Intra-aortic Balloon Pump Timing Research Articles

Intelligent System for the Classification of Arterial Blood Pressure Waveform Abnormalities Due to Mistiming in Intra-Aortic Balloon Pump

Cardiovascular diseases detection or diagnosis on appropriate time is crucial to avoid health complications. In this study, an advanced procedure for classifying changes in the blood pressure has been used analyzing the wave-forms inside the arterial system where such variation can occur due to improper timing in intra-aortic balloon pump (IABP) control. Inaccurate pressure extends with probable injury can be caused by improper timing in the heart valve in both pumping and compression of the balloon. This investigation focuses on accurately recognizing and classifying any irregularities in the artery wave-forms in IABP in the blood pressure initiated by mistiming. Accumulated blood pressure records are used for the progression of providing information to IABP trainer. The wave-forms require pre-handling employing image digitizing software to acquire automated identifications. Any undesirable image features have been removed using Wavelet in MATLAB software. Afterward, such features can be employed to develop a technique for arrangement depending on neural networks. The artificial neural network technique has used marked data to properly detect irregularities in wave-forms in vascular blood pressure due to improper IABP timing. As a result, the validation has proved to appropriately recognize and classify such anomalies, denoting a considerable prospect to improve patient protection with an efficacy of treatment in the area of cardiovascular prescription.

Intra-aortic and Intra-caval Balloon Pump Devices in Experimental Non-traumatic Cardiac Arrest and Cardiopulmonary Resuscitation.

Intra-aortic balloon pump (IABP) use during CPR has been scarcely studied. Intra-caval balloon pump (ICBP) may decrease backward venous flow during CPR. Mechanical chest compressions (MCC) were initiated after 10min of cardiac arrest in anesthetized pigs. After 5min of MCC, IABP (n = 6) or ICBP (n = 6) was initiated. The MCC device and the IABP/ICBP had slightly different frequencies, inducing a progressive peak pressure phase shift. IABP inflation 0.15s before MCC significantly increased mean arterial pressure (MAP) and carotid blood flow (CBF) compared to inflation 0.10s after MCC and to MCC only. Coronary perfusion pressure significantly increased with IABP inflation 0.25s before MCC compared to inflation at MCC. ICBP inflation before MCC significantly increased MAP and CBF compared to inflation after MCC but not compared to MCC only. This shows the potential of IABP in CPR when optimally synchronized with MCC. The effect of timing of intra-aortic balloon pump (IABP) inflation during mechanical chest compressions (MCC) on hemodynamics. Data from12 anesthetized pigs.

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.

Blood Pressure Monitoring During Intra-Aortic Balloon Pumping.

Blood Pressure Monitoring During Intra-Aortic Balloon Pumping.

Usefulness of Intra-aortic Balloon Pump in Patients With Cardiogenic Shock

Predictors of survival in cardiogenic shock (CS) treated with intra-aortic balloon pump (IABP) are not clearly understood. In this retrospective study, we sought to evaluate patient characteristics and impact of timing of IABP in treatment of CS. Patients presenting to the Yale New Haven Hospital in CS who received IABP between February 2013 and April 2017 were included in the study. We assessed baseline characteristics and clinical predictors of 30-day mortality. Hundred ninety-three (n = 193) patients were included in this study. Mean age was 68.8 ± 14.5 years. Thirty percent (30%) were women, 38% had cardiac arrest, and left ventricular ejection fraction was 33.7 ± 14.9%. Overall 30-day mortality was 36%. Thirty-day mortality was 24% when IABP was placed within less than 1 hour of onset of CS versus 49% when implanted ≥1 hour after recognition of CS (p = 0.001). Mortality was 18%, 21%, 36%, and 74% for patient requiring 0, 1, 2, and 3 or more inotropes after IABP placement (p < 0.001). In multivariate analysis, advancing age, cardiac arrest on presentation, time to IABP implantation, and number of inotropes needed after IABP implantation predicted 30-day mortality. In the 193 patients, 134 (69.4%) presented with CS from ACS and 59 (30.6%) with CS from non-ACS-related causes. No difference in mortality was noted between the ACS and non-ACS groups 34.3% versus 40.7% (p = 0.39). In conclusion, early use of IABP in CS was associated with significant improvement in 30-day mortality regardless of the etiology of CS. Continued need for significant inotropic support after IABP is associated with worse prognosis and maybe used as an indicator for need to escalate to higher levels of support.

