Low Output State Research Articles

Hypotension and cognitive impairment: Selective association in patients with heart failure.

Arterial hypotension has been associated with increased risk of dementia in some large prospective studies; and cognitive impairment is common among elderly with left ventricular function. The authors assessed whether arterial hypotension might be associated with cognitive impairment among older subjects with heart failure. This study involved all 13,635 patients (of whom 1,583 had heart failure) without cerebrovascular disease or AD, admitted to 81 Italian academic hospitals in 1995 and 1997. The association between blood pressure and cognitive impairment (as indicated by a Hodkinson Mental Test score < 7) according to the presence of heart failure was assessed by univariate analyses, including linear discriminant analysis. This association was also verified by multivariate analyses after stratifying for diagnosis of heart failure. Cognitive impairment was found in 26% of patients with heart failure and in 19% of remaining subjects (Fisher exact p < 0.0001). Blood pressure levels did not differ according to diagnosis of heart failure, but discriminant analysis indicated that systolic blood pressure levels below 130 mm Hg predicted cognitive impairment only among participants with heart failure. Among such participants, systolic blood pressure was associated with cognitive impairment in multiple logistic regression modeling (for 10 mm Hg intervals, OR = 0.78; 95% CI = 0.71 to 0.86). Again, this association was not found among participants without heart failure. Systolic hypotension is selectively associated with cognitive impairment in older patients with heart failure. As early treatment of cardiac low-output states can reverse cognitive dysfunction, the routine management of heart failure should include systematic assessment of cognitive performance.

Endothelin-1 blockade corrects mesenteric hypoperfusion in a porcine low cardiac output model.

To study the importance of endothelin-1-induced vasoconstriction in a model of acute and maintained low cardiac output, by investigating regional changes within the mesenteric and particularly the intestinal mucosal circulation. Prospective, controlled animal study. University-affiliated research laboratory. Thirteen fasted, anesthetized, mechanically ventilated landrace pigs. Cardiac output, portal venous blood flow, renal arterial flow, jejunal mucosal microcirculation by laser Doppler flowmetry, jejunal capnotonometry (Pco2 gap), and jejunal mucosal oxygenation (tPo2) were monitored. Cardiac tamponade was established to reduce portal venous blood flow to a preset end point at two thirds of baseline. Measurements were made at baseline, after 90 mins of cardiac tamponade, and 90 mins after the administration of the combined endothelinA/endothelinB antagonist tezosentan at 1 mg.kg-1.hr-1 during tamponade in seven animals. Six animals served as time controls and received only the vehicle. Cardiac tamponade decreased portal venous blood flow, renal arterial flow, and laser Doppler flowmetry, whereas the Pco2 gap increased. The change in tPo2 failed to gain statistical significance (p =.08). Administration of tezosentan during tamponade restored portal venous blood flow and laser Doppler flowmetry to baseline values, increased tPo2 above baseline, and decreased Pco2 gap. No effect on renal arterial flow was observed. Investigated variables remained unchanged in control animals after induction of cardiac tamponade. Endothelin-1 blockade in acute cardiac failure improves mesenteric, but not renal, perfusion, illustrating the regional importance of endothelin-1-induced vasoconstriction. Importantly, endothelin-1 blockade restored mucosal blood flow and oxygenation, which might be particularly interesting considering the implications for maintenance of mucosal barrier integrity in low output states.

