Microbiology of infection in mechanical circulatory support.

The results of MCSS therapy for patients with severe heart failure are improving, and there are increasing numbers of implants as device therapy enters the era of permanent use (i.e., destination therapy). Device-related infection of implanted pumps and sepsis remain important risk factors for death, and once infections are established on biomaterial surfaces they usually persist despite prolonged antimicrobial therapy. This paper covers the topic of infection in mechanical circulatory support. Methods to prevent and manage infection are described. Recent information from the field of microbiology that is relevant to understanding device-related infection is reviewed, including the mechanisms for microbial adhesion to prosthetic surfaces, quorum sensing, and biofilm formation. Characteristics that are important to antimicrobial resistance of microbes dwelling in biofilms are described (e.g. responses to microenvironmental conditions that result in resistance to antibiotics). This information may lead to new therapies that further diminish rates of device infection, and allow complete eradication of infections when they occur.

Cardiomyopathy in a carrier of Duchenne's muscular dystrophy.

During the third trimester of her pregnancy, a 25-year-old carrier of Duchenne's muscular dystrophy developed severe cardiac failure and required mechanical circulatory support and transplantation. Her cardiac function improved during 311 days of circulatory support. However this improvement was not sufficient to allow removal of her left ventricular assist device before transplantation.

Alabama coronary artery bypass grafting project: results of a statewide quality improvement initiative.

CONTEXT: Efforts to improve quality of care in the cardiac surgery field have focused on reducing the risk-adjusted mortality associated with common surgical procedures, such as coronary artery bypass grafting (CABG). However, the best methodological approach to improvement is under debate. OBJECTIVE: To test an intervention to improve performance of CABG surgery. DESIGN AND SETTING: Quality improvement project based on baseline (July 1, 1995-June 30, 1996) and follow-up (July 1-December 31, 1998) performance measurements from medical record review for all 20 Alabama hospitals that provided CABG surgery. PATIENTS: Medicare patients discharged after CABG surgery in Alabama (n = 5784), a comparison state (n = 3214), and a national sample (n = 3758). INTERVENTION: Confidential hospital-specific performance feedback and assistance with multimodal improvement interventions, including the option to share relevant experience with peers. MAIN OUTCOME MEASURES: Duration of intubation, reintubation rate, aspirin therapy at discharge, use of the internal mammary artery (IMA), hospital readmission rate, and risk-adjusted in-hospital mortality. RESULTS: Proportion of extubation within 6 hours increased from 9% to 41% in Alabama, decreased from 40% to 39% in the comparison state, and increased from 12% to 25% in the national sample. Use of IMA increased from 73% to 84%, 48% to 55%, and 74% to 81%, respectively, in the 3 samples, but aspirin use increased only in Alabama (from 88% to 92%). The amount of improvement in all 3 of these process measures was greater in Alabama than in the other samples (IMA use for Alabama vs comparison state was P =.001 and for Alabama vs national sample, P =.02; and P<.001 for all other comparisons). Risk-adjusted mortality decreased in Alabama (4.9% to 2.9%), but this decrease was not statistically significantly different from mortality changes in the other groups (odds ratio, 0.76; 95% confidence interval, 0.54-1.07 vs national sample). CONCLUSION: Confidential peer-based regional performance feedback and process-oriented analysis of shared experience are associated with some improvement in quality of care for patients who underwent CABG surgery.

Fungal infections in ventricular assist devices.

Device infections in patients supported by a mechanical circulatory support system remain an important problem, particularly as we enter the era of permanent device implantation. This article focuses on fungal infections that occur in patients with ventricular assist devices. The nature of fungal, especially Candida species, colonization and infection in severely ill, hospitalized patients will be described. Information regarding the effect of the artificial surface-blood interface on the immune system's ability to combat fungal organisms will also be presented. Basic aspects of the fungal-host interaction serve as the foundation for a discussion of clinical management protocols for preventing and treating fungal infections in patients supported by a ventricular assist device.

Prophylactic value of preincision intra-aortic balloon pump: analysis of a statewide experience.

