13. Which is preferred: surgical or medical management of descending dissections?

Show answer

* Initial surgical managementApproximately 25% of patients initially treated medically need an operation eventually.
* Operative mortality is much lower today (20%) than in the past.
* Medical management has the same in-hospital mortality (20%).

* Initial medical managementThis avoids unnecessary operation and its attendant cost and complication rate.

14. What is the preferred management of aortic insufficiency in ascending dissections?

Show answer

* Replacement of aortic valveEasy (valved conduits now available)
* Eliminates aortic insufficiency completely
* Should be done in patients with Marfan syndrome

* Repair of aortic valveWith native valve reconstruction, when done correctly, the need to replace the valve at a later time is only 10%.
* Avoids need for anticoagulation, which is necessary when a mechanical valve is used to replace the aortic valve.

15. What is the preferred repair of descending dissections?

Show answer
1. Partial left atrial-to-femoral artery bypass
For:

* Allows unloading of the heart
* Allows distal perfusion to avoid visceral ischemia
* Allows as much time as needed to complete anastomosis

Against: requires heparinization
2. Simple aortic cross-clamping
For: Fast
Against: Placement of the graft has to be done in < 30 minutes or the complication rate, particularly paraplegia, increases significantly.

16. Are there any other alternatives for the treatment of patients with acute aortic dissection?

Show answer
Although in the early stages of development, the use of endovascular stents may prove to be a useful treatment option. The use of these stents is still considered experimental, and the long-term results are not known.

References
WEB SITE
http://www.acssurgery.com
BIBLIOGRAPHY
1. Barron DJ, Livesey SA, Brown IW, et al: Twenty-year follow-up of acute type A dissection: The incidence and extent of distal aortic disease using magnetic resonance imaging. J Card Surg 12:147-159, 1997. Medline Similar articles
2. Cigarroa JE, Isselbacher EM, DeSanctis RW, Eagle KA: Diagnostic imaging in the evaluation of suspected aortic dissection. Old standards and new directions. N Engl J Med 328:35-43, 1993. Medline Similar articles Full article
3. Glower DD, Fann JI, Speier RH, et al: Comparison of medical and surgical therapy for uncomplicated descending aortic dissection. Circulation 82(suppl IV):39-46, 1990.
4. Khan IA, Nair CK: Clinical, diagnostic, and management perspectives of aortic dissestion. Chest 112:311-328, 2002. Full article
5. Nienaber CA, von Kodolitsch Y, Nicolas V, et al: The diagnosis of thoracic aortic dissection by noninvasive imaging procedures. N Engl J Med 328:1-9, 1993. Medline Similar articles Full article
6. Okita Y, Takamoto S, Ando M, et al: Mortality and cerebral outcome in patients who underwent aortic arch operations using deep hypothermic circulatory arrest with retrograde cerebral perfusion: No relation of early death, stroke, and delirium to the duration of circulatory arrest. J Thorac Cardiovasc Surg 115:129-138, 1998. Medline Similar articles
7. Safi HJ, Miller CC, Reardon MJ, et al: Operation for acute and chronic aortic dissection: Recent outcome with regard to neurologic deficit and early death. Ann Thorac Surg 66:402-411, 1998. Medline Similar articles Full article
8. Wheat MW Jr, Palmer RF, Bartley TB, Seelman RC: Treatment of dissecting aneurysms of the aorta without surgery. J Thorac Cardiovasc Surg 50:364-373, 1995.

1. Why is the term dissecting aortic aneurysm really incorrect?

Show answer
The correct term should be dissecting aortic hematoma because the lesion is not an aneurysm. Blood dissects between the middle and outer layers of the media and adventitia of the aorta (specifically, there does not need to be an intimal tear, although there usually is).

2. When should the diagnosis be entertained?

Show answer
Suspicion is the most important factor because no one feature is common to patients presenting with aortic dissections. In any patient who presents with severe knifelike, ripping chest and back pain, the diagnosis of aortic dissection should be considered.

3. After the diagnosis is entertained, how should the patient be managed?

Show answer
Two thirds of patients are hypertensive, so blood pressure must be controlled. The other diagnosis to be strongly considered is acute myocardial infarction (MI). An electrocardiogram often rules out MI, but some aortic dissections tear off a coronary artery; thus, both acute infarction and aortic dissection occur concurrently (this patient group is in big trouble).

4. What is the most significant diagnostic clue on physical examination?

Show answer
A new aortic valvular diastolic murmur, indicating aortic valvular regurgitation caused by distortion of the valve structure by the mural hemotoma. In addition, the dissecting hematoma can encircle the lumen or actually cleave the takeoff of the subclavian or femoral vessels, resulting in the loss of pulses. Neurologic findings, including paraplegia and hemiplegia, may also be present because of similar flap occlusion of the great vessels.

5. Which chest radiograph findings are helpful in diagnosis?

Show answer
Widened mediastinum and loss of aortic knob silhouette-a hematoma surrounding the aorta makes the aortic outline blurry-are helpful findings.

6. How is the diagnosis confirmed? What are the best diagnostic studies?

Show answer
The literature reports the high accuracy of transesophageal echocardiography (TEE) and computed tomography angiography (CTA) in the diagnosis of aortic dissections. Some institutions rely solely on one of these diagnostic tool (both studies are operator dependent). However, the aortogram is still the gold standard, but it requires more time. If time allows and the patient is stable, an aortogram should be obtained to confirm the diagnosis, type of dissection (ascending versus descending), status of the aortic valve, and status of the coronary arteries. In fact, the modalities may be complementary: whereas the TEE or CTA confirms the diagnosis, the aortogram defines location and evaluates the status of the aortic valve and coronary arteries.

7. What are the types of dissection?

Show answer
The following classification has both therapeutic and prognostic value:

* Ascending (type A) involves only the ascending or both the ascending and descending aorta.
* Descending (type B) involves only the descending aorta.

8. Who cares whether a dissection involves the ascending (type A) or descending (type B) aorta?

Show answer
Ascending dissections require early surgical correction to avoid extension into the coronary or carotid arteries, rupture into the pericardium (tamponade), or both.
Descending dissections do not involve the ascending aorta and may be managed medically or surgically (see Controversies).

