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PubMed1984

Exaggerated wave reflection in the kangaroo simulates arterial counterpulsation.

The ascending aortic pressure wave in kangaroos is quite different from that seen in other experimental animals and in humans, despite an ascending aortic flow wave that is virtually identical. The diastolic pressure surge in the ascending aortic pressure wave of kangaroos is very prominent--so much so that peak diastolic pressure is often greater than peak systolic pressure, with the pressure wave resembling that recorded in humans during intra-aortic balloon counterpulsation. Ascending aortic impedance patterns in kangaroos indicate the presence of a single functionally discrete reflecting site in the peripheral circulation, with high reflection coefficient. All findings--of pulse contour and impedance patterns--are explicable on the basis of arterial anatomy and body shape. Wave reflection from the distant, large, and vascular lower body appears to dominate the effects of wave reflection from the short, small, and less vascular head and forelimb system.

Animals↗

PubMed2003

Relation between hospital intra-aortic balloon counterpulsation volume and mortality in acute myocardial infarction complicated by cardiogenic shock.

BACKGROUND: Increasing evidence suggests an inverse relationship between outcome and the total number of invasive cardiac procedures performed at a given hospital. The purpose of the present study was to determine if a similar relationship exists between the number of intra-aortic balloon counterpulsation (IABP) procedures performed at a given hospital per year and the in-hospital mortality rate of patients with acute myocardial infarction complicated by cardiogenic shock. METHODS AND RESULTS: We analyzed data of 12 730 patients at 750 hospitals enrolled in the National Registry of Myocardial Infarction 2 from 1994 to 1998. The hospitals were divided into tertiles (low-, intermediate-, and high-IABP volume hospitals) according to the number of IABPs performed at the given hospital per year. The median number of IABPs performed per hospital per year was 3.4, 12.7, and 37.4 IABPs at low-, intermediate-, and high-volume hospitals, respectively. Of those patients who underwent IABP, there were only minor differences in baseline patient characteristics between the 3 groups. Crude mortality rate decreased with increasing IABP volume: 65.4%, lowest volume tertile; 54.1%, intermediate volume tertile; and 50.6%, highest volume tertile (P for trend <0.001). This mortality difference represented 150 fewer deaths per 1000 patients treated at the high IABP hospitals. In the multivariate analysis, high hospital IABP volume for patients with acute myocardial infarction was associated with lower mortality (OR=0.71, 95% CI=0.56 to 0.90), independent of baseline patient characteristics, hospital factors, treatment, and procedures such as PTCA. CONCLUSIONS: Among the myocardial infarction patients with cardiogenic shock who underwent IABP placement, mortality rate was significantly lower at high-IABP volume hospitals compared with low-IABP volume hospitals.

Acute Disease↗

PubMed1982

The effect of intraaortic balloon counterpulsation on regional myocardial blood flow and oxygen consumption in the presence of coronary artery stenosis in patients with unstable angina.

To determine whether a reduction in myocardial oxygen demand or an increase in coronary blood flow or both are responsible for the salutory effect of intraaortic balloon counterpulsation (IABP) in relieving medically refractory angina, we assessed these variables in six patients in whom IABP was required for relief of myocardial ischemia. IABP decreased the rate-pressure product and aortic end-diastolic pressure, and the peak systolic aortic pressure and regional myocardial oxygen consumption declined in all but one patient. Peak and mean aortic diastolic pressures increased. Changes in regional coronary blood flow paralleled changes in peak systolic aortic pressure (r = 0.92, p less than 0.007). Thus, relief of angina during IABP could not be ascribed to an increase in regional coronary blood flow. Reduction of myocardial oxygen consumption is the most likely mechanism by which IABP relieves myocardial ischemia in patients with unstable angina pectoris.

Aged↗

PubMed1983

Augmentation of regional coronary blood flow by intra-aortic balloon counterpulsation in patients with unstable angina.

