Cardiothoracic Surgery

         ASPIRATION PNEUMONIA :

standing/sitting upright - superior segment of the R lower lobe

 laying down -posterior segment of the right lower lobe

Only way to aspirate into the upper lobes is to aspirate the foreign body while lying down on their side

·         Developed in 1977, the Goldman scale quantifies operative risk for MI based on several variables assessed by history, physical examination, and simple laboratory data.

·         Cardiac Risk Index:

History of:

1.       Ischemic heart disease

2.       Cerebrovascular disease: any H/O TIA or CVA.

3.       Diabetes mellitus: use of insulin

4.       Renal insufficiency: creatinine >2.0 mg/dL

5.       High-risk surgery: intrathoracic, intraabdominal, or suprapubic vascular

One point is assigned for each positive; scores >2 are higher-risk and warrant use of beta blockade.

·         Off-pump CABG (OPCAB):

CABG can be performed without cardiopulmonary bypass and arrest of the heart. When done with the heart beating through a median sternotomy, CABG is then called an OPCAB. The heart is positioned with commercially available stabilization devices, and the vessel to be bypassed is immobilized and snared to provide temporary occlusion. The venous or arterial conduit is then sewn to the immobilized coronary artery, and the occlusion of the vessel is released.

Patients with comorbidities of lung disease, cerebrovascular disease, renal disease, or severe peripheral vascular disease may have improved outcomes when CABG is performed without the use of cardiopulmonary bypass.

·         Implantation of an automated implantable cardiac defibrillator (AICD) is indicated for patients with life-threatening ventricular tachyarrhythmias.

·         Trans Myocardial Revascularization (TMR) uses a laser to burn small holes from the endocardium to the epicardium. Although it was originally believed that the laser brought blood from the endocardial capillary network to the myocardium, it has been repeatedly observed that laser-created channels are filled with thrombus within 24 hours and subsequently occluded. Therefore, it is postulated that the laser energy invokes an inflammatory response with a resultant increase in angiogenic factors (vascular endothelial growth factor, tumor growth factor beta, fibroblast growth factor).

·         Gorlin Formula: A formula used to calculate the area of a heart valve

Mitral Valve Area= C.O. /

·         SAM (systolic anterior motion) 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.

·         Ross procedure:

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.

·         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).

·         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.

·         The closing volume is conceptually the remaining lung volume at the end of expiration below which alveolar collapse begins to occur, causing intrapulmonary right-to-left shunting and thus desaturation of blood in the left atrium. In a normal young person this closing volume is well below the functional residual capacity (FRC); thus, such physiologic shunting does not occur until there is a decrease in the elastic properties of the lung. Although FRC gradually increases with age, so does the effective closing volume. Eventually some alveoli are being underventilated (at end-expiration), allowing physiologic right-to-left shunting to occur. Closing volume is unchanged, but FRC decreases during surgery (i.e., shunting occurs). Closing volume has no direct relationship to the oxygen content of the mixed venous blood.

·         Higher levels of PEEP can be associated with decreases in cardiac output as a consequence of an effective decrease in the preload to the left ventricle owing to impaired left ventricular filling.

·         Eighty-five per cent of bronchial adenomas are carcinoid tumors. Typical carcinoid tumors have few mitotic figures and infrequent lymph node metastases (fewer than 10%). Only 10% to 15% of patients present with the carcinoid syndrome (flushing, wheezing, diarrhea). Survival after resection is more than 90% at 5 years but decreases to approximately 50% for atypical histology.

·         Adenoid cystic carcinomas (cylindromas) are commonly observed salivary gland tumors that can occur in the conducting airways. The undifferentiated solid type is associated with distant metastases, of which the cribriform and tubular types are associated with perineural and submucosal invasion. Most patients (60%) can be resected for cure.

·         In the early postoperative period after repair of obstructed forms of TAPVC, acute episodes of pulmonary hypertension may develop as a response to stress. To minimize this potentially fatal complication, infants are kept anesthetized with fentanyl and pancuronium for at least 48 hours.

·         Management of newborn infants with tricuspid atresia: bidirectional superior cavopulmonary (Glenn) anastomosis or a Fontan procedure.

·         Fibrosing mediastinitis as a complication of histoplasmosis or ingestion of methysergide.

·         Perforation of the esophagus in the chest is a surgical catastrophe that requires aggressive intervention in virtually all circumstances. While that intervention can usually consist of efforts to patch the perforation and drain the mediastinum, concomitant obstructive esophageal disease, whether inflammatory stenosis or cancer, mandates removal or bypass of the obstruction if control of the leak and its consequent persisting mediastinal and pleural contamination is to be accomplished. For distal esophageal cancers, many thoracic surgeons would use the classic Ivor-Lewis operation, which consists of mobilizing the stomach in the abdomen and then performing a right thoracotomy with mediastinal cleanout, esophagectomy, and esophagogastrostomy. In some circumstances, and by some surgeons’ preference, a left thoracotomy approach might be used.

·         Myocardial Contusion: The most helpful ECG finding is the presence of a new right bundle branch block, which occurs because of damage to the anterior portion of the interventricular septum; ST-segment and T-wave changes and even the development of new Q waves may be seen.

Radionuclide angiography is most useful because it suggests the degree of myocardial impairment caused by decreased compliance.

·         Chylothorax may occur after intrathoracic surgery, or it may follow malignant invasion or compression of the thoracic duct. Intraoperative recognition of a thoracic duct injury is managed by double ligation of the duct. Direct repair is impractical owing to the extreme friability of the thoracic duct. Injuries not recognized until several days after intrathoracic surgery frequently heal following the institution of a low-fat diet and either repeated thoracentesis or tube thoracostomy drainage. A low-fat, mediumchain triglyceride diet often reduces the flow of chyle. Failure of this treatment modality requires direct surgical ligation of the thoracic duct. This is best approached from below the diaphragm, regardless of the site of intrathoracic injury.