9. What is the key to medical management?

Show answer
The blood pressure (BP) should be lowered to 100-110 mmHg (systolic) with a combination of sodium nitroprusside and propranolol. Propranolol is particularly important because it decreases the contractility of the myocardium (dp/dt), thereby decreasing the shearing force that prevents propagation of the dissection down the aorta. Conceptually, the BP should be lowered as much as possible, but the patient must continue to perfuse the end organs (i.e., make urine).

10. What are the principles and advantages of surgical management?

Show answer

1. Ascending dissectionTo close off the hematoma by obliterating the most proximal intimal tear
2. To restore competency of the aortic valve
3. To restore flow to any branches of the aorta that have been sheared off and receive blood flow from a false lumen
4. To protect the heart during these maneuvers and to restore coronary blood flow if a coronary artery has been sheared off
5. To look for tears in the transverse aortic arch

Technique: Use of deep hypothermia circulatory arrest with or without retrograde cerebral perfusion is in vogue at present. This technique allows the arch to be inspected and the distal anastomosis of the Dacron graft to be sewn accurately to the distal ascending aorta in an open fashion. Whether to replace or repair the aortic valve is controversial.

1. Descending dissectionTo close off the hematoma by obliterating the most proximal intimal tear
2. To restore blood flow to branches of the aorta fed by the false channel

Technique: Surgery is performed using partial cardiopulmonary bypass, or the “clamp and run” technique, in which the aorta is cross-clamped and the graft is sewn in as fast as possible (see Controversies).
KEY POINTS: DISSECTING AORTIC ANEURYSM

1. The correct term should be dissecting aortic hematoma because the lesion is not an aneurysm.
2. A new aortic valvular diastolic murmur, indicating aortic valvular regurgitation caused by distortion of the valve structure by the mural hematoma.
3. Ascending dissections require early surgical correction to avoid extension into the coronary or carotid arteries, rupture into the pericardium, or both.
4. Descending dissections may be managed medically; blood pressure should be lowered to 100-110 mmHg with a combination of sodium nitroprusside and propranolol.

11. What are the operative complications?

Show answer

* Hemorrhage (20%): very common because of the use of heparin and the poor quality of aortic tissue (like wet Kleenex)
* Renal failure (20%)
* Pulmonary insufficiency (30% higher in repair of descending dissections)
* Paraplegia: often presents before operation; as a surgical complication, it usually occurs only with descending dissections (11%)
* Acute MI or low cardiac output (30%)
* Bowel infarction (5%)
* Death (15%): higher for acute than chronic dissections and higher for repair of ascending dissections

12. What are the long-term results?

Show answer
Of patients who survive the operation, two thirds die within 7 years because of comorbid cardiac and cerebrovascular disease.

1. What is a solitary pulmonary nodule?

Show answer
A solitary pulmonary nodule or “coin lesion” is < 3 cm and is discrete on chest radiograph. It is usually surrounded by lung parenchyma.

2. What causes a solitary pulmonary nodule?

Show answer
The most common causes of a pulmonary nodule are either neoplastic (carcinoma) or infectious (granuloma). Pulmonary nodules may also represent lung abscess, pulmonary infarction, arteriovenous malformations, resolving pneumonia, pulmonary sequestration, hamartoma, and others. As a general rule of thumb, likelihood of malignancy is proportionate to the patient’s age. Thus, whereas lung cancer is rare (although it does occur) in 30-year-old individuals, in 50-year-old smokers, the chances of malignancy may be as high as 50-60%.

3. How does a solitary pulmonary nodule present?

Show answer
Typically, a solitary nodule is picked up incidentally on routine chest radiograph. In several large series, more than 75% of lesions were surprise findings on routine chest radiograph. Fewer than 25% of patients had symptoms referable to the lung. Solitary nodules are now seen on other sensitive imaging tests such as helical computed tomography (CT).

4. How frequently does a solitary pulmonary nodule represent metastatic disease?

Show answer
Fewer than 10% of solitary nodules represent metastatic disease. Accordingly, an extensive workup for a primary site of cancer other than the lung is not indicated.

5. Can a tissue sample be obtained by fluoroscopic or CT-guided needle biopsy?

Show answer
Yes, but the results do not change the treatment. If the needle biopsy tissue indicates cancer, the nodule must be removed. If the needle biopsy is negative for cancer, the nodule must still be removed. Positron emission tomography (PET) is 90% sensitive in identifying malignant tumors.

6. Are radiographic findings important?

Show answer
Only relatively. The resolution of modern CT scanners allows the best identification of characteristics that suggest cancer:

1. Indistinct or irregular spiculated borders of the nodule.
2. The larger the nodule, the more likely it is to be malignant.
3. Calcification in the nodule generally is associated with benign disease (the opposite of breast cancer). Specifically, whereas central, diffuse, or laminated calcifications are typical of a granuloma, calcifications with more dense and irregular “popcorn” patterns are associated with hamartomas. Unfortunately, eccentric foci of calcium or small flecks of calcium may be found in malignant lesions.
4. Nodules can be studied using a CT scanner by measuring their change in relative radiodensity after injection of contrast. This information improves the accuracy of predicting the presence of malignancy.

KEY POINTS: SOLITARY PULMONARY NODULE

1. A solitary pulmonary nodule or “coin lesion” is < 3 cm and is discrete on chest radiograph.
2. The most common causes of a pulmonary nodule are either neoplastic or infectious.
3. If the lesion proves to be cancer, anatomic lobectomy is the procedure of choice.

7. What social or clinical findings suggest that a nodule is malignant rather than benign?

Show answer
Unfortunately, none of the findings is sufficiently sensitive or specific to influence the work-up. Both increasing age and a long smoking history predispose patients to lung cancer. Winston Churchill should have had lung cancer, but he did not. Thus, the fact that the patient is the president of the spelunking club (histoplasmosis), has a sister who raises pigeons (cryptococcosis), grew up in the Ohio River Valley (histoplasmosis), works as sexton for a dog cemetery (blastomycosis), or just took a hiking trip through the San Joaquin Valley (coccidioidomycosis) is interesting associated history but does not affect the work-up of a solitary pulmonary nodule.

