Hemodynamic analysis of descending versus ascending aortomyoplasty, and comparison with intra-aortic balloon pump

Objective: Descending and ascending aortomyoplasty are two surgical procedures intended to induce hemodynamic benefits similar to those of the intra-aortic-balloon-pump (IABP). To date, there have been no studies comparing the two surgical techniques. The objective of this study was to compare coronary blood flow augmentation and afterload reduction as produced by descending and ascending aortomyoplasty counterpulsation Methods: Twenty-two mongrel dogs (18–35 kg) underwent IABP application (n=7), descending (n=8), or ascending (n=7) aortomyoplasty. Left anterior descending (LAD) coronary artery blood flow was measured using a Transonic Doppler flow probe. Left ventricular pressure as well as aortic pressures proximal and distal to either the aortomyoplasty site or the IABP position were monitored continuously. Results: Descending aortomyoplasty induced higher elevation in the LAD blood flow during assisted beats (27% from 10.8±4 to 13.8±6 ml/min, P<0.001) than that induced by either ascending aortomyoplasty (19% from 11.7±5 to 14±5 ml/min, P<0.001) or IABP counterpulsation (18% from 8.6±3 to 10.2±4 ml/min, P<0.001). Conversely, while ascending aortomyoplasty reduced the left ventricular end-diastolic pressure by 16% (from 60±18 to 50±22 mmHg, P<0.001), similar to the 16% after load reduction achieved by the IABP counterpulsation, descending aortomyoplasty failed to induce afterload reduction. Conclusions: Descending aortomyoplasty produces higher coronary blood flow augmentation than either ascending aortomyoplasty or IABP. However, afterload reduction comparable to that achieved by IABP was observed only with ascending aortomyoplasty and not with descending aortomyoplasty.     

Failure modes of left ventricular reconstruction or the Dor procedure: a multi-institutional perspective.

BACKGROUND: Complex ventricular reconstruction (CVR) is now being employed increasingly thanks to the pioneering work of Dor. However, little is known about the failure mode of CVR. We present experience from three centres with CVR and an analysis of the failure modes. METHODS: Between January 1997 and February 2005, 284 patients underwent CVR in three centres in Australia and USA. All of the procedures were performed as adjuncts to coronary artery surgery and/or valvular surgery. Patients were followed-up clinically and/or echocardiographically. Failure modes were classified as fatal or non-fatal. Non-fatal failure mode (NFM) was defined as either persistent heart failure, recurrence of LV scar, need for ventricular assistance, persistent ventricular arrhythmia, or a combination. RESULTS: Operative mortality rate (OMR) was 8% (23 deaths). This fatal failure mode was most related to urgency of surgery and cardiogenic shock in 15 patients (5.3% of OMR), stroke in 5 patients (1.8%) or postoperative bi-ventricular failure (1%). Non-fatal failure modes accounted for morbidity in 26 patients (9%). This was predominantly due to persistent septal dyskinesis in 7 patients (2.46%), persistent mitral regurgitation in 5 (1.8%), postoperative ventricular tachycardia in 4 (1.4%), sub-optimal myocardial protection in 4 (1.4%) use of a large, stiff patch in 4 (1.4%). One hundred and ninety-nine of the surviving 261 patients (76%) were in NYHA Class I. CONCLUSIONS: Complex ventricular reconstruction is a robust technique that has lasting benefit. Failure modes have been identified and could be minimized by appropriate patient and procedure selection.     

Targeted Delivery of Doxorubicin via Sterically Stabilized Immunoliposomes: Pharmacokinetics and Biodistribution in Tumor-bearing Mice

Purpose. To evaluate benefits in tumor localization, availability, and noncancerous organ distribution of doxorubicin (DOX) delivered via small (120 nm) sterically stabilized immunoliposomes targeted against a tumor-associated antigen in fibrosarcoma-bearing mice. Methods. DOX-loaded liposomes were prepared with (i) specific monoclonal IgG₃ antibody (32/2, D-SSIL-32/2); (ii) non-specific IgG₃ (D-SSIL-IgG); or (iii) no IgG (D-SSL) on their surface. Equal DOX amounts were injected intravenously via each type of liposome into BALB/c mice carrying experimental lung metastases of a polyoma virus-induced fibrosarcoma (A9 etc 220) expressing a polyoma virus-induced tumor-associated antigen (PAA) on their surface. Metastases occurred mainly in lung. Mice were treated at 3 stages of tumor development (micrometastases, medium-size metastases, and large, necrotic metastases). Performance evaluation was based on time-dependent quantification of DOX and DOX metabolites (DOX-M) in lung tumor, noncancerous organs, and plasma. Results. (i) DOX delivered via both SSIL retained the prolonged circulation time typical of DOX delivered via D-SSL. (ii) DOX accumulation in noncancerous organs was similar for all preparations. Low levels of DOX-M were obtained for all three preparations in all organs except liver, suggesting a similar processing, (iii) Preparations differed in behavior in lung tumor depending on tumor size and microanatomy. Only at the micrometastases stage were the specifically targeted D-SSIL-32/2 superior to D-SSL and D-SSIL-IgG, delivering 2–4 times more drug into the tumor, (iv) DOX-M level in all three tumor stages was in the following order: D-SSIL-32/2 >> D-SSL >> D-SSIL-IgG, suggesting that DOX delivered as D-SSIL-32/2 is most available to tumor cells. Conclusions. The advantage of specific targeting of sterically stabilized liposomes is expressed mainly in increasing availability of DOX to tumor cells in a way which is dependent on tumor microanatomy. The impact of this advantage to therapeutic efficacy remains to be determined.     

