Experience of the combined use of the cusp-overlap projection and auricular pacing in transcatheter aortic-valve replacement with the self-expanding valves

Introduction

Need of permanent pacemaker implantation (PPI) continues to be an undesirable side-effect after transcatheter aortic-valve replacement (TAVR), mostly in self-expandable (SE) valves. Recently, different techniques have arisen, as the cusp-overlap projection (COP) to better control TAVR implantation depth, and the sequential atrial pacing (AP) after deployment to test atrioventricular (AV) conduction. However, the combination of both techniques has not been tested yet. We sought to determine if the combination of COP and AP can decrease the need of PPI after SE aortic prothesis.

Methods

We retrospectively studied 253 patients in sinus rhythm who underwent TAVR procedure with SE valves between 2018 and 2021, and compared standard implantation (n=143) with the combined use of COP and AP (n=110). Patients with permanent atrial fibrillation or previous pacemaker were excluded. Assessment included EKG, imaging, immediate and 30-day follow-up. AP was performed after TAVR in the absence of complete AV block at rates of 70 to 120 beats/min (or until AV Block was observed).

Results

Median patient age was 80 [75–85] years old and 52.2% were female. No significant differences could be appreciated in baseline demographics or treatment. Both cohorts had similar EKG intervals and similar rates of conduction disturbances (Table 1). Patients with CO+AP displayed bigger outflow tract perimeters (p=0.003). Also, the CO+AP cohort underwent more frequent predilation prior to valve deployment (p<0.001).

During TAVR complete AV block occurred in 4.6% of the CO+AP cohort vs 14.8% in the standard group (p=0.002). Among patients with transient or no conduction disturbances immediately after deployment, AP showed Wenckebach phenomenon in 22 subjects at a median heart rate of 110 bpm. PPI was considered within 24 hours when Wenckebach phenomenon developed below 90 bpm. Testing atrio-his conduction led to a significant decrease in the next 24-hour surveillance with a temporary pacemaker in the COP+AP cohort (23.1% vs 90.2% in the standard cohort, p<0.0001). Time of hospitalization was significantly reduce in the COP + AP cohort (mean stay 2 [1; 3] days vs 5 [4; 8] days in the standard cohort, p<0.0001), and the total amount of total PPI at that time was still lower CO+AP group (12.7% in CO+AP group vs 21.0% in the standard, p=0.121) (Figure 1).

On a 30-day follow-up, the rate of PPI after TAVR remained significantly decreased in the COP+AP cohort (p=0.039, Figure 1).

Conclusion

Combining COP with AP reduces the need of immediate and short-term PPI and reducing on-admission conduction surveillance and hospitalization stay after self-expandable TAVR.

Funding Acknowledgement

Type of funding sources: None.

Exercise unmasks impaired vascular and cardiac hemodynamic in patients with hypertrophic cardiomyopathy

Background/Introduction

Exertional dyspnea is a common finding in patients with Hypertrophic Cardiomyopathy (HCM), yet little data is available regarding the hemodynamic disturbances that lead to symptom development in this population.

Purpose

To investigate the mechanisms involved in the functional limitation of patients with HCM.

Methods

We prospectively studied 20 symptomatic patients with confirmed diagnosis of HCM. Assessment included NT-pro BNP levels, echocardiogram, and invasive characterization, where subjects also underwent invasive cardiopulmonary exercise testing.

Results

Median patient age was 57 (48–66) years old and 15 (75%) were male. Basal NT-pro BNP was elevated (748 pg/mL [406–1082]) and 8 (40%) subjects had NYHA functional Class III despite optimal medical treatment. Sarcomeric abnormal mutations were identified in 12 subjects (60%), most frequently in MYBPC3. Ultrasound imaging showed marked left ventricle (LV) hypertrophy (LV Mass Index 140 g/m2 [109–161]), with signs of LV outflow obstruction in 13 (65%) subjects. All patients displayed preserved ejection fraction (68% [61–73]). Significant mitral regurgitation was present in 5 subjects and median E/e' was 9.87 [6.43–13.14].

At rest, biventricular filling pressures were relatively normal, with upper limit mean Pulmonary Pressure (Table). Patients exercised for 6.4 (95% CI: 5.6–7.2) min, achieving a respiratory exchange ratio of 1.11 (1.02–1.17). All subjects displayed normal cardiac output at rest (5.6 L/min (3.7–7.5)), that increased during exertion, due mostly to a rise in heart rate (p<0.0001). Exercise doubled LV End-Diastolic Pressure from 15.3 (11.5–19.1) mmHg at baseline to 30.4 (26.6–34.3) mmHg at peak VO2 (p<0.0001), whereas mean pulmonary pressure increased from 21 (14–29) mmHg to 40 (33–47) mmHg (p<0.0001).