Intra-aortic balloon counterpulsation is capable of reducing afterload in patients with unstable angina. Whether it is also capable of augmenting coronary blood flow to poststenotic myocardium is controversial. We studied seven patients receiving maximal drug therapy and requiring balloon pumping for unstable angina as balloon volume and assist ratio were altered. All patients had greater than 90% stenosis of the proximal left anterior descending coronary artery. With maximal augmentation (40 cc balloon volume, 1:1 assist ratio) great cardiac vein flow, representing the efflux from the left anterior descending coronary artery bed, rose from a baseline of 52 +/- 20 to 67 +/- 25 ml/min (mean +/- SD, p = .004) and mean aortic diastolic pressure increased from 77 +/- 13 to 99 +/- 33 mm Hg (p = .004). Increased great cardiac vein flow correlated with increased mean aortic diastolic pressure across changes in balloon volumes (off, 20 cc, 30 cc, and 40 cc) and changes in assist ratio (off, 1:4, 1:2, and 1:1) (p = .02). However, the intermediate balloon volumes produced great cardiac vein flows at an intermediate level between full assist and no assist (p less than .05), whereas the intermediate assist ratios did not augment flow. Thus balloon pumping increased flow to a bed fed by collateral vessels or critical stenoses; this increased flow correlated with increased aortic diastolic pressure, indicating probable loss of autoregulatory ability.

Aged↗

PubMed1994

Arterial diastolic pressure augmentation by intra-aortic balloon counterpulsation enhances the onset of coronary artery reperfusion by thrombolytic therapy.

BACKGROUND: The early establishment of infarct artery reperfusion by intravenous thrombolytic therapy has improved survival after acute myocardial infarction. Investigations of reperfusion have focused on the effects of specific thrombolytic agents, anticoagulation, and platelet inhibition. However, little attention has been given to the relation of arterial blood pressure to thrombolysis, a factor that probably affects thrombolytic agent delivery to the obstructing thrombus. METHODS AND RESULTS: The effect of arterial diastolic pressure augmentation by intra-aortic balloon counterpulsation (IABP) on reperfusion after intravenous thrombolytic therapy was studied in a canine model. A critical left anterior descending coronary artery stenosis was created by an occluder. Acute thrombosis immediately proximal to the occluder was formed by local injection of a blood and thrombin mixture into a segment of the artery that had intimal damage (groups 1 through 3). Continuous coronary blood flow velocity was measured by an epicardial Doppler probe. Group 1 (n = 7) served as control. Group 2 (n = 6) received an intravenous, front-loaded recombinant tissue-type plasminogen activator (rTPA) regimen (1.25 mg/kg total dose, 15% as bolus, 50% in the first 30 minutes, and 35% for the following 60 minutes). Group 3 (n = 6) received the same rTPA regimen with IABP beginning at the start of rTPA administration. Coronary blood flow velocity, arterial pressure, and heart rate were observed for 150 minutes after the start of thrombolytic therapy. Five animals did not undergo coronary thrombosis (group 4) and had coronary blood flow velocity determined before and after IABP at baseline and after creation of critical stenosis. Mean systolic arterial blood pressure and heart rate were not statistically different between groups. Peak augmented diastolic pressure by IABP was 97.9 +/- 1.3% of systolic pressure in group 3 dogs. Spontaneous reperfusion did not occur in any group 1 dogs. All animals treated with rTPA reperfused. Reperfusion occurred in group 3 (13.1 +/- 2.1 minutes) earlier than in group 2 (39.2 +/- 9.4 minutes, P = .02). Overall duration of arterial patency did not differ between group 2 (81.4 +/- 16.6 minutes) and group 3 (94.9 +/- 15.3 minutes, P = .52). Reocclusions occurred with similar frequency (P = .85) in groups 2 and 3. In group 4, IABP did not increase baseline coronary blood flow velocity. CONCLUSIONS: This study demonstrates that augmentation of diastolic arterial pressure by IABP enhances thrombolysis, leading to faster reperfusion. This effect appears to be unrelated to an increase in coronary blood flow and may be due to an effect of the augmented diastolic blood pressure wave on the obstructing thrombus. These findings suggest that the time to reperfusion by rTPA may be blood pressure dependent. The relation of arterial blood pressure to successful thrombolysis may have important implications for future treatment strategies for myocardial infarction.

