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PubMed1992

Effect of synchronous and asynchronous pulsatile flow during left, right, and biventricular bypass.

Ventricular assist devices augment flow from the left atrium to the aorta and/or from the right atrium to the pulmonary artery. Most devices are used in the asynchronous full-to-empty mode (asynchronous) but may also be used in a synchronous counterpulsation mode (synchronous). This study determines the optimal assist modes to reduce myocardial oxygen consumption (MVO2) and metabolism. Twelve pigs were instrumented with carotid artery and Baim coronary sinus catheters for determination of MVO2 and myocardial lactate production (LACT). Six were implanted with a Pierce-Donachy left ventricular assist device (LVAD) and 6 with both right and left ventricular assist devices (BIVAD). Two periods each of control, synchronous, and asynchronous bypass were instituted, the midanterior descending coronary artery (LAD) was ligated, and the sequence was repeated. After each period, MVO2 and LACT were determined and myocardial biopsy specimens were obtained for tissue, lactate, and ATP assay. Following LAD ligation, biopsy specimens were obtained from both the infarct and noninfarct zones of the heart. MVO2 decreased (p < 0.05) in the asynchronous BIVAD mode compared with control. MVO2 was unchanged in synchronous BIVAD or either LVAD mode. Tissue ATP and tissue lactate were unaffected by any mode of bypass. Only BIVAD in the asynchronous mode reduced MVO2. When ventricular assist devices are utilized to aid recovery of the natural heart, two devices should always be inserted to allow biventricular assist. Synchronous counterpulsation offers no advantage.

Adenosine Triphosphate↗
PubMed1996

Skeletal muscle ventricles: frontiers in 1995.

Skeletal muscle ventricles (SMVs) constructed from electrically conditioned latissimus dorsi muscle (LDM) may become an alternative for assisting the failing heart. Left and right heart circulatory assist using SMVs has been performed successfully in both acute and chronic animal models. The configurations used to connect SMVs to the circulation have included a left atrium to aorta bypass, a left ventricle apex to aorta bypass, aortic counterpulsators, a cavopulmonary bypass, and a right ventricle to pulmonary artery bypass. One SMV used as an aortic counterpulsator functioned effectively in the circulation for more than 27 months. Recent application of the pericardium to the SMV as an inner layer and design changes in the connection of the SMV to the circulation have reduced the risk of thrombus formation and SMV rupture. Although several problems have yet to be solved, the goal of the SMV as a permanent circulatory assist device without the limitation of an external power source seems within reach.

Animals↗
PubMedDate not supplied

Skeletal muscle ventricles in continuity with the bloodstream.

