John Baldwin

Importance of intercostal artery reattachment during thoracoabdominal aortic aneurysm repair

PURPOSE We studied the relationship of neurologic deficit to ligation, reimplantation, and preexisting occlusion of intercostal arteries to determine which arteries and consequent management are most critical to outcome in thoracoabdominal aortic aneurysm repair. METHODS From February 1991 to July 1996, 343 patients with thoracoabdominal aortic aneurysms underwent repair by one surgeon. In this study, only Crawford types I, II, and III (n = 264) were considered. Of these, 110 (42%) were type I, 116 (44%) type II, and 38 (14%) type III. The adjuncts of distal aortic perfusion and cerebrospinal fluid drainage were used in 164 patients (62%). Data were analyzed by contingency table and by multiple logistic regression. RESULTS Early neurologic deficit occurred in 23 patients (8.7%), and late deficit in 10 patients (3.8%). Neurologic deficit in patients with at least one reimplantation and no ligation of arteries T11 or T12 occurred in 19 of 147 (12.9%). Neurologic deficit for occlusion of the same arteries occurred in 11 of 111 (9.9%), whereas for ligation of T11 and T12 neurologic deficit occurred in three of six (50%; reimplantation, p < 0.03; occlusion, p < 0.006). In addition, reimplantation of intercostal arteries T9 or T10 was significantly associated with reduced late neurologic deficit in multivariate analysis (p = 0.05). No other intercostal artery status was associated with modification of the neurologic deficit rate. Multivariate analysis showed type II aneurysms and acute dissections to be significantly associated with an increased risk of postoperative neurologic deficit (p < 0.0009, 0.002, respectively). Adjuncts were protective (p < 0.007), most often in types II and III (14.1% neurologic deficit in type II with adjunct, 35.3% without; 0% in type III with adjunct, 20% without). CONCLUSION Patients with patent arteries at the T11/T12 level have highly variable outcomes depending on whether the arteries are reattached or ligated. Our data suggest that reimplantation of thoracic intercostal arteries T11 and T12 is indicated when these arteries are patent. Reimplantation of T9 and T10 lowers the risk of late neurologic deficit, probably by decreasing the spinal cords vulnerability to changes in blood and cerebrospinal fluid pressure in the days after surgery. Adjuncts lower overall risk and provide adequate time for targeted intercostal artery reimplantation.

Cerebrospinal fluid drainage and distal aortic perfusion: Reducing neurologic complications in repair of thoracoabdominal aortic aneurysm types I and II

PURPOSE This study was conducted to evaluate the role of cerebrospinal fluid (CSF) drainage and distal aortic perfusion (DAP) in the prevention of postoperative neurologic complications for high-risk patients who had undergone type I and type II thoracoabdominal aortic aneurysm (TAAA) repair. METHODS CSF drainage and DAP were used as an adjunct in the treatment of 94 patients with TAAA (31 type I, 63 type II) between September 1992 and December 1994; 67 were men and 27 were women. The median age was 64 years (range, 28 to 88 years). Aortic dissection occurred in 35 of 94 patients (37%). Thirty-six of 94 patients (38%) had previously undergone proximal aortic surgery. All patients underwent intraoperative DAP and perioperative CSF drainage. Median aortic cross-clamp time was 67 minutes (range, 20 to 131 minutes). RESULTS The 30-day survival rate was 90% (85 of 94 patients). Early neurologic complications occurred in 5 of 94 patients (5%), and late neurologic complications occurred in 3 of 94 patients (3%). We compared the neurologic complications of our current group of 94 patients with the data from 42 patients (control group) who also underwent repair of TAAA type I and type II with only simple cross-clamp and without CSF drainage or DAP. Both groups were treated by the senior author (HJS) at the same institution. Total neurologic complications for the current group occurred in 8 of 94 patients (9%) versus 8 of 42 patients (19%) for the control group (p=0.090). Neurologic complications for patients with type II TAAA occurred in 8 of 63 patients (13%) versus 17 of 42 patients (41%) (p=0.014). For all patients with aortic clamp times >or=45 minutes, neurologic complications occurred in 7 of 55 (13%) versus 7 of 18 (39%) (p=0.033). CONCLUSION The period of risk during aortic cross-clamp time is reduced with the adjuncts of CSF drainage and DAP, which significantly lower the incidence of neurologic complications after repair of TAAA types I and II.