Remarkably, although arterial hemodynamics were relatively normal at baseline, exercise induced significant increases both in the continuous (systemic vascular resistance) and pulsatile components of vascular load (Impedances, p<0.05; Table 1) (Figure 1). This increase in afterload during exertion has not been previously documented in HCM. The decreased compliance derived, can also play a role in the elevated filling pressures documented on exertion.

Conclusion

Exercise unmasks adverse hemodynamics in HCM, severely increasing LV filling pressures and showing systemic arterial dysfunction.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Instituto de Salud Carlos III, Spain.

Early results of a simplified protocol over standard in patients undergoing transcatheter aortic-valve replacement

Introduction

Transcatheter aortic-valve replacement (TAVR) procedure has been simplified, being now a less-invasive minimalist strategy the standard of treatment. Therefore, length of hospitalization has decreased, and early-discharge (ED) (<72 hour) protocols are in development.

Lately, additional techniques to optimize TAVR procedure have arisen, such as the use of radial approach as the secondary access, conscious sedation, cusp overlap projection (COP) to better control the implantation depth in self-expanding (SE) valves, or atrial pacing (AP) after deployment to test atrioventricular (AV) conduction. With the combination of these 4 maneuvers, we have developed an ED protocol, and hereby present the immediate results.

Methods

We prospectively studied 176 patients who underwent staged and transfemoral TAVR procedure with our novel protocol between May 2020 and December 2021 (Protocol) and compared them with a retrospective cohort of 175 patients who underwent standard TAVR between January 2018 and April 2020 (Standard). The protocol cohort included the use of conscious sedation with midazolam and fentanyl, routine radial approach as the secondary access, use of the CO projection, and AP after deployment in the absence of complete AV block, at rates of 70 to 120 beats/min (or until AV Block was observed) in 10 beats/min increments for a total of 20 beats at each increment. As part of this protocol, patients remained in general cardiology ward, avoiding ICU stay, with rapid recovery and early mobilization (After 6 hours in the absence of bleeding). In the absence of complications patients were discharged within 24–48 hours and reviewed a week and a month later in clinic. Initial assessment included EKG, echocardiogram, in hospital and 30-day follow-up.

Results

Median patient age was 80 years old and 49.9% were female. Despite higher rates of hypertension in the standard cohort (p=0.038), no significant differences could be appreciated in baseline demographics, EKG or imaging findings (Table).

Even with higher rates of predilation, CO and AP, the length of procedure and the use of contrast was lower in the protocol cohort. Rates of intraprocedural AV block were similar among groups (p=p.21), but AP led to a significant lower need of temporary pacemaker surveillance (p<0.0001). The use of radial access also tend to diminish immediate bleeding and vascular complications.

According to protocol, the median length of stay was reduced to 2 [1; 4] days (p<0.0001).

At a 30-day follow up, the incidence of major adverse cardiac events was low and similar among groups (p=0.67) (Figure), with no significant differences in the incidence of permanent pacemaker implantation, heart failure admission, bleeding o vascular complication (Figure)

Conclusion

A simplified TAVR protocol combining radial access, CO, AP can be adopted safely, leading to TAVR patients early discharge, with no major events on an immediate 30-day follow-up.

Funding Acknowledgement

Type of funding sources: None.

Transcatheter aortic-valve replacement with the self-expanding valve Portico in low-risk patients

Background

In the past years, transcatheter aortic-valve replacement (TAVR) has risen as a feasible and safe option for patients with aortic stenosis, been now an option of treatment in low-risk (Euroscore II <4%) patients over 75 years.1

Evidence of this treatment with self-expandable supraanular bioprothesis Evolut have widely proven to be no inferior to surgical valve replacement.2 Nevertheless, experience of the annular self-expandable prothesis Portico available in this population is scarce.

Purpose

We present our early experience with the annular self-expandable prothesis Portico in our low-risk population.

Methods

We retrospectively studied 219 symptomatic low-risk patients with who underwent TAVR procedure with self-expandable valves between 2018 and 2021. Assessment included echocardiogram, immediate and 30-day follow-up, as well as last clinical visit follow-up. 92 subjects received an annular Portico prothesis. Our reference group was the suprannular prothesis Evolut (n=127), already validated for low-risk patients in clinical trials.2

Results

The mean age of the patients was 79 years, 43.4% were women, and all the patients were at low surgical risk (2.2 [1.6; 3.0]). No significant differences could be appreciated in baseline demographics and echocardiographic characteristics except for body mass index (BMI), which was higher in the Portico group (p<0.001) (Table).

Procedure length was similar, with the particular need of higher predilation in the Portico group according to recommendations. Both self-expandable prothesis had similar rates of intraprocedural atrioventricular block, bleeding, vascular complications, stroke, and new onset atrial fibrillation.

Mean aortic-valve gradients before discharge were lower at the suprannular Evolut group than in the annular Portico group, and immediate residual aortic regurgitation was almost inexistent in both groups (Table 1).