Predictors of mortality in patients with cardiogenic shock treated with primary percutaneous coronary intervention and intra-aortic balloon counterpulsation.

Cardiogenic shock remains the most serious complication of patients hospitalized with acute myocardial infarction (AMI). Early revascularization is the cornerstone of invasive therapy, while mechanical support with intra-aortic balloon pump (IABP) is debatable. From our institutional shock registry we sought to determine predictors of in-hospital mortality-including the aspect of IABP timing-and to develop a clinical risk score for shock patients with AMI. From January 2005 till December 2010, 102 patients with cardiogenic shock due to AMI treated with primary percutaneous coronary intervention (PCI) and IABP were analyzed. Univariate and multivariate logistic regression analyses were used to identify independent predictors of in-hospital mortality. Logistic regression analysis and receiver-operating curves were used to generate a mortality risk score. The mean age of the cohort was 70.1 ± 11.0 years and 70 % were men. One third of patients had a non-ST segment elevation myocardial infarction and 30 % had to be resuscitated before coronary intervention. Mean left ventricular ejection fraction was 25 %. After admission, 23 % of patients developed an acute renal failure and 10 % needed renal dialysis during hospital stay. In 52 % of patients IABP therapy was initiated after primary PCI, while the remaining patients had an IABP-assisted primary PCI. All-cause in-hospital mortality was 40.2 %. Using multivariate analysis, age (odds ratio [OR] 1.08, p = 0.006), resuscitation before PCI (OR 3.46, p = 0.045), vasopressor use (OR 7.88, p = 0.003), acute renal failure (OR 11.18, p = 0.001), and IABP implantation after PCI (OR 4.36, p = 0.011) were independently associated with in-hospital mortality. Based on these predictors, a mortality-risk score was calculated as follows: 1.5 × IABP timing before PCI + 0.1 × age + resuscitation before PCI + 2 × vasopressor use + 2.5 × acute renal failure. Using a cut-off value of 10.4, this score had a specificity of 83 % and a sensitivity of 82 % for prediction of in-hospital death. We identified age, vasopressor use, resuscitation before PCI, acute renal failure and IABP implantation after PCI as independent predictors of in-hospital mortality in patients with cardiogenic shock due to AMI. The timing of IABP insertion was the only modifiable factor predicting in-hospital mortality in our cohort. Consequently, balloon pumping should be started before PCI to improve outcome of cardiogenic shock patients.

Single-Centre Experience with Perioperative Use of Intraaortic Balloon Pump in Cardiac Surgery

Intraaortic balloon pump (IABP) is frequently used in cardiac surgery in order to prevent or treat low cardiac output syndrome. Although being widely used and forming the first line therapy in these haemodynamically unstable patients despite maximal medication, optimal timing for IABP insertion is still discussed. This retrospective study evaluates hospital outcomes of patients receiving IABP at preoperative, intraoperative and postoperative periods during cardiac surgery. Between 2006 and 2012, 2196 patients underwent open cardiac surgery in our centre. IABP was used in 121 (5.4%) patients. Nine patients had preoperative IABP insertion, 76 patients (62.8%) had intraoperative insertion to ease weaning from cardiopulmonary bypass, and 36 patients (29.8%) had postoperative insertion in the intensive care unit mainly due to refractory haemodynamic instability. Hospital outcomes of these 121 patients were analysed retrospectively. The majority of the patients were male (men 89, 73.6% and women 32, 26.4%; mean age was 65.9±11.5 years). Among the cohort 87 (71.9%) underwent isolated coronary artery bypass surgery (CABG) and the rest (34 patients, 28.1%) were operated for valve disease with/without CABG or for CABG with carotid endarterectomy, left ventricular aneurysm repair, post myocardial infarction ventricular septal defect or pathologies involving ascending aorta. The overall hospital mortality of the whole cohort was 27.3%. Mortality rates according to IABP timing were 33.3%, 19.7% and 41.7% for pre, intra and postoperative insertion, respectively. Logistic regression analysis identified female gender, low ejection fraction (<30%), complex surgery and postoperative insertion as risk factors for mortality. IABP insertion timing in cardiac surgery is crucial and many reports advocate early insertion since patient outcomes are poor for late insertions. This single centre study also confirms that the least favourable results are among patients with postoperative IABP insertion.