BACKGROUND AND AIM OF STUDY: The prevalence of end-stage congestive heart failure and limitation of clinical alternative treatments present the need for creative new solutions. Formation of a ventricle from skeletal muscle (SMV) has shown promise in the animal laboratory. Two modes of the SMV for cardiac assistance, the counterpulsation (CP-SMV) and the ventricular assist (VA-SMV), using the latissimus dorsi muscle were applied in a canine model. Ability to augment arterial pressure was assessed. The effect of stimulation delay on the degree of augmentation was also evaluated. METHODS AND RESULTS: Thirty-five SMVs were connected in continuity with the bloodstream in the two modes: (1) CP-SMV (aorta-to-aorta) (n = 12); and (2) VA-SMV (left ventricular [LV] apex-to-aorta) (n = 23). In the CP-SMV mode, designed to simulate the intra-aortic balloon pump, the SMV was simply interposed into the path of the descending aorta (DAo) without prosthetic valves in either the inflow or the outflow conduit. In order to obligate blood flow through the SMV, the DAo was ligated between the two grafts. In the VA-SMV mode, the connection was made with valved conduits from the LV apex (inflow) to the ascending aorta (outflow) (n = 11) or to the DAo (n = 12). The ascending aorta (AAo) was also ligated proximal to the outflow conduit for the same reason of obligating blood flow through the SMV. The SMV was timed to contract in diastole in both the CP-SMV mode and the VA-SMV mode. In the VA-SMV mode, the average systolic pressure without stimulation was 101.6 +/- 2.2 mmHg and with stimulation 118.21 +/- 4.78 mmHg (mean augmentation, 14.5 +/- 2.6 mmHg) (p < 0.01). In the CP-SMV mode, the average systolic pressure without stimulation was 97 +/- 32 mmHg and with stimulation, 122 +/- 26 mmHg (mean augmentation, 25 +/- 8.6 mmHg) (p < 0.001). We also extended earlier work on timing of stimulation of isolated SMV by evaluating the effect of stimulation delay on the degree of augmentation in continuity with the bloodstream with the SMV in the VA-SMV configuration. Delays of 50 msec to 225 msec were evaluated. SMV stimulation was via the thoracodorsal nerve at an amplitude of 1.5 V and a frequency of 25 Hz. The greatest augmentation occurred at a stimulation delay of 150 msec (p < 0.001). CONCLUSION: Both counterpulsation and assist configurations produced effective diastolic augmentation. Although diastolic augmentation occurred with all timing delays, the optimal delay was 150 msec. Complications in the survival animals include AAo problems, SMV rupture, respiratory insufficiency, intraoperative instability, and thrombosis (which occurred in 51% [18/35] of the animals). This high frequency of thrombosis in the canine model suggests the use of a less thrombogenic SMV lining, more aggressive or prolonged anticoagulation, or an alternative animal model.

Animals↗
PubMed1975

Acute severe cardiac failure complicating myocardial infarction. Experience with 100 patients referred for consideration of mechanical left ventricular assistance.

One hundred patients were referred with suspected acute cardiac failure following acute myocardial infarction. The diagnosis was confirmed in 72: 31 of these patients underwent elective medical treatment, with 2 survivors (6%); 41 were accepted for counter pulsation, but 9 died before this could be initiated and another 2 died shortly after vain attempts to pass the balloon catheter were abandoned; 30 patients underwent counterpulsation with 14 hospital survivors (47%). Survivor status was usually good. Results of counter pulsation were better in patients who were not shocked (with 5/5 survivors) than in those who were in shock (with 9 of 25 survivors). Results support the view that counterpulsation (alone or combined with corrective surgery) may play an important role in the complications of myocardial infarction provided intervention is early.

Acute Disease↗
PubMed2006

Effects of intraaortic balloon pumping on the angiographic no-reflow phenomenon after percutaneous coronary intervention in patients with anterior myocardial infarction.

BACKGROUND: The effects of intraaortic balloon pumping (IABP) are considered to be a reduction in myocardial oxygen demand because of systolic left ventricular unloading and an increase in coronary blood flow. Although the former effect has been consistently recognized, the latter effect remains controversial. The purpose of this study was to examine the effects of IABP on the angiographic no-reflow phenomenon. METHODS AND RESULTS: The coronary flow velocity pattern of the left anterior descending artery (LAD) was assessed by transthoracic Doppler echocardiography during IABP counterpulsation, and the effects of IABP were compared between angiographic no-reflow and good reflow patients. The study group comprised 17 patients with anterior myocardial infarction who underwent percutaneous coronary intervention and IABP for typical clinical indications. Echocardiographic data were obtained during 2:1 balloon pumping after coronary angioplasty. In the good reflow group (n=9), IABP counterpulsation increased the mean diastolic flow velocity (MDFV) and peak diastolic flow velocity (PDFV) by 56 +/- 32% (p<0.001) and 48 +/- 27% (p<0.001), respectively. In contrast, in the no-reflow group (n=8), IABP only increased the MDFV and PDFV by 19 +/- 33% (p=0.24) and 6 +/- 12% (p=0.22), respectively. Diastolic deceleration time was smaller and the prevalence of systolic retrograde flow was greater in the no-reflow group than in the good reflow group, and IABP affected neither parameter. CONCLUSIONS: IABP had limited effects on LAD flow velocity pattern in patients with the angiographic no-reflow phenomenon.

