A ventricular fibrillation cardiac arrest model with extracorporeal cardiopulmonary resuscitation in rats: 8 minutes arrest time leads to increased myocardial damage but does not increase neuronal damage compared to 6 minutes

Introduction

Extracorporeal cardiopulmonary resuscitation (ECPR) is an emerging strategy in highly selected patients with refractory cardiac arrest (CA). Animal models can help to identify new therapeutic strategies to improve neurological outcome and cardiac function after global ischemia in CA. Aim of the study was to establish a reproducible ECPR rat model of ventricular fibrillation CA (VFCA) that leads to consistent neuronal damage with acceptable long-term survival rates, which can be used for future research.

Materials and methods

Male Sprague Dawley rats were resuscitated with ECPR from 6 min (n = 15) and 8 min (n = 16) VFCA. Animals surviving for 14 days after return of spontaneous resuscitation (ROSC) were compared with sham operated animals (n = 10); neurological outcome was assessed daily until day 14. In the hippocampal cornu ammonis 1 region viable neurons were counted. Microglia and astrocyte reaction was assessed by Iba1 and GFAP immunohistochemistry, and collagen fibers in the myocardium were detected in Azan staining. QuPath was applied for quantification.

Results

Of the 15 rats included in the 6 min CA group, all achieved ROSC (100%) and 10 (67%) survived to 14 days; in the 8 min CA group, 15 (94%) achieved ROSC and 5 (31%) reached the endpoint. All sham animals (n = 10) survived 2 weeks. The quantity of viable neurons was significantly decreased, while the area displaying Iba1 and GFAP positive pixels was significantly increased in the hippocampus across both groups that experienced CA. Interestingly, there was no difference between the two CA groups regarding these changes. The myocardium in the 8 min CA group exhibited significantly more collagen fibers compared to the sham animals, without differences between 6- and 8-min CA groups. However, this significant increase was not observed in the 6 min CA group.

Conclusion

Our findings indicate a uniform occurrence of neuronal damage in the hippocampus across both CA groups. However, there was a decrease in survival following an 8-min CA. Consequently, a 6-min duration of CA resulted in predictable neurological damage without significant cardiac damage and ensured adequate survival rates up to 14 days. This appears to offer a reliable model for investigating neuroprotective therapies.

Psychocardiological assessment in the acute phase of the takotsubo syndrome : Somatic and depressive disorders, resilience and illness perception

Objective

To analyze the psychocardiological profile and the clinical characteristics in the acute phase of takotsubo syndrome (TTS).

Methods

Prospective multicenter cohort study of TTS patients evaluating the clinical characteristics as well as the prevalence of somatic, depressive, panic, stress and anxiety disorders. Assessment of illness perception and resilience in the acute phase of the syndrome.

Results

All 27 evaluated TTS patients were female with a mean age of 68 years (±11.4 years). The apical type of TTS was found in 60% of patients, followed by the combined type of TTS in 30% of patients. Main clinical symptom leading to hospital admission was chest pain in nearly 80% of patients. An ST-segment elevation mimicking acute myocardial infarction was found in 44% of patients and T wave inversion in 26% of patients. An endogenous (emotional) stress event was found in 17 patients (63.0%), an exogenous (physical) stress event in 5 patients (18.5%) and a combined stress event in 2 patients (7.4%). In 11.1% of patients (n = 3) no stress event could be found. Moderate to high levels of illness threatening were found in 48% of patients and low to moderate resilience scores were found in 40% of patients. Somatic disorders were found in half of the patients (56%) followed by depressive disorders in 26% of patients.

Conclusion

Moderate to low resilience scores and moderate to high levels of illness threatening can be seen in the acute phase of TTS, reflecting the severity of the experience as an adverse life event. Patients suffering from TTS present in the acute phase with a high prevalence of somatic disorders and relatively high prevalence of depressive disorders.

Motor Cortex and Hippocampus Display Decreased Heme Oxygenase Activity 2 Weeks After Ventricular Fibrillation Cardiac Arrest in Rats

Heme oxygenase (HO) and biliverdin reductase (BVR) activities are important for neuronal function and redox homeostasis. Resuscitation from cardiac arrest (CA) frequently results in neuronal injury and delayed neurodegeneration that typically affect vulnerable brain regions, primarily hippocampus (Hc) and motor cortex (mC), but occasionally also striatum and cerebellum. We questioned whether these delayed effects are associated with changes of the HO/BVR system. We therefore analyzed the activities of HO and BVR in the brain regions Hc, mC, striatum and cerebellum of rats subjected to ventricular fibrillation CA (6 min or 8 min) after 2 weeks following resuscitation, or sham operation. From all investigated regions, only Hc and mC showed significantly decreased HO activities, while BVR activity was not affected. In order to find an explanation for the changed HO activity, we analyzed protein abundance and mRNA expression levels of HO-1, the inducible, and HO-2, the constitutively expressed isoform, in the affected regions. In both regions we found a tendency for a decreased immunoreactivity of HO-2 using immunoblots and immunohistochemistry. Additionally, we investigated the histological appearance and the expression of markers indicative for activation of microglia [tumor necrosis factor receptor type I (TNFR1) mRNA and immunoreactivity for ionized calcium-binding adapter molecule 1 (Iba1])], and activation of astrocytes [immunoreactivity for glial fibrillary acidic protein (GFAP)] in Hc and mC. Morphological changes were detected only in Hc displaying loss of neurons in the cornu ammonis 1 (CA1) region, which was most pronounced in the 8 min CA group. In this region also markers indicating inflammation and activation of pro-death pathways (expression of HO-1 and TNFR1 mRNA, as well as Iba1 and GFAP immunoreactivity) were upregulated. Since HO products are relevant for maintaining neuronal function, our data suggest that neurodegenerative processes following CA may be associated with a decreased capacity to convert heme into HO products in particularly vulnerable brain regions.

