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PubMed1978

[Effect of intra-aortic balloon counterpulsation on regional blood circulation].

The effect of intra-aortic balloon counterpulsation (IABC) on the volume blood flow in the descending branch of the left coronary artery and in the vertebral, renal, and femoral arteries was studied in dog experiments by means of an electromagnetic flowmeter. Resistography was applied to appraise the regulatory changes in the resistance to the blood flow in the vascular regions mentioned during IABC. It is shown that the increase in the coronary and cerebral blood flow during IABC is not associated with the reflex dilation of the resistant vessels of the heart and brain and is mainly due to a rise of diastolic pressure in the aorta. The volume blood flow in the kidney and hind extremity is maintained during IABC at a level close to the initial level due to regulatory decrease of the resistance of the vessels of these organs.

Animals↗
PubMed1978

Intra-aortic balloon pumping: theory and practice. Experience with 325 patients.

Intra-aortic balloon pumping to support the failing circulation is now an accepted therapeutic modality. The device is simple. Insertion can be accomplished rapidly and efficiently in emergency rooms, coronary care units, cardiac catheterization suites and operating rooms, preoperatively, intraoperatively and postoperatively. The hemodynamic effects are immediate and predictable, and the accruing clinical results show increasing survival and hospital discharge rates. In these institutions, mechanical support of the circulation by this and more advanced methods has been formalized within the responsibility of a Circulatory Support Service. The purpose of this report is to summarize some observations and analyses which have been made during care of 325 consecutive postcardiotomy and/or postinfarction cardiogenic shock patients. Historical, theoretical, basic, and applied aspects and current results are included. Foremost are the straightforward concepts of considering the heart as a pump, the failing heart as a failing pump and intra-aortic balloon pumping as a temporary intravascular, auxiliary pump, capable of stabilizing or reversing that failure if utilized early in its evolution.

Adult↗
PubMedDate not supplied

Heart transplantation in patients requiring preoperative mechanical support.

Since January 1985, the members of the Heart Transplant Program at Washington University Medical Center, St. Louis, have performed 53 transplants in 50 patients. Thirteen patients have required preoperative mechanical support. These patients ranged in age from 32 to 58 years, with a mean of 47 years. Seven patients had undergone a total of 12 prior cardiac surgical procedures. Preoperative diagnosis was coronary artery disease in nine patients, cardiomyopathy in three, and valvular heart disease in one. Two patients had mechanical ventilatory support before operation. Five patients required preoperative intraaortic balloon counterpulsation (IABP). Five patients required left ventricular assistance with the Bio-Medicus centrifugal pump (Bio-Medicus Inc., Eden Prairie, Minnesota). Two of these patients had the left ventricular assist device (LVAD) inserted at the end of a failed cardiac procedure. One patient required the extracorporeal membrane oxygenator (ECMO) for right ventricular decompensation and cardiac arrest 4 hours after a seemingly successful orthotopic transplantation. Twelve of the 13 patients (92%) who required mechanical assistance of circulation and/or respiration before operation underwent a successful transplant. One patient who had IABP support perioperatively did not survive surgery. All patients who had a bridge to transplantation with the LVAD and the one patient with a bridge to transplant with ECMO are long-term survivors of transplantation. There has been one late death from cardiac causes in a patient who had IABP support before operation; the death was presumed to be from acute rejection, though this could not be documented at autopsy. Actuarial survival in this group is 82% at 12 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1981

Hemodynamic regulation in total artificial heart recipients.

The right and left atrial pressures (RAP and LAP), circulating blood volume (CBV) and pump output were analyzed in 17 calves implanted with a free-diaphragm-type total artificial heart. A high RAP and increased CBV were common features in these animals, while the LAP was maintained in a nearly normal range throughout the course. Some correlation was seen between RAP, CBV and pump output, which was maintained in the range of 86.6 to 130.1 ml/min/kg. In the atrial myocardium various morphological changes were observed accompanied by thickening of the cell, which was conspicuous after one month of implantation. To improve this high venous pressure problem, an automatic controller for pusher-plate-type pumps wtih a greater sensitivity was introduced. A preliminary in vivo study using this new system is also reported.

Animals↗
PubMed1975

The use of the TDMAC-heparin shunt in replacement of the descending thoracic aorta.

