[Surgical treatment of chronic thromboembolic pulmonary hypertension]. / Traitement chirurgical de la maladie thromboembolique pulmonaire chronique.

Chronic thromboembolic pulmonary hypertension is a condition that has long remained in the shadows, a kind of orphan disease, because of the lack of any curative treatment. The renewal of interest by pulmonary specialists, cardiologists and thoracic surgeon is due to the development over the past 20 years of major new treatments: lung transplantation, continuous prostacyclin infusion, and pulmonary endarterectomy, in chronological order. Most patients with postembolic pulmonary arterial hypertension (PEPAH) in a sufficiently proximal location can benefit from curative surgical treatment by bilateral endarterectomy of the pulmonary arteries. This complex surgery, performed under deep hypothermic circulatory arrest, clears out the pulmonary vascular bed down through its subsegmental branches and results in a frank reduction in pulmonary vascular resistance and normalization of cardiopulmonary function. It is a curative procedure with a perioperative mortality rate less than 7% and a definitive result, unlike pulmonary and cardiopulmonary transplantation, which have a postoperative mortality rate of 20% and a 5-year survival rate of 50%. It is difficult to recognize the postembolic nature of pulmonary hypertension because there is no known history of venous thrombosis or embolic phenomena in more than 50% of cases. Diagnosis is based on the presence of mismatched segmental defects in the radioisotopic ventilation-perfusion scanning. To be accessible to endarterectomy, lesions must involve the main, lobar, or segmental arteries. When conducted by experienced operators according to specific protocols, pulmonary (frontal and lateral views of each lung) and multislice CT angiography optimize assessment of the lesion site. When the pulmonary vascular resistance evaluated by catheterization is correlated with the anatomical obstruction visible on the images, pulmonary endarterectomy has a mortality rate below 4% and offers the patient a substantial chance to regain normal cardiorespiratory function. In cases of pulmonary arterial hypertension due to older embolisms, major arteriolitis occurs in the nonobstructed areas and aggravates the pulmonary hypertension, which may become suprasystemic. The endarterectomy mortality rate is then higher, and in specific cases justifies preoperative medical treatment. Pulmonary or cardiopulmonary transplantation is indicated in this disease only when the lesions are too distal and thus inaccessible to endarterectomy.

Beyond hyperkalemia: beta-blocker-induced cardiac arrest for normothermic cardiac operations.

BACKGROUND: Four experimental protocols were carried out to assess the ability of esmolol to induce and maintain reversible cardiac arrest under continuous normothermic (37 degrees C) perfusion. METHODS AND RESULTS: In the first protocol, 8 perfused rat hearts were subjected to 20, 60, 90, and 120 minutes of esmolol arrest, after which positive and negative first derivative of pressure, heart rate, left ventricular developed pressure, and left ventricular end-diastolic pressure were evaluated. Arrest was achieved 45 to 60 seconds after beginning the infusion of esmolol. Mechanical arrest was achieved before electrical arrest. In the second protocol, dose-response curves were obtained using isolated (Langendorff) rat and rabbit (n = 6) hearts. The concentrations of esmolol varied from 0.084 to 6.7 mmol/L and from 0.12 to 1.45 mmol/L in the rat and rabbit heart experiments, respectively. In the third protocol, the effects of 20 minutes of normothermic (37 degrees C) ischemia on the function of isolated rat hearts perfused with esmolol-containing Krebs solution were compared with those using high-potassium (25 mmol/L) Krebs solution. Group A subjects (n = 9) received the ischemic injury after being perfused (and arrested) for 20 minutes with either esmolol or potassium (KCl, 25 mmol/L). Group B subjects (n = 10) received the same ischemic insult before being perfused with either esmolol or potassium. Esmolol-treated hearts showed better recovery than those receiving potassium, in terms of +/- dP/dt (p < 0.01), left ventricular systolic pressure (p < 0.01), and left ventricular developed pressure (p < 0.009). Finally, the fourth protocol was done to evaluate the effects of esmolol in a clinically relevant experimental model. Pigs were divided into esmolol (n = 6) and potassium (n = 5) groups and subjected to normothermic cardiopulmonary bypass and a 1-hour period of cardiac arrest. Twenty minutes after stopping infusion of the cardioplegic agents, all animals were weaned off bypass. There were no statistically significant differences between the groups. CONCLUSIONS: Esmolol hydrochloride can be used as effectively as potassium for inducing and maintaining predictable and reversible cardiac arrest during normothermic cardiac operations.

[Surgical treatment of post-embolism pulmonary hypertension]. / Traitement chirurgical de l'hypertension artérielle pulmonaire post-embolique.

Pulmonary hypertension is a serous condition which, after a long history as an orphan disease, has raised renewed interest due to the development of efficacious therapeutic options including lung transplantation and continuous infusion of prostacycline. Bilateral endarteriectomy of the pulmonary arteries is another possibility for post-embolism pulmonary hypertension. The procedure is complex and must be performed in conditions of cardiac arrest and deep hypothermia but, unlike transplantation, provides definitive cure. Recognizing the post-embolic nature of pulmonary hypertension is not simple because old episodes of venous thrombosis or embolus migration are not found in 50% of patients. Segmentary defects on the perfusion scintigraphy contrasting with the homogeneous respiratory scintigraphy is the primary diagnostic feature. Lesions must be located in a main trunk or at the origin of lobular or segmentary branches to be accessible to endarteriectomy. An antero-posterior and lateral angiogram of each lung and a multiple-array helicoidal angioscan performed with a precise protocol by an experienced team are needed to identify the localization of the lesions. If the pulmonary resistance determined at right catheterism is correlated with anatomic obstruction, the risk of mortality of pulmonary endarteriectomy is low, offering patients a significant chance for normal or nearly normal cardiorespiratory function.

Chronic thromboembolic pulmonary hypertension.

Pulmonary arterial hypertension is a severe disease that has been ignored for a long time. However, over the past 20 yrs chest physicians, cardiologists and thoracic surgeons have shown increasing interest in this disease because of the development of new therapies, that have improved both the outcome and quality of life of patients, including pulmonary transplantation and prostacyclin therapy. Chronic thromboembolic pulmonary arterial hypertension (CTEPH) can be cured surgically through a complex surgical procedure: the pulmonary thromboendarterectomy. Pulmonary thromboendarterectomy is performed under hypothermia and total circulatory arrest. Due to clinically evident acute-pulmonary embolism episodes being absent in > 50% of patients, the diagnosis of CTEPH can be difficult. Lung scintiscan showing segmental mismatched perfusion defects is the best diagnostic tool to detect CTEPH. Pulmonary angiography confirms the diagnosis and determines the feasibility of endarterectomy according to the location of the disease, proximal versus distal. The technique of angiography must be perfect with the whole arterial tree captured on the same picture for each lung. The lesions must start at the level of the pulmonary artery trunk, or at the level of the lobar arteries, in order to find a plan for the endarterectomy. When the haemodynamic gravity corresponds to the degree of obliteration, pulmonary thromboendarterectomy can be performed with minimal perioperative mortality, providing definitive, excellent functional results in almost all cases.