Seminars in Cardiothoracic and Vascular Anesthesia

Cardiac tumors are infrequent clinical entities with an autopsy frequency ranging from 0.001% to 0.030%. The occurrence of metastatic cardiac tumors has been reported a 100-fold more commonly than primary lesions. Three quarters of primary cardiac tumors are benign; approximately half of these are cardiac myxomas, and the rest are lipomas, papillary fibroelastomas, and rhabdomyomas. Among malignant primary cardiac tumors, the most reported are those histopathologically considered as undifferentiated, followed by angiosarcomas and leiomyosarcomas. Traditionally, cardiac tumors have been identified as curious autopsy findings resulting in a literature paucity of large clinical series, therefore, providing knowledge mostly based on case report collection. However, recent technological advances in noninvasive imaging modalities such as echocardiography and cardiac magnetic resonance imaging (MRI) have resulted in a rapid acquisition of real-time heart images with high spatial and temporal resolution and an excellent tissue characterization of the tumor. This consequent earlier, more frequent, and more complete assessment of cardiac tumors before significant symptoms develop has challenged cardiologists, cardiac anesthesiologists, and surgeons to create a tailored referral pattern and approach.

Heart failure is a disease of increasing prevalence around the world. The treatment options for patients suffering from this ailment range from pharmacologic to surgical. Heart failure, however, continues to harbor a dismal prognosis despite conventional treatments. The high mortality rate among this patient population has spawned interest in alternative therapies. Mechanical circulatory support has emerged as a treatment option for patients with refractory heart failure. Over the past years a number of studies have highlighted the effectiveness of left ventricular assist devices (LVAD’s) in improving patient’s outcomes. The technologies that support these devices have evolved and provide new opportunities to manage patients suffering from this debilitating disease. Heart transplantation continues to generate the most reproducible survival benefit to patients with advanced heart failure, but is limited by a lack of donors. It is therefore the goal of mechanical assist therapy to improve patient survival and quality of life in heart failure in light of the limitations of heart transplantation. In this article we examine the evolving utility of LVAD’s in the treatment of heart failure.

Perioperative spinal cord injury associated with thoracoabdominal aorta (TAAA) surgery is a devastating complication. With variable results, the intraoperative use of neurophysiologic monitoring has been employed for the diagnosis and prevention of spinal cord ischemia. We present a case report of a patient undergoing TAAA surgery with the use of evoked potential monitoring. Intraoperatively, both sensory and motor evoked potentials were utilized and consequently the patient experienced changes in monitoring consistent with a new neurologic deficit. However, postoperatively these changes in evoked potentials never manifested in neurologic injury. We examine the utility of neurophysiologic monitoring as it pertains to TAAA surgery.

Congestive heart failure represents a severe health condition with unfavourable long-term prognosis despite all the progress in pharmacological therapy of heart failure. Another therapeutic option is represented by mechanical cardiac support devices. Ventricular assist devices (VAD) constitute largest subgroup of these devices. Patients supported with VAD carry many considerations which are important for successful perioperative management of these patients for noncardiac surgery.

The general perioperative considerations include consultation with VAD management personnel, detailed assessment of end-organ dysfunction before surgery, appropriate antibiotic prophylaxis, deactivation of implantable cardioverter-defibrillator for the time of surgical procedure, and the choice between general and regional anesthesia. Intraoperative monitoring depends primarily on the type of blood flow generated by VAD. For devices generating pulsatile blood flow, standard monitoring arrangements are needed. In the patients supported by devices which provide nonpulsatile blood flow, pulse oximetry and noninvasive blood pressure measurement are not reliable monitoring methods, and placement of intra-arterial catheter is warranted. In all the patients supported with VAD, transesophageal echocardiography is extremely useful method for monitoring the function of VAD itself, and in the case of univentricular VAD for monitoring the function of nonsupported cardiac ventricle.