OBJECTIVE: The objective of this study was to determine whether preincision use of an intra-aortic balloon pump improves survival and shortens postoperative length of stay in hemodynamically stable, high-risk patients undergoing coronary artery bypass grafting. METHODS: A post hoc analysis of the Alabama CABG Cooperative Project database was performed by using propensity scores to model the likelihood of receiving a prophylactic preincision intra-aortic balloon pump. Every patient receiving a prophylactic preincision balloon pump was matched with another patient of similar propensity score who did not receive one. We then compared outcomes for matched pairs. RESULTS: There were 7581 patients of whom 592 received a prophylactic preincision balloon pump. Patients with preoperative renal insufficiency, heart failure, or left main coronary artery disease, or who had undergone previous bypass grafting were significantly more likely to receive a prophylactic preincision balloon pump. By using propensity scores, we matched 550 patients who received a prophylactic preincision balloon pump with 550 who did not. Survival did not significantly differ by whether a prophylactic preincision balloon pump was used. However, surviving patients who received a preincision balloon pump had a significantly shorter postbypass length of stay (7 +/- 7.3 days) than did matched patients not receiving a balloon pump (8 +/- 6.2 days; P <.05). CONCLUSIONS: No survival advantage was found for use of a prophylactic intra-aortic balloon pump in hemodynamically stable, high-risk patients undergoing bypass grafting, as opposed to placing a balloon pump on an "as needed" basis during or after the operation. However, the patients receiving the balloon pump had improved convalescence as shown by significantly shorter length of stay.

Aortic dissection with intimal intussusception: diagnosis and management.

A man presented with acute chest and back pain with loss of consciousness. CT scan showed a mass in the arch that extended into the descending aorta. A diagnosis of type I aortic dissection was ultimately made by echocardiography. At surgery there was a circumferential intimal tear in the aortic root, and an intussuscepted dissection flap was retrieved from the arch and descending aorta.

Pneumoperitoneum after concomitant resection of the right middle and lower lobes (bilobectomy).

BACKGROUND: Removal of the right middle and lower lobes often leaves a pleural space problem that can cause prolonged air leaks. METHODS: A single surgeon prospectively randomized 16 patients who underwent bilobectomy. Eight patients had 1200 mL of air injected under the right hemidiaphragm after bilobectomy and 8 did not. The air was injected through a small transdiaphragmatic opening made in the right hemidiaphragm at the time of pulmonary resection. RESULTS: The age of the patients, preoperative pulmonary function, preoperative comorbidities, indications for surgery, and final pathology were not significantly different between the two groups. On postoperative day #1, a pneumothorax was present in 1 patient (13%) in the pneumoperitoneum group (P group) and in 4 patients (50%) in the nonpneumoperitoneum group (N-P group). On postoperative day 1, an air leak was present in 1 patient (13%) in the P group and 5 patients (63%) in the N-P group (p < 0.001). By the third postoperative day, no patient in the P group had an air leak; however, a leak was present in 4 patients (50%) in the N-P group (p < 0.001). Median hospital stay in the P group was 4 days (range, 3 to 6 days), compared with 6 days (range, 4 to 8 days) in the N-P group (p < 0.001). Three patients in the N-P group were sent home with a Heimlich valve. There was no operative mortality and no complications from the pneumoperitoneum. CONCLUSIONS: We conclude that pneumoperitoneum after bilobectomy is safe and easy to do. It decreases the incidence of air leaks and of pneumothoraces and shortens hospital stay without increasing morbidity. We recommend pneumoperitoneum after bilobectomy at the time of thoracotomy, especially if there are residual small air leaks that cannot be sealed before chest closure.

Cost-benefit analysis of extended antifungal prophylaxis in ventricular assist devices.

This report defines the cost and benefit of extended antifungal prophylaxis in ventricular assist device (VAD) patients (pts). Extended antifungal prophylaxis is defined as prophylaxis with fluconazole or nystatin that is given until pts are extubated and off antibiotics. These data are compared with that obtained from earlier VAD patients who only received anti-fungal drugs for documented fungal colonization or infection. Thirty-six patients had HeartMate (n = 15) or Thoratec (n = 21) VADs between 1989 and 1997. Cultures positive for fungus (n = 52 cultures) were obtained from 16 of 36 patients (44% of patients). Forty-three fungal cultures were in the preprophylaxis and nine in the postprophylaxis era. There was one death attributable to fungal sepsis in the preprophylaxis era and none in the postprophylaxis era. The total cost of antifungal drugs in the preprophylaxis era was $3,840 over 1,498 patient days (PD) (mean $2.56 per PD), versus $70,670 over 1,525 PD in the postprophylaxis era (mean $46.34 per PD). Extended antifungal prophylaxis was not cost effective in VAD patients at this institution. However, short-term perioperative antifungal prophylaxis was not addressed by this study. We are now using short-term antifungal prophylaxis with fluconazole and nystatin in VAD patients because of the potential for serious morbidity and mortality that is associated with fungal device infections. A future analysis will determine the usefulness of this change in strategy.