P5676Implementing a syncope pathway

Background

Syncope is a common presenting symptom in emergency departments (0.8–2.4%) and is associated with high health care costs. In up to 40% of cases, etiology remains unidentified after initial evaluation.

Purpose

To assess the increase in diagnostic yield and the time to diagnosis by implementing a structured pathway in syncope evaluation according ESC- Guidelines in a secondary hospital.

Methods

In the study, we compared 2 groups of patients with T-LOC. We evaluated the diagnostic yield and the time to diagnosis. The first group comprised all patients with T-LOC referred to the emergency department (ED) of the hospital from January to March 2016. The work-up was done according to existing clinical practice.

After implementation of a structured pathway in syncope evaluation according to ESC-Guidelines, we reevaluated the diagnostic yield and the time to diagnosis in all patients referred to ED with T-LOC from July to September 2017. The implementation consisted of an initial evaluation (careful history taking with a checklist, physical examination, ECG, orthostatic challenge test carried out by nurses), risk assessment and instructing the medical staff.

Results

There were 169 vs. 85 patients presenting with suspected T-LOC in the ED. 130 (77%) vs. 65 (76.5%) were classified as having a syncope. The diagnostic yield in the syncope patients was 60% vs. 80% (p=0.013). The rate of correct diagnosis within 14 days increased from 55 to 80%.

Conclusion

By implementing a structured pathway and educating the staff, we succeeded in increasing diagnostic yield from 60 to 80%. This could be achieved in a reduced referral to diagnosis time.

Reduction of Serious Adverse Events Demanding Study Exclusion in Model Development: Extracorporeal Life Support Resuscitation of Ventricular Fibrillation Cardiac Arrest in Rats

Extracorporeal life support is a promising concept for selected patients in refractory cardiogenic shock and for advanced life support of persistent ventricular fibrillation cardiac arrest. Animal models of ventricular fibrillation cardiac arrest could help to investigate new treatment strategies for successful resuscitation. Associated procedural pitfalls in establishing a rat model of extracorporeal life support resuscitation need to be replaced, refined, reduced, and reported.Anesthetized male Sprague-Dawley rats (350-600 g) (n = 126) underwent cardiac arrest induced with a pacing catheter placed into the right ventricle via a jugular cannula. Rats were resuscitated with extracorporeal life support, mechanical ventilation, defibrillation, and medication. Catheter and cannula explantation was performed if restoration of spontaneous circulation was achieved. All observed serious adverse events (SAEs) occurring in each of the experimental phases were analyzed.Restoration of spontaneous circulation could be achieved in 68 of 126 rats (54%); SAEs were observed in 76 (60%) experiments. Experimental procedures related SAEs were 62 (82%) and avoidable human errors were 14 (18%). The most common serious adverse events were caused by insertion or explantation of the venous bypass cannula and resulted in lethal bleeding, cannula dislocation, or air embolism.Establishing an extracorporeal life support model in rats has confronted us with technical challenges. Even advancements in small animal critical care management over the years delivered by an experienced team and technical modifications were not able to totally avoid such serious adverse events. Replacement, refinement, and reduction reports of serious adverse events demanding study exclusions to avoid animal resources are missing and are presented hereby.

Reduced long-term memory in a rat model of 8 minutes ventricular fibrillation cardiac arrest: a pilot trial

Background

Evaluating beneficial effects of potential protective therapies following cardiac arrest in rodent models could be enhanced by exploring behavior and cognitive functions. The Morris Water Maze is a well-known cognitive paradigm to test spatial learning and memory.

Results

Behavioral testing with the Morris Water Maze in Sprague–Dawley rats (300 ± 25 g) resuscitated after 8 min of ventricular fibrillation cardiac arrest was carried out 5 and 12 weeks after cardiac arrest (CA) and compared to results of naïve rats (Control).