Cardiac surgery in the octogenarian: evaluation of risk, cost, and outcome

Background. Nationwide, cardiac surgery is being performed more frequently in patients aged 80 years and older. Methods. One hundred four octogenarians undergoing a variety of heart–lung procedures were prospectively studied between 1995 and 1998 for comparison with similar patients aged 65 to 75 years (n = 351). Results. Octogenarians were more likely to be of female gender, and be nondiabetic than the younger group. The 30-day mortality rate for patients aged 65 to 75 years was 3.4% (12 of 351 patients), versus 13.5% (14 of 104) for patients aged 80+ ( p = 0.0004), which ranged from 2% (1 of 50) in nonemergent coronary artery bypass grafting to 75% (3 of 4) in double valve procedures. Complications occurring more frequently in octogenarians were severe low output state, reintubation, and atrial fibrillation. Elders experienced a longer intensive care (69.2 versus 43.3 hours, p = 0.002) and postoperative stay (10.09 versus 7.45 days, p = 0.001), and were discharged to a skilled nursing facility more often than younger patients (47% versus 21.1%, p = 0.0001). Total direct costs were $4,818 higher in the octogenarian group ( p = 0.0007). Conclusions. Although emergency operations and complex procedures carried high risks for the octogenarian, the majority of these patients can be offered operation with short-term morbidity, mortality, and resource use that only modestly exceeds that of younger patients.

Anticoagulation and heart failure.

There are no clear data regarding whether to use warfarin, aspirin, or no therapy in patients with left ventricular systolic dysfunction. Aspirin use is widespread in patients with vascular disease but it can decrease renal blood flow in low output states. Warfarin may be used in patients with advancing heart failure due to the perceived risk of in situ thromboembolism. However, we know that ejection fraction and symptom class do not always match and that the regulation of warfarin dosing is more difficult in worsening heart failure. Drug use must be individualized, based on knowledge of underlying heart failure etiology, functional class, drug side effects, and renal function. We await ongoing studies to elucidate the differential effects of these drugs on global outcome as well as on the mechanisms by which they achieve their results.

Arrhythmias: appraisal of symptoms by haemodynamic concepts

Arryhthmias can afflict any heart, even in the absence of disease. Given that Cardiac Output (CO) is a product of heart rate and stroke volume, the end-result of brady- and tachy-arrhythmias is the same: low CO with symptoms of low-output state. In bradyarrhythmias, myocardial inotropy operates maximally but the product of stroke volume and slow heart rate yields a low CO. In tacharryhthmias, myocardial inotropy is redundant because the product of low stroke volume arising from low Diastolic Filling Time (DFT) and heart rate also yields a low CO. The hallmark of extrasystole is the duplex of symptoms: dizziness followed by palpitation.

Part 6: Advanced Cardiovascular Life Support

Part 6: Advanced Cardiovascular Life Support

Endothelin-1: a new target of therapeutic intervention for the treatment of heart failure.

Endothelin-1 has been appreciated in animals and humans as a potential target for inhibition in patients with acutely decompensated congestive heart failure (CHF), as well as patients with a chronic low-output state. There has been intense interest in determining the effects of endothelin-1 on the cardiovascular system. Elevated plasma levels of endothelin-1 in patients with CHF portend a poorer prognosis than similar patients without elevated levels. Endothelin-1 levels correlate inversely with maximum oxygen consumption, and inhibition of the myocardial endothelin pathway in rats with CHF improves survival. An association between endothelin-1 and the development of CHF has recently been supported. Selectively inhibiting the endothelin A receptors in dogs with CHF produced hemodynamic improvement. Similarly, in rabbits, a structural advantage was demonstrated. Benefits in cardiac remodeling have been demonstrated in several models of CHF by nonselectively antagonizing endothelin receptors. In human trials using nonselective endothelin-1 inhibitors, researchers have demonstrated hemodynamic benefit and improvement in cardiac function in patients with decompensated CHF. Inhibition of endothelin-1 in patients with CHF appears to have potential therapeutic value, and ongoing clinical trials will further investigate the safety, efficacy, and role of this new potential therapeutic target for the treatment of CHF.

