Genesis of improved quality in imaging through a national Australian echocardiography registry.

BACKGROUND: Despite rapid technological advances and growth, quality in imaging has not received the focus seen elsewhere in cardiovascular medicine, resulting in significant gaps between guidelines and practice. Contemporary echocardiography practice requires comprehensive real-time data collection to allow dynamic auditing and benchmarking of key performance indices. The American College of Cardiology (ACC) proposed additional data standardisation, structured reporting identifying key data elements and imaging registries. In the absence of an Australian echocardiography registry, we developed a national clinical quality registry (GenesisCare Cardiovascular Outcomes Echo Registry). We hypothesised that measurement and local reporting of data would improve compliance of echo studies with quality guidelines and hence their clinical value. METHODS AND RESULTS: We prospectively collected data on 4 099 281 echocardiographic studies entered directly into a central electronic database from 63 laboratories across four Australian states between 2010 and 2021. Real-time auditing of key data elements and introduction of quality improvement pathways were performed to maximise completeness and uniformity of data acquisition and reporting. We compared completeness of key data element acquisition (AV peak velocity, left ventricular ejection fraction, E/e', LA area, rhythm, RVSP) by time and state using de-identified data. Key performance outcomes benchmarked against the aggregated study cohort and international standards were reported to individual sites to drive quality improvement. Between 2010 and 2014 there were significant improvements in data completeness (72.0%+/-26.8% vs 86.8%+/-13.5%, p=0.02), which were maintained to 2020. In addition, interstate variability fell for both EF and E/e' (p<0.002). CONCLUSIONS: This large-scale collaboration provides a platform for the development of major quality improvement initiatives in echocardiography. Introduction of local quality assurance programmes via a unified national data set significantly improved the completeness of reporting of key echo quality measures. This in turn significantly improved the quality of, and reduced the interstate variability of, echo data. Developing a centralised database allowed rapid adoption nationally of local quality improvements.

Long-term outcomes of the arterial switch operation.

OBJECTIVES: The arterial switch operation (ASO) has excellent early outcomes in the modern era. We sought to determine the long-term outcomes in patients who underwent an ASO at a single institution. METHODS: Patients who underwent an ASO between 1983 and 2015 were identified from the hospital database and retrospectively reviewed using hospital records. RESULTS: From 1983 to 2015, 844 patients with a biventricular circulation underwent an ASO. There were 28 (3.3%, 28/844) early deaths. Follow-up was available for 94% (729/774) of local patients after hospital discharge. Median follow-up was 15 years (interquartile range, 8-20 years). There were 187 (26%, 187/729) patients with more than 20 years of follow-up and 95 (13%, 95/729) patients with more than 25 years of follow-up. Overall survival was 95% (95% confidence interval [CI], 94%-97%) at 10 and 25 years after the ASO. At 25 years after ASO, freedom from overall reintervention was 77% (95% CI, 73%-81%), freedom from reoperation on the neoaortic root or neoaortic valve was 92% (95% CI, 88%-95%), and freedom from coronary reoperation was 99% (95% CI, 98%-99.7%). Left ventricular (LV) systolic function was normal in 595 of 609 (98%) of patients who had LV function quantified at latest follow-up. Of the 95 patients with more than 25 years of follow-up after ASO, 6 (6.3%) had at least moderate neoaortic valve regurgitation (AR) and 8 (8.4%) had undergone replacement of the neoaortic valve. CONCLUSIONS: Overall, survivors of ASO have excellent late survival and normal LV systolic function into adult life. However, AR and reoperation on the neoaortic valve remains an issue for older patients.

Path ahead for 'low risk' adolescents living with a Fontan circulation.