Robot-assisted epicardial ablation of the pulmonary veins: is a completed isolation necessary?

AIMS: To study the feasibility and electrophysiological efficacy of minimally invasive beating heart ablation of the pulmonary veins (PVs) via a robot-assisted single-sided approach. BACKGROUND: PV isolation by minimally invasive epicardial ablation may offer a new treatment for patients with lone atrial fibrillation (AF). However, complete PV isolation has been shown to be difficult to obtain. METHODS AND RESULTS: In 14 mongrel dogs, robot-assisted epicardial microwave ablation was performed on the beating heart by a single-sided right chest approach. Isolation of all PVs was performed in two steps to study the effect of an incomplete and a complete isolation on AF. AF was studied by random and burst pacing. Incremental pacing was performed to study conduction characteristics across the lesions. Opening of the pericardial reflections, introduction of the catheter and ablation were robotically feasible by a single-sided approach in 11 dogs. The AF duration decreased from 6.6+/-4.1 to 1.3+/-0.8 s (P=0.03) and 1.6+/-1.6 s (P=0.04 compared with control) after incomplete and completed isolation of the PVs. The AF cycle length increased from 134+/-5 to 141+/-5 and 145+/-8 ms (P=0.03) after incomplete and complete isolation, respectively. Several incomplete lesions showed 2:1 exit and/or entrance block during incremental pacing. After complete isolation, AF was no longer inducible from the PVs. CONCLUSION: Epicardial PV isolation can be successfully performed by a single-sided robot-assisted approach. The effect of PV ablation on AF is not an all or none phenomenon. Incomplete isolation already decreases AF duration and lengthens the AF cycle length. However, complete isolation is necessary to prevent AF induction by triggering from the isolated area.     

CLINHAQ Scale – Validation of a Hebrew Version in Patients with Fibromyalgia

Assessment of health status in patients with rheumatic disease, including fibromyalgia (FM), using structured questionnaires has become an important approach to evaluate treatment and outcome. The objectives of this study were to validate a translated version of the Clinical Health Assessment Questionnaire (CLINHAQ) to be used by Hebrew-speaking populations, and specifically to evaluate its usefulness in fibromyalgia syndrome (FM). The CLINHAQ was translated into Hebrew and administered to 90 women with FM along with the Hebrew versions of the Fibromyalgia Impact Questionnaire (FIQ) and the Quality of Life (QOL) Scale. The CLINHAQ includes scales of functional disability, helplessness, anxiety and depression, as well as assessment of current health status and satisfaction with this. All subjects were asked about the presence and severity (assessed by visual analogue scale) of current FM symptoms (pain, fatigue, anxiety etc.); a count of 18 tender points was conducted by thumb palpation, and tenderness thresholds were measured by dolorimetry. Test–retest reliability was assessed by Pearson correlation coefficients, and internal consistency was evaluated with Cronbach’s α coefficient of reliability. Construct validity was tested by correlating the CLINHAQ items with measures of symptom severity, count of tender point, tenderness thresholds, physical functioning measured by FIQ, and with a score of QOL. Test–retest reliability coefficients ranged from 0.82 to 0.99, and Cronbach’s α coefficients from 0.725 to 0.929. Significant moderate to high correlations were obtained between most subscales of CLINHAQ and measures of physical functioning, quality of life and severity of FM symptoms. In conclusion, the CLINHAQ is a reliable and valid instrument for measuring health status and physical functioning in Israeli women with FM. Received: 22 June 1999 / Accepted: 24 September 1999     

Exploring the reasons for low pertussis vaccine effectiveness in Ontario,Canada, 2006–2008: a Canadian Immunization Research Network study

