Clinical usefulness of end-tidal CO2 profiles during incremental exercise in patients with chronic thromboembolic pulmonary hypertension.

INTRODUCTION: Great ventilation to carbon dioxide output (ΔV˙E/ΔV˙CO2) and reduced end-tidal partial pressures for CO2 (PetCO2) during incremental exercise are hallmarks of chronic thromboembolic pulmonary hypertension (CTEPH) and idiopathic pulmonary arterial hypertension (IPAH). However, CTEPH is more likely to involve proximal arteries, which may lead to poorer right ventricle-pulmonary vascular coupling and worse gas exchange abnormalities. Therefore, abnormal PetCO2 profiles during exercise may be more prominent in patients with CTEPH and could be helpful to indicate disease severity. METHODS: Seventy patients with CTEPH and 34 with IPAH underwent right heart catheterization and cardiopulmonary exercise testing. According to PetCO2 pattern during exercise, patients were classified as having an increase or stabilization in PetCO2 up to the gas exchange threshold (GET), an abrupt decrease in the rest-exercise transition or a progressive and slow decrease throughout exercise. A subgroup of patients with CTEPH underwent a constant work rate exercise test to obtain arterial blood samples during steady-state exercise. RESULTS: Multivariate logistic regression analyses showed that progressive decreases in PetCO2 and SpO2 were better discriminative parameters than ΔV˙E/ΔV˙CO2 to distinguish CTEPH from IPAH. This pattern of PetCO2 was associated with worse functional impairment and greater reduction in PaCO2 during exercise. CONCLUSION: Compared to patients with IPAH, patients with CTEPH present more impaired gas exchange during exercise, and PetCO2 abnormalities may be used to identify more clinically and hemodynamically severe cases.

Vasoplegic syndrome after open heart surgery.

BACKGROUND: A new form of postperfusion manifestation is detailed, a vasoplegic syndrome presenting in the postoperative period after cardiopulmonary bypass (CPB) heart surgery. METHODS: This retrospective study included sixteen patients who underwent cardiovascular surgery using CPB and exhibited clinical and hemodynamic features compatible with vasoplegic syndrome. The technique of CPB was hypothermic (28 degrees C) in 15 and normothermic in 1 patient, and hypothermic blood cardioplegia was employed in all patients, except 1. The mean CPB time was 121 minutes, ranging from 80 to 210 minutes. RESULTS: The patients presented a severe feature comprising hypotension, tachycardia, normal or elevated cardiac output, low systemic vascular resistance and decreased filling pressures. Fluid administration alone was not capable of restoring hemodynamic parameters. Physical examination revealed normal capillary filling at the extremities although oliguria and hypotension were observed. These patients needed a high dosage of vasoconstrictor drugs (norepinephrine) for blood pressure control but even high dose norepinephrine did not produce the classical situation of cool extremities and weak peripheral pulses, with increased morbidity and mortality. Severe systemic complications could develop if the vasoplegic syndrome persisted 36-48 hours after its onset. All patients, except 3, presented associated postoperative complications and 4 patients died. The characteristics of vasoplegic syndrome are similar to those observed in septic shock, where the alterations are mediated by cytokines and tumor necrosis factor-alpha. CONCLUSIONS: The appearance of vasoplegic syndrome augmented operative morbidity with a consequent increased risk to the patient in the early postoperative period.

[Myocardial revascularization through small left anterior minithoracotomy]. / Revascularização do miocárdio através de minitoracotomia esquerda.

PURPOSE: To analyze the results of myocardial revascularization through small left anterior thoracotomy utilizing the left thoracic internal artery (LTIA) to left anterior descending coronary artery (LAD) without cardiopulmonary bypass, in order to simplify the operative procedure. METHODS: From September/95 till August/96 we operated on 45 patients with lesions in LAD or LAD and diagonal arteries that were revascularized with an anastomoses of the LTIA to LAD or LAD and diagonal as composite grafts, through left anterior small thoracotomy. In the second postoperative day 43 out of 45 patients were restudied with arteriography and/or transthoracic echocardiography that showed excellent patency in 39 of them. RESULTS: Six patients with obstruction or stenoses were reoperated through median sternotomy without complications. We did not observe flow through intercostal arteries in these restudies except in cases of obstructed anastomosis, showing that it is not necessary to ligate these branches. We observed too, excellent correlation between angiographic patterns and diastolic flows detected in the thoracic internal artery with transthoracic echocardiography. CONCLUSION: These initial results suggest that this approach may be good to a subset of patients with lesions in LAD and/or diagonal arteries and if associated with complementary angioplasties of other coronary arteries may be the best choice of invasive treatment of coronary insufficiency in a near future.

Coronary artery bypass grafting without cardiopulmonary bypass.

BACKGROUND: Coronary artery bypass grafting without cardiopulmonary bypass is now an accepted technique of myocardial revascularization. We herein report our total experience with this procedure. METHODS: In a consecutive series of 8,751 patients operated on in our institution for coronary artery disease from 1981 to 1994, 1,274 patients received coronary artery bypass grafting without cardiopulmonary bypass. RESULTS: Results indicate that the operation can be performed with an acceptable mortality (2.5%), and that all types of arterial conduits can be used. Most commonly the left anterior descending and right coronary arteries were bypassed. The incidence of arrhythmias and of pulmonary and neurologic complications were significantly lower in this group of patients compared with patients receiving coronary artery bypass grafting with cardiopulmonary bypass. Most importantly, there was decreased cost when the procedure was used because no extracorporeal circulation, cardioplegia sets, or other cannulas were used. CONCLUSIONS: We conclude that the continuing use of coronary artery bypass grafting without cardiopulmonary bypass is justified and that, with proper selection of patients, the procedure is safe and cost-effective.