8. What is the most valuable bit of historic data?

Show answer
The most valuable is an old chest radiograph. If the nodule is new, it is more likely to be malignant, whereas if the nodule has not changed in the past 2 years, it is less likely to be malignant. Unfortunately, even this observation is not absolute.

9. If a patient presents with a treated prior malignancy and a new solitary pulmonary nodule, is it safe to assume that the new nodule represents metastatic disease?

Show answer
No. Even in patients with known prior malignancies, < 50% of new pulmonary nodules are metastatic. Thus, the work-up should proceed exactly as for any other patient with a new solitary pulmonary nodule.

10. How should a solitary pulmonary nodule be evaluated?

Show answer
A complete travel and occupational history is interesting but does not affect the evaluation. Because of the peripheral location of most nodules, bronchoscopy has a diagnostic yield of < 50%. Even in the best hands, sputum cytology has a low yield. CT scanning is recommended because it can identify other potentially metastatic nodules and delineate the status of mediastinal lymph nodes. As indicated previously, percutaneous needle biopsy has a diagnostic yield of approximately 80% but rarely alters the subsequent management. PET scanning may suggest cancer with accuracy.
The mainstay of management in patients who can tolerate surgery is resection of the nodule, usually by lobectomy if cancer is suspected, for diagnosis by either a minimally invasive thoracoscopy approach or a limited thoracotomy.

11. If the lesion proves to be cancer, what is the appropriate surgical therapy?

Show answer
Although several series have suggested that wedge excision of the nodule is sufficient, an anatomic lobectomy remains the procedure of choice. This can often be accomplished by a video-assisted approach. A solitary nodule that turns out to be cancer should be early-stage disease and has a 65% 5-year survival rate if there are no notable metastases. Unfortunately, the recurrence rate even for stage I tumors or a small nodule is 30% over 5 years. Recurrences are split between local and distant.

References
WEB SITE
http://www.acssurgery.com
BIBLIOGRAPHY
1. Dewey TM, Mack MJ: Lung cancer: Surgical approaches and incisions. Chest Surg Clin North Am 10:803-820, 2000.
2. Ginsberg RJ, Rubinstein LV: Randomized trial of lobectomy versus limited resection for T1 N0 non-small cell lung cancer. Lung Cancer Study Group. Ann Thorac Surg 60:615-622, 1995. Medline Similar articles Full article
3. Khouri NF, Meziane MA, Zerhouni EA, et al: The solitary pulmonary nodule: Assessment, diagnosis and management. Chest 91:128-133, 1987. Medline Similar articles
4. Miller DL, Rowland CM, Deschamps C, et al: Surgical treatment of non-small cell lung cancer 1 cm or less in diameter. Ann Thorac Surg 73:1541-1545, 2002.
5. Nesbitt J, Putnam JB Jr, Walsh GL, et al: Survival in early stage non-small cell lung cancer. Ann Thorac Surg 60:466-472, 1995. Medline Similar articles Full article
6. Walsh GL, Pisters KM, Stevens C: Treatment of stage I lung cancer. Chest Surg Clin North Am 10:17-38, 2001.

1. How common is lung cancer?

Show answer
The incidence of lung cancer is approximately 180,000 new cases annually or 54.2 per 100,000 patients. More than 162,000 patients die annually, so the overall survival rate is 10%. This number has not improved over the past 35 years despite some treatment advances because of:

1. Teenage smoking and smoking in general
2. Increased incidence in nonsmokers
3. Presentation of lung cancer in advanced stage in most patients

2. What risk factors are thought to be important in the development of lung cancer?

Show answer

* 90% of patients have a smoking history
* Chemicals (aromatic hydrocarbons, vinyl chloride)
* Radiation (radon gas and uranium)
* Asbestos
* Metals (chromium, nickel, lead, and arsenic)
* Environmental factors (air pollution, coal tar, petroleum products)

3. Do genes and heredity play a role in lung cancer?

Show answer
Yes. A family history of lung cancer probably increases the risk of getting lung cancer. Furthermore, a large array of important biomarkers that influence prognosis have been identified in lung cancer cells and lung cancer tissue.

* Past:Light microscopic evidence of vascular invasion
* Lymphatic invasion
* Cellular pleomorphism and mitotic figures

* Present:Proto-oncogenes, growth factors, growth factor receptors
o Insulin-like growth factor (IGF)
o Epidermal growth factor receptor (EGFR)
o K-ras mutation (cell growth regulation)
o C-myc overexpression (cell growth)
o bcl-2 underexpression (loss of apoptosis regulation)
* Loss of tumor suppressor genes
o p53
o Retinoblastoma (RB gene)
o Chromosomal allele loss
o Fragile histidine triad gene (FHit)
o Retinoic acid receptor α (RARα)
* Overactivation of angiogenesis
o Platelet-derived growth factor (PDGF)
o Vascular endothelial-derived growth factor (VEGF)

* Future:Gene therapy directed at above
* Antiangiogensis therapy
* Immunopotentiation
o Adoptive immunotherapy: isolation, expansion, and reinfusion of tumor-infiltrating
o lymphocytes
o Nonspecific immunostimulation
o Tumor vaccines

No single marker yet has a clear meaning with respect to prognosis in a given patient.

4. What are the major histologic types of lung cancer?

Show answer
The most important distinction is between small cell and non-small cell carcinoma because of fundamental differences in tumor biology and clinical behavior (Table 79-1). Patients with small cell lung cancer are classified as having either limited or extensive disease. Limited means that all known disease is confined to one hemithorax and regional lymph nodes, including mediastinal, contralateral hilar, and ipsilateral supraclavicular nodes. Extensive describes disease beyond these limits, including brain, bone marrow, and intra-abdominal metastases.
With small cell or neuroendocrine carcinoma, the small cell type is usually extensive at presentation, and 5-year survival is 5%. Neuroendocrine carcinoma, which is well differentiated, is known as atypical carcinoid and has a good prognosis but is not “benign.”
Table 79-1. MAJOR HISTOLOGIC TYPES OF LUNG CANCER

5. Is lung cancer screening effective?

Show answer
Old dogma: No.
Current thinking: Yes. The thinking is as follows: lung cancer accounts for more cancer deaths than other cancers. Eighty-five percent of patients present with advanced uncurable lung cancer. We have not changed survival for lung cancer. Early-stage cancers that are asymptomatic can be found by chest radiograph and helical computed tomography (CT). Unfortunately, public health policy does not endorse screening for lung cancer.

