Intra-aortic Balloon Counterpulsation Support Research Articles

ECMO and Right Ventricular Failure: Review of the Literature.

Right ventricular (RV) failure is the inability of the RV to maintain sufficient cardiac output in the setting of adequate preload, due to either intrinsic injury to the RV or increased afterload. Medical treatment of RV failure should include optimizing preload, augmenting contractility with vasopressors and inotropes, and considering inhaled pulmonary vasodilators. However, when medical therapies are insufficient, mechanical circulatory support (MCS) is needed to maintain systemic and RV perfusion. The data on MCS for isolated RV failure are limited, but extracorporeal membrane oxygenation (ECMO) appears to be the most efficient and effective modality. For patients with isolated RV failure from acute hypoxemic respiratory failure, veno-venous (VV) ECMO is an appropriate initial configuration, even if the patient is in shock. With primary RV injury or RV failure with concomitant left ventricle (LV) failure, however, venoarterial (VA) ECMO is indicated. Both modalities provide indirect support to the RV by reducing preload, reducing RV wall tension, and delivering oxygenated blood to the coronary circulation. Peripheral cannulation is required in VV-ECMO and is most commonly used in VA-ECMO, allowing for rapid cannulation even in emergencies. Changes in pulsatility on an arterial catheter waveform can indicate changes in clinical status including changes in myocardial function, inadequate preload, worsening RV failure, and excessive VA-ECMO support leading to an elevated LV afterload. Myocardial function may be improved by titration of inotropes or vasodilators, utilization of an Impella or an intra-aortic balloon counterpulsation support devices, or by changes in VA-ECMO support.

Intra-Aortic Balloon Counterpulsation in Patients With Chronic Heart Failure and Cardiogenic Shock: Clinical Response and Predictors of Stabilization

ObjectiveThe aim of this work was to characterize the clinical response and identify predictors of clinical stabilization after intra-aortic balloon counterpulsation (IABP) support in patients with chronic systolic heart failure in cardiogenic shock before implantation of a left ventricular assist device (LVAD). BackgroundLimited data exist regarding the clinical response to IABP in patients with chronic heart failure in cardiogenic shock. MethodsWe identified 54 patients supported with IABP before LVAD implantation. Criteria for clinical decompensation after IABP insertion and before LVAD included the need for more advanced temporary support, initiation of mechanical ventilation or dialysis, increase in vasopressors/inotropes, refractory ventricular arrhythmias, or worsening acidosis. The absence of these indicated stabilization. ResultsClinical decompensation after IABP occurred in 23 patients (43%). Both patients who decompensated and those who stabilized had similar hemodynamic improvements after IABP support, but patients who decompensated required more vasopressors/inotropes. Clinical decompensation after IABP was associated with worse outcomes after LVAD implantation, including a 3-fold longer intensive care unit stay and 5-fold longer time on mechanical ventilation (P < .01 for both). Although baseline characteristics were similar between groups, right and left ventricular cardiac power indexes (cardiac power index = cardiac index × mean arterial pressure/451) identified patients who were likely to stabilize (area under the receiver operating characteristic curve = 0.82). ConclusionsAmong patients with chronic systolic heart failure who develop cardiogenic shock, more than one-half of patients stabilized with IABP support as a bridge to LVAD. Baseline measures of right and left ventricular cardiac power, reflecting work performed for a given flow and pressure, may allow clinicians to identify patients with sufficient contractile reserve who will be likely to stabilize with an IABP versus those who may need more aggressive ventricular support.

Is there a place for intra-aortic balloon counterpulsation support in acute right ventricular failure by pressure-overload?

