Five-box thoracoscopic maze based on the Gemini-S bipolar ablation device to treat atrial fibrillation.

Thoracoscopic atrial fibrillation ablation seeks to replicate the electrophysiological effects of more invasive, open surgical procedures. The authors present a lesion concept that includes isolation of the pulmonary veins, the left atrial posterior wall, and the superior vena cava, respectively, lines to inhibit perimitral and periauricular flutter circuits, and left atrial appendage closure. All lesions are tested for bidirectional block.

Outcome of medical therapy, repeat intervention, and mitral valve surgery after failed MitraClip therapy.

OBJECTIVES: Optimal treatment for residual mitral regurgitation (MR) after MitraClip failure is not clearly defined. We report our clinical experience and discuss treatment options. METHODS: Between January 2013 and January 2018, 37 patients (75 ± 8.9 years, 46% male) were admitted for symptomatic MR (grade 3.1 ± 0.47) diagnosed after previous MitraClip therapy. Clinical outcome of these patients, who underwent medical therapy alone (n = 8, M-group), repeat MitraClip therapy (n = 8, reMC group), or mitral valve surgery (n = 21, S-group) for residual MR, were retrospectively analyzed. RESULTS: Thirty-day survival was 88% (M-group), 100% (reMC-group), and 76% (S-group). The rate of discharge to home was 88% in the reMC-group, better than 38% in the M-group (p = 0.051) and 19% in the S-group (p < 0.001). Perioperative non-survivors in the S-group had high surgical risk with median logistic EuroSCORE of 64.6% (interquartile range 57.4%-87.0%); all died from low cardiac output syndrome or multiple organ failure. The main MR pathologies resulted from leaflet tear and tethering in the M-group, tethering in the reMC-group, and degenerative valve and leaflet tear in the S-group. Kaplan-Meier analysis of overall survival at 1 year showed better outcome for patients in the reMC-group (50%, 95% CI 15.2-77.5%) and S-group (47.6%, 95% CI 25.7-66.7%), as compared to those in the M-group (12.5%, 95% CI 0.70-42.3%) (log-rank test p = 0.108 and p = 0.167, respectively). CONCLUSION: Medical therapy alone after failed MitraClip therapy resulted in poor 1-year prognosis. In patients without extremely high surgical risk, repeat MitraClip therapy, or surgical revision MIGHT BE CONSIDERED depending on valve pathology and cardiac comorbidities.

Outcome comparison of mitral valve surgery and MitraClip therapy in patients with severely reduced left ventricular dysfunction.

AIMS: The aim of this study was to compare the outcomes of surgical mitral valve repair or replacement (sMVR) and percutaneous edge-to-edge repair using MitraClip (pMVR) in patients with severe left ventricular dysfunction affected by functional mitral regurgitation (FMR). METHODS AND RESULTS: We retrospectively identified 132 patients with left ventricular ejection fraction (LVEF) â‰¦ 30% submitted to sMVR (n = 47) or pMVR (n = 85) for FMR at our centre from January 2013 to December 2017. To adjust for baseline imbalances, we used a propensity score matching by age, logistic EuroSCORE, and left ventricular end-systolic volume. After being matched, MitraClip therapy showed lower perioperative mortality and rate of complications yet increased residual mitral regurgitation (MR) grade than did surgery (0.2 ± 0.50 in sMVR vs. 1.3 ± 0.88 in pMVR, P < 0.0001). According to stratified multivariate Cox model analysis, residual MR severity was an independent risk factor for cardiac death [hazard ratio (HR), 2.81; 95% confidence interval [CI], 1.44-5.48, P = 0.0025] and re-hospitalization for heart failure (HR, 3.07; 95% CI, 1.50-6.29, P = 0.0022) at 1 year follow-up. Stratified multivariable Cox regression analysis at 3 years identified pMVR as risk factor for cardiac death (HR, 0.19; 95% CI, 0.040-0.86, P = 0.031) and re-hospitalization for heart failure (HR, 0.28; 95% CI, 0.077-0.99, P = 0.048). CONCLUSIONS: In patients with FMR and LVEF ≤ 30%, MitraClip therapy resulted in lower perioperative complications and mortality than sMVR. However, surgically treated patients who survived the perioperative stage had less residual MR and experienced lower rates of re-hospitalization for heart failure at 1 year and lower cardiac mortality at 1 and 3 years of follow-up than did patients undergoing pMVR.