At a 30-day follow up, the incidence of major adverse cardiac events was low and similar among groups (p=0.6) (Figure 1), with no significant differences in the incidence of permanent pacemaker implantation, heart failure admission, stroke, bleeding o vascular complication (Figure 1).

Conclusion

Annular aortic self-expandable prothesis Portico is a feasible alternative for patients with AS and low surgical risk who undergo TAVR procedure.

Funding Acknowledgement

Type of funding sources: None.

Sex differences in patients with ischemia and no obstructive coronary disease subjected to intracoronary acetylcholine test in a multicenter registry

Background

Ischemia with no obstructive coronary disease (INOCA) is increasingly diagnosed because of wide performance of coronary angiography. Prevalence of INOCA is higher in women than in men, however the exact pathophysiological mechanisms which may explain this phenomenon are still not very well understood.

Objective

To evaluate differences in clinical and procedural characteristics between men and women with INOCA subjected to intracoronary acetylcholine test (Ach).

Methods

A total of 210 women and 148 men with INOCA diagnosed with coronary angiography, were prospectively enrolled in a multicenter, observational registry. Ach test was performed according to clinical indications in all included patients. After 1-year patients were re-evaluated for major cardiovascular events, angina symptoms and prescribed medical treatment.

Results

Mean age of 60.6±13.6 years old was similar in both populations, but differences were observed in the prevalence of risk factors: active smoking was more frequent among men (43% vs. 17%, p<0.001), who had also a higher number of associated risk factors (≥3 risk factors were present in 31.2% of men vs. 20.2% of women, p<0.01) and more frequent history of percutaneous coronary revascularization (14.2% vs. 6.7%, p=0.03). Women were more prone to have dyspnea than men (35.5% vs. 20.8%, p=0.01). Men had more coronary atherosclerosis in angiography (57.9% vs. 43.7%, p=0.01) and more slow flow in the left anterior descending artery (21.6% vs. 9.0%, p=0.001). Ach was positive in 36.5% of patients, similar in both sexes, with no differences in the type of induced coronary spasm. Among those with a positive Ach test, at one-year, 36% of women vs. 43.6% of men were on optimal medical treatment for vasospasm although the difference was not statistically significant. Importantly, 41.5% of women and 38.1% of men experienced severe symptoms of angina during follow-up.

Conclusions

Although men with INOCA have a higher risk profile than women and more coronary atherosclerosis, one third of patients present endothelial dysfunction, similar in both groups, indicating that probably other pathophysiological mechanisms are responsible for it in females. Treatment in these patients remains suboptimal and associated with highly impaired quality of life.

Funding Acknowledgement

Type of funding source: None

Clinical profile and predictors of positivity of acetylcholine test in patients with angina and no obstructive coronary artery disease. Results of a multi-center mediterranean registry

Background

Coronary endothelial dysfunction and vasospasm are potential causes of ischemia in no obstructive coronary disease (INOCA) and are now known to be associated with an increased risk of major cardiovascular events (MACE) and impaired quality of life. The recent guidelines recommend the use of intracoronary acetylcholine to unravel the underlying pathophysiology of INOCA, by identifying those with endothelial dysfunction, and to guide future treatment in these patients.

Objective

To evaluate the clinical profile and prevalence of endothelial dysfunction in patients with INOCA, and to identify the predictors of positivity of the acetylcholine test.

Methods

A total of 358 patients with INOCA were prospectively enrolled in a multicenter observational study. Coronary angiography and acetylcholine test were performed according to clinical indications in all included patients. Patients were followed-up for 1-year for MACE and clinical reevaluation of symptoms.

Results

Patients' mean age was 60.6±13.5 y.o. and 58.7% were females, with no previous history of coronary heart disease in 76% of cases. Regarding clinical presentation, 56.9% had angina at rest, 59.9% exertional angina, and 29.5% dyspnea. In 39% the EKG was abnormal, and in 10.9% there was a troponin rise.

Coronary endothelial dysfunction –defined as a vasoconstriction over 30%– was observed in 129 (36%) patients, and severe vasoconstriction (>70%) in 75 (21%). Of positive cases, 47 (36%) focal vasoconstriction, and 90 (70%) diffuse. On follow-up, patients with a positive Ach test were treated differently, with a lower prescription of betablockers (12% vs. 24%, p=0.01) and a higher use of vasodilators (47% vs. 28.5%, p=0.001). Guidelines-recommended optimal treatment was prescribed to 39.2% of patients with a positive acetylcholine test. Patients with positive acetylcholine test were more prone to having worsening angina (25.6% vs. 12.8%, p<0.01) and minimal exertion angina (40% vs. 26.7%, p=0.03) on follow-up. Multivariable regression analysis showed that acetylcholine test positivity was predicted by the presence of diabetes (OR 1.7, p=0.04), exertional angina (OR 1.2, p=0.04), coronary atherosclerosis (OR 1.8, p=0.02) and coronary milking (OR 2.6, p=0.04).

