Acute descending aortomyoplasty induces coronary blood flow augmentation

BACKGROUND: Aortomyoplasty is a procedure aimed to improve cardiac output in patients suffering from heart failure. Stimulation of the latissimus dorsi muscle around the aorta produces hemodynamic effects similar to those of the intraaortic balloon pump. These may be maintained without the accompanying complications or the need for anticoagulation. The objective of this study was to test the acute effects of aortomyoplasty on coronary artery blood flow. METHODS: Eight mongrel dogs (18 to 30 kg) underwent acute descending aortomyoplasty. Several stimulation protocols were applied after wrapping of the latissimus dorsi muscle around the aorta in different surgical configurations. The left anterior descending coronary blood flow was measured using a transonic Doppler flow probe. Left ventricular and aortic pressures, proximal and distal to the aortomyoplasty site, were monitored continuously. RESULTS: Significant aortic diastolic pressure augmentation was expressed both as an increase in peak values, from 110 +/- 24 mm Hg to 120 +/- 24 mm Hg (p < 0.001) and as an increase in the diastolic integral, from 64 +/- 23 mm Hg x s to 84 +/- 37 mm Hg x s (p < 0.001). Concomitantly, peak left anterior descending coronary blood flow increased from 26 +/- 10 mL/min to 32 +/- 12 mL/min (p < 0.001). This was associated with an increase in the diastolic flow integral from 11 +/- 4 mL to 14 +/- 6 mL (p < 0.001). CONCLUSIONS: Descending aortomyoplasty induces significant augmentation of coronary blood flow. Optimal timing of muscle stimulation is important in achieving the best assist. This procedure may prove beneficial for end-stage ischemic patients.     

Dynamic aortomyoplasty in treating end-stage heart failure.

BACKGROUND: Dynamic aortomyoplasty is an alternative to heart transplantation. The goal of our study was to evaluate the benefits of aortic counterpulsation obtained using dynamic aortomyoplasty in patients with heart failure refractory to pharmacologic treatment and with contraindications to heart transplant. METHODS: In this study, we compared the pre-operative and post-operative data of 15 selected patients who underwent dynamic thoracic aortomyoplasty. In this surgical technique, the right latissimus dorsi muscle flap is wrapped around the ascending aorta. This muscle flap was electrically stimulated during diastole, following a muscle-conditioning protocol, to obtain diastolic augmentation. At 12-month follow-up, we evaluated invasively and non-invasively the hemodynamic, clinical, and functional effects of aortomyoplasty. RESULTS: When comparing pre-operative data with 12-month follow-up data, we observed a significant decrease in the number of hospitalizations (p < 0.001) and in the New York Heart Association functional class (p < 0.001), and we observed significant improvement in the walking test (p < 0.001) and in peak oxygen consumption (p < 0.05). CONCLUSIONS: Dynamic, biologic, chronic counterpulsation of the aorta using a latissimus dorsi flap (dynamic aortomyoplasty) in selected patients with severe heart failure significantly improved hemodynamic parameters, heart functional data, and clinical functional class. A larger clinical experience with a longer follow-up would be useful in evaluating this technique's clinical relevance.     

Management of heart failure and coronary artery disease in patients with chronic kidney disease

Cardiovascular disease (CVD) is a major contributor to the mortality and morbidity of patients who suffer from chronic kidney disease (CKD). Heart failure and ischemic heart disease (IHD) are both highly prevalent in this population. The diagnosis of myocardial dysfunction is usually based on echocardiography. As in the general population, systolic dysfunction is treated with a combination of diuretics, renin-angiotensin system blockade, and beta-receptor antagonists. Diastolic dysfunction is best managed by eliminating the cause. Non-invasive tests for coronary artery disease (CAD) may be less reliable in patients with renal disease compared with nonuremic patients. Medical therapy of IHD in this population is generally similar to that for other patient groups, but surgical revascularization appears to carry a higher risk of complications with poorer clinical outcomes. The choice of revascularization procedure (coronary artery bypass grafting versus percutaneous transluminal angioplasty) should be based on the specific coronary anatomy of a given patient as well as a consideration of other comorbid factors.     