Left-thoracoscopic Convergent ablation for atrial fibrillation.

Epicardial Convergent ablation followed by endocardial touch-up and an additional ablation may be superior to catheter-based interventions in patients with persistent atrial fibrillation. We sought to extend the epicardial lesion set by changing the standard subxiphoid thoracotomy to a left-lateral, totally thoracoscopic approach. This tutorial depicts a closed-chest, beating-heart procedure, including ablation of the left atrial posterior wall, the left atrial dome, and the left pulmonary veins. The left atrial appendage is closed using an epicardial occlusion device.

EuroSCORE-predicted mortality and surgical judgment for interventional aortic valve replacement.

BACKGROUND AND AIM OF THE STUDY: Transcatheter aortic valve implantation (TAVI) is used as an alternative to conventional surgery in high-risk patients. The EuroSCORE quantifies the risk, and patients are selected for this procedure if their predicted mortality is high. The study aim was to evaluate the risk discrimination and calibration of the EuroSCORE, as well as the surgical judgment that is used when selecting the aortic valve replacement (AVR) approach. METHODS: Between 2003 and 2006, a total of 2757 patients underwent isolated, open AVR. The EuroSCORE was compared to the observed in-hospital mortality. A survey among surgeons assessed the relevance of patient-specific factors towards the approach of TAVI versus open AVR. RESULTS: Survivors of AVR had a lower additive EuroSCORE than non-survivors (7.2 +/- 3.34 versus 12.0 +/- 3.34; p < 0.001). The EuroSCORE demonstrated reasonable risk stratification (c-statistic 0.843, p < 0.001). However, none of the 67 non-survivors was correctly predicted (Hosmer-Lemeshow test; p < 0.001), and most patients with a high EuroSCORE survived AVR. The actual mortality was 2.8% as compared to a EuroSCORE-predicted mortality of 12.5 +/- 14.2% (p < 0.001). This poor calibration was worse with higher EuroSCOREs (Cusum test; p < 0.001). Surgeons identified a porcelain aorta as the only factor that warranted TAVI. Most EuroSCORE variables had either no relevance for treatment selection, or prompted open AVR. CONCLUSION: Patient selection for TAVI cannot be based on the EuroSCORE, because it lacks discrimination and center-specific calibration. Thus, individual, surgical judgment that weighs institutional expertise for high-risk patients against a possible reduction of mortality by using interventional techniques, is recommended.

[Electromyostimulation (EMS) in cardiac patients. Will EMS training be helpful in secondary prevention?]. / Elektromyostimulation (EMS) bei kardiologischen Patienten. Wird das EMS-Training bedeutsam für die Sekundärprävention?

BACKGROUND: Current guidelines concerning the treatment of patients with chronic congestive heart failure (CHF) include ergospirometry-directed dynamic exercises on a daily basis. Several prospective, randomized trials have confirmed its positive influence on clinical symptoms and prognosis of the disease. Patients with stable coronary artery disease (CAD) can benefit from a 27% reduction of mortality, as shown in meta-analyses of several studies. By contrast, patients with CHF have traditionally been discouraged from physical activities, which may have had detrimental consequences. They became even less able to participate in daily activities that in turn hastened the disease-driven atrophies of skeletal muscles. On the other hand, well-adjusted endurance training at 50-70% of maximum oxygen uptake was shown to improve overall fitness. In a recent metaanalysis, the mortality of patients with CHF was reduced by 35% by sports, and the rate of hospitalizations dropped by 28%. It is a well-perceived clinical problem that successful treatment is not possible without intensive guidance and a close therapeutic relationship. Being left in their routine situation and circumstances, the majority of patients cannot cope with the day-to-day challenge of an independent, active lifestyle. Among the primary reasons not to sustain physical activity are mental, psychological or social barriers. PATIENTS AND METHODS: The authors have begun, in a cohort of patients with CHF, a prospective pilot study to investigate the impact of, and attitude to, electromyostimulation (EMS). Unique features of this treatment include its passive nature that remains independent of mental attitude. RESULTS: An up to 96% increase of peak oxygen uptake at the anaerobic threshold could be shown (pre- vs. posttraining phase, VO(2at) 19.39 [+/- 5.3] ml/kg vs. 24.25 [+/- 6.34] ml/kg). The diastolic blood pressure decreased significantly. A 14% gain in muscle volume was observed, while overall body weight remained unchanged. All patients kept up the training until the conclusion of the study and found their overall fitness to be considerably improved. CONCLUSION: The results may indicate the enormous potential of EMS for the treatment of patients within the cardiologic arena, especially those with CHF.