BackgroundMost therapeutic strategies for acute right ventricular failure (RVF) by pressure-overload are directed to improve cardiac output and coronary perfusion pressure by vasopressive agents. The eventual role of intra-aortic balloon counterpulsation (IABP) support remains questionable. This study investigates the contribution of IABP for acute RVF by pressure-overload, in comparison with phenylephrine (PE) and norepinephrine (NOR). MethodsAcute RVF is induced by fixed pulmonary artery constriction in 6 pigs, pursuing a 50% reduction of cardiac output. Assessment of the treatment interventions included biventricular PV-loop analysis, and continuous measurement of aortic and right coronary artery flow. ResultsRestoration of baseline cardiac output was only observed by administration of NOR (Baseline=3.82±1.52ml/min — RVF=2.03±0.59ml/min — IABP=2.45±0.62ml/min — PE=2.98±0.63ml/min — NOR=3.95±0.73ml/min, p<0.001). NOR had most effect on biventricular contractility (PRSW-slope-RV: IABP +24% — PE +59% — NOR +208%, p<0.001 and PRSW-slope-LV: IABP +36% — PE +53% — NOR +196%, p<0.001), heart rate acceleration (IABP +7% — PE +12% — NOR +51%, p<0.001), and RCA flow (IABP +31% — PE +58% — NOR +180%, p<0.001), concomitant to a higher increase of LV-to-RV pressure ratio (IABP: +7% versus −3%, PE: +36% versus +8%, NOR: +101% versus 42%). The hemodynamic contribution of IABP was limited, unless a modest improvement of LV compliance during PE and NOR infusion. ConclusionIn a model of acute pressure-overload RV failure, IABP appears to offer limited hemodynamic benefit. The administration of norepinephrine is most effective to correct systemic output and myocardial perfusion through adding an inotropic and chronotropic effect to systemic vasopression.

Diabetic patient with three-vessel disease and left main involvement. Surgery yes, but not always

Coronary artery disease (CAD) is known to be the main cause of morbidity and mortality in patients with diabetes mellitus. Although they do not often show typical recognized symptoms, diabetic patients suffer from more extensive CAD and hence higher incidence of multi-vessel CAD than in non-diabetic subjects. Literature has given the strength of evidence in favor of surgical revascularization in diabetic patients with multi-vessel disease. We report the case of a 61-year old active smoker and diabetic man with atypical symptoms and positive treadmill test. The coronary angiography revealed a severe three-vessel disease and distal left main involvement (SYNTAX score = 49). As the patient refused to follow heart team indication to undergo coronary bypass grafting, a percutaneous coronary intervention was successfully performed with intra-aortic balloon counterpulsation support and intravascular ultrasound optimization. The mid-term outcome was good.

Impact of intraaortic balloon counterpulsation in patients with acute myocardial infarction and cardiogenic shock

Purpose: Intraaortic balloon counterpulsation (IABP) is recommended for acute myocardial infarction (MI) patients who presenting with cardiogenic shock. Recently, a randomized trial revealed that IABP support did not reduce 30-day mortality. We aimed to determine the impact of IABP support on the short- and long-term mortality. Methods: A total of 774 patients with acute MI and cardiogenic shock were selected from the Korea Working Group on Myocardial Infarction Registry between December 2007 and December 2010. Primary outcomes were mortality at one-month and one-year. Results: The patients who were treated with IABP support was 395 and the patients not treated with IABP was 379. The patients treated with IABP were more ST-segment elevation myocardial infarction, anterior ischemia on electrocardiogram, and had undergone more PCI and coronary artery bypass surgery than patients not treated with IABP. Infarct area was larger and rate of statin prescription during hospitalization was higher in patients treated with IABP. One-month mortality and one-year mortality were significantly lower in patients treated with IABP compared to patients not treated with IABP (45.3 vs 54.6%, p=0.024; 46.8 vs 55.4%, p=0.041, respectively). By multivariate logistic regression analysis after adjusting confounding variables, IABP support was associated with neither one-month mortality nor one-year mortality (OR 0.62, 95% CI 0.348-1.098, p=0.101; OR 0.64, 95% CI 0.382-1.085, p=0.098, respectively). However, Cox proportional hazard model showed that long-term survival was significantly better in patients treated with IABP (log rank p=0.034). ![Figure][1] Conclusions: This study showed that IABP support was not associated with reduced one-month mortality but associated with long-term mortality benefit. [1]: pending:yes