Conclusions

Endothelial dysfunction detected by acetylcholine test was present in one third of patients with INOCA and was associated with more severe and worsening symptoms. Although Ach test positivity influenced the pharmacological treatment at discharge, a large room for optimization still remained.

Funding Acknowledgement

Type of funding source: None

P5621Diagnostic accuracy of resting full-cycle ratio in the non-culprit artery of acute patients

Introduction

Resting full-cycle ratio (RFR) is a novel non-hyperemic index of coronary stenosis severity, independent of the timing within the cardiac cycle. Recent data has demonstrated good correlation between RFR and Fractional Flow Reserve (FFR) in stable coronary disease (SCD). However, there are no data regarding the reliability of RFR in non-culprit arteries of patients presenting with acute myocardial infarction (AMI).

Purpose

To study the diagnostic accuracy of RFR versus FFR in the non-culprit artery in AMI compared to stable lesions.

Methods

RFR, FFR, Coronary Flow Reserve (CFR), Index of Microcirculatory Resistance (IMR), and Resistance Reserve Ratio (RRR) were calculated in 67 patients with AMI and an intermediate lesion in a non-culprit artery (median time from primary PCI to study: 48 hours). Data were compared with those of a retrospective group of 66 patients with SCD.

Results

There was a higher proportion of males among patients of the AMI group (85% vs 62%, p=0.0026). Mean age was 64.5±11 years, being AMI cohort younger at presentation [62±11 vs 67±12 years in SCD cohort (p=0.04)]. Patients with AMI had a significantly lower prevalence of hypertension (52% vs 75%, p=0.006), diabetes (10% vs 32%), p=0.002) and hyperlipemia (37% vs 79%, p=0.002).

Coronary physiology parameters showed a non-normal distribution, and are expressed as median [IQR] (Table 1). In patients with AMI, FFR was lower than in patients with SCD. In contrast, RFR showed no significant difference. Both CFR and RRR were higher in the AMI group. No significant differences in IMR were found between cohorts.

Importantly, in the AMI group the correlation between RFR and FFR was 0.84 and the overall agreement 82%, with rates of false positive and negative of 15% and 3%, respectively. In SCD the correlation was 0.81 with a lower overall agreement of 69%, due mostly to a higher rate of false positive RFR (28%) (Figure 1).

Table 1. Microcirculatory parameters in non-culprit artery (AMI) and stable coronary disease (SCD) AMI (N=66) Stable (N=67) p value FFR 0.84 [0.76–0.9] 0.84 [0.76–0.9] 0.006 RFR 0.89 [0.82–0.94] 0,9 [0.84–0.94] 0.24 CFR 2.2 [1.7–3.1] 1.8 [1.1–2.6] 0.011 IMR 17 [14–27] 25 [14–38] 0.051 RRR 2.7 [2.17 - 3.9] 2.1 [1.4–3.1] 0.005 Median [IQR].

Figure 1. Correlation between RFR and FFR valueS

Conclusions

RFR shows a good correlation with FFR in AMI. Surprisingly, overall agreement is higher in the non-culprit artery in an acute setting, with a lower percentage of false positive results.

Acknowledgement/Funding

None

6115Influence of microvascular function and coronary flow in the diagnostic precision of resting full-cycle ratio

Introduction

Resting full-cycle ratio (RFR) has been recently described as a non-hyperemic index of coronary stenosis with good concordance with Fractional Flow Reserve (FFR). However, there is no information concerning the influence of microvascular function and coronary flow on RFR results.

Purpose

To determine if the accuracy of this novel parameter might be influenced by changes in microvascular function.

Methods

133 patients admitted in our center between July 2016 and December 2017 underwent coronary physiology study of an angiographically intermediate lesion. 67 subjects presented with AMI and an intermediate lesion in a non-culprit artery, and 66 subjects stable coronary disease. We performed FFR, Coronary Flow Reserve (CFR), Index of Microcirculatory Resistance (IMR) and Resistance Reserve Ratio (RRR) in all of them. We calculated RFR retrospectively from the pressure tracings.

Results

Coronary physiology parameters showed a non-normal distribution and are presented as median [IQR]: FFR 0.86 [0.79–0.92]; CFR 2.05 [1.4–2.95]; IMR 20.5 [14–32.55]; RRR 2.5 [1.85–3.63]; RFR 0.897 [0.83–0.94]. Patients with abnormal CFR displayed lower RFR values although FFR was not markedly affected (Table 1). These findings remained irrespective of the clinical scenario at presentation.

61 patients had a CFR lower than 2. Correlation between RFR and FFR was not significantly different in patients with abnormal CFR than in those with normal CFR (0,73 vs 0,88; p=0,067) (Figure 1); however, overall binary agreement between RFR and FFR was worse in patients with a low CFR (69% vs 83%; p=0,047).

48 patients had a high IMR (>25). Linear correlation between RFR and FFR was similar in patients with high and normal IMR (0,81 vs 0,83; p=0,784); likewise, binary concordance showed no significant difference between both groups (77% vs 75%, p=0,78).