PII: S0003-4975(99)01297-7

Low output states leading to inadequate renal perfusion, atherosclerosis, diabetes, and nephrotoxins in the form of dyes and antibiotics all conspire to make patients undergoing cardiac surgery a high-risk population for renal failure. Most patients who develop acute renal failure (ARF) suffer from progressive low cardiac output. Some patients, such as those studied in this report by Sirivella and colleagues, probably experience a period of transient renal ischemia that will progress to ARF despite subsequent improvement in cardiac output and renal perfusion. In these patients, tubular epithelial disruption without frank tubular necrosis is often the pathologic response to transient ischemia that subsequently progresses to ARF. How are these patients best managed because renal function will usually recover with time? Avoidance of dialysis and maintenance of fluid and electrolyte balance while allowing renal function to recover has been the goal of a number of previous investigations. The combination of dopamine, mannitol, and furosemide, widely available and used commonly in cardiac surgery, was found by the authors to initiate a brisk diuresis and accelerate renal recovery. Although the mechanism was not elucidated by this study, the finding that earlier intervention is more effective suggests that one may recognize impending or early ARF and begin effective treatment. Although others have used this combination of drugs, this is the first clinical trial of postcardiotomy patients showing a reduced need for dialysis and an acceleration of recovery of renal function. It has significant implications in terms of use of resources and hospital costs. It will be an important additional step for the authors to determine if this therapy reduces morbidity and mortality in tandem with its reduction in the need for dialysis.

Ambulatory care of patients with left ventricular assist devices.

Left ventricular assist devices (LVAD) have revolutionized the treatment of patients with acute and chronic heart failure as they provide a high quality of life. We report on our experience with patients receiving ambulatory care after LVAD implantation. Since July 1995, 46 patients with a mean age of 45+/-11 years underwent implantation of an electrically driven LVAD with portable controller and batteries. Sixteen (35%) patients bridged >30 days were treated in part on an outpatient basis. After LVAD implantation, they were treated in the hospital for 86+/-32 days (range 40 to 153 days). Afterward, they received ambulatory care for 74+/-76 days (range 2 to 301 days, total experience 1206 days). In 13 cases, the outpatient treatment was interrupted by 1.7+/-1.7 readmissions, for a total of 32+/-42 days (median 19 days). Reasons for readmission included systemic or drive line infections (incidence 0.0066 per outpatient day), suspected or true thromboembolic events (incidence 0.0066 per outpatient day), and suspected malfunction of the LVAD. One patient supported as alternative to transplantation died after cerebral bleeding after 244 days, 1 patient with a history of acute myocarditis had ventricular fibrillation during LVAD assist while being at home for 177 days and died in a low output state, 10 patients were given transplantation after a mean support interval of 206+/-88 days, and 4 patients currently await heart transplantation. Outpatient treatment after LVAD implantation is feasible, and severe complications are uncommon.

Ambulatory Care of Patients With Left Ventricular Assist Devices

Background —Left ventricular assist devices (LVAD) have revolutionized the treatment of patients with acute and chronic heart failure as they provide a high quality of life. We report on our experience with patients receiving ambulatory care after LVAD implantation. Methods and Results —Since July 1995, 46 patients with a mean age of 45±11 years underwent implantation of an electrically driven LVAD with portable controller and batteries. Sixteen (35%) patients bridged &gt;30 days were treated in part on an outpatient basis. After LVAD implantation, they were treated in the hospital for 86±32 days (range 40 to 153 days). Afterward, they received ambulatory care for 74±76 days (range 2 to 301 days, total experience 1206 days). In 13 cases, the outpatient treatment was interrupted by 1.7±1.7 readmissions, for a total of 32±42 days (median 19 days). Reasons for readmission included systemic or drive line infections (incidence 0.0066 per outpatient day), suspected or true thromboembolic events (incidence 0.0066 per outpatient day), and suspected malfunction of the LVAD. One patient supported as alternative to transplantation died after cerebral bleeding after 244 days, 1 patient with a history of acute myocarditis had ventricular fibrillation during LVAD assist while being at home for 177 days and died in a low output state, 10 patients were given transplantation after a mean support interval of 206±88 days, and 4 patients currently await heart transplantation. Conclusions —Outpatient treatment after LVAD implantation is feasible, and severe complications are uncommon.