Aged↗
PubMedDate not supplied

[Surgical complications and mortality in octogenarian patients undergoing revascularization surgery].

UNLABELLED: Our objective was to identify preoperative, operative and postoperative factors associated with complications and mortality in patients equal to or greater than 70 years of age with coronary artery disease treated with coronary bypass surgery. From january 1990 to june 1994 of those that underwent 37 coronary artery bypass surgery. 32 were men (86.5%) and five women (13.5%). History of cardiovascular disease, diabetes mellitus, systemic arterial hypertension, pulmonary disease, hypercholesterolemia, renal function, and severity of coronary artery disease were considered. Also analysed were aortic clamp and cardiopulmonary bypass time, number and type of grafts. Use of intraaortic balloon counterpulsation, inotropic drugs, ventilatory support, hemorrhage, infection, renal and liver failure, neurological, rhythm and conduction abnormalities and myocardial ischemia were also considered. Identified risk factors: diabetes mellitus, (p = 0.028), ejection fraction < 30% (p = 0.023), ventricular wall motion abnormalities (p < 0.05), aortic clamp > 60 minutes (p = 0.026), cardiopulmonary bypass < 120 minutes (p = 0.022), reverse saphenous vein grafts (p = 0.014), prolonged ventilatory support, inotropic drugs and intraaortic balloon counterpulsation. CONCLUSIONS: Surgery should be reserved for patients with at least three vessel or left main coronary artery disease or proximal lesion of the left anterior descending artery with severe ischemia, deteriorated myocardial function and angina with no response to medical treatment; age of the patient is not a contraindication.

Aged↗
PubMed1999

Paraplegia following intraaortic balloon circulatory assistance.

Intraaortic balloon counterpulsation is frequently used in patients experiencing severe ventricular dysfunction following maximal drug therapy. However, even with the improvement of percutaneous insertion techniques, the procedure has always been followed by vascular; infectious, and neurological complications. This article describes a case of paraplegia due to intraaortic balloon counterpulsation in the postoperative period of cardiac surgery.

Humans↗
PubMed1975

Electrolyte changes in myocardial injury.

The shifts in the myocardial electrolyte metabolism during secondary or primary cardiopathies in dogs and rats, respectively, are described. Major attention is paid to the changes of Ca in the myocardial tissue. The increase in the Ca level after ligation of ramus circumflex of the left coronary artery, or after F-COL + Na2HPO4, and vitamin D2 administration, is regarded as a triggering process for more profound successive changes in the metabolism of the myocardial cell, which eventually lead to depletion of the high energy phosphate reserves. In the dogs with experimental coronary occlusion, the normalization of the myocardial ionogram, i.e., the ratio of K, Na, Ca, and Mg, was achieved by means of the mechanical heart assist, using the original design of the blood pump, where bypass and counterpulsation principles work simultaneously. The normalization of the Ca level in this case was achieved on the basis of a marked reduction of the volume work of the left ventricle, which is secured by the bypass component; on the other hand, the counterpulsation component of the combined pump secures the reduction of pressure work placed upon the left ventricle (represented by the decrease fo the end-diastolic pressure) and helps in the opening of the collaterals in the infarcted area during early diastole. Thus, the oxygen supply to the ischemic zone is improved. On the basis of our experiments with the combined blood pump, the failing heart is supported, not only hemodynamically, but also from the metabolic point of view. A similar effect is achieved by the administration of K-Mg-aspartate, and K-L- or K-DL-aspartate in dogs with experimental infarction. In primary electrolyte steroid cardiopathies characterized by necrosis, K-Mg-aspartate or K-aspartate only prevents the Ca increase in the myocardial tissue, whereas Mg-L- or Mg-DL-aspartate remains without andy effect. The necrotic changes observed after vitamin D2 administration are always accompanied by extremely high Ca levels in the myocardium. It shown in our experiments that administration of K-Mg-aspartate or Fe-dextran decreases the Ca level and reduces the necrotic and myolytic changes in the cardiac tissue. The authors recommend as an effective means in the therapy of acute heart failure the combination of mechanical heart support with the causative pharmacological therapy.