ObjectivesAlthough pertussis vaccines have been widely used for many decades, a burden of illness persists. Resurgences in Ontario, Canada, have not been substantial in the past decade, but an outbreak of pertussis occurred in Toronto between 1 October 2005 and 31 March 2006. Previous Ontario studies found high vaccine effectiveness (VE) in the initial years post-immunization. In order to explore the impact of outbreaks and external factors on VE, we investigated pertussis VE during the period 2006–2008.MethodsWe assessed pertussis VE using a frequency-matched case-control study for the period 1 March 2006 to 31 December 2008. We used logistic regression to estimate VE by age, time since last vaccination, and vaccination status according to the Ontario recommended schedule. We compared analyses including and excluding cases from Toronto, and to two recent Ontario pertussis VE studies.ResultsWe included 1797 confirmed cases and 7188 matched controls. Most cases were under 4 years of age during the study period. Pertussis VE was 3.8% (95% CI: − 21.0, 24.0) in the period 15–364 days following the last pertussis vaccine dose, and increased with increasing time since vaccination. Pertussis VE in the first 15–364 days excluding Toronto increased to 57.1% (95% CI: 26.0, 75.1), but the trend of increasing VE with time since vaccination persisted. Although VE was higher in older (6–11 years) than younger (0–5 years) children, it was lower at 12–13 years than after 14 years.ConclusionVE was lower in comparison with other studies conducted in Ontario, particularly in younger children. Various factors occurring during the study period may have influenced the results, including clinical testing of asymptomatic contacts, laboratory testing and methods and reporting practice, and a sensitive case definition. Further studies are needed to optimize methods for measuring VE to inform pertussis vaccine policy.     

Three-dimensional electromechanical mapping: imaging in the operating room of the future

BACKGROUND: Three-dimensional electromechanical mapping has previously been shown to be a clinically important tool for cardiac imaging and intervention. We hypothesized that this technology may be beneficial as an intraoperative modality for assessing cardiac hemodynamics and viability during cardiac surgery. We report here the use of this technology as an imaging modality for intraoperative cardiac surgery. METHODS: The tip of a locatable catheter connected to an endocardial mapping and navigating system is accurately localized while simultaneously recording local electrical and mechanical functions. Thus the three-dimensional geometry of the beating cardiac chamber is reconstructed in real time. The system was tested on 6 goats that underwent acute dynamic cardiomyoplasty and on 5 dogs that underwent left anterior descending (LAD) coronary artery ligation. RESULTS: The electromechanical mapping system provided an accurate three-dimensional reconstruction of the beating left ventricle during cardiomyoplasty. After the wrapping procedure, significant end-diastolic area reduction was noted in the base and mid parts of the heart (948 +/- 194 mm2 vs 1245 +/- 33 mm2, p = 0.021; and 779 +/- 200 mm2 vs 1011 +/- 80 mm2, p = 0.016). The area of the cross-section of the apex did not change during the operation. Acute infarcted tissue was characterized 3 days after LAD ligation by concomitant deterioration in both electrical and mechanical function. CONCLUSIONS: By providing both a clear view of the anatomical changes that occur during cardiac surgery, and an accurate assessment of tissue viability, electroanatomic mapping may serve as an important adjunct tool for imaging and analysis of the heart during cardiac surgery     

Evaluation of epicardial microwave ablation lesions: histology versus electrophysiology

Background

Pulmonary vein isolation is a hallmark in current surgical ablation for atrial fibrillation. However, validation of isolation remains cumbersome. We evaluated electrophysiologic and not histologic means to test isolation.

Methods

In 16 mongrel dogs, robot-assisted epicardial beating-heart microwave ablation (FLEX 10) was performed around the pulmonary veins. Electrophysiologic isolation was tested by pacing at 4 times threshold values inside and outside the pulmonary veins (exit and entrance block). The histology of lesions was studied for transmurality and continuity of the lesion lines. In 5 dogs, lesions were studied at various time intervals.

Results

Histologic evaluation of the lesions showed incomplete (48% ± 20%) circumferential myocardial damage in all dogs with acute lesions. Electrophysiologic evaluation showed completion of the box (entrance and exit block) in 8 dogs and in another 5 dogs after repeated ablation (p < 0.01 compared with histologic evaluation). Electrophysiologic evaluation of the dogs with chronic lesions showed completed lesions in 4 of 5 dogs directly after ablation. At follow-up (1 to 3 weeks), the isolations remained electrophysiologically complete. Histologic evaluation of the lesions 1 to 3 weeks after ablation showed complete (100%) circumferential lesions in all 4 dogs (p < 0.001 compared with the histology of dogs with acute lesions).

Conclusions

Directly after treatment, ablation lesions are best evaluated electrophysiologically, because complete (transmural and circumferential) lesions are not shown by histologic evaluation in the acute stage. After 1 to 3 weeks, the histology is in accordance with the electrophysiology. To obtain a complete isolation, online electrophysiologic evaluation during pulmonary vein microwave ablation is necessary to optimize the results.