OBJECTIVE: A high risk of morbidity and mortality is well documented in adults with a Fontan circulation. The difference in outcomes between those with and without significant morbidity at the time of transition to adult care has not been well characterised. METHODS: We analysed clinical outcomes in patients enrolled in the Australian and New Zealand Fontan Registry ≥16 years of age. Low risk (LR) Fontan patients were defined as those without history of sustained arrhythmia, thromboembolic event, transplantation, Fontan conversion, protein-losing enteropathy, plastic bronchitis, New York Heart Association class III/IV and/or moderate/severe atrioventricular valve regurgitation or ventricular dysfunction. Increased risk (IR) patients had one or more risk factor. RESULTS: Inclusion criteria were met in 822 patients; mean age 26±8 years, median follow-up from age 16 was 9 years, 203 had atriopulmonary connection (APC) and 619 had total cavopulmonary connection (TCPC). Survival at 30 years was higher in the LR versus IR; 94% versus 82% (p=0.005), 89% versus 77% (p=0.07) for APC and 96% versus 89% (p=0.05) for TCPC. LR patients experienced less Fontan failure (HR 0.34, 95% CI 0.23 to 0.49, p<0.001) and ventricular dysfunction (HR 0.46, 95% CI 0.29 to 0.71, p=0.001) compared with IR patients. For LR TCPC patients, modelled survival projections at 60 years were 49%-67%. CONCLUSIONS: Clinical outcomes for adolescents LR at transition to adult care are markedly superior to those who have established risk factors for Fontan failure, which is an important consideration when formulating individualised long-term risk estimates and counselling patients.

Fontan-associated nephropathy: Predictors and outcomes.

BACKGROUND: Nephropathy is a known complication of the Fontan circulation, but its determinants have not been identified and patient outcomes are also still unknown. METHODS: The Australia and New Zealand Fontan Registry was used to identify those who underwent Fontan operation before and survived beyond 16-years-old with an intact Fontan circulation. Serum creatinine values were collected for each patient between 16 and 25 years and at recent follow-up. The Modification of Diet in Renal Disease (MDRD) equation was used to calculate eGFR. Patient outcomes were obtained from the Registry. Fontan failure was defined as death, transplantation, plastic bronchitis, protein losing enteropathy, Fontan takedown and NYHA class III-IV. RESULTS: Serum creatinine measurements were available for 328 patients. Renal dysfunction was defined as eGFR <90 mL/min/1.72m2. Renal dysfunction was present in 67/328 (20%) and 3/328 (1%) patients had an eGFR <60 mL/min/1.72m2. The 10-year survival and 10-year freedom from death and transplantation were the same, 96% (95% CI: 0.9-1) for those with renal dysfunction, and 89% (0.83-0.95; p = 0.1) and 87% (95% CI: 0.81-0.94; p = 0.05) for patients without dysfunction. The 10-year freedom from failure were also similar, 83% (95% CI: 0.70-0.97) for those without renal dysfunction vs 80% (95% CI: 0.74-0.89; p = 0.84). There was no change in mean eGFR for the renal dysfunction group over a mean of 8 ± 5.5 years. CONCLUSION: By the time they reach adulthood, 20% of patients with a Fontan circulation have renal dysfunction by eGFR calculation. Over the course of one decade, Fontan-associated nephropathy appears well tolerated.

Reintervention and survival in 1428 patients in the Australian and New Zealand Fontan Registry.

OBJECTIVE: Patients undergoing single-ventricle palliation have experienced significant improvement in survival in the recent era. However, a substantial proportion of these patients undergo reoperations. We performed a review of the Australia and New Zealand (ANZ) Fontan Registry to determine the overall reintervention and reoperative burden in these patients. METHODS: A retrospective longitudinal cohort study was performed using data from patients who underwent a Fontan operation between 1975 and 2016 from the ANZ Fontan Registry. The data obtained included Fontan operation, reinterventions and most recent follow-up status. We examined the type and timing of reinterventions and survival. RESULTS: Of the 1428 patients identified, 435 (30%) underwent at least one reintervention after the Fontan operation: 110 patients underwent early reintervention and 413 underwent late reinterventions. Excluding Fontan conversion and transplantation, 220 patients underwent at least one interventional procedure and 209 patients underwent at least one reoperation. Fenestration closure and pacemaker-related procedures were the most common catheter and surgical interventions, respectively. The cumulative incidence of reintervention following Fontan was 23%, 37% and 55% at 10, 20 and 30 years, respectively. Survival and freedom from failure were worse in patients requiring later reintervention after Fontan surgery (51% vs 83% and 42% vs 69%, respectively at 30 years, p<0.001). This difference persisted after excluding pacemaker-related procedures (p<0.001). Operative mortality for non-pacemaker late reoperations after Fontan was 6%. CONCLUSIONS: A substantial proportion of Fontan patients require further intervention to maintain effective single-ventricle circulation. Patients undergoing reoperation after Fontan have higher rates of mortality and failure, despite intervention.