Animals↗
PubMed2004

[Clinical features and treatment of cardiogenic shock complicated with acute myocardial infarction].

OBJECTIVE: To identify the clinical features and the outcome of patients with cardiogenic shock complicating acute myocardial infarction (AMI). METHODS: One hundred and eight consecutive patients with AMI were included in this retrospective analysis. The characteristics, management, and outcome of patients with AMI were compared between patients with cardiogenic shock (group A, n=11) and without cardiogenic shock (group B, n=9). RESULTS: There was no difference in the age and other characteristics including proportion of women, diabetics, prior myocardial infarction and the position of myocardial infarction. The levels of peak creatine kinase and troponin I were (31979.7+/-22271.1)nmol x s(-1) x L(-1) and (90.7+/-61.1) microg/L respectively in group A, they were higher than those in group B (17795.2+/-14979.7)nmol.s-1.L-1 and (39.9+/-52.1) microg/L, respectively (both P<0.05). The left ventricular ejection fraction was significantly lower in group A than that in group B (0.46+/-0.12 vs. 0.55+/-0.12, P<0.05). Patients in group A had a higher proportion of pump failure, arrhythmia and pneumonia (64% vs. 14%, P<0.001; 55% vs. 21 %, P<0.05; and 46% vs. 12%, P<0.01, respectively) than those in group B. In addition, in group A patients often underwent thrombolysis of urokinase, coronary angiography and intra-aortic balloon counterpulsation (46% vs. 18%, 73% vs. 26% and 36% vs. 4%, all P<0.05, respectively). There was no difference in in-hospital mortality between group A and group B (0 vs. 4%, P>0.05). CONCLUSION: Shock patients more likely have pump failure, arrhythmia, and pneumonia and more often underwent intra-aortic balloon counterpulsation. If cardiogenic shock complicating AMI is managed with rapid evaluation and prompt initiation of supportive measures and definitive therapy, outcomes can be improved.

Adult↗
PubMed2004

[Primary percutaneous coronary interventions in acute myocardial infraction with ST-segment elevation. Experience in a heart catheterization unit without surgical backup].

BACKGROUND: Primary percutaneous coronary intervention (PCI) in patients (pts) with ST-segment elevation myocardial infarction is regarded as treatment superior to thrombolysis. Coronary stents and GP IIb/IIIa receptor inhibitors improved safety and clinical outcome of interventional procedures. Safety of primary PCI procedure in catheterisation laboratories which do not have on-site surgical backup is still under evaluation. METHODS: In a cohort of 249 consecutive patients we analysed short and long-term clinical outcome of primary PCI performed in catheterisation laboratory which is located several kilometres from a cardiac surgery department, with an effective transfer time < 30 minutes. RESULTS: Coronary stents were implanted in 43% pts. GP IIb/IIIa receptor inhibitors were used in 54.2% pts. Cardiogenic shock on admission was diagnosed in 7.2% pts. Intra-aortic balloon counterpulsation usage was necessary in 6.4% pts. In-hospital mortality was 6% (3.5% in non-shock pts). In two pts (0.8%) during hospitalization repeat PCI was performed--in one case due to reinfarction. No urgent cardiosurgery intervention was necessary. Mortality and myocardial infarction rate after hospital discharge during 6 month follow up was 2.4% and 2.8% respectively. In 4% pts repeated PCI was performed due to restensosis. Cumulative event free survival was 84%. CONCLUSION: Primary PCI procedure for acute myocardial infarction seems to be feasible and safe in catheterisation laboratories without on-site surgical backup provided usage of stents, GPIIb/IIIa receptor inhibitors and intraaortic balloon counterpulsation and cooperation with a nearby cardiosurgery department with short transfer time.