Pathophysiology of coronary artery disease and heart failure

Comorbid cardiovascular diseases can significantly increase the risk for perioperative morbidity and mortality. Increasing age of surgical populations and increasing invasiveness of surgical procedures further contribute to a significantly increased perioperative cardiovascular complication rate. Treatment of cardiovascular comorbidities and prevention of cardiovascular complications can decrease the perioperative risk. For detection and treatment of cardiovascular risk patients a thorough understanding of the underlying pathophysiology is of utmost importance. This article therefore reviews clinically relevant features of cardiovascular diseases with an emphasis on coronary artery disease and heart failure.     

Isoflurane: coronary blood flow and myocardial metabolism in patients with coronary heart disease

The effects of isoflurane on myocardial oxygen uptake, metabolism and coronary blood flow (argon washin-technique) were studied in 10 patients undergoing three-vessel coronary artery bypass surgery. All patients were men with stable angina and normal left ventricular function and were receiving maintenance doses of beta-receptor antagonists or calcium channel blocking drugs. Anaesthesia consisted of isoflurane and 50% nitrous oxide in oxygen. Measurements were performed and blood samples were taken with the patients awake, 20 min after induction of anaesthesia without surgical stimulation, and during sternotomy and sternal spread. End-tidal isoflurane concentrations averaged 0.4% after induction of anaesthesia and 1.5% during sternotomy. Isoflurane significantly decreased myocardial blood flow by 18% following induction of anaesthesia, while sternotomy increased myocardial blood flow to pre-induction levels. Induction decreased myocardial oxygen uptake by 32%, while sternotomy increased oxygen uptake by 21% vs post-induction values. Myocardial uptake of glucose, lactate, free fatty acids and pyruvate significantly decreased after induction and increased to pre-induction levels during sternotomy. Myocardial lactate production, indicating myocardial ischaemia, was observed in 1 patient after induction and in three patients during sternotomy; three additional patients demonstrated a marked reduction in myocardial lactate uptake after induction and during sternotomy. It is concluded that all changes in myocardial metabolism, oxygen uptake and coronary blood flow were the result of a decrease in haemodynamic load on the myocardium and reduced contractility, while the increase in these parameters during sternotomy was due to an increase in myocardial work.(ABSTRACT TRUNCATED AT 250 WORDS)     

Circulatory benefits of diastolic counterpulsation in an ischemic heart failure model after aortomyoplasty

OBJECTIVE: Aortomyoplasty is an experimental surgical procedure in which the latissimus dorsi muscle is wrapped around the thoracic aorta and stimulated to contract during diastole, providing diastolic counterpulsation. We hypothesized that aortomyoplasty could improve cardiac function in a chronic ischemic heart failure model, similar to the improvement seen with the intra-aortic balloon pump. METHODS: Six dogs (25-30 kg) successfully underwent aortomyoplasty followed by serial coronary microembolization. Ejection fraction decreased from 63.5% to 36.5%. Two weeks after the final microembolization, the muscle was conditioned for 4 months to achieve fatigue resistance. One year after aortomyoplasty, hemodynamic studies during 1 hour of aortomyoplasty and 1 hour of intra-aortic balloon counterpulsation determined mean diastolic aortic pressure, peak left ventricular pressure, and endocardial viability ratio for assisted and unassisted beats. Cardiac output, stroke volume, and parameters of cardiac function were also measured. RESULTS: Endocardial viability ratio increased by 23.8% +/- 7.9% (P =.001) with aortomyoplasty counterpulsation and by 22.7% +/- 12.9% (P =.021) with the intra-aortic balloon pump. Both aortomyoplasty and the intra-aortic balloon pump significantly increased mean diastolic aortic pressure and reduced peak left ventricular pressure. Improvements in cardiac function with aortomyoplasty and the intra-aortic balloon pump were similar. Cardiac output increased from 2.61 +/- 0.88 to 3.07 +/- 1.06 L/min (P =.006), and index of afterload decreased from 5.4 +/- 1.4 to 4.8 +/- 1.4 mm Hg/mL (P =.02) during 1 hour of aortomyoplasty counterpulsation. CONCLUSION: One year after the procedure, aortomyoplasty counterpulsation provided diastolic augmentation and improved cardiac performance similar to the improvement provided by the intra-aortic balloon pump in a chronic ischemic heart failure model. Aortomyoplasty has the potential to benefit patients with ischemic heart disease refractory to current therapies.     