End-diastolic flow reversal limits the efficacy of pediatric intra-aortic balloon pump counterpulsation

Counterpulsation with an intra-aortic balloon pump (IABP) has not achieved the same success or clinical use in pediatric patients as in adults. In a pediatric animal model, IABP efficacy was investigated to determine whether IABP timing with a high-fidelity blood pressure signal may improve counterpulsation therapy versus a low-fidelity signal. In Yorkshire piglets (n=19; weight, 13.0 ± 0.5 kg) with coronary ligation-induced acute ischemic left ventricular failure, pediatric IABPs (5 or 7 mL) were placed in the descending thoracic aorta. Inflation and deflation were timed with traditional criteria from low-fidelity (fluid-filled) and high-fidelity (micromanometer) blood pressure signals during 1:1 support. Aortic, carotid, and coronary hemodynamics were measured with pressure and flow transducers. Myocardial oxygen consumption was calculated from coronary sinus and arterial blood samples. Left ventricular myocardial blood flow and end-organ blood flow were measured with microspheres. Despite significant suprasystolic diastolic augmentation and afterload reduction at heart rates of 105 ± 3 beats per minute, left ventricular myocardial blood flow, myocardial oxygen consumption, the myocardial oxygen supply/demand relationship, cardiac output, and end-organ blood flow did not change. Statistically significant end-diastolic coronary, carotid, and aortic flow reversal occurred with IABP deflation. Inflation and deflation timed with a high-fidelity versus low-fidelity signal did not attenuate systemic flow reversal or improve the myocardial oxygen supply/demand relationship. Systemic end-diastolic flow reversal limited counterpulsation efficacy in a pediatric model of acute left ventricular failure. Adjustment of IABP inflation and deflation timing with traditional criteria and a high-fidelity blood pressure waveform did not improve IABP efficacy or attenuate flow reversal. End-diastolic flow reversal may limit the efficacy of IABP counterpulsation therapy in pediatric patients with traditional timing criteria. Investigation of alternative deflation timing strategies is warranted.

IABP Timing and Ventricular Performance - Comparison between a Compliant and a Stiffer Aorta: A Hybrid Model Study Including Baroreflex

The aim of this study was to investigate the effects of the intra aortic balloon pump (IABP) and of aortic compliance on left ventricular performance, including the effects of baroreflex control. The study was conducted using a hybrid cardiovascular simulator, including a computational cardiovascular sub-model, a hydraulic sub-model of the descending aorta, and a baroreflex computational sub-model. A 40 cc balloon was inserted into a rubber tube component of the hydraulic sub-model. A comparative analysis was conducted for two aortic compliances (C1 = 2.4 and C2 = 1.43 cm3/mmHg, corresponding to an aortic pulse pressure of 23 mmHg and 35 mmHg, respectively), driving the balloon for different trigger timings. Under C1 conditions, the IABP induced higher effects on baroreflex activity (decrement of sympathetic efferent activity: 10% for C1 and 14.7% for C2) and ventricular performance (increment of cardiac output (CO): 3.7% for C1 and 5.2% for C2, increment of endocardial viability ratio (EVR): 24.8% for C1 and 55% for C2). The best balloon timing was different for C1 and C2: inflation trigger timing (from the dicrotic notch) -0.09 s for C1 and -0.04 s for C2, inflation duration 0.25 s for C1 and 0.2 s for C2. Early inflation ensures better EVR, CO, and an increment of the afferent nerve activity, hence causing peripheral resistance and heart rate to decrease. The best balloon timing depends on aortic compliance, thus suggesting the need for a therapy tailored to the specific conditions of individual patients.