6. How do patients with lung cancer present?

7. What is a paraneoplastic syndrome?

Show answer
Paraneoplastic syndromes of lung cancer may be metabolic (e.g., hypercalcemia, Cushing’s syndrome), neurologic (e.g., peripheral neuropathy; polymyositis; or Lambert-Eaton syndrome, which is similar to myasthenia gravis), skeletal (e.g., clubbing, hypertrophic osteoarthropathy), hematologic (e.g., anemia, thrombocytosis, disseminated intravascular coagulation), or cutaneous (e.g., hyperkeratosis, acanthosis nigricans, dermatomyositis). Of interest, the presence of a paraneoplastic syndrome does not influence the ultimate curability of the lung cancer.

8. Does the staging system for lung cancer have prognostic and therapeutic importance?

Show answer
Yes. The patient’s survival is related to the stage at presentation (Table 79-2).
Table 79-2. STAGING OF LUNG CANCER

9. Describe the work-up of a patient with a mass on chest radiograph.

Show answer

The work-up should be directed toward diagnosis, staging, and risk assessment.

1. Diagnosis
* Sputum cytology-low diagnostic yield
* Brochoscopy-low diagnostic yield if tumor not visible
* CT-guided fine-needle aspiration
* Thoracoscopy and biopsy; wedge excision
2. Staging
* CT scan (chest)-tumor, mediastinal lymph node assessment
* Positron emission tomography (PET)-90% sensitive and 80% specific for nodes, mets
* Bronchoscopy-endobronchial invasion
* Thoracoscopy-lymph node sampling
* Mediastinoscopy-sample N2 and N3 nodes
3. Risk assessment
* Pulmonary
o Spirometry-V/Q screening; if borderline, must leave patient with ≥ of 800 mL FEV1 after resection
o Arterial blood gas analysis
* Cardiac
o Electrocardiogram
o History of myocardial infarction, prior intervention
* Cardiopulmonary
o Able to walk a flight of stairs; if yes, will tolerate lobectomy
o Maximal oxygen (O2) consumption < 15 mL/kg/min

10. How are patients with lung cancer treated?

Show answer
The most effective treatment for lung cancer is surgical resection. Unfortunately, 75% of patients present with advanced disease and are not candidates for resection. Fortunately, preoperative chemotherapy with a cisplatinum-containing regimen has increased the number of stage III patients who are candidates for resection. This recent innovative therapy may translate into improved survival rates. For stage III lung cancer, several clinical trials have shown an advantage to preoperative chemotherapy and radiation treatment called neoadjuvant therapy. Even lower-stage disease or tumors at high risk of recurrence may benefit from newer chemotherapeutic regimens.
KEY POINTS: LUNG CANCER

1. The overall survival rate for patients with lung cancer is 10%.
2. Ninety percent of patients have a smoking history.
3. The most effective treatment for lung cancer is surgical resection.

11. Does radiation therapy have a place in the therapy of lung cancer?

Show answer
Radiation therapy is effective palliative but not curative therapy for lung cancer. Specifically, patients who present with a superior vena cava syndrome or a blocked bronchus with distal pneumonia frequently can be “opened up” with radiation therapy. Radiation is also excellent for the palliation of pathologic bone pain. Some-but not all-clinical trials have shown some benefit from preoperative chemoradiation treatment in advanced-stage lung cancer.

12. What is the survival rate of patients treated for non-small cell lung cancer at 5 years?

Show answer

Note that for chest wall invasion with no lymph nodes, survival is 50% at 5 years, although this is still called stage IIb. Also, if stage Ia (small tumor, no positive nodes) cancer is not resected, survival decreases from 70% to 7%.

13. What is mediastinoscopy?

Show answer
Mediastinoscopy is a staging procedure in which the paratracheal, subcarinal, and proximal peribronchial lymph nodes are sampled from a small incision made in the suprasternal notch.

14. What are the indications for mediastinoscopy?

Show answer
Mediastinal staging is indicated in patients with either apparent or documented lung cancer who have:

* Known lung cancer with mediastinal lymph nodes > 1 cm accessible by cervical mediastinal exploration, as assessed by CT scan
* Adenocarcinoma of the lung and multiple mediastinal lymph nodes < 1 cm
* Central or large (> 5 cm) lung cancers with mediastinal lymph nodes < 1 cm
* Lung cancer and are at high risk of thoracotomy and lung resection

If the mediastinoscopy has negative results, the surgeon should proceed with thoracotomy, biopsy, and curative lung resection.

15. Is malignant pleural effusion or recurrent nerve involvement with tumor an absolute contraindication to surgical resection for lung cancer?

Show answer
A malignant pleural effusion is an absolute contraindication to surgical resective therapy. Conversely, both King George V and Arthur Godfrey had successful surgical resections in the face of recurrent nerve involvement with tumor.