At 5 weeks, within each group latency time to reach the hidden platform (reflecting spatial learning) decreased equally from day 1 to 4 (CA: 105.6 ± 8.2 vs. 8.9 ± 1.2 s, p < 0.001; Control: 75.5 ± 13.2 vs. 17.1 ± 4.5, p < 0.001) with no differences between groups (p = 0.138). In the probe trial 24 h after the last trial, time spent in the target sector (reflecting memory recall) within each group was significantly longer (CA: 25 ± 1.3; Control: 24.7 ± 2.5 s) than in each of the three other sectors (CA: 7.7 ± 0.7, 14.3 ± 2.5, 8.4 ± 0.8 and Control: 7.8 ± 1.2, 11.7 ± 1.5, 10.3 ± 1.6 s) but with no significantly differences between groups. Seven days later (reflecting memory retention), control group animals remained significantly longer in the target sector compared to every other sector, whereas the cardiac arrest group animals did not. Even 12 weeks after cardiac arrest, the single p values showed that the control animals displayed a trend to perform better than the resuscitated animals.

Conclusions

Memory recall was impaired early after 8 min of ventricular fibrillation cardiac arrest and might be a more valuable tool for cognitive testing than learning recall after global ischemia due to cardiac arrest.

Development and investigation of a long-range time-of-flight and color imaging system

Time-of-flight (Tof) imaging based on the photonic mixer device (PMD) or similar ToF imaging solutions has been limited to short distances in the past, due to limited lighting devices and low sensitivity of ToF imaging chips. Long-range distance measurements are typically the domain of laser scanning systems. In this paper, PMD based medium- and long-range lighting devices working together with a 2-D/3-D camera are presented and several measurement results are discussed. The proposed imaging systems suffer from two systematic limitations in addition to problems due to wind and insufficient lighting: a low lateral resolution of the depth imaging chip and ambiguities in the distance measurements. In order to provide a robust and flexible system, we introduce algorithms to obtain unambiguous depth values (phase unwrapping) and to perform a joint motion compensation and super-resolution. Several experiments were conducted in order to evaluate the components of the multimodal imaging system.

Stress-induced cardiomyopathy (Tako-Tsubo syndrome) in Austria

BACKGROUND

Tako-Tsubo syndrome (TS) is a still rarely diagnosed clinical syndrome, which is characterized by acute onset of chest pain, transient cardiac dysfunction with (frequently) reversible wall motion abnormalities (WMAs), but with no relevant obstructive coronary artery disease.

METHODS AND RESULTS

Among 179 consecutive patients with proven diagnosis of TS that were retrospectively analysed in this multicentre registry, women represented the majority of patients (94%) while only 11 men (6%) developed TS. Mean age was 69.1±11.5 years (range 35-88 years). Cardinal symptoms of TS, which led to admission, were acute chest pain (82%) and dyspnoea (32%), respectively. All patients demonstrated typical WMAs, whereby four different types of WMAs could be defined: (1) a more common apical type of TS (n=89; 50%); (2) a combined apical and midventricular form of TS (n=23; 13%); (3) the midventricular TS (n=6; 3%); and (4) an unusual type of basal WMAs of the left ventricle (n=3). Only in 101 patients (57%), a clear causative trigger for onset of symptoms could be identified. In-hospital cardiovascular complications occurred in 25 patients (14%) and consisted of cardiac arrhythmias in 10 patients (40%), cardiogenic shock in six patients (24%), cardiac decompensation in eight patients (32%) and cardiovascular death in one patient, respectively. Echocardiographic control of left ventricular function after the initial measurement was available in almost 70% of the patients: complete recovery of WMAs was found in 73 patients (58.87%); 49 patients (39.52%) showed persistent WMAs. Recurrences of TS were only seen in four patients. During the follow-up period, 13 patients died: three of cardiovascular causes and 10 of non-cardiac causes. In-hospital mortality was 0.6%, 30-day mortality was 1.3% and 2-year mortality was 6.7%.

CONCLUSIONS

This study represents to date the largest series of patients suffering from TS in Austria and worldwide. Similar to others, in our series the prevalence of TS was significantly higher in women than in men, while in contrast to other studies, the apical type of TS was detected most frequently. The similar clinical presentation of TS patients to the clinical picture of acute myocardial infarction demonstrates the importance of immediate coronary angiography for adequate differential diagnosis of TS. TS is not necessarily a benign disease due to cardiovascular complications as well as persistent WMAs with delayed recovery.

Surface vs. aortic flush cooling during cardiac arrest in pigs

BACKGROUND

To investigate the feasibility and efficacy of earlier induction of hypothermia already during the 'no-flow' period of cardiac arrest with non-invasive surface cooling or invasive aortic flush cooling.

METHODS

This was a prospective randomized experimental study that included 14 pigs, Large White breed (30-38 kg), with ventricular fibrillation cardiac arrest plus blanket surface and an invasive cold saline flush cooling. The endpoint was a decline in brain temperature (T(br)) at 35 min after cardiac arrest.

RESULTS

With surface cooling, T(br) decreased from 38.7+/-0.2 degrees C to 37.4+/-0.8 degrees C (P=0.02) and with invasive cooling T(br) decreased from 38.8+/-0.13 degrees C to 19.0+/-2.8 degrees C within 216+/-23 s (P=0.02) and increased back to 33.0+/-0.6 degrees C at 35 min of cardiac arrest (P=0.02 vs. T(br) at 15 min, P=0.002 vs. T(br) at 35 min in the surface cooling groups).