Influence of Gender on Postoperative Outcome after Intra-aortic Balloon Counter-Pulsation and Cardiac Surgery

Female gender is an established risk factor for worse outcomes after cardiac surgery, and women are more likely to experience postoperative complications. Our aim was to analyze the influence of gender on outcome and postoperative complications after the use of intra-aortic balloon counter-pulsation (IABP) in cardiac surgery patients. Fifty-seven consecutive female patients (mean age: 73 ± 9 years) requiring an IABP at our department from January 2007 to January 2010 were retrospectively analyzed and compared with 182 male patients receiving IABP support within the same period. The collected data included patient demographics, preoperative state, operative details, postoperative pharmacological treatment, IABP-associated complications, and inhospital mortality. Preoperative mortality risk was calculated by logistic EuroSCORE. There were no differences regarding the type of operation, preoperative renal or hepatic failure, though the prevalence of peripheral artery occlusive disease was higher in men. Furthermore, female patients receiving an IABP were significantly older (73 ± 9 vs. 67 ± 10 years), had a higher ejection fraction (EF) (45% ± 24% vs. 36% ± 14%), and had a higher EuroSCORE (25% ± 20% vs. 19% ± 17%; p < 0.05). Postoperative catecholamine support was significantly higher in the female patients. Women had a prolonged length of stay (LOS) at the ICU (10.64 ± 9.7 vs. 7.6 ± 7.6 days), higher incidence of renal replacement therapy, and a higher mortality (19 [19.4%] vs. 35 [33.9%]; p < 0.05) after the use of IABP. Women have a worse outcome after the use of IABP, including LOS at the ICU, postoperative renal failure, and inhospital mortality, despite higher EF, when compared with men.

The Janus of Oxidative Stress Signaling in Different Pathophysiological Conditions

The Janus of Oxidative Stress Signaling in Different Pathophysiological Conditions

Decrease of total antioxidative capacity in developed low cardiac output syndrome.

Background. It has been known that cardiac surgery induces an oxidative stress. The persistent oxidative stress during reperfusion may lead to depressed myocardial function resulting in low cardiac output syndrome (LCOS) necessitating inotropic or intra-aortic balloon counterpulsation support. Total antioxidant capacity (TAC) is a measurement of oxidative stress in tissues. The purpose of this study was to examine the TAC differences during coronary artery bypass graft (CABG) operation in patients who have developed LCOS and who have not. Material and Methods. Seventy-nine patients were enrolled in the study. Central venous blood samples were obtained immediately before surgery, during operation, and at the end of surgery to assess TAC. Clinical data regarding patient demographics and operative outcomes were prospectively collected and entered into our clinical database. Results. LCOS developed in 8 patients (10.12%). The TAC has decreased sharply in the LCOS patients compared with those who did not develop LCOS (P < 0.001) during operation. In addition, the receiver operating characteristic (ROC) area was 0.879. Conclusion. TAC has decreased during operation in a significant proportion of patients undergoing isolated CABG, and this is more prominent and serious and might be an independent variable in patients who have developed LCOS. This may be related to intraoperative misadventure or inadequate myocardial antioxidative protection. Routine measurement of the TAC during operation may provide information for assessment of the LCOS development.

Myocardial revascularization of patients with diffuse coronary artery disease

Off-pump coronary artery bypass grafting (off-pump CABG) after off-pump coronary endarterectomy (CE) for myocardial revascularization is a way to rescue the patients with diffuse coronary artery disease (CAD). This study retrospectively analyzed its clinical outcomes and experiences, and explored the safety and effectiveness. From October 2003 to December 2008, 177 diffuse CAD patients with 229 vascular lesions received off-pump CABG plus CE. Incision was made at the hardest part of coronary artery and ≥ 2 cm from the distal intervention site. Then bypass graft was performed by internal mammary artery or saphenous vein. The intra-operative blood tests showed that 215 (93.9%) bridges were satisfied with (27 ± 12) ml/min blood flow while 14 bridges were dissatisfied. The blood flow was (7 ± 4) ml/min. Six (3.4%) cases suffered peri-operative myocardial infarction. Among them, 3 patients had no significant cardiac hemodynamic changes. Three suffered a low cardiac output and improved by intra-aortic balloon counter pulsation support. And they were then discharged after treatment. After 3 - 40 months, 98 patients underwent coronary angiography to measure the graft latency. And the blood flow was excellent. Off-pump CABG plus CE for diffuse coronary artery disease is both feasible and safe. And it is an effective treatment with a high degree of vascularization.