The use of a flexible polyvinyl tube bonded with tridodecylmethylammonium-heparin (Gott) as a temporary shunt during the resection of lesions of the descending thoracic aorta has proven a safe and simple means of providing adequate circulation to the abdominal viscera and spinal cord. This technique avoids the metabolic consequences of ischemia to the lower body, diminishes left ventricular afterload during aortic clamping, and obviates the requirement for systemic anticoagulation associated with pump bypass. Between September 1970 and October 1974, 24 patients have been operated using the TDMAC shunt. There were two deaths (9%) among the 22 patients undergoing elective resections. Two patients with acutely dissecting and ruptured aneurysms expired. Followup data has been obtained on all patients from one to 46 months postoperative. The ease with which the shunt is inserted and its adaptability to varied clinical and anatomic situations is stressed. We feel that TDMAC-Heparin shunt provides the best method of circulatory support for elective operative procedures on the descending thoracic aorta.

Adult↗
PubMed1994

The effects of dynamic cardiac compression on ventricular mechanics and energetics. Role of ventricular size and contractility.

The purpose of this study was to determine the role of ventricular size or contractility in the effectiveness of dynamic cardiac compression in terms of the pressure-volume relationship and myocardial oxygen consumption. In 10 isolated cross-circulated dog hearts, the ventricle was directly compressed during systole. For the volume run, measurements for slope of the end-systolic pressure-volume relation, pressure-volume area, external work, coronary blood flow, and myocardial oxygen consumption were achieved before and during a fixed amount of dynamic cardiac compression. Left ventricular volume was then increased while stroke volume was kept constant, and measurements were repeated. For the contractility run, after the control measurements were taken, left ventricular contractility was significantly increased or decreased by infusion of either dobutamine or propranolol into the coronary circulation. Measurements were repeated before and during dynamic cardiac compression at the control level of end-diastolic and stroke volumes. Dynamic cardiac compression significantly increased slope of the end-systolic pressure-volume relation, pressure-volume area, and external work (p < 0.01), whereas coronary blood flow and myocardial oxygen consumption were not affected. The increase in pressure-volume area caused by dynamic cardiac compression was greater with the larger volume. Despite the significant differences in the native left ventricular contractility, the increases in slope of the end-systolic pressure-volume relation, pressure-volume area, and external work did not differ among the three groups. We conclude that dynamic cardiac compression enhances left ventricular systolic function independent of ventricular contractility and without affecting coronary blood flow or myocardial oxygen consumption. Mechanical enhancement is more effective in the dilated heart.

Animals↗
PubMed1981

Intra-aortic balloon counterpulsation: rationale, application and results.

Intra-aortic balloon counterpulsation is an effective means of reducing myocardial ischemia and supporting the failing circulation. Its therapeutic benefits are the direct result of distolic augmentation and systolic unloading, the former increasing myocardial perfusion and the latter enhancing cardiac performance. Indirect effect include diminution of ischemia by decrease in the determinants of myocardial oxygen demand and improved ventricular function secondary to the decreased ischemia. Intra-aortic balloon counterpulsation is indicated in clinical syndromes related to intractable cardiac ischemia, including myocardial infarction shock and severe left ventricular failure, refractory ischemic pains, and ventricular arrhythmias unresponsive to medical management. It is also of importance in other situations associated with low cardiac output. This therapeutic modality has recently been considered for early use in extensive myocardial infarction to limit cardiac damage and avert complications. Recent technical advances have facilitated the ease and safety of application of intra-aorta balloon counterpulsation. Complication are of low frequency but can be serious and employment of the method is predicated upon consideration of both potential benefits and risks.

Acute Disease↗
PubMed1976

Isosorbide dinitrate and intra-aortic balloon pumping in preinfarctional angina. Effects on central circulatory dynamics.

The dynamics of the central circulation were measured by a radionuclidic technique in 18 men with high-risk preinfarctional angina who received therapy with isosorbide dinitrate (n equals 18), intra-aortic balloon pumping (n equals 8), or both (n equals 8). Administration of 5 mg of isosorbide dinitrate sublinqually was associated with a reduction in stroke volume index (SVI), cardiac index (CI), systemic arterial blood pressure, and left ventricular end-diastolic volume (LVEDV) and with increased left ventricular ejection fraction (LVEF). Intra-aortic balloon pumping did not alter SVI or CI, but decreased systolic blood pressure and LVEDV and increased LVEF and diastolic blood pressure. The combination of therapy with isosorbide dinitrate and intraaortic balloon pumping resulted in decreased SVI, systolic blood pressure, and LVEDV and increased LVEF. Thus, therapy with isosorbide dinitrate reduced left ventricular preload, and intra-aortic balloon pumping reduced blood pressure, which resulted in a decreased LVEDV and an increase in LVEF. Therapy with isosorbide dinitrate and intra-aortic balloon pumping act to alter central circulatory dynamics in favor of reducing myocardial oxygen demand.