CONCLUSION

Invasive cooling by aortic flush with cold saline rapidly induces deep cerebral hypothermia, whereas non-invasive surface cooling only marginally decreases brain temperature.

Emergency preservation and resuscitation improve survival after 15 minutes of normovolemic cardiac arrest in pigs*

OBJECTIVE

Outcome after prolonged normovolemic cardiac arrest is poor, and new resuscitation strategies have to be found. We hypothesized that the induction of deep hypothermia for emergency preservation and resuscitation (EPR) during prolonged cardiac arrest, before the start of reperfusion, will mitigate the deleterious cascades leading to neuronal death and will thus improve outcome.

DESIGN

Prospective experimental study.

SETTING

University research laboratory.

SUBJECTS

Thirteen pigs, Large White breed (27-37 kg).

INTERVENTIONS

After 15 mins of ventricular fibrillation, pigs were subjected to 1) EPR (n = 6), 20 mins of hypothermic stasis induced with a cold saline aortic flush; or 2) 20 mins of conventional resuscitation (n = 7). Then cardiopulmonary bypass was initiated in both groups, followed by defibrillation. Controlled ventilation and mild hypothermia were continued for 20 hrs; survival was for 9 days. For neurologic evaluation, neurologic deficit score (100% = brain dead, 0-10% = normal), overall performance category (1 = normal, 5 = dead or brain dead), and brain histologic damage score were used.

MEASUREMENTS AND MAIN RESULTS

In the EPR group, brain temperature decreased from 38.5 degrees C +/- 0.2 degrees C to 16.7 degrees C +/- 2.5 degrees C within 235 +/- 27 secs. Five animals achieved restoration of spontaneous circulation and survived to 9 days: two pigs with overall performance category 2 and three pigs with overall performance category 3. Their neurologic deficit score was 45% (interquartile range 35, 50) and histologic damage score was 142 (interquartile range 109, 159). In the control group, four pigs achieved restoration of spontaneous circulation: one survived to 9 days with overall performance category 3, neurologic deficit score 45%, and histologic damage score 226 (restoration of spontaneous circulation, p = .6; survival, p = .03; overall performance category, p = .02).

CONCLUSIONS

EPR is feasible in an experimental pig model and improves survival after prolonged cardiac arrest in pigs. Further experimental studies are needed before this concept can be brought into clinical practice.

External cardiac defibrillation during wet-surface cooling in pigs

OBJECTIVE

During surface cooling with ice-cold water, safety and effectiveness of transthoracic defibrillation was assessed.

METHODS

In a pig ventricular fibrillation cardiac arrest model, once (n = 6), defibrillation was done first in a dry and then in a wet condition using the ThermoSuit System (Life Recovery Systems, HD, LLC, Kinnelon, NJ), which circulates a thin layer of ice-cold water (approximately 4 degrees C) over the skin surface. Another time (n = 6), defibrillation was done first in a wet and then in a dry condition. Success of defibrillation was defined as restoration of spontaneous circulation, and the current and voltage of the defibrillation signal was measured.

RESULTS

There was a tendency toward less number of shocks needed for achieving restoration of spontaneous circulation in the wet condition as compared with the number of shocks needed in the dry condition. The energy delivered in both dry and wet conditions was 144 +/- 3 J.

DISCUSSION

Transthoracic defibrillation is safe and effective in a wet condition after cooling with ice-cold water.

A large Eustachian valve is a confounder of contrast but not of color Doppler transesophageal echocardiography in detecting a right-to-left shunt across a patent foramen ovale

BACKGROUND

Transesophageal contrast echocardiography (cTEE) is considered to be the method of choice for diagnosing patent foramen ovale (PFO), but its diagnostic accuracy compared with color Doppler guided TEE in the presence of an Eustachian valve (EV) has not been evaluated. The main aim of this study was to assess the diagnostic accuracy for PFO diagnosis of color Doppler TEE at low pulse repetition frequency.

METHODS

We ascertained the presence of PFO and EV using cTEE and transthoracic contrast echocardiography (cTTE) in 292 consecutive patients (age 42+/-12 years) with cryptogenic stroke. A diagnosis of PFO was based on the observation of right-to-left shunting of contrast bubbles or by color Doppler with pulse repetition frequency of 20-30 cm/s. An EV with a diameter of >1.5 cm in the bicaval view was considered large.

RESULTS

Overall 204 patients (70%) had evidence of a right-to-left shunt by either contrast echo method. Shunting was demonstrated more frequently by color Doppler than by cTEE, either spontaneously (133 vs. 92; p=0.01) or during provocative maneuvers (166 vs. 184; p=0.01). The sensitivity of color Doppler was significantly higher than that of cTEE (90% vs. 81%; p=0.01). A large EV was found in 37 patients, 31 (84%) of whom had a PFO. The presence of a large EV did not significantly influence the sensitivity of color Doppler for detecting shunting through a PFO, but the sensitivity of cTTE and cTEE was significantly reduced (from 88% to 42%, p<0.001).

CONCLUSIONS

Color Doppler TEE is more accurate than traditional cTEE for PFO diagnosis and is not negatively influenced by the presence of an EV, provided that a low pulse repetition frequency is used.