Dynamic abdominal and thoracic aortomyoplasty in heart failure: assessment of counterpulsation.

BACKGROUND: Aortic counterpulsation, either biologic or mechanical, is a useful technique to support circulation during left ventricular dysfunction. METHODS: In this study we used an induced cardiac failure model in acute open chest sheep to compare hemodynamic improvements between thoracic and abdominal aortic counterpulsation. This was achieved with left latissimus dorsi and left hemidiaphragm muscle flaps. RESULTS: Thoracic and abdominal aortic counterpulsation in heart failure resulted in a significant improvement of hemodynamic parameters. Subendocardial viability index, defined as diastolic pressure-time index to systolic tension-time index, in thoracic and abdominal aortomyoplasty showed significant improvement (p<0.05) when cardiac assistance was performed by electrical stimulation of each muscle flap. A new counterpulsation index derived from diastolic and systolic areas beneath the aortic pressure curve was tested, obtaining a correlation coefficient with the subendocardial viability index of 0.758 (p<0.001). Values of subendocardial viability index and counterpulsation index showed minimal variability. CONCLUSIONS: Treatment of experimentally induced cardiac failure with dynamic abdominal aortic counterpulsation allows an effective hemodynamic improvement in open chest sheep. Furthermore, this diastolic arterial pressure augmentation could be evaluated through a new counterpulsation index derived from diastolic and systolic areas beneath the aortic pressure curve.     

Digital blood flow after radial artery harvest for coronary artery bypass grafting

BACKGROUND: Despite widespread use of radial artery as a bypass conduit in coronary artery bypass surgery, flow readjustment that takes place in the hands and fingers after the removal of the radial artery is poorly understood. METHODS: Using pulse volume recording plethysmography, a semiquantitative measurement of digital blood flow was carried out in 24 patients 7 days after harvesting of radial artery for coronary artery bypass grafting. Measurements taken from the fingers of the operated arms were evaluated and compared with those taken from the opposite or the control arms. RESULTS: Postoperatively, there was an overall decrease in blood flow to all the fingers of the operated arms. At the same time, there was evidence of redistribution of digital blood flow favoring the first two fingers over the last two, the same distribution pattern as seen in the fingers of the control arms. The pulse amplitude studies, likewise, showed a significant drop in all fingers of the operated arms, with the decrease most pronounced in the fourth and fifth fingers. None of the patients showed signs of digital ischemia postoperatively. CONCLUSIONS: The study showed that there was an overall decrease in digital blood flow after radial artery harvesting. The resulting blood supply by way of the remaining ulnar artery still provided more flow to the first two fingers over the last two fingers, indicating the existence of an autoregulatory mechanism operating to satisfy the physiologic needs of the fingers.     

Outcomes of coronary artery bypass grafting in patients with heart failure with a midrange ejection fraction

BackgroundCoronary artery bypass grafting (CABG) improves survival in patients with heart failure and severely reduced left ventricular systolic function (LVEF). Limited data exist regarding adverse cardiovascular event rates after CABG in patients with heart failure with midrange ejection fraction (HFmrEF; LVEF > 40% and < 55%).MethodsWe analyzed data on isolated CABG patients from the Veterans Affairs national database (2010-2019). We stratified patients into control (normal LVEF and no heart failure), HFmrEF, and heart failure with reduced LVEF (HFrEF) groups. We compared all-cause mortality and heart failure hospitalization rates between groups with a Cox model and recurrent events analysis, respectively.ResultsIn 6533 veterans, HFmrEF and HFrEF was present in 1715 (26.3%) and 566 (8.6%) respectively; the control group had 4252 (65.1%) patients. HFrEF patients were more likely to have diabetes mellitus (59%), insulin therapy (36%), and previous myocardial infarction (31%). Anemia was more prevalent in patients with HFrEF (49%) as was a lower serum albumin (mean, 3.6 mg/dL). Compared with the control group, a higher risk of death was observed in the HFmrEF (hazard ratio [HR], 1.3 [1.2-1.5)] and HFrEF (HR, 1.5 [1.2-1.7]) groups. HFmrEF patients had the higher risk of myocardial infarction (subdistribution HR, 1.2 [1-1.6]; P = .04). Risk of heart failure hospitalization was higher in patients with HFmrEF (HR, 4.1 [3.5-4.7]) and patients with HFrEF (HR, 7.2 [6.2-8.5]).ConclusionsHeart failure with midrange ejection fraction negatively affects survival after CABG. These patients also experience higher rates myocardial infarction and heart failure hospitalization.     