Dissociation between vascular endothelial growth factor receptor-2 and blood vessel density in the caudate nucleus after chronic hydrocephalus.

Chronic hydrocephalus (CH) is characterized by the presence of ventricular enlargement, decreased cerebral blood flow (CBF), and brain tissue oxygen delivery. Although the underlying pathophysiological role of vascular endothelial growth factor (VEGF) is not clear, ischemic-hypoxic events in CH are known to trigger its release. Previously, we have shown increased VEGF receptor-2 (VEGFR-2) and blood vessel density (BVd) in the hippocampus after CH. We investigated changes in neuronal and glial VEGFR-2 density and BVd in the caudate nucleus in an experimental model of CH. Animals with CH were divided into short term (ST, 2 to 4 weeks) and long term (LT, 12 to 16 weeks) and were compared with surgical controls (SCs, 12 to 16 weeks). The cellular and BVds were estimated using immunohistochemical and stereological counting methods. Overall, percentage (%)VEGFR-2 neurons were approximately two times greater in CH (ST, LT) than in SC. By comparison, glial cell %VEGFR-2 was greater by 10% to 17% in ST and 4% to 11% lower in LT compared with that in SC. Blood vessel density was significantly lower in CH than in SC in the superficial caudate. Changes in cerebrospinal fluid ventricular volume and pressure, as well as in CBF did not correlate with either VEGFR-2 or BVd. These observed findings suggest that destructive forces may outweigh angiogenic forces and possibly show a disassociation between VEGFR-2 and BV expressions.

Surgical removal of occluder devices: complications and pitfalls.

Interventional closures of atrial septal defects (ASDs) and paravalvular leaks represent attractive treatment options to prevent surgical procedures. Nevertheless, a small number of complications or pitfalls remain after interventional closure of ASDs or paravalvular leaks that require surgical therapy. We report on 3 cases in which surgery was necessary after attempts to close a paravalvular leak. A mechanical valve prosthesis in the mitral position was explanted from a 73-year-old man because of increasing hemolysis and restriction of the motion of one leaflet by the occluder device. A 21-year-old woman with 3 previous surgeries for truncus arteriosus communis type 1 developed paravalvular leakage after replacements of the pulmonary and aortic valves. Although aortic insufficiency was reduced to grade I by placing 2 Amplatzer occluders, significant hemolysis developed. A 24-year-old woman had previously undergone 3 cardiac surgeries (commissurotomy at the age of 5 years for aortic stenosis, followed by aortic valve replacements at 13 and 14 years of age). The patient developed severe hemolysis after interventional closure. A redo aortic valve replacement was performed for the fourth time. As in the previous 2 cases, the surgery for this challenging case and the postoperative course went well. We also present 6 cases in which the occluder was explanted because of dislocation, thrombus formation, irritation of the aortic root, or systemic allergic reaction to the percutaneous occluder after initial closure of the ASD. The intra- and postoperative courses were uneventful in all cases. In summary, surgery for complications or pitfalls after interventional closure of paravalvular leaks or ASDs is challenging and carries a high risk in cases of paravalvular leaks. Nevertheless, the outcomes of the presented cases were uneventful. In the future, the development of a more suitable device technology may improve the results of interventional procedures, especially in cases of paravalvular leaks.

International normalized ratio self-management lowers the risk of thromboembolic events after prosthetic heart valve replacement.

BACKGROUND: Although prosthetic valves are durable and easy to implant, the need for lifetime warfarin-based anticoagulation restricts their exclusive usage. We investigated if anticoagulation self-management improves outcome in a single-center series. METHODS: Between 1994 and 1998, 765 patients with prosthetic valve replacements were prospectively enrolled and randomized to receive conventional anticoagulation management by their primary physician (group 1, n = 295) or to pursue anticoagulation self-management (group 2, n = 470). A study head office was implemented to coordinate and monitor anticoagulation protocols, international normalized ratios (INR), and adverse events. Patients were instructed on how to obtain and test their own blood samples and to adjust warfarin dosages according to the measured INR (target range, 2.5 to 4). RESULTS: Mean INR values were slightly yet significantly smaller in group 1 than in group 2 (2.8 +/- 0.7 vs 3.0 +/- .6, p < 0.001). Moreover, INR values of patients with conventional INR management were frequently measured outside the INR target range, whereas those with anticoagulation self-management mostly remained within the range (35% vs 21%, p < 0.001). In addition, the scatter of INR values was smaller if self-managed. Freedom from thromboembolism at 3, 12, and 24 months, respectively, was 99%, 95%, and 91% in group 1 compared with 99%, 98%, and 96% in group 2 (p = 0.008). Bleeding events were similar in both groups. Time-related multivariate analysis identified INR self-management and higher INR as independent predictors for better outcome. CONCLUSIONS: Anticoagulation self-management can improve INR profiles up to 2 years after prosthetic valve replacement and reduce adverse events. Current indications of prosthetic rather than biologic valve implantations may be extended if the benefit of INR self-management is shown by future studies with longer follow-up.