Secondary prevention after cryptogenic cerebrovascular events in patients with patent foramen ovale

BACKGROUND

Patients with patent foramen ovale and cryptogenic stroke are at risk of recurrence, but there are few data on strategies to prevent this.

METHODS

We studied 280 consecutive patients with cryptogenic cerebrovascular events and a patent foramen ovale examined by multiplane transesophageal echocardiography. Patients received platelet inhibitors (n = 66) or anticoagulation (n = 47) or underwent device closure (n = 167). During the mean follow-up of 2.6 years, we compared the frequency of recurrent events, death and severe treatment complications.

RESULTS

A total of 33 (12%) patients had a recurrent cerebrovascular event. The annual recurrence rates were 13% in patients treated with platelet inhibitors, 5.6% in those on oral anticoagulation, and 0.6% in those after device closure. Independent predictors of recurrent cerebrovascular events were a patent foramen ovale larger than 4 mm (hazard ratio 3.8, 95% CI 1.2-11.2; p = 0.017) or previous strokes (hazard ratio 4.3, 95% CI 2.0-9.2; p < 0.001). Interventional closure of the patent foramen ovale decreased the risk of a recurrent event compared with oral anticoagulation (hazard ratio 0.06, 95% CI 0.12-0.29; p < 0.001), whereas antiplatelet therapy showed a trend to an increased risk (hazard ratio 2.3; 95% CI 0.9-5.5; p = 0.055). Major side effects occurred in 7 anticoagulated patients and in 13 patients after device closure. There were two non-vascular deaths and one fatal hemorrhagic stroke.

CONCLUSIONS

Patients with a large patent foramen ovale and a cryptogenic cerebrovascular event had a substantial risk of recurrence even with medical treatment. Risk of recurrence was lower after device closure of the patent foramen ovale.

Persisting eustachian valve in adults: relation to patent foramen ovale and cerebrovascular events

BACKGROUND

The eustachian valve (EV) (valvula venae cavae inferioris) is a remnant of the embryonic right valve of the sinus venosus. Embryologically, the EV directs oxygenated blood from the inferior vena cava across the patent foramen ovale (PFO) into the systemic circulation. Transthoracic echocardiography shows the EV in the majority of newborns, but the prevalence of EV in adults studied with transesophageal echocardiography is unknown. We studied whether the presence of an EV is associated with PFO or with cryptogenic stroke.

METHODS

The frequency and size of the EV was studied in 211 consecutive patients undergoing transesophageal echocardiography after a cryptogenic stroke and in 95 consecutive patients without cerebrovascular events. In all 306 patients, the presence of a PFO was studied with 2-dimensional transesophageal echocardiographic, color Doppler, and contrast echocardiographic studies.

RESULTS

An EV was seen in 174 of 306 patients overall (57%). The mean size was 1.0 +/- 0.4 cm (range: 0.5-2.0); 70% of patients with an EV had a PFO (Cohen's kappa = 0.75; P <.001). This relationship was not significantly influenced by a cryptogenic stroke. The prevalence of PFO was 30% in the control group and 61% for those with presumed paradoxical embolism (P <.001). Thus, an EV was more common for patients with presumed paradoxical embolism than in control patients (143 of 211 68% vs 31 of 95 33%, respectively, P <.001). There was no significant difference in the size of the EV between the 2 groups (1.1 vs 1.0 cm; P =.24).

CONCLUSION

A persisting EV is a frequent finding in patients with a PFO. By directing the blood from the inferior cava to the interatrial septum, a persisting EV may prevent spontaneous closure of PFO after birth and may, therefore, indirectly predispose to paradoxical embolism.

Transesophageal echocardiography for quantifying size of patent foramen ovale in patients with cryptogenic cerebrovascular events

BACKGROUND AND PURPOSE

Patent foramen ovale (PFO) is a risk factor for paradoxical embolism, and severe shunting and wide opening of PFO are risk factors for severe and recurrent cerebrovascular events. Neither contrast echocardiography nor 2-dimensional (2D) measurement of PFO size have been validated or compared with invasive balloon sizing.

METHODS

We performed transesophageal echocardiography (TEE) in 100 patients with cryptogenic stroke and catheter closure of PFO. The amount of contrast shunting through the PFO during cubital and femoral contrast delivery and the PFO size measured by 2D TEE were compared with balloon sizing.

RESULTS

There was a significant correlation (r(2)=0.8; P<0.0001) between 2D TEE measurement and invasive balloon sizing. Mean balloon-sized PFO diameter was significantly larger than mean PFO diameter measured by 2D TEE (8.3+/-2.6 versus 5.2+/-1.7 mm). Semiquantitative contrast TEE correlated with PFO size (r(2)=0.7; P<0.0001) only if the contrast agent was administered through a femoral vein. Correlation was poor when the contrast agent was administered via a cubital vein.

CONCLUSIONS

We conclude that 2D TEE measurement of a PFO size is more accurate than the traditionally used contrast technique.

The association between the diameter of a patent foramen ovale and the risk of embolic cerebrovascular events

PURPOSE

We sought to determine whether the size of a patent foramen ovale affected the risk of embolic cerebrovascular events of unknown origin.