The mean difference between RFR and FFR was 0,025. This was only influenced by CFR: patients with a low CFR had a smaller difference than those with a normal CFR (0,012 vs 0,035; p=0,019).

Physiology parameters by CFR group Normal CFR (≥2) Low CFR (<2) P-value FFR 0.88 [0.82–0.93] 0.84 [0.79–0.92] 0.14 RFR 0.91 [0.88–0.95] 0.86 [0.80–0.92] 0.0009 IMR 16.5 [13–27] 25 [16–45.5] 0.002 RRR 3.6 [2.7–4.9] 1.7 [1.3–2.1] <0.0001 Physiological coronary parameters (Median [IQR]) according to CFR.

Correlation between RFR and FFR by CFR

Conclusion

RFR has good overall correlation and concordance with FFR. However, RFR has a lower diagnostic accuracy in patients with a low CFR.

Acknowledgement/Funding

None

Parainfluenza virus 3 infection after stem cell transplant: relevance to outcome of rapid diagnosis and ribavirin treatment

All 456 recipients of hemopoietic stem cell transplants (SCT) at the Hammersmith Hospital, London, from January 1990 through September 1996 were reviewed for parainfluenza virus (PIV) infections. Of the 24 (5.3%) PIV type 3 (PIV3)-infected patients, 10 had upper respiratory tract infection and all survived, but 8 of 14 with pneumonia died. A same-day immunofluorescence test diagnosed PIV3 infection in 20 (83%) of the 24 cases, but virus culture diagnosed only 10 (42%) of the 24 cases after a mean delay of 12 days. Eighteen PIV3-infected patients first received ribavirin at a median of 3 days after onset of symptoms, but, nevertheless, 2 patients shed PIV3 for 4 months. Six of 10 patients with pneumonia died despite early ribavirin therapy. The cause of death was not established by autopsy; 3 patients had concurrent infections, but in 3, only PIV3 was detected. The value of immunofluorescence testing for early diagnosis and treatment of PIV3 infection after SCT is demonstrated, but the outcome was not altered.

[The practical clinical guidelines of the Sociedad Española de Cardiología on interventional cardiology: coronary angioplasty and other technics]

Interventional cardiology has had an extraordinary expansion in last years. This clinical guideline is a review of the scientific evidence of the techniques in relation to clinical and anatomic findings. The review includes: 1. Coronary arteriography. 2. Coronary balloon angioplasty. 3. Coronary stents. 4. Other techniques: directional atherectomy, rotational atherectomy, transluminal extraction atherectomy, cutting balloon, laser angioplasty and transmyocardial laser and endovascular radiotherapy. 5. Platelet glycoprotein IIb/IIIa inhibitors. 6. New diagnostic techniques: intravascular ultrasound, coronary angioscopy, Doppler and pressure wire. For the recommendations we have used the classification system: class I, IIa, IIb, III like in the guidelines of the American College of Cardiology and the American Heart Association.

Coronary stenting during rescue angioplasty after failed thrombolysis

Compared with primary angioplasty [percutaneous transluminal coronary angioplasty (PTCA)], rescue PTCA is associated with lower angiographic success and higher reocclusion rates, especially after thrombolysis with tissue-type plasminogen activator (tPA). Although stent placement during primary PTCA has been demonstrated to be safe and even to improve the angiographic results achieved by balloon-alone PTCA, there are few data on stent placement during rescue PTCA after failed thrombolysis. This study sought to assess the feasibility and safety of stent implantation during rescue angioplasty in myocardial infarction after failed thrombolysis. The study population consisted of 20 patients with acute myocardial infarction referred for rescue PTCA after failed thrombolysis consecutively treated with coronary stenting. The thrombolytic agent was tPA in 15 patients (75%), streptokinase in 1 (5%), and anisoylated streptokinase plasminogen activator complex (APSAC) in 1 (5%); 3 patients (15%) were included in the INTIME II study (tPA vs. lanoteplase). After stenting, aspirin 200 mg daily plus ticlopidine 250 mg b.i.d. were administered. Thirty stents (1.5+/-1.0 per patient) were implanted. Angiographic success was achieved in 19 patients (95%). Two patients (10%) died, both because of severe bleeding complications. One patient (5%) suffered a reinfarction, but no patients suffered postinfarction angina or needed new target vessel revascularization. Eighteen patients (90%) were discharged alive and free of events. All these patients remained asymptomatic and free of target vessel revascularization at 6-month follow-up. Stent placement during rescue PTCA after failed thrombolysis is feasible and safe and is associated with a good angiographic result and clinical outcome. Bleeding complications seem to be, however, the main limitation of this reperfusion strategy.