References
WEB SITE

http://www.acssurgery.com

BIBLIOGRAPHY
1. Ginsberg RJ, Ruckdeschel JC (eds): Lung Cancer: Past, Present, and Future. Part I. Chest Surgery Clinics of North America, vol. 10. Philadelphia, W.B. Saunders, 2000.
2. Mountain EF: Revision in the international system for staging lung cancer. Chest 111:1710, 1997.
3. Pass HI: Adjunctive and alternate treatment of bronchogenic lung cancer. Chest Surg Clin North Am 1:1-20, 1991.
4. Saunders CA, Dussek JE, O’Doherty MJ, Maisey MN: Evaluation of fluorine 18-fluorodeoxyglucose: Whole body positron emission tomography imaging in staging lung cancer. Ann Thorac Surg 67:790-797, 1999. Full article
5. Sonett JR, Krasna MJ, Suntharalingam M, et al: Safe pulmonary resection after chemotherapy and high-dose thoracic radiation. Ann Thorac Surg 68:316-320, 1999. Medline Similar articles Full article
6. Strauss GM: Prognostic markers in resectable non-small-cell lung cancer. Hematol Oncol Clin North Am 11:409-434, 1997. Medline Similar articles Full article

10. What is an empyema, and what causes it?

Show answer
An empyema is a purulent (infected) effusion. Fluid or blood in the pleural space can be directly innoculated (with bugs) during surgery or trauma (33%) or by contamination from contiguous sites (50%) such as bronchopulmonary infection (most common). Most empyemas are parapneumonic, and the most commonly involved organisms are Staphylococcus aureus, enteric gram-negative bacilli, and anaerobes. Many times, infections are polymicrobial. Often there is no growth of an empyema culture because of effective antibiotic therapy or inadequate culture techniques, particularly with anaerobes.

11. What are the three stages of empyema development?

Show answer
They are the exudative stage (low viscosity fluid), fibrinopurulent stage (transitional phase with heavy fibrinous deposits and turbid fluid), and organizing stage (capillary ingrowth with lung trapping by collagen). This process usually evolves over 6 weeks.

12. How is an empyema diagnosed?

Show answer
Characteristic clinical and radiographic findings are used. Computed tomography (CT) scan is very helpful in defining loculations. Thoracentesis may reveal frank pus, and Gram stain shows many white blood cells (WBCs) and organisms. Biochemical analysis varies, but it is generally an exudate with a low pH (< 7), high LDH (> 1000 IU/L), and low glucose (< 50 mg/dL).

KEY POINTS: THORACIC SURGERY FOR NON-NEOPLASTIC DISEASE

1. Surgery is indicated for complications of tuberculosis, with the most common indication in the United States being multiple drug-resistant tuberculosis with destroyed lung and persistent cavitary disease.
2. An empyema is a purulent (infected) effusion.
3. The three stages of empyema are the exudative stage (low viscosity fluid), fibrinopurulent stage (transitional phase with heavy fibrinous deposits and turbid fluid), and organizing stage (capillary ingrowth with lung trappng by collagen).

13. How should an empyema be treated?

Show answer
Antibiotic therapy directed by Gram stain and culture. If early, tube thoracostomy may be curative. Conversion to open tube drainage (empyema tube) may be necessary if persistent purulent drainage occurs. Instillation of fibrinolytic enzymes (e.g., streptokinase or TPA) may be helpful. An infected loculated (lots of discontinuous cystic pockets) effusion <14 days old should undergo video-assisted thoracoscopic surgery (VATS) decortication (i.e., resection of the thickened, adherent peel). The probability of conversion to open thoracotomy increases with the age of the effusion or empyema.

14. What is a decortication?

Show answer
The cortex is the outside wall or peel of the empyema (like an orange). Thus, decortication is the surgical release and removal of the abscess cavity walls. Successful decortication allows the lung to expand and fill the entire pleural space; if complete expansion does not occur, then the effusion may recur, and continued lung trapping is likely.

15. What are the complications of an empyema left untreated?

Show answer
The most common is pulmonary fibrosis with lung trapping and resultant dyspnea. Others include contraction and deformity of the chest wall, spontaneous drainage through the chest wall (empyema necessitans), bronchopleural fistula, osteomyelitis, pericarditis, mediastinal or subphrenic abscess, sepsis, and death. None of these outcomes is particularly appealing, so in the absence of overwhelming contraindications, all empyemas warrant therapy.

References
WEB SITE
http://www.acssurgery.com
BIBLIOGRAPHY
1. American Thoracic Society: Diagnosis and treatment of disease caused by nontuberculous mycobacteria. Am J Respir Crit Care Med 156(suppl 2 pt 2):S1-S25, 1997.
2. Colice GL, Curtis A, Deslauriers J, et al: Medical and surgical treatment of parapneumonic effusions: An evidence-based guideline. Chest 118:1158-1171, 2000. Medline Similar articles Full article
3. de Hoyos A, Sundaresan S: Thoracic empyema. Surg Clin North Am 82:643-671, 2002. Medline Similar articles

4. Mault JR, Pomerantz M: Mycobacterium tuberculosis and other mycobacteria. Chest Surg Clin North Am 9:227-238, 1999.
5. Pomerantz M, Brown J: Surgery of pulmonary mycobacterial disease. In Kaiser LR, Kron IL, Spray TL (eds): Mastery of Cardiothoracic Surgery. Philadelphia, Lippincott-Raven, 1998, pp 265-271.
6. Wiedeman HP, Rice TW: Lung abscess and empyema. Semin Thorac Cardiovasc Surg 7:119-128, 1995.

6. What is a pleural effusion?

Show answer

Pleural fluid is generated in normal adults at a rate of 5-10 L per 24 hours in the combined hemithoraces, but normal adults have only 20 mL of pleural fluid present at any time. Pleural effusions develop when there is either increased production or decreased resorption. Pathologic conditions leading to effusions include increased capillary permeability (inflammation, tumor), increased hydrostatic pressure (e.g., in congestive heart failure [CHF]), decreased lymphatic drainage (tumor, radiation fibrosis), decreased oncotic pressure (hypoalbuminemia), or combinations of these.

7. How does one determine the cause of a pleural effusion?

Show answer
History and physical examination, chest radiograph (upright and decubitus), and thoracentesis are used. Thoracentesis should be used to evaluate the pleural fluid. Bloody fluid is typical of trauma, pulmonary embolism, malignancy, milky fluid with chylothorax (triglyceride > 110), and purulent fluid with empyema. Fluid should be checked for cell count; cytology; pH; Gram stain; culture; and glucose, protein, lactate dehydrogenase (LDH), amylase, and triglyceride level. Exudates have a protein ratio > 0.5 and an LDH ratio > 0.6. The most common cause of transudate is CHF; the most common cause of exudate is malignancy and infection. Glucose < 60 mg/dL is seen in only parapneumonic effusions, rheumatoid effusion, tuberculous pleuritis, and malignancy.