PATIENTS AND METHODS

We ascertained the presence and measured the size of patent foramen ovale using multiplane transesophageal echocardiography in 121 consecutive patients younger than 60 years who had transient ischemic attacks or ischemic strokes and in 123 control subjects. None of the patients had left heart, aortic, or carotid sources of embolism, or echocardiographic signs of elevated left or right atrial pressure. We used multivariate logistic regression to determine whether the size of the patent foramen ovale was an independent risk factor for cerebrovascular events.

RESULTS

The mean (+/- SD) diameter of a patent foramen ovale was significantly larger in patients (4 +/- 2 mm) than in control subjects (2 +/- 1 mm, P <0.0001). A patent foramen ovale greater than 4 mm was associated with an increased risk of transient ischemic attacks [odds ratio (OR) = 3.4; 95% confidence interval (CI), 1.0 to 11, P = 0.04], ischemic strokes (OR = 12; 95% CI, 3.3 to 44, P = 0.0001), and, especially, having evidence of two or more strokes (OR = 27; 95% CI, 4.7 to 160, P = 0.0002).

CONCLUSION

The diameter of a patent foramen ovale is an independent risk factor for ischemic events, especially recurrent strokes.

[Practical assessment using transmitral Doppler echocardiography for the evaluation of left ventricular filling pressure in patients with systolic ventricular dysfunction]

Transmitral flow velocity profiles by Doppler echocardiography are strongly related to left ventricular diastolic properties. The aim of this study was to address the assessment of left ventricular filling pressures by transmitral flow velocity curves in patients with impaired systolic function. 90 patients (23 female, 67 men, age 60.0 +/- 9,9 a) with an ejection fraction < or = 45% either due to coronary artery disease (n = 67) or dilated cardiomyopathy (n = 23) were investigated by Doppler echocardiography prior to left heart catheterization. Early diastolic deceleration time (DT) and ratio of early to late diastolic peak velocities (VE/VA) were measured. Both, DT and VE/VA showed a significant correlation to left ventricular enddiastolic pressures (r = -0.79 respectively r = 0.73, p < 0.001 for all). According to DT three different transmitral flow patterns were identified. All patients with restrictive filling patterns (DT < 160) had elevated left ventricular filling pressures, whereas impaired relaxation (DT > 210) was a strong predictor of normal filling pressures. In patients with pseudonormal transmitral flow patterns (DT 160 to 210) filling pressures could not be predicted. Furthermore DT was strongly related to clinical signs of left heart failure. Doppler echocardiography gives useful additional information on left ventricular filling pressures in patients with systolic dysfunction.

[The Doppler echocardiographic assessment of left ventricular diastolic function in coronary heart disease]

BACKGROUND AND OBJECTIVE

Changes in left ventricular (LV) diastolic function lead to characteristic changes in the transmitral flow profile as determined by Doppler echocardiography (DEC). Although DEC cannot provide direct quantitative measurement of LV filling pressures and is influenced by several factors, transmitral flow correlates well with LV haemodynamics. In this prospective study the results of transthoracic DEC were compared with haemodynamic parameters in patients with coronary heart disease (CHD) and their clinical value assessed.

PATIENTS AND METHODS

254 consecutive patients with CHD (67 women, 187 men, aged 62.5 +/- 8.5 years) underwent transthoracic DEC. The ratio of early to late diastolic velocity (VE/VA) and early diastolic deceleration time (DT) of the transmitral flow were measured as an indication of diastolic LV function.

RESULTS

Patients with reduced LV compliance and increased filling pressure (LV end-diastolic pressure [LVEDP] > 15 mm hg) had a restrictive transmitral flow profile with a significantly higher than normal VE/VA and a shorter DT (1.35 +/- 0.84 vs. 0.86 +/- 0.26, P < 0.001; and 158 +/- 45 vs. 213 +/- 35, P < 0.001, respectively). VE/VA and DT also significantly correlated with LVEDP (r = 0.65, P < 0.001 and r = -0.60, P < 0.001 respectively). Sensitivity and specificity of an LVEDP of > 15 mm Hg were 67% and 84%, respectively, for a VE/VA of more than 1, and 65% and 91% for a DT of less than 170. The combination of the two parameters increased specificity to 97%.

CONCLUSION

Determining the transmitral flow profile makes it possible noninvasively to obtain an indication of LV end-diastolic function. Patients with severe diastolic dysfunction and increased filling pressures are recognized with a high degree of specificity.

[Preoperative diagnosis of a patent foramen ovale: rational use of transthoracic and transesophageal contrast echocardiography]

BACKGROUND

The detection or ruling out of a patent foramen ovale (PFO) can be determined noninvasively by contrast echocardiography (CE). The transesophageal technique is superior to the transthoracic technique regarding sensitivity, whereas the specificity of both methods is equally high. This prospective study shows the rational use of transesophageal CE for the detection of a PFO, in patients without cardiovascular disorders.

