Effect of simulated diving trips on pulmonary artery pressure in healthy men.

BACKGROUND: Environmental stresses, such as immersion, cold, and venous gas microbubbles, have been shown to contribute to an increase in pulmonary artery pressure (PAP) after single SCUBA dives. This study was carried out to investigate PAP changes following a dry chamber dive. METHODS: 17 male divers [mean age 32 years, standard deviation (SD) 7 years, mean body mass index 26 kg m(-2) (SD 3 kg m(-2))] participated in the study. Heart disease was ruled out by ECG, stress-ECG and transthoracic echocardiography in all subjects. Echocardiographic assessment of PAP (peak gradient at pulmonary and tricuspid valve), acceleration time (AT), ejection time (ET) and the ratio AT/ET as an estimate of PAP was performed directly prior to, directly, and 20 and 80 min after a simulated dive (maximal pressure 600 kPa, duration 60 min). RESULTS: AT/ET decreased from 0.40 (SD 0.03) to 0.34 (SD 0.03) directly after the dive (p = <0.0001), which was statistically significant, whereas 80 min after decompression, AT/ET tended to return to baseline levels (0.36, SD 0.03; p = 0.001). Other echocardiographic indices, e.g. ET, systolic PAP, and heart rate, did not change significantly after the dive. No gas microbubbles were detected during or after decompression. CONCLUSIONS: A transient decrease of both AT and AT/ET following a simulated hyperbaric dry chamber dive indicated an increase in mean PAP in healthy men. We speculate that factors other than immersion, cold, or gas microbubbles may contribute to an elevation of PAP after a single hyperbaric exposure.

Effect of simulated dives on diastolic function in healthy men.

Scuba diving may elicit acute changes to human cardiovascular function. Environmental stresses such as immersion, cold, and venous gas microbubbles all have been shown to contribute to right ventricular overload and impaired left ventricular filling after single dives. We investigated cardiac function after simulated dry chamber dives. Twenty male divers [mean age 31 years, standard deviation (SD) 8 years, mean body mass index 26 kgm(-2) (SD 3 kgm(-2))] participated in the study. All subjects had normal ECG, stress-ECG, and transthoracic echocardiography at rest. Echocardiographic assessment of diastolic function [E/A-ratio, deceleration time (DT), isovolumic relaxation time (IVRT), E/e'-ratio] was performed directly prior to and 20 and 80 min after two simulated dry hyperbaric chamber dives (maximal pressure 600 kPa, duration 60 min) that were conducted within 1 week. DT statistically significantly decreased from 163 ms (SD 14 ms) to 125 ms (SD 15 ms) 20 min after the dive (p < 0.0001), whereas 80 min after decompression these changes tended to return to baseline [146 ms (SD 14 ms); p = 0.06]. There was no statistically significant change in heart rate, E/A-ratio or E/e'-ratio after 20 or 80 min compared to baseline. These changes could be reproduced after the second dry chamber dive. No gas microbubbles were detectable during or after decompression from either dive. Simulated hyperbaric dry chamber dives were associated with a transient decrease in deceleration time in healthy men. Factors other than immersion, cold, or nitrogen microbubbles may contribute to acute changes in cardiac function after single scuba dives.

Acetazolamide-responsive exercise-induced episodic ataxia associated with a novel homozygous DARS2 mutation.