Effect of intra-aortic balloon pump support on microcirculation during high-risk percutaneous intervention

Intra-aortic balloon counter-pulsation (IABP) is recommended for hemodynamic support in cardiogenic shock. In addition, it can be applied during high-risk percutaneous interventions (PCI). While IABP support improves microflow in cardiogenic shock, its effect in hemodynamically stable patients is still unclear. We, therefore, sought to evaluate the effect of IABP treatment on microflow in hemodynamically stable patients undergoing elective high-risk PCI. In six patients with >50% left main stenosis, microflow was evaluated according to current guidelines, using side-stream dark-field microscopy, visualizing microcirculatory vessels without using fluorescent dyes. Microflow was analyzed separately for each vessel category (diameter: 10-25microm and 26-50microm), using a semiquantitative system (0= no flow; 1= intermittent flow; 2= sluggish flow; 3= continuous flow) by a trained investigator. Steady state recordings and additional recordings twenty seconds after discontinuation of the electively implanted IABP were acquired. Microflow in vessel categories 10-25microm and 26-50microm increased in this group of hemodynamically stable patients on use of IABP. Microflow decreased from 2.73 + or - 0.39 (p=0.052; 26-50microm: 2.88 + or - 0.20, p=0.008) to 2.22 + or - 0.23 (2.18 + or - 0.45) after stopping the IABP and increased to 2.90 + or - 0.14 (p=0.009; 2.85 + or - 0.28, p=0.009) after restart of the IABP. Circulatory support with IABP increases microcirculatory flow in the smallest vessels of the sublingual mucosa. Our data support the hypothesis that intra-aortic balloon counter-pulsation increases coronary and microvascular perfusion, thus, improving microcirculation even in hemodynamically stable patients. The use of IABP may increase safety of complex PCI and decrease the risk of deleterious complications.

The intra-aortic balloon pump in heart failure management: Implications for nursing practice

Management of acute heart failure is an important consideration in critical care. Mechanical support of the failing heart is crucial for improving health outcomes. The most common Australasian application of intra-aortic balloon counterpulsation (IABP) is in the setting of cardiogenic shock. High end users of IABP (>37/annum) demonstrate significantly lower mortality for cardiogenic shock managed with IABP (p<0.001) in contrast to hospitals which employ limited IABP (<4/annum). This underscores the importance of proficiency in managing the patient receiving IABP support. Nurses play a crucial role in caring for patients with acute heart failure. This paper summarises care considerations for management of the IABP.

Right Ventricular Failure Resulting from Pressure Overload: Role of Intra-Aortic Balloon Counterpulsation and Vasopressor Therapy

Augmentation of coronary perfusion may improve right ventricular (RV) failure following acute increases of RV afterload. We investigated whether intra-aortic balloon counterpulsation (IABP) can improve cardiac function by enhancing myocardial perfusion and reversing compromised biventricular interactions using a model of acute pressure overload. In 10 anesthetized pigs, RV failure was induced by pulmonary artery constriction and systemic hypertension strategies with IABP, phenylephrine (PE), or the combination of both were tested. Systemic and ventricular hemodynamics [cardiac index(CI), ventricular pressures, coronary driving pressures (CDP)] were measured and echocardiography was used to assess tricuspid valve regurgitation, septal positioning (eccentricity index (ECI)), and changes in ventricular and septal dimensions and function [myocardial performance index (MPI), peak longitudinal strain]. Pulmonary artery constriction resulted in doubling of RV systolic pressure (54 ± 4mm Hg), RV distension, severe TR (4+) with decreased RV function (strain: -33%; MPI: +56%), septal flattening (Wt%: -35%) and leftward septal shift (ECI:1.36), resulting in global hemodynamic deterioration (CI: -51%; SvO(2): -26%), and impaired CDP (-30%; P<0.05). IABP support alone failed to improve RV function despite higher CDP (+33%; P<0.05). Systemic hypertension by PE improved CDP (+70%), RV function (strain: +22%; MPI: -21%), septal positioning (ECI:1.12) and minimized TR, but LV dysfunction (strain: -25%; MPI: +31%) occurred after LV afterloading (P<0.05). With IABP, less PE (-41%) was needed to maintain hypertension and CDP was further augmented (+25%). IABP resulted in LV unloading and restored LV function, and increased CI (+46%) and SvO(2) (+29%; P<0.05). IABP with minimal vasopressors augments myocardial perfusion pressure and optimizes RV function after pressure-induced failure.