Cardiopulmonary Interactions After Fontan Operations

Background The low-output state is the chief cause of morbidity and mortality after Fontan operations. An alternative hemodynamic tool would be a welcome addition for these patients, who are typically resistant to conventional therapeutic measures. Methods and Results The hemodynamic effects of conversion from conventional intermittent positive pressure ventilation (IPPV) to cuirass negative pressure ventilation (NPV) was investigated in nine acute postoperative Fontan patients on the pediatric intensive care unit and nine anesthetized patients undergoing cardiac catheterization in the convalescent phase after Fontan operations. Pulmonary blood flow was measured using the direct Fick method during IPPV and after a brief period of NPV. In one subgroup of patients, pulmonary blood flow was measured again after reinstitution of IPPV, and in a second subgroup, pulmonary blood flow was measured after an extended period of NPV. A brief period of NPV increased pulmonary blood flow from 2.4 to 3.5 L · min−1 · /m−...

Cerebral injury after cardiac surgery: identification of a group at extraordinary risk. Multicenter Study of Perioperative Ischemia Research Group (McSPI) and the Ischemia Research Education Foundation (IREF) Investigators.

Cerebral injury after cardiac surgery is now recognized as a serious and costly healthcare problem mandating immediate attention. To effect solution, those subgroups of patients at greatest risk must be identified, thereby allowing efficient implementation of new clinical strategies. No such subgroup has been identified; however, patients undergoing intracardiac surgery are thought to be at high risk, but comprehensive data regarding specific risk, impact on cost, and discharge disposition are not available. We prospectively studied 273 patients enrolled from 24 diverse US medical centers, who were undergoing intracardiac and coronary artery surgery. Patient data were collected using standardized methods and included clinical, historical, specialized testing, neurological outcome and autopsy data, and measures of resource utilization. Adverse outcomes were defined a priori and determined after database closure by a blinded independent panel. Stepwise logistic regression models were developed to estimate the relative risks associated with clinical history and intraoperative and postoperative events. Adverse cerebral outcomes occurred in 16% of patients (43/273), being nearly equally divided between type I outcomes (8.4%; 5 cerebral deaths, 16 nonfatal strokes, and 2 new TIAs) and type II outcomes (7.3%; 17 new intellectual deterioration persisting at hospital discharge and 3 newly diagnosed seizures). Associated resource utilization was significantly increased--prolonging median intensive care unit stay from 3 days (no adverse cerebral outcome) to 8 days (type I; P<0.001) and from 3 to 6 days (type II; P<0.001), and increasing hospitalization by 50% (type II, P=0.04) to 100% (type I, P<0.001). Furthermore, specialized care after hospital discharge was frequently necessary in those with type I outcomes, in that only 31% returned home compared with 85% of patients without cerebral complications (P<0.001). Significant risk factors for type I outcomes related primarily to embolic phenomena, including proximal aortic atherosclerosis, intracardiac thrombus, and intermittent clamping of the aorta during surgery. For type II outcomes, risk factors again included proximal aortic atherosclerosis, as well as a preoperative history of endocarditis, alcohol abuse, perioperative dysrhythmia or poorly controlled hypertension, and the development of a low-output state after cardiopulmonary bypass. These prospective multicenter findings demonstrate that patients undergoing intracardiac surgery combined with coronary revascularization are at formidable risk, in that 1 in 6 will develop cerebral complications that are frequently costly and devastating. Thus, new strategies for perioperative management--including technical and pharmacological interventions--are now mandated for this subgroup of cardiac surgery patients.