BACKGROUND: Leukoencephalopathy with brain stem and spinal cord involvement and brain lactate elevation (LBSL) was recently shown to be caused by mutations in the DARS2 gene, encoding a mitochondrial aspartyl-tRNA synthetase. So far, affected individuals were invariably compound heterozygous for two mutations in DARS2, and drug treatments have remained elusive. METHODS: Prospective 2-year follow-up of the natural history of the main presenting symptoms in a homozygous DARS2 mutation carrier, followed by a 60 day treatment with acetazolamide in two different doses and with two random treatment interruptions. RESULTS: The patient presented with exercise-induced paroxysmal gait ataxia and areflexia as an atypical phenotype associated with a novel homozygous DARS2 mutation. These features showed an excellent dose-dependent, sustained treatment response to a carbonic anhydrase inhibitor. Pathogenic mutations in episodic ataxia genes were excluded, thus making it highly unlikely that this phenotype was because of episodic ataxia as a second disorder besides LBSL. CONCLUSIONS: This case demonstrates that DARS2 mutation homozygosity is not lethal, as suggested earlier, but compatible with a rather benign disease course. More importantly, it extends the phenotypic spectrum of LBSL and reveals that at least some DARS2-associated phenotypic features might be readily treatable. However, future observations of paroxsymal ataxia and, possibly, areflexia in other DARS2-mutated patients are warranted to further corroborate our finding that DARS2 mutations can lead to a paroxsymal ataxia phenotype.

Cardiorespiratory fitness determines the reduction in blood pressure and insulin resistance during lifestyle intervention.

OBJECTIVE: Lifestyle intervention is not always effective for improving arterial hypertension and other cardiovascular risk factors, and the parameters determining the outcome are not known. Because high cardiorespiratory fitness (CRF) protects from cardiovascular disease and mortality, we determined whether CRF at baseline predicts the improvement of blood pressure and other cardiovascular risk factors during a lifestyle intervention. METHODS: A total of 219 patients at risk for type 2 diabetes, who underwent a 9-month lifestyle intervention with diet modification and increase in physical activity, and had measurement of CRF, were studied. Insulin sensitivity was estimated during a 75-g oral glucose tolerance test. Total body, visceral and liver fat were measured by magnetic resonance (MR) tomography and H-MR spectroscopy. CRF was estimated using two different methods, an incremental cycle exercise (maximal aerobic capacity-VO2max) test and a motorized treadmill (individual anaerobic threshold) test. RESULTS: After 9 months of intervention adiposity, glycemia, CRF, insulin sensitivity, SBP and serum lipids (except high-density lipoprotein cholesterol, P = 0.65) improved (all other P ≤ 0.006). DBP did not change significantly (P = 0.06). High CRF at baseline predicted decreases in SBP (P ≤ 0.0002) and DBP (P ≤ 0.004), and increase in insulin sensitivity (P ≤ 0.04), but not change in serum lipids (all P ≥ 0.06). For 1 SD increase in baseline CRF the odds ratio for resolution of hypertension or prehypertension was 2.26 (individual anaerobic threshold; 95% CI 1.40-3.80) and 1.75 (VO2max; 95% CI 1.08-2.89). CONCLUSION: CRF at baseline predicts the effectiveness of a lifestyle intervention in improving insulin sensitivity, and particularly blood pressure.

The pre-participation examination for leisure time physical activity: general medical and cardiological issues.

BACKGROUND: There is current debate on the appropriate type and extent of medical testing for amateur and hobby athletes before they engage in sports. In particular, views diverge on the value of an ECG at rest. METHODS: We selectively searched the Medline and Embase databases for relevant publications that appeared from 1990 to 2008. The most pertinent ones are discussed here along with current reviews and guidelines that give recommendations on pre-participation testing for amateur athletes. RESULTS: History-taking and physical examination are standard around the world. The American guidelines on pre-participation examination do not recommend an ECG at rest, yet the guidelines for most European countries explicitly recommend it. No prospective cohort studies have been performed to date that might provide high-grade evidence (class and level) to support this practice. We discuss the pros and cons of an ECG at rest and also present the guideline recommendations on exercise-ECG testing for amateur athletes over age 40. CONCLUSION: In accordance with the current European recommendations, and in consideration of the risks of athletic activity, we recommend that all persons participating in sports should undergo a pre-participation examination that includes an ECG at rest. Although primary-prevention campaigns advise physically inactive persons to get regular exercise, prospective studies are still lacking as a basis for recommendations in this group.

