Echocardiographic and angiographic evaluation of left ventricular function during percutaneous transluminal aortic valvuloplasty

[Anesthesia with transfemoral and transapical aortic valve implantation. Periinterventional management and hemodynamic observations]

Percutaneous transfemoral and transapical aortic valve implantations are novel procedures that often confront the anesthesiologist with bigger challenges than surgical aortic valve replacements using cardiopulmonary bypass. Due to old age and the presence of severe comorbidities including pulmonary vascular hypertension, most patients have a very high risk. Individual comorbidities and their severity are as important for the choice of the anesthetic technique as pharmacological cardiovascular therapy and communication during the respective phases of the intervention. Since severe hemodynamic alterations (cardiogenic shock, coronary ischemia, arrhythmias) and potential interventional complications (bleeding, ventricular and vascular injury) may occur, the authors routinely perform an extended cardiovascular monitoring. General endotracheal anesthesia may be advantageous even for transfemoral valve implantation and was not associated with a worse outcome. Following valve implantation a substantial increase in cardiac index, but also of all filling pressures was measured. Anesthesia coverage time for the first 100 cases averaged 263 min (+/- 96) for transfemoral and 297 (+/- 78) for transapical valve implantation, which appears greater than for conventional aortic valve replacement surgery, but it decreased significantly for transfemoral valve implantation over the course of interventions. Accordingly, the anesthesiologist, besides providing anesthesia and managing the airway, assumes responsibility for invasive cardiopulmonary monitoring, cardiovascular pharmacotherapy tailored to intervention phases, and "troubleshooting" in the event of complications for these still developing interventions.

[Transcatheter-based aortic valve implantation. Present and future technologies]

The calcified aortic stenosis is the dominating valve disease. Patients affected are most common elderly people in the 8th or 9th decade of their life who often show associated comorbidities like reduced left ventricular function, impaired renal function, pulmonary hypertension, and further diseases (diabetes mellitus, stroke, chronic obstructive pulmonary disease). In many cases perioperative morbidity and mortality are too high for surgical valve replacement and patients are rejected. Nevertheless, prognosis of aortic stenosis is worse, if the typical symptoms like dyspnea on exertion, syncope, and angina occur. The transcatheter aortic valve implantation is an alternative treatment for this particular group of patients. The aortic valve bioprosthesis consists of a balloon-expandable stent or a self-expandable frame, in which a valve of bovine or porcine pericardium is incorporated. The implantation is performed by retrograde access via the femoral artery; the balloon-expandable prosthesis can also be implanted by transapical approach. Alternatively, the subclavian artery is chosen for access. More frequently, the implantation is performed in analgosedation with the patient awake that favors the transfemoral approach. A further reduction of the available prosthesis and new types of valves which are under current experimental tests and clinical evaluation contribute to this development.

The complexity of parathyroid hormone-related protein signalling

Our understanding of the mode of action of parathyroid hormone-related protein (PTHrP) has changed profoundly during the last decade. Most PTHrP activities are mediated by membrane receptors through autocrine/paracrine pathways. However, both endogenous and exogenous PTHrP also appear to have intracrine effects through translocation into the nucleus. The present review proposes unconventional PTHrP signalling, based on novel clues. First, PTHrP binding to its membrane receptor triggers internalization of the whole complex, mediated by beta-arrestin. There is growing evidence that the receptor and arrestin are the effectors of biological responses, rather than the ligand (or in addition to the ligand). Second, the existence of putative PTHrP targets within the cytoplasm is beginning to be supported. Recent findings of interactions between a COOH-terminus of PTHrP and beta-arrestin and between the PTHrP receptor and 14-3-3 proteins represent the starting point for identification of intracellular partners of both the hormone and its receptor.

[Interventions in congenital heart disease and their sequelae in adults]

The advancements of cardiac surgery over the last decades led to larger numbers of patients with operated congenital heart diseases surviving into adulthood. In Germany it is estimated that over 120,000 adults have operated congenital heart diseases. Five to 7% of them will need yearly hospital admissions. Interventional procedures are additional tools used to treat these patients with various sequelae or residua (Table 1). In the following review we concentrate on 2 different interventional procedures: dilatation and stent implantations for treatment of stenosis and the different devices used for the closure of shunt lesions. For congenital valvular pulmonary stenosis, balloon dilatation is the therapy of choice regardless the age of the patient. Stent implantation for the treatment of peripheral pulmonary stenosis (e.g., after previous systemic pulmonary shunts) can decrease the need for redo surgery, which is accompanied with increased risk. Stent implantations proved also to be useful to treat stenoses after Mustard patch in patients with transposition of the great arteries, after Fontan procedures or dealing with the rare pulmonary venous stenosis. In contrast, dilatation of bioprosthesis and conduit stenosis are not promising. Balloon dilatation of valvular aortic stenosis is an accepted therapy in childhood up to adolescents. Table 2 compares a surgical series including many infants with critical aortic stenosis with a series of balloon dilatation in children and another one in adults regarding lethality, complications, and results. Table 3 illustrates the immediate and late results of balloon dilatation of aortic coarctation in 3 different studies. The high recurrence rate in infants made clinicians refrain from taking this age group for balloon dilatation. In children and adult patients, good results are reported (75% reduction of gradients). The complication rate is low (2.3 to 3.3%) and aneurysm formation rate seldom (1 to 7%). Stenosed aorto-pulmonary collaterals will rarely need balloon dilatation. Surgical closure of atrial septal defect is a low risk procedure with a very low rate of residual shunts (2%). Of the 5 available devices for transcatheter closure of atrial septal defect Type II, only 2 occluders are in use in Germany, the Clamshell and the Amplatzer device. The largest clinical studies of the different systems, their efficacy, complications and residual shunt rate are presented in Table 4. For the deployment of these occluders a TEE is always needed. There are many more systems in clinical use to close the patent arterial duct (PDA) (Table 5). The Ivalon plug as well as the Rashkind device have probably only historical value. Different types of coils (Gianturco, Cook detachable, PFM) are now in use worldwide. The reason for their widespread use, besides their easy application, is the fact that most coils are relatively cheap and need only small sheaths for deployment. Their further evaluation identified a residual shunt rate of 5% as well as a number of complications (embolization, hemolysis, stenosis of the left pulmonary artery) in 0 to 6%. For the large PDA the Amplatzer device has recently been introduced. An additional indication for the use of the different occluding devices are aorto-pulmonary collaterals, venovenous fistulae, pulmonary or coronary artery fistulae. Aorto-pulmonary collaterals are often associated with complex cardiac lesions and occasionally appear after palliative procedures. An excellent cooperation between adult and pediatric cardiologists is needed in order to offer the group of adults with congenital heart diseases an adequate and comprehensive management.