METHODS

165 patients (92 female, 73 male, age 48 +/- 18 years) with planned neuro-surgery in a sitting position, underwent CE to rule out a PFO. If the CE was positive, an alternative position was selected in order to avoid a paradoxical air embolism.

RESULTS

Initially, a transthoracic CE was performed in all patients resulting in 21 patients (13%) being positive and 39 patients (24%) being negative by sufficient image quality. A transesophageal CE was performed in 96 of the remaining 105 patients (63%). Here, further 25 patients showed a positive CE in the sense of a PFO. The combined use of transthoracic and transesophageal CE revealed a PFO in 46 of 165 patients (28%).

CONCLUSION

The use of both, transthoracic and transesophageal CE is an efficient approach to the preoperative detection of a PFO in the sense of quality and economics. Depending upon the image quality, the use of a transesophageal examination could be avoided in one third of the cases.

Simultaneous bilateral contrast transcranial doppler monitoring in patients with intracardiac and intrapulmonary shunts

The prevalence of a right-to-left intracardiac shunt, demonstrated by echocardiography and transcranial Doppler sonography has been shown to be higher in stroke patients than in normal controls. The aim of this study was to assess the sensitivity and specificity of contrast transcranial Doppler sonography in comparison to transesophageal echocardiography in the detection and differentiation of intracardiac and intrapulmonary shunts and to correlate the transcranial Doppler findings with clinical outcome and morphological findings. Forty five consecutive stroke patients with suspected paradoxical embolism were entered into the study. In all 25 patients with middle cerebral artery stroke of the left (56%) or right (44%) territory and echocardiographic demonstrated patent foramen ovale (80%) or intrapulmonary shunt (20%), simultaneous bilateral transcranial Doppler sonography of the middle cerebral arteries was performed after contrast medium injection during rest and valsalva straining under standardized and optimized conditions. Overall sensitivity for the detection of a right-to-left shunt by contrast transcranial Doppler sonography was 97% and overall specificity was 70%. Bilateral appearance of microbubbles, microbubble count and time delay of microbubble appearance significantly increased after valsalva straining. In patients with intracardiac shunts, a significantly higher microbubble count (32 vs. 13 in patients with an intrapulmonary shunt) and a shorter time interval of microbubble appearance (11 vs. 14 s in patients with intrapulmonary shunts) was observed. There was no correlation between the side and numerical distribution of microbubble count and the location and severity of the current clinical symptoms, as well as between microbubble count and presence and hemispherical distribution of brain infarcts. Transcranial Doppler sonography is a highly sensitive method for the detection of right-to-left shunts, whether of cardiac or pulmonary location. However. no correlation was found between the side and number of microbubbles counted and the clinical symptomatology.

[Quantitative determination of left ventricular myocardial perfusion with electron beam computerized tomography]

Myocardial perfusion is one of the most important functional parameters of the heart. Presently various indirect methods are used to determine coronary blood flow or myocardial perfusion as inertgas-, thermodilution-, Doppler catheter- and radiopharmacological techniques. Electron-beam-computed-tomographical technology is able to perform CT data acquisition with a very short exposure time of 50 ms. Using this method it is not only possible to determine left ventricular volumes but also to measure myocardial perfusion in ml/100 g/min. The measurement of the left myocardial perfusion is performed using the short axis view. This position is obtained by moving the table 25 degrees to the patient's right and 15 degrees caudally. To determine the position of the left ventricle, a localization scan is obtained in multi-slice-mode using all for target-rings, thus obtaining 8 tomographic levels over 68 mm (each tomographic level having a slice thickness of 7 mm, with an interslice gap of 4 mm between each two adjacent tomographic levels). In this short axis position, using the multi slice flow mode with 3 target-rings and after administration of 50 ml of contrast medium intravenously with a flow of 3 ml/s, 6 tomographic levels are imaged. Each tomographic level is obtained 13 times at 80% of the R-R-interval at each 2 or 3 heart beat (ECG-gated). The left ventricular myocardial contrast enhancement is measured by drawing manually the outline of the left ventricular myocardium using time-density-software of the Imatron workstation. For calculation of the myocardial perfusion the so-called "slope method" is used and the results are expressed as the maximum slope of enhancement of the myocardium divided by the difference of the precontrast and peak CT-value in the left ventricle. The global myocardial perfusion is calculated as a mean of all evaluated tomographic levels. In this study left ventricular volumes as enddiastolic volume endsystolic volume and stroke volume were measured and ejection fraction and cardiac output calculated. The measurements were performed in the log axis view. This view is obtained by moving the table 15 degrees to the patients left in a horizontal position. In this long axis position 6 tomographic levels are imaged using the multi-slice-cine-mode with 3 target-rings after administration of 50 ml of contrast medium intravenously with a flow of 3 ml/s. Each tomographic level is obtained 13 times starting at 0% of the R-R-interval (ECG-triggering). The exposure time is 50 ms with an interscan time delay of 8 ms. In 9 studied patients of whom one had 3 significant coronary artery stenotic lesions (> 50%), 2 patients had each 2 non significant stenotic lesions (< 50%) and 6 revealed nearly normal coronary angiograms. The mean global myocardial perfusion was 70 ml/100 g/min (min.32 and max. 116 ml/100 g/min). This mean value of 70 ml/100 g/min is reflecting 5% of the cardiac output supposing that the mean heart weight of these patients was 300 g. In this study the mean of the left ventricular muscle mass determined by the use of EBCT was 130 g. A comparative evaluation of coronary angiographic findings in these patients with the measured myocardial perfusion values revealed, that is not sufficient to look only at the absolute values of the measured myocardial perfusion. Furthermore it seems to be necessary to interpret these perfusion values with respect to the calculated cardiac output. Additional studies of well defined patients groups are necessary to determine normal values of myocardial perfusion at rest in patients with and without coronary artery disease. This seems to be important as comparative analysis of myocardial scintigraphic and EBCT-studies is difficult because of methodical inherent differences. The results of this study suggest that despite the presence of some beam hardening artifacts it is possible to measure myocardial perfusion using EBCT in patients with suspected coronary artery disease in the