The most important issue in hemodynamic management of the patients with VAD is avoiding hypovolemia because it can cause inadequate VAD output with resulting low cardiac output and hypotension. All the patients with VAD need some degree of anticoagulation, and for noncardiac surgery the question of interrupting or decreasing the level of anticoagulation should be discussed among members of the caring team.

Neurological dysfunction and stroke following cardiac surgery and thoracic surgery requiring hypothermic circulatory arrest is a well-defined problem. The original studies in CABG patients identified risk factors, such as prior stroke and lower educational level. There is older evidence suggesting that higher perfusion pressures during cardiopulmonary bypass are helpful. Hyperthermia during rewarming on cardiopulmonary bypass and postoperative hyperthermia have been associated with adverse cognitive outcomes. Glucose management intraoperatively remains controversial, but most now advocate for moderate glucose control using insulin, if required. The subset of patients having thoracic aortic surgery requiring periods of aortic discontinuity are particularly problematic. A cerebral protection strategy should be determined, and this may include hypothermic circulatory arrest, selective cerebral perfusion, or retrograde cerebral perfusion. All of these techniques have been associated with good surgical outcomes, but there is little information on cognitive outcomes of thoracic aortic surgery.

Prior to cardiothoracic or vascular surgery, a patient's oral health is not usually a high priority for the surgical team. Yet, oral neglect often mirrors systemic disease and the need for proper dental care is often unmet. In the perioperative period, the presence of untreated decayed teeth and periodontal disease can result in a potent odontogenic infection with significant consequences. Patients can unknowingly present for such operations with undetected oral infections that can magnify the likelihood of an adverse outcome, increase costs, morbidity, and possibly mortality. Considering scheduling constraints and the urgency of the procedure, a pre-operative dental screening is suggested for patients who undergo elective cardiothoracic or vascular surgery, to ensure that any oral infection is diagnosed and definitively treated. Implementing such an effective and preventive approach can improve surgical outcome and overall patient health.

Although perioperative macrovascular events (eg, myocardial infarction, stroke) are readily evident, their absolute incidence remains relatively low. In contrast, microvascular dysfunction and its role in perioperative morbidity is not easily measured. Microvascular dysfunction is likely to have a greater impact on noncardiovascular complications (eg, wound healing and end-organ failure), through impaired perfusion, than that which is readily appreciated. Inflammation and oxidative stress, such as that induced by surgical trauma, disrupts endothelial homeostasis thereby decreasing the bioavailability of nitric oxide. This predisposes blood vessels to vasoconstriction, inflammation, leukocyte adhesion, thrombosis—factors that contribute to perioperative cardiovascular events at both macrovascular and microvascular level. Current clinical strategies applicable to the perioperative setting that improve microvascular health include preoperative exercise therapy, pharmacologic interventions (eg, statins, newer β-blockers) and attempts to stimulate mobilization and homing of bone marrow—derived endothelial progenitor cells. Many of these strategies are still in their infancy and large prospective trials that investigate the impact of these therapeutic options on postoperative outcome are eagerly awaited.

In the past decade, concern has been raised about the safety of anesthetic agents on the developing brain. Animal studies have shown an increase in apoptosis in the developing brain when exposed to N-methyl-D-asparate receptor blockers and/or gamma-aminobutyric acid receptor agonists that is related to the dose and duration of anesthetic agents. Whether these studies can be extrapolated to humans is being investigated. The Food and Drug Administration in 2007 convened an advisory committee to look at this issue. They found that the animal data available were inadequate to extrapolate to humans and determined that human studies were necessary. Human studies are underway but the challenge they face is how to delineate the effects of anesthesia from those of the underlying medical condition and surgery itself. At this time, we must continue to make decisions based on the known risks and benefits of anesthetics and apply it on an individual basis.

The article deals with acute respiratory distress-syndrome new classification which was developed at the V.A. Negovsky Research Institute of General Reanimatology (Moscow, Russia). This classification makes it possible to timely diagnose early stages of acute respiratory distress-syndrome by means of transpulmonary thermodilution method.