Pacemakers are associated with a higher risk of late death and transplantation in the Fontan population.

BACKGROUND: The need for permanent pacing has been identified as a predictor of poor outcomes in the late survivors of Fontan surgery. However, it is not clear if the need for a pacemaker is a surrogate marker of a declining Fontan state, or if pacing is deleterious to the Fontan circulation. OBJECTIVES: We sought to compare the long-term outcomes of propensity-matched Fontan patients with and without a permanent pacemaker. METHODS: Patients who have survived Fontan completion with a documented history of cardiac arrhythmia were identified from the Australia and New Zealand Fontan Registry. Pacemaker insertion details, cardiac function and electrophysiological data were obtained for the patients with a permanent pacemaker. Survival analysis was performed with propensity score matching to compare late survival and outcomes in patients with versus without a pacemaker. RESULTS: There was a total of 310 patients with a history of cardiac arrhythmia, of which 126 (41%) had a permanent pacemaker. After propensity-score matching, 99 pairs were generated (n = 198). Patients with a permanent pacemaker had a higher risk of death (HR 3.32 95% CI 1.60-6.90, p = 0.001) and death or transplantation (HR 3.55 95% CI 1.87-6.73, p < 0.001). Patients who were only paced atrially were not at a significantly increased risk of death or transplantation. However, patients who were ventricular paced >50% of the time were much more likely to encounter late death or transplantation (HR 3.82 95% CI 1.64-8.95, p = 0.002). CONCLUSIONS: Having a permanent pacemaker and needing ventricular pacing is likely associated with an increased risk of death and transplantation in patients with a Fontan circulation.

Atrioventricular Valve Failure in Fontan Palliation.

BACKGROUND: Atrioventricular valve failure (moderate or greater regurgitation, or valve operation) is a risk factor for adverse outcomes in patients undergoing Fontan palliation. OBJECTIVES: This study determined the incidence of atrioventricular valve failure and its clinical impact on patients undergoing Fontan palliation. METHODS: A retrospective cohort longitudinal study was conducted using patient data extracted from an existing bi-national, population-based registry. RESULTS: A total of 1,468 patients who underwent Fontan palliation were identified; complete follow-up data were available for 1,199 patients. Six hundred eighty-six patients had 2 atrioventricular valves, 286 had a single mitral valve, 130 had a common atrioventricular valve, and 97 had a single tricuspid valve. A total of 132 repairs were performed in 110 patients, and 15 replacements were performed in 13 patients. The cumulative incidence of atrioventricular valve failure at 25 years of age for patients with a common atrioventricular, single tricuspid, single mitral, and 2 atrioventricular valves was 56% (95% confidence interval [CI]: 46% to 67%), 46% (95% CI: 31% to 61%), 8% (95% CI: 4% to 12%), and 26% (95% CI: 21% to 30%), respectively. In patients without valve failure, freedom from Fontan failure at 10 and 20 years post-Fontan palliation was 91% (95% CI: 89% to 93%) and 77% (95% CI: 73% to 81%), respectively, compared with 77% (95% CI: 69% to 85%) and 54% (95% CI: 42% to 68%), respectively, in patients with valve failure (hazard ratio: 2.43; 95% CI: 1.74 to 3.39; p < 0.001). CONCLUSIONS: Atrioventricular valve failure occurs frequently in patients undergoing Fontan palliation. Patients with valve failure are twice as likely to have their Fontan circulation fail than those without valve failure.

Adult Congenital Heart Disease in Australia and New Zealand: A Call for Optimal Care.