Cardiorespiratory responses to negative pressure ventilation after tetralogy of Fallot repair: a hemodynamic tool for patients with a low-output state

ObjectivesWe hypothesized that a period of cuirass negative pressure ventilation (NPV) would augment the cardiac output of patients in the early postoperative period after complete correction of tetralogy of Fallot (TOF).BackgroundDiastolic right ventricular dysfunction can lead to a low-output state in an important minority of patients after TOF repair. In these patients, the diastolic pulmonary arterial flow, which characterizes restrictive right ventricular physiology, and on which the cardiac output is so dependent, is highly sensitive to changes in intrathoracic pressure.MethodsThe effects of NPV on pulmonary blood flow were investigated in 23 intubated children who were initially ventilated using intermittent positive pressure ventilation after TOF repair. Eight patients had restrictive right ventricular physiology. All children received a 15-min period of NPV, and eight received a prolonged period (45 min) of NPV.ResultsA brief period of NPV increased pulmonary blood flow by 39%, and the improvement further continued if the study period was extended, with a total increase of 67% after 45 min. Patients with restrictive physiology had a somewhat delayed response to NPV, but the ultimate increase during an extended period of NPV was greater in restrictive patients (84%) than nonrestrictive patients (50%).ConclusionsBy manipulating important cardiopulmonary interactions, NPV improves the cardiac output of patients after TOF repair, and has a role as a hemodynamic tool in the management of the low-output state in selected cases.

Aortic Atherosclerosis Predicts Postoperative Renal Dysfunction

Cardiac surgical procedures carry a relatively high risk of acute renal failure. Previously reported associated factors include advanced age, impaired left ventricular (LV) function, active bacterial endocarditis, pre-existing renal dysfunction, prolonged aortic cross-clamp time, and a postoperative low output state. This prospective U.S. study evaluated the importance of …

The Northern New England Cardiovascular Disease Study Group: A Regional Collaborative Effort for Continuous Quality Improvement in Cardiovascular Disease

The Northern New England Cardiovascular Disease Study Group, a voluntary regional consortium, includes all cardiothoracic surgeons and interventional cardiologists, as well as nurses, anesthesiologists, perfusionists, administrators, and scientists associated with the six medical centers in Maine, New Hampshire, and Vermont and one Massachusetts-based medical center that support coronary artery bypass graft (CABG) surgery and percutaneous coronary interventions (PCI). Since 1987 the group has met at least three times a year to foster improvements in patient care. The group's activities have included continued monitoring of outcomes, training in continuous quality improvement, and a benchmarking effort that allowed institutions to learn from one another. In the postintervention period (mid-1991 through early 1992) there were 293 fewer deaths (n = 575) than the 868 expected. In 1995 a new cycle of quality improvement work aimed at identifying the causes and correlates of postoperative mortality began. Study groups for each institution were organized to examine issues related to death from low-output states. Major improvement in hospital outcomes have occurred in relation to the improving technology (primarily coronary stenting). Near-twofold variability in the use of stents has led to vigorous discussions about the role of new devices. Randomized clinical trials are very important to assessing the effects of specific treatments, but most of what is known about actual clinical care will come from observational studies. Demonstrating the variability in practice patterns can be a potent stimulus to try to answer the important questions.

Induced hypothermia in the postoperative management of refractory cardiac failure following paediatric cardiac surgery.

Postoperative low cardiac output states are a major cause of postoperative mortality in infants and children following corrective cardiac surgery for congenital heart defects. In this unit, whole body hypothermia has been used since 1979 in the management of these low output states when they are refractory to conventional modes of therapy. Twenty cases treated in this way between July 1986 and June 1990 were reviewed in 1992. The current report reviews the 50 further cases treated with moderate hypothermia between July 1990 and December 1995. The median (range) age of patients was 8 months (0 days-16 years) with a median weight of 4.1 kg (2.5-33 kg). Following cooling, there was a decrease in heart rate (p < 0.001), an increase in mean arterial pressure (p < 0.001) and a decrease in mean atrial pressure (p < 0.001). Significant increases in pH and urine output were also noticed, the increase in urine output being greater in the surviving group (p = 0.02). A decrease in platelet count occurred (p < 0.001) but white blood cell count remained unchanged (p = 0.18). Twenty-five of the 50 patients survived to leave hospital. Induced hypothermia does not appear to be associated with any complications and after the failure of all conventional treatment, it seems likely that the technique may have been beneficial to outcome in some patients.