Certification Review

1.Which of the following is a “total artificial heart” device? A.JarvikB.HeartWareC.DeBakeyD.AbioCorAnswer: D. The AbioCor is a total artificial heart device. The other options are all left ventricular assist devices.Holleran R, ed. Air and Surface Patient Transport: Principles and Practice. 4th ed. St. Louis: Mosby; 2010: 467.2.Pump failure occurs during transport of a 56-year-old man with an intra-aortic balloon pump (IABP) in place. Which of the following interventions is appropriate? A.Stop the pump, clamp the catheter, and place the patient in the left lateral position.B.Stop the pump and inflate the IABP catheter once every 3–5 minutes manually with a 60-mL syringe.C.Begin cardiopulmonary resuscitation and place the IABP in the internal 80 default setting.D.Decrease the inflation volume in the catheter and place the pump on a 1:3 timing mode.Answer: B. If pump failure occurs during transport, stop the pump and inflate the IAB catheter every 3–5 minutes manually with a 60-mL syringe. For an IAB rupture, the team should stop the pump, clamp the catheter, and place the patient in the left lateral position. Begin CPR and place the IABP in the internal 80 default setting if the patient arrests.Holleran R, ed. Air and Surface Patient Transport: Principles and Practice. 4th ed. St. Louis: Mosby; 2010: 444.3.Which of the following IABP timing errors will result in retrograde coronary blood flow? A.Early inflationB.Late inflationC.Early deflationD.Late deflationAnswer: C. Early deflation will cause retrograde coronary blood flow. Early inflation results in premature closing of the aortic valve, causing aortic regurgitation. Late inflation results in suboptimal coronary perfusion. Late deflation increases resistance or afterload.Holleran R, ed. Air and Surface Patient Transport: Principles and Practice. 4th ed. St. Louis: Mosby; 2010: 442.4.How often during air medical transport should the flight crew manually autofill the IABP catheter? A.Every 2,000 ft of ascent and 1,000 ft of descentB.Every 1,000 ft of ascent and 2,000 ft of descentC.Every 1,000 ft of ascent and descentD.Every 2,000 ft of ascent and descentAnswer: A. When a manual autofill is required, the transport crew should perform it with every 2,000 feet of ascent and every 1,000 feet of descent. New generations of IABPs have sensors that detect altitude changes, and they will perform the autofill automatically.Holleran R, ed. Air and Surface Patient Transport: Principles and Practice. 4th ed. St. Louis: Mosby; 2010: 442.5.The goal of inflation during IABP catheterization is to produce a ____________, which optimizes diastolic augmentation. A.Rapid rise in systolic pressureB.Rapid rise in aortic pressureC.Rapid decrease in systolic pressureD.Rapid decrease in aortic pressureAnswer: B. The goal of inflation is to produce a rapid rise in aortic pressure to optimize diastolic pressure, thereby increasing oxygen supply to the coronaries.Holleran R, editor. Air and surface patient transport: Principles and practice. 4th ed. St. Louis: Mosby; 2010: 441.

Intra-aortic Balloon Pump Timing: Review of Evidence Supporting Current Practice

Intra-aortic balloon counterpulsation is the most widely used therapy for support of a compromised left ventricle. The principles of counterpulsation were developed in the 1950s, and intra-aortic balloon pumps have been used for more than 40 years. Despite this long-standing clinical use, many of the timing practices have continued almost unchanged from their inception. One of the most important aspects of the pumps is timing, or synchronizing the action of the device with the cardiac cycle. The principles of timing are based on the physiological objectives of counterpulsation; however, research into alternative timing methods has led to conflicting and often confusing information on the appropriate timing method for a specific clinical situation or patient. Although a body of knowledge is available, much of the research is dated and covers only specific timing methods or populations of patients. Further evidence is needed to support the selection of timing methods and determine the clinical benefits of the various methods.

Intra-aortic Balloon Pump Implantation Does Not Affect Long-Term Survival after Isolated CABG in Patients with Acute Myocardial Infarction

Intra-aortic balloon pump (IABP) is an established therapy to support patients with heart failure during coronary artery bypass grafting (CABG). The impact of the timing of IABP on the hospital course and on follow-up is of particular clinical interest. The purpose of this study was to analyze the relationship between the time of IABP implantation and its impact on early, mid- and long-term survival in patients with acute myocardial infarction (AMI) who underwent emergent CABG for NSTEMI and STEMI. A total of 472 patients with AMI (NSTEMI and STEMI) underwent emergency CABG at our institution; 158 of them additionally received IABP support. Fifty-seven (36 %) patients received preoperative and 101 (64 %) patients underwent intraoperative IABP implantation. Endpoints were in-hospital und follow-up (mean duration 37 ± 28 months) survival. Overall in-hospital mortality was 17.1 % (n = 27): 17.6 % (n = 10) in the preoperative group and 16.8 % (n = 17) in the intraoperative group ( P = ns). Mid- and long-term survival rates were comparable for both groups 78.6 % vs. 73.7 %, 71.4 % vs. 68.7 % and 64.3 % vs. 54.6 % at 1, 3 and 5 years, respectively ( P = ns). This study demonstrates that CABG with IABP support in high-risk patients with AMI can be performed with acceptable in-hospital and long-term survival rates. The decision for IABP placement should consider the preoperative clinical condition and the intraoperative course of each patient. IABP placement does not appear to affect the long-term outcome after isolated CABG in patients with AMI.