Controlled postcardioplegia reperfusion: mechanism for attenuation of reperfusion injury.

OBJECTIVE: Controlled reperfusion and secondary cardioplegia are used to minimize reperfusion injury. The mechanisms for their benefit are incompletely defined and may include attenuation of myocyte sodium uptake. METHODS: Pigs had 1 hour of cardioplegic arrest followed by reperfusion with blood (control) or warm cardioplegic solution followed by blood (test). Reperfusion injury in the control and test groups was quantified by measuring changes of intramyocyte ion content with atomic absorption spectrometry and by analyzing electrophysiologic recovery from recordings of reperfusion arrhythmias. RESULTS: Control animals had an increase in intramyocyte sodium content at 5 minutes after initiating reperfusion (+20.2 micromol/g dry weight, P <.04), whereas the test group had an insignificant decrease (-14.0 micromol/g dry weight, P =.33). The first rhythm after initiating reperfusion was more often ventricular fibrillation in the control group (100% vs 50%, P <.02), and the control group required more defibrillations to establish a nonfibrillating rhythm (4.5 +/- 1.2 vs 1.1 +/- 0.3, P <.03). CONCLUSIONS: Controlled reperfusion eliminated the increase in intramyocyte sodium that was observed in the control group at 5 minutes after cardioplegic arrest. This improvement in myocyte ion homeostasis during postcardioplegia reperfusion was associated with fewer reperfusion arrhythmias. These data support the hypothesis that attenuation of myocyte sodium gain during postischemic reperfusion is a mechanism by which controlled reperfusion and secondary cardioplegia are beneficial.

Right thoracotomy for mitral reoperation: analysis of technique and outcome.

BACKGROUND: This report describes technical details of the right thoracotomy approach for mitral surgery, and analyzes our experience with this procedure for patients with a prior sternotomy. Three methods for myocardial management (hypothermic cardioplegic arrest, beating heart, and fibrillating heart) are compared. METHODS: Records were abstracted of patients who had a right thoracotomy between January 1, 1992 and July 1, 1999 for mitral surgery after at least one prior sternotomy. Demographic, operative, and outcome data were collected for analysis. Telephone follow-up was used to measure postoperative New York Heart Association functional status. RESULTS: Eighty-four patients (mean age 60 +/- 15 years) had reoperative mitral surgery via a right thoracotomy. Myocardial management included ventricular fibrillation in 10 patients, operation on the beating heart in 58 patients, and hypothermic blood cardioplegia arrest in 16 patients. The mean time in the operating room was 185 +/- 73 minutes, and the mean duration of cardiopulmonary bypass was 63 +/- 56 minutes. There were no perioperative strokes and the prevalence of death for patients who received cardioplegic arrest was significantly higher than the prevalence of death for patients who had mitral surgery with perfused fibrillating or beating heart techniques (p = 0.007; Fisher's exact test comparing risk-unadjusted mortality). CONCLUSIONS: Right thoracotomy provides efficient exposure for reoperative mitral surgery. Mitral valve procedures on the fibrillating or beating heart are feasible in most patients and are at least as safe as surgery using cardioplegic arrest.

Novel methods to evaluate controlled reperfusion techniques in cardiac surgery.