Adult↗
PubMed2002

An experimental study of vascular dynamics by an acceleration plethysmogram using artificial circulation devices.

Plethysmogram has been widely known as a conventional non-invasive simple method to obtain information on peripheral circulatory kinetics. We made a quantitative assessment of the relationships between the various circulatory parameters, using the simple conventional measurement method of treating acceleration plethysmograms (the second derivatives of digital plethysmograms) as indicators of peripheral circulation kinetics. We designed a prototype model peripheral circulatory circuit, using an artificial heart, for the purpose of clarifying the relationship between physical factors and plethysmograms. In our models of the peripheral circulatory system, we made use of various types of matching silicon tubes, as well as canine carotid arteries, as substitutes for human arteries. We evaluated the mechanical characteristics, such as the pressure and volume characteristics of the silicon tubes and canine carotid arteries. Plethysmogram alterations were measured using a photoelectric digital plethysmogram. When we examined the acceleration plethysmogram b/a values, which indicate blood vessel extensibility and hardness, and the d/a values, which we were able to use as an index of peripheral circulatory kinetics, it was clear from out model testing that canine carotid arteries displayed b/a values that were closest to those found in the human fingertip; among artificial tubes, the closest was a tube with a diameter of 4 mm (0.18 mm in thickness). The b/a values of all types of tubes declined when the compliance of the arterial system was increased, and it was confirmed through model testing that b/a values are an indicator of blood vessel extensibility.

Assisted Circulation↗
PubMed1990

[Experimental study on right ventricular function during left heart bypass--in a coronary septal branch ligation model].

Right heart failure (RHF) during left heart bypass (LHB) has been recognized clinically. Two hypotheses concerning RHF during LHB exist: one suggests that the cause is related to LHB itself, and another suggests that RHF existed prior to LHB. By using 16 mongrel dogs, the influence of LHB and ventricular septal ischemia on the right heart was studied experimentally. Under the extracorporeal circulation the coronary septal branch was dissected and a suture was hooked around the artery for the ligation. To maintain a constant right ventricular (RV) preload at 100 ml/kg/min, blood was drained from both the superior and inferior venae cavae, and was sent to the right atrium (RA) by a roller pump. Functional parameters of right heart, such as RA pressure, RV pressure, the first derivative of RV (RV dp/dt) and RV free wall contractile width, were measured while the LHB between left atrium and femoral artery was established. The measurements were done before and after the ligation of the septal branch, and were also done during LHB when the LHB ratio was changed from 0, 40, 60, 80, 100, 100, 80, 60, 40 and 0% of RV preload. RV free wall contractile width, measured by ultrasonic method, and the Max RV dp/dt were decreased significantly when LHB ratio was increased and both were increased when LHB ratio was decreased. When the septal branch was ligated, the contractile width was decreased significantly. The max RV dp/dt was also decreased but not significantly. When the LHB was performed after ventricular septal branch ligation, the trend of the RV functional changes was similar to that before ligation.

Animals↗
PubMed1984

Mechanical control of circulation: clinical results with intra-aortic balloon pumping and veno-arterial bypass in left and/or right cardiac failure.

Eighty-seven cases were studied in which IABP was used with open heart surgery, and 19 in which V-A bypass was employed. IABP was used in 31 patients with ischemic heart disease, which had the best survival rate (52%). Recent experience shows that the effects of IABP increase the operability of certain high-risk patients with severely impaired left ventricular function. In valvular heart disease, IABP was used with a survival rate of 34%. In congenital heart disease, the IABP survival rate was the worst among the groups studied because, in addition to left heart failure, many other factors also as cause the low cardiac output syndrome during corrective surgery for complicated cardiac anomalies. In total right heart bypass, or Fontan's procedure, three out of five cases were weaned from IABP; one of them is still alive. IABP was used with success in one case of valvular heart disease with almost no contraction of the right ventricle after repair. Therefore, IABP could be expected to improve the condition of severe postoperative right heart failure, or the equivalent condition, when there is subnormal left ventricular function in the postoperative period and pulmonary vascular resistance is normal. There has been only one successful V-A bypass lasting 11 hours, in valvular heart disease, and another case, in congenital heart disease, where the patient was weaned after V-A bypass lasting four days.

Aged↗
PubMed1991

Skeletal muscle powered ventricle: comparison of double-layered small ventricle and single-layered large ventricle.