Biventricular Pacing in Conjunction with Epicardial Atrial Pacing Adversely Affects Timing of Intra-Aortic Balloon Pump

A case of accidental triggering of an intra-aortic balloon pump during systole is presented. The patient had a cardiac resynchronization therapy device in place preoperatively for heart failure. A temporary epicardial atrial pacing wire was used during separation from cardiopulmonary bypass for rate control. An intra-aortic balloon pump was necessary for separation from bypass. Although the pacemaker functioned properly, the intra-aortic balloon triggered from the atrial pacing spike and was inflated during systole. Pacemaker and intra-aortic balloon electronics and timing settings that caused this are discussed in detail. Suggestions for prevention are presented.

Thrombocytopenia in Patients Treated with Heparin, Combination Antiplatelet Therapy, and Intra‐Aortic Balloon Pump Counterpulsation

Determine the incidence and timing of intra-aortic balloon pump (IABP)-associated thrombocytopenia, if concomitant antiplatelet agents increase the incidence of thrombocytopenia, and the incidence of heparin-induced thrombocytopenia (HIT) in a contemporary IABP population. Previous studies predate the current practice of treating acute coronary syndrome patients with heparin and aspirin plus thienopyridines and glycoprotein IIb/IIIa receptor antagonists such that data are unavailable to determine if their co-administration worsens IABP-associated thrombocytopenia. A retrospective cohort study of adult IABP patients (n = 107) from 2002 to 2006 was performed to determine the indication for and duration of counterpulsation, platelet counts during and for 7 days postcounterpulsation, medications potentially contributing to thrombocytopenia, and HIT antibody results if obtained. Thrombocytopenia, defined as platelets <150,000/mL or >50% decrease from baseline, occurred in 57.9% of patients. Overall, platelets declined to 60.2 +/- 22.8% of baseline with the mean (+/- standard deviation) nadir on day 2.8 +/- 2.0. Comparing patients who received heparin, aspirin, thienopyridines, and glycoprotein IIb/IIIa antagonists (n = 44) versus heparinized patients +/- aspirin (n = 45), platelet nadirs were 62.7 +/- 20.9% versus 58.3 +/- 23.9% of baseline levels, respectively (P = 0.42). The incidence of HIT was 2.8% in the entire cohort. IABP-associated thrombocytopenia occurred in 57.9% of this cohort. HIT was diagnosed in 2.8% and should be considered as a diagnosis if platelet counts do not stabilize or continue to fall after 3-4 days of counterpulsation. Increased use of antiplatelet therapy does not impact the degree of thrombocytopenia although the current practice of prompt IABP removal may offset this effect.

Timing of intra-aortic balloon pump support and 1-year survival

The relationship between the timing of intra-aortic balloon pump (IABP) support and surgical outcome remains a subject of debate. Peri-operative mechanical circulatory support is commenced either prophylactically or after increasing inotropic support has proved inadequate. This study evaluates the effect timing of IABP support on the 1-year survival of patients undergoing cardiac surgery. From April 1997 to September 2002, 7698 consecutive cardiac surgical procedures were performed. This included 5678 isolated coronary artery bypasses (CABGs), 1245 isolated valve procedures and 775 simultaneous CABG and valve procedures. IABP support was required in 237 patients (3.1%). Twenty-seven patients (0.35%) were classed as high-risk and received preoperative IABP support, 25 patients (0.32%) were haemodynamically compromised and required preoperative IABP support, 120 patients (1.56%) required intra-operative IABP support, and 65 patients (0.84%) required post-operative IABP support. Multiple variables were offered to a Cox proportional hazards model and significant predictors of 1-year survival were identified. These were used to risk adjust Kaplan-Meier survival curves. 1-year follow-up was complete and 450 deaths (5.8%) were recorded. The significant independent predictors of increased mortality at 1-year (P<0.05, HR=hazard ratio) were post-operative renal failure (HR=3.5), increasing EuroSCORE (HR=1.2), post-operative myocardial infarction (HR=3.7), post-operative IABP (HR=4.1) intra-operative IABP (HR=2.8), post-operative stroke (HR=2.5), increasing number of valves (HR=1.6), ejection fraction <30% (HR=1.3) and triple-vessel disease (HR=1.3). After risk-adjustment, 1-year survival for patients who required intra-operative IABP support was significantly greater than for those patients who required IABP support in the post-operative period. Patients who warrant IABP support in the post-operative setting have a significantly increased mortality at 1-year when compared to any other group. Therefore, earlier IABP support as part of surgical strategy may help to improve the outcome.