Acute microflow changes after stop and restart of intra-aortic balloon pump in cardiogenic shock

The intra-aortic balloon counter pulsation (IABP) is the most frequently used method of mechanical cardiac support in cardiogenic shock (CS). Microcirculatory impairment correlates with outcome in critically ill patients. We therefore investigated the acute influence of IABP therapy on sublingual microflow in patients with CS. Sidestream darkfield intravitalmicroscopy was used in 13 patients with severe CS. The sublingual microvascular bed (10-100 microm) was examined according to current guidelines. We measured microflow in means of microvascular flow index at baseline and after intentional stop of IABP support. A computerized model was used for blinded off-line analysis. Microflow in vessels 10-50 microm in diameter was improved during IABP support (P < 0.001). Norepinephrine had a negative effect on the response to IABP related microflow improvement. Cardiac Perfusion Index (product of Cardiac Power index and microflow) correlated best with blood lactate levels. It was the aim of this study to evaluate the acute influence of IABP therapy on microflow in vivo. In this setting we found that IABP therapy improves sublingual microflow. Future studies should investigate Cardiac Perfusion Index under such conditions with respect to clinical decision making.

Percutaneous coronary intervention with stenting of left main coronary artery with drug-eluting stent in the setting of acute ST elevation myocardial infarction

Aim Primary angioplasty of the left main coronary is not a common procedure. We present 16 cases of angioplasty of left main coronary artery with drug-eluting stent (DES) implantation in the setting of acute ST elevation myocardial infarction. Method Between December 2003 and November 2005, sixteen patients presented with acute ST elevation myocardial infarction where the left main coronary artery was shown to be involved with or without the left anterior descending or left circumflex arteries. Primary angioplasties were performed on the unprotected left main coronary artery. Five patients received direct stenting while the rest had pre-dilatation. Only one patient received Taxus® while the rest received Cypher® stents. Results Of the sixteen patients, eleven developed cardiogenic shock necessitating intra-venous inotropic and intra-aortic balloon counter-pulsation support. Seven perished in hospital (46%); four within the first day while one had a complicated course and perished on the 42nd day of hospitalization. There was no difference in clinical history (hypertension, diabetes, age, and previous coronary intervention) or hemodynamic features (presenting blood pressure, duration of infarct, stent length, and maximum balloon size or pressure) between the two groups. However, the use of inotropes and intra-aortic balloon counter-pulsation (100% vs. 44% p = 0.034) was significantly more common in the group which perished. Patient with cardiogenic shock had increased mortality of 63%. Of the nine survivors, one required repeat intervention for subacute stent thrombosis at sixteenth day and one underwent coronary bypass surgery at three months. All remained well up to mean follow up of 420 days. Conclusion Left main coronary artery infarct especially in the setting of cardiogenic shock has a very high mortality rate. Percutaneous intervention can be performed on these patients with minimal delay. In our series, we have shown that primary intervention of the unprotected left main coronary artery with a drug-eluting stent carries an acceptable level of major adverse coronary event. In those who survived the initial event, there is a low rate of mortality or morbidity.