Hypoxia and cardiac arrhythmias in breath-hold divers during voluntary immersed breath-holds.

The incidence and nature of cardiac arrhythmias during static apnea were studied by monitoring the electrocardiogram (ECG) and oxygen saturation (SaO(2)) of 16 recreational breath-hold divers. All subjects completed a maximal apnea with a mean (+/-SD) breath-hold duration of 281 (+/-73) s without clinical complications. Both heart rate (HR) and SaO(2) decreased significantly with breath-hold duration. The decline in SaO(2) was inversely related to the decline in HR (r = -0.55, P < 0.05). Cardiac arrhythmias (supraventricular and ventricular premature complexes, right bundle branch block) occurred in 12/16 (77%) subjects and were related to breath-hold duration. Subjects with atrial premature complexes (n = 9) had a reduced BMI (P = 0.016) and a higher decline of the terminal SaO(2) (P = 0.01). In conclusion, ectopic arrhythmias were common during maximal static apneas for training purposes. The results indicate that the occurrence of ectopic beats is associated with individual factors such as the tolerable SaO(2) decrease.

Percutaneous pulmonary vein stenting for the treatment of severe stenosis after pulmonary vein isolation.

INTRODUCTION: Pulmonary vein stenosis (PVS) is a potential complication of pulmonary vein isolation (PVI) using radiofrequency energy. The aim of our study was the evaluation of the severity and long-term outcome of primary angioplasty and angioplasty with pulmonary vein stenting for PVS. METHODS AND RESULTS: Twelve patients with 15 PVS (greater than 70% stenosis) were prospectively evaluated. Primary dilation of the stenosis was performed because of clinical symptoms (10 patients) and/or the lung perfusion scans showed a significant perfusion defect (11 patients). Magnetic resonance imaging and lung perfusion scans performed before, directly after, during 3-month, and 6-month follow-up. In the stenting group additional multislice CT-scans directly after, during 6-month, and 12-month follow-up were performed. Within 2 months after primary balloon angioplasty, the PV size parameters were significantly reduced (P < 0.001) with recurrence of PVS in 11 of 15 PVs (73%). Pulmonary vein stenting in 8 patients and 11 PVs resulted in no vein stenosis during 12-month follow-up. Normalization of lung perfusion was noted in 8 of 12 patients. We observed 2 patients with hemoptysis during PV dilation, as severe complications with potential life-threatening character. CONCLUSION: PVS stenting seems to be superior to balloon angioplasty and effective at least over a period of 12 months in treating acquired PVS after pulmonary vein isolation.

Delayed contrast-enhanced magnetic resonance imaging for the detection of autoimmune myocarditis and long-term follow-up.

MRI proved to be a valuable tool for the evaluation and monitoring of myocarditis. We report the case of a 36 year old caucasian male with an undifferentiated collagenosis who presented first four years ago with unspecific symptoms and impaired exercise capacity. On echocardiography left ventricular function was impaired as well as on MRI. In addition, after administration of Gd-DTPA an intramyocardial pathological signal enhancement was observed on TSE T1 weighted and contrast enhanced FLASH 3D IR sequences. Based on several diagnostic tests including myocardial biopsy an autoimmune myocarditis due to an undifferentiated collagenosis was diagnosed. On long time follow up over almost 3 years with repeated MRI examinations, the delayed hyper enhancement (dHE) decreased or disappeared with successful treatment, respectively. However, in the area of recurrent inflammation, a persisting area of dHE developed with a subsequent perfusion defect. This area represents myocardial fibrosis due to recurrent inflammation.

Decreased pulmonary perfusion in pulmonary vein stenosis after radiofrequency ablation: assessment with dynamic magnetic resonance perfusion imaging.