INVITED COMMENTARY

This article describes a novel algorithm to predict the dicrotic notch for timing intraaortic balloon pump (IABP) counterpulsation. The algorithm uses pressure readings from a high fidelity fiberoptic micromanometer embedded in the tip of the IABP. This system was evaluated in 27 patients with low ejection fractions who were undergoing cardiac operations. Balloon inflation and deflation were accurate in the vast majority of arrhythmic beats. Pressure-volume data were shown that suggests this technology will provide better support than conventionally timed IABP counterpulsation.Since the initial use of IABP counterpulsation, attempts have been made to improve the timing of balloon inflation and deflation, particularly in patients with arrhythmias. The present attempt at such a system appears to provide good results, at least in a limited number of patients, but obstacles remain. One potential problem with using pressure data from transducers embedded in the tip of the IABP is artifact. The system is essentially a refined pulse pressure-based sensing algorithm that derives flow from high fidelity pressure measurements. Thus the system is vulnerable to timing errors due to artifacts in the pressure data. This was not encountered in the study, but it can occur even with readings from a fiberoptic micromanometer. Another potential problem is a malignant arrhythmia that generates pulse pressures below the threshold for detection. These are arguably the most dangerous arrhythmias to a patient. What are the limits for pulse pressure and first derivative of pressure relative to time (dP/dt) below which the system becomes inaccurate? A third issue is the rate limit of the system. It is presumably the same as the limit for IABPs that use conventional electrocardiogram or pressure triggers. Ultimately, the problem with effective IABP counterpulsation during a tachyarrhythmia becomes shuttling helium back and forth in the IABP and not tracking the dicrotic notch.The final question relates to cost and indications for use. Catheters with embedded micromanometers cost more than conventional IABP catheters, but an outcome benefit for this novel IABP timing system has not yet been demonstrated. Determining the benefit in terms of survival, morbidity, and duration of hospitalization will be crucial for defining the role of this technology in clinical practice. This article describes a novel algorithm to predict the dicrotic notch for timing intraaortic balloon pump (IABP) counterpulsation. The algorithm uses pressure readings from a high fidelity fiberoptic micromanometer embedded in the tip of the IABP. This system was evaluated in 27 patients with low ejection fractions who were undergoing cardiac operations. Balloon inflation and deflation were accurate in the vast majority of arrhythmic beats. Pressure-volume data were shown that suggests this technology will provide better support than conventionally timed IABP counterpulsation. Since the initial use of IABP counterpulsation, attempts have been made to improve the timing of balloon inflation and deflation, particularly in patients with arrhythmias. The present attempt at such a system appears to provide good results, at least in a limited number of patients, but obstacles remain. One potential problem with using pressure data from transducers embedded in the tip of the IABP is artifact. The system is essentially a refined pulse pressure-based sensing algorithm that derives flow from high fidelity pressure measurements. Thus the system is vulnerable to timing errors due to artifacts in the pressure data. This was not encountered in the study, but it can occur even with readings from a fiberoptic micromanometer. Another potential problem is a malignant arrhythmia that generates pulse pressures below the threshold for detection. These are arguably the most dangerous arrhythmias to a patient. What are the limits for pulse pressure and first derivative of pressure relative to time (dP/dt) below which the system becomes inaccurate? A third issue is the rate limit of the system. It is presumably the same as the limit for IABPs that use conventional electrocardiogram or pressure triggers. Ultimately, the problem with effective IABP counterpulsation during a tachyarrhythmia becomes shuttling helium back and forth in the IABP and not tracking the dicrotic notch. The final question relates to cost and indications for use. Catheters with embedded micromanometers cost more than conventional IABP catheters, but an outcome benefit for this novel IABP timing system has not yet been demonstrated. Determining the benefit in terms of survival, morbidity, and duration of hospitalization will be crucial for defining the role of this technology in clinical practice. Automatic Intraaortic Balloon Pump Timing Using an Intrabeat Dicrotic Notch Prediction AlgorithmThe Annals of Thoracic SurgeryVol. 79Issue 3PreviewThe efficacy of intraaortic balloon counterpulsation (IABP) during arrhythmic episodes is questionable. A novel algorithm for intrabeat prediction of the dicrotic notch was used for real time IABP inflation timing control. Full-Text PDF