Weaning intraaortic balloon counterpulsation: The evidence

The aim of this paper was to determine the most effective manner to wean intraaortic balloon counterpulsation (IABP) based on research evidence. An exhaustive search of the PubMed, Medline, CINAHL, Cochrane, Science Direct and Ovid databases was carried out to source relevant literature. The search revealed a paucity of literature related to the cessation of IABP. Evidence is unanimous in suggesting the minimization of pharmacological assistance before withdrawing any form of mechanical IABP. However, opinion related to the direct weaning of IABP by either volume reduction or frequency reduction is mixed. The assimilation of IABP studies would imply volume reduction weaning to be the most effective method of IABP support withdrawal. Volume reduction offers a more physiological approach in comparison to frequency reduction weaning, which fails to significantly differ from the complete cessation of IABP treatment. When initiating the withdrawal of any IABP support, volume reduction should be the method of choice.

A Simple Method of Triggering Balloon Counterpulsation Accurately During Off-Pump Coronary Artery Bypass Surgery

With increasing experience, off-pump coronary artery bypass grafting for high-risk patients can be performed safely. However, in patients who need intraaortic balloon counterpulsation support, mistriggering of intraaortic balloon counterpulsation during mobilization of the heart can induce unstable hemodynamic conditions. My colleagues and I have developed a simple method of detecting the trigger signal accurately: an epicardial pacemaker wire is placed close to the apex of the left ventricle, and 1 precordial V lead is disconnected and then linked to the epicardial pacemaker wire. This method provides an excellent detection of R-wave potentials in any position of the heart throughout an entire off-pump coronary artery bypass grafting procedure.

Alterations in ultrasonic backscatter during intra-aortic balloon counterpulsation support in patients with acute myocardial infarction

Alterations of ultrasonic backscatter parameters have been evident in humans with myocardial infarction or ischemia. The backscatter variability could be restored in ischemic or stunned myocardium after reperfusion. The aims of this study were to determinate changes in regional myocardial ultrasonic backscatter during intra-aortic balloon counterpulsation (IABP) support in patients with acute myocardial infarction (AMI), and to evaluate whether backscatter imaging could be a functional guide of IABP support. A total of 9 patients with AMI were investigated during IABP support with a two-dimensional (2-D) ultrasonic backscatter imaging approach for parasternal short-axis view. Coronary angiography was performed in 6 of the 9 patients. A total of 21 vessel territories were studied in different modes of IABP support: 1:1, 1:2 and standby. Restoration of cyclic variation of backscatter after IABP support was demonstrated in 10 vessel territories. Failure of restoration of cyclic variation of backscatter after IABP support was noted in 6 vessel territories with severe coronary lesions (total or nearly total occlusion) or scar tissue. No changes of the ultrasonic backscatter were found in nonischemic vessel territories with patent coronary arteries or TIMI III coronary flow. In addition, the wall motion score did not change significantly with different IABP support. These results suggest that IABP could restore the cyclic variation of backscatter in ischemic myocardium. Myocardial anisotropy may play an influential role in the alterations of ultrasonic backscatter. We propose that ultrasonic backscatter could be a noninvasively functional guide of IABP use in patients with AMI.

Coronary artery bypass grafting without cardiopulmonary bypass--initial experience of 50 cases.