8. What is the management of a pleural effusion?

Show answer
Thoracentesis or a tube thoracostomy should be used to evacuate the effusion completely. The underlying problem (e.g., CHF) should be corrected if possible. If the effusion is persistent (e.g., malignancy), then pleurodesis (stick the parietal and visceral pleurae together) can be performed with sclerosants (talc) or mechanical abrasion. Pleural symphysis (stuck pleura) results in decreased surface area for production, eliminates the pleural space for accumulation, and prevents lung collapse and compression. Chest tubes are generally removed when output is < 75 mL per 24 hours.

9. What does an air-fluid level on an initial chest radiograph indicate?

Show answer
An air-fluid level before any drainage procedure may represent a bronchopleural fistula. These fistulas may resolve with chest tube drainage or require open thoracotomy for definitive repair.

1. What are the clinical manifestations of pulmonary tuberculosis?

Show answer
They can be almost anything or nothing (it has been stated that if you know tuberculosis, you know all of medicine), but the most common symptoms and signs are chronic fever; weight loss; night sweats; and cough, sometimes with hemoptysis. Chest radiograph typically shows upper lobe infiltrates, with or without cavitation, and can be misdiagnosed as a neoplastic process. HIV-positive or immunocompromised patients usually have mediastinal adenopathy, pleural effusions, and a miliary pattern.

2. How is the diagnosis of pulmonary tuberculosis made?

Show answer
Positive acid-fast bacilli (AFB; “red snappers”) smear in sputum sample; sensitivity improves with bronchoalveolar lavage (BAL) specimens. Culture growth will identify specific organism (i.e., atypicals) as well as drug sensitivity (watch out for multidrug resistance [MDR]).

3. What is the current medical treatment for active tuberculosis?

Show answer
Initial therapy consists of a 6-month regimen with isoniazid, rifampin, and pyrazinamide for the first 2 months, and then isoniazid and rifampin for another 4 months. With this schedule, 95% of patients have tuberculosis-negative sputum at the end of therapy. Partial responders should receive therapy for longer than 6 months, and those with MDR-TB may receive ethambutol or streptomycin.

4. What are the indications for surgery in patients with tuberculosis?

Show answer
Surgery is indicated for complications of the disease. The most common surgical indication in the United States is MDR-TB with destroyed lung and persistent cavitary disease. This lung tissue is resistant to drug penetration and can also “spill” organsims into healthy lung tissue. Other indications include hemoptysis, exclusion of lung cancer, bronchial stenosis, bronchopleural fistula, middle lobe syndrome, or mycobacterium other than tubercle bacilli (MOTT).

5. What is MOTT, and what is the role of surgery with this disease?

Show answer
Atypical mycobacterial infections, nontuberculosis mycobacterial infections, and infection with mycobacteria other than tuberculosis are synonyms. The most common of these organisms is the Mycobacterium avium complex (MAC). Others include M. chelonae and abscesses, M. kansaii, M. fortuitum, and M. xenopi. MAC typically produces fibrocavitary disease of the upper lobes or the middle lobe or lingula of thin, white women. Surgery is indicated for localized disease, and in combination with drug therapy, it results in sputum conversion in ≥ 95% of patients with relapse rates of < 5%. Other indications for surgery are the same as for regular tuberculosis.

27. Should the Ross procedure ever be performed?

Show answer
For: The Ross procedure provides excellent, long-term (sometimes lifelong) hemodynamic relief of aortic stenosis and avoids the need for mechanical valves, thus avoiding the need for anticoagulation. An additional benefit is the regenerative capacity of the aortic autograft; it may actually increase in size as the patient grows.
Against: The Ross procedure is a technically demanding operation and has a significant learning curve with high associated morbidity. The procedure destroys a normal pulmonary valve, thus potentially giving the patient two (instead of one) valve diseases.

28. Should a tissue valve be used in young adults between ages 15 and 30 years?

Show answer
For: Anticoagulation is not necessary for tissue valves placed in the aortic position; thus, the risk of significant bleeding complications in active patients is avoided. For women in the childbearing years, the advantages are very real.
Against: Early valve dysfunction secondary to valve calcification occurs more aggressively in younger patients; thus, valve replacement may be necessary before 10 years.

29. Should minimally invasive approaches to aortic valve replacement be attempted?

Show answer
For: Aortic valve replacement can be performed via a ministernotomy. This approach avoids a complete sternotomy and may improve cosmesis and decrease blood loss.
Against: Aortic valve replacement via conventional sternotomy is surprisingly well tolerated and has excellent long-term results. Comparative studies have identified no difference in quality of life between minimally invasive and conventional aortic valve replacement. Furthermore, long-term results of the minimally invasive approach are not yet available.