BACKGROUND: Adult congenital heart disease (ACHD) is a relatively new subspecialty in the cardiology field. The prevalence of ACHD is estimated at ∼ 3,000 per million adult population. The ACHD patient group is estimated to grow at ∼ 5% per year and in the next decade it is forecast that 1 in 150 young adults will carry some form of ACHD diagnosis. These estimates translate to ∼ 72,000 ACHD patients in Australia and ∼ 14,000 in New Zealand, although no current numbers are available. The Cardiac Society of Australia and New Zealand (CSANZ) has recently published Recommendations for Standards of Care for Adult Congenital Heart Disease (ACHD) in 2016. There is currently no long-term plan or proposal to address this huge health care burden within the federal government. This document details the size of the problem insofar as it is known and recommends solutions to be implemented. METHODS: This document was developed by the Adult Congenital Heart Disease Working Group of the Paediatric and Congenital Council (the Congenital Heart Alliance of Australia and New Zealand) as a response to the chronic under resourcing in this area, the risk this poses to patients and clinicians, and the clear need for long-term planning to develop safe care pathways. RESULTS: These issues were raised with the CSANZ Board in December 2015 and the document was developed in response to the Board's request for more information. The current iteration was finalised on 14 November 2017. CONCLUSIONS: The authorship group comprised participants in the CSANZ adult CHD standards of care recommendations from 2013 with the inclusion of some newly trained ACHD cardiologists, who represented most states and territories across ANZ. None of the authors has any academic or professional conflict of interest.

Clinical Outcomes in Adolescents and Adults After the Fontan Procedure.

BACKGROUND: Long-term outcomes of Fontan patients who survive to age ≥16 years have not been well characterized. The Australian and New Zealand Fontan Registry (ANZFR) provides a unique opportunity to understand survival and complication rates in Fontan patients who transition to adult congenital heart disease centers. OBJECTIVES: This study sought to describe the survival and complications of adult patients who have had a Fontan procedure. METHODS: The study analyzed outcomes in patients ≥16 years of age who were prospectively enrolled in the ANZFR. RESULTS: Data from all 683 adult survivors from the ANZFR were analyzed. Mortality status was confirmed from the National Death Index. There were 201 atriopulmonary (AP) connections and 482 total cavopulmonary connections (249 lateral tunnels and 233 extracardiac conduits). For these subjects, the survival rate at age 30 years was 90% (95% CI: 87% to 93%), and it was 80% (95% CI: 75% to 87%) at 40 years of age. Survival at age 30 years was significantly worse for the patients with AP connections (p = 0.03). At latest follow-up, only 53% of patients were in New York Heart Association functional class I. After the age of 16 years, 136 (20%) had experienced at least 1 new arrhythmia, 42 (6%) required a permanent pacemaker, 45 (7%) had a thromboembolic event, and 135 (21%) required a surgical reintervention. Only 41% (95% CI: 33% to 51%) of Fontan patients were free of serious adverse events at 40 years of age. CONCLUSIONS: This comprehensively followed cohort showed that a variety of morbid complications is common in Fontan adults, and that there is a substantial incidence of premature death, particularly in patients with AP connections.

CT sizing for left atrial appendage closure is associated with favourable outcomes for procedural safety.

AIMS: We evaluated the utility of computerized tomography (CT) with respect to sizing work-up for percutaneous left atrial appendage (LAA) closure, and implications for procedural safety and outcomes. METHODS AND RESULTS: Contrast-enhanced multi-detector CT was routinely conducted to guide sizing for LAA closure in addition to transoesophageal echocardiography (TOE). Procedural safety and efficacy were prospectively assessed. Across 73 consecutive cases there were no device-related procedural complications, and no severe leaks. Systematic bias in orifice sizing by TOE vs. CT was significant on retrospective analysis (bias -3.0 mm vs. maximum diameter on CT; bias -1.1 mm vs. mean diameter on CT). Importantly, this translated to an altered device size selection in more than half of all cases, and median size predicted by CT was one interval greater than that predicted by TOE (27 mm vs. 24 mm). Of particular note, gross sizing error by TOE vs. CT was observed in at least 3.4% of cases. Degree of discrepancy between TOE and CT was correlated with LAA orifice eccentricity, orifice size, and left atrial volume. Mean orifice size by CT had the greatest utility for final Watchman device-size selection. CONCLUSIONS: In this single-centre registry of LAA closure, routine incorporation of CT was associated with excellent outcomes for procedural safety and absence of major residual leak. Mean orifice size may be preferable to maximum orifice size. A particular value of CT may be the detection and subsequent avoidance of gross sizing error by 2D TOE that occurs in a small but important proportion of cases.