This study was undertaken to assess our experience with the first 50 patients who underwent CABG without cardiopulmonary bypass. In seven patients left internal mammary artery to left anterior descending artery (LIMA-LAD) grafting was performed through a short left anterior thoracotomy. In 43 other patients median sternotomy was used. Primary CABG was performed in 48 patients; there were two reoperations. Eleven patients had unstable angina. Three patients had left ventricular ejection fraction (LVEF) equal to or lower than 25%. One patient had carcinoma of the right lung coexisting with unstable angina and underwent also right lower lobectomy. In each patient the clinical course, 12-lead ECG, transthoracic echocardiography and the serum levels of creatine kinase (CPK), alanine aminotransferase (ALAT), aspartate aminotransferase (AspAT) were assessed. The need for inotropic or intraaortic balloon counterpulsation (IABP) support and blood transfusion was also recorded. There were three deaths, all in the sternotomy group (6%). A patient with systemic lupus erythemetodes (SLE) died of postoperative MI due to graft thrombosis. Another patient who was found to have porcelain aorta and had LIMA-LAD grafting as a rescue procedure died of MI with low cardiac output. The third patient with unstable angina and ejection fraction of 30% developed postoperative MI with ventricular arrhythmia. One patient with LIMA-LAD graft in whom percutaneous translaminal coronary angioplasty (PTCA) had been abandoned because of coronary spasm developed acute myocardial ischaemia 5 h postoperatively. He had a vein graft placed to LAD in cardiopulmonary bypass, his further course was uneventful. Six patients had IABP support. Nine patients needed inotropic support. Ten patients received blood transfusion. Twelve-lead ECG did not show acute ischaemia or MI, apart from the above described cases. Echocardiographic check showed improved IVS contractility in three patients and better apex motion in one case. In the other survivors the echocardiographic findings were the same as before the procedure. ALAT and AspAT serum levels were normal in all the survivors, and the CPK levels did not exceed 200 IU/ml. One patient from the mini-thoracotomy group had recurrent angina 2 months after the procedure. His left internal mammary artery (LIMA) graft was occluded; we replaced it with a vein graft. All 47 survivors remain asymptomatic, with the mean follow-up time of 6 months. Coronary surgery without cardiopulmonary bypass seems a valuable alternative for high-risk patients.

Beat-to-beat Augmentation of Left Ventricular Function by Intraaortic Counterpulsation

Measuring the effects of intraaortic balloon counterpulsation (IABP) in single cardiac beats may permit an improved understanding of the physiologic mechanisms by which IABP improves the circulation. The objective of the study was to use trans- esophageal echocardiography in combination with hemodynamic measurements to test the hypothesis that IABP improves global left ventricular systolic function selectively in the IABP-augmented cardiac beats by acutely decreasing left ventricular afterload. Twenty-seven studies in which the IABP-to-R wave trigger ratio was serially changed from 1:1, 1:2, 1:4, 0:1 (IABP off) and back to 1:1 were performed in 20 anesthetized cardiac surgical patients during IABP support. Left ventricular short-axis end-diastolic cross-sectional area, end-systolic area, mean end-systolic wall thickness, and ejection time were measured by transesophageal echocardiography at the midpapillary muscle level. Aortic pressure was measured simultaneously from the central lumen of the intraaortic balloon catheter. These measurements were used to calculate the fractional area change, end-systolic meridional wall stress, and heart rate-corrected velocity of circumferential fiber shortening. The echocardiographic and hemodynamic parameters of left ventricular preload, afterload, and systolic function immediately after balloon deflation (IABP-augmented cardiac beats) were compared to the parameters measured during nonaugmented cardiac beats to determine the beat-to-beat effects of IABP on left ventricular function. IABP-augmented cardiac beats had a decreased systolic arterial pressure and end-systolic meridional wall stress and increased diastolic blood pressure, fractional area change, and velocity of circumferential fiber shortening compared to nonaugmented cardiac beats. IABP did not cause significant beat-to-beat changes in heart rate, pulmonary artery diastolic pressure, or central venous pressure. The improvement in left ventricular systolic function associated with IABP-augmented cardiac beats correlated with the decrease in end-systolic meridional wall stress for that cardiac beat. Beat-to-beat echocardiographic and hemodynamic measurements performed in anesthetized cardiac surgical patients during IABP support demonstrated improved left ventricular systolic function and decreased left ventricular systolic wall stress in the cardiac beats immediately after balloon deflation. The relationship between left ventricular systolic function and left ventricular systolic wall stress during IABP support suggests that afterload reduction was an important mechanism by which IABP instantaneously improved circulatory function in anesthetized cardiac surgical patients.

Intraaortic Balloon Counterpulsation Support in Cardiogenic Shock due to Ventricular Septal Perforation and Huge Inferior Myocardial Infarction

Intraaortic Balloon Counterpulsation Support in Cardiogenic Shock due to Ventricular Septal Perforation and Huge Inferior Myocardial Infarction