[Registry of activities of the Hemodynamics and Interventional Cardiology Section in the year 1996]

The results of the Spanish Registry of Hemodynamic and Interventional Cardiology in 1996 are presented. The Registry collects the activity of 81 centers which constitutes all of the cardiac catheterization laboratories in Spain. The main activity was adult cardiac catheterization in 73 centers and exclusively pediatric cardiac catheterization in 8. A total of 63,961 diagnostic catheterization procedures were performed, which represents a 10.7% increase compared to 1995. This was mainly due to the increase in coronary angiographies. Coronary interventions increased by 21.4%, for a total number of 15,009 procedures. The ratio of coronary interventions per million inhabitants was 375. Success rates of coronary interventions (94%) and complications (2.9%) were similar to those registered in preceding years. In the specific field of revascularization devices, there has been a sustained and spectacular increase in the use of intracoronary stents in the last 3 years. In 1996, coronary stents were employed in 7,104 cases (47.3% of all coronary revascularization procedures) and 8,873 prosthesis were implanted, increasing two-fold the activity in that field when compared to 1995. Stent implantation was elective in 58% cases, and the complication rate was very low (1% subacute closure; 1.8% myocardial infarction and 0.9% mortality). Directional coronary atherectomy decreased by 47% in the last year whereas rotational atherectomy increased by 10% despite a reduction in the number of centers performing this technique. As in previous years, a slight decrease in adult valvuloplasties was noted. Pediatric interventional procedures (607) increased by 30% compared to the 1995 Registry.

Q fever mimicking herpetic encephalitis

We describe a patient with temporal lobe encephalitis associated with primary Coxiella burnetii infection who presented with CT and MRI findings suggestive of herpes simplex encephalitis and an initial improvement during treatment with acyclovir. Q fever should be considered in the differential diagnosis of patients whose manifestations suggest herpes encephalitis.

Selective inhibition of the contractile apparatus. A new approach to modification of infarct size, infarct composition, and infarct geometry during coronary artery occlusion and reperfusion

BACKGROUND

Myocardial reperfusion is associated with calcium overload and cell contracture, mechanisms that may precipitate cell death. In this study, we tested the hypothesis that in vivo inhibition of this contracture could lead to cell preservation in an open-chest large animal model.

METHODS AND RESULTS

Regional myocardium function was measured during a selective intracoronary infusion of 2,3-butanedione monoxime (BDM), a specific inhibitor of actin-myosin coupling, in the control state (10 pigs) and in a protocol of a 51-minute coronary occlusion followed by reperfusion (40 pigs). The effects on coronary artery blood flow in the basal state were also studied (seven pigs). Intramyocardial distribution of the infusate during coronary occlusion, myocardial water content after 30 minutes of reperfusion and area at risk, infarct size, type of histological necrosis, and infarct geometry after 24 hours of reperfusion were assessed. Methods used included electromagnetic flowmeter, radiolabeled microspheres, subendocardial sonomicrometers, fluorescein, triphenyl tetrazolium chloride and Masson's trichrome staining, and computer quantification of infarct edges. In the absence of ischemia, BDM infusion inhibited regional shortening in a dose-dependent manner up to full systolic bulging while producing marked regional increase in coronary blood flow. During early reperfusion, BDM reduced end-diastolic length 76% more than the control infusion (p less than 0.05) and increased systolic bulging by 420% compared with no change in control animals. The ratio of infarct size/area at risk was reduced by 31% with BDM (p less than 0.05), with striking modifications of infarct histology and infarct geometry; specifically, the extent of contraction band necrosis was reduced by 63% from 105.5 +/- 18.2 to 39.2 +/- 13.6 mm2 (p less than 0.02), and more patches of necrosis (6.5 +/- 2.1 versus 1.6 +/- 0.4, p less than 0.05) and higher contour (7.7 +/- 1.2 versus 5.03 +/- 0.2, p less than 0.05) and fractal (12.1 +/- 1.3 versus 7.8 +/- 0.2, p less than 0.05) indexes were found.

CONCLUSIONS

Selective intracoronary infusion of BDM at doses inhibiting regional wall motion decreased infarct size after reperfusion. The effects of BDM on regional function, the reduction in contraction band necrosis at histology, and the peculiar configuration of these infarcts all suggest that inhibition of contracture can interfere with cell-to-cell progression of myocardial necrosis, supporting a role for contracture in reperfusion-induced cell death.