Left Atrial Appendage Eccentricity and Irregularity Are Associated With Residual Leaks After Percutaneous Closure.

OBJECTIVES: Predictors of residual leak following percutaneous LAA closure were evaluated. BACKGROUND: Left atrial appendage (LAA) closure aims to exclude this structure from the circulation, typically using a circular occluder. A noncircular orifice is frequently encountered however, and fibrous remodeling of the LAA in atrial fibrillation may restrict orifice deformation. Noncircularity may thus be implicated in the occurrence of residual leak despite an appropriately oversized device. METHODS: Pre-procedural multislice computerized tomography was used to quantify LAA orifice eccentricity and irregularity. Univariate predictors of residual leak were identified with respect to the orifice, device, and relevant clinical variables, with the nature of any correlations then further evaluated. RESULTS: Eccentricity and irregularity indexes of the orifice in 31 individuals were correlated with residual leak even where the device was appropriately oversized. An eccentricity index of 0.15 predicted a residual leak with 85% sensitivity and 59% specificity. An irregularity index of 0.05 predicted a significant residual leak ≥3 mm with 100% sensitivity and 86% specificity. Orifice size, device size, degree of device oversize, left atrial volume, and pulmonary artery pressure were not predictors of residual leak. CONCLUSIONS: Eccentricity and irregularity of the LAA orifice are implicated in residual leak after percutaneous closure even where there is appropriate device over-size. Irregularity index in particular is a novel predictor of residual leak, supporting a closer consideration of orifice morphology before closure.

Dramatic improvement in decompensated right heart failure due to severe tricuspid regurgitation following ligation of arteriovenous fistula in a renal transplant recipient.

Arteriovenous (AV) fistulas with high blood flow rate are necessary for adequate hemodialysis, but they can also cause significant hemodynamic changes, including raised cardiac output, left ventricular hypertrophy and occasionally overt cardiac failure (Basile et al., Nephrol Dial Transplant, 23, 2008, 282; Unger et al., Am J Transplant, 4, 2004, 2038). We now report a case of rapid and dramatic improvement in symptomatic right heart failure due to severe tricuspid regurgitation following ligation of an arteriovenous fistula. Cardiac magnetic resonance imaging (MRI) performed before and after the ligation of fistula showed striking improvement in both the tricuspid regurgitation and right ventricular dimensions, with minimal impact on left ventricular mass, size, and function.

Aortic plaque defined by contrast transthoracic echocardiography.

The authors explore the use of third generation echo contrast to define plaque in the ascending aorta and exclude more invasive procedures.

Assessment of atrial septal defects in adults comparing cardiovascular magnetic resonance with transoesophageal echocardiography.

BACKGROUND: Many adult patients with secundum-type atrial septal defects (ASDs) are able to have these defects fixed percutaneously. Traditionally, this has involved an assessment of ASD size, geometry and atrial septal margins by transoesophageal echocardiography (TOE) prior to percutaneous closure. This is a semi-invasive technique, and all of the information obtained could potentially be obtained by non-invasive cardiovascular magnetic resonance (CMR). We compared the assessment of ASDs in consecutive patients being considered for percutaneous ASD closure using CMR and TOE. METHODS: Consecutive patients with ASDs diagnosed on transthoracic echocardiography (TTE) were invited to undergo both CMR and TOE. Assessment of atrial septal margins, maximal and minimal defect dimensions was performed with both techniques. Analyses between CMR and TOE were made using simple linear regression and Bland Altman Analyses. RESULTS: Total CMR scan time was 20 minutes, and comparable to the TOE examination time. A total of 20 patients (M:F = 5:15, mean age 42.8 years +/- 15.7) were included in the analyses. There was an excellent agreement between CMR and TOE for estimation of maximum defect size (R = 0.87). The anterior inferior, anterior superior and posterior inferior margins could be assessed in all patients with CMR. The posterior superior margin could not be assessed in only one patient. Furthermore, in 1 patient in whom TOE was unable to be performed, CMR was used to successfully direct percutaneous ASD closure. CONCLUSIONS: CMR agrees with TOE assessment of ASDs in the work-up for percutaneous closure. Potentially CMR could be used instead of TOE for this purpose.