BACKGROUND: This manuscript describes two novel techniques that may be useful for comparing methods to reperfuse the heart during cardiac operations. These techniques are based on measurements of intra-myocyte ion content and the analysis of reperfusion arrhythmias. METHODS: Myocyte ion content was measured in normal porcine hearts before and after ischemia (cardioplegic arrest, CP arrest) using atomic absorption spectroscopy. A cobalt-EDTA complex served as the extra-cellular marker. Cobalt-EDTA was infused into the aorta together with blood or cardioplegia (CP) solution. Myocardial biopsies were taken prior to CP arrest and upon successful defibrillation 5 min after initiating reperfusion. Ventricular fibrillation (VF) was recorded prior to ischemia, and then during reperfusion. VF wavefront (WF) morphology and propagation patterns were analyzed using computer algorithms. Electrophysiologic variables for measuring VF included the multiplicity index (a descriptor of VF organization), the number of WFs detected (nwaves/s) and the mean peak first derivative of electrogram voltage with respect to time (mp d V/dt). RESULTS: Intra-cellular sodium content increased, while intra-cellular magnesium content decreased between control and reperfusion measurements (p < 0.05). Electrophysiologic recovery was characterized by increasingly rapid depolarization (i.e. more negative mp d V/dt) and an increasing nwaves/s during the first minute of post-CP reperfusion. CONCLUSIONS: Atomic absorption spectroscopy and computer-based analysis of reperfusion VF successfully measured metabolic and electrophysiologic events that occurred during controlled reperfusion. These methods may be useful for comparing controlled reperfusion techniques.

Alabama coronary artery bypass grafting Cooperative Project: baseline data. Alabama CABG Cooperative Project Study Group.

BACKGROUND: The Alabama Cooperative CABG Project is a statewide process-oriented analysis of coronary artery bypass grafting (CABG). The purpose of this report is to present the first information generated by this analysis, which will serve as a baseline for subsequent quality improvement projects. METHODS: Medical records of Medicare beneficiaries from Alabama, a comparison state, and a national random sample who had isolated CABG between July 1, 1995, and June 30, 1996, were examined. Fifty-six demographic, procedural, and outcome variables were abstracted. Quality indicators identified by the Alabama Quality Assurance Foundation Study Group included: internal mammary artery use, prescription of aspirin at discharge, duration of postoperative intubation, use of intraaortic balloon pump, readmission to intensive care unit, hospital readmission within 30 days, return to the operating room for bleeding, and in-patient mortality. Benchmark performance rates for quality indicators reflecting care processes were calculated. RESULTS: Alabama, the comparison state, and the national sample consisted of 4,092, 2,290, and 1,119 patients, respectively. The processes of care and outcome, including risk-adjusted mortality, for CABG across the state of Alabama are generally similar to other states and nationwide samples. However, there was considerable variation at the local hospital level in Alabama for each quality indicator. CONCLUSIONS: The data provide a "snapshot" of practice patterns for CABG in Alabama. A specific quality indicator (duration of intubation) was identified as a focus for statewide improvement. Hospital-specific variations in quality indicators suggested opportunities for improvement in other indicators at a number of hospitals.

Management of wound and left ventricular assist device pocket infection.

Our patient developed a wound infection that involved an implanted left ventricular assist device. At surgery, the pump was washed with a detergent-containing bacteriocidal solution, then antibiotic-impregnated polymethylmethacrylate beads were placed around the pump. The wound was revised using rectus muscle to cover the pump. The incisions have healed and the patient is now at home. She is on no systemic antibiotics and has no evidence of infection 11 months postoperatively.

Infection during circulatory support with ventricular assist devices.

BACKGROUND: This study is a retrospective analysis of infections in patients supported by ventricular assist devices (VADs) as a bridge to cardiac transplantation. METHODS: Infections were assigned to four classes. Class I were patient-related nonblood infections, class II were blood-borne infections, class III were percutaneous site infections, and class IV were infections of intracorporeal VAD components. RESULTS: The cumulative number and incidence of infections were higher during the early VAD experience than in more recent patients (p < 0.05), although the cumulative number and incidence of class II and IV infections were similar in earlier and later patients. There were 28 serious (ie, class II and IV) infections in 9 patients who died, and 35 serious infections in 11 patients who survived until transplantation. Three of 4 patients with class IV infections died. A larger cumulative number of infections (ie, total class I-IV) was associated with more fungal isolates (p < 0.001) and more class II and IV infections (p < 0.02). Positive fungal cultures were obtained in 16 patients, but there were only 3 class III and 1 class IV fungal isolates. CONCLUSIONS: Infection remains an important problem for patients with VADs. Bloodstream infections (class II) can often be controlled by appropriate therapy. However, intracorporeal device infections (class IV) are associated with substantial morbidity and mortality. Optimal implant techniques together with optimal wound care, appropriate use of prophylactic antibiotics, and avoidance of infection in indwelling catheters remain the most practical means for minimizing the risk of VAD infection.