Holmium: YAG laser transmyocardial revascularization relieves angina and improves functional status

BACKGROUND Transmyocardial revascularization (TMR) surgery uses laser channeling of diseased myocardium to treat ischemia and angina. Rigorous prospective randomized studies have been previously unavailable. METHODS Forty-three patients were randomized to a medication group and 43 to a group scheduled for TMR surgery and medication. All had advanced cardiac ischemia with CCSA class 3 or 4 angina, took at least 2 cardiac medications at maximum doses, and were ineligible for angioplasty or bypass. RESULTS Forty-two of 43 TMR group patients received surgery and were discharged after hospitalizations averaging 3.2 days. Two suffered perioperative MIs, with one death. Four others died within 12 months of surgery, 3 from cardiac events and 1 from pneumonia. Five medical group patients died from cardiac events within 12 months. Three, 6, and 12 month exams showed angina class improvement in TMR patients compared to preoperative values (3.86 +/- 0.05 vs 1.71 +/- 0.2, P < 0.0001), and to controls at 12 months (3.77 +/- 0.07 vs 1.71 +/- 0.2, P < 0.0001). Exercise tolerance improved in TMR patients over preoperative values, and was better than medication group scores after 12 months (490 +/- 17 sec. vs 294 +/- 12 sec., p = 0.0002). CONCLUSIONS Holmium:YAG laser channeling of the myocardium improves function and reduces angina in advanced cardiac patients who lack alternative therapeutic options.

Pharmacokinetics of liposomal aerosolized cyclosporine A for pulmonary immunosuppression

BACKGROUND The results of pulmonary transplantation are compromised by acute and chronic rejection. We hypothesized that a liposomal form of aerosolized cyclosporine A (CsA) would be selectively deposited and concentrated in the lungs. The theoretical advantage of this therapy is selective pulmonary immunosuppression with prolonged utilization. METHODS Eighteen dogs were endotracheally intubated; aerosolized liposomal CsA was administered for 15 min. CsA levels were measured in whole blood, lung, trachea, heart, kidney, liver, and spleen at various times after treatment. RESULTS The lung rapidly absorbs aerosolized liposomal CsA; other organs have much lower concentrations. The retention of pulmonary CsA delivered by liposome aerosol is approximately 120 min in this model. CONCLUSIONS Aerosolized liposomal CsA is selectively deposited and concentrated in the lungs; other organs absorb less CsA.

LONG-TERM IN VIVO LEFT VENTRICULAR ASSIST DEVICE STUDY WITH A TITANIUM CENTRIFUGAL PUMP

A totally implantable centrifugal artificial heart has been developed. The plastic prototype, Gyro PI 601, passed 2 day hemodynamic tests as a functional total artificial heart, 2 week screening tests for antithrombogenicity, and 1 month system feasibility. Based on these results, a metallic prototype, Gyro PI 702, was subjected to in vivo left ventricular assist device (LVAD) studies. The pump system employed the Gyro PI 702, which has the same inner dimensions and the same characteristics as the Gyro PI 601, including an eccentric inlet port, a double pivot bearing system, and a magnet coupling system. The PI 702 is driven with the Vienna DC brushless motor actuator. For the in vivo LVAD study, the pump actuator package was implanted in the preperitoneal space in two calves, from the left ventricular apex to the descending aorta. Case 1 achieved greater than 9 month survival without any complications, at an average flow rate of 6.6 L/min with 10.2 W input power. Case 2 was killed early due to the excessive growth of the calf, which caused functional obstruction of the inlet port. There was no blood clot inside the pump. During these periods, neither case exhibited any physiologic abnormalities. The PI 702 pump gives excellent results as a long-term implantable LVAD.

Actual versus actuarial analysis for cardiac valve complications: the problem of competing risks.

Methods for analyzing rates of events such as heart valve failure following surgery are important for comparing different techniques and devices; however, in patients undergoing major surgery, other risks such as mortality compete with the risk of heart valve failure to determine each patients final outcome. When multiple, mutually exclusive endpoints are possible, a situation known to statisticians as a competing risks problem arises. No single statistical technique that is currently available provides an entirely satisfactory solution to this problem. We argue that in order for valve failure incidences to be useful clinically, the overall patient outcome milieu from which these failures arise must be considered. In this article, we review recent work in the area of competing-risks analysis as it pertains to heart valve surgery outcome.