Animals↗

PubMed1976

The influence of combined intra-aortic balloon counterpulsation and hyperosomotic mannitol on regional myocardial blood flow in ischemic myocardium in the dog.

We investigated the combined effectiveness of intra-aortic balloon counterpulsation and hyperosmotic mannitol (25%) on regional myocardial blood flow during acute coronary insufficiency. Cardiac output and paced heart rate were held constant in chloralose-anesthetized dogs during right heart bypass. Acute coronary insufficiency was produced by ligation of the proximal left anterior descending coronary artery (LAD). Regional myocardial blood flow was measured using radioactive microspheres. Left ventricular end-diastolic pressure, mean aortic pressure, maximum left ventricular dp/dt, and hematocrit were unchanged by combined mannitol infusion and balloon pumping. Studies of combined treatment with balloon pumping and mannitol immediately after the second of two 13-minute consecutive reversible ligations of the LAD demonstrated that (1) collateral coronary blood flow increased 46% (P less than 0.02) in ischemic myocardium compared with mannitol infusion along during the first LAD ligation, and (2) collateral coronary blood flow increased 27% (P less than 0.05) in ischemic myocardium compared with balloon pumping along during the first LAD ligation. Studies in which combined treatment was delayed until 20 minutes after LAD ligation demonstrated that collateral coronary blood flow was elevated by 33% (P les than 0.05) in ischemic myocardium compared to control studies in which balloon pumping alone had no effect. The results suggest that the increase in collateral coronary blood flow was in part a result of an increased transmural pressure gradient produced by balloon diastolic augmentation and the ability of mannitol to reduce coronary vascular resistance in ischemic myocardium.

Animals↗

PubMed1971

The effects of intra-aortic counterpulsation on cardiac performance and metabolism in shock associated with acute myocardial infarction.

The effect of intra-aortic counterpulsation (IACP, 22-94 hr) on hemodynamics and cardiac energetics was evaluated in 10 patients in shock after acute myocardial infarction. The data clearly indicate that IACP improves myocardial oxygenation, enhances peripheral perfusion, and probably improves myocardial contractility in the severely diseased heart. Before treatment, decreases in cardiac index (mean value, 1.22 liter/min per m(2)), systolic ejection rate (67 ml/sec), and time-tension index per minute (1280 mm Hg.sec/min) were observed. Systemic vascular resistance varied widely. Low coronary blood flow (68 ml/min per 100 g) was associated with increased myocardial oxygen extraction (79%), low coronary sinus oxygen tension (20 mm Hg), and abnormal myocardial lactate-pyruvate metabolism. During 4-6 hr of IACP, systolic pressure and left ventricular outflow resistance decreased by 18% and 24%, respectively, while cardiac index improved by 38%. Diastolic arterial pressure rose 98%. Increase in coronary blood flow from an average of 68 to 91 ml/100 g per min (P < 0.001) was significantly correlated with rise in mean arterial pressure (r = 0.685). This correlation was best expressed in a third-order curve, which intercepts the point of no flow at a mean aortic pressure of 30 mm Hg. The flow-pressure curve is relatively flat above 65-70 mm Hg, but becomes steeper as mean aortic pressure falls below this point. Myocardial oxygen consumption remained essentially unchanged during early IACP and tended to rise during the later stages. However, the relationship of cardiac work performed to oxygen availability was markedly improved. Myocardial lactate production of 6% shifted to 15% extraction (P < 0.001). After termination of IACP, hemodynamics and myocardial perfusion and metabolism remained improved in the four patients who could be reevaluated. Although the acute shock state was reversed in all patients, only one left the hospital. Extensive myocardial damage limits the long-term survival of such patients. Therefore early IACP seems desirable, when subtle evidence of pump failure after acute myocardial infarction occurs. Early use of IACP may prevent the development of severe coronary shock or may stabilize cardiac energetics in severe shock facilitating subsequent surgical intervention.