Patient self-monitoring of prosthetic heart valve function.

BACKGROUND AND AIM OF THE STUDY: Prosthetic heart valve dysfunction impacts on morbidity and quality of life. Although the diagnosis can be made by imaging studies, clinical symptoms commonly precede the diagnostic work-up. The ThromboCheck device analyzes the sound frequency spectra of valve motion, and alterations due to valve dysfunction are observed before overt clinical symptoms develop. The study aim was to determine if the ThromboCheck can be used to monitor the prosthetic valve function of patients at home. METHODS: Between 2003 and 2007, a total of 541 prosthetic heart valve recipients was prospectively enrolled into a double-blind, multi-center study. ThromboCheck devices were used to evaluate the sound frequency phenomena of valve motion. If the sound frequency spectra deviated from baseline, alarm signals were returned to the medical center via telephone, and these prompted evaluation by fluoroscopy and echocardiography. The clinical follow up included questionnaires at regular intervals. RESULTS: The cumulative observation period exceeded 748 patient-years, with a median follow up of 25.2 months per patient (range: 1 to 36 months). Almost all patients used the device at least two to three times per week to evaluate valve function, and the vast majority found it easy to operate. About 135,000 codes were returned to the study centers for further analysis; of these codes, 30 (0.0002%) were alarm signals. On 29 of the 30 occasions, prosthetic valve dysfunction was confirmed by fluoroscopy and echocardiography, yielding positive predictive values and specificities of 97% and 100%, respectively. There was no clinical event in the absence of a ThromboCheck alarm signal. Thrombolysis or increased warfarin-based anticoagulation quickly restored the initial sound frequency spectrum of the prosthetic valve in 16 patients. Another 13 patients were surgically revised; their prosthetic valves revealed significant thrombi upon replacement. By using the ThromboCheck device as part of a surveillance system, 79% of the patients felt safer with regards to prosthetic valve dysfunction. CONCLUSION: Analysis of sound frequency spectra by the ThromboCheck identified prosthetic heart valve dysfunction before clinical symptoms developed, and promoted early therapy. The restoration of valve function normalized the frequency spectra, which may be utilized to guide treatment. These results justify further efforts to introduce the analysis of sound phenomena into routine clinical care after prosthetic valve implantation.

Monocyte chemotactic protein-3 is a myocardial mesenchymal stem cell homing factor.

MSCs have received attention for their therapeutic potential in a number of disease states, including bone formation, diabetes, stem cell engraftment after marrow transplantation, graft-versus-host disease, and heart failure. Despite this diverse interest, the molecular signals regulating MSC trafficking to sites of injury are unclear. MSCs are known to transiently home to the freshly infarcted myocardium. To identify MSC homing factors, we determined chemokine expression pattern as a function of time after myocardial infarction (MI). We merged these profiles with chemokine receptors expressed on MSCs but not cardiac fibroblasts, which do not home after MI. This analysis identified monocyte chemotactic protein-3 (MCP-3) as a potential MSC homing factor. Overexpression of MCP-3 1 month after MI restored MSC homing to the heart. After serial infusions of MSCs, cardiac function improved in MCP-3-expressing hearts (88.7%, p < .001) but not in control hearts (8.6%, p = .47). MSC engraftment was not associated with differentiation into cardiac myocytes. Rather, MSC engraftment appeared to result in recruitment of myofibroblasts and remodeling of the collagen matrix. These data indicate that MCP-3 is an MSC homing factor; local overexpression of MCP-3 recruits MSCs to sites of injured tissue and improves cardiac remodeling independent of cardiac myocyte regeneration.

Heparin-induced thrombocytopenia in patients receiving mechanical circulatory support.