Hemodynamic effects of new intra-aortic balloon counterpulsation timing methods in patients: A multicenter evaluation

Background To test whether later intra-aortic balloon pump (IABP) deflation approaching or simultaneous with left ventricular ejection would improve hemodynamics and myocardial efficiency with the use of new balloon deflation methods, 4 IABP timing techniques were evaluated in 43 patients. Methods and Results Later balloon deflation produced significantly greater percentage changes in mean aortic pressure (6% vs 1%), systolic pressure time index (–27% vs –20%), diastolic pressure time index (35% vs 19%), and the systolic pressure-time index/diastolic pressure-time index ratio (97% vs 51%), respectively. However, these changes increased peak systolic pressure (–15% vs –11%). Cardiac output and stroke volume indexes were not significantly altered over the 4 settings. Conclusions These data suggest that systemic hemodynamics and myocardial efficiency may be improved by later balloon deflation approaching left ventricular ejection in comparison to conventional IABP timing. (Am Heart J 1999;137:1129-6.)

Estimation of timing errors for the intraaortic balloon pump use in pediatric patients.

The use of the intraaortic balloon pump (IABP) for managing acute left ventricular failure in pediatric patients is less successful than in adults. It is often reported that rapid pediatric heart rates make accurate timing difficult to achieve. Traditional IABP theory requires that the balloon inflate during diastole (after aortic valve closure), for optimum coronary pressure and flow augmentation, and deflate just before the next systole for optimal ventricular afterload reduction. Errors in timing balloon inflation and deflation may result in the reduced IABP efficacy seen in children. To investigate timing errors when using the traditional IABP inflation and deflation markers in pediatric patients, six patients (age, 2.2+/-1.4 years; weight, 11.5+/-3.9 kg) were studied intraoperatively. Radial artery pressure (RAP) waveforms from a standard, fluid-filled pressure monitoring system were recorded on an FM data tape recorder simultaneously with high-fidelity, aortic root pressure waveforms, aortic root flow waveforms, and M-mode echocardiography. For each patient, a sequence of five recorded waveforms was analyzed. The mean +/- standard deviation of the time delay between aortic root and RAP markers and percentage delay of the corresponding part of the cardiac cycle were determined. When compared with aortic root waveforms, the RAP waveform consistently showed a delay in the IABP timing markers. A 107+/-23 msec (53+/-11%) delay in diastolic inflation and a 92+/-11 msec (40+/-4%) delay in presystolic deflation was found. If IABP timing to the RAP markers were to be used, the delay in IABP inflation would result in reduced diastolic augmentation, and the delay in IABP deflation into the systolic period would increase afterload. M-mode echocardiography provided timing markers that were identical to those provided by high-fidelity aortic root pressure waveforms. The combined effect of these delays on IABP function could substantially reduce the efficacy of the IABP in pediatric patients, indicating the need for more accurate indices for IABP timing in this patient group.

Modeling the dynamic interaction between left ventricle and intra-aortic balloon pump

An analog model is developed to characterize how alterations of some intra-aortic balloon pump (IABP) parameters affect the coupling between left ventricle (LV) and aorta. The time-varying elastance concept is applied to modeling both active components (LV and IABP) in the assisted circulation. Pressure and flow waveforms in the system are determined by numerically integrating five simultaneous state equations that represent the system dynamics. Validity of the model is supported by good agreement between model predictions and published data on LV pressure-volume (P-V) loops, end-systolic P-V relations, and hemodynamic consequences of adjusting IABP timing and speed. The model also predicts that increasing balloon volume increases the diastolic aortic pressure augmentation but has a negative effect of increasing LV load. Increasing balloon diameter over length ratio and holding a constant volume increases the diastolic augmentation and decreases the LV demand. Positioning the balloon closer to the heart improves systolic unloading but affects neither diastolic augmentation nor cardiac output. These results suggest that occlusivity is a major determinant of IABP effectiveness and plays a more important role than balloon volume and position.