Aged↗

PubMed1999

Concomitant use of intraaortic balloon counterpulsation and streptokinase in acute anterior myocardial infarction.

Using a prospective, nonrandomized design, the authors sought to determine whether concomitant use of intraaortic balloon counterpulsation (IABP) and streptokinase in acute anterior myocardial infarction (MI) would improve the in-hospital mortality rate and angiographic findings. The study included 45 patients with an acute anterior MI. All patients received intravenous streptokinase. Among these, 25 patients had concomitant IABP while the remaining 20 patients had streptokinase alone. All patients underwent cardiac catheterization. Patients treated with concomitant IABP had a significantly higher frequency of thrombolysis in myocardial infarction (TIMI) grade 3 flow (n: 11; 44% vs n: 1; 5%, p<0.05), and there was a trend toward a lower in-hospital mortality rate in the IABP group (n: 0; 0% vs n: 3; 15%, p=0.08). The angiographic presence of thrombus image and grade > or =2 coronary collateral circulation to the infarct-related coronary artery for the IABP and non-IABP groups did not differ significantly. The preliminary results of this study suggest that concomitant use of IABP and streptokinase in acute anterior MI increases the incidence of TIMI grade 3 flow and may have decreased the in-hospital mortality rate without unacceptable rates of vascular or hemorrhagic complications.

Cardiac Catheterization↗

PubMed2004

Survival of patients treated with intra-aortic balloon counterpulsation at a tertiary care center in Pakistan - patient characteristics and predictors of in-hospital mortality.

BACKGROUND: Intra-aortic balloon counterpulsation (IABC) has an established role in the treatment of patients presenting with critical cardiac illnesses, including cardiogenic shock, refractory ischemia and for prophylaxis and treatment of complications of percutaneous coronary interventions (PCI). Patients requiring IABC represent a high-risk subset with an expected high mortality. There are virtually no data on usage patterns as well as outcomes of patients in the Indo-Pakistan subcontinent who require IABC. This is the first report on a sizeable experience with IABC from Pakistan. METHODS: Hospital charts of 95 patients (mean age 58.8 (+/- 10.4) years; 78.9% male) undergoing IABC between 2000-2002 were reviewed. Logistic regression was used to determine univariate and multivariate predictors of in-hospital mortality. RESULTS: The most frequent indications for IABC were cardiogenic shock (48.4%) and refractory ischemia (24.2%). Revascularization (surgical or PCI) was performed in 74 patients (77.9%). The overall in-hospital mortality rate was 34.7%. Univariate predictors of in-hospital mortality included (odds ratio [95% CI]) age (OR 1.06 [1.01-1.11] for every year increase in age); diabetes (OR 3.68 [1.51-8.92]) and cardiogenic shock at presentation (OR 4.85 [1.92-12.2]). Furthermore, prior CABG (OR 0.12 [0.04-0.34]), and in-hospital revascularization (OR 0.05 [0.01-0.189]) was protective against mortality. In the multivariate analysis, independent predictors of in-hospital mortality were age (OR 1.13 [1.05-1.22] for every year increase in age); diabetes (OR 6.35 [1.61-24.97]) and cardiogenic shock at presentation (OR 10.0 [2.33-42.95]). Again, revascularization during hospitalization (OR 0.02 [0.003-0.12]) conferred a protective effect. The overall complication rate was low (8.5%). CONCLUSIONS: Patients requiring IABC represent a high-risk group with substantial in-hospital mortality. Despite this high mortality, over two-thirds of patients do leave the hospital alive, suggesting that IABC is a feasible therapeutic device, even in a developing country.