Aged↗
PubMed2006

Simultaneous papillary muscle avulsion and free wall rupture during acute myocardial infarction. Intra-aortic balloon pump: a bridge to survival.

Mechanical complications of acute myocardial infarction (AMI) are rare, but often fatal. Medical therapy does not provide adequate risk reduction, and surgical correction is recommended when feasible. Supplemental hemodynamic support utilizing intra-aortic counterpulsation with a balloon pump provides an improvement in morbidity and mortality when combined with a corrective surgical approach. We report a case of an elderly male with a progressive 2-week history of ischemic symptoms presenting with acute pulmonary edema, hypotension and an inferior wall ST-elevation MI. His hospital course was complicated by ischemic mitral regurgitation (MR) and cardiogenic shock, which resulted in a papillary muscle rupture/avulsion from the inferolateral myocardial wall, and a communication for blood from ventricle to pericardial space. Initial management included mechanical ventilation, pharmacologic inotropic support, percutaneous revascularization of the culprit lesion and intra-aortic balloon counterpulsation. The patient underwent further successful cardiovascular surgical correction of his incompetent mitral valve, free wall rupture and other obstructive coronary arteries, leading to discharge and survival. Mechanical complications from AMI and the role of intra-aortic balloon support are discussed.

Aged, 80 and over↗
PubMed1990

Experimental study of renal sympathetic nerve activity during left ventricular assist device pumping.

To determine the effect of left ventricular assist device (LVAD) pumping on sympathetic tone, renal sympathetic nerve activity (RSNA) was recorded in acute animal experiments. Our TH-7B pneumatically driven sac type ventricular assist device (VAD) was used in 7 adult mongrel dogs. RSNA was detected by use of bipolar electrodes attached to the left renal sympathetic nerve under conditions of various LVAD pumping modes. All hemodynamic data and the RSNA were calculated with a personal computer system. In general, LVAD assistance produced increased systolic aortic pressure, increased pulmonary artery flow and decreased left atrial pressure, which caused decreased RSNA, especially in the counterpulsation mode. These results suggest that renal vascular resistance might be reduced in parallel with the decrease of RSNA. Thus, counterpulsation mode LVAD assistance has the more evident effect in preventing acute prerenal renal failure.

Animals↗
PubMedDate not supplied

A novel mechanical cardiac assist device for reversing left ventricular failure.

Diastolic augmentation of aortic pressure is an efficacious means of improving coronary perfusion in heart failure. A novel mechanical cardiac assist device (MCAD), that has advantages over a conventional intraaortic balloon pump and left ventricular assist devices, has been developed. It consists of a high efficiency rotary solenoid, coupled to a pair of actuator plates that clamp on a shunt aortic graft section, and operates in a diastolic counterpulsation mode. The system has been evaluated in six anesthetized, thoracotomized dogs with myocardial ischemia. The MCAD was activated 30-40 min after coronary artery occlusion and synchronized with the R-wave. As illustrated by a representative sample of the data obtained from one of several trials, the preliminary experimental results demonstrated that the MCAD worked effectively to fulfill the primary functions of a counterpulsation assist device, i.e., augmentation of coronary perfusion and reduction in the vascular impedance to ventricular ejection.

Animals↗
PubMed1990

[The most frequently used methods of assisted circulation].

An account of the most widely used mechanical synchronized types of assisted circulation for the control and management of circulatory failure. Intraaortal ballon counterpulsation is in specialized departments already a routine method. When comparing intraaortal ballon counterpulsation with the bypass method of volume relief of the ventricle, based on the bioenergetic index, the latter method of assisted circulation is more effective. The authors draw attention to the bypass method of assisted circulation involving transdiaphragmatic cannulation of the left ventricle--aorta by laparotomy, without thoracotomy.

