natriuretic peptide are significantly higher in patients who require perioperative inotropic or mechanical cardiovascular support, compared with those who do not. They are also higher in those who require postoperative inotropic or mechanical cardiovascular support, compared with those who do not. B-type natriuretic peptide levels are higher in those who require increased intensive care unit stay but not a prolonged hospital stay. Preoperative plasma levels of B-type natriuretic peptide levels may be useful in predicting the need for increased peri and postoperative cardiovascular support and a more prolonged stays in intensive care following coronary artery surgery.

High lactate predicts the failure of intraaortic balloon pumping after cardiac surgery

Background. Despite the use of intraaortic balloon pump (IABP) support in complex cardiac surgical patients, morbidity and mortality rates are high. More advanced mechanical cardiovascular support should be considered in those patients who are highly likely to die despite IABP support. We sought to identify early, readily available prognostic markers for patients receiving IABP support.Methods. A retrospective analysis was performed on 39 patients requiring IABP support following cardiac surgery for more than 2 years. The accuracy and predictive ability of multiple potential markers of mortality were statistically assessed.Results. Sixty-seven percent of the patients were successfully weaned from IABP support and 46% survived to hospital discharge. Serious complications occurred in 13% of patients. Serum lactate more than 10 mmol/L in the first 8 hours of IABP support predicted a 100% mortality. Base deficit more than 10 mmol/L, mean arterial pressure less than 60 mm Hg, urine output less than 30 mls/h for 2 hours, and dose of epinephrine or norepinephrine more than 10 μg/min were other highly predictive prognostic markers.Conclusions. Morbidity and mortality rates remain high despite IABP support following cardiac surgery. Mortality can be predicted by the presence of elevated serum lactate, elevated base deficit, hypotension, oliguria and large vasopressor doses, any of which should prompt appropriate consideration as to other mechanical cardiovascular support.

The present state of heart transplantation

After more than 25 years, including long periods of scepticism, heart transplantation, with the introduction of several fundamental innovations, has become a routine clinical procedure for treating life-threatening end-stage heart failure. Annually, 3000–4000 transplantations are performed worldwide. Heart transplantation has been performed successfully in patients of almost all ages, from newborn babies with untreatable heart defects to 70-year-olds. Transplant organs are explanted from deceased donors who have suffered brain death. The circulation is kept stable for several hours during which time a well-functioning heart can be excised. In Europe, as a rule, donor organs are matched to recipients by national or multinational organ-sharing organisations. ‘Eurotransplant’, for example, serves medical institutions in Germany, Austria, and the Benelux states. This enables 500–600 hearts to be transplanted in Germany each year. Since 1986, 650 heart transplantations have been performed at the German Heart Institute Berlin (GHIB) and more than 100 are performed per year. In recent years, heart-lung, single-, and double-lung transplantations have been added to the GHIB's surgical program, accounting for more than 40 operations since the institute's inception. Patients at the GHIB have ranged in age from 8 days to 68 years, including 48 patients under the age of 16 years. Approximately two-thirds of the patients suffered from dilated cardiomyopathy and one-third from coronary artery disease. Smaller groups of patients suffered from valvular or congenital heart disease. Patients were selected for heart transplantation when heart failure was untreatable by other means and when their life expectancy was estimated to be 6 months or less. Due to a shortage of donor organs, 30–50% of heart transplant candidates die before undergoing surgery. The 1-year survival rate for heart transplant recipients is 85–90% and remains above 70% after 5 years. The patients have been capable of near-normal levels of physical activity and the fact that most are able to return to work or school or active retirement has been very encouraging. Current immunosuppressive treatment consists of low dosages of cyclosporine A, azathioprine, and steroids. Additional immunosuppression is administered if rejection becomes apparent. Traditionally, rejection monitoring has been based upon frequent endomyocardial biopsies, initially performed weekly with a gradual increase in the interval over time. The GHIB has developed an electrophysiological method for recording the voltage of the intramyocardial action potential by means of a telemetric pacemaker system. This allows for daily recording and transmission of data via a telephone modem connection. In this manner, not only cellular but also humoral rejection can be detected. Biopsies, therefore, have become very rare while cases of fatal rejection remain extremely low. However, the long-term fate of heart transplant recipients is overshadowed by the development of accelerated graft coronary arteriosclerosis which is obviously related to chronic endothelial rejection. Thus, far less than 10% of the patients at the GHIB have exhibited this complication. Nevertheless, the development of graft disease has to be observed carefully. To reduce the frequency of death among heart transplantation candidates, mechanical cardiovascular support has been used to treat patients until a suitable donor heart became available, a concept termed ‘bridge-to-transplant’. The GHIB exclusively uses the ‘Berlin Heart’, a pneumatically-driven extracorporeal pulsatile system which is also the only commercially available system in Europe. Bridge-to-transplant was applied in more than 100 cases, the largest series of any single institution worldwide. Since the GHIB began employing this concept, 64 patients have been transplanted after support periods of up to 4 months. Although it is a successful addition to the heart transplantation process, the bridge-to-transplant concept cannot overcome the ever-widening gap between the number of patients requiring transplant and the number of donor organs. Presently, efforts are being made in Germany to pass legislation which require considering all brain-dead bodies as a potential source of donor organs and, thus, increase the number of transplant organs available. In the interim, however, the current dilemma calls for considering alternative solutions, such as xenotransplantation and the permanent artificial heart.

Preservation of the ischemic canine myocardium: A comparison of hypothermia, lidoflazine, and ketanserin

The purpose of this study was to determine whether ketanserin protects the globally ischemic canine heart and whether such protection, if present, is independent of that provided by hypothermia or calcium channel blockade with lidoflazine. Forty mongrel dogs, anesthetized with halothane, were divided into eight groups of five and subjected to one hour of global myocardial ischemia during hypothermic (30°C; groups 1 to 4) or normothermic (37°C; groups 5 to 8) cardiopulmonary bypass (CPB). Dogs in groups 1 and 5 served as controls with respect to prebypass myocardial protective therapy, and received only placebo (a normal saline bolus) prior to CPB. Before bypass, dogs in groups 2 and 6 received lidoflazine, 1.25 mg/kg intravenously (IV); those in groups 3 and 7 received ketanserin, 5 mg IV bolus, followed by a continuous infusion at 33 μg/min during bypass. Animals in groups 4 and 8 were given both lidoflazine and ketanserin according to the dosing schedules above. No type of pharmacologic or mechanical cardiovascular support was provided after termination of CPS. Postbypass hemodynamic performance and survival of the unsupported animal were assumed to reflect the degree of myocardial protection during CPS. One minute after bypass, mean arterial pressure and cardiac output were decreased in all groups. Cardiac output was lower in groups 5 to 8 (normothermic CPS) than in groups 1 to 4 (hypothermic CPB). After CPB, left ventricular filling pressures were elevated in all groups kept normothermic and in group 3 (hypothermic CPS plus ketanserin). By 15 minutes after CPS. there were no survivors in groups 5, 7, and 8. Sixty percent of animals in group 6 (normothermic CPB plus lidoflazine) survived to the end of the study. Relative odds of survival were increased 110-fold by hypothermia and sevenfold by lidoflazine. Conversely, treatment with ketanserin was associated with an increased likelihood of nonsurvival. It is concluded that, at the doses studied, ketanserin does not protect the canine myocardium against ischemic injury and may exert a detrimental effect when combined with calcium channel blockade in this setting.