Aged↗

PubMed2005

Usefulness of unipolar epicardial ventricular electrogram for triggering of intraaortic balloon counterpulsation during off-pump coronary artery bypass surgery in patients with hemodynamic instability complicating acute coronary syndromes.

During off-pump coronary artery bypass graft (CABG) surgery for patients requiring preoperative intraaortic balloon counterpulsation (IABP) support, errors in timing of IABP during mobilization of the heart can induce unstable hemodynamic conditions. We applied a simple technique for triggering IABP accurately during off-pump CABG: one end of an epicardial pacemaker wire is placed on the surface of the left ventricle, and the other end is linked to one of the precordial V leads. This technique provided an exact detection of R-wave potentials in any position of the heart during the off-pump CABG procedure. Ten patients with hemodynamic instability complicating acute coronary syndromes underwent off-pump CABG with this technique, including grafting to the circumflex system, safely and successfully.

Acute Disease↗

PubMed1995

Intra-aortic balloon counterpulsation augments cerebral blood flow in a canine model of subarachnoid hemorrhage-induced cerebral vasospasm.

We tested the effect of intra-aortic balloon counterpulsation (IABC) on cerebral blood flow (CBF) in a canine model of cerebral vasospasm. Cerebral vasospasm was induced in ten adult mongrel dogs using a "two-hemorrhage" model. CBF was then measured using radiolabeled microspheres, before and after activation of an intra-aortic balloon pump. Physiologic parameters including pCO2 and cardiac filling pressures were maintained constant during the experiment. Cardiac output was monitored in each animal. CBF increased with IABC in all ten animals. The mean CBF was 78.5 milliliters per 100 grams per minute (ml/100g/min) before versus 93.3ml/100g/min after IABC (P = 0.0001). Increases in CBF were associated in most, but not all, cases with increases in cardiac output. This study supports the ability of IABC to raise CBF in the setting of cerebral vasospasm. IABC may represent an important clinical option in cases of refractory vasospasm following aneurysmal subarachnoid hemorrhage.

Animals↗

PubMed1981

Intraaortic balloon counterpulsation in a community hospital.

Our experience with intraaortic balloon counterpulsation in 41 patients documents the feasibility of a coordinated aggressive therapeutic approach in patients with potentially fatal complications of coronary artery disease. The use of intraaortic balloon pump in a non-cardiac surgical center has allowed hemodynamic support in the critically ill, safety in angiography, appropriate selection of patients for surgery, and safe transportation to a cardiac surgery center when indicated.

Adult↗

PubMed1982

Percutaneous intraaortic balloon counterpulsation. Clinical effectiveness and hazards.

Because of its greater ease and rapidity of insertion, the percutaneous intraaortic balloon in many institutions has become the primary method for implementing counterpulsation. We report the results and complications of 113 attempted procedures in a variety of clinical settings. We had a high (93.8 percent) insertion success rate. However, our 18.6 complication rate was similar to the experience reported for the surgical method of insertion. Thus, the original anticipation of reduced complications with this method has not been realized in this and other recent reports.

Adult↗

PubMed2000

Complications associated with percutaneous placement of intra-aortic balloon counterpulsation: can unsheathed insertion reduce limb ischaemia?

Complications related to percutaneous placement of intra-aortic balloon pump counterpulsation are still high despite major refinements in catheter design and techniques. One hundred and forty-eight patients in whom intra-aortic balloon pumping was inserted were classified into two groups on the basis of the insertion technique. Group I included 103 patients in whom the conventional percutaneous insertion was used. A sheathless insertion technique was used in group II (n = 45). The overall complication rate was 16.6% (25 of 150), in which lower limb ischaemia was the most common complication. The limb ischaemia was noted in 12 patients (11.5%) in group I and 4 patients (8.9%) in group II (statistically not significant). Peripheral vascular disease, diabetes mellitus and female gender were found to be significant predictors of limb ischaemia (p = 0.01, p = 0.02 and p = 0.03, respectively). In conclusion, sheathless insertion of intra-aortic balloon pump catheters does not reduce the incidence of limb ischaemia.