Assisted Circulation↗
PubMed1979

Aortocoronary bypass for critical stenosis of the left main coronary artery.

Over a 2-year period 33 patients with symptomatic stenosis (greater than 75%) of the left main coronary artery underwent aortocoronary bypass. Intra-aortic balloon counterpulsation was used preoperatively in only two patients as a therapeutic measure for medically unstable angina. There were no operative deaths. Follow-up study 3 to 27 months (mean 13.3 months) after operation revealed one death. Twenty-two patients were free of pain. The authors conclude that aortocoronary bypass surgery for severe stenosis of the left main coronary artery can be safely accomplished, without prophylactic use of intra-aortic balloon counterpulsation in the majority of cases, with an acceptable operative mortality and morbidity.

Adult↗
PubMed1987

Skeletal muscle ventricles in circulation. One to eleven weeks' experience.

Skeletal muscle ventricles were constructed from canine latissimus dorsi and connected to the thoracic aorta in six dogs. These ventricles were stimulated to contract synchronously during diastole. The skeletal muscle ventricles were capable of continuous stroke work when placed within the arterial circulation for several weeks. Effective synchronous diastolic counterpulsation was produced. These results demonstrate that diastolic counterpulsators can be constructed from skeletal muscle and in the future may provide a feasible therapeutic alternative for the treatment of end-stage cardiac failure.

Animals↗
PubMed1987

Perioperative right heart failure: treatment.

When right ventricular failure prohibits separation from cardiopulmonary bypass, standard methods of increasing pulmonary blood flow should be employed, including correction of hypoxia and acidosis, volume loading, and inotropic support of the right ventricle. Infusion of pulmonary vasodilators--particularly low-dose nitroprusside--should be used if the pulmonary vascular resistance is elevated. If pulmonary blood flow remains unsatisfactory, systemic intra-aortic balloon counterpulsation should be employed. In refractory cases, right-atrial-to-pulmonary-artery bypass using the Bio-Medicus centrifugal pump is the recommended therapy for those centers that do not have the Pierce-Donachy pneumatic ventricular assist-pump available. For refractory right ventricular failure following the surgical repair of congenital cardiac defects in which the placement of right atrial and pulmonary artery cannulae is not technically feasible, use of high-frequency high-volume ventilation appears to be quite promising. Utilization of pulmonary artery counterpulsation or the creation of an atrial septal defect may also be lifesaving, but is not recommended as the therapy of choice.

Cardiopulmonary Bypass↗
PubMed1979

[Clinical application of a supplement to the extracorporal circulation to produce a pulsatile flow (author's transl)].

Two groups of patients with atherosclerotic coronary artery disease, who underwent aortocoronary bypass operation, were perfused with nonpulsatile flow during extracorporeal circulation (ECC) using membrane oxygenators. One group (MO) was used as a control, while for the other group (PAD) a Pulsatile Assist Device in the arterial line was employed. This apparatus consists of a balloon of 80 ml placed inside a rigid housing. The balloon is compressed by pressurized air or expanded by vacuum supplied by a driving console. The apparatus produced pulse amplitudes between 30 and 50 mm of mercury. Other than a very short-lasting fall in mean arterial pressure, thus showing diminished peripheral resistance, no perceptable advantages were found. Base excess and pH-changes showed no differences, also the given amount of sodium bicarbonate in both groups was the same. On the other hand significantly higher hemolyses took place, increasing with the duration of pulsation. The application of the apparatus as an arterial counterpulsator was possible with limitation in only 5 of 15 patients. In all other patients after a short time massive blood foaming developed in the PAD and the attempts had to be stopped because of the risk of gas embolism. In our opinion this apparatus is an unnecessary supplement to the ECC and as an arterial counterpulsator it seems too dangerous.

Adult↗