Canine left latissimus dorsi (LD) muscles were used to construct two kinds of skeletal muscle powered ventricles (SMPV): a double layered small size (10-17 mL) SMPV (A), and a single-layered large size (40-70 mL) SMPV (B). The same muscle was used sequentially for the construction of both SMPV. A mock circulation system was used for testing. This allowed for change of the preload (10-60 mmHg) and afterload (40-160 mmHg) independently. The peak developed pressure (PDP) and stroke volume (SV) were measured, and the stroke work (SW) was analyzed on line by a computer. The isovolumic PDP was 93.3 +/- 11.8 mmHg at 10 mmHg preload, and 157.7 +/- 20.2 mmHg at 60 mmHg for A, and 37.8 +/- 5.5 mHg and 107.8 +/- 8.5 mmHg for B. The SV and SW at 50 mmHg preload and 80 mmHg afterload were 18.30 +/- 1.25 mL and 1.06 +/- 0.10 x 10(6) erg for A, and 34.18 +/- 2.36 mL and 2.51 +/- 0.28 x 10(6) erg for B. The SV and SW at 20 mmHg preload and 160 mmHg afterload were 2.65 +/- 0.31 mL and 0.27 +/- 0.05 x 10(6) erg for A, and 1.03 +/- 0.23 mL and 0.04 +/- 0.01 x 10(6) erg for (B). The SW generated by the large single-layered SMPV is similar to that reported for the canine left ventricle but requires a high preload. The large single-layered SMPV showed a higher dependence on pre- and afterload changes than the double layered small SMPV, which generates a higher pressure even at low preloads.

Animals↗
PubMed1990

Platelet function in cardiopulmonary bypass and artificial organs.

Extensive contact between blood and synthetic surfaces is associated with both quantitative and qualitative changes in platelet function. Cardiopulmonary bypass is associated with a decline in the circulating platelet count, release of platelet alpha granules and possibly platelet dense and lysosomal granule release, and a prolongation of the bleeding time. It is assumed that these platelet alterations contribute to postoperative blood loss and reoperation for bleeding. Improvements in technology have reduced but not eliminated the adverse platelet changes. Temporary inhibition of platelet function during surface contact has achieved additional improvement in the setting of heparin-induced thrombocytopenia but is not yet suitable for "routine" open heart surgery. Long-term cardiopulmonary bypass or extracorporeal circulation membrane oxygenation is receiving increased use during acute respiratory insufficiency. Systemic anticoagulation is required. Bleeding and platelet consumption continue as clinical problems and are treated by repeated platelet transfusion. Because no air interface is present in this setting and the synthetic surface is homogeneous this would appear to be the ideal area for application of platelet functional inhibition and synthetic surface passivation to reduce platelet consumption. Although still under review by the Food and Drug Administration, pulsatile devices, including the total artificial heart, increasingly are being used to provide temporary support for the failing heart. Furthermore, it is likely that totally implantable devices will become available in the very near future. Considering that thromboembolism is a major problem for recipients of mechanical valves, it is likely that thromboembolism will persist as a limiting factor in the further implementation of pulsatile devices. It is assumed that imaginative antithrombotic therapy will be required and that platelet activation will be fundamental to the thrombotic process. Platelet behavior in this setting, however, remains incompletely characterized. The analytical methodology that has been used to assess platelet behavior during cardiopulmonary bypass should be applied to the pulsatile devices as well and results correlated with clinical problems. This should permit standardization of antithrombotic therapy and rational use of platelet functional inhibition.

Assisted Circulation↗
PubMed1997

Dynamic cardiac compression improves contractile efficiency of the heart.

The effect of dynamic cardiac compression on left ventricular contractile efficiency was assessed in terms of the pressure-volume relationship and myocardial oxygen consumption. In 11 excised cross-circulated dog hearts, the ventricle was directly compressed during systole (dynamic cardiac compression). Measurements for pressure-volume area (a measure of total mechanical energy), external work, and myocardial oxygen consumption were done before and during dynamic cardiac compression. Dynamic cardiac compression increased pressure-volume area by 28% +/- 17% (mean plus or minus the standard deviation) and external work by 24% +/- 20% (p = 0.0000185 and 0.0000212, respectively) at given end-diastolic and stroke volumes without affecting myocardial oxygen consumption. As a result, the oxygen cost of pressure-volume area, that is, the slope of the myocardial oxygen consumption-pressure-volume area relationship, significantly decreased by 16% +/- 13% (p = 0.0000135) whereas the pressure-volume area-independent myocardial oxygen consumption was unchanged. Then, contractile efficiency, that is, the reciprocal of the slope of the myocardial oxygen consumption-pressure-volume area relationship in joules significantly improved from 45% +/- 8% to 53% +/- 13% (p = 0.0000437). When the native myocardial oxygen consumption-pressure-volume area relationship was assessed by subtracting the dynamic cardiac compression pressure applied to the heart, the slope of the myocardial oxygen comsumption-pressure-volume area relationship returned to the control level. This indicates that the contractile efficiency of the native heart was not affected by dynamic cardiac compression. We conclude that dynamic cardiac compression enhances left ventricular pump function by improving the contractile efficiency of the overall heart leaving the energetics of the native heart unchanged.