Percutaneous closure of atrial septal defects leads to normalisation of atrial and ventricular volumes.

BACKGROUND: Percutaneous closure of atrial septal defects (ASDs) should potentially reduce right heart volumes by removing left-to-right shunting. Due to ventricular interdependence, this may be associated with impaired left ventricular filling and potentially function. Furthermore, atrial changes post-ASD closure have been poorly understood and may be important for understanding risk of atrial arrhythmia post-ASD closure. Cardiovascular magnetic resonance (CMR) is an accurate and reproducible imaging modality for the assessment of cardiac function and volumes. We assessed cardiac volumes pre- and post-percutaneous ASD closure using CMR. METHODS: Consecutive patients (n = 23) underwent CMR pre- and 6 months post-ASD closure. Steady state free precession cine CMR was performed using contiguous slices in both short and long axis views through the ASD. Data was collected for assessment of left and right atrial, ventricular end diastolic volumes (EDV) and end systolic volumes (ESV). Data is presented as mean +/- SD, volumes as mL, and paired t-testing performed between groups. Statistical significance was taken as p < 0.05. RESULTS: There was a significant reduction in right ventricular volumes at 6 months post-ASD closure (RVEDV: 208.7 +/- 76.7 vs. 140.6 +/- 60.4 mL, p < 0.0001) and RVEF was significantly increased (RVEF 35.5 +/- 15.5 vs. 42.0 +/- 15.2%, p = 0.025). There was a significant increase in the left ventricular volumes (LVEDV 84.8 +/- 32.3 vs. 106.3 +/- 38.1 mL, p = 0.003 and LVESV 37.4 +/- 20.9 vs. 46.8 +/- 18.5 mL, p = 0.016). However, there was no significant difference in LVEF and LV mass post-ASD closure. There was a significant reduction in right atrial volumes at 6 months post-ASD closure (pre-closure 110.5 +/- 55.7 vs. post-closure 90.7 +/- 69.3 mL, p = 0.019). Although there was a trend to a decrease in left atrial volumes post-ASD closure, this was not statistically significant (84.5 +/- 34.8 mL to 81.8 +/- 44.2 mL, p = NS). CONCLUSION: ASD closure leads to normalisation of ventricular volumes and also a reduction in right atrial volume. Further follow-up is required to assess how this predicts outcomes such as risk of atrial arrhythmias after such procedures.

Prevalence of migraine in adults with cyanotic congenital heart disease.

OBJECTIVE: There is an increased prevalence of patent foramen ovale in patients with migraine, leading to the suggestion that migraine is more common in patients with potential right-to-left shunts. The aim of this study was to investigate the prevalence of migraine in adults with large right-to-left shunts because of cyanotic congenital heart disease. DESIGN AND PATIENTS: In total, 29 cyanotic adult patients with congenital heart disease answered a questionnaire to determine the prevalence of migraine with or without aura. A total of 38 matched acyanotic patients with congenital heart disease served as controls. A subgroup of 18 acyanotic patients also underwent bubble contrast echocardiography to look for patent foramen ovale. RESULTS: Twenty (69%) of the cyanotic patients had migraine, the majority 17 (59%) having migraine with aura. Twenty-two (58%) of the 38 acyanotic patients had migraine, of whom 16 (42%) had migraine with aura. Nine (50%) of the 18 acyanotic patients who consented to an echocardiogram had patent foramen ovale. Of those with patent foramen ovale, 8 (89%) had migraine and 6 (67%) had migraine with aura. CONCLUSION: There is an increased prevalence of migraine with aura in both cyanotic and acyanotic patients with congenital heart disease. The high prevalence of migraine in acyanotic patients with congenital heart disease may be due to an increased prevalence of patent foramen ovale.

Differential effects of intravenous magnesium on atrioventricular node conduction in supraventricular tachycardia.