We retrospectively reviewed the first 14 patients who received preoperative paravertebral blockade prior to minimally invasive cardiac surgical procedures. The use of paravertebral blockade along with an anesthetic technique designed to facilitate rapid recovery allowed early extubation in the operating room or intensive care unit in all but one patient. Extubated patients leaving the operating room were comfortable. No postoperative respiratory complications occurred.

Thyroid or parathyroid surgery may be performed using general anesthesia or regional anesthesia. Ninety-five (95) patients underwent thyroid or parathyroid surgery using general anesthesia (n=64) or bilateral superficial cervical plexus block with sedation (n=31) and completed a postoperative questionnaire regarding the perioperative experience. Patients undergoing parathyroid surgery under regional anesthesia (n=24) were more likely to experience better energy levels (p=0.012) and earlier return to work (p=0.045) postoperatively. Overall, 96% of patients undergoing either type of surgery with either type of anesthetic reported satisfaction with the anesthetic.

Though relatively new, intraoperative neurophysiological monitoring (IONM) has become standard of care for many neurosurgical procedures. The use of IONM has substantially decreased the rate of paralysis after deformity surgery, and has been validated in cervical spine surgery, and thoracic and lumbar laminectomy ((1) (2), (3). The main modalities are: somatosensory evoked potentials (SSEPs), motor evoked potentials (MEPs), and electromyography (EMGs). Each test examines a functionally separate area of the spinal cord, which test is chosen depends on the location of the surgery and the patient’s preexisting injuries and deficits (6). Inhaled anesthetics decrease the waveform amplitude and increase latency, intravenous anesthetics have the same effect but to a lesser degree. Best anesthetic regimen for surgery involving intraoperative monitoring is controversial. Both inhaled and intravenous agents depress signal attainment, however for equal MAC concentrations inhaled agents cause more depression(11).

While studies have shown that halogenated agents and nitrous oxide do in fact depress MEP signals more than total intravenous anesthesia, less is known on the relationship between IONM and patient characteristics. Lo’s study documenting MEP attainment with 0.5 MAC was done in an otherwise healthy scoliosis population (12), and no study to date has analyzed signal attainment in correlation with patient characteristics and anesthetic technique. While it is clear that anesthetic technique is extremely important, certain patient characteristics appear to be more common in difficult to monitor patients. The identification of these characteristics would suggest to the anesthesiologist the need for a more stringent technique (TIVA) and avert surgical delay or cancellation due to inability to obtain baseline or worse- loss of intraoperative waveform and need for a Stagnara wake-up test. Our group at Mt. Sinai has retrospectively studied patient characteristics, anesthetic technique and attainment of neuromonitoring signals. Hypertension and diabetes are independent predictors of monitoring failure, and these are preferentially sensitive to inhalational agents. Age and weight are also predictors, but less significant.

In summary, neurophysiologic monitoring has evolved to be a consistent part of many procedures. The anesthesiologist should strive to understand the rationale behind monitoring and the basis of its utility. IONM has many implications for anesthetic technique and need for control of the physiologic milieu. With this knowledge the anesthesiologist can work together with the neuromonitoring team and surgeon to ensure patient safety during and after surgery.

Perioperative myocardial ischemia and infarction are not only major sources of morbidity and mortality in patients undergoing surgery but also important causes of prolonged hospital stay and resource utilization. Ischemic and pharmacological preconditioning and postconditioning have been known for more than two decades to provide protection against myocardial ischemia and reperfusion and limit myocardial infarct size in many experimental animal models, as well as in clinical studies (1-3). This paper will review the physiology and pharmacology of ischemic and drug-induced preconditioning and postconditioning of the myocardium with special emphasis on the mechanisms by which volatile anesthetics provide myocardial protection. Insights gained from animal and clinical studies will be presented and reviewed and recommendations for the use of perioperative anesthetics and medications will be given.