Chest radiograph heterogeneity predicts functional improvement with volume reduction surgery

BACKGROUND Using a historical cohort study model, we tested the hypothesis that heterogeneity of emphysematous changes on the preoperative chest radiograph correlated with favorable outcome of lung volume reduction surgery. METHODS The test population consisted of 21 patients with severe emphysema who were being treated at a 1,000-bed university-affiliated tertiary teaching hospital. A simple but quantitative index of heterogeneity has been devised, whereby the preoperative posteroanterior chest radiographic lung fields are divided into four geometric quadrants. Each quadrant is scored (0 to 4) for emphysematous changes by two radiologists blinded as to subsequent patient management and outcome. Criteria for determining presence of emphysema were hyperlucency, decreased vascular markings, and parenchymal crowding indicating compressed lung. Heterogeneity index is the sum of the two highest scores minus the two lowest, with a maximum index of 8 and a minimum of 0. Preoperative chest radiographs and postoperative changes in forced expiratory volume in 1 second were examined. RESULTS The heterogeneity index was positively correlated with change in forced expiratory volume in 1 second after operation with an r2 of 0.31 and an average increase of 117 mL per unit increase in heterogeneity index (p < 0.009). CONCLUSIONS This simple index of heterogeneity may be useful as a predictor of improved pulmonary function after lung volume reduction surgery.

Physiologic characteristics of canine skeletal muscle: implications for timing skeletal muscle cardiac assist devices

BACKGROUND Optimal clinical stimulation for skeletal muscle cardiac assist systems (such as dynamic cardiomyoplasty) is not clearly defined. The pressure-generating capacity of canine skeletal muscle ventricles (SMVs) at a variety of preloads and stimulation frequencies was examined as was time for SMVs to develop peak pressure. METHODS SMVs were analyzed just after construction and after 3 months of electrical conditioning. Pressure generation and time to develop peak pressure were determined using a distensible mandrel. RESULTS Higher preloads resulted in increased pressure generation; conditioned SMVs generated significantly less pressure than unconditioned SMVs. Increasing stimulation frequency from 20 to 50 Hz increased pressure-generating capacity; increases beyond 50 Hz did not result in further increases. Time to 90% peak pressure was least at 10 HZ and 65 Hz. CONCLUSIONS Higher stimulation frequencies and preloads result in a more quickly contracting muscle, which generates more pressure. Midrange stimulation frequencies of 30 Hz provide optimal muscle strength and minimize time to develop peak pressure. Initiation of contraction should begin before the time maximal pressure is desired.

Valvular heart disease

Approach to the patient Cardiac murmurs Prevention of valvular heart disease Aortic stenosis Chronic aortic Regurgitation Acute aortic regurgitation Mitral stenosis Mitral valve prolapse Chronic mitral regurgitation Acute mitral regurgitation Pulmonic stenosis Pulmonic regurgitation Tricuspid stenosis Tricuspid regurgitation Mixed single valve disease Multiple valve disease Infective endocarditis Drug induced valvular heart disease Prosthetic heart valves Pregnancy and valvular heart disease Valvular heart disease in the elderly Quality improvement in valvular heart disease

Valvular surgery in the transplanted heart.

Cardiac transplantation has evolved, over the past 35 years, to become a well recognized and reliable modality for the treatment of end-stage heart failure. Presently, its application is limited only by the availability of suitable numbers of allografts, and this problem will likely be solved by the introduction of xenograft transplantation in the next few years. Cardiac transplantation has become so safe and reliable that, a number of years ago, it was already true that 5-year survivors of cardiac allografts had survival expectations statistically equivalent to those of the age-matched general population. Thus, it may not be surprising that many other medical problems, ranging from lung disease to kidney failure to malignancies, occur in transplant patients at intervals. Although some of these illnesses are, of course, related to the transplant and to attendant use of immunosuppression, many are of the same nature as those encountered in nontransplant patients. As lifestyle and functional survival have improved and heart transplant patients have become more like people who have not undergone transplants, so have their illnesses become similar in pathology (though not always in presentation) and treatment to those of the general population [1].