Outcome after myocardial revascularization and renal transplantation: a 25-year single-institution experience.

BACKGROUND AND OBJECTIVE: Cardiac disease is a common cause of death in renal transplant recipients. This study retrospectively analyzes the results of myocardial revascularization procedures in these patients and makes recommendations for managing coronary atherosclerosis in patients with renal disease who already have a transplanted kidney or who may receive a kidney transplant. METHODS: Patients who had myocardial revascularization (coronary artery bypass grafting [CABG] or percutaneous transluminal coronary angioplasty [PTCA]) and renal transplantation at the authors' institution between 1968 and 1994 were analyzed. Patient, procedural, and institutional variables were used for actuarial analyses of survival, as well as multivariate analyses of risk factors for death. RESULTS: Eighty-three of 2989 renal transplant patients required myocardial revascularization either before or after their transplant, and diabetes mellitus was the cause of renal failure in 42% of these patients. Standard coronary angiography, CABG, and PTCA techniques were used without periprocedural renal allograft loss. Actuarial patient survival was 89%, 77%, and 65% at 1, 3, and 5 years after the last procedure (transplantation or revascularization). Cardiac disease was the most common mode of death. Early-phase risk factors for death by multivariate analysis included hypertension and revascularization before 1989. Late-phase risk factors for death included diabetes mellitus, higher number of pre-CABG myocardial infarctions, renal transplantation before 1984, older age, and unstable angina before CABG. CONCLUSIONS: Myocardial revascularization can be performed with acceptable short- and long-term results in patients with renal disease who have renal transplantation either before or after the revascularization procedure. Diabetes mellitus was a highly prevalent condition among these patients, and cardiac disease was their most common mode of death. PTCA and CABG, as performed at this institution, posed little risk for renal allograft loss. Modification of risk factors for coronary atherosclerosis, rigorous cardiac evaluation of patients at risk for coronary artery disease before renal transplantation, and aggressive use of revascularization procedures to decrease the incidence of myocardial infarction are proposed as ways to prolong the survival of renal transplant patients with ischemic heart disease.

Arrest duration influences postcardioplegia electrophysiologic recovery and reperfusion arrhythmias.

BACKGROUND: This study tests the hypothesis that postcardioplegia electrophysiologic recovery is influenced by the duration of cardioplegic arrest. METHODS: Pigs were randomized to various durations of cardioplegic arrest (group I, 15 minutes; group II, 60 minutes; group III, 120 minutes). Electrophysiologic data included limb lead, atrial and ventricular epicardial, and ventricular endocardial electrocardiograms. Variables included times for earliest electrical activity and sinus rhythm; number of defibrillations; mechanism for reperfusion ventricular fibrillation; and time until last ventricular fibrillation. RESULTS: Time to last ventricular fibrillation was 73+/-8, 134+/-23, and 238+/-23 seconds for groups I, II, and III (mean+/-standard error of the mean; p < 0.05 between group III versus groups I and II). The number of defibrillations was 1.0+/-0.3, 5.8+/-1.2, and 10.5+/-1.1 for groups I, II, and III (p < 0.05 between groups). The time to sinus rhythm was 66+/-8, 192+/-27, and 249+/-23 seconds for groups I, II, and III (p < 0.05 group I versus groups II and III). The most common mechanism for reperfusion arrhythmias was an accelerating ventricular tachycardia that initiated fibrillation (79 of 167 episodes). However, in many instances postdefibrillation amplifier saturation masked the initiation of reperfusion arrhythmias. CONCLUSIONS: Electrophysiologic recovery after cardioplegic arrest is influenced by the duration of cardioplegic arrest.

Evaluation of complex mediastinal masses by magnetic resonance imaging.

MRI was used to diagnose a mediastinal mass in a elderly patient with previous repair of aortic coarctation. MRI excluded aneurysm by demonstrating a homogeneous mass encasing aorta and the bypass graft. A second thoracotomy was avoided. Moreover, outpatient testing was performed, without exposure to contrast agents, ionizing radiation, or an invasive procedure.