Favorable effects of hyperosmotic reperfusion on myocardial edema and infarct size

Myocardial water content and infarct size were studied in 39 pigs randomly assigned to a nonintervention group, a group with an intracoronary infusion of a control solution, and a group with a hyperosmotic infusion to 450 mosM by the addition of D-mannitol. The intracoronary solutions were selectively infused into the left anterior descending coronary artery just distal to the occlusion site starting 48 min after occlusion. Reperfusion was performed 3 min later and the infusion rate progressively tapered off over the following 33 min. Multiple myocardial fragments were then obtained in nine pigs, from endocardial, mesocardial, and epicardial regions of the ischemic and control myocardium. Water content measured after 48 h of dessication was significantly greater in the reperfused [530 +/- 7 ml/100 (mean +/- SE) g dry wt] compared with control myocardium (374 +/- 3; P less than 0.0001) and similar in reperfused control and isotonic infusion groups (556 +/- 7 and 543 +/- 8 ml/100 g dry wt); it was 491 +/- 11 with intracoronary D-mannitol infusion, representing 35% less increase (P less than 0.001). In the 30 remaining pigs, area at risk and infarct size were measured 24 h later by in vivo fluorescein and in vitro triphenyltetrazolium chloride. Infarct size was similar in control and in the isotonic reperfused hearts, 6.80 +/- 1.05 and 6.22 +/- 0.76% of ventricular weight, and smaller with D-mannitol, 4.46 +/- 0.46 (P less than 0.05). The ratio of infarct size to area at risk was also smaller [0.415 +/- 0.029 vs. 0.543 +/- 0.052 and 0.547 +/- 0.045 (P less than 0.02)].(ABSTRACT TRUNCATED AT 250 WORDS)

Intracoronary infusion of superoxide dismutase and reperfusion injury in the pig heart

The effects of an intracoronary infusion of superoxide dismutase on infarct size were studied in 16 pigs submitted to a 48-min coronary occlusion of the mid left anterior descending coronary artery followed by reperfusion for 24 h. Areas at risk marked with fluorescein and infarct sizes calculated with triphenyl tetrazolium chloride staining 24 h after the occlusion were similar in the five control animals with coronary reperfusion alone, in the five animals with an intracoronary infusion of lactate Ringer initiated 3 min before reperfusion and maintained for 33 min and in the six animals with superoxide dismutase added to the solution of lactate Ringer and infused at a rate of 2500 units/min. The ratios infarct size/area at risk were respectively 0.50 +/- 0.10, 0.65 +/- 0.04 in the three study groups (NS). The extent of intramyocardial hemorrhage, evaluated by morphometric analysis was also similar 0.90 +/- 0.29 x 10(6), 0.70 +/- 0.14 and 1.62 +/- 0.42 red blood cells/mm3 of tissue (NS). The superoxide dismutase infusion, however, resulted in significantly fewer early reperfusion arrhythmias which involved 23 +/- 15 s of each minute electrocardiographic recording in the superoxide dismutase group, compared to 37 +/- 13 s in the lactate Ringer group and 45 +/- 14 s in the control group (p = 0.004). The lack of an effect of intracoronary infusion of superoxide dismutase on infarct size suggests that in this experimental model, extracellular superoxide radicals generated during early reperfusion have no major role on myocardial cell necrosis and microvascular damage. Reperfusion arrhythmias were, however, reduced.

Determinants of hemorrhagic infarcts. Histologic observations from experiments involving coronary occlusion, coronary reperfusion, and reocclusion

Quantification of intramyocardial hemorrhage was performed in 69 pigs submitted to various protocols of coronary artery occlusion and reperfusion. The study groups include 1) permanent occlusion; 2) reperfusion after periods of coronary occlusion of 30, 45, 60, 90, and 120 minutes; 3) reperfusion with diltiazem and with 4) methoxamine after a 60-minute occlusion period; and 5) permanent reocclusion after a 30-minute period of reperfusion. Red blood cell counts were directly assessed by visual examination of histologic slices of myocardium and in a subgroup of animals by counts of red blood cells labeled with 99m-technetium pertechnetate. Hemorrhage occurs in infarcts reperfused after a duration of 45 minutes or more of coronary occlusion and after a period of reperfusion maintained for at least 30 minutes. Red blood cell counts were maximal in the mid portions of transmural sections of the infarcts, with decreasing values toward epicardium and endocardium. Diltiazem decreased total red blood cell counts, whereas methoxamine increased it and also caused subendocardial hemorrhage. The most powerful predictors of the severity of hemorrhage after sustained reperfusion were infarct size and higher blood pressure.

Cell-to-cell interaction: a mechanism to explain wave-front progression of myocardial necrosis

Histological sections performed 24 h after coronary occlusion in eight pigs displayed compact infarcts extending transmurally with well-defined edges; reconstruction and inspection of the area of necrosis showed a geometric distribution of the infarcts with very irregular, interdigitating edges always in continuity with the main mass of necrosis. Reperfusion in 32 pigs after periods of coronary occlusion of 90, 60, 45, and 30 min exponentially reduced infarct size and transmural extension of the infarct but did not modify its geometry. The two-dimensional size, progression, and geometry of the infarcts could be reproduced by a computer model. In the simulated infarcts, each myocardial cell within the area at risk was represented by a pixel. The algorithm included an inner loop, which determined at random at each iteration a status of reversible or irreversible damage to all pixels. The number of iterations could reproduce infarct of various sizes. With the addition of an index of transmural sensitivity to ischemia, progression of the infarct area could also be reproduced. The only possible means of reproducing the geometry of the infarct was to enter into the program a contiguity condition requiring a direct contact between irreversibly damaged pixels. These observations suggest that the physical interaction between cells is an important determinant of progression of necrosis during coronary occlusion.