STUDY OBJECTIVES: The functional impact of pulmonary vein (PV) stenosis on pulmonary perfusion after radiofrequency ablation (RFA) for atrial fibrillation (AF) has not been systematically evaluated previously. Therefore, we correlated magnetic resonance (MR) pulmonary perfusion imaging with single-photon emission CT (SPECT) perfusion and with the degree of PV stenosis (PVS) apparent on MR angiography (MRA) after RF ablation. SETTING: Joint radiology-cardiology collaborative magnetic resonance unit at the Kerckhoff Heart Center. DESIGN AND PATIENTS: This was a cohort study of 110 patients who were routinely examined by MRA after RFA for AF, whereby 51 patients with a PV diameter reduction of > 25% or with clinical symptoms (ie, dyspnea and cough) were enrolled into the study. Patients were examined at follow-up by MR perfusion imaging and MRA, and the results were compared to those from patients who underwent SPECT scanning and from a control group of 26 untreated patients. Twelve patients underwent PVS dilatation as well as 22 sequential follow-up examinations. METHODS: Pulmonary perfusion was evaluated using a dynamic contrast-enhanced three-dimensional MR perfusion sequence (1.5 T, 2.5-s temporal resolution, and 0.05 cm spatial resolution), and high-resolution, contrast-enhanced MRA was performed to measure PV diameter. PV dilatation was performed using an angioplasty catheter that was 8 to 10 mm in diameter. RESULTS: The localization and extent of perfusion defects measured by MRI or SPECT scanning were precisely matched. MR perfusion imaging detected 20 of 21 perfusion defects (sensitivity, 95.2%; specificity, 100%). PVSs and perfusion deficits correlated closely and showed the following threshold: perfusion decreased substantially in PVs 6 mm in diameter. After PVS dilatation, perfusion was restored partially after weeks, and complete normalization was seen in 4 of 12 patients (33%). CONCLUSIONS: PVSs caused severe perfusion deficits, which were reliably demonstrated by MR perfusion imaging. Clinical symptoms correlated better with MR perfusion than they did with MRA. The combination with MRA to assess underlying PVS allowed a "one-stop-shopping" MRI procedure to be carried out. The results led to alterations of RFA techniques, and therefore MRA and MR perfusion imaging may be beneficial in patient follow-up and in evaluating new ablation techniques.

Real-time MR with TrueFISP for the detection of acute pulmonary embolism: initial clinical experience.

The feasibility and diagnostic value of real-time magnetic resonance imaging (RT-MRI) for the diagnosis of acute pulmonary embolism (PE) was evaluated by comparing RT-MRI and magnetic resonance angiography (MRA). In 39 consecutive patients with suspected PE real-time true fast imaging with steady-state precession (TrueFisp) was prospectively compared with contrast-enhanced MRA on a 1.5-T MR scanner. The TrueFisp sequence used allowed acquisition of T2-weighted images at 0.4 s per image so that the pulmonary vasculature could be visualized in three orientations in <3 min without the need for breath holding or contrast media application. Results of additional scintigraphic pulmonary perfusion examinations were available from 17 patients. All 39 primary RT examinations (100%) and 30 of 39 MRA examinations (77%) were of diagnostic quality. The reasons underlying failure to achieve diagnostic quality for MRA were breathing artifacts among dyspneic patients in all 9 cases. Compared with MRA, the sensitivities and specificities of RT sequences for PE were 93 and 100% (per examination), 96 and 100% (lobar artery PE), and 97 and 100% (segmental artery PE), respectively. Compared with scintigraphy, the sensitivity and specificity of RT-MRI were 83 and 100%, respectively. The MRA reached 100% sensitivity and specificity in this subgroup. The RT-MRI proved to be very robust and undisturbed by respiratory movements and patient cooperation. Its image quality assured fast diagnostic examinations, and its sensitivity and specificity, compared with MRA and scintigraphy, were sufficient to allow the diagnosis of acute central, lobar, and segmental PE; therefore, the emergency diagnosis of PE using RT-MRI is feasible and reliable.