Development and Pathophysiological Basis of Thrombolytic Therapy in Acute Myocardial Infarction Part I. 1912–1977 The Controversy Over the Pathogenetic Role of Thrombus in Acute Myocardial Infarction

Although acute myocardial infarction (MI) was among the indications of Fletcher's 1959 safety study of thrombolytic therapy, this indication was not pursued in subsequent U.S. trials. The 1977 FDA approval of thrombolytic therapy did not include acute MI. The view that coronary thrombus, due to rupture of the underlying plaque and frequently associated with dissecting hemorrhage from the lumen into the plaque causes MI, had lost its dominance. Branwood had concluded that coronary thrombosis was not the cause but the consequence of MI, occurring in a minority of patients. Paterson had ascribed plaque hemorrhage to rupture of capillaries within the plaque. Autopsy studies in the mid‐1960s provided fresh evidence that coronary thrombi were common in acute MI and that intimal fissuring caused both intraluminal thrombosis and plaque hemorrhage. Despite this, Robert's view that plaque fissures were artifacts resulting from sectioning arteries, and that coronary thrombosis resulted from a prolonged low output state associated with large infarcts, prevailed. Meanwhile, European investigators continued to explore thrombolysis in acute MI, although they believed that the lysis time for a coronary thrombus exceeded the time limit of myocardial tolerance of anoxia. They hoped to improve collateral flow and microcirculation by lysing microthrombi in capillaries and venules within and around the infarct zone. The reduction in blood viscosity associated with fibrinolytic therapy was expected to further improve collateral flow and to decrease myocardial oxygen demand by reducing afterload. The discussion about the pathogenesis of acute MI was limited by the inherent selection bias of autopsy studies and a paucity of in vivo angiographic data.

Development of a Correction Factor for Quantifying Stenotic Valve Area at Low Output States Using the Doppler Continuity Equation: In Vitro Validation

Development of a Correction Factor for Quantifying Stenotic Valve Area at Low Output States Using the Doppler Continuity Equation: In Vitro Validation

Development of a correction factor for quantifying stenotic valve area at low output states using the Doppler continuity equation: in vitro validation

Development of a correction factor for quantifying stenotic valve area at low output states using the Doppler continuity equation: in vitro validation

Cardiopulmonary interactions after Fontan operations: augmentation of cardiac output using negative pressure ventilation.

The low-output state is the chief cause of morbidity and mortality after Fontan operations. An alternative hemodynamic tool would be a welcome addition for these patients, who are typically resistant to conventional therapeutic measures. The hemodynamic effects of conversion from conventional intermittent positive pressure ventilation (IPPV) to cuirass negative pressure ventilation (NPV) was investigated in nine acute postoperative Fontan patients on the pediatric intensive care unit and nine anesthetized patients undergoing cardiac catheterization in the convalescent phase after Fontan operations. Pulmonary blood flow was measured using the direct Fick method during IPPV and after a brief period of NPV. In one subgroup of patients, pulmonary blood flow was measured again after reinstitution of IPPV, and in a second subgroup, pulmonary blood flow was measured after an extended period of NPV. A brief period of NPV increased pulmonary blood flow from 2.4 to 3.5 L x min(-1) x /m(-2), with a mean increase of 42%. Pulmonary blood flow continued to improve, with a total increase of 54% after an extended period of NPV. Values fell toward baseline after reinstitution of IPPV. Heart rate was unchanged during NPV, and the improvement in pulmonary blood flow was achieved by an increase in stroke volume from 25 mL/m2 to 37 mL/m2. Through improvement of the stroke volume alone, NPV brought about a marked increase in the pulmonary blood flow and, hence, cardiac output of Fontan patients. An improvement in cardiac output of this order, and by this mechanism, is currently unmatched by any therapeutic alternatives.