References
WEB SITE
http://www.acssurgery.com
BIBLIOGRAPHY
1. Akins CW, Hilgenberg AD, Vlahakes GJ, et al: Results of bioprosthetic versus mechanical aortic valve replacement performed with concomitant coronary artery bypass grafting. Ann Thorac Surg 74:1098-1106, 2002. Medline Similar articles Full article
2. Al-Halees Z, Pieters F, Qadoura F, et al: The Ross procedure is the procedure of choice for congenital aortic valve disease. J Thorac Cardiovasc Surg 123:437-441, 2002. Medline Similar articles Full article
3. Bonow RO, Carabello B, de Leon AC, et al: ACC/AHA guidelines for the management of patients with valvular heart disease. Executive summary. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Patients With Valvular Heart Disease). J Heart Valve Dis 7:672-707, 1998. Medline Similar articles
4. Borer JS: Aortic valve replacement for the asymptomatic patient with aortic regurgitation: A new piece of the strategic puzzle. Circulation 106:2637-2639, 2002. Medline Similar articles Full article
5. Carabello BA: Evaluation and management of patients with aortic stenosis. Circulation 105:1746-1750, 2002.
6. Chaliki HP, Mohty D, Avierinos JF, et al: Outcomes after aortic valve replacement in patients with severe aortic regurgitation and markedly reduced left ventricular function. Circulation 106:2687-2693, 2002. Medline Similar articles
7. Cribier A, Eltchaninoff H, Bash A, et al: Percutaneous transcatheter implantation of an aortic valve prosthesis for calcific aortic stenosis: First human case description. Circulation 106:3006-3008, 2002. Medline Similar articles Full article
8. Detter C, Deuse T, Boehm DH, et al: Midterm results and quality of life after minimally invasive versus conventional aortic valve replacement. Thorac Cardiovasc Surg 50:337-341, 2002. Similar articles Full article
9. Detter C, Fischlein T, Feldmeier C, et al: Aortic valvotomy for congenital valvular aortic stenosis: A 37-year experience. Ann Thorac Surg 71:1564-1571, 2001. Full article
10. Lamb HJ, Beyerbacht HP, de Roos A, et al: Left ventricular remodeling early after aortic valve replacement: Differential effects on diastolic function in aortic valve stenosis and aortic regurgitation. J Am Coll Cardiol 40:2182-2188, 2002. Medline
11. McCrindle BW, Blackstone EH, Williams WG, et al: Are outcomes of surgical versus transcatheter balloon valvotomy equivalent in neonatal critical aortic stenosis? Circulation 104(suppl I):I152-II58, 2001. Full article
12. Paparella D, David TE, Armstrong S, Ivanov J: Mid-term results of the Ross procedure. J Card Surg 16:338-343, 2001. Medline Similar articles
13. Russo CF, Mazzetti S, Garatti A, et al: Aortic complications after bicuspid aortic valve replacement: long-term results. Ann Thorac Surg 74:S1773-S1776, 2002.
14. Yener N, Oktar GL, Erer D, et al: Bicuspid aortic valve. Ann Thorac Cardiovasc Surg 8:264-267, 2002. Medline Similar articles

1. What are the most common causes of aortic stenosis?

Show answer
Rheumatic heart disease is now a rare cause of aortic stenosis, so the most common causes are now congenital anomalies and calcific (degenerative) disease.

2. What is the most common anatomic anomaly in aortic stenosis?

Show answer
Bicuspid aortic valve (normal valve is tricuspid) occurs in 2% of the general population. More than 50% of patients with aortic stenosis older than age 15 years have a bicuspid aortic valve.

3. What are the most common symptoms of aortic stenosis in adults? Infants?

Show answer
Most patients with aortic stenosis are asymptomatic. In adults, the development of angina, syncope, or dyspnea on exertion (congestive heart failure [CHF]) portends a poor prognosis unless valve replacement is performed. CHF is the most common presentation of aortic stenosis in infants.

4. What is the expected survival of patients with aortic stenosis?

Show answer
Asymptomatic patients with aortic stenosis have a near normal life expectancy. After symptoms occur, the 3-year mortality of patients who do not undergo valve surgery is 75%. Thus, it is important to catch patients before they are symptomatic.

5. What is the most feared complication of aortic stenosis?

Show answer
Sudden death.

6. What physical findings suggest aortic stenosis?

Show answer
Systolic crescendo-decrescendo (diamond-shaped) murmur, diminished peripheral pulses, or delayed pulse upstroke (call it pulsus parvus et tardus if you want to shine on medicine rounds).

7. What are the typical findings of aortic stenosis on chest radiographs and electrocardiogram (ECG)?

Show answer
Both chest radiographs and ECG may show normal results even with severe aortic stenosis; thus, these are not good screening tests. On chest radiograph, calcification of the aortic valve and an enlarged cardiac silhouette may be seen. ECG is fairly sensitive in detecting left ventricular hypertrophy (LVH) and may also reveal conduction defects (these occur secondary to extension of valvular calcification into the adjacent conduction tissue).

8. How is the diagnosis of aortic stenosis confirmed?

Show answer
Echocardiography with Doppler ultrasound is nearly 100% accurate in diagnosing hemodynamically significant aortic stenosis. This noninvasive test also accurately estimates aortic valve area and gradient and has all but replaced cardiac catheterization as the diagnostic test of choice for aortic stenosis.

9. When is cardiac catheterization indicated in patients with echocardiography-confirmed aortic stenosis?

Show answer
Approximately 50% of patients with aortic stenosis will have some degree of associated coronary artery disease (CAD). Patients requiring aortic valve replacement who have surgically treatable CAD should have coronary artery bypass graft (CABG) performed at the time of the valve surgery. Thus, coronary angiography should precede aortic valve surgery in patients ≥ 40 years or in those with angina or significant risk factors for CAD.

10. When is an operation indicated for aortic stenosis?

Show answer
Asymptomatic patients with aortic stenosis rarely require surgery; however, essentially all patients with symptomatic aortic stenosis should undergo aortic valve replacement. Indications for valve replacement in asymptomatic patients include progressive LVH, left ventricular dysfunction, or valve area < 0.6 cm2.

11. Can aortic valvotomy be used to treat aortic stenosis?

Show answer
Although valvotomy effectively palliates patients with congenital aortic stenosis, it is rarely curative. Most children with the condition will require aortic valve replacement later in life. Aortic valve replacement, not valvotomy, is the procedure of choice in adults.

12. What is the Ross procedure?

Show answer
The patient’s own pulmonary valve and proximal pulmonary artery are harvested (autograft) and used to replace the native, diseased aortic valve. A pulmonary allograft (harvested and frozen from a human cadaver) is then used to reconstruct the right ventricular outflow tract.

13. What type of valvular prosthesis should be used in children requiring aortic valve replacement?

Show answer
In children younger than 15 years (as well as young adults between the ages of 15 and 30 years), rapid calcification occurs in porcine valves placed in the aortic position. Thus, mechanical valves (or the Ross procedure; see question 12) should be used.

14. What type of valvular prosthesis should be used in adults requiring aortic valve replacement?

Show answer
Whether to use a mechanical or a bioprosthetic valve depends upon the patient’s age and the risk of lifelong anticoagulation. Mechanical aortic valves afford excellent long-term relief of hemodynamically significant aortic stenosis but require lifelong anticoagulation. Bioprosthetic valves in the aortic position do not require anticoagulation; however, 30% of these valves exhibit structural deterioration at 10 years.