Influence of tachycardia and arterial hypertension on infarct size in the pig

To investigate the clinically important but controversial question of how hypertension during coronary occlusion affects infarct size 24 pigs underwent 1 h occlusion of the mid left anterior descending coronary artery and 24 h reperfusion and were randomised to one of three treatment groups. In group 1 blood pressure was increased during the occlusion period by an infusion of methoxamine; in group 2 tachycardia was induced by atrial pacing; and in group 3 no intervention was performed. The area at risk and infarct size were quantified by digital planimetry of slices of myocardium previously marked with fluorescein and with triphenyl-tetrazolium. Methoxamine maintained mean aortic blood pressure at 117 (SEM8) mmHg during occlusion, whereas the values were 80(6) mmHg in group 2 and 67(9) mmHg in group 3. Pacing increased heart rate to 146(1) beats.min-1 in group 2; it was 103(5) in group 1 and 99(8) in group 3. The pressure-rate product achieved was similar in groups 1 and 2 and significantly higher than in group 3. The pathological studies showed infarct size to be moderately but significantly larger in group 1 (14[3.5]% of the left ventricle) and similar in groups 2 (10.5[3.9]%) and 3 (10.1[2.2]%). The ratio of infarct size to area at risk was also significantly higher (0.743[0.057]) in group 1 with no differences between group 2 (0.604[0.055]) and group 3 (0.613[0.027]). At similar pressure-rate product, infarct size was thus greater with hypertension but not with pacing alone, showing a deleterious effect of increasing blood pressure in this experimental model with negligible collateral blood flow.

Diltiazem and progression of myocardial ischemic damage during coronary artery occlusion and reperfusion in porcine hearts

This study was designed to investigate whether a cardioprotective intervention could delay the completion of necrosis so that subsequent reperfusion would be more useful. Thirty-six pigs were randomly allocated to treatment with diltiazem (15 micrograms/kg per min) or saline solution and to a 60 or 120 minute coronary occlusion period followed by reperfusion. The treatment was begun 15 minutes before coronary occlusion and terminated 75 minutes after reperfusion. Twenty-four hours after the procedure, the heart was sliced and incubated in triphenyltetrazolium chloride. The infarct area and the maximal transmural area of extension of the infarct were calculated by planimetry. The total number of red blood cells in a transmural section was also counted. In the pigs with a 60 minute coronary occlusion, diltiazem (compared with saline solution) significantly reduced infarct size from 9.7 +/- 1.5% of left ventricular mass to 5.9 +/- 0.6% (p less than 0.05) and the percent transmural extension from 0.72 +/- 0.05 to 0.61 +/- 0.05% (p less than 0.05). Red blood cell extravasation in the infarcted area was reduced from 161,934 +/- 59,905 to 78,525 +/- 46,484 cells/mm3 (p less than 0.05) with diltiazem and the percent transmural extension of the hemorrhagic necrosis from 70 +/- 10 to 36 +/- 15% (p less than 0.05). No such differences were observed in the 120 minute coronary occlusion groups. Mean red blood cell counts and the extent of hemorrhagic necrosis did not correlate with either infarct size or transmural extension.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial reperfusion in the pig heart model: infarct size and duration of coronary occlusion

The effect of coronary artery reperfusion on infarct size was studied in a pig heart model. Forty four open chest pigs underwent occlusion of the mid-left anterior descending artery. Fifteen minutes after occlusion the animals were randomised to one of five groups: reperfusion at 30, 45, 60, or 90 min after occlusion (groups 1-4) or permanent occlusion (group 5). Twenty four hours after coronary occlusion the pigs were killed. The heart was sectioned in slices, which were incubated in triphenyl-tetrazolium. Mean(SEM) infarct sizes calculated by planimetry were 0.46(0.42), 2.85(1.14), 9.74(1.65), 8.93(1.37), and 13.17(1.17)% of left ventricular mass in the five groups. The transmural extension of the infarct was 14.6(11.4), 42.1(12.9), 87.4(6.6), 96.2(3.2), and 100(0)% and a transmurality index used as an estimate of the mean extension of the infarct relative to wall thickness was calculated to be 0.08(0.06), 0.32(0.10), 0.72(0.06), 0.79(0.04), and 0.92(0.02) respectively. Infarct size was similar in groups 3-5, but significantly smaller in groups 1 and 2 (p less than 0.05). Infarct size and the transmurality index correlated exponentially with the duration of the occlusion (r = 0.80, p less than 0.01; and r = 0.95, p less than 0.001 respectively). These results indicate that in the pig heart model submitted to an acute coronary occlusion cell viability may be less than that suggested by previous canine studies. This observation is probably related to a less well developed collateral blood flow in the pig heart and may provide an experimental model that better resembles certain clinical conditions.