Adult↗

PubMed1977

Intraaortic counterpulsation balloon: radiographic considerations.

The intraaortic counterpulsation balloon is being used with increasing frequency in the setting of cardiogenic shock and/or high risk cardiac surgery. The radiologist should be aware of the normal function of this cardiac assist device, as well as its potential complications. The principal complications apparent on the plain chest radiograph are related to improper positioning of the balloon catheter.

Aortic Aneurysm↗

PubMed1989

Intra-aortic balloon counterpulsation with special reference to determinants of survival.

From 1981 through 1985 intra-aortic balloon counterpulsation (IABP) was required by 90 patients on a total of 91 occasions. They included 85 (3.1%) of the 2751 patients undergoing open-heart surgery during that time. IABP was used preoperatively in 13 cases, to assist weaning from cardiopulmonary bypass in 64, postoperatively in nine, and without cardiac surgery in five cases. Complications arose from IABP in 24/90 patients (27%). The overall short-term survival rate following IABP was 61%, and the long-term (mean 23 months) rate was 51%. Early recovery of cardiac function was the main determinant of survival. Female sex, renal failure and postinfarction ventricular septal defect and mitral incompetence were over-represented among the nonsurvivors. IABP therefore is useful in reversible left ventricular dysfunction, whereas inadequate perfusion of vital organs with potential for failure of more than one organ system implies diminished likelihood of survival.

Aged↗

PubMed1993

Total parenteral nutrition in patients with intra-aortic balloon counterpulsation.

The effects of total parenteral nutrition (TPN) were studied in nine of 19 patients with intra-aortic balloon pumping TPN (c. 27 kcal/kg/day) was begun 3 hours after the start of pumping. The non-protein caloric source was composed of hypertonic dextrose and fat emulsion (60% and 40%). The nitrogen intake was 1 g/150-200 kcal/day. The ten control patients received 5% dextrose in corresponding volume/hour. Hemodynamic studies were performed before and 24, 48 and 72 hours after the start of counterpulsation. The predicted and the observed resting energy expenditure were recorded in both patient groups during counter-pulsation. Systemic and pulmonary vascular resistance differed significantly between the groups. Cardiac function improved in both groups. In the TPN group the measured resting energy expenditure increased by 33% more than predicted on day 2 and by 56% on day 3 and in the controls the figures were 31% and 40%--all rises significant. Total parenteral nutrition with low fat content thus alters the hemodynamic equilibrium without clinically significant effects in patients undergoing intra-aortic balloon pumping. These patients are hypermetabolic and should receive artificial nutrition as soon as possible.

Coronary Artery Bypass↗

PubMed1976

Support of the myocardium with intra-aortic balloon counterpulsation following cardiopulmonary bypass.

Intra-aortic balloon counterpulsation (IABC) was instituted in 27 patients in cardiogenic shock who had undergone cardiopulmonary bypass (CPB). Patients who required IABC either prior to CPB or else to be weaned from CPB had a survival rate of 22 per cent (2/9). In contrast, the survival rate for those patients requiring IABC after CPB had been discontinued was 72 per cent (13/18). The composition of these two groups was different. The first group contained primarily patients with either severe coronary artery disease or aortic valve stenosis, whereas the latter group contained patients with either less severe coronary artery disease or mitral valve disease. Most patients had an initial satisfactory response to IABC. The over-all survival rate was 55 per cent (15/27). IABC was particularly beneficial for those patients in cardiogenic shock following CPB who had not had massive and irreveraible myocardial injury.

Adult↗