15. What are the most common causes of aortic insufficiency?

Show answer
Infective valvular endocarditis, aortic dissection, connective tissue disease (e.g., Marfan syndrome), and prosthetic (mechanical) valve dysfunction.

16. What physical findings suggest aortic insufficiency?

Show answer
A rapid rise and fall of the arterial pulse (refer to this as a water-hammer pulse or, better yet, a Corrigan’s pulse to dazzle your chief medicine resident).

17. What is a Quincke’s pulse?

Show answer
Capillary pulsations secondary to aortic insufficiency that can be detected by transmitting a light through the patient’s fingertip or by pressing a glass slide on his or her lip.

18. How is the diagnosis of aortic insufficiency confirmed?

Show answer
As with aortic stenosis, echocardiography or Doppler ultrasound are the tests of choice.
KEY POINTS: AORTIC VALVULAR DISEASE

1. The most common causes are congenital anomalies and calcific (degenerative) disease.
2. The most feared complication is sudden death.
3. Surgical intervention is indicated for all patients with symptoms and for asymptomatic patients with left ventricular hypertrophy, left ventricular dysfunction, or valve area < 0.6 cm2.

19. When is an operation indicated for aortic insufficiency?

Show answer
This depends on the cause of the aortic insufficiency and whether it is acute or chronic. Aortic insufficiency caused by an ascending aortic dissection is a surgical emergency. Aortic insufficiency secondary to infective endocarditis may or may not require aortic valve replacement (see question 20). Patients with chronic (mild to moderate) aortic insufficiency that does not progress enjoy a near-normal life expectancy. Patients with severe aortic insufficiency require valve surgery before they develop irreversible left ventricular dysfunction. Asymptomatic patients with severe aortic insufficiency benefit from aortic valve replacement when their left ventricle begins to fail or enlarges (end-systolic left ventricular diameter ≥ 55 mm or end-diastolic left ventricular diameter ≥ 75 mm).

20. What are the indications for aortic valve replacement in patients with infective endocarditis?

Show answer
Progressive CHF, recurrent septic emboli, infection uncontrolled by antibiotics (often fungal, gram-negative rods or Staphylococcus aureus) and a prolongation of the P-R interval. Although hard to believe, the junction of the left and noncoronary aortic valvular cusps is immediately adjacent to the atrioventricular (A-V) node. Thus, a perivalvular abscess can slow A-V conduction.

21. What is the operative mortality of aortic valve replacement?

Show answer
Thirty-day mortality is ≤ 4%. In low-risk patients, the mortality can approach 1%; however, the mortality skyrockets to 20% in patients with associated CAD and left ventricular dysfunction.

22. What are the complications of aortic valve replacement?

Show answer

* Bleeding requiring reexploration (2%)
* Heart block (2%), again, caused by the proximity to the A-V node
* Stroke (1%) caused by air or calcium left in the heart after closure of the aortotomy
* Low cardiac output (≥ 5%) in patients with preoperative left ventricular failure

23. What are the long-term results of aortic valve replacement?

Show answer
Patients who survive the immediate perioperative period improve both symptomatically and functionally, and age-corrected survival returns to near normal (75% at 10 years). Aortic valve replacement partially reverses LVH and dilatation.

24. Can balloon valvotomy be used for adult calcific aortic stenosis?

Show answer
Initially, it was hoped that balloon valvotomy could replace surgery and provide long-term palliation in older patients who are at higher surgical risk because of decreased ventricular function. However, it is exactly this group who fare least well after balloon valvotomy; < 50% are alive at 1 year after surgery.

25. What are the indications for balloon valvotomy?

Show answer
Balloon valvotomy is effective in infants and young children with congenital aortic stenosis and a tiny aortic annulus. The intermediate results are similar to surgical valvotomy. In adults, balloon valvotomy should be used primarily as a bridge to aortic valve replacement or transplantation in critically ill patients. Temporary improvement in ventricular function suggests that the patient will benefit from aortic valve replacement. Balloon valvotomy may also relieve the symptoms of women with severe aortic stenosis in the second trimester of pregnancy.

26. Is percutaneous aortic valve replacement feasible?

Show answer
Although percutaneous transcatheter placement of a bioprosthetic aortic valve has been reported, this approach is still largely experimental.

16. What is systolic anterior motion (SAM) of the mitral valve?

Show answer
SAM is a complication of mitral valve repair. After mitral valve repair, the anterior leaflet of the mitral valve may billow into the left ventricular outflow tract during systole, creating two problems: (1) dynamic left ventricular outflow tract obstruction and (2) mitral regurgitation (anterior displacement of the anterior leaflet causes it to be foreshortened). SAM should be suspected if cardiac output is low after mitral valve repair and may be diagnosed by echocardiography. It is exacerbated by an increased contractile state of the myocardium, so inotropic agents should be avoided. Patients with SAM are treated by volume-loading and beta-blocking agents. If these measures fail, the valve should be replaced.

References
WEB SITE
http://www.acssurgery.com
BIBLIOGRAPHY
1. Bonow RO, Carabello B, de Leon AC Jr, et al: ACC/AHA guidelines for the management of patients with valvular heart disease. J Am Coll Cardiol 32:1486-1588, 1998. Full article
2. Carabello BA: The ten most commonly asked questions about mitral regurgitation. Cardiol Rev 10:321-322, 2002. Medline Similar articles Full article
3. Enruquez-Sarano M, Nkomo V, Mohty D, et al: Mitral regurgitation: Natural history in operated and nonoperated patients. Adv Cardiol 39:122-129, 2002.
4. Galloway AC, Grossi EA, Bizekis CS, et al: Evolving techniques for mitral valve reconstruction. Ann Thorac Surg 236:288-293, 2002. Full article
5. Irvine T, Li XK, Sahn DJ, Kenny A: Assessment of mitral regurgitation. Heart 88(suppl 4):iv11-19, 2002.