OBJECTIVES: Patients receiving mechanical circulatory support are at risk for the development of heparin-induced thrombocytopenia due to the prolonged postoperative use of heparin. We evaluated their antibody status and outcome. METHODS: Between 2003 and 2004, 115 patients received mechanical circulatory support for more than 5 days. Blood samples from postoperative day 7 were retrospectively analyzed for anti-platelet factor 4/heparin antibodies and heparin-induced platelet activation. RESULTS: Overall, 12 (10.6%) patients had heparin-induced thrombocytopenia as defined by in vitro platelet activation, 28 (24.8%) had nonactivating antibodies, and 73 (64.6%) were classified as negative for antibodies. Patients positive for heparin-induced thrombocytopenia had the highest levels of anti-platelet factor 4/heparin immunoglobulin G antibodies. Freedom from thromboembolism was 33%, 33%, and 16% at 1, 3, and 6 months for positive patients, 77%, 68%, and 55% for negative patients (P < .001), and 70%, 53%, and 53% for patients with nonactivating antibodies (P = .068), respectively. The relative risk for thromboembolism in antibody positive patients peaked in the first month of support (odds ratio 7.46, P = .002). Independent risk factors for thromboembolic events included higher anti-platelet factor 4/heparin antibody titers, female gender, and higher fibrinogen levels. CONCLUSION: Heparin-induced thrombocytopenia was more prevalent in patients receiving mechanical circulatory support than in other cardiac patients. Frequent antibody screening is recommended due to the increased risk of thromboembolism. Heparin alternatives should be subjected to clinical trials in these high-risk patients.

Transmural distribution of myocardial blood perfusion and phasic coronary blood flow pattern in a canine model of acute ischemia.

BACKGROUND: Although several investigators have analyzed coronary artery blood flow under various conditions, almost all these studies have measured only some branches of the left anterior descending (LAD), left circumflex (LCX), or right coronary (RCA) artery. METHODS: In a canine model of acute ischemia (n = 5), we simultaneously assessed (a) regional myocardial blood perfusion using microspheres and (b) phasic coronary blood flow patterns as measured by three epicardial flow probes placed around the LAD, LCX, and RCA. RESULTS: The results from this study indicated that the LAD supplies blood to the epicardial (r = 0.687, p<0.0001), midwall (r = 0.556, p = 0.0021), and endocardial layers (r = 0.666, p = 0.0001) of the LAD area; the LCX supplies the midwall (r = 0.514, p = 0.0051) and endocardial layer (r = 0.621, p = 0.0004) of the LCX area, antero-lateral papillary muscle (r = 0.548, p = 0.0025), and postero-medial papillary muscle (r = 0.641, p = 0.0002), especially during the diastolic phase; and the RCA supplies the right ventricular apex (r=0.559, p=0.0020), left atrium (r = 0.618, p = 0.0005), right atrium (r = 0.471, p = 0.0114), and postero-medial papillary muscle (r = 0.486, p = 0.0088), especially during the systolic phase. CONCLUSIONS: These results are potentially relevant to understanding the physiology of myocardial blood perfusion and to improving treatment of acute myocardial ischemia and infarction.

Chronic hydrocephalus-induced changes in cerebral blood flow: mediation through cardiac effects.

Decreased cerebral blood flow (CBF) in hydrocephalus is believed to be related to increased intracranial pressure (ICP), vascular compression as the result of enlarged ventricles, or impaired metabolic activity. Little attention has been given to the relationship between cardiac function and systemic blood flow in chronic hydrocephalus (CH). Using an experimental model of chronic obstructive hydrocephalus developed in our laboratory, we investigated the relationship between the duration and severity of hydrocephalus and cardiac output (CO), CBF, myocardial tissue perfusion (MTP), and peripheral blood flow (PBF). Blood flow measures were obtained using the microsphere injection method under controlled hemodynamic conditions in experimental CH (n=23) and surgical control (n=8) canines at baseline and at 2, 4, 8, 12, and 16 weeks. Cardiac output measures were made using the Swan-Ganz thermodilution method. Intracranial compliance (ICC) via cerebrospinal fluid (CSF) bolus removal and infusion, and oxygen delivery in CSF and prefrontal cortex (PFC) were also investigated. We observed an initial surgical effect relating to 30% CO reduction and approximately 50% decrease in CBF, MTP, and PBF in both groups 2 weeks postoperatively, which recovered in control animals but continued to decline further in CH animals at 16 weeks. Cerebral blood flow, which was positively correlated with CO (P=0.028), showed no significant relationship with either CSF volume or pressure. Decreased CBF correlated with oxygen deprivation in PFC (P=0.006). Cardiac output was inversely related with ventriculomegaly (P=0.019), but did not correlate with ICP. Decreased CO corresponded to increased ICC, as measured by CSF infusion (P=0.04). Our results suggest that CH may have more of an influence on CO and CBF in the chronic stage than in the early condition, which was dominated by surgical effect. The cause of this late deterioration of cardiac function in hydrocephalus is uncertain, but may reflect cardiac regulation secondary to physiologic response or brain injury. The relationship between cardiac function and CBF should be considered in the pathophysiology and clinical treatment of CH.