Animals↗
PubMedDate not supplied

Dynamic cardiomyoplasty in patients.

Dynamic cardiomyoplasty has been used to correct cardiac defects, augment contraction of weakened myocardium, and support circulation of end-stage heart disease patients by using their own skeletal muscle after electric conditioning. Five patients, each with a history of myocardial infarction and diffused coronary artery disease, underwent the application of the left latissimus dorsi muscle over the anterolateral wall or around the ventricles. In all patients the left latissimus dorsi muscle was dissected free from all insertions with careful preservation of the thoracodorsal nerve and vessels. The freed muscle flap was internalized into the thoracic cavity with the humeral tendinous end of the muscle sutured to the periosteum of the second or third rib after subperiosteum resection of a portion of the rib. The muscle flap was used in three of the five patients for ventricular wall repair after aneurysmectomy. In the other two patients the muscle was applied over the ventricles for functional augmentation. The skeletal muscle was electrically conditioned to contain mainly fatigue-resistant muscle fibers and was stimulated to contract synchronously with the heart. All patients survived the operation, with immediate improvement of ventricular function for those who had had aneurysmectomy. A significant increase in ejection fraction was observed in three of the five patients when the pacemaker was turned on. One patient died of sudden ventricular arrhythmia 2 months after the operation. The last patient is doing well at 6 weeks after operation. The first patient has been followed up for more than 3 years and continues to do well.(ABSTRACT TRUNCATED AT 250 WORDS)

Assisted Circulation↗
PubMed1984

Circulation control of experimental and clinical profound left ventricular failures by automatic left ventricular assist system.

It is desirable that circulation control of the patient using a left ventricular assist device (LVAD) should be achieved appropriately and safely. We have developed an automatic LVAD system, which can maintain the normal circulation irrespective of the severity of heart failure and can restore the failing heart by decreasing the bypass flow (BF) through the LVAD as the heart recovers. The main part of the control-drive unit is an automatic level control (ALC) system for left atrial pressure (LAP) and total flow (TF). Profound left ventricular failure (LVF) was made by complete interception of blood supply to the extent of 50% (5 goats) and 70% (5 goats) of the LV free wall. The air-driven diaphragm-type LVAD was implanted between LA and aorta. At the beginning of LVAD pumping, BF tended to be very high to keep LAP at the preset level (0-5 mmHg) and to maintain TF at somewhat higher level (120-140 ml/kg/min). The recovering heart was able to decrease LAP gradually. Since the LAP was set at a certain level, the ALC of LAP decreased BF to maintain LAP at the preset level. During the recovering stage from LVF, preset level of LAP was gradually raised while checking the pulmonary function. When natural heart output exceeded 100 ml/kg/min, LVAD was removed. The 50% LVF group recovered between 17 hours and 3 days, and 70% LVF group between 6th and 16th postoperative day. This LVAD system was then applied to the postoperative profound LVF in a MVR patient whose entire circulation was maintained normal during 14 day pumping. The failed heart gradually recovered and the pump was successfully removed. We consider that the decompression of LV will prevent overextension of impaired myocardium and simultaneously accelerate the solid scar formation. And gradual increase of LV work will promote the compensation ability of the residual myocardium. Continuous LVAD assistance can therefore earn time for the impaired myocardium to recover while maintaining normal circulation.

Adult↗
PubMed1981

Counterpulsation and dobutamine. Their use in treatment of cardiogenic shock due to right ventricular infarct.

A patient had right ventricular infarction complicated by cardiogenic shock. Volume expansion along with high doses of dopamine hydrochloride successfully alleviated hypotension in this patient. However, he had persistent mental obtundation and low cardiac output, and adverse chronotropic responses to high doses of dopamine developed. Counterpulsation effectively maintained an adequate arterial pressure and dopamine therapy was discontinued. Counterpulsation, however, failed to augment cardiac output. Simultaneous use of dobutamine hydrochloride along with counterpulsation was associated with a noticeable increase in cardiac output. To our knowledge, this is the first reported case of right ventricular infarct complicated by shock in which the simultaneous use of counterpulsation and dobutamine therapy resulted in a substantial increase in cardiac output.

Assisted Circulation↗