Increased night heart rate is associated with worse large artery elasticity in chronic kidney disease patients

Background

Chronic kidney disease (CKD) is associated with high overall and cardiovascular mortality. Numerous studies have reported that increased heart rate is a risk factor for all-cause mortality. We investigated the link between sleep heart rate and artery stiffness in CKD patients.

Methods

In a cross-sectional study, we enrolled 100 prevalent Chinese CKD patients (55 males, aged 52.5 ± 16.40 years). Heart rate was measured with an automatic system. Arterial stiffness was evaluated by using a calibrated tonometer.

Results

Large artery elasticity index (LAEI) was positively correlated with body mass index and hemoglobin but negatively associated with age and systolic blood pressure. Furthermore, LAEI was negatively associated with glomerular filtration rate (GFR) and sleep heart rate. In multivariate regression, LAEI was independently predicted by SBP, BMI, age, sleep heart rate, and gender. Adjusted R ² of the model was 0.486.

Conclusion

Elevated sleep heart rate is significantly associated with increased arterial stiffness in CKD patients. Further investigation is needed to explore the potential benefits of sleep heart rate lowering therapy in this patient group.     

Dopexamine increases internal mammary artery blood flow following coronary artery bypass grafting.

OBJECTIVE: Vasoactive agents and inotropes influence conduit-coronary blood flow following coronary artery bypass grafting (CABG). It was hypothesized that dopexamine hydrochloride, a dopamine A-1 (DA-1) and beta(2) agonist would increase conduit-coronary blood flow. A prospective randomized double blind clinical trial was carried out to test this hypothesis. DA-1 receptors have previously been localized to human left ventricle. METHODS: Twenty-six American Society of Anaesthesiology class 2-3 elective coronary artery bypass graft patients who did not require inotropic support on separation from cardiopulmonary bypass (CPB) were studied. According to a randomized allocation patients received either dopexamine (1 microg/kg per min) or placebo (saline) by intravenous infusion for 15 min. Immediately prior to and at 5,10 and 15 min of infusion, blood flow through the internal mammary and vein grafts (Transit time flow probes, Transonic Ltd.), heart rate, cardiac index, mean arterial pressure and pulmonary haemodynamics were noted. The data were analysed using multivariate analysis of variance. RESULTS: Low-dose dopexamine (1 microg/kg per min) caused a significant increase in mammary graft blood flow compared to placebo at 15 min of infusion (P=0.028, dopexamine group left internal mammary artery (LIMA) flow of 43.3+/-14.2 ml/min, placebo group LIMA flow at 26.1+/-16.3 ml/min). Dopexamine recipients demonstrated a non-significant trend to increased saphenous vein graft flow (P=0.059). Increased heart rate was the only haemodynamic change induced by dopexamine (P=0.004, dopexamine group at 85.2+/-9.6 beats/min and placebo group at 71.1+/-7.6 beats/min after 15 min of infusion). CONCLUSION: This study demonstrates that administration of dopexamine (1 microg/kg per min) was associated with a significant increase in internal mammary artery graft blood flow with mild increase in heart rate being the only haemodynamic change. Low-dose dopexamine may improve graft flow in the early post CABG period with minimal haemodynamic changes.     

Patient with pseudo-retrograde coronary flow in the normal right coronary artery and left circumflex artery: pitfall of retrograde coronary flow to detect coronary artery occlusion

A 75-year-old lady with hypertension and paroxysmal atrial fibrillation underwent echocardiography to evaluate cardiac function. Transthoracic Doppler echocardiography revealed retrograde coronary flow in the right coronary artery (RCA) and left circumflex artery (LCX). Computed tomographic coronary angiography demonstrated normal but tortuous coronary arteries. This tortuosity of the coronary arteries was thought be a cause of pseudo-retrograde coronary flow in the RCA and LCX. The present case demonstrates a pitfall of retrograde coronary flow for the detection of coronary artery occlusion in daily practice.