Evidence from noninvasive studies suggests magnesium has a differential effect on atrioventricular nodal (AVN) pathways. To further explore the electrophysiologic effects of intravenous magnesium sulfate (MgSO(4)) on supraventricular tachycardia, with particular reference to AVN conduction pathways, we studied 23 patients with supraventricular tachycardia at the time of electrophysiologic study. Tachycardia cycle length; AH, HV, and VA intervals; anterograde and retrograde Wenckebach thresholds; slow and fast pathway effective refractory periods (ERPs); accessory pathway ERP; right atrial and ventricular ERPs; blood pressure; and serum magnesium were evaluated before and after administration of MgSO(4) during sustained tachycardia. AVN reentry was induced in 14 patients and atrioventricular reentry was induced in 9; 1 of the latter had dual AVN physiology with tachycardia using the slow pathway. Serum magnesium level increased from 0.88 +/- 0.11 to 1.79 +/- 0.14 mmol/L (p <0.0001). Magnesium increased tachycardia cycle length to a greater extent in those with dual AVN physiology than those without: 340 +/- 54 to 370 +/- 57 ms versus 347 +/- 29 to 350 +/- 30 ms (p = 0.01). This was associated with greater increase in AH interval in those with dual AVN physiology than in those without: 241 +/- 59 to 270 +/- 60 ms versus 144 +/- 16 to 140 +/- 20 ms (p = 0.003). Presence of dual AVN physiology was more frequently associated with reversion to sinus rhythm: 5 of 15 versus 0 of 8 (p = 0.06). MgSO(4) did not alter other measured parameters. In conclusion, magnesium increases tachycardia cycle length and AH interval in patients with dual AVN physiology through a dominant effect on the slow AVN pathway.

Transthoracic echocardiography to identify or exclude cardiac cause of shock.

BACKGROUND: Transesophageal echocardiography (TEE) is often still considered the echocardiographic test of choice in the general ICU patient population to establish the presence or absence of cardiac cause of shock, and is often requested and performed as the initial and only echocardiographic test. This premise is based on older studies in which transthoracic echocardiography (TTE) commonly offered inadequate images in ICU patients. STUDY OBJECTIVES: We hypothesized that current TTE imaging alone is adequate to identify or exclude cardiac cause of shock in the great majority of cases. METHODS: One hundred consecutive shock cases in which an echocardiogram was requested were prospectively analyzed by two blinded echocardiographers for image adequacy, and the absence or presence of cardiac cause of shock (defined as one or more of the following: severe left ventricular (LV) or right ventricular systolic dysfunction, tamponade, severe left-sided valve disease, or a postinfarction mechanical complication), and compared to a clinical standard of presence/absence of cardiac cause of shock as determined by autopsy, surgery, or objective testing. Shock was defined as systolic BP < 100 mm Hg or fall in BP >/= 25%, and inotrope use or evidence of low output or venous congestion. Cardiac output was determined by the LV outflow tract (LVOT) Doppler method. RESULTS: Sixty-three percent of cases had a cardiac cause of shock. TTE image quality was adequate in 99% cases. Among the 99% of cases in which the imaging was adequate, the sensitivity of TTE for cardiac cause of shock was 100%, the specificity was 95%, the positive predictive value was 97%, and the negative predictive value was 100%. There were relative contraindications to TEE in 15% of cases. Stroke volume index (15 +/- 6 mL/m(2) vs 31 +/- 7 mL/m(2) [mean +/- 1 SD]; p < 0.001) and cardiac index (1.6 +/- 0.5 mL/min/m(2) vs 2.9 +/- 0.9 mL/min/m(2); p < 0.001) were significantly less in the group with a cardiac cause of shock than in the group with a noncardiac cause of shock. CONCLUSIONS: In the general critical care population, current TTE imaging identifies the great majority of cardiac causes of shock. TTE should be considered not only the initial, but also the principal echocardiographic test in the critical care environment.

Biventricular pacing for severe mitral regurgitation following atrioventricular nodal ablation.

A 69-year-old woman developed acute pulmonary edema and severe mitral regurgitation (MR) 2 days following an uncomplicated AV nodal (AVN) ablation and insertion of VVI pacemaker for chronic atrial fibrillation. There was no history of significant mitral valve disease. Left ventricular function was normal and there was no evidence of an acute cardiac ischemic event. Transthoracic echo and right heart catheterization studies showed reduction in the severity of MR with biventricular pacing as opposed to RV pacing alone. A permanent pacemaker configured for biventricular pacing was implanted with complete resolution of symptoms and significant reduction in degree of MR.