Triple bridge-to-transplant in a case of giant cell myocarditis complicated by human leukocyte antigen sensitization and heparin-induced thrombocytopenia type II.

Bridge-to-bridge experience has documented the feasibility of a switch from short-term to long-term mechanical circulatory support until heart transplant. We describe a case of irreversible cardiogenic shock due to giant cell myocarditis treated consecutively with extracorporal membrane oxygenation, bi-ventricular assist device, and total artificial heart. The postoperative course was complicated by human leukocyte antigen sensitization and heparin-induced thrombocytopenia type II. Our patient successfully underwent heart transplant after 10 months of support and was discharged in good condition. This case illustrates suitable device selection for myocarditis and represents two treatable immunological complications.

Duration of inotropic support after left ventricular assist device implantation: risk factors and impact on outcome.

OBJECTIVES: Because duration of inotropic support after left ventricular assist device implantation has been recognized as a surrogate for right ventricular dysfunction, we sought to (1) identify its preimplantation risk factors, particularly its association with preimplantation right ventricular dysfunction, and (2) assess its impact on clinical outcomes. METHODS: Between 1991 and 2002, left ventricular assist devices were implanted in 207 patients, exclusive of those receiving preoperative mechanical circulatory support, which precluded measuring right ventricular stroke work. Duration of inotropic support was analyzed as a continuous variable, truncated by death or transplantation, and in turn as a risk factor for these 2 events. RESULTS: Inotropic support decreased from 100% on the day of implantation to 57%, 33%, and 22% by days 7, 14, and 21. Its duration was strongly associated with lower preimplantation right ventricular stroke work index, older age, and nonischemic cardiomyopathy and was associated (P < .04) with higher mortality before transplantation but not with transition to transplantation. We identified no preimplantation risk factors for right ventricular assist device use because of its relatively infrequent use in this population (18 patients, only 4 of whom survived to transplantation). CONCLUSION: Duration of inotropic support after left ventricular assist device insertion is strongly correlated with low preimplantation right ventricular stroke work index. In turn, it was associated with reduced survival to transplantation. Thus, right ventricular stroke work measured before implantation might be useful in decision making for biventricular support, destination therapy, or total artificial heart.

Experimental study of new diagnostic system for coronary artery disease using coronary transit index.

OBJECTIVES: Noninvasive cardiac imaging techniques have had an increasing role in the diagnosis of coronary artery disease. However, these techniques are not widely available as a tool in the office setting. The purpose of this study was to provide an accurate assessment of coronary artery disease for screening purposes using Coronary Transit Index (CTI) assessment with small, high-resolution gamma cameras. METHODS: Total coronary blood flow was measured with ultrasonic flow probes placed around the left anterior descending coronary artery, left circumflex coronary artery, and right coronary artery in a total of 33 conditions in 5 healthy mongrel dogs. The coronary blood flow was reduced stepwise with vascular occluders placed around the coronary arteries. The procedure for obtaining CTI included 4 parts: 1) The animal was injected intravenously with a bolus of a radioactive tracer (2.5-5.0 mCi of (99m)Tc-DTPA); 2) Dedicated gamma sensors monitored the passage of the injected bolus; 3) Time-activity curves were measured at the left ventricle with and without its wall; 4) The ratio of the washout rates of the 2 curves determined the CTI. RESULTS: Coronary Transit Index was successfully obtained from the left ventricle. The coronary blood flows measured by flow probes were well correlated with the regional myocardial blood flow. The percentage of the baseline value of the total coronary blood flow had the highest correlation (R=0.807, p<0.0001) with the Coronary Transit Index. CONCLUSIONS: These data indicated that a new diagnostic system using CTI successfully identified reduced coronary blood flow.