We sought to derive compliance curves of the trachea and esophagus. 16 fresh human cadavers were intubated tracheally and esophageally and cuff pressures measured at equal air volumes. Tracheal compliance was statistically less than esophageal compliance for volumes of 1, 2, and 3 mL of air, (p = 0.002, p = 0.008, and p = 0.006, respectively) but not so for volumes beyond that. This physical property is therefore not robust enough for detecting esophageal intubation.

Stroke is the leading cause of long-term disability in the United States. Hence immediate diagnosis must be made by CT or MRI and therapy instituted rapidly. Anesthesiologists must be aware of the concept of “penumbra” and maintain collateral flow. Blood pressure management is crucial. American Stroke Council recommends blood pressure reduction if systolic >220 mm Hg and diastolic >120 mm Hg. However if thrombolytic therapy is being used, blood pressure must be reduced to systolic <180 mmHg and diastolic < 105 mm Hg. Cerebral autoregulation may be dysfunctional in ischemic brain. Anesthesia management requires control of the airway to prevent aspiration, maintain adequate oxygenation and ventilation, and management of raised intra cranial pressure. Complications of intra-arterial thrombolysis include intracerebral hemorrhage. Frequent neurological exams are warranted. Extensive cerebral swelling may require hemi craniectomy. “Time is Brain” hence urgent thrombolysis is the key to a good outcome.

Many women in the United States receive analgesia for labor and delivery. The ideal labor analgesic technique would confer complete pain relief without side effects. The analgesic technique would not cause any lower extremity motor blockade nor interfere with the progress or course of labor and would be sufficiently flexible to produce anesthesia for instrumental or cesarean deliveries. Furthermore, the baby would be vigorous at birth. Modern obstetric analgesia techniques and medications achieve these goals. This article reviews current labor analgesia techniques and medications used during labor and delivery.

Risk stratification in cardiac surgery is based on different models. The great majority of these models derives from a logistic regression equation, and the resulting risk score attributes a specific value to a number of risk factors. However, the number, definition, and type of risk factors included in each risk score greatly varies. Some of the existing risk models include up to 15-20 risk factors. However, it has been demonstrated that for elective patients a simple risk model based on just three factors (age, creatinine, and ejection fraction) has the same level of accuracy and a much better calibration that more complex models. The main deficiency of all the risk models is that they cannot take into consideration the presence of extreme risk conditions which have a very low prevalence, but which are accompanied by a very high operative mortality rate.

Hemodynamically significant perivalvular regurgitation affects about 1.5% of all prosthetic valve implants. Reoperation carries increased risk—especially in the setting of concomitant comorbidities of left ventricular dysfunction, prior coronary artery bypass grafts, renal dysfunction, and advanced age. Transcatheter closure of the perivalvular regurgitant channel using a variety of occluders has been available for several years; however, recent improvements in technology and technique have made this therapy more effective and available to a wider group of patients. This article describes the recent advances and the state of the art of this therapy.

Heparin-induced thrombocytopenia (HIT) is an antibody-mediated reaction caused by exposure to heparin that can lead to devastating thrombotic complications. HIT usually occurs 5 to 10 days after exposure to heparin but can happen more rapidly to patients who are reexposed to heparin within 100 days. The hallmark of this disorder is a sudden drop in platelet count of greater than 50%. Once HIT is suspected the heparin must be immediately discontinued and an anticoagulant (direct thrombin inhibitor or heparinoid) started. For patients presenting for cardiac surgery and cardiopulmonary bypass that have a history of HIT and positive antibodies a direct thrombin inhibitor such as lepirudin, argatroban or bivalirudin must be used in lieu of heparin.

Administering anesthesia to pediatric patients can always be challenging, especially for the nonpediatric anesthesiologist. Certain types of pathology and non—operating room settings can make these cases even more of a challenge, even for the most skilled pediatric anesthesiologist. This article will outline a few of these special situations, and attempt to give the practitioner an approach to the management of these patients.