Donor heart quality control. Analysis of echocardiographic (EC) findings and patient outcome

In a retrospective analysis, 149 echocardiographic (EC) evaluations were compared with conventional clinical parameters for donor heart selection. Of these cases, 12% were found with severe impairment of ventricular wall motion or with morphological abnormalities. Nearly half of the echocardiographically diagnosed pathological findings in donor hearts were not detected by conventional standards for heart screening. Analysis of EC-screened donor heart outcome showed a primary graft nonfunction rate of 3.1%. We suggest EC as an additional screening instrument for further dynamic and morphological information about donor heart condition. Potential donors can be saved for transplantation and severe complications can be avoided by detecting occult cardiac dysfunction. Early detection of cardiac dysfunction may have an impact on donor therapy and can avoid unnecessary and expensive transportation of the surgical team to the harvest site.

[Doppler echocardiography in chronic right ventricular pressure load]

Doppler-echocardiography (DEC) was performed before cardiac catheterization in 61 consecutive patients (25 women, 36 men; aged 59 +/- 10.6 years) with pulmonary hypertension. Chronic obstructive lung disease was its cause in 32, mitral valve disease in 16 and dilated cardiomyopathy in 13 patients. The subcostal approach was possible in all patients and a semiquantitative assessment into three degrees of severity determined from right ventricular wall thickness and size, as well as the diameter of the inferior vena cava. The severity grade was closely correlated with the level of pulmonary hypertension. In the absence of all signs of increased right ventricular load (grade 0) the mean pulmonary arterial pressure was 18.7 +/- 6.2 mm Hg, in grade I it was 15 and 22 mm Hg (only two patients), in grade II 29.9 +/- 11.9 and in grade III 41.1 +/- 8.6 mm Hg. 13 of the 21 patients in grade 0 or I had no manifest signs of pulmonary hypertension, but this was the case in only 6 of 22 in grade II and none in grade III. In 42 patients (69%) the systolic pulmonary artery pressure could be measured by DEC and it correlated well with the values obtained by cardiac catheterization (P < 0.001, r = 0.92). These findings show that DEC can provide semiquantitative and, in most cases, even exact evidence of chronic right ventricular overload.

Sitting position for neurosurgery: experience with preoperative contrast echocardiography in 301 patients

A persisting foramen ovale (PFO) is the most common cause of paradoxical air embolism. To detect right-to-left shunting, transthoracic contrast echocardiography was performed preoperatively in 301 patients scheduled for neurosurgical procedures in the sitting position. Echocardiography yielded evaluable results in 285 patients (94.7%). In 72 of 285 patients (25.2%), a PFO was diagnosed on the basis of contrast echo signals appearing in the left atrium or ventricle within 5 heart cycles after application of contrast medium via a peripheral vein. If echo signals appeared in the left heart after more than 5 heart cycles, an intrapulmonary right-to-left shunt was considered (11 patients, 3.9%). Venous air embolism (VAE) occurred in 27.4% of 226 patients operated on in the sitting position and in none of the 59 patients operated on in a nonsitting position. We conclude that the sitting position during neurosurgery should be avoided in patients with preoperative evidence of a right-to-left shunt at contrast echocardiography to reduce the risk of paradoxical air embolism (PAE).

Radionuclide detection of mild valvular regurgitation: its significance as assessed by Doppler sonography

Radionuclide ventriculography (RNV) indices of regurgitation, Fourier amplitude ratio (FAR) and additional RNV variables were prospectively compared to Doppler echocardiography (DE) in 108 consecutive patients with no or mild left ventricular regurgitation, to assess RNV accuracy in detecting regurgitation in patients with different cardiac disorders. Exclusion of left ventricular or tricuspid regurgitation allowed investigation of the FAR range at rest and during exercise in a sufficiently large appropriate reference group without regurgitation. FAR, as well as other RNV variables, failed to provide more information for the diagnosis of mild (clinically irrelevant) left ventricular regurgitation than the diagnosis upon admission alone. Despite the superiority of DE as a gold standard in the detection of mild regurgitation, at present evaluation of RNV regurgitation indices might be the only